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02388 Reduction of toxic trace element concentrations by physically cleaning three finely-ground coals
01
Solid fuels (preparation)
Improving the selectivity of emulsified flotation agent for coal
99102370
Sun, D. et al. Taiyuan Ligong Daxue Xuebno, 1998, 29, (5). 507-510. (In Chinese) A study of a coal flotation agent consisting of kerosene, emulsified by RMl and other anion emulsifiers. Not only did the emulsified agent keep its flotation capacity but it also improved separation selectivity in coal deashing.
The mechanisms of trace element removal during coal cleaning
99102379
Akers, D. J. and Raleigh, C. E., Jr. Coal Prep. (Gordon & Breach), 1998, 19, (3-4). 257-269. As most of the trace elements in coal considered hazardous air pollutant precursors are entirely or primarily associated with mineral matter they are potentially removable using physical coal cleaning processes. Normally, the concentration of trace elements in a coal is reduced when the coal is cleaned to reduce its ash and sulfur content. Through understanding the mechanisms of trace element removal during coal cleaning additional reduction in trace element concentration can be attained. In this paper, the factors that affect trace element reduction are found to be the degree of liberation of trace element-bearing mineral matter, the relative intensity of cleaning, the mode of occurrence of the trace element and the method of cleaning.
Method for reducing water contents in solid materials and/or sludges and apparatus for control and adjustment of filter press 99102380
Bielfeldt, F. B. and Eckhart, K. Jpn. Kokai Tokkyo Koho [98 263,319], (Cl. BOlD25112). 6 Ott 1998, Appl. 97/72,134, 13 pp. (In Japanese) A method for decreasing water content in solid materials, brown coal and/or sludges, is described. It is characterized in generated from the filter press is continuously expanded by an expansion chamber. It is then passed into a steam controlling the expansion speed.
JP 10 263,319 25 Mar 1997, especially raw that the steam passing it into condenser by
99/02391 A novel Sphingomonas capable of selectively desuifurizing dlbenzothiophene for use in biodesulfuriration Darzins, A. and Mrachko, G. T. PCT Int. Appl. WO 98 45,446, (Cl. C12N15/52), 15 Ott 1998, US Appl. 851,089, 5 May 1997, 127 pp. Sphingomonas specific strain AD109, a novel microorganism, is capable of selectively desulfurizing dibenzothiophene. This paper reviews its use in biodesulfurization of fossil fuels, especially coal. The genes for the enzymes involved in the desulfurization of dibenzothiophene were cloned and characterized. The cloned genes for the enzymes can be expressed in a suitable host to enable the costs of coal desulfurization to be lowered. By screening for the ability to use 2-(2-hydroxyphenyl)benzenesulfinate (HPBS) as the sole sulfur source the microorganism was isolated from oil-contaminated soil. The enzyme, responsible for desulfination of HPBS, was purified and characterized by standard methods. The cloning was carried out by screening a Sphingomonas Not1 expression libraty in Escherichia coli for the ability to clear dibenzothiophene 5,5-dioxide plates followed by subcloning to identify the desulfinase gene. 99102382 Optimization flotation centrifuge
of the aeration reactor for a weir
Heidenreich, C. er al. World Congr. Part. Technol. 3, [computer optical disk], 1998, 3134-3144. A new weir flotation centrifuge used for processing anthracite coal and graphite has been developed and is the subject of this study. It applies the counterflow centrifugal separation principle. Aeration and primary mineralization take place outside the separation zone using an aeration reactor with a PTFE frit. Secondary mineralization supported by turbulence is carried out in the separation zone of the centrifuge. This study was aimed at optimizing the process steps taking place in the aeration reactor, especially the investigation of the influence of the porosity and length of the aeration frit and the volume flow ratio of air to suspension. Overall the advantage of the weir flotation centrifuge in comparison to the stationary flotation column and the standard laboratory flotation cell is demonstrated by the results obtained, especially for fine particles.
Preparation of novel pitches by tar air-blowing 99102383 Prada, P. er al. Carbon, 1999, 37, (l), 97-106. High carbon yield coal-tar pitches are prepared by tar air-blowing under pressure (0.5 MPa). The influence of the temperature (275-325”C), reaction time (O-20 h) and air flow (60-120 I h-‘) on pitch composition and properties were monitored by elemental analysis, solubility measurements and Fourier transform infrared spectroscopy. The development of mesophase was monitored in the resultant pitches by optical microscopy of their pyrolysis products obtained at 450°C. Results show that the airblowing of tar, performed under mild conditions, promotes the condensation of molecular components producing cross-linked oligomers, so increasing the yield of the process. The extent of polymerization increased with severity of treatment and resulted in an increase of pitch carbon yield. Moreover, the different properties of prepared pitches offer the possibility to obtain cokes with a wide range of optical textures.
