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01435 Combustion behavior of coal under simulated blast furnace conditions
09 Combustion (burners, combustion systems) higher occurrence of valuable saturated and non-saturated hydrocarbons indicated. The matter anisotropy was increased by microscopic research solid carbon products.
is of
Coal and biomass co-combustion on tluidized bed: comparison of circulating and bubbling fluidized bed technologies
99101432
Armesto, L. et al. Proc. Int. Conf. Fluid. Bed Cornbust., 1997, 14, (1) 301311. One of the most promising methods for combustion today is the fluidized bed. its application to boilers is recognized primarily for its low sensitivity to fuel quality and its capacity to limits air pollution. As well as coal combustion this technology is also being used ail over the world for biomass. Nevertheless, there are no results available on the joint utilization of these fuels. The main objective of the proposed paper is to demonstrate the technical feasibility of fluidized bed as a clean technology for the combustion of low grade coal/biomass blends. Expected to improve the conversion of the fossil fuels due to the high volatile content of biomass is its utilization of in blends with low grade coal thus reducing the emissions of SO2 and NO, as well as the emissions of CO2 due to the renewable origin of the biomass. The raw materials used as fuels in the tests are different blends of the following materials. (1) Refuse coal with a heating value of 3658 kJ/ kg (LHV, db) and 79.63% ash content. (2) Low grade coal: lignite with a heating value of 19952 kJ/kg (LHV, db), a sulfur content of 10.32% (db) and 23.70% ash content. (3) Biomass: forestry wastes from wood cleaning whose heating value is 19555 kJ/kg (LHV, db). An absorbent, limestone, has been used for reducing sulfur emissions. Co-combustion tests, at the pilot plant level, have been carried out by using two fluidized bed technologies, circulating and bubbling. In an energy and emission point of view, the object of this paper is to study the clean and efficient use of these resources. The paper collects, analyses and compares combustion test data. 99101433
Combustion and gasification properties of plastics
particles
Zevenhoven, R. et al. .I. Air Waste Manage. Assoc., 1997, 47, (8), 861-870. The paper studies the combustion and gasification behaviour of the most common plastics and compares them with conventional fuels such as coal, peat and wood. The paper aims to provide background data for determining the optimum conditions for co-combustion or co-gasification of a conventional fuel with a certain amount of plastic-derived fuel. Atmospheric or pressurized fluidized bed co-combustion of conventional fuels and plastics are considered to be promising future options. The plastics investigated were poly(ethyiene) (PE), poiy(propyiene) (PP), poiy(styrene) (PS) and poiy(vinyi chloride) (PVC). The reference fuels were Polish bituminous coal, Finnish peat and Finnish pine wood. PE, PP and PS burned like oil. PVC was the only plastic that produced a carbonaceous residue and its time-scales for heating devoiatiiization and char burning were of the same order as those for peat and wood and much shorter for the other plastics studied. An important result is that char from PVC contained cl% chlorine, 99% hydrocarbon. The gasification rate of PVC char (at 1 and 25 bar) was of the same order as that of char from coal.
Combustion and heat transfer in model two-dimen99101434 sional porous burners
Hackert, C. L. et al. Combus?. Flame, 1999, 116, (l/2), 177-191. In order to anaiyse the influence of multi-dimensionaiity on flames within pore scale structures, a two-dimensional model of two simple porous burner geometries is developed. The first geometry simulates a honeycomb burner, in which a ceramic is penetrated by many small, straight, non-connecting passages. The second geometry consists of many small parallel plates aligned with the flow direction. The Monte Carlo method is employed to calculate the viewfactors for radiation heat exchange in the second geometry. This model compares well with experiments on burning rates, operating ranges and radiation output. Heat losses from the burner are found to reduce the burning rate. The flame is shown to be highly twodimensional and limitations of one-dimensional models are discussed. The effects of the material properties on the peak burning rate in these model porous media are examined.
