- Email: [email protected]
00638 The fate of nitrogen during pyrolysis of German low rank coals—a parameter study
01 00100633 Combustion and gasification characteristics of pulverized coal using high-temperature air Hanaoka, R. et al. FACT (Ani. Sot. Mech. Eng.), 1998, 22, (Proceedings of the 1998 International Joint Power Generation Conference, Vol. 1, 1998) 495-500. Laboratory-scale combustion and gasification tests of coal were conducted in a drop tube furnace (200 mm in inside diameter and 2000 mm in length) in order to confirm performance of high-temperature-air combustion of pulverized coal. Air temperature and oxygen concentration in the air were varied and the furnace was heated up to 1300” by a ceramic heater. A hightemperature air preheater utilizing the high cycle regenerative combustion system was used to obtain high-temperature combustion air. The results showed that NO, emission was reduced when pulverized coal was fired with high-temperature-air. Additionally, lower oxygen concentration in combustion air diluted by nitrogen slightly decreased NO, emission, while it became higher under staging condition.
Dephosphorization method of coal 00100634 Masaharu, I. and Taizo, T. Jpn. Kokai Tokkyo Koho JP 11 43,682 [99 43,682] (Cl. ClOLS/OO), I6 February 1999, Appl. 971202,829, 29 July 1997, 4pp. (In Japanese) A method of phosphorus removal from coal involves coal coming into contact with a liquid organic acid. for example, oxalic acid, acetic acid and fumaric acid.
Desulfurtzation of chemical pretreated coals by 00100635 rapid pyrolysis Taubouchi, N. et al. Sckitan Kagaku Kaigr Happyo Ronhunshu, 1997, 34, 199-202. (In Japanese) A series of studies on the development of efficient cleaning processes of coal is reported, the purpose of which is to clarify effective desulfurization conditions by elucidating sulfur behaviour in rapid pyrolysis with various pretreatments. Experimental results showed that combined processes of rapid pyrolysis with nitric acid and potassium hydroxide pretreatments were effective for sulfur reduction from lignite and subbituminous coals, respectively. A series of treatments of Tetralin and nitric acid caused significant sulfur removal for bituminous coal. It can be concluded that the chemical pretreatments were required for efficient coal desulfurization.
Development of advanced process for direct coal 00100636 liquefaction. 1. Transformation of iron catalyst to active phase pyrrhotite Tazawa, K. et al. Sekitm Kagaku Kaigi Happyo Ronhmrshu, 1997. 34, 15 l154. (In Japanese) The transformation of iron catalyst to active phase pyrrhotite was investigated in relation to the catalytic activity. It was found that the yFeOOH transformed to pyrrhotite at lower temperature than pyrite. In addition, pyrrhotite from ?-FeOOH had smaller crystallites with a higher surface area than that from pyrite. Moreover, a large consumption of gaseous hydrogen was observed’during the heating stage up to 450” in the case of 7-FeOOH catalyst, while the consumption of hydrogen in the case of pyrite catalyst was small. These results suggested that ?-FeOOH had a good catalytic activity for hydrogen transfer to radical fragments in initial stage of coal liquefaction.
Effect of catalyst addition on co-liquefaction 00100637 process of coal and biomass in supercritical water Yokura, H. er al. Sekitan Kagaku Kaigi Happy0 Ronbunshu, 1997, 34, 6972. (In Japanese) A mixture of coal and cellulose was liquefied in supercritical water at 400” and 25 MPa. The yields of residue, liquid and gas were compared with the result of separate liquefaction of coal and cellulose. The results indicate that co-liquefaction does not reduce the residue yield, but leads to a higher liquid yield. The addition of nickel catalyst results in a higher gas yield and a smaller residue yield. Hydrogen is produced by nickel catalysts, but is not utilized in coal liquefaction effectively.
The fate of nitrogen during pyrolysis of German low OOlOO638 rank coals-a parameter study Friebel, J. and Kopsel, R. F. W. Fuel, 1999, 78, (8),923-932. Proceeding from the knowledge of the functional forms of nitrogen in coals, it should be possible to draw conclusions on the mechanisms of its release during devolatilization. Pyrolysis experiments were carried out with a series of lignite from the main German mining districts in a temperature range of 673-1173 K. The coals nitrogen functions and the obtained chars were determined by XPS. The nitrogen content of the residual pyrolysis chars was found to be dependent on a wide variety of parameters: coal type, temperature, residence time and mineral matter. An increasing N/C ratio was detected for chars obtained under conditions of oxopyrolysis. The conversion of fuel-bound nitrogen to NO,-precursors (HCN. NHx) is also strongly dependent on coal type. The mineral matter of the parent coals was found to affect both the primary devolatilization process and the reaction paths to form ammonia. The balance of the nitrogen distribution during is pyrolysis shows a large amount of N Z to which the coal-nitrogen converted.