252
Fuel and Energy Abstracts
July 1999
99102384 Process for desulfurization of solid fossil fuels Andres Gimeno, J. M. and Ferrando Navarro, A. C. Span. ES 2.107.383, (Cl. ClOL9/00), 16 Nov 1997, Appl. 9,501,859, 26 Sep 1995, 5 pp. (In Spanish) This desulfurization method comprises mixing the fossil fuel with a desulfurization reagent which contains 57% HI, up to 10% I, 0.2-50% H and an inert gas. This takes place under oxidizing or reducing conditions for 5-15 min, in a closed reactor at l-60 atmospheric pressure, using microwave heating to 25-4Oo”C. Included in the process is an absorption tower to strip and retain the HzS formed during the reaction.
Processes for the sorption of gaseous components at high temperatures (>9OCrC)
99102305
Hubner, K. High Temp. Gas Clean., [Pap. Int. Symp. Exhib. Gas Clean. High Temp./ 3, 1996, 352-363. Edited by Schmidt, E., Institut fur Mechanische Verfahrenstechnik und Mechanik der Universitaet Karlsruhe, Karlsruhe, Germany. Hot gas clean-up is increasingly important as far as the development of novel coal conversion processes using combined gas and steam cycles is concerned. This is not only relevant to the removal of particles, but also to the separation of gaseous pollutants at high temperatures and pressures. The dry removal of acidic gas components (for example SOz. HCI and HF) using calcium compounds is, however, limited by thermodynamic equilibrium. The composition of flue gases from coal conversion means that removal of the hydrogen halides is not viable at temperatures above 800°C. Thermodynamics could be used to achieve the separation of SOz by lime compounds at temperatures up to over 1200°C. However, this reaction is hindered kinetically as a result of sintering effects at temperatures above 900°C. At extreme temperatures, there are no suitable solid agents for the removal of the mentioned pollutants. Theoretically the problems of unsatisfactory thermodynamic equilibrium and kinetic hindering can be overcome by using a mixture of molten salts or oxides. These substances have to fulfil a number of pre-conditions in order for the sorption process to operate successfully, which are detailed. Laboratory and semi-technical scale experiments have achieved separation efficiencies of more than 90% so far. The gas separation process can be combined with corresponding processes to make the removal of particles possible. 99102386
Quality control for roll sleeve of coal pulverizer produced by centrifugal compound casting
Ning, Z. et al. Zhuzao, 1998, (4), 36-38. (In Chinese) This paper examines the roll sleeve of coal pulverizer produced by centrifugal compound casting. Metallurgical and technical factors influencing the quality of double-metal layer and crack formation of the roll sleeve are discussed. The key to quality control of the roll sleeve is suggested to be the control of the metallurgical quality of the double-metal layer and casting stress crack formation prevention.
Rapid devolatilisation of Yallourn brown coal at high pressures and temperatures
99102387
Yeasmin, H. et al. Fuel, 78, (1). 11-24. A pressurized drop-tube furnace was used to study the devolatilization behaviour of Yallourn brown coal. Coal particles of 37-53 /Irn size were devolatilized at pressures of 100, 500 and 1000 kPa. The experiments were carried out at temperatures of 873, 1073 and 1273 K. Residence times were varied from 0.02 to 3 s. Weight loss was calculated based on ash as a tracer. The maximum weight loss due to devolatilization is temperature and pressure dependent. At a particular residence time and pressure, the weight loss increases with an increase in devolatilization temperature. Increasing the pressure not only increases the residence time required to achieve a given level of weight loss, but also reduces the total weight loss attainable at a particular temperature. Weight loss due to devolitilization was fitted by a two-stage first-order kinetic expression. The calculated kinetic parameters are considerably lower than the reported parameters for lignites and bituminous coals. It appears that initial devolatilization of Yallourn brown coal is mainly dominated by very low activation energy. Variation of activation energy with the level of devolatilization was observed. This variation could be partially due to the presence of active sites in the char with different characteristic reactivities.
Reduction of toxic trace element concentrations by physically cleaning three finely-ground coals
99102388
Smit, F. J. er al. Coal Prep. (Gordon & Breach), 1998, 19, (3-4), 231-241. This paper describes a study of an advanced physical coal cleaning process comprising column flotation and selective agglomeration (with recycle heptane bridging liquid) in a 2-t/h process development unit (PDU). The residual concentrations of 12 toxic trace element impurities, including mercury and selenium, in ground Taggart, Indiana VII and Hiawatha coals were determined after they had undergone this process. For each of the trace elements, the reduction in concentration from the amount in the runof-mine (ROM) parent coals and the amount in the washed test coals was also determined, on a heating value basis.