Combustion behavior of coal under simulated blast 99101435 furnace conditions
Hutny, W. P. et al. Combust. Can. ‘96 Conf.: Future Changing Role Combus?. Can. Ef@z. Environ., 1996, Paper30/1-Paper30/14. Both pulverized and granular Canadian coals were assessed for blast furnace injection including their combustibility, char activity and morphoiogy. Pulverized and granular coal char, in both reactivity and granular terms were compared with tuyere coke. The chars were more reactive with higher reaction rate than tuyere. Evaluated are the possibilities of coke replacement. 99101436
bed furnace
Combustion behavior of pulverized coal in a coke
Choi, T.-H. and Chung, S.-K. Hwahok Konghak, 1998, 36, (1), l-7. (In Korean) By using the coke bed experimental furnace, a fundamental investigation on combustion behaviour of pulverized coal has been carried out. In this furnace, experiments are executed with varying of the oxygen enrichment methods, the position of the coal injection lance, coal blends etc. The coal
combustibility of the oxy-coal system that the oxygen was injected with the coal through the oxy-coal lance was about 10% higher than that of the conventional oxygen enrichment method that the oxygen was enriched in the hot stove. When the oxygen content of hot blast was higher than 25% however, the maximum gas temperature in the raceway zone was decreased and combustibility of coal was not increased greatly.
Combustion behavior of residual char from the British coal gasification process in a circulating fluidized bed combustor
99io1437
Juiien, S. et al. Combust. Can. ‘96 Conf: Future Changing Role Combust. Can. Efic. Environ., 1996, (3). l-31. Gasification char, obtained from the pressurized gasifier at British Coal in a pilot scale circulating fluidized bed combustor, had combustion tests carried out on it. Objectives were to determine combustion performance and to produce emissions data for the British Coal gasifier char which is a particular fuel having a very low matter content, a wide particle size distribution and containing CaS to be completely oxidized to CaSO+ The char could be burned with combustion efficiencies in excess of 96.5%. The combustion was stable provided that a bed temperature was maintained at a minimum of approximately 880°C. Higher combustion efficiencies can likely be expected in commercial operation with higher single pass residence times. There were no sintering problems with a silica sand bed despite the relatively high combustion temperature. Emissions of carbon monoxide in the pilot plant were high, typically in excess of 400 ppmv. This may be attributed to the short gas residence time at high temperature in the pilot CFB combustor and cyclones. The CO emissions would be reduced by an appropriate increase in the gas residence time in commercial designs, beyond the pilot value of 1.0 s. The same change would likely enhance combustion efficiency. Sulfur dioxide emissions from combustion of the char are associated with re-release of sulfur captured in the gasifier as calcium sulfide. With limestone addition 1.7% of captured sulfur was rereleased. There was a substantial effect of temperature spikes on evolution of SOz. The fractional conversion of fuel nitrogen in the char to NO, varied from between 8.5 to 13.5% depending upon the temperature and limestone addition The NO, emissions increased with temperature. Nitrous oxide emission levels varied from 137 to 85 ppm, approximately 50% of the NO, value.
Compared CFB combustion and desulfurization of lignite and bituminous coal
99101438
Jinescu, G. et al. Hung. .I. Ind. Chem., 1998, 26, (2), 135-139. Low-grade coal and bituminous coal had a series of circulating fluidized bed combustion (CFBC) and desuifurization tests carried out on them. The tests focused on the combustion of several lignite and bituminous coal types to develop a better CFBC technology. The pilot plant used for the experiments was briefly described. The measured parameters (temperatures, pollutant emissions) for the different coals were compared. The desuifurization was performed with addition of limestone. It was discovered that the combustion and desuifurization of different fuel types can be performed on the same CFBC plant with high efficiency.
Comparison of large- and small-scale circulating 99101439 fluidized bed combustors with respect to pollutant formation and reduction for different fuels
Knobig, T. et al. Fuel, 1998, 77, (14), 1635-1642. This paper investigates the scale-up problem of circulating fluidized bed combustors with particular respect to emissions. Comparative combustion experiments were performed in an industrial-size combustor and in a laboratory-scale facility. The axial concentration profiles of oxygen, carbon monoxide, nitric oxide, nitrous oxide and ammonia along the riser height, obtained during the combustion of wood, peat and coal under conditions of equal fuel bed material, solid hold-up and gas residence time, in both combustors were compared. They showed a basic similarity indicating that suitably sized and operated laboratory-scale combustors may indeed be valuable tools for the investigation of combustion phenomena. However, some significant deviations of the profiles can be recognized too. These deviations are caused by three-dimensional effects in the large-scale combustor and highlight the limitations of small-scale experiments.