Solid fuels (preparation)
00100639 Formation of N2 during coal gasification with carbon dioxide Wu, Z. and Ohtsuka, Y. Sekitarl Kagakrr Kuigi Happyo Ronh~rnvhu, 1997. 34, 243-246. (In Japanese) An investigation into the formation of Nz from seven coals during carbon dioxide gasification at 1000°C in a fixed bed quartz reactor. NZ was found to be the major N-containing product, irrespective of coal type. NZ yield increases as coal conversion increases for all the coals, however the yield is dependent on coal type when compared at the same level of coal conversion. NT yield was also evaluated on the basis of char-N remaining after devolatthzation preceding char gasification. The results indicate that the yield is independent of coal type and determined only by the extent of gasification.
00100640 Froth flotation: preparation of a laboratory standard Brown, D. W. and Hall, S. T. F~rel. 1999, 78, (14). lh2l-163tl. In evaluating the separation of coal from slurries of fine solids by froth flotation, it is necessary to work to a standard method to ensure that the procedure, on the same sample, can be repeated by others and the same results obtained. In a number of countries the standard procedure is produced and distributed by the International Standards Organization (ISO) working through its member countries. In the preparation of a froth flotation standard, two different techniques from two countries (Australia and Great Britain) have been proposed. These procedures. known as the ‘tree’ and ‘release’ analyses respectively, differ in the laboratory technique and presentation of results. In order to assist in the debate of which of the procedures should be adopted as the basis for the International Standard. a short programme of comparative work was undertaken to evaluate the different methods. Samples of coal slurries from Australia, Great Britain and South Africa were evaluated using the Australian and British procedures. The work undertaken is described detailing the preparation of the samples, test procedures and differences between the two techniques. The results showed that the two techniques produced similar results with the ‘Release Analysis’ giving more detail at the cleaner (low ash) end of the curve and the ‘Tree Analysis’ more data for the middle (medium ash-higher yield) part of the curve. The results indicated that the technique chosen would be dependent upon the information required from the flotation analysis, i.e. the British ‘Release Analysis‘ for the cleaner coal data and the Australian ‘Tree Analysis’ for higher ash fractions.
00100641 Gasification reaction of coal and char in the circulating fluidized bed (CFB) I. Effect of operating gas velocity and solid circulating rate on gasification reaction in CFB Fang, Y. et al. Ranliao Huaxue Xuehao, 1998, 26. (6). 521-525. (In Chinese) The gasification reaction of fly ash of Xishan coking coal was studied using an experimental circulating fluidized bed (CFB) reactor. The CFB gasifier is heated by electric heaters and consists of a r’iser (48 mm in diameter x 3560 mm), a solids-gas separator system and a recirculation column (68 mm in diameter). The fly ash was found to react with carbon dioxide at different gas velocity and solid circulating rates. The test results show that the carbon monoxide concentration, carbon conversion and gasification efficiency increase when gas velocity decrease under consistent fuel feed rate. This is attributed mainly to the increasing solids holdup. The reactant gas residence time increased from 2.82 to 3.73 s when the gas velocity decreased from 1.2 to 0.95 m/s. Under identical conditions, the solids holdup in the bed increases with increasing solid circulating rate. Therefore, more solid particles take part in the gasification reaction and carbon monoxide concentration and carbon conversion increase. The axial carbon monoxide concentration profile has a corresponding relation with that of the axial solid particle concentration.
00100642 Kinetic study of conversion of Illinois #6 coal in Tetralin at relatively mild temperature Nakada, M. Sekitan Kagaku Kaigi Happy0 Ronbwwhu, 1997, 34. 1 I l-l 14. (In Japanese) Using tetralin as the solvent, Illinois #h coal was converted to pyridine soluble fraction at 250-300°C and the pseudo first order rate constants of this reaction and activation energy were measured. The activation energy (Ea) was 35.3 kcal, and from this value the conversion is inferred to proceed through chemical bond succession.