Solid fuels (preparation)
Improving the selectivity of emulsified flotation agent for coal
99102370
Sun, D. et al. Taiyuan Ligong Daxue Xuebno, 1998, 29, (5). 507-510. (In Chinese) A study of a coal flotation agent consisting of kerosene, emulsified by RMl and other anion emulsifiers. Not only did the emulsified agent keep its flotation capacity but it also improved separation selectivity in coal deashing.
The mechanisms of trace element removal during coal cleaning
99102379
Akers, D. J. and Raleigh, C. E., Jr. Coal Prep. (Gordon & Breach), 1998, 19, (3-4). 257-269. As most of the trace elements in coal considered hazardous air pollutant precursors are entirely or primarily associated with mineral matter they are potentially removable using physical coal cleaning processes. Normally, the concentration of trace elements in a coal is reduced when the coal is cleaned to reduce its ash and sulfur content. Through understanding the mechanisms of trace element removal during coal cleaning additional reduction in trace element concentration can be attained. In this paper, the factors that affect trace element reduction are found to be the degree of liberation of trace element-bearing mineral matter, the relative intensity of cleaning, the mode of occurrence of the trace element and the method of cleaning.
Method for reducing water contents in solid materials and/or sludges and apparatus for control and adjustment of filter press 99102380
Bielfeldt, F. B. and Eckhart, K. Jpn. Kokai Tokkyo Koho [98 263,319], (Cl. BOlD25112). 6 Ott 1998, Appl. 97/72,134, 13 pp. (In Japanese) A method for decreasing water content in solid materials, brown coal and/or sludges, is described. It is characterized in generated from the filter press is continuously expanded by an expansion chamber. It is then passed into a steam controlling the expansion speed.
JP 10 263,319 25 Mar 1997, especially raw that the steam passing it into condenser by
99/02391 A novel Sphingomonas capable of selectively desuifurizing dlbenzothiophene for use in biodesulfuriration Darzins, A. and Mrachko, G. T. PCT Int. Appl. WO 98 45,446, (Cl. C12N15/52), 15 Ott 1998, US Appl. 851,089, 5 May 1997, 127 pp. Sphingomonas specific strain AD109, a novel microorganism, is capable of selectively desulfurizing dibenzothiophene. This paper reviews its use in biodesulfurization of fossil fuels, especially coal. The genes for the enzymes involved in the desulfurization of dibenzothiophene were cloned and characterized. The cloned genes for the enzymes can be expressed in a suitable host to enable the costs of coal desulfurization to be lowered. By screening for the ability to use 2-(2-hydroxyphenyl)benzenesulfinate (HPBS) as the sole sulfur source the microorganism was isolated from oil-contaminated soil. The enzyme, responsible for desulfination of HPBS, was purified and characterized by standard methods. The cloning was carried out by screening a Sphingomonas Not1 expression libraty in Escherichia coli for the ability to clear dibenzothiophene 5,5-dioxide plates followed by subcloning to identify the desulfinase gene. 99102382 Optimization flotation centrifuge
of the aeration reactor for a weir
Heidenreich, C. er al. World Congr. Part. Technol. 3, [computer optical disk], 1998, 3134-3144. A new weir flotation centrifuge used for processing anthracite coal and graphite has been developed and is the subject of this study. It applies the counterflow centrifugal separation principle. Aeration and primary mineralization take place outside the separation zone using an aeration reactor with a PTFE frit. Secondary mineralization supported by turbulence is carried out in the separation zone of the centrifuge. This study was aimed at optimizing the process steps taking place in the aeration reactor, especially the investigation of the influence of the porosity and length of the aeration frit and the volume flow ratio of air to suspension. Overall the advantage of the weir flotation centrifuge in comparison to the stationary flotation column and the standard laboratory flotation cell is demonstrated by the results obtained, especially for fine particles.
Preparation of novel pitches by tar air-blowing 99102383 Prada, P. er al. Carbon, 1999, 37, (l), 97-106. High carbon yield coal-tar pitches are prepared by tar air-blowing under pressure (0.5 MPa). The influence of the temperature (275-325”C), reaction time (O-20 h) and air flow (60-120 I h-‘) on pitch composition and properties were monitored by elemental analysis, solubility measurements and Fourier transform infrared spectroscopy. The development of mesophase was monitored in the resultant pitches by optical microscopy of their pyrolysis products obtained at 450°C. Results show that the airblowing of tar, performed under mild conditions, promotes the condensation of molecular components producing cross-linked oligomers, so increasing the yield of the process. The extent of polymerization increased with severity of treatment and resulted in an increase of pitch carbon yield. Moreover, the different properties of prepared pitches offer the possibility to obtain cokes with a wide range of optical textures.
