2021 |
Elliott LK, Wall TF, 'Volatile release from maceral concentrates of pulverised coals used for pulverised coal injection at temperatures of 1550 °C and their relationship with density', Fuel, 297 (2021) [C1]
The impact of macerals and their pyrolysis behaviour on pulverized coal injection (PCI) combustion in blast furnaces is unclear. At present, a coal's combustibility is consid... [more]
The impact of macerals and their pyrolysis behaviour on pulverized coal injection (PCI) combustion in blast furnaces is unclear. At present, a coal's combustibility is considered to be related to its volatile content, as measured by the proximate analysis, alone, even though it is known that some coals¿ performances do not follow this trend Elliott et al. (2013). The impact of coal macerals, particularly vitrinite, on volatile release, was therefore assessed by pyrolysing maceral concentrates in a drop tube furnace with a preheated gas. Maceral concentrates produced from 5 coals with a range of rank were used. The density of the maceral concentrates was found to influence volatile release under elevated heating rates, at 1550 °C. The graphitic nature of the resulting char was also found to depend on the density of the maceral concentrate from which the char was produced.
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Nova |
2019 |
Xie W, Stanger R, Tran QA, Mahoney M, Lucas J, Yu J, Wall T, 'Impact of large sized inertinite particles on thermo-swelling and volatile release of coking coals', Fuel Processing Technology, 193 63-72 (2019) [C1]
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Nova |
2019 |
Zabihi O, Shafei S, Fakhrhoseini SM, Ahmadi M, Ajdari Nazarloo H, Stanger R, et al., 'Low-Cost Carbon Fibre Derived from Sustainable Coal Tar Pitch and Polyacrylonitrile: Fabrication and Characterisation.', Materials (Basel, Switzerland), 12 (2019) [C1]
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Nova |
2019 |
Lee S, Yu J, Mahoney M, Tremain P, Moghtaderi B, Tahmasebi A, et al., 'Study of chemical structure transition in the plastic layers sampled from a pilot-scale coke oven using a thermogravimetric analyzer coupled with Fourier transform infrared spectrometer', Fuel, 242 277-286 (2019) [C1]
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Nova |
2019 |
Tran QA, Stanger R, Xie W, Smith N, Lucas J, Wall T, 'An investigation of the molecular change in coal maceral concentrates prepared under dimensional heating condition', Fuel Processing Technology, 189 80-88 (2019) [C1]
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Nova |
2019 |
Lee S, Yu J, Mahoney M, Tahmasebi A, Stanger R, Wall T, Lucas J, 'In-situ study of plastic layers during coking of six Australian coking coals using a lab-scale coke oven', Fuel Processing Technology, 188 51-59 (2019) [C1]
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Nova |
2018 |
Liu D, Wall T, Stanger R, 'Experimental and modelling study on co-absorption of SO
This paper aims to set up the theoretical model for co-absorption of SO2 and CO2 into sodium based solutions. Instantaneous reaction for SO2 hydrolysis is assumed. For the hydroly... [more]
This paper aims to set up the theoretical model for co-absorption of SO2 and CO2 into sodium based solutions. Instantaneous reaction for SO2 hydrolysis is assumed. For the hydrolysis of CO2, there are two assumptions: finite kinetics and instantaneous reaction. Based on these two assumptions, the absorption rates of SO2 were separately calculated and compared with dynamic experiments in the well stirred reactor. The trend for the absorption rate of SO2 was well predicted by the instantaneous reaction for CO2. The relative error for the absolute rates of SO2 is high. The prediction based on the finite kinetics for CO2 hydrolysis at pH>3 agrees well with experiments. The influences of CO2 on the SO2 absorption rate is primarily through gas phase mass transfer coefficient and total sulphur concentration at the same pH. Depending on the existence of CO2 on SO2 absorption rate, five pH regimes for interaction were observed. At pH>11.42, the absorption rate of SO2/N2 is higher than that of SO2/CO2 due to the influence of gas phase mass transfer coefficient. At 7.8<pH<11.42, the absorption rate of SO2/N2 is similar with that of SO2/CO2 due to the counteraction of gas phase mass transfer coefficient and total sulphur in liquid. At 5.41<pH<7.8, the absorption rate of SO2/CO2 is higher due to the influence of total sulphur in liquid. At 2.8<pH<5.41, the absorption rate of SO2/CO2 is relative lower primarily due to the influence of gas phase mass transfer coefficient. At pH<2.8, the absorption rate of SO2/N2 is similar with that of SO2/CO2 due to liquid phase controlled region. Conversion of carbon and sulphur based ions at different pH and controlling regions for SO2 absorption rate were obtained. The work provides guidance for the design and operation of flue gas cooler for oxy-fuel combustion flue gas.
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2018 |
Liu D, Jin J, Gao M, Xiong Z, Stanger R, Wall T, 'Dataset for the estimation of costs for direct contact condenser', DATA IN BRIEF, 20 535-543 (2018)
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2018 |
Liu D, Jin J, Xiong Z, Stanger R, Wall T, 'Dynamic measurement of liquid-phase mass transfer coefficient and significance on the SO2 absorption rate', Asia-Pacific Journal of Chemical Engineering, 13 (2018) [C1]
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Nova |
2018 |
Xie W, Stanger R, Tran QA, Smith N, Wall T, Lucas J, 'Impact of Coal Pyrolysis Products as a Rheological Additive on Thermoplasticity of a Coking Coal', Energy and Fuels, 32 4382-4390 (2018) [C1]
Thermoplasticity is a determining factor for the development of the coke structure and coke strength. Mobile phase, whether vaporizable or not, may significantly affect thermoplas... [more]
Thermoplasticity is a determining factor for the development of the coke structure and coke strength. Mobile phase, whether vaporizable or not, may significantly affect thermoplasticity during coal coking. This work studies the effect of the mobile phase, including the volatile tar and extractable metaplast generated from one bituminous coking coal, on the thermo-swelling of the raw coal. The volatile tar was collected when the raw coal was heated from room temperature to 450 °C at a heating rate of 5 °C/min, while the metaplast was extracted from the heated char. Molecular properties of the tar and metaplast were characterized using a laser desorption/ionization-time of flight-mass spectrometry technique (LDI-TOF-MS). Thermo-swelling of the raw coal and its blends with the volatile tar and extractable metaplast was investigated using a computer-aided thermal analysis (CATA). The volatile (C and H) evolution rate of the heating coal samples was tracked using a dynamic elemental thermal analysis (DETA), and the weight loss rate was investigated using thermogravimetric analysis (TGA). It was found that the extracted metaplast has a higher molecular weight distribution than that of the volatile tar. The swelling and thermal changes of the heating coal increased with the addition of tar or metaplast. The weight loss rate prior to coal swelling increased with the additives, while the raw coal showed a higher volatile release after maximum swelling than the blends. The addition of metaplast into the raw coal led to greater swelling, increased exothermicity, and resulted in a higher thermal conductivity than the addition of volatile tar during the primary devolatilization, particularly when the additive was 20 wt % in the blend. Different influences of thermoplasticity of the blends indicated that the interactions between the additive and the coal are affected by the molecular weight distribution of the additive. These findings will aid in the selection of the additive for improving thermoplasticity of low-caking coals to benefit coke production.
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Nova |
2018 |
Tran QA, Stanger R, Xie W, Smith N, Lucas J, Wall T, 'Thermoplastic development of coking and non-coking maceral concentrates and molecular weight distribution of their pyrolysis products', Journal of Analytical and Applied Pyrolysis, 129 72-85 (2018) [C1]
A suit of nitrogen-dried maceral concentrates derived from a coking coal and a non-coking coal was investigated to reveal the impact of varying coal main organic constituent, the ... [more]
A suit of nitrogen-dried maceral concentrates derived from a coking coal and a non-coking coal was investigated to reveal the impact of varying coal main organic constituent, the vitrinite, on their thermoplasticity and pyrolysis products. The thermoplastic development of maceral concentrates during pyrolysis was evaluated via their thermo-swelling and dynamic volatile release. These measurements were then linked to molecular weight distributions of vaporised tars and tetrahydrofuran (THF) extracts obtained from heat-treated samples. Regardless of the vitrinite content, only coking macerals agglomerated during pyrolysis while non-coking macerals retained their powdered structure. This result indicated that although concentrating the vitrinite could alter the extent of coal thermoplasticity, such process could not grant or remove thermoplasticity from a maceral concentrate. This was reflected in the similar molecular weight distribution of solvent extracts produced between the parent coals and their concentrates. In specific, coking concentrates generated extractable materials with a relatively more complex structure, consisting of a bimodal molecular weight distribution with 12¿14 Da repeating structures at <600 Da and 24 Da reoccurring units between 600 and ~1500 Da. Solvent extracts isolated from non-coking concentrates, on the other hand, possessed a unimodal molecular weight distribution with only 12¿14 Da repeating structures extending to ~800 Da. The absence of high-range molecular weight materials (the 24 Da repeating units) in non-coking coal and its concentrates was speculated to play a vital role to their inability to exhibit thermoplastic behaviour during pyrolysis.
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Nova |
2018 |
Stanger R, Tran QA, Browne M, Lucas J, Naebe M, Height M, Wall T, 'Evaluating the Thermal Extrusion Behavior of a Coking Coal for Direct Carbon Fiber Production', Energy and Fuels, 32 4528-4537 (2018) [C1]
This study outlines a novel thermal extrusion system and methodologies for evaluating the potential to manufacture carbon fiber directly from thermoplastic coals. It is envisioned... [more]
This study outlines a novel thermal extrusion system and methodologies for evaluating the potential to manufacture carbon fiber directly from thermoplastic coals. It is envisioned that the intermediate product will be further refined by spinning down to commercial fiber sizes and thermal annealing. Commercial melt spinning is used for manufacturing carbon fibers from pitch-based feed materials, and a similar approach for plasticized coal is likely to be a lower risk option. However, the critical aspect of using coal for this purpose is its behavior inside a higher pressure extrusion unit and the need to characterize its rheology. This work has evaluated the thermoplastic development needed for extrusion of a single coking coal in terms of the heating rate and residence time and characterized the extruded fiber product. It was observed that the coal underwent a preliminary softening phase prior to extruding at significant speed. This phase appeared necessary to develop the critical viscosity for extrusion and was affected by the heating rate. The size of the orifice that the coal was extruded through also impacted the point of extrusion, with the smaller 0.5 mm hole requiring lower viscosity to be developed to flow at steady state. Other operating modes were developed to examine the thermoplastic properties of the coal over an extended residence time, and it was found that the coal could be maintained up to 60 min at selected temperatures. The product fiber was larger than the commercial size, appearing slightly larger than the orifice size. Internal porosity and surface roughness were observed as coal-based fiber qualities in need of controlling, along with the mineral content and size.
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Nova |
2018 |
Liu D, Jin J, Gao M, Xiong Z, Stanger R, Wall T, 'A comparative study on the design of direct contact condenser for air and oxy-fuel combustion flue gas based on Callide Oxy-fuel Project', International Journal of Greenhouse Gas Control, 75 74-84 (2018) [C1]
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Nova |
2017 |
Stanger R, Tran QA, Smith N, Kennedy E, Stockenhuber M, Lucas J, Wall T, 'Separation and analysis of high range extractable molecules formed during coal pyrolysis using coupled thin layer chromatography-imaging mass spectrometry (TLC-LDI-IMS)', FUEL, 196 269-279 (2017) [C1]
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Nova |
2016 |
Stanger R, Tran QA, Xie W, Smith N, Lucas J, Yu J, et al., 'The use of LDI-TOF imaging mass spectroscopy to study heated coal with a temperature gradient incorporating the plastic layer and semi-coke', Fuel, 165 33-40 (2016) [C1]
This work has used high range imaging mass spectrometry to study a coal sample that has undergone heating with a temperature gradient. A custom made hotplate was heated to 1000°C ... [more]
This work has used high range imaging mass spectrometry to study a coal sample that has undergone heating with a temperature gradient. A custom made hotplate was heated to 1000°C and the coal was allowed to heat naturally through conduction to produce a large thermal gradient typical of conditions in a coke oven. The sample was quenched, sectioned and analysed using laser desorption time of flight imaging mass spectrometry (LDI-TOF-IMS) to study the molecular changes that occur within the plastic layer and in the semi-coke. The raw coal was observed to have a molecular weight range between 500 and 20,000 Da with a peak occurring at 2000 Da. The plastic layer was observed to have a prevalence for increasing 500-1000 Da structures though this formed part of the larger molecular weight range. Resolidification of the plastic layer coincided with a rise in 4000 Da structures. The semi-coke spectrum had a series of repeating peaks separated by 24 Da extending from 1000 Da to 3000 Da. This was considered evidence of broad molecular ordering. A second phenomenon was observed in the semi-coke associated with low range molecular weights (50-300 Da). This appeared as high intensity signals in a molecular range typically considered as ion fragments (being too low in size to remain in the high vacuum environment). It was speculated that these low range structures may be associated with the coking of volatile tars exiting the hot-side of the plastic layer through high temperature semi-coke. Overall, this preliminary work provides a novel methodology to study the heating impacts during coking on a molecular level.
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Nova |
2016 |
Gupta AK, Levendis YA, Wall T, 'Special Issue: Selected Papers From the 40th International Technical Conference on Clean Coal and Fuel Systems', JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME, 138 (2016)
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2016 |
Quang AT, Stanger R, Xie W, Smith N, Lucas J, Wall T, 'Impacts of Mild Pyrolysis and Solvent Extraction on Coking Coal Thermoplasticity', ENERGY & FUELS, 30 9293-9302 (2016) [C1]
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Nova |
2016 |
Gupta AK, Levendis YA, Wall T, 'Special issue of JERT form Clearwater Confernece', Journal of Energy Resources Technology, Transactions of the ASME, 138 (2016)
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2016 |
Yang N, Yu JL, Dou JX, Tahmasebi A, Song H, Moghtaderi B, et al., 'The effects of oxygen and metal oxide catalysts on the reduction reaction of NO with lignite char during combustion flue gas cleaning', Fuel Processing Technology, 152 102-107 (2016) [C1]
The development of lignite-char-supported metal oxide catalyst for reduction of nitric oxide (NO) is investigated in this paper. The characteristics of NO reduction by copper and ... [more]
The development of lignite-char-supported metal oxide catalyst for reduction of nitric oxide (NO) is investigated in this paper. The characteristics of NO reduction by copper and iron oxide catalysts supported on activated lignite chars (ALC) was studied using a fixed-bed reactor at 300 °C. The results showed that the impregnation of Cu on ALC resulted in higher catalytic reactivity during NO reduction compared with that of Fe. Chemisorption of O2 and NO on Cu/ALC catalyst was found to play an important role in denitrification. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses showed that chemically adsorbed oxygen facilitates the formation of C(O) complex and oxidation of Cu0 to Cu+ for Cu/ALC catalyst. The C(O) intermediates and C*production formed due to the fact that C/O2 reaction promoted the reduction of NO. It is suggested that the catalytic reaction of NO in this case comprised of C/O2 reaction, C(O)/NO reaction and formation of N2 and CO2. Cu seemed to have significantly promoted the C(O) formation and CO oxidation compared with Fe. The catalytic reactivity of Cu species for C(O) formation and CO oxidation followed the order of Cu0 > Cu+ > Cu2 +. Fe3O4 was believed to be the active phase in Fe catalyst. The oxygen and char-supported metal catalysts significantly promoted C/NO reaction, and therefore may lead to a lower operation temperature of NOx removal.