00100643 Losses in diagonal MHD generator Bhadoria, B. S. and Chandra, A. Energy Convers. & Manage., 1999, 40, (18), 1985-1995. Losses in an MHD generator not only reduce the power output but also degrade it. The losses due to heat, friction and leakage through insulatingwall/slag have been analysed for the diagonal generator for better control and performance. The losses due to leakage are higher than the heat and friction losses. The effect of wall temperature on losses is significant. The heat and friction losses decrease with increase in wall temperature, whereas the leakage losses increase with increase in wall temperature. The slag losses reduce power output from the channel drastically.
Fuel
and
Energy
Abstracts
March 2000
75
Dephosphorization method of coal 00100634 Masaharu, I. and Taizo, T. Jpn. Kokai Tokkyo Koho JP 11 43,682 [99 43,682] (Cl. ClOLS/OO), I6 February 1999, Appl. 971202,829, 29 July 1997, 4pp. (In Japanese) A method of phosphorus removal from coal involves coal coming into contact with a liquid organic acid. for example, oxalic acid, acetic acid and fumaric acid.
Desulfurtzation of chemical pretreated coals by 00100635 rapid pyrolysis Taubouchi, N. et al. Sckitan Kagaku Kaigr Happyo Ronhunshu, 1997, 34, 199-202. (In Japanese) A series of studies on the development of efficient cleaning processes of coal is reported, the purpose of which is to clarify effective desulfurization conditions by elucidating sulfur behaviour in rapid pyrolysis with various pretreatments. Experimental results showed that combined processes of rapid pyrolysis with nitric acid and potassium hydroxide pretreatments were effective for sulfur reduction from lignite and subbituminous coals, respectively. A series of treatments of Tetralin and nitric acid caused significant sulfur removal for bituminous coal. It can be concluded that the chemical pretreatments were required for efficient coal desulfurization.
Development of advanced process for direct coal 00100636 liquefaction. 1. Transformation of iron catalyst to active phase pyrrhotite Tazawa, K. et al. Sekitm Kagaku Kaigi Happyo Ronhmrshu, 1997. 34, 15 l154. (In Japanese) The transformation of iron catalyst to active phase pyrrhotite was investigated in relation to the catalytic activity. It was found that the yFeOOH transformed to pyrrhotite at lower temperature than pyrite. In addition, pyrrhotite from ?-FeOOH had smaller crystallites with a higher surface area than that from pyrite. Moreover, a large consumption of gaseous hydrogen was observed’during the heating stage up to 450” in the case of 7-FeOOH catalyst, while the consumption of hydrogen in the case of pyrite catalyst was small. These results suggested that ?-FeOOH had a good catalytic activity for hydrogen transfer to radical fragments in initial stage of coal liquefaction.
Effect of catalyst addition on co-liquefaction 00100637 process of coal and biomass in supercritical water Yokura, H. er al. Sekitan Kagaku Kaigi Happy0 Ronbunshu, 1997, 34, 6972. (In Japanese) A mixture of coal and cellulose was liquefied in supercritical water at 400” and 25 MPa. The yields of residue, liquid and gas were compared with the result of separate liquefaction of coal and cellulose. The results indicate that co-liquefaction does not reduce the residue yield, but leads to a higher liquid yield. The addition of nickel catalyst results in a higher gas yield and a smaller residue yield. Hydrogen is produced by nickel catalysts, but is not utilized in coal liquefaction effectively.
The fate of nitrogen during pyrolysis of German low OOlOO638 rank coals-a parameter study Friebel, J. and Kopsel, R. F. W. Fuel, 1999, 78, (8),923-932. Proceeding from the knowledge of the functional forms of nitrogen in coals, it should be possible to draw conclusions on the mechanisms of its release during devolatilization. Pyrolysis experiments were carried out with a series of lignite from the main German mining districts in a temperature range of 673-1173 K. The coals nitrogen functions and the obtained chars were determined by XPS. The nitrogen content of the residual pyrolysis chars was found to be dependent on a wide variety of parameters: coal type, temperature, residence time and mineral matter. An increasing N/C ratio was detected for chars obtained under conditions of oxopyrolysis. The conversion of fuel-bound nitrogen to NO,-precursors (HCN. NHx) is also strongly dependent on coal type. The mineral matter of the parent coals was found to affect both the primary devolatilization process and the reaction paths to form ammonia. The balance of the nitrogen distribution during is pyrolysis shows a large amount of N Z to which the coal-nitrogen converted.