Current status and prospect of coal combustion technology in developing nations
99101440
Sadakata, M. Kagaku Kegaku no Shinpe, 1997, 31, 131-147. (In Japanese) This review focuses on the current status and prospect of coal combustion technology and related environmental problems.
99io1441 Effect of BioLime atomization characteristics on simultaneous NO. and SO2 capture in coal combustion systems. Pisupati, S. V. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (3) 20-32. On the SOz and NO, reduction performance, this paper discusses the effect of the atomization characteristics of BioLime (a biomass-based pollution control material developed by DynaMotive Technologies Corporation). The tests were conducted in a 500,000 Btulh down fired combustor at the Pennsylvania State University firing pulverized, high-sulfur coal. Investigated was the effect of the temperature at the injection location, atomization air pressure and the influence of the delay in the supply of air for the combustion of the BioLime. Atomization was performed using both air and nitrogen. A simultaneous reduction of 90% of the SOz and
Fuel and Energy Abstracts
March 1999
145
is of
Coal and biomass co-combustion on tluidized bed: comparison of circulating and bubbling fluidized bed technologies
99101432
Armesto, L. et al. Proc. Int. Conf. Fluid. Bed Cornbust., 1997, 14, (1) 301311. One of the most promising methods for combustion today is the fluidized bed. its application to boilers is recognized primarily for its low sensitivity to fuel quality and its capacity to limits air pollution. As well as coal combustion this technology is also being used ail over the world for biomass. Nevertheless, there are no results available on the joint utilization of these fuels. The main objective of the proposed paper is to demonstrate the technical feasibility of fluidized bed as a clean technology for the combustion of low grade coal/biomass blends. Expected to improve the conversion of the fossil fuels due to the high volatile content of biomass is its utilization of in blends with low grade coal thus reducing the emissions of SO2 and NO, as well as the emissions of CO2 due to the renewable origin of the biomass. The raw materials used as fuels in the tests are different blends of the following materials. (1) Refuse coal with a heating value of 3658 kJ/ kg (LHV, db) and 79.63% ash content. (2) Low grade coal: lignite with a heating value of 19952 kJ/kg (LHV, db), a sulfur content of 10.32% (db) and 23.70% ash content. (3) Biomass: forestry wastes from wood cleaning whose heating value is 19555 kJ/kg (LHV, db). An absorbent, limestone, has been used for reducing sulfur emissions. Co-combustion tests, at the pilot plant level, have been carried out by using two fluidized bed technologies, circulating and bubbling. In an energy and emission point of view, the object of this paper is to study the clean and efficient use of these resources. The paper collects, analyses and compares combustion test data. 99101433
Combustion and gasification properties of plastics
particles
Zevenhoven, R. et al. .I. Air Waste Manage. Assoc., 1997, 47, (8), 861-870. The paper studies the combustion and gasification behaviour of the most common plastics and compares them with conventional fuels such as coal, peat and wood. The paper aims to provide background data for determining the optimum conditions for co-combustion or co-gasification of a conventional fuel with a certain amount of plastic-derived fuel. Atmospheric or pressurized fluidized bed co-combustion of conventional fuels and plastics are considered to be promising future options. The plastics investigated were poly(ethyiene) (PE), poiy(propyiene) (PP), poiy(styrene) (PS) and poiy(vinyi chloride) (PVC). The reference fuels were Polish bituminous coal, Finnish peat and Finnish pine wood. PE, PP and PS burned like oil. PVC was the only plastic that produced a carbonaceous residue and its time-scales for heating devoiatiiization and char burning were of the same order as those for peat and wood and much shorter for the other plastics studied. An important result is that char from PVC contained cl% chlorine, 99% hydrocarbon. The gasification rate of PVC char (at 1 and 25 bar) was of the same order as that of char from coal.
Combustion and heat transfer in model two-dimen99101434 sional porous burners
Hackert, C. L. et al. Combus?. Flame, 1999, 116, (l/2), 177-191. In order to anaiyse the influence of multi-dimensionaiity on flames within pore scale structures, a two-dimensional model of two simple porous burner geometries is developed. The first geometry simulates a honeycomb burner, in which a ceramic is penetrated by many small, straight, non-connecting passages. The second geometry consists of many small parallel plates aligned with the flow direction. The Monte Carlo method is employed to calculate the viewfactors for radiation heat exchange in the second geometry. This model compares well with experiments on burning rates, operating ranges and radiation output. Heat losses from the burner are found to reduce the burning rate. The flame is shown to be highly twodimensional and limitations of one-dimensional models are discussed. The effects of the material properties on the peak burning rate in these model porous media are examined.