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Nova |
2016 |
Stanger R, Quang AT, Attalla T, Smith N, Lucas J, Wall T, 'The pyrolysis behaviour of solvent extracted metaplast material from heated coal using LDI-TOF mass spectroscopy measurements', JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS, 120 258-268 (2016) [C1]
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Nova |
2016 |
Tran QA, Stanger R, Xie W, Lucas J, Yu J, Stockenhuber M, et al., 'Maceral separation from coal by the Reflux Classifier', FUEL PROCESSING TECHNOLOGY, 143 43-50 (2016) [C1]
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Nova |
2016 |
Stanger R, Belo L, Ting T, Spero C, Wall T, 'Mercury and SO3 measurements on the fabric filter at the Callide Oxy-fuel Project during air and oxy-fuel firing transitions', INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, 47 221-232 (2016) [C1]
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Nova |
2016 |
Liu D, Wall T, Stanger R, 'CO2 quality control in Oxy-fuel technology for CCS: SO2 removal by the caustic scrubber in Callide Oxy-fuel Project', INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, 51 207-217 (2016) [C1]
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Nova |
2016 |
Liu D, Xiong Z, Jin J, Wall T, Stanger R, 'Conceptual design of a packed bed for the removal of SO2 in Oxy-fuel combustion prior to compression', INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, 53 65-78 (2016) [C1]
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Nova |
2016 |
Xie W, Wall T, Lucas J, Mahoney M, Stanger R, 'Thermo-swelling Behavior of Australian Coking Coals from Different Basins: Relating to Rank and Maceral Compositions', ENERGY & FUELS, 30 10126-10135 (2016) [C1]
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Nova |
2016 |
Xie W, Wall T, Lucas J, Mahoney M, Stanger R, 'Chemical Changes of Australian Coking Coals from Different Basins with Various Ranks and Maceral Compositions: Linking to Both Physical and Thermal Changes', ENERGY & FUELS, 30 10136-10147 (2016) [C1]
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Nova |
2016 |
Tran QA, Stanger R, Xie W, Smith N, Lucas J, Wall T, 'Linking Thermoplastic Development and Swelling with Molecular Weight Changes of a Coking Coal and Its Pyrolysis Products', Energy and Fuels, 30 3906-3916 (2016) [C1]
The thermoplastic development of an Australian coking coal was investigated by linking thermal swelling with changes in molecular weight of its pyrolysis products. Coal thermal sw... [more]
The thermoplastic development of an Australian coking coal was investigated by linking thermal swelling with changes in molecular weight of its pyrolysis products. Coal thermal swelling was investigated together with volatiles evolution and characterization of generated volatiles (including volatile tar and light gases). The molecular weight distributions of coal and its solvent extracts were measured by using laser desorption/ionization time of flight mass spectroscopy (LDI-TOF-MS). Solvent extraction (by acetone and tetrahydrofuran (THF)) was initially used on the raw coal to aid interpretation of thermoswelling by volumetric expansion measurements. The removal of ~2% solvent-soluble matter from the raw coal (the mobile phase) reduced its swelling extent during heating by up to 22% (from 86% down to 68% and 64% for acetone- and THF-residues, respectively). Volatile release after solvent treatment remained unaffected. This suggested that the majority of the coals swelling behavior could be attributed to the formation of heat-generated liquid matter (the Metaplast) during pyrolysis. Broad molecular weight changes were found in the solvent extractable component (metaplastic material extracted by acetone and THF) of the semicoke. Prior to softening (350 °C), the extractable components were composed of molecules mainly <500 Da. The upper limit in molecular weight distribution of solvent extracts increased significantly to 1800 Da at the onset of swelling (400-450 °C) and decreased back to ~500 Da at the end of swelling (500 °C). The spectra showed that the volatile tar and acetone extract (the light solvent extract) consisted of similar repeating structures separated 12-14 Da apart. As the treatment temperature increased, the molecular weight distribution of volatile tar increased in molecular mass, approaching that of the acetone extract distribution (~600 Da). The THF extract molecular weight distribution was a mixture of 12-14 and 24 Da repeating units which only became apparent at molecular weight above 600 Da. The LDI-TOF-MS analysis of the solid coal showed that it contained a distribution of molecular structures centered at 2000 Da and spanning between 500 and 7000 Da. This raw coal spectrum also contained multiple repeating mass lines every 24 Da apart. Overall, these results suggested that the coal consisted of complicated structures which subsequently degraded into smaller fragments capable of forming a complex intermediate liquid phase and a distribution of lighter volatile tar species.
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Nova |
2016 |
Belo LP, Elliott LK, Stanger RJ, Wall TF, 'Impacts of Sulfur Oxides on Mercury Speciation and Capture by Fly Ash during Oxy-fuel Pulverized Coal Combustion', Energy and Fuels, 30 8658-8664 (2016) [C1]
Coal-fired utility boilers are the single largest anthropogenic source of mercury emissions. Mercury is a naturally occurring trace element in coal and, when combusted, may exist ... [more]
Coal-fired utility boilers are the single largest anthropogenic source of mercury emissions. Mercury is a naturally occurring trace element in coal and, when combusted, may exist in three different forms: Hg0, Hg2+, or Hg particulate. During oxy-fuel combustion, impurity concentrations, such as SOx, NOx, and Hg, can be up to 4 times higher than concentrations in air combustion. An increased mercury concentration is of concern because mercury is known to attack aluminum heat exchangers required in the compression of CO2. As a result of the elevated concentrations during oxy-fuel conditions, interactions of Hg and SOx were investigated in this study to verify if there is any competition between SOx and Hg. The effect of Hg, SOx, H2O, and temperature on the native capture of Hg by fly ash was assessed using a quartz flow reactor packed with fly ash to simulate a bag filter. Doubling Hg in the system from 5 to 10 µg/Nm3 doubled the amount of Hg captured in the fly ash from 1.6 to 2.8% and increased the amount of Hg unaccounted from 5.8 to 18.1%. Increased SO2 decreased the proportion of Hg0 in the flue gas. The temperature in the bag filter was found to have a large impact on the mercury capture by fly ash. As the temperature was increased from 90 to 200 °C, Hg0 in the flue gas was found to increase from 77.9 to 98.3%, indicating better capture of Hg at lower temperatures.
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Nova |
2015 |
Xie W, Stanger R, Lucas J, Mahoney M, Elliott L, Yu J, Wall T, 'Thermo-swelling Properties of Particle Size Cuts of Coal Maceral Concentrates', Energy & Fuels, 29 4893-4901 (2015) [C1]
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Nova |
2015 |
Liu D, Wall T, Stanger R, 'CO2 quality control through scrubbing in oxy-fuel combustion: Rate limitation due to S(IV) oxidation in sodium solutions in scrubbers and prior to waste disposal', INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, 39 148-157 (2015) [C1]
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Nova |
2015 |
Liu D, Wall T, Stanger R, Luo C, 'CO
Oxy-fuel combustion is a promising CCS technology which is being demonstrated prior to commercialization. While the flue gas in oxy-fuel combustion is concentrated in CO2, it cont... [more]
Oxy-fuel combustion is a promising CCS technology which is being demonstrated prior to commercialization. While the flue gas in oxy-fuel combustion is concentrated in CO2, it contains impurities such as SO2. The elimination of SO2 can provide a clean CO2 stream ready for storage. SO2 is commonly washed by sodium based spray towers with high efficiency but CO2 impacts are significant. A theoretical model was developed based on the two-film mass transfer model, and considering both the SO2 and CO2 reactions with sodium solutions. This model was firstly used to simulate the dynamic experimental results reported in our previous paper to confirm its applicability. With this model, simulations then were carried out on the absorption rate of SO2 into droplets with three droplet sizes: 100µm, 500µm and 1000µm, one sodium concentration of 0.08M (back calculated from liquid analysis), a range of pH from 4 to 12.5 and a range of SO2 concentrations from 19ppm to 1500ppm.Simulations focus on the impacts of droplet position, gas phase CO2 and droplet size on the absorption rate of SO2. These impacts are closely related with pH values. Taking a typical pH of 7 for example, the absorption rates of SO2 for droplets close to nozzles which move relative to the gas are significantly higher than these below nozzles which are at the terminal velocities, and the differences between two positions are larger for higher concentrations of SO2 with the concentrations range from 200ppm to 1500ppm. CO2 has a negative impact on the absorption rate of SO2 through reducing the gas phase mass transfer coefficient of SO2 in the gas phase controlled region and also through generating more acidic conditions at the liquid phase interface. Reducing the droplet size from 500µm to 100µm has a more significant improvement on the absorption rate of SO2 than from 1000µm to 500µm. Result: have implications in the controlling region and the operational liquid pH region. The controlling region is related to the droplet position. The droplets close to nozzles are located in the mixed controlled region or the gas film controlled region; and the droplets below nozzles can be located in three regions depending on the concentration of SO2 and pH. A lower concentration of SO2 and a higher pH are favourable for the absorption rates of SO2 to be located in the gas phase controlled region.The operational pH of the exit liquid may be established based on two criteria: a reasonable absorption rate of SO2 and a sodium reagent loss as NaHCO3. The optimal operational region is then in the region 2 where the absorption rate of SO2 is still high and reagent use is minimized. The region 2 can be further divided into four sub regions. In the region 2-1 and the region 2-2, the absorption rate is moderate, but there is too much Na+ wasted for CO2 capture. In the region 2-3, there is a moderate amount of Na+ wasted for CO2 capture. In the region 2-4, Na+ wasted for CO2 capture is minimized, but the effective ratio of Na+ is still not the maximum.The necessary operational pH region graph can be used to guide the operation of a spray tower.
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Nova |
2015 |
Stanger R, Ting T, Belo L, Spero C, Wall T, 'Field measurements of NO x and mercury from oxy-fuel compression condensates at the Callide Oxyfuel Project', International Journal of Greenhouse Gas Control, 42 485-493 (2015) [C1]
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Nova |
2015 |
Xie W, Stanger R, Wall TF, Lucas JA, Mahoney MR, 'Associations of physical, chemical with thermal changes during coking as coal heats - Experiments on coal maceral concentrates', Fuel, 147 1-8 (2015) [C1]
Dynamic measurements of physical, chemical and thermal changes in the transformation of coal maceral concentrates were made during heating at a rate of 10°C/min to 1000°C. The end... [more]
Dynamic measurements of physical, chemical and thermal changes in the transformation of coal maceral concentrates were made during heating at a rate of 10°C/min to 1000°C. The endothermic and exothermic processes were identified by measurements of apparent specific heat while the fluidity was indicated by the estimated thermal conductivity. Measurements of swelling and bed permeability were made, with continuous quantitative elemental analysis of gases and tars as they evolved. Data for two coal concentrates of high and moderate vitrinite indicate that the same reactions and events are occurring for the two samples, but to a greater extent for the high vitrinite sample. The research has noted the significance of evolved tars in the early events, being the lowest temperature event identified, with rapid tar evolution prior to the onset of swelling associated with permeability change. Further tar release and gas evolution is associated with a rapid swelling event, this event being substantially greater for the high vitrinite sample. The data has also quantified contraction at higher temperatures following swelling which is associated with the release of hydrogen containing gases. Evolved tars from the high vitrinite sample showed elevated H/C ratio indicating that vitrinite tars appear to be more aliphatic than those evolved from inertinite. A comparison of measured swelling with estimated volumetric flow rate of the volatiles has indicated that thermo-expansion of coal utilised up to 21% of the volatiles to drive bubble growth. This utilisation rate varied significantly across the plastic temperature range.
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Nova |
2015 |
Dou J, Yu J, Tahmasebi A, Yin F, Gupta S, Li X, et al., 'Ultrasonic-assisted preparation of highly reactive Fe-Zn sorbents supported on activated-char for desulfurization of COG', Fuel Processing Technology, 135 187-194 (2015) [C1]
The desulfurization properties of Fe-Zn sorbent prepared by impregnating Fe and Zn into lignite char via ultrasonic-assisted impregnation (UAI) were investigated in comparison wit... [more]
The desulfurization properties of Fe-Zn sorbent prepared by impregnating Fe and Zn into lignite char via ultrasonic-assisted impregnation (UAI) were investigated in comparison with the mechanical stirring (MS) method. The sulfidation experiments were carried out using a fixed-bed quartz reactor under ambient pressure. The amounts of metals loaded into char were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). The crystalline phases and chemical structure of sorbents before and after sulfidation were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. The morphology of sorbents was analyzed by using scanning electron microscope (SEM) with an energy dispersive X-ray (EDX) auxiliary. The experimental results showed that metal oxides as the active components were evenly dispersed on char as nanoparticles. The impregnation of active components was significantly improved by the ultrasonic-assisted impregnation method. When sorbents were prepared by ultrasonic-assisted impregnation, the metal oxide particles became smaller and more evenly dispersed on the char matrix which resulted in higher desulfurization efficiency and sulfur uptake capacity of the sorbents. The BET results showed that the physical properties of sorbents (surface area and pore volume) significantly improved when prepared by UAI method compared to MS method. The sulfidation temperature had a significant effect on desulfurization performance of char supported sorbents. The Fe:Zn molar ratio of 2:1, and impregnation time of 9 h were suggested as the optimal preparation conditions during ultrasonic-assisted impregnation.
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Nova |
2015 |
Stanger R, Borrowdale J, Smith N, Xei W, Tran QA, Lucas J, Wall T, 'Changes in Solvent-Extracted Matter for Heated Coal during Metaplast Formation Using High-Range Mass Spectrometry', Energy and Fuels, 29 7101-7113 (2015) [C1]
A fundamental study was undertaken to characterize the changes in solvent-extracted matter formed during the thermoplastic phase of coking. Coal samples were heated to fixed tempe... [more]
A fundamental study was undertaken to characterize the changes in solvent-extracted matter formed during the thermoplastic phase of coking. Coal samples were heated to fixed temperatures within the pyrolytic plastic range of 400-500 °C, and the volatile material was extracted in a two-stage extraction with acetone (light extract) and then tetrahydrofuran (THF heavy extract). The extracted material was analyzed using laser desorption ionization (time-of flight) mass spectrometry (LDI-TOF-MS). The LDI-TOF-MS results showed that three extracted fractions could be broadly classified here as overlapping molecular weight ranges as volatile tars (200-450 Da), light acetone-soluble extract (250-500 Da), and heavy THF-soluble extract (300-1200 Da). A further class of compounds was identified from THF extraction of the raw coal in the range of 600-2500 Da that required higher laser powers to ionize and was not observed in the thermally generated samples. Negligible changes were observed in the composition of the acetone-soluble extracts with temperature, while the THF-soluble extract showed smaller proportions of larger molecules with higher treatment temperatures. It was observed that each molecular weight spectrum showed repeating structural units forming peaks every 12-14 Da (homologous series), with distributions of species around each peak. The volatile tar and acetone-soluble material shared common repeating structures also evident in the raw coal extract. This suggested that the material in this fraction was thermally stable over the analyzed temperature range. The repeating features of the THF-soluble extract species appeared to be structurally different. Overall, this work has indicated that development of extractable matter expected to be associated with fluidity during coking and subsequent resolidification relies on <1000 Da compounds. The results showed that >600 Da compounds are thermally sensitive. Compounds with molecular weights of <450 Da may be removed during coking, possibly as a vapor, resulting in a reduction in fluidity. There has been speculation that the thermally stable (acetone-soluble) material identified in both raw coal extract and those from thermally treated samples may be capable of undergoing a phase change to initiate plastic deformation.
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Nova |
2015 |
Stanger R, Wall T, Spörl R, Paneru M, Grathwohl S, Weidmann M, et al., 'Oxyfuel combustion for CO2 capture in power plants', International Journal of Greenhouse Gas Control, 40 55-125 (2015) [C1]
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Nova |
2015 |
Stanger R, Ting T, Spero C, Wall T, 'Oxyfuel derived CO2 compression experiments with NOx, SOx and mercury removal-Experiments involving compression of slip-streams from the Callide Oxyfuel Project (COP)', International Journal of Greenhouse Gas Control, 41 50-59 (2015) [C1]
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Nova |
2015 |
Liu D, Wall T, Stanger R, 'CO
Oxy-fuel combustion is a promising CCS technology which is being demonstrated prior to commercialisation. While the flue gas in oxy-fuel combustion is concentrated in CO2, it cont... [more]
Oxy-fuel combustion is a promising CCS technology which is being demonstrated prior to commercialisation. While the flue gas in oxy-fuel combustion is concentrated in CO2, it contains impurities such as SO2. The elimination of SO2 can provide a clean CO2 stream ready for storage. This paper is to understand the absorption of SO2 in scrubbing relevant to those used in oxy-fuel technology.Steady state experiments were conducted in a continuous well stirred reactor to understand the absorption rate of SO2/CO2 into a total concentration of 0.28M of mixtures of NaHSO3 and NaHCO3 simulating liquids formed by scrubbers using NaOH as the reagent at solution pH values from 4 to 7 with the exiting gas concentrations of SO2 from 19ppm to 1500ppm and a constant CO2 concentration of 70%. Online measurement included gas phase SO2 and liquid pH, and offline measurement included CO2 (aq), HCO3-, S (IV), SO32- and S (VI) after each experiment. Three aspects investigated were the impacts of pH on the solution chemistry, the significance of solution pH and the concentration of gas phase SO2 on the absorption rate of SO2.The total sulphur concentration in liquid was found to be related to the effectiveness of Na+. The effective ratio of Na+ can be defined as the total sulphur to Na+ ratio and this effectiveness ratio of Na+ is pH dependent. At pH<5, Na+ is 99% effective. It reduces dramatically from 99% at a pH 5 to less than 15% at pH above 7. With regard to carbon based species also absorbed, super saturation of CO2 (aq) was observed at pH>5.5. The concentration of HCO3- increases dramatically above pH 6 and below this pH, the concentration of HCO3- is negligible.The absorption rate of SO2 was found to increase with pH with some increase with the concentration of SO2. The operational pH window for scrubbing may be defined by an upper limit pH where the absorption rate of SO2 starts to decreases from the maximum absorption rate of SO2 and the lower limit pH where the absorption rate of SO2 reduces to half of the maximum absorption rate of SO2. Both the upper limit and the lower limit decrease initially and stay stable with the concentration of SO2. This decrease is caused by the reversible reaction of the hydrolysis of SO2 and confirmed by equilibrium experiments of SO2 and sodium solutions. Operation within region 2 (pH 5-6) is recommended, depending on the scrubber design. The operation exit pH of the produced liquid can be varied within the region.The absorption rates of SO2 obtained in the steady state experiments were predicted by a model based on the instantaneous reaction assumption. This model generally overestimates the absorption rates of SO2 at pH values below 6 indicating a kinetic limitation of SO2 and water reaction at low pH values. The analysis on the controlling regions indicates that the gas side mass transfer resistance decreases with the concentration of SO2. Liquid side resistance becomes more important at a lower pH and a higher concentration of SO2.