Solid fuels (preparation)
00100639 Formation of N2 during coal gasification with carbon dioxide Wu, Z. and Ohtsuka, Y. Sekitarl Kagakrr Kuigi Happyo Ronh~rnvhu, 1997. 34, 243-246. (In Japanese) An investigation into the formation of Nz from seven coals during carbon dioxide gasification at 1000°C in a fixed bed quartz reactor. NZ was found to be the major N-containing product, irrespective of coal type. NZ yield increases as coal conversion increases for all the coals, however the yield is dependent on coal type when compared at the same level of coal conversion. NT yield was also evaluated on the basis of char-N remaining after devolatthzation preceding char gasification. The results indicate that the yield is independent of coal type and determined only by the extent of gasification.
00100640 Froth flotation: preparation of a laboratory standard Brown, D. W. and Hall, S. T. F~rel. 1999, 78, (14). lh2l-163tl. In evaluating the separation of coal from slurries of fine solids by froth flotation, it is necessary to work to a standard method to ensure that the procedure, on the same sample, can be repeated by others and the same results obtained. In a number of countries the standard procedure is produced and distributed by the International Standards Organization (ISO) working through its member countries. In the preparation of a froth flotation standard, two different techniques from two countries (Australia and Great Britain) have been proposed. These procedures. known as the ‘tree’ and ‘release’ analyses respectively, differ in the laboratory technique and presentation of results. In order to assist in the debate of which of the procedures should be adopted as the basis for the International Standard. a short programme of comparative work was undertaken to evaluate the different methods. Samples of coal slurries from Australia, Great Britain and South Africa were evaluated using the Australian and British procedures. The work undertaken is described detailing the preparation of the samples, test procedures and differences between the two techniques. The results showed that the two techniques produced similar results with the ‘Release Analysis’ giving more detail at the cleaner (low ash) end of the curve and the ‘Tree Analysis’ more data for the middle (medium ash-higher yield) part of the curve. The results indicated that the technique chosen would be dependent upon the information required from the flotation analysis, i.e. the British ‘Release Analysis‘ for the cleaner coal data and the Australian ‘Tree Analysis’ for higher ash fractions.
00100641 Gasification reaction of coal and char in the circulating fluidized bed (CFB) I. Effect of operating gas velocity and solid circulating rate on gasification reaction in CFB Fang, Y. et al. Ranliao Huaxue Xuehao, 1998, 26. (6). 521-525. (In Chinese) The gasification reaction of fly ash of Xishan coking coal was studied using an experimental circulating fluidized bed (CFB) reactor. The CFB gasifier is heated by electric heaters and consists of a r’iser (48 mm in diameter x 3560 mm), a solids-gas separator system and a recirculation column (68 mm in diameter). The fly ash was found to react with carbon dioxide at different gas velocity and solid circulating rates. The test results show that the carbon monoxide concentration, carbon conversion and gasification efficiency increase when gas velocity decrease under consistent fuel feed rate. This is attributed mainly to the increasing solids holdup. The reactant gas residence time increased from 2.82 to 3.73 s when the gas velocity decreased from 1.2 to 0.95 m/s. Under identical conditions, the solids holdup in the bed increases with increasing solid circulating rate. Therefore, more solid particles take part in the gasification reaction and carbon monoxide concentration and carbon conversion increase. The axial carbon monoxide concentration profile has a corresponding relation with that of the axial solid particle concentration.
00100642 Kinetic study of conversion of Illinois #6 coal in Tetralin at relatively mild temperature Nakada, M. Sekitan Kagaku Kaigi Happy0 Ronbwwhu, 1997, 34. 1 I l-l 14. (In Japanese) Using tetralin as the solvent, Illinois #h coal was converted to pyridine soluble fraction at 250-300°C and the pseudo first order rate constants of this reaction and activation energy were measured. The activation energy (Ea) was 35.3 kcal, and from this value the conversion is inferred to proceed through chemical bond succession.
00100643 Losses in diagonal MHD generator Bhadoria, B. S. and Chandra, A. Energy Convers. & Manage., 1999, 40, (18), 1985-1995. Losses in an MHD generator not only reduce the power output but also degrade it. The losses due to heat, friction and leakage through insulatingwall/slag have been analysed for the diagonal generator for better control and performance. The losses due to leakage are higher than the heat and friction losses. The effect of wall temperature on losses is significant. The heat and friction losses decrease with increase in wall temperature, whereas the leakage losses increase with increase in wall temperature. The slag losses reduce power output from the channel drastically.
Fuel
and
Energy
Abstracts
March 2000
75