252
Fuel and Energy Abstracts
July 1999
99102384 Process for desulfurization of solid fossil fuels Andres Gimeno, J. M. and Ferrando Navarro, A. C. Span. ES 2.107.383, (Cl. ClOL9/00), 16 Nov 1997, Appl. 9,501,859, 26 Sep 1995, 5 pp. (In Spanish) This desulfurization method comprises mixing the fossil fuel with a desulfurization reagent which contains 57% HI, up to 10% I, 0.2-50% H and an inert gas. This takes place under oxidizing or reducing conditions for 5-15 min, in a closed reactor at l-60 atmospheric pressure, using microwave heating to 25-4Oo”C. Included in the process is an absorption tower to strip and retain the HzS formed during the reaction.
Processes for the sorption of gaseous components at high temperatures (>9OCrC)
99102305
Hubner, K. High Temp. Gas Clean., [Pap. Int. Symp. Exhib. Gas Clean. High Temp./ 3, 1996, 352-363. Edited by Schmidt, E., Institut fur Mechanische Verfahrenstechnik und Mechanik der Universitaet Karlsruhe, Karlsruhe, Germany. Hot gas clean-up is increasingly important as far as the development of novel coal conversion processes using combined gas and steam cycles is concerned. This is not only relevant to the removal of particles, but also to the separation of gaseous pollutants at high temperatures and pressures. The dry removal of acidic gas components (for example SOz. HCI and HF) using calcium compounds is, however, limited by thermodynamic equilibrium. The composition of flue gases from coal conversion means that removal of the hydrogen halides is not viable at temperatures above 800°C. Thermodynamics could be used to achieve the separation of SOz by lime compounds at temperatures up to over 1200°C. However, this reaction is hindered kinetically as a result of sintering effects at temperatures above 900°C. At extreme temperatures, there are no suitable solid agents for the removal of the mentioned pollutants. Theoretically the problems of unsatisfactory thermodynamic equilibrium and kinetic hindering can be overcome by using a mixture of molten salts or oxides. These substances have to fulfil a number of pre-conditions in order for the sorption process to operate successfully, which are detailed. Laboratory and semi-technical scale experiments have achieved separation efficiencies of more than 90% so far. The gas separation process can be combined with corresponding processes to make the removal of particles possible. 99102386
Quality control for roll sleeve of coal pulverizer produced by centrifugal compound casting
Ning, Z. et al. Zhuzao, 1998, (4), 36-38. (In Chinese) This paper examines the roll sleeve of coal pulverizer produced by centrifugal compound casting. Metallurgical and technical factors influencing the quality of double-metal layer and crack formation of the roll sleeve are discussed. The key to quality control of the roll sleeve is suggested to be the control of the metallurgical quality of the double-metal layer and casting stress crack formation prevention.
Rapid devolatilisation of Yallourn brown coal at high pressures and temperatures
99102387
Yeasmin, H. et al. Fuel, 78, (1). 11-24. A pressurized drop-tube furnace was used to study the devolatilization behaviour of Yallourn brown coal. Coal particles of 37-53 /Irn size were devolatilized at pressures of 100, 500 and 1000 kPa. The experiments were carried out at temperatures of 873, 1073 and 1273 K. Residence times were varied from 0.02 to 3 s. Weight loss was calculated based on ash as a tracer. The maximum weight loss due to devolatilization is temperature and pressure dependent. At a particular residence time and pressure, the weight loss increases with an increase in devolatilization temperature. Increasing the pressure not only increases the residence time required to achieve a given level of weight loss, but also reduces the total weight loss attainable at a particular temperature. Weight loss due to devolitilization was fitted by a two-stage first-order kinetic expression. The calculated kinetic parameters are considerably lower than the reported parameters for lignites and bituminous coals. It appears that initial devolatilization of Yallourn brown coal is mainly dominated by very low activation energy. Variation of activation energy with the level of devolatilization was observed. This variation could be partially due to the presence of active sites in the char with different characteristic reactivities.
Reduction of toxic trace element concentrations by physically cleaning three finely-ground coals
99102388
Smit, F. J. er al. Coal Prep. (Gordon & Breach), 1998, 19, (3-4), 231-241. This paper describes a study of an advanced physical coal cleaning process comprising column flotation and selective agglomeration (with recycle heptane bridging liquid) in a 2-t/h process development unit (PDU). The residual concentrations of 12 toxic trace element impurities, including mercury and selenium, in ground Taggart, Indiana VII and Hiawatha coals were determined after they had undergone this process. For each of the trace elements, the reduction in concentration from the amount in the runof-mine (ROM) parent coals and the amount in the washed test coals was also determined, on a heating value basis.