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Nova |
2014 |
Stanger R, Xie W, Wall T, Lucas J, Mahoney M, 'Dynamic measurement of coal thermal properties and elemental composition of volatile matter during coal pyrolysis', Journal of Materials Research and Technology, 3 2-8 (2014)
A new technique that allows dynamic measurement of thermal properties, expansion and the elemental chemistry of the volatile matter being evolved as coal is pyrolysed is described... [more]
A new technique that allows dynamic measurement of thermal properties, expansion and the elemental chemistry of the volatile matter being evolved as coal is pyrolysed is described. The thermal and other properties are measured dynamically as a function of temperature of the coal without the need for equilibration at temperature. In particular, the technique allows for continuous elemental characterisation of tars as they are evolved during pyrolysis and afterwards as a function of boiling point. The technique is demonstrated by measuring the properties of maceral concentrates from a coal. The variation in heats of reaction, thermal conductivity and expansion as a function of maceral composition is described. Combined with the elemental analysis, the results aid in the interpretation of the chemical processes contributing to the physical and thermal behaviour of the coal during pyrolysis. Potential applications in cokemaking studies are discussed. © 2013 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda. All rights reserved.
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2014 |
Spörl R, Walker J, Belo L, Shah K, Stanger R, Maier J, et al., 'SO
The sulfur oxide (SOx) concentrations during oxy-fuel combustion are generally higher compared to conventional air firing. The higher SO x concentrations, particularly sulfur trio... [more]
The sulfur oxide (SOx) concentrations during oxy-fuel combustion are generally higher compared to conventional air firing. The higher SO x concentrations, particularly sulfur trioxide (SO3) in combination with high concentration of water in the recycled flue gas, increase the sulfuric acid dew point temperature in oxy-fuel fired systems, thereby increasing allowable flue gas temperatures and reducing the thermal efficiency of a power plant. This paper presents results of experiments carried out at a 20 kW once-through combustion rig of the Institute of Combustion and Power Plant Technology (IFK) of the University of Stuttgart simulating different extents of oxy-fuel recycle gas cleaning by impurities injection to the oxidant gas of a once-through combustion reactor. Three Australian coals that have previously been tested under air and oxy-fuel conditions at the Aioi furnace of IHI in Japan were used in the experiments. The SOx emissions were measured, conversion ratios of sulfur dioxide (SO2) to SO3 were calculated, and results were compared with existing literature, finding good agreement. The experiments with different extents of recycle gas cleaning and therefore different SO2 levels in the system, revealed differences in the SO3 generation behavior: A coal-specific trend of increasing conversion ratios of SO2 to SO3 with increased flue gas SO2 levels was observed that could be related to the ash composition of the three different coals. The capture of SOx in a baghouse filter was also evaluated. Acid dew point temperatures (ADPs) for the flue gas were calculated for the various firing conditions. Acid dew point (ADP) temperatures increased by up to 50°C when changing from air to oxy-firing with recycling of H2O and SO2. Considerable differences in the ADPs were found for different extents of oxy-fuel recycle gas treatment and were evaluated in respect to power plant efficiency implications. © 2014 American Chemical Society.
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Nova |
2014 |
Tahmasebi A, Yu J, Su H, Han Y, Lucas J, Zheng H, Wall T, 'A differential scanning calorimetric (DSC) study on the characteristics and behavior of water in low-rank coals', Fuel, 135 243-252 (2014) [C1]
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Nova |
2014 |
Shah K, Atkin R, Stanger R, Wall T, Moghtaderi B, 'Interactions between vitrinite and inertinite-rich coals and the ionic liquid - [bmim][Cl]', Fuel, 119 214-218 (2014) [C1]
The interactions between vitrinite and inertinite-rich coals and the ionic liquid butylimidazolium chloride ([bmim][Cl]) heated to 100 C have been characterised. Differences in th... [more]
The interactions between vitrinite and inertinite-rich coals and the ionic liquid butylimidazolium chloride ([bmim][Cl]) heated to 100 C have been characterised. Differences in the interactions of coal macerals and ionic liquids have been identified. [bmim][Cl] is able to dissolve 22 wt% of a high-vitrinite coal fraction compared to 14 wt% of a high-inertinite coal fraction. The vitrinite-rich coal fraction tends to swell to a greater extent compared to the inertinite-rich coal fraction, which was fractured and fragmented rather than swelled. © 2013 Published by Elsevier Ltd. All rights reserved.
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Nova |
2014 |
Spoerl R, Belo L, Shah K, Stanger R, Giniyatullin R, Maier J, et al., 'Mercury Emissions and Removal by Ash in Coal-Fired Oxy-fuel Combustion', ENERGY & FUELS, 28 123-135 (2014) [C1]
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Nova |
2014 |
Song H, Shah K, Doroodchi E, Wall T, Moghtaderi B, 'Analysis on Chemical Reaction Kinetics of CuO/SiO2 Oxygen Carriers for Chemical Looping Air Separation', ENERGY & FUELS, 28 173-182 (2014) [C1]
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Nova |
2014 |
Wang N, Yu J, Tahmasebi A, Han Y, Lucas J, Wall T, Jiang Y, 'Experimental Study on Microwave Pyrolysis of an Indonesian Low-Rank Coal', ENERGY & FUELS, 28 254-263 (2014) [C1]
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Nova |
2014 |
Meng F, Yu J, Tahmasebi A, Han Y, Zhao H, Lucas J, Wall T, 'Characteristics of Chars from Low-Temperature Pyrolysis of Lignite', ENERGY & FUELS, 28 275-284 (2014) [C1]
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Nova |
2014 |
Li H, Elliott L, Rogers H, Wall T, 'Comparative Study on the Combustion Performance of Coals on a Pilot-Scale Test Rig Simulating Blast Furnace Pulverized Coal Injection and a Lab-Scale Drop-Tube Furnace', ENERGY & FUELS, 28 363-368 (2014) [C1]
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Nova |
2014 |
Meng F, Tahmasebi A, Yu J, Zhao H, Han Y, Lucas J, Wall T, 'Low-Temperature Oxidation Characteristics of Lignite Chars from Low-Temperature Pyrolysis', Energy & Fuels, 28 5612-5622 (2014) [C1]
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Nova |
2014 |
Song H, Shah K, Doroodchi E, Wall T, Moghtaderi B, 'Reactivity of Al
The chemical looping air separation (CLAS) is a novel method for producing high-purity oxygen, which can be effectively integrated to oxy-fuel power plants. CuO/Cu2O, Mn2O3/Mn3O 4... [more]
The chemical looping air separation (CLAS) is a novel method for producing high-purity oxygen, which can be effectively integrated to oxy-fuel power plants. CuO/Cu2O, Mn2O3/Mn3O 4, and Co3O4/CoO have been found to be the most thermodynamically suitable oxidation pairs for the CLAS process. In the current study, the reactivity and stability of these metal oxides were analyzed further. A total of six different oxygen carrier samples were prepared by the dry impregnation method on SiO2 and Al2O3 supports. Their redox behavior has been investigated in a thermogravimetric analyzer (TGA) at four different temperatures, i.e., 800, 850, 900, and 950 C, where the temperature-programmed oxygen release and oxidation were applied for 5 continuous cycles using nitrogen and air, respectively. The results indicate that, although relatively all oxygen carriers exhibited good reactivity, CuO/Cu2O with SiO2 and Co3O4/CoO with Al2O3 were found to be most stable. Furthermore, oxygen transport capacity (OTC) (%) and rate of oxygen transport (ROT) (% min-1) were calculated. It was found that Cu oxide with SiO 2 has the highest OTC of 4.77% as well as the highest ROT of 5.1 and 10.9% min-1 for oxygen release and oxidation, respectively, at 950 C. The CuO/SiO2 oxygen carrier also exhibited better stability for the 41 continuous cycle test, with only 10.3% loss in OTC compared to 22.3% for Co3O4/Al2O3. The grain size growth was found to be the key cause in the loss of OTC. The oxygen concentration in the outlet stream for the CuO/SiO2 oxygen carrier was measured in packed-bed experiments at different temperatures. It was observed that the oxygen concentration at the outlet of the reactor was consistent with the equilibrium values at studied temperatures. © 2014 American Chemical Society.
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Nova |
2014 |
Belo LP, Spörl R, Shah KV, Elliott LK, Stanger RJ, Maier J, Wall TF, 'Sulfur capture by fly ash in air and oxy-fuel pulverized fuel combustion', Energy and Fuels, 28 5472-5479 (2014) [C1]
Ash produced during oxy-fuel combustion is expected to differ from ash produced during air combustion because of the higher CO2 and SO 2 atmospheres in which it is generated. For ... [more]
Ash produced during oxy-fuel combustion is expected to differ from ash produced during air combustion because of the higher CO2 and SO 2 atmospheres in which it is generated. For a quantitative understanding of the sulfation behavior of fly ash in oxy-fuel combustion, fly ash from three commercial Australian sub-bituminous coals was tested and decomposed under an inert atmosphere. Thermal evolved gas analysis was completed for ash produced in both air and oxy-fuel environments. Pure salts were also tested under the same conditions to allow for identification of the species in the ash that capture sulfur, along with thermodynamic modeling using FactSage 6.3. Sulfur evolved during the decomposition of air and oxy-fuel fly ash was compared to the total sulfur in the ash to close the sulfur balance. Both total sulfur captured by the ash and sulfur evolved during decomposition were higher for oxy-fuel fly ash than their air counterparts. Correlations of capture with ash chemistry are presented. © 2014 American Chemical Society.
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Nova |
2014 |
Yu J, Jiang Y, Tahmasebi A, Han Y, Li X, Lucas J, Wall T, 'Coal Oxidation under Mild Conditions: Current Status and Applications', Chemical Engineering & Technology, 37 1635-1644 (2014) [C1]
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Nova |
2014 |
Belo LP, Elliott LK, Stanger RJ, Spörl R, Shah KV, Maier J, Wall TF, 'High-temperature conversion of SO
The reaction of SO2 with fly ash in the presence of O2 and H2O involves a series of reactions that lead to the formation of SO3 and eventually H2SO4. Homogeneous experiments were ... [more]
The reaction of SO2 with fly ash in the presence of O2 and H2O involves a series of reactions that lead to the formation of SO3 and eventually H2SO4. Homogeneous experiments were conducted to evaluate the effects of the procedural variables, i.e., temperature, gas concentrations, and residence time, on the post-combustion conversion of SO2 to SO3. The results were compared to existing global kinetics and found to be dependent upon SO2, O2, residence time, and temperature and independent of H2O content. For a residence time of 1 s, temperatures of about 900 °C are needed to have an observable conversion of SO2 to SO3. Literature suggested that the conversion of SO2 to SO3 is dependent upon the iron oxide content of the fly ash. Experiments using three different fly ash samples from Australian sub-bituminous coals were used to investigate the catalytic effects of fly ash on SO2 conversion to SO3 at a temperature range of 400-1000 °C. It was observed that fly ash acts as a catalyst in the formation of SO3, with the largest conversion occurring at 700 °C. A homogeneous reaction at 700 °C, without fly ash present, converted 0.10% of the available SO2 to SO3. When fly ash was present, the conversion increased to 1.78%. The catalytic effect accounts for roughly 95% of the total conversion. Average SO3/SO2 conversion values between fly ash derived from air and oxy-fuel firing and under different flue gas environments were found to be similar.
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Nova |
2014 |
Liu D, Liu Y, Wall T, 'CO2 quality control in oxy-fuel combustion: A dynamic study on the absorption of SO2 into sodium based aqueous solutions relevant to scrubbing prior to CO2 compression (vol 12, pg 2, 2012)', INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, 22 329-329 (2014)
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Nova |
2014 |
Liu D, Liu Y, Wall T, Stanger R, 'CO2 quality control by scrubbing in oxy-fuel combustion prior to compression: Relating pH to the liquid composition from absorption of SO2 into sodium based solutions to identify an operational pH window (vol 19C, pg 462, 2013)', INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, 22 330-330 (2014)
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Nova |
2014 |
Ting T, Stanger R, Wall T, 'Oxyfuel CO
Oxyfuel flue gas contains trace amounts of elemental mercury, which may corrode brazed aluminium heat exchangers used in the carbon dioxide purification system. International gas ... [more]
Oxyfuel flue gas contains trace amounts of elemental mercury, which may corrode brazed aluminium heat exchangers used in the carbon dioxide purification system. International gas vendors have tested the use of the compression system to remove other flue gas impurities such as NOx; however, the reaction mechanism of mercury and its reaction products with NOx and nitric acid formed with condensed water vapour are unclear. This study used lab scale experiments to study the absorption of gaseous elemental mercury into nitric acid and the gas phase reaction between mercury and nitrogen dioxide formed from oxidised NO at pressures up to 25bar. It was observed that mercury has limited absorption into nitric acid and may partially desorb out of solution after depressurisation. On the other hand, mercury reacted readily with nitrogen dioxide (formed from nitric oxide oxidation at high pressure) in the gas phase. These gas phase reactions from the oxidation of nitric oxide to nitrogen dioxide to the subsequent oxidation of elemental mercury by nitrogen dioxide were predicted using existing global kinetic equations. The limited absorption of gaseous elemental mercury in nitric acid and significant oxidation of gaseous elemental mercury by nitrogen dioxide suggests that the primary removal step for elemental mercury is through the gas phase reaction. Oxyfuel compression circuits should therefore allow sufficient residence time for this gas phase reaction to occur. © 2014 Elsevier Ltd.
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Nova |
2014 |
Stanger R, Xie W, Wall T, Lucas J, Mahoney M, 'Dynamic measurement of coal thermal properties and elemental composition of volatile matter during coal pyrolysis', Journal of Materials Research and Technology, 3 2-8 (2014) [C1]
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Nova |
2014 |
Stanger R, Ting T, Wall T, 'High pressure conversion of NO x and Hg and their capture as aqueous condensates in a laboratory piston-compressor simulating oxy-fuel CO 2 compression', International Journal of Greenhouse Gas Control, 29 209-220 (2014) [C1]
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Nova |
2013 |
Xie W, Stanger R, Lucas J, Wall T, Mahoney M, 'Coal macerals separation by reflux classification and thermo-swelling analysis based on the Computer Aided Thermal Analysis', FUEL, 103 1023-1031 (2013) [C1]
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Nova |
2013 |
Shah K, Moghtaderi B, Zanganeh J, Wall T, 'Integration options for novel chemical looping air separation (ICLAS) process for oxygen production in oxy-fuel coal fired power plants', FUEL, 107 356-370 (2013) [C1]
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Nova |
2013 |
Wall T, Stanger R, Liu Y, 'Gas cleaning challenges for coal-fired oxy-fuel technology with carbon capture and storage', FUEL, 108 85-90 (2013) [C1]
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Nova |
2013 |
Stanger R, Wall T, Lucas J, Mahoney M, 'Dynamic Elemental Thermal Analysis (DETA) - A characterisation technique for the production of biochar and bio-oil from biomass resources', FUEL, 108 656-667 (2013) [C1]
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Nova |
2013 |
Stanger R, Xie W, Wall T, Lucas J, Mahoney M, 'Dynamic Elemental Thermal Analysis: A technique for continuous measurement of carbon, hydrogen, oxygen chemistry of tar species evolved during coal pyrolysis', Fuel, 103 764-772 (2013) [C1]
A novel technique is described which provides quantitative and continuous analysis of light gas and condensable tar components as they are evolved in terms of carbon, hydrogen and... [more]
A novel technique is described which provides quantitative and continuous analysis of light gas and condensable tar components as they are evolved in terms of carbon, hydrogen and oxygen. The technique has also been used to directly characterise the total tar sample in terms of carbon distribution and boiling point. It has been found that changes to the dynamic tar-H/C ratio correspond well with particular temperatures measured by Geiseler Plastometer for softening, maximum fluidity and re-solidification. This technique can enhance the chemical understanding of mechanisms occurring during de-polymerisation and cross-linking of coal (i.e. metaplast development and the transfer of hydrogen) while also monitoring tar evolution. A tar collection and re-vaporisation method provides a means of identifying tar groups that contribute towards the metaplast phase and temperatures at which they evolve. Both methods are unique in studying chemical aspects of coal and tar behaviour with heating, in a field based on thermo-physical techniques (e.g. H1 NMR, high temperature rheology, Geiseler plastometry, dilatation). Overall, the Dynamic Elemental Thermal Analysis (DETA) technique can give new insight into the fundamental mechanisms prevalent in coal pyrolysis and provides quantitative chemical assessment of tar nature (i) during the heating of coal and (ii) as a final (total) condensed product. © 2012 Elsevier Ltd. All rights reserved.
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Nova |
2013 |
Shah K, Moghtaderi B, Wall T, 'Effect of flue gas impurities on the performance of a chemical looping based air separation process for oxy-fuel combustion', Fuel, 103 932-942 (2013) [C1]
Integrated Chemical Looping Air Separation (ICLAS) offers an energy efficient and cost effective option for large-scale oxygen generation in oxy-fuel type power plants. Oxygen pro... [more]
Integrated Chemical Looping Air Separation (ICLAS) offers an energy efficient and cost effective option for large-scale oxygen generation in oxy-fuel type power plants. Oxygen production in the ICLAS is achieved by reduction of oxidised metal oxides in an environment of steam/recycled flue gas (CO2-rich) using a dedicated reduction reactor. This paper provides the results of a thermodynamic investigation into the effect of flue gas impurities on the reduction of three metal oxide oxygen carriers (Cu, Mn and Co oxides) under conditions pertinent to an oxy-fuel coal-fired power plant. Relevant calculations were carried out using the Fact-sage 6.1 thermodynamic equilibrium calculation software package. Different gas streams, namely crude/wet, dry, pure CO2 and steam were considered in the simulations together with the additional hypothetical impure flue gas stream having larger concentrations of CO, SO2 and NO. Effects of SO2, NO, CO and O2 contents of the flue gas on oxygen carrier conversion and oxygen decoupling process were investigated in detail. It was established that the successful reduction of metal oxides in the presence of flue gas impurities can only be achieved at higher temperatures due to increased partial pressure of O2 and the formation of metal sulphates at temperatures less than 800-900 °C. This may increase the operating and capital costs of the CLAS based oxygen production. © 2012 Elsevier Ltd. All rights reserved.
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Nova |
2013 |
Stanger R, Xie W, Wall T, Lucas J, Mahoney M, 'Dynamic behaviour of coal macerals during pyrolysis-Associations between physical, thermal and chemical changes', Proceedings of the Combustion Institute, 34 2393-2400 (2013) [C1]
A fundamental study on the behaviour of heating coal macerals has been undertaken using two novel thermal analysis techniques. The apparent specific heat was determined during hea... [more]
A fundamental study on the behaviour of heating coal macerals has been undertaken using two novel thermal analysis techniques. The apparent specific heat was determined during heating using an inverse calorimetric method (computer aided thermal analysis, CATA) and combined with pressure and displacement measurements to correlate endothermic and exothermic behaviour with measurement of swelling. The second technique used a post-oxidation stage to combust the tars and gases into products which were analysed. This method was used to study the elemental character of volatiles release from coal maceral concentrates in terms of carbon and hydrogen. Extents of swelling and exothermicity during primary devolatilisation were found to be correlated with vitrinite content and were associated with tar evolution. For the highest vitrinite fraction (of 86.4% vitrinite) swelling was initiated at the same temperature range for exothermic reactions, and maximum swelling coincided with the peak release of light gases. Tar evolution was found to change in chemical character (as defined by H/C ratio) during progressive heating, initially rising in the early stages of tar formation (<430°C) to a maximum of 1.24, then gradually decreasing to a minimum of 0.64 at 550°C. © 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
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Nova |
2013 |
Liu D, Liu Y, Wall T, 'CO2 quality control in oxy-fuel combustion: A dynamic study on the absorption of SO2 into sodium based aqueous solutions relevant to scrubbing prior to CO2 compression', INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, 12 2-8 (2013) [C1]
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Nova |
2013 |
Ting T, Stanger R, Wall T, 'Laboratory investigation of high pressure NO oxidation to NO
Oxyfuel combustion enables carbon dioxide capture for storage and can therefore significantly reduce carbon dioxide emissions from coal fired power plants. However, CO2 derived fr... [more]
Oxyfuel combustion enables carbon dioxide capture for storage and can therefore significantly reduce carbon dioxide emissions from coal fired power plants. However, CO2 derived from oxyfuel combustion has impurities that cause corrosion to plant equipment and transport lines and may be subjected to certain storage and end user requirements. The use of the CO2 compression system in an oxyfuel power plant to remove these impurities has been proposed and tested by international gas vendors both at laboratory and power-plant scale; however the extent of quantitative removal of these impurities by the compression system is unknown. The current research uses laboratory experiments to study the reactions of nitrogen oxides in the compression system. These include the oxidation of NO to NO2 in the gas phase, the absorption in liquid water and also reactions with water vapour in conditions from ambient conditions to pressures of 30bar. The reactor used was a bubble column that was preloaded with liquid water. Results show that nitric oxide is readily oxidised to water-soluble nitrogen dioxide at elevated pressures. This reaction is kinetically controlled and can be predicted using an equation derived for atmospheric pressure conditions. The resulting nitrogen dioxide is shown to react with liquid water to form nitrous and nitric acid. Single experiments also showed the potential for gas phase acid formation and condensation. Overall mass balances across the gas-liquid system were complicated by the stability of the absorbed NOx species in the liquid. © 2013 Elsevier Ltd.
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Nova |
2013 |
Liu D, Liu Y, Wall T, Stanger R, 'CO
Oxy-fuel combustion is an emerging technology to mitigate CO2 emissions from power plants. Compared with other CO2 capture technologies, gas impurities in oxy-fuel flue gas are hi... [more]
Oxy-fuel combustion is an emerging technology to mitigate CO2 emissions from power plants. Compared with other CO2 capture technologies, gas impurities in oxy-fuel flue gas are highly concentrated, among which SO2 is of concern. Sodium based quench units have been used in oxyfuel projects to directly cool the gas prior to compression and to also remove SO2. However, the high concentration of CO2 in the flue gas can interfere with the capture of SO2. Dynamic transient experiments were therefore conducted in a semi-batch well stirred reactor (WSR) to study the mechanisms of SO2 absorption from gas mixtures of both SO2/N2 and SO2/CO2 into sodium based aqueous solutions, with measurements of SO2 absorption rate and decreasing liquid pH during the experiments. The liquids were analysed by ion chromatography (IC) and acid titration with equilibrium calculations to estimate sulfur and carbon species formed in the liquid.The dynamic absorption results for SO2/CO2 show three pH regions of absorption behaviour as pH reduced during the experiments, namely, region 1 with a constant gas absorption rate at pH values above 8.32 (this being 9.65 for the SO2/N2 experiments); region 2 where the gas absorption rate reduced at pH values from 8.32 to 4.22 (from 9.65 to 4.82 for SO2/N2); and region 3 where gas absorption reduced rapidly with pH, at pH values below 4.22 (4.82 for SO2/N2). From liquid analyses and thermodynamic calculations it is concluded that region 1 is associated with the consumption of OH- to give SO32-, region 2 with the consumption of HCO3-/SO32- and the formation of HSO3-, and region 3 with the consumption of H2O and the accumulation of HSO3- and SO2.The operational pH of the sodium based quench units is recommended to be in region 2, where a high absorption rate of SO2 and low sodium loss are expected. An operational pH window is thereby defined in terms of upper and lower limits. The operational pH window is found to be related to the concentration of sodium solutions when an inlet concentration of SO2 is proximately 3000ppm, and the window narrows at high concentrations of sodium solutions. The operational window is secondarily related with the concentrations of SO2 and narrows at low concentrations of SO2. © 2013 Elsevier Ltd.
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Nova |
2012 |
Cao H, Sun S, Chen H, Meng X, Wang D, Wall TF, 'Experimental study of volatile-N conversion at O-2/CO2 atmosphere in a drop tube furnace', CLEANER COMBUSTION AND SUSTAINABLE WORLD, 257-260 (2012) |
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2012 |
Shah KV, Moghtaderi B, Wall TF, 'Selection of suitable oxygen carriers for chemical looping air separation: A thermodynamic approach', Energy & Fuels, 26 2038-2045 (2012) [C1]
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Nova |
2012 |
Li H, Elliott LK, Rogers HP, Austin P, Jin Y, Wall TF, 'Reactivity study of two coal chars produced in a drop-tube furnace and a pulverized coal injection rig', Energy and Fuels, 26 4690-4695 (2012) [C1]
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Nova |
2011 |
Sun S, Cao H, Chen H, Wang X, Qian J, Wall TF, 'Experimental study of influence of temperature on fuel-N conversion and recycle NO reduction in oxyfuel combustion', Proceedings of the Combustion Institute, 33 1731-1738 (2011) [C1]
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Nova |
2011 |
Santos S, Anheden M, Kather A, Wall T, Wendt J, Yan J, 'Oxyfuel Combustion Technology - Working Toward Demonstration and Commercialisation Preface', INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, 5 S1-S1 (2011) [C3]
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2011 |
Wall TF, Stanger RJ, Santos S, 'Demonstrations of coal-fired oxy-fuel technology for carbon capture and storage and issues with commercial deployment', International Journal of Greenhouse Gas Control, 5 S5-S15 (2011) [C1]
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Nova |
2011 |
Stanger RJ, Wall TF, 'Sulphur impacts during pulverised coal combustion in oxy-fuel technology for carbon capture and storage', Progress in Energy and Combustion Science, 37 69-88 (2011) [C1]
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Nova |
2010 |
Xie W, Chang L, Wang D, Xie K, Wall TF, Yu J, 'Removal of sulfur at high temperatures using iron-based sorbents supported on fine coal ash', Fuel, 89 868-873 (2010) [C1]
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Nova |
2010 |
Wall TF, Yu J, 'Special issue of Fuel on 'The 7th International Symposium on Gas Cleaning at High Temperatures (GCHT-7)'', Fuel, 89 803 (2010) [C3]
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2010 |
Cao H, Sun S, Liu Y, Wall TF, 'Computational fluid dynamics modeling of NOx reduction mechanism in oxy-fuel combustion', Energy & Fuels, 24 131-135 (2010) [C1]
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Nova |
2010 |
Li X, Rathnam RK, Yu JL, Wang Q, Wall TF, Meesri C, 'Pyrolysis and combustion characteristics of an indonesian low-rank coal under O2/N2 and O2/CO2 conditions', Energy & Fuels, 24 160-164 (2010) [C1]
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Nova |
2009 |
Wall TF, Liu Y, Spero C, Elliott LK, Khare S, Rathnam RK, et al., 'An overview on oxyfuel coal combustion: State of the art research and technology development', Chemical Engineering Research and Design, 87 1003-1016 (2009) [C1]
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Nova |
2009 |
Rathnam RK, Elliott LK, Wall TF, Liu Y, Moghtaderi B, 'Differences in reactivity of pulverised coal in air (O-2/N-2) and oxy-fuel (O-2/CO2) conditions', Fuel Processing Technology, 90 797-802 (2009) [C1]
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Nova |
2009 |
Gupta S, Gupta R, Bryant GW, Wall TF, Watanabe S, Kiga T, Narukawa K, 'Characterization of ash deposition and heat transfer behavior of coals during combustion in a pilot-scale facility and full-scale utility', Energy & Fuels, 23 2570-2575 (2009) [C1]
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Nova |
2009 |
Li X, Song H, Wang Q, Meesri C, Wall TF, Yu J, 'Experimental study on drying and moisture re-adsorption kinetics of an Indonesian low rank coal', Journal of Environmental Sciences, 21 S127-S130 (2009) [C1]
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Nova |
2008 |
Khare S, Wall TF, Farida AZ, Liu Y, Moghtaderi B, Gupta RP, 'Factors influencing the ignition of flames from air-fired swirl pf burners retrofitted to oxy-fuel', Fuel, 87 1042-1049 (2008) [C1]
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Nova |
2008 |
Hinkley JT, Bridgman HA, Buhre BJ, Gupta RP, Nelson PF, Wall TF, 'Semi-quantitative characterisation of ambient ultrafine aerosols resulting from emissions of coal fired power stations', Science of the Total Environment, 391 104-113 (2008) [C1]
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Nova |
2008 |
Elliott LK, Lucas JA, Happ J, Patterson J, Hurst H, Wall TF, 'Rate limitations of lime dissolution into coal ash slag', Energy & Fuels, 22 3626-3630 (2008) [C1]
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Nova |
2007 |
Buhre BJ, Hinkley JT, Gupta RP, Nelson P, Wall TF, 'Factors affecting the vaporisation of silica during coal combustion', Fuel Processing Technology, 88 157-164 (2007) [C1]
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2007 |
Tortosa Masia AA, Buhre BJ, Gupta RP, Wall TF, 'Characterising ash of biomass and waste', Fuel Processing Technology, 88 1071-1081 (2007) [C1]
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2007 |
Nutalapati DB, Gupta R, Moghtaderi B, Wall TF, 'Assessing slagging and fouling during biomass combustion: A thermodynamic approach allowing for alkali/ash reactions', Fuel Processing Technology, 88 1044-1052 (2007) [C1]
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2007 |
Liu Y, Gupta R, Elliott LK, Wall TF, Fujimori T, 'Thermomechanical analysis of laboratory ash, combustion ash and deposits from coal combustion', Fuel Processing Technology, 88 1099-1107 (2007) [C1]
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2007 |
Harding S, Wall TF, Wigley F, Frandsen F, Hupa M, Tillman D, 'Foreword', Fuel Processing Technology, 88 1009 (2007) [C3]
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2007 |
Harding S, Wall TF, Wigley F, Frandsen F, Hupa M, Tillman D, 'Impacts of fuel quality on power production - Foreword', Fuel Processing Technology, 88 1009 (2007) [C3]
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2007 |
Liu Y, Gupta R, Wall TF, 'Ash formation from excluded minerals including consideration of mineral-mineral associations', Energy & Fuels, 21 461-467 (2007) [C1]
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2007 |
Xie W, Chang L, Song H, Liu X, Xie K, Wall T, Yu J, 'Two-step hot coal gas desulphurization process integrated with direct production of elemental sulfur using iron-based sorbents: A preliminary study', 24th Annual International Pittsburgh Coal Conference 2007, PCC 2007, 1 544-553 (2007)
The paper proposed a two-step desulphurization process using iron-based high temperature sorbents for removal of hydrogen sulfide from hot coal gases after coal gasification. The ... [more]
The paper proposed a two-step desulphurization process using iron-based high temperature sorbents for removal of hydrogen sulfide from hot coal gases after coal gasification. The authors use the mixture of iron oxide with other metal oxides (e.g. Ce) supported by ash from a coalgangue- fired power plant to prepare high temperature desulphurization sorbents. The two-step desulphurization process is comprised of a first-stage desulphurization of removing majority of sulfur followed by a second-stage desulphurization to remove the remaining sulfur species. The process is integrated with effective sulfur recovery through direct elemental sulfur production during the regeneration of Fe/Ce based sorbents. Preliminary studies on sulfidation using a quartz fixed-bed reactor demonstrated that the Fe/Ce-based sorbents prepared in this study was able to remove >97% sulfur in the temperature range of 400-600°C. Simultaneous removal of organic and inorganic sulfur species was achieved.
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2007 |
Yu J, Lucas JA, Wall TF, 'Formation of the structure of chars during devolatilization of pulverized coal and its thermoproperties: A review', Progress in Energy and Combustion Science, 33 135-170 (2007) [C1]
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2007 |
Wall TF, 'Combustion processes for carbon capture', Proceedings of the Combustion Institute, 31 31-47 (2007) [C1]
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2007 |
Masia AAT, Buhre BJ, Gupta RP, Wall TF, 'Use of TMA to predict deposition behaviour of biomass fuels', Fuel, 86 2446-2456 (2007) [C1]
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2006 |
Zulfiqar MH, Moghtaderi B, Wall TF, 'Flow properties of biomass and coal blends', Fuel Processing Technology, 87 281-288 (2006) [C1]
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2006 |
Moghtaderi B, Sheng C, Wall TF, 'An Overview of the Australian Biomass Resources and Utilization Technologies', BioResources, 1 93-115 (2006) [C1]
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2006 |
Buhre BJ, Hinkley JT, Gupta RP, Nelson PF, Wall TF, 'Fine ash formation during combustion of pulverised coal-coal property impacts', Fuel, 85 185-193 (2006) [C1]
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Nova |
2005 |
Tang L, Gupta RP, Sheng C, Wall TF, 'The char structure characterization from the coal reflectogram', Fuel, 84 1268-1276 (2005) [C1]
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2005 |
Strezov V, Lucas JA, Wall TF, 'Effect of pressure on the swelling of density separated coal particles', Fuel, 84 1238-1245 (2005) [C1]
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2005 |
Tang L, Gupta RP, Sheng C, Wall TF, 'The estimation of char reactivity from coal reflectogram', Fuel, 84 127-134 (2005) [C1]
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2005 |
Al-Otoom A, Elliott LK, Moghtaderi B, Wall TF, 'The sintering temperature of ash, agglomeration, and defluidisation in a bench scale PFBC', Fuel, 84 109-114 (2005) [C1]
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Nova |
2005 |
Liu Y, Gupta RP, Sharma A, Wall TF, Butcher A, Miller G, et al., 'Mineral matter-organic matter association characterisation by QEMSCAN and applications in coal utilisation', Fuel, 84 1259-1267 (2005) [C1]
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Nova |
2005 |
Matsuoka K, Akiho H, Xu W-C, Gupta RP, Wall TF, Tomita A, 'The physical character of coal char formed during rapid pyrolysis at high pressure', Fuel, 84 63-69 (2005) [C1]
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Nova |
2005 |
Buhre BJ, Hinkley JT, Gupta RP, Wall TF, Nelson PF, 'Submicron ash formation from coal combustion', Fuel, 84 1206-1214 (2005) [C1]
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Nova |
2005 |
Buhre BJ, Elliott LK, Sheng C, Gupta RP, Wall TF, 'Oxy-fuel combustion technology for coal-fired power generation', Progress in Energy and Combustion Science, 31 283-307 (2005) [C1]
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Nova |
2005 |
Wu H, Zhang DK, Kong C, Wall TF, 'Ash formation from the combustion of coals with maceral concentrates at various pressures', Developments in Chemical Engineering and Mineral Processing, 13 415-422 (2005) [C1]
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2005 |
Tang L, Gupta RP, Sheng C, Wall TF, O'Brien G, 'The heterogeneity of coal chemical properties derived from a reflectogram', Energy & Fuels, 19 130-137 (2005) [C1]
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2005 |
Buhre BJ, Browning GJ, Gupta RP, Wall TF, 'Measurement of the viscosity of coal-derived slag using thermomechanical analysis', Energy & Fuels, 19 1078-1083 (2005) [C1]
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Nova |
2005 |
Gupta RP, Yan L, Gupta SK, Wall TF, Kiga T, Watanabe S, 'CCSEM Analysis of Minerals in Coal and Thermal Performance of pc-Fired Boilers', Clean Air: International Journal on Environmental Combustion Technologies, 6 157-170 (2005) [C1]
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2005 |
Cetin E, Moghtaderi B, Gupta RP, Wall TF, 'Biomass gasification kinetics: Influences of pressure and char structure', Combustion Science and Technology, 177 765-791 (2005) [C1]
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Nova |
2005 |
Zheng L, Tan Y, Wall T, 'Some thoughts and observations on oxy-fuel technology developments', 22nd Annual International Pittsburgh Coal Conference 2005, PCC 2005, 1 908-917 (2005)
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2004 |
Yu J, Lucas JA, Wall TF, Liu G, Sheng C, 'Modelling the development of char structure during the rapid heating of pulverized coal', Combustion and Flame, 136 519-532 (2004) [C1]
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2004 |
Miura K, Benson SA, Wall TF, 'Preface to special issue on clean coal technology', Fuel, 83 629 (2004) [C1]
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2004 |
Moghtaderi B, Meesri C, Wall TF, 'Pyrolytic characteristics of blended coal and woody biomass', Fuel, 83 745-750 (2004) [C1]
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Nova |
2004 |
Sheng C, Moghtaderi B, Gupta RP, Wall TF, 'A computational fluid dynamics based study of the combustion characteristics of coal blends in pulverised coal-fired furnace', Fuel, 83 1543-1552 (2004) [C1]
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2004 |
Cetin E, Moghtaderi B, Wall TF, 'Influence of pyrolysis conditions on the structure and gasification reactivity of biomass chars', Fuel, 83 2139-2150 (2004) [C1]
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Nova |
2004 |
Yu J, Harris D, Lucas JA, Roberts D, Wu H, Wall TF, 'Effect of Pressure on Char Formation during Pyrolysis of Pulverized Coal', Energy & Fuels, 18 1346-1353 (2004) [C1]
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2004 |
Tang L, Gupta RP, Sheng C, Wall TF, 'A Mechanistic Approach To Characterize Coal Hetrogeneity in Predicting High-Temperature Volatile Matter Yields', Energy & Fuels, 18 1716-1722 (2004) [C1]
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2004 |
McLellan B, Diniz Da Costa JC, Dicks AL, Rudolph V, Pagan RJ, Sheng C, Wall TF, 'Hydrogen Economy Options for Australia', Developments in Chemical Engineering and Mineral Processing, 12(5/6) 447-460 (2004) [C1]
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2003 |
Yu J, Strezov V, Lucas JA, Wall TF, 'Swelling Behaviour of Individual Coal Particles in the Single Particle Reactor', Fuel, 82 1977-1987 (2003) [C1]
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2003 |
Yu J, Lucas JA, Strezov V, Wall TF, 'Coal and Carbon Nanotube Production', Fuel, 82 2025-2032 (2003) [C1]
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2003 |
Al-Otoom A, Ninomiya Y, Moghtaderi B, Wall TF, 'Coal Ash Buildup on Ceramic Filters in a Hot Gas Filtration System', Energy & Fuels, 17 316-320 (2003) [C1]
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2003 |
Roberts DG, Harris DJ, Wall TF, 'On the Effects of High Pressure and Heating Rate during Coal Pyrolysis on Char Gasification Reactivity', Energy & Fuels, 17 887-895 (2003) [C1]
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2003 |
Browning GJ, Bryant GW, Hurst HJ, Lucas JA, Wall TF, 'An Empirical Method for the Prediction of Coal Ash Slag Viscosity', Energy & Fuels, 17 731-737 (2003) [C1]
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2003 |
Yu J, Lucas JA, Strezov V, Wall TF, 'Swelling and Char Structures from Density Fractions of Pulverized Coal', Energy & Fuels, 17 1160-1174 (2003) [C1]
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2002 |
Yan L, Gupta RP, Wall TF, 'A mathematical model of ash formation during pulverized coal combustion', Fuel, 81 337-344 (2002) [C1]
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2002 |
Yu JL, Strezov V, Lucas JA, Liu GL, Wall TF, 'A mechanistic study on char structure evolution during coal devolatilization - experiments and model predictions', Proceedings of the Combustion Institute, 29 1-7 (2002) [C1] |
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2002 |
Yu JL, Strezov V, Lucas J, Liu GS, Wall T, 'A mechanistic study on char structure evolution during coal devolatilization - Experiments and model predictions', Proceedings of the Combustion Institute, 29 467-473 (2002)
Char structures evolved during the devolatilization process have been found to play a significant role in the subsequent processes (e.g., char combustion and gasification) and to ... [more]
Char structures evolved during the devolatilization process have been found to play a significant role in the subsequent processes (e.g., char combustion and gasification) and to influence the ash formation mechanisms. In the present paper, a mathematical model has been developed based on the multibubble mechanism to simulate the char structure evolution process. The model is the first to provide predictions of heterogenous char structures evolved during devolatilization (e.g. cenospheric char, foam structure, or dense char structure) as well as transient particle swelling ratios, based on the ultimate and proximate data of the given coal. The devolatilization process is divided into the preplastic stage, plastic stage, and resolidified stage. Bubble number conservation, mass, and force balance are formulated during the plastic stage to predict the transient swelling ratio and resultant char structures. Experiments have been conducted using a single coal particle reactor (SPR) and a drop tube furnace (DTF) with density-separated coal samples prepared using the sink-float method. The SPR experiments confirm that bubble behavior is responsible for the swelling of the particles that develop plasticity on heating. The analysis of the DTF chars shows that the swelling ratio and porosity decrease with increasing the coal density. Chars from lowdensity samples are mainly Group I chars (porosity >80%), while high-density samples yield mainly Group III chars (porosity <50%), and the medium-density samples contain a mixture. The predicted swelling ratio, porosity, and char type distribution of the chars of the density-separated samples are consistent with the experimental data.
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2002 |
Wall TF, Liu G, Wu H, Roberts DG, Benfell KE, Lucas JA, et al., 'The effects of pressure on coal reactions during pulverised coal combustion and gasification', Progress in Energy and Combustion Science, 28 405-433 (2002) [C1]
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Nova |
2001 |
Yan L, Gupta R, Wall T, 'Fragmentation behavior of pyrite and calcite during high-temperature processing and mathematical simulation', ENERGY & FUELS, 15 389-394 (2001)
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2001 |
Yan L, Gupta RP, Wall TF, 'The implication of mineral coalescence behaviour on ash formation and ash deposition during pulverised coal combustion', Fuel, 80 1333-1340 (2001) [C1]
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2001 |
Yan L, Gupta RP, Wall TF, 'Fragmentation behaviour of pyrite and calcite during high temperature processing and mathematical simulation', Energy & Fuels, 15 384-394 (2001) [C1] |
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2001 |
Wall TF, Liu G, Wu H, Benfell K, 'The effect of pressure on char characteristics, burnout and ash formation in entrained flow gasifiers', IFRF Combustion Journal, 2001 www.ifrf.net/journal (2001) [C1] |
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2000 |
Liu G, Benyon P, Benfell KE, Bryant GW, Tate AG, Boyd RK, et al., 'The porous structure of bituminous coal chars and its influence on combustion and gasification under chemically controlled conditions', Fuel, 79 617-626 (2000) [C1]
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2000 |
Liu G, Tate AG, Bryant GW, Wall TF, 'Mathematical modelling of coal char reactivity with CO2 at high prerssures and temperatures', Fuel, 79 1145-1154 (2000) [C1]
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2000 |
Liu G, Rezaei H, Lucas JA, Harris DJ, Wall TF, 'Modelling of a pressurised entrained flow coal gasifier: the effect of reaction kinetics and char structure', Fuel, 79 1767-1779 (2000) [C1]
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2000 |
Rezaei H, Gupta RP, Bryant GW, Hart JT, Liu GS, Bailey CW, et al., 'Thermal conductivity of coal ash and slags and models used', Fuel, 79 1697-1710 (2000) [C1]
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2000 |
Liu G, Wu H, Gupta RP, Lucas JA, Tate AG, Wall TF, 'Modelling the fragmentation of non-uniform porous char particles during pulverised coal combustion', Fuel, 79 627-633 (2000) [C1]
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2000 |
Roberts DG, Harris DJ, Wall TF, 'Total pressure effects on chemical reaction rated with O2, CO2 and H2O', Fuel, 79 1997-1998 (2000) [C3]
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2000 |
Al-Otoom A, Elliott LK, Wall TF, Moghtaderi B, 'Measurements of the sintering kinetics of coal ash', Energy & Fuels, 14 994-1001 (2000) [C1]
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2000 |
McLennan AR, Bryant GW, Bailey CW, Stanmore BR, Wall TF, 'An experimental comparison of the ash formed from coals containing pyrite and siderite mineral in oxidizing and reducing conditions', Energy & Fuels, 14 308-315 (2000) [C1]
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2000 |
McLennan AR, Bryant GW, Bailey CW, Stanmore BR, Wall TF, 'Index for iron-based slagging for pulverized coal firing in oxidizing and reducing conditions', Energy & Fuels, 14 349-354 (2000) [C1]
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2000 |
Wu H, Bryant GW, Benfell KE, Wall TF, 'An experimental study on the effect of system pressure on char structure of an Australian bituminous coal', Energy & Fuels, 14 282-290 (2000) [C1]
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2000 |
Bryant GW, Browning GJ, Gupta SK, Lucas JA, Gupta RP, Wall TF, 'Thermomechanical analysis of coal ash: the influence of the material for the sample assembly', Energy and Fuels, 14 326-335 (2000) [C1]
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2000 |
Bryant GW, Browning GJ, Emanuel H, Gupta SK, Gupta RP, Lucas JA, Wall TF, 'The fusibility of blended coal ash', Energy and Fuels, 14 316-325 (2000) [C1]
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2000 |
Al-Otoom A, Bryant GW, Elliott LK, Skrifars B, Hupa M, Wall TF, 'Experimental options for determining the temperature for the onset of sintering of coal ash', Energy and Fuels, 14 227-233 (2000) [C1]
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2000 |
McLennan AR, Bryant GW, Stanmore BR, Wall TF, 'Ash formation mechanisms during pf combustion in reducing conditions', Energy and Fuels, 14 150-159 (2000) [C1]
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2000 |
Wu H, Bryant GW, Wall TF, 'The effect of pressure on ash formation during pulverised coal combustion', Energy and Fuels, 14 745-750 (2000) [C1]
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2000 |
Benfell KE, Liu G-S, Roberts DG, Harris DJ, Lucas JA, Bailey JG, Wall TF, 'Modeling char combustion: The influence of parent coal petrography and pyrolysis pressure on the structure and intrinsic reactivity of its char', Proceedings of the Combustion Institute, 28 2233-2241 (2000)
Chars were made from four Australian coals of varying vitrinite content at pressures of 5, 10, and 15 atm. The morphology of the chars was correlated with the petrography of the p... [more]
Chars were made from four Australian coals of varying vitrinite content at pressures of 5, 10, and 15 atm. The morphology of the chars was correlated with the petrography of the parent coal. The intrinsic reaction rates of the chars at high pressures were measured, and no systematic effect of pyrolysis pressure or maceral concentration was found. It is concluded that observed variations in conversion rates under process conditions are likely to be due to char structural properties and not a result of variation in the intrinsic reactivity of the carbon in the chars. Consequently, this paper presents a char structural submodel that is integrated into an existing char combustion model to account for the combustion behavior of char particles of different morphologies. The char morphology used in the model was predicted using the developed correlation with parent coal petrography, so that a petrographic analysis as well as the proximate and ultimate analyses is required for model input. Validation of the model shows that chars produced at high pressure with a high percentage of cenospherical types burn more rapidly under process conditions than those at low pressure, with model predictions matching measurements. It is suggested that incorporating the char structural submodel into the existing char combustion model improves its predictability.
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1999 |
Bhattacharya SP, Wall TF, 'Development of emittance of coal particles during devolatilisation and burnoff', Fuel, 78 511-519 (1999) [C1]
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1999 |
Wall TF, Gupta SK, Gupta RP, Sanders RH, Creelman RA, Bryant GW, 'False deformation temperatures for ash fusibility associated with the condition for ash preparation', Fuel, 78 1057-1063 (1999) [C1]
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1999 |
Wu H, Wall TF, Liu G, Bryant GW, 'Ash liberation from included minerals during combustion of pulverised coal: The relationship with coal structure and burnout', Energy and Fuels, 13 1197-1202 (1999) [C1]
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1999 |
Liu G, Tate AG, Rezaei H, Beath AC, Wall TF, 'Modelling of intra-particle C-CO2 reaction: An application of the random pore model', Journal of Developments in Chemical Engineering and Mineral Processing, 7(5/6) 525-530 (1999) [C1] |
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1999 |
Bailey CW, Bryant GW, Wall TF, 'Ash deposits in a coal-fired power station related to experimentally measured ash character', IFRF Combustion Journal, 19 (1999) [C1] |
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1999 |
Browning GJ, Bryant GW, Lucas JA, Wall TF, 'The effects of heterogeneous slag character on viscosity and slag flow in IGCC gasifiers', IFRF Combustion Journal, 10 (1999) [C1] |
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1998 |
Smoot LD, Douglas Smoot L, Azevedo JLT, Costa M, Carvalho MG, Brockway DJ, et al., 'International research centers' activities in coal combustion', Progress in Energy and Combustion Science, 24 409-501 (1998)
Consumption of fossil fuels (i.e., oil, gas, coal) is the major source (86%) for meeting the world's energy needs and is projected to be so for some time to come. Coal accoun... [more]
Consumption of fossil fuels (i.e., oil, gas, coal) is the major source (86%) for meeting the world's energy needs and is projected to be so for some time to come. Coal accounts for 73% of the world's recoverable reserves of fossil fuels. World consumption of coal is increasing, particularly in Asia. Yet, clean and efficient use of coal presents important research challenges. This paper provides a comparative review of thirteen combustion centers in eight nations, where each has significant research components devoted to coal. Other active combustion centers doing similar work are not included in this review for various reasons. Following an introduction, a section of this review is devoted to each of the thirteen participating centers. In these sections, mission, objectives, research program, representative accomplishments, and directions are addressed. Data are also provided relating to center history, budget, size, and areas of emphasis. Collectively, these centers expend about $72 million per year, conduct over 600 research projects involving 1500 researchers, interact with 700 organizations, and provide an estimated 1000 reports and manuscripts annually. Though centers vary substantially in years of existence, budget size, personnel, and otherwise, on average, centers have 22 years of experience, involve over 110 research personnel, spend over $5 million per year, and conduct nearly 50 projects. All centers are involved in experimental measurements and applications of computerized combustion models, all work on environmental issues, all do substantial work relating to coal combustion, and all work on transferring center technologies. However, research on other fuels, focus on processes and systems, and emerging technologies vary substantially among the participating centers. Directions for centers' research typically include increasing international activity, strong environmental focus, more work on biomass and waste materials, emerging coal energy technologies, and improvement in conversion efficiencies. © 1998 Elsevier Science Ltd. All rights reserved.
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1998 |
Bailey CW, Bryant GW, Matthews EM, Wall TF, 'Investigation of the High Temperature Behaviour of Excluded Siderite Grains during Pulverized Fuel Combustion', Energy & Fuels, 12 464-469 (1998) [C1]
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1998 |
Bryant GW, Lucas JA, Gupta SK, Wall TF, 'Use of Thermomechanical Anlaysis to Quantify the Flux Additions necessary for Slag Flow in Slagging Gasifiers Fired with Coal', Energy & Fuels, 12 257-261 (1998) [C1]
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1998 |
Gupta SK, Gupta RP, Bryant GW, Wall TF, 'The Effect of Potassium on the Fusibility of Coal Ashes with High Silica and Alumina Levels', Fuel, 77,No.11 1195-1201 (1998) [C1]
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1998 |
Vuthaluru HB, Vleeskens JM, Wall TF, 'Reducing Fouling from Brown Coals by Sodium-Binding Additives', Fuel Processing Technology, 55 161-173 (1998) [C1]
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1998 |
Vuthaluru HB, Wall TF, 'Ash Formation and Deposition from a Victorian Brown Coal - Modelling and Prevention', Fuel Processing Technology, 53 215-233 (1998) [C1]
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1998 |
Gupta SK, Wall TF, Creelman RA, Gupta RP, 'Ash Fusion Temperatures and the Transformations of Coal Ash Particles to Slag', Fuel Processing Technology, 56 33-43 (1998) [C1]
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1998 |
Elliott LK, Wang S, Wall TF, Novak F, Lucas JA, Hurst H, et al., 'Dissolution of Lime into Synthetic Coal Ash Slags', Fuel Processing Technology, 56 45-53 (1998) [C1]
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1998 |
Wall TF, Creelman RA, Gupta RP, Gupta SK, Coin C, Lowe A, 'Coal Ash Fusion Temperatures - New Characterization Techniques, and Implications for Slagging and Fouling', Progress in Energy & Combustion Science, 24 345-353 (1998) [C1]
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1998 |
Gupta RP, Wall TF, Kajigaya I, Miyamae S, Tsumita Y, 'Computer-Controlled Scanning Electron Microscopy of Minerals in Coal - Implications for Ash Deposition', Progress in Energy & Combustion Science, 24 523-543 (1998) [C1]
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1998 |
Hart JA, Wall TF, 'The Cooperative Research Centre for Black Coal Utilization', Progress in Energy and Combustion Science, 24 433-439 (1998) [C1] |
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1998 |
Liu GS, Tate AG, Rezaei H, Beath AC, Wall TF, 'Modelling of Intra-Particle C-CO2 Reaction: An Application of the Random Pore Model', The Australasian Research Journal, 7,Nos.3/4 525-536 (1998) [C1]
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1997 |
Bhattacharya SP, Wall TF, Arduini-Schuster M, 'A study on the importance of dependent radiative effects in determining the spectral and total emittance of particulate ash deposits in pulverised fuel fired furnaces', CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION, 36 423-432 (1997)
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1996 |
Wall TF, Creelman RA, Gupta R, Gupta S, 'Ash fusion temperatures and the transformations of coal ash particles to slag.', ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 211 109-FUEL (1996) |
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1996 |
Vuthaluru HB, Domazetis G, Wall TF, Vleeskens JM, 'Reducing fly ash deposition by pretreatment of brown coal: Effect of aluminium on ash character', FUEL PROCESSING TECHNOLOGY, 46 117-132 (1996)
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1996 |
Gupta S, Wall TF, Creelman RA, Gupta R, 'Ash fusion temperatures and the transformations of coal ash particles to slag', ACS Division of Fuel Chemistry, Preprints, 41 647-649 (1996)
A mechanistic study is detailed in which coal ash is heated with its shrinkage measured continuously up to a temperature of 1600°C. The temperatures corresponding to the rapid rat... [more]
A mechanistic study is detailed in which coal ash is heated with its shrinkage measured continuously up to a temperature of 1600°C. The temperatures corresponding to the rapid rate of shrinkage are shown to correspond to the formation of eutectics identified on phase diagrams. Samples were therefore heated to these temperatures, cooled rapidly and examined with an SEM to identify the associated chemical and physical changes. The progressive changes in the range of chemical analysis (from SEM), the extent of undissolved ash particles and porosity were then quantified and related to homogenisation, viscosity and ash fusion mechanisms.
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1996 |
Bhattacharya SP, Wall TF, Gupta RP, 'An analysis of the angular scatter measurement to determine the optical constants of coal and ashy materials', INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER, 23 809-821 (1996)
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1996 |
Galvin KP, Cork A, Wall TF, 'Droplet impaction with a substrate - The critical condition for detachment', COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 113 107-116 (1996)
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1996 |
Elliott L, Wang SM, Wall T, Novak F, Lucas J, Hurst H, et al., 'Dissolution of lime into synthetic coal ash slags', ACS Division of Fuel Chemistry, Preprints, 41 686-688 (1996)
One of the alternate processes presently being investigated to produce electrical power from coal is Integrated Gasification Combined Cycle (IGCC). The ash that remains when the c... [more]
One of the alternate processes presently being investigated to produce electrical power from coal is Integrated Gasification Combined Cycle (IGCC). The ash that remains when the coal is gasified in this process, is removed by granulating the molten ash at 1400 - 1500°C. To reduce the melting temperature of the coal ash to this level, a flux, usually limestone, is added with the coal to the gasifier. The rate of dissolution of the flux is uncertain. This paper reports the investigation of the rate of lime dissolution into synthetic coal ashes, consisting of SiO2, Al2O3 and CaO Results previously reported have shown that the free dissolution of fine particles (50-200µm) is mass transfer controlled. To investigate forced dissolution, a high temperature viscometer was used to rotate a cylinder of lime in the molten slag for a given period. At temperatures between 1450°C and 1650°C, reaction products of 3CaO.SiO2/3CaO.Al2O3, 2CaO.SiO2/3CaO.Al2O3/12CaO.7Al 2O3 form around the lime pellet The concentration gradient involved in the mass transfer was defined, and initial studies of the diffusion coefficients were completed.
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1994 |
Richards GH, Harb JN, Baxter LL, Bhattacharya S, Gupta RP, Wall TF, 'Radiative heat transfer in pulverized-coal-fired boilers-Development of the absorptive/reflective character of initial ash deposits', Symposium (International) on Combustion, 25 511-518 (1994)
Emission Fourier transform, infrare (FTIR) spectroscopy data provide in situ, time-resolved, spectralemissivity measurements for ash deposits generated from two U.S. Powder River ... [more]
Emission Fourier transform, infrare (FTIR) spectroscopy data provide in situ, time-resolved, spectralemissivity measurements for ash deposits generated from two U.S. Powder River Basin coals. The first 3h of deposit growth on a tube in cross flow in a pilot-scale furnace detail the development of surface emissivity with time. Measured emissivities vary significantly with wavelength, indicating the influence of the physical properties and chemical composition of the deposit. At long wavelength (>7 µm), emission features exhibit characteristics of silica, sulfates, and silicates. The spectral emissivity measured in this region approaches a steady value due to an increase in deposit thickness and the size of particles in the deposit. In contrast, deposits are not opaque at shorter wavelengths where the measured emissivity is influenced by the properties of the underlying metal surface. Theoretical predictions of the emsivity of a particulate layer were performed, and results are compared to the measured values. The theory adequately predicts the general features of spectral variation of the emissivity. The predicted trends in emissivity with particle size and deposit composition are also consistent with exerimental observations. Total (Planck-weighted) emissivities are calculated from the measured spectral values for the deposits at the tube temperatures. They increase with time from the clean tube value (0.2-0.3) to values typicals of deposits formed from western U.S. coal (0.45-0.55). Calculated total absorptivities are found to be lower than the correspoding emissivities. © 1994 Combustion Institute.
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1994 |
ZHANG DK, WALL TF, HILLS PC, 'THE IGNITION OF SINGLE PULVERIZED COAL PARTICLES - MINIMUM LASER POWER REQUIRED', FUEL, 73 647-655 (1994)
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1994 |
ZHANG DK, LI T, COTTERILL GF, OCONNOR DJ, WALL TF, 'STM EXAMINATION OF O-2 ETCHING ON GRAPHITE SURFACES IN AIR', FUEL, 73 1372-1372 (1994)
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1994 |
Lucas JA, Wall TF, 'Volatile matter release, particle/cloud ignition, and combustion of near-stoichiometric suspensions of pulverised coal', Symposium (International) on Combustion, 25 485-491 (1994)
The ignition characteristics of a cloud of pulverised coal flowing in a drop-tube furnace are examined.Cloud ignition is defined at the minimum gas temperature at which significan... [more]
The ignition characteristics of a cloud of pulverised coal flowing in a drop-tube furnace are examined.Cloud ignition is defined at the minimum gas temperature at which significant oxygen consumption occurs. This is accompanied by the generation of carbon dioxide and oxides of nitrogen, and the formation of a visual flame. Cloud ignition occurs at several hundred degrees above that for the ignition of some single coal particles. For three coals the cloud ignition temperature decreased with oxygen partial pressure, but was not sensitive to fuel equivalence ratio or particle size (as has been observed for single particles). For the three coals examined, pyrolysis measurements show the existence of a tar/light hydrocarbon/oxygenmixture at the cloud ignition temperature. On combustion the accompanying temperature increase results in coal burnoffs from 35 to 65% even though the combustible volatile matter prior to the ignition event corresponds to less than 6.5% burnoff. Different trends of tar and methane combustion and soot formation are observed in the experiments as gas temperature and oxygen levels were changed; however, significant tar combustion was always observed at cloud ignition. A mechanistic model is proposed to explain the observations. © 1994 Combustion Institute.
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1994 |
Wall TF, Baxter LL, Richargs G, Harb JN, 'Ash deposits, coal blends and the thermal performance of furnaces 453-463 (1994)
The character of fireside ash deposites depend on the propocesses by which deposits are formed and subsequent reactions within the deposit and with furnancegases. The properties i... [more]
The character of fireside ash deposites depend on the propocesses by which deposits are formed and subsequent reactions within the deposit and with furnancegases. The properties influencing furnance heat transfer. absorptivity for radiative transfer and thermal conductivity for conductive transfer are shown from many measurements to dependent on this character. Illustrative trends in these properties as deposits mature and grow are presented together with their effect on furnance exit temperature and efficiency. The reflective character of initial deposits from particular coals is then considered with predictions and measurements of the spectral character of such deposits, during the first three hours of growth, using on-line FTIR spectroscopy.
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1994 |
Wall TF, Vuthaluru HB, Bryant G, Gupta RP, Domazetis G, 'Modifications ofm ash character and deposition of a brown coal by treatments and additives 355-373 (1994)
Experimental studies are detailed which examine the control of sodium based fouling and slagging of a Victorian brown coal. The ash forming elements namely-Na, Mg, Ca, Fe, Al, Cl,... [more]
Experimental studies are detailed which examine the control of sodium based fouling and slagging of a Victorian brown coal. The ash forming elements namely-Na, Mg, Ca, Fe, Al, Cl, and S in the particular coal-are bound within the coal matrix to oxygenated functional groups. The coal also contains discrete 8 to 80 micrometers mineral particles of silica. The coal was firstly treated to adjust levels of Na, Cl and Al by (a) washing with water to reduce the levels of Na and Ci, (b) washing with an aqueous solution of aluminium lactate to reduce the levels of Na and Cl and to increase the levels of soluble aluminium, (c) adding aluminium lactate to the coal without reducing Na and Ci (d) adding sodium aceta to the coal without reducing Na and Cl and (e) adding sodium acetate and aluminium lactate without reducing Na and Cl. Closely controlled combustion experiments utilising a drop-tube furnace temperatures of 1000 °C,1200 °C and 1400 °C have been conducted.
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1993 |
ZHANG DK, WALL TF, 'AN ANALYSIS OF THE IGNITION OF COAL-DUST CLOUDS', COMBUSTION AND FLAME, 92 475-480 (1993)
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1993 |
TORRESORDONEZ RJ, WALL TF, LONGWELL JP, SAROFIM AF, 'SULFUR RETENTION AS CAS(S) DURING COAL COMBUSTION - A MODELING STUDY TO DEFINE MECHANISMS AND POSSIBLE TECHNOLOGIES', FUEL, 72 633-643 (1993)
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1993 |
ZHANG DK, LI T, COTTERILL GF, OCONNOR DJ, WALL TF, 'STM EXAMINATION OF O2 ETCHING ON GRAPHITE SURFACES IN AIR', FUEL, 72 1454-1455 (1993)
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1993 |
WALL TF, BHATTACHARYA SP, ZHANG DK, GUPTA RP, HE X, 'THE PROPERTIES AND THERMAL EFFECTS OF ASH DEPOSITS IN COAL-FIRED FURNACES', PROGRESS IN ENERGY AND COMBUSTION SCIENCE, 19 487-504 (1993)
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1992 |
HILLS PC, ZHANG DK, SAMSON PJ, WALL TF, 'LASER IGNITION OF COMBUSTIBLE GASES BY RADIATIVE HEATING OF SMALL PARTICLES', COMBUSTION AND FLAME, 91 399-412 (1992)
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1992 |
ZHANG DK, HILLS PC, WALL TF, TATE AG, 'THE IGNITION OF COAL PARTICLES AND EXPLOSIONS IN SURROUNDING COMBUSTIBLE GASES DURING HEATING BY LASER IRRADIATION', FUEL, 71 1206-1207 (1992)
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1992 |
ZHANG DK, WALL TF, HARRIS DJ, SMITH IW, CHEN JY, STANMORE BR, 'EXPERIMENTAL STUDIES OF IGNITION BEHAVIOR AND COMBUSTION REACTIVITY OF PULVERIZED FUEL-PARTICLES', FUEL, 71 1239-1246 (1992)
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1992 |
ZHANG DK, WALL TF, TATE AG, 'THE REACTIVITY OF PULVERIZED COAL CHAR PARTICLES - EXPERIMENTS USING IGNITION, BURNOUT AND DTG TECHNIQUES AND PARTLY BURNT CHARS', FUEL, 71 1247-1253 (1992)
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1992 |
Wall TF, 'Mineral matter transformations and ash deposition in pulverised coal combustion', Symposium (International) on Combustion, 24 1119-1126 (1992)
During combustion the inorganic constituents of coal are transformed into products (including vapors, aerosols and residual ash particles) which may transfer to furnace walls and ... [more]
During combustion the inorganic constituents of coal are transformed into products (including vapors, aerosols and residual ash particles) which may transfer to furnace walls and form deposits which restrict heat transfer. Many of the mechanisms of these transformations have now been identified and are detailed by considering the elements, iron and sodium, which have been associated with slagging and fouling respectively. Developments in the scientific analysis of ash deposition, based on these mechanisms, include techniques for coal characterisation, control techniques, the development of engineering deposition parameters and mathematical modelling of the processes. © 1992 Combustion Institute.
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1992 |
Zhang DK, Hills PC, Zheng C, Wall TF, Samson P, 'Fibre optic ignition of combustible gas mixtures by the radiative heating of small particles', Symposium (International) on Combustion, 24 1761-1767 (1992)
Contrary to widely held belief optical fibre cables in hazards are not intrinsically safe. This paper presents the results of both experimental and theoretical investigations into... [more]
Contrary to widely held belief optical fibre cables in hazards are not intrinsically safe. This paper presents the results of both experimental and theoretical investigations into the intrinsic safety of optical fibre in combustible environments. Continuous wave (CW) optical power in the order of 100 mW and pulsed optical power in the order of 10 W (peak) with 100 µs pulse width and 10 Hz repetition rate (average power of 10 mW), delivered by multimode optical fibres, and incident onto dust particles, created explosions in H2/air and CH4/air mixtures. These power levels are generally higher than those used in communication systems but are not atypical of certain sensing systems. A mathematical model was developed to predict the optical power required to ignite a combustible gas by optically heating a small particle and to verify the ignition/explosion mechanisms. The effects of gas concentrations, particle size and particle surface reaction are determined and particle-laser beam interaction are detailed. The model suggests that reactive coal particles can change the gas ignition/explosion behaviour as the coal/oxygen combustion generates thermal energy to increase the particle heating, or consumes oxygen locally to cease the ignition of gases. © 1992 Combustion Institute.
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1992 |
Wall TF, Tate AG, Bailey JG, Jenness LG, Mitchell RE, Hurt RH, 'The temperature, burning rates and char character of pulverised coal particles prepared from maceral concentrates', Symposium (International) on Combustion, 24 1207-1215 (1992)
Maceral concentrates, extracted by selective sampling from the coal face, were burnt as pulverised fuel in order to obtain the temperatures of many hundred individual particles of... [more]
Maceral concentrates, extracted by selective sampling from the coal face, were burnt as pulverised fuel in order to obtain the temperatures of many hundred individual particles of pulverised coal at several combustion times by two-colour pyrometry. The concentrate having a 93.7% vitrinite-rich analysis generates chars of fine walled cenospheres, with openings in the walls, which burn at high temperature, whereas the concentrate with a 89.2% intertinite-rich analysis generates chars of lower porosity and higher density which burn at a lower, and more uniform, temperature. The vitrinite-rich concentrate also burns with an increasing spread in the population of particle temperatures, the inertinite-rich concentrate burns with a decrease in this spread. Due to higher char densities and lower reactivities the burning time of the inertinite-rich concentrate is estimated to be from 2.9 to 3.8 times that of the vitrinite-rich concentrate. Reactivity distributions are estimated from the temperature populations by fixing the activation energy of the chemical rate coefficient and allowing the pre-exponential factor to accommodate the reactivity spread. An increase in the spread of the estimated distributions is evident at high burnoffs. © 1992 Combustion Institute.
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1992 |
Wall TF, Salusinszy AL, Ebeling DB, Drewe GR, Sullivan KM, Beeran P, Smith GB, 'Energy options for the 21st century an Australian perspective', Energy Sources, 14 253-263 (1992)
The present and future demand and use of energy in Australia is reviewed, with consideration of natural gas, liquid fuels, coal, nuclear energy, synfuels, and renewables. The impa... [more]
The present and future demand and use of energy in Australia is reviewed, with consideration of natural gas, liquid fuels, coal, nuclear energy, synfuels, and renewables. The impact of energy on the economy and concerns related to the environment are expected to promote cleaner and more efficient energy systems. © 1992 Taylor and Francis Group, LLC.
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1991 |
WALL TF, GUPTA RP, GURARAJAN VS, ZHANG DK, 'THE IGNITION OF COAL PARTICLES', FUEL, 70 1011-1016 (1991)
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1991 |
Wall TF, Gururajan VS, Lucas J, Gupta RP, Dong-Ke Z, Smith IW, Young BC, 'The ignition, burning rate and reactivity of petroleum coke', Symposium (International) on Combustion, 23 1177-1184 (1991)
The kinetics of combustion of a size-graded fractions of petroleum coke (VM 0.9% db) of pulverised fuel size is determined by measuring the carbon burning rate in a CSIRO laminar ... [more]
The kinetics of combustion of a size-graded fractions of petroleum coke (VM 0.9% db) of pulverised fuel size is determined by measuring the carbon burning rate in a CSIRO laminar flow reactor and using a critical ignition technique where a pulse of coke falls into a drop-tube furnace. At the temperatures where a visible flash is observed in the ignition technique little combustion is found to occur and the coke reactivities estimated assuming heterogeneous ignition exceed those from the burning rate by factors from 102 to 103 depending on assumptions made regarding the products of combustion and the definition of the critical ignition temperature. Ignition experiments with coke recycled through the furnace and coke doped with volatile materials indicate the temperature where flashing is detected decreases as volatiles are added and increases as volatiles are removed. The common assumption of heterogeneous ignition in such experiments may not be valid even for fuels of such low volatility. © 1991 Combustion Institute.
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1991 |
Lindner ER, Wall TF, 'Sodium ash reactions during combustion of pulverised coal', Symposium (International) on Combustion, 23 1313-1321 (1991)
Reactions of sodium with mineral silicates contribute to the formation of fireside deposits during the combustion of some high sodium coals. A systematic experimental study of the... [more]
Reactions of sodium with mineral silicates contribute to the formation of fireside deposits during the combustion of some high sodium coals. A systematic experimental study of the reactions between sodium with inherent silica and kaolin during pulverised coal combustion was undertaken in order to examine the mechanisms of the reactions. The experiments were conducted in a drop tube furnace with coal samples which had been specially prepared to control the concentrations, the size and the distribution of the inorganic constituents, which included silica, kaolin, sodium chloride, sodium acetate, and gaseous SO2 to simulate organic sulfur. The rate of formation of sodium silicate was found to increase with temperature but the extent of formation was limited by the progressive agglomeration and coalescence of the ash which reduced the surface area available for reaction. The extent of interaction between the sodium and silica/silicates was reduced by the presence of chlorine and sulphur and this effect was greater with kaolin than with quartz. At gas temperatures of 1200-1400°C, sodium was volatilised from the coal before significant reactions occurred with the silica. At 1000°C the sodium was not fully released prior to the commencement of the silicate formation reaction. © 1991 Combustion Institute.
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1990 |
APTE VB, WALL TF, TRUELOVE JS, 'STRESS-DISTRIBUTION IN A PACKED-BED ABOVE RACEWAY CAVITIES FORMED BY AN AIR-JET', AICHE JOURNAL, 36 461-468 (1990)
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1990 |
GUPTA RP, GURURAJAN VS, LUCAS JA, WALL TF, 'IGNITION TEMPERATURE OF PULVERIZED COAL PARTICLES - EXPERIMENTAL-TECHNIQUES AND COAL-RELATED INFLUENCES', COMBUSTION AND FLAME, 79 333-339 (1990)
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1990 |
GURURAJAN VS, WALL TF, GUPTA RP, TRUELOVE JS, 'MECHANISMS FOR THE IGNITION OF PULVERIZED COAL PARTICLES', COMBUSTION AND FLAME, 81 119-132 (1990)
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1990 |
BAILEY JG, TATE A, DIESSEL CFK, WALL TF, 'A CHAR MORPHOLOGY SYSTEM WITH APPLICATIONS TO COAL COMBUSTION', FUEL, 69 225-239 (1990)
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1989 |
Wall T, 'Energy options for the next century', CEA : chemical engineering in Australia, 14 14-18 (1989)
The author discusses those issues which are seen as being of long term importance. This is followed by Australian energy use in the areas of natural gas, liquid fuels, coal, nucle... [more]
The author discusses those issues which are seen as being of long term importance. This is followed by Australian energy use in the areas of natural gas, liquid fuels, coal, nuclear fission energy and synfuels. Expected trends in demand are outlined. Energy and the economy are examined along with energy and environment.
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1988 |
GURURAJAN VS, WALL TF, TRUELOVE JS, 'THE COMBUSTION OF EVOLVED VOLATILE MATTER IN THE VICINITY OF A COAL PARTICLE - AN EVALUATION OF THE DIFFUSION LIMITED MODEL', COMBUSTION AND FLAME, 72 1-12 (1988)
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1988 |
WALL TF, PHONGANANT D, GURURAJAN VS, WIBBERLEY LJ, TATE A, LUCAS J, 'INDICATORS OF IGNITION FOR CLOUDS OF PULVERIZED COAL', COMBUSTION AND FLAME, 72 111-118 (1988)
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1988 |
Jamaluddin AS, Wall TF, Truelove JS, 'Combustion of pulverized coal as a tuyère-injectant to the blast furnace', Symposium (International) on Combustion, 21 575-584 (1988)
A theoretical-experimental study of the combustion of pulverized coal in the blowpipe and raceway of the blast furnace was undertaken. The objective of the study was to develop a ... [more]
A theoretical-experimental study of the combustion of pulverized coal in the blowpipe and raceway of the blast furnace was undertaken. The objective of the study was to develop a mathematical model of combustion, and to evaluate it against experimental data. Both experimental and theoretical work involved three levels of complexity: (1) Laboratory-scale studies on coal devolatilization; (2) Pilot-scale combustion studies in a physical blowpipe-model; and (3) Combustion studies in a full-scale blast furnace. The predictions of the theoretical models compared favourably with the experimental data. Coal grind and devolatilization characteristics are shown to have a substantial effect on coal burnoff. Dispersion of the injected coal within the main blast is found to have a significant effect on coal burnoff. Gas recirculation and coke combustion within the raceway are found to influence the combustion of the injected coal. © 1988 Combustion Institute.
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1988 |
APTE VB, WALL TF, TRUELOVE JS, 'GAS-FLOWS IN RACEWAYS FORMED BY HIGH-VELOCITY JETS IN A TWO-DIMENSIONAL PACKED-BED', CHEMICAL ENGINEERING RESEARCH & DESIGN, 66 357-362 (1988)
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1987 |
Mahmud T, Truelove JS, Wall TF, 'Flow characteristics of swirling coaxial jets from divergent nozzles.', TRANS. ASME J. FLUIDS ENGNG., 109 (1987)
The aerodynamic characteristics of free, swirling, coaxial jets issuing from an air model of a typical burner for pulverized bituminous coal were studied. Detailed measurements of... [more]
The aerodynamic characteristics of free, swirling, coaxial jets issuing from an air model of a typical burner for pulverized bituminous coal were studied. Detailed measurements of mean velocity and static pressure were obtained in the region near the nozzle exit. The boundary of the reverse flow zone as mapped and the recirculated mass flowrate measured in order to quantify the effects of velocity ratio and swirl in the primary and secondary jets. The influence of burner geometry (divergent nozzle length and centre line blockage) were studied. The type of flow pattern is found to depend upon the level of swirl in the primary and secondary jets. The recirculated mass flowrate is predominantly influenced by secondary swirl. The measurements were compared with predictions obtained by numerical solution of the governing conservation equations in orthogonal curvilinear coordinates. The general features of the flows are adequately predicted although discrepancies in detail seem to indicate deficiencies in the turbulence model. (A)
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1987 |
JAMALUDDIN AS, WALL TF, TRUELOVE JS, 'MODELING OF HIGH-INTENSITY COMBUSTION OF PULVERIZED COAL IN A TUBULAR COMBUSTOR', COMBUSTION SCIENCE AND TECHNOLOGY, 55 89-113 (1987)
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1987 |
MAHMUD T, TRUELOVE JS, WALL TF, 'FLOW CHARACTERISTICS OF SWIRLING COAXIAL JETS FROM DIVERGENT NOZZLES', JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME, 109 275-282 (1987)
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1986 |
JAMALUDDIN AS, TRUELOVE JS, WALL TF, 'DEVOLATILIZATION OF BITUMINOUS COALS AT MEDIUM TO HIGH HEATING RATES', COMBUSTION AND FLAME, 63 329-337 (1986)
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1986 |
WALL TF, PHELAN WJ, BORTZ S, 'COAL BURNOUT IN THE IFRF NO 1 FURNACE', COMBUSTION AND FLAME, 66 137-150 (1986)
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1986 |
WALL TF, GURURAJAN VS, 'COMBUSTION KINETICS AND THE HETEROGENEOUS IGNITION OF PULVERIZED COAL', COMBUSTION AND FLAME, 66 151-157 (1986)
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1986 |
WIBBERLEY LJ, WALL TF, 'AN INVESTIGATION OF FACTORS AFFECTING THE PHYSICAL CHARACTERISTICS OF FLY-ASH FORMED IN A LABORATORY SCALE COMBUSTOR', COMBUSTION SCIENCE AND TECHNOLOGY, 48 177-190 (1986)
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1986 |
JAMALUDDIN AS, WALL TF, TRUELOVE JS, 'MATHEMATICAL-MODELING OF COMBUSTION IN BLAST-FURNACE RACEWAYS, INCLUDING INJECTION OF PULVERIZED COAL', IRONMAKING & STEELMAKING, 13 91-99 (1986)
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1985 |
GUPTA RP, WALL TF, 'THE OPTICAL-PROPERTIES OF FLY-ASH IN COAL FIRED FURNACES', COMBUSTION AND FLAME, 61 145-151 (1985)
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1985 |
PHONGANANT D, WIBBERLEY LJ, WALL TF, 'NITROGEN-OXIDE FORMATION FROM AUSTRALIAN COALS', COMBUSTION AND FLAME, 62 21-30 (1985)
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1985 |
JAMALUDDIN AS, TRUELOVE JS, WALL TF, 'MODELING OF COAL DEVOLATILIZATION AND ITS EFFECT ON COMBUSTION CALCULATIONS', COMBUSTION AND FLAME, 62 85-89 (1985)
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1984 |
WALL TF, BECKER HB, 'TOTAL ABSORPTIVITIES AND EMISSIVITIES OF PARTICULATE COAL ASH FROM SPECTRAL BAND EMISSIVITY MEASUREMENTS', JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, 106 771-776 (1984)
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1983 |
JAMALUDDIN AS, TRUELOVE JS, WALL TF, 'INTRINSIC REACTIVITY OF CARBONS TO OXYGEN', FUEL, 62 484-486 (1983)
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1983 |
GUPTA RP, WALL TF, TRUELOVE JS, 'RADIATIVE SCATTER BY FLY-ASH IN PULVERIZED-COAL-FIRED FURNACES - APPLICATION OF THE MONTE-CARLO METHOD TO ANISOTROPIC SCATTER', INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, 26 1649-1660 (1983)
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1983 |
DIXON TF, TRUELOVE JS, WALL TF, 'AERODYNAMIC STUDIES ON SWIRLED CO-AXIAL JETS FROM NOZZLES WITH DIVERGENT QUARLS', JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME, 105 197-203 (1983)
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1982 |
WIBBERLEY LJ, WALL TF, 'ALKALI-ASH REACTIONS AND DEPOSIT FORMATION IN PULVERIZED-COAL-FIRED BOILERS - THE THERMODYNAMIC ASPECTS INVOLVING SILICA, SODIUM, SULFUR AND CHLORINE', FUEL, 61 87-92 (1982)
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1982 |
WIBBERLEY LJ, WALL TF, 'ALKALI-ASH REACTIONS AND DEPOSIT FORMATION IN PULVERIZED-COAL-FIRED BOILERS - EXPERIMENTAL ASPECTS OF SODIUM-SILICATE FORMATION AND THE FORMATION OF DEPOSITS', FUEL, 61 93-100 (1982)
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1982 |
WALL TF, SUBRAMANIAN V, HOWLEY P, 'AN EXPERIMENTAL-STUDY OF THE GEOMETRY, MIXING AND ENTRAINMENT OF PARTICLE-LADEN JETS UP TO 10 DIAMETERS FROM THE NOZZLE', TRANSACTIONS OF THE INSTITUTION OF CHEMICAL ENGINEERS, 60 231-239 (1982)
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1982 |
Wall TF, Duong HT, Stewart IMC, Truelove JS, 'Radiative heat transfer in furnaces: Flame and furnace models of the IFRF M1- and M2-trials', Symposium (International) on Combustion, 19 537-547 (1982)
Furnace heat transfer models-using the zone and flux methods-have previously beenevaluated against measurements from the M1-furnace trials of the International Flame Research Foun... [more]
Furnace heat transfer models-using the zone and flux methods-have previously beenevaluated against measurements from the M1-furnace trials of the International Flame Research Foundation. The M1 furnace configuration is shown to be insensitive to flame and combustion changes and is, therefore, a poor test of a model. A simple zoned model-using the Monte Carlo technique-is then evaluated on the later, more sensitive, M2-trials when the proportion of the furnace walls as a heat sink was increased. The model allows for variation in flame shape and the concentration of emitters between zones. A simple zoning for the end-fired furnace comprising a single flame zone, a recirculation region and two zones between the flame and the furnace exist is shown to be quite adequate for predictions of furnace heat transfer. A more detailed description of the flame and furnace may not be warranted even when the flow and combustion pattern is known in detail. © 1982 Combustion Institute.
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1982 |
Truelove JS, Wall TF, Dixon TF, Stewart IMC, 'Flow, mixing and combustion within the quarl of a Swirled, pulverised-coal burner', Symposium (International) on Combustion, 19 1181-1187 (1982)
Measurements are presented of the flow pattern and mixing within the quarl of a 1/9th-scaleair model of a brown coal burner. For flow conditions within the range used in operating... [more]
Measurements are presented of the flow pattern and mixing within the quarl of a 1/9th-scaleair model of a brown coal burner. For flow conditions within the range used in operating burners, two flow types were observed: one, previously reported, where the primary (coal-laden) flow is deflected gradually around a central, swirl-induced, reverse-flow zone; the other, where the primary flow partially penetrates the reverse-flow zone before being deflected rapidly in the radial direction. The combustion behaviour of the coal in each type of flow is predicted by a computationalmodel, and the results compared with limited measurements on an industrial burner. The second type of flow is shown to mix the coal-laden primary flow with the internal reverse flow before mixing with the secondary air flow, resulting in a higher evolution of volatiles and the ignition of a greater proportion of the char mass. The temperature field within the quarl is shown to be dominated by the temperature of the reverse flow. © 1982 Combustion Institute.
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1981 |
WALL TF, LOWE A, WIBBERLEY LJ, MAIVIET T, GUPTA RP, 'FLY-ASH CHARACTERISTICS AND RADIATIVE HEAT-TRANSFER IN PULVERIZED-COAL-FIRED FURNACES', COMBUSTION SCIENCE AND TECHNOLOGY, 26 107-121 (1981)
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1981 |
GUPTA RP, WALL TF, 'THE COMPLEX REFRACTIVE-INDEX OF PARTICLES', JOURNAL OF PHYSICS D-APPLIED PHYSICS, 14 L95-L98 (1981)
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1981 |
BECKER HB, WALL TF, 'EFFECT OF SPECULAR REFLECTION OF HEMISPHERICAL SURFACE PYROMETER ON EMISSIVITY MEASUREMENT', JOURNAL OF PHYSICS E-SCIENTIFIC INSTRUMENTS, 14 998-1001 (1981)
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1980 |
JUNIPER LA, WALL TF, 'COMBUSTION OF PARTICLES IN A LARGE PULVERIZED BROWN COAL FLAME', COMBUSTION AND FLAME, 39 69-81 (1980)
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1980 |
Endersbee LA, Baxter P, Butters JW, Corbett AH, Dembecki JA, Durie RA, et al., 'An energy policy for Australia. Extracts from the summary report and recommendations of the Task Force on Energy of The Institution of Engineers, Australia', Energy, 5 295-323 (1980)
Over the next few years, Australia must modify its dependence on natural oil and place greater reliance on other fossil fuels and renewable energy sources. The management of this ... [more]
Over the next few years, Australia must modify its dependence on natural oil and place greater reliance on other fossil fuels and renewable energy sources. The management of this transition is a major task, and can only be successfully achieved through a co-ordinated programme of action by Commonwealth and State Governments, supported by widespread public understanding of the issues involved. The recommendations in this report have arisen from the deliberations of the Task Force on Energy, which commenced work in 1975. The Task Force and its associated twelve working parties included many of the leading energy experts in Australia, in engineering, science and economics. They are associated with State Governments and energy instrumentalities, Commonwealth agencies, private enterprise, consulting engineering, universities and research bodies, but have co-operated in the work of the Task Force in their personal capacities. Overall, at least one hundred key specialists were associated with the working party studies. There was wide-ranging national co-operation in these studies, and information on critical energy issues throughout Australia was freely exchanged. © 1980.
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1980 |
WALL TF, NGUYEN H, SUBRAMANIAN V, MAIVIET T, HOWLEY P, 'DIRECT MEASUREMENTS OF THE ENTRAINMENT BY SINGLE AND DOUBLE CONCENTRIC JETS IN THE REGIONS OF TRANSITION AND FLOW ESTABLISHMENT', TRANSACTIONS OF THE INSTITUTION OF CHEMICAL ENGINEERS, 58 237-241 (1980)
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1979 |
Lowe A, Stewart IMC, Wall TF, 'The measurement and interpretation of radiation from fly ash particles in large pulverized coal flames', Symposium (International) on Combustion, 17 105-114 (1979)
Narrow wave-band measurements have been used to determine the absorption coefficient of combustion chamber gases in large utility boilers with an accuracy of about ±25%. Effective... [more]
Narrow wave-band measurements have been used to determine the absorption coefficient of combustion chamber gases in large utility boilers with an accuracy of about ±25%. Effective absorption efficiencies and refractive indices for, the fly ash have been deduced where dust burden details could be measured. Modifications to instrument design would improve the accuracy. The absorption characteristics were shown to be influenced by the chemical composition of the ash. For a brown and a sub-bituminous coal of high alkali ash the measurements indicated a very high specific surface in the furnace, incompatible with sizing of collected fly ash samples, and a very high wavelength dependence of absorption. Small molten particles in the furnace gases could account for the high apparent surface area and the wavelength dependence. Results for two bituminous coals with high ash fusion temperatures indicate that an absorption coefficient over(K, -)a of 0.4 to 0.5 would be adequate for eingineering purposes. However this value appears to be strongly influenced by chemical composition of ash; the cloud surface area may be more dependent on inherent ash and combustion characteristics than on the total ash or the coal grind. © 1979 Combustion Institute.
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1979 |
WALL TF, LOWE A, WIBBERLEY LJ, STEWART IM, 'MINERAL MATTER IN COAL AND THE THERMAL PERFORMANCE OF LARGE BOILERS', PROGRESS IN ENERGY AND COMBUSTION SCIENCE, 5 1-29 (1979)
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1979 |
Wall TF, Nguyen HH, Subramanian V, Mai-Viet T, 'ENTRAINMENT OF SINGLE, DOUBLE CONCENTRIC AND PARTICLE LADEN JETS CLOSE TO THE NOZZLE.', National Conference Publication - Institution of Engineers, Australia, 84-88 (1979)
The entrainment of an axisymmetric air jet, a double concentric jet and jets laden with fine solids are estimated up to an axial distance of 15 nozzle diameters by a direct measur... [more]
The entrainment of an axisymmetric air jet, a double concentric jet and jets laden with fine solids are estimated up to an axial distance of 15 nozzle diameters by a direct measurement based on the experimental method previously used by Ricou and Spalding for the region further distant from the nozzle. The results for axisymmetric are best correlated by the equation which is presented. Beyond 15 diameters the data blends into previous direct measurement by Field, but it falls substantially below many previous measurements which overestimate entrainment by up to 25%. For the double concentric jet the entrainment measurements are best normalized with respect to the secondary flow.
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1979 |
Wall TF, Nguyen HH, Subramanian V, Mai-Viet T, 'The entrainment of single, double concentric and particle laden jets close to the nozzle.', IN: CHEMECA 79, NAT. CONF. ON CHEM. ENGNG. 1979, ON EXPANDING HORIZONS IN CHEMICAL ENGINEERING, (NEWCASTLE, AUSTRALIA: AUG.22, 84-88 (1979)
The entrainment of an axi-symmetric air jet, a double concentric jet and jets laden with fine solids are estimated up to an axial distance of 15 nozzle diameters by a direct measu... [more]
The entrainment of an axi-symmetric air jet, a double concentric jet and jets laden with fine solids are estimated up to an axial distance of 15 nozzle diameters by a direct measurement based on the experimental method previously used by Ricou and Spalding for the region further distant from the nozzle. (from authors abstract)
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1978 |
Wall TF, Sergeant GD, 'EDUCATIONAL PROGRAMMES FOR THE EFFICIENT USE OF ENERGY IN AUSTRALIAN INDUSTRY.', ASTM Special Technical Publication, 316-321 (1978)
A review is made of the quantity and quality of formal courses at all levels of education in Australia in terms of the content which provides the background for an understanding a... [more]
A review is made of the quantity and quality of formal courses at all levels of education in Australia in terms of the content which provides the background for an understanding and assessment of energy usage necessary for an effective program of energy conservation. At all levels - secondary, trade and university - this content was found to be lacking. In addition, courses in energy management offered by professional institutes, fuel suppliers and in-house courses in industry are presented. The co-ordination of this expanding program to reduce duplication is recommended.
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1977 |
LOWE A, WALL TF, STEWART IM, 'COMBUSTION KINETICS IN MODELING OF LARGE, PULVERIZED FUEL FURNACES - NUMERICAL EXPERIMENT IN SENSITIVITY', AICHE JOURNAL, 23 440-448 (1977)
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1977 |
Stewart IMC, Wall TF, 'Reaction rate analysis of borehole 'in-situ' gasification systems', Symposium (International) on Combustion, 16 525-533 (1977)
Performance is reported for quasi-steady state computational models of two zones of borehole type in-situ gasification systems. The plug-flow reduction zone is a close replica of ... [more]
Performance is reported for quasi-steady state computational models of two zones of borehole type in-situ gasification systems. The plug-flow reduction zone is a close replica of real systems; the well-stirred reactor models some special systems and may be indicative of a wide range of ignition zone conditions. For both models it is postulated that seam moisture evaporation and coal devolatilization occur at some distance (inversely proportional to the advance rate) behind a reacting face of coke and that reaction of these products with coke occurs behind the face. This model produces an apparent reactivity for the system more strongly dependent on seam moisture and volatile content than on the chemical reactivity of the coke. Computations predict that gasification efficiency and combustion stability are sensitive to an optimal combination of seam moisture and of blast moisture. These findings and the predicted gas analyses and efficiencies are generally in line with what published field information is available. The advantageous effect of high moisture content in the gas is to increase reaction rate (by increasing the concentration of a major reactant); this is balanced by the temperature drop due to added heat capacity. The overall effect is so dramatic as to warrant this type of analysis before completing design for field experiments. Laboratory testing on large samples of seam coal is advisable to test the model for detail and obtain better rate coefficients. It is predicted that high ratings and high gasification efficiencies are possible for oxygensteam gasification either in plug-flow or W.S.R. systems, particularly if preheat can be achieved. © 1977 Combustion Institute.
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1977 |
Wall TF, Boon KK, 'PREDICTION OF RADIATIVE TRANSFER IN UTILITY FURNACES BY COMPUTER SIMULATION. 453-460 (1977)
The Hottel-Cohen technique is used to simulate the performance of two utility boilers fired with pulverized coal. Unique measurements of the spectral radiation of fly ash show tha... [more]
The Hottel-Cohen technique is used to simulate the performance of two utility boilers fired with pulverized coal. Unique measurements of the spectral radiation of fly ash show that it is not a gray emitter, the implication being that considerations must be given to the nongray nature of ash and the triatomic gases for a realistic representation of radiative interchange between zones. An initial approach to this consideration is detailed whereby the radiative interchange between each zone-pair-combination is approximated by a black-gray-clear model for the emissivity-distance characteristics of the furnace gases.
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1976 |
WALL TF, RUKTANONCHAI P, 'RECOMBINATION OF DISSOCIATED GASES IN BOUNDARY-LAYERS SURROUNDING FINE PARTICLES', TRANSACTIONS OF THE INSTITUTION OF CHEMICAL ENGINEERS, 54 61-64 (1976) |
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1976 |
McC Stewart I, Wall TF, 'REACTION RATE ANALYSIS OF BOREHOLE 'IN-SITU' GASIFICATION SYSTEMS. 525-533 (1976)
Performance is reported for quasi-steady state computational models of two zones of borehole type in-situ gasification systems. The plug-flow reduction zone is a close replica of ... [more]
Performance is reported for quasi-steady state computational models of two zones of borehole type in-situ gasification systems. The plug-flow reduction zone is a close replica of real systems; the well-stirred reactor (W. S. R. ) models have special systems and may be indicative of a wide range of ignition zone conditions. Computations predict that gasification effciency and combustion stability are sensitive to an optimal combination of seam moisture and of blast moisture. It is predicted that high ratings and high gasification efficiencies are possible for oxygen-steam gasification either in plug-flow or W. S. R. systems, particularly if preheat can be achieved.
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1975 |
Lowe A, Wall TF, Stewart IMC, 'A zoned heat transfer model of a large tangentially fired pulverized coal boiler', Symposium (International) on Combustion, 15 1261-1270 (1975)
A mechanistic model of a tangentially-fired pulverised-fuel furnace of 900 MW thermal input is described, in which a zoned method of computation predicts the temperature distribut... [more]
A mechanistic model of a tangentially-fired pulverised-fuel furnace of 900 MW thermal input is described, in which a zoned method of computation predicts the temperature distribution within the chamber and the heat absorbed by the water-tube walls. The cylindrical model, comprising 45 gas and 21 surface zones, approximates the furnace, which is rectangular in cross section. The flow pattern within the chamber is assumed but the treatment of coal combustion and the complexities of radiative inter-change are rigorous within the liminations of the method. A series of simulations to demonstrate the effect of variation in gas flow pattern, boiler load and ash content in the coal is presented. These show that variation in the specific surface of the ash has a dominating influence, whereas the effect of the flow pattern is smally by comparison. Measurements taken on the actual furnace provide a check on the validity of the model. Comparisons are generally good although temperature predicted close to the furnace walls at burner level are consistently low. Investigations to improve the comparisons, and the method in general, are recommended. © 1975 Combustion Institute.
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1975 |
Lowe A, Wall TF, Stewart IMC, 'ZONED HEAT TRANSFER MODEL OF A LARGE TANGENTIALLY FIRED PULVERIZED COAL BOILER. 1261-1270 (1975)
A mechanistic model of a tangentially-fired pulverized-fuel furnace of 900 Mw thermal input is described, in which a zoned method of computation predicts the temperature distribut... [more]
A mechanistic model of a tangentially-fired pulverized-fuel furnace of 900 Mw thermal input is described, in which a zoned method of computation predicts the temperature distribution within the chamber and the heat absorbed by the water-tube walls. A series of simulations to demonstrate the effect of variation in gas flow pattern, boiler load and ash content in the coal is presented. These show that variation in the specific surface of the ash has a dominating influence, whereas the effect of the flow pattern is small by comparison. Measurements taken on the actual furnace provide a check on the validity of the model.
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1974 |
Barvarz RG, Tait RJ, Wall TF, 'STAGNATION-POINT HEAT TRANSFER FROM ELECTRICALLY AUGMENTED FLAMES TO METAL SURFACES. 165-173 (1974)
A large increase in the rate of heat transfer from a combustion flame can be obtained by augmenting it with an electrical discharge. Electrically augmented flames are, therefore, ... [more]
A large increase in the rate of heat transfer from a combustion flame can be obtained by augmenting it with an electrical discharge. Electrically augmented flames are, therefore, very attractive for high-temperature metallurgical processing; their application to flame-hardening has already been studied and the present work is directed at metal melting. Stagnation-point heat fluxes have been obtained when a stoichiometric methane-air flame was directed on to a steel slab, which contained a heat flux meter. Augmenting the flame with a quantity of electrical energy equal to the chemical energy in the flame was found to increase the stagnation-point heat flux by a factor of 8. Heat fluxes have also been predicted from existing heat-transfer correlations for partially dissociated gases. The experimental values were found to be 4-6 times greater than the predictions, because of non-uniform distribution of the electrical energy in the flame. As the surface temperature approached the melting point of the steel, the heat flux decreased to a greater extent than could be predicted from the enthalpy driving force.
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1974 |
Tait RJ, Wall TF, 'REDUCTION OF HEMATITE PARTICLES INJECTED INTO AN ELECTRICALLY AUGMENTED FLAME. 39-50 (1974)
A model has been developed to describe the reduction of an oxide particle in an electrically augmented flame. The model shows that the residence time required for complete reducti... [more]
A model has been developed to describe the reduction of an oxide particle in an electrically augmented flame. The model shows that the residence time required for complete reduction is very short, e. g. , a 50- mu m hema particle can be reduced to metallic iron in 0. 05 s by use of a boost ratio of unity. The presence of dissociated hydrogen is responsible for these rapid reaction rates, the rates being particularly fast at high particle temperatures, when a large proportion of the hydrogen atoms react directly with the particle, instead of recombining. Hematite particles - 200 mesh in size were injected into the nozzle of an electrically augmented burner to test the validity of the model. At boost ratios of unity or more a large proportion of the particles were found to be spheroidized and partially reduced after quenching. The use of a more fuel-rich flame, together with arc rotation, is proposed to obtain a uniformly spheroidized and completely reduced product.
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1973 |
Wall TF, Stewart IMC, 'The measurement and prediction of solids- andsoot-absorption coefficients in the flame region of an industrial P.F. chamber', Symposium (International) on Combustion, 14 689-697 (1973)
To increase our knowledge of the role played by particulate matter in radiative transfer inindustrial furnaces, solids-absorption coefficients in the burner region of a tangential... [more]
To increase our knowledge of the role played by particulate matter in radiative transfer inindustrial furnaces, solids-absorption coefficients in the burner region of a tangentially corner-fired pulverized brown-coal boiler are estimated and predicted by various methods. The total solids spectral absorption coefficient is given by ktsol=klsol+A.Csoot/¿, where klsol is due to large-solids (coal, char, ash) and the soot contribution depends on its concentration and the constant A. Radiation pyrometer data, at 0.65 and 0.90 µm, together with suction-temperature data, allows solution for the constants in this equation. A monochromatic intensity calculation along a pyrometer beam to estimate spectral-absorption coefficients is developed and the results of this calculation are used to obtain klsol and Csoot. These values indicate that soot contributes equally with large solids to the total solids emission, and dominates the visible emission. It is shown that large-solids-absorption coefficients can be estimated by a burn-out calculation,and that these values are in reasonable agreement with those obtained independently by radiation measurements. Values obtained for soot-absorption coefficients by radiation measurements are only about one-third as high as those estimated by an empirical equation quoted by Ledinegg. The availability of absorption-coefficient data and estimation methods such as these can contribute significantly to progress in the prediction of radiation from p.f. flames in industrial chambers by the well-known zone technique. © 1973 Combustion Institute.
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1973 |
Stewart IMC, Wall TF, 'TEMPERATURE AND HEAT-TRANSFER IN PULVERIZED COAL FURNACES. 9-16 (1973)
The paper discusses the computation of local radiant fluxes to heating surfaces from a combustion chamber and the relative contribution to the radiant flux from burning char parti... [more]
The paper discusses the computation of local radiant fluxes to heating surfaces from a combustion chamber and the relative contribution to the radiant flux from burning char particles, ash, soot and triatomic gases. It was shown that absorption coefficients for soot and unburned carbon are of about the same value for tangentially fired boilers and can be computed from narrow wave band measurements.
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