Combustion behavior of coal under simulated blast 99101435 furnace conditions
Hutny, W. P. et al. Combust. Can. ‘96 Conf.: Future Changing Role Combus?. Can. Ef@z. Environ., 1996, Paper30/1-Paper30/14. Both pulverized and granular Canadian coals were assessed for blast furnace injection including their combustibility, char activity and morphoiogy. Pulverized and granular coal char, in both reactivity and granular terms were compared with tuyere coke. The chars were more reactive with higher reaction rate than tuyere. Evaluated are the possibilities of coke replacement. 99101436
bed furnace
Combustion behavior of pulverized coal in a coke
Choi, T.-H. and Chung, S.-K. Hwahok Konghak, 1998, 36, (1), l-7. (In Korean) By using the coke bed experimental furnace, a fundamental investigation on combustion behaviour of pulverized coal has been carried out. In this furnace, experiments are executed with varying of the oxygen enrichment methods, the position of the coal injection lance, coal blends etc. The coal
combustibility of the oxy-coal system that the oxygen was injected with the coal through the oxy-coal lance was about 10% higher than that of the conventional oxygen enrichment method that the oxygen was enriched in the hot stove. When the oxygen content of hot blast was higher than 25% however, the maximum gas temperature in the raceway zone was decreased and combustibility of coal was not increased greatly.
Combustion behavior of residual char from the British coal gasification process in a circulating fluidized bed combustor
99io1437
Juiien, S. et al. Combust. Can. ‘96 Conf: Future Changing Role Combust. Can. Efic. Environ., 1996, (3). l-31. Gasification char, obtained from the pressurized gasifier at British Coal in a pilot scale circulating fluidized bed combustor, had combustion tests carried out on it. Objectives were to determine combustion performance and to produce emissions data for the British Coal gasifier char which is a particular fuel having a very low matter content, a wide particle size distribution and containing CaS to be completely oxidized to CaSO+ The char could be burned with combustion efficiencies in excess of 96.5%. The combustion was stable provided that a bed temperature was maintained at a minimum of approximately 880°C. Higher combustion efficiencies can likely be expected in commercial operation with higher single pass residence times. There were no sintering problems with a silica sand bed despite the relatively high combustion temperature. Emissions of carbon monoxide in the pilot plant were high, typically in excess of 400 ppmv. This may be attributed to the short gas residence time at high temperature in the pilot CFB combustor and cyclones. The CO emissions would be reduced by an appropriate increase in the gas residence time in commercial designs, beyond the pilot value of 1.0 s. The same change would likely enhance combustion efficiency. Sulfur dioxide emissions from combustion of the char are associated with re-release of sulfur captured in the gasifier as calcium sulfide. With limestone addition 1.7% of captured sulfur was rereleased. There was a substantial effect of temperature spikes on evolution of SOz. The fractional conversion of fuel nitrogen in the char to NO, varied from between 8.5 to 13.5% depending upon the temperature and limestone addition The NO, emissions increased with temperature. Nitrous oxide emission levels varied from 137 to 85 ppm, approximately 50% of the NO, value.
Compared CFB combustion and desulfurization of lignite and bituminous coal
99101438
Jinescu, G. et al. Hung. .I. Ind. Chem., 1998, 26, (2), 135-139. Low-grade coal and bituminous coal had a series of circulating fluidized bed combustion (CFBC) and desuifurization tests carried out on them. The tests focused on the combustion of several lignite and bituminous coal types to develop a better CFBC technology. The pilot plant used for the experiments was briefly described. The measured parameters (temperatures, pollutant emissions) for the different coals were compared. The desuifurization was performed with addition of limestone. It was discovered that the combustion and desuifurization of different fuel types can be performed on the same CFBC plant with high efficiency.
Comparison of large- and small-scale circulating 99101439 fluidized bed combustors with respect to pollutant formation and reduction for different fuels
Knobig, T. et al. Fuel, 1998, 77, (14), 1635-1642. This paper investigates the scale-up problem of circulating fluidized bed combustors with particular respect to emissions. Comparative combustion experiments were performed in an industrial-size combustor and in a laboratory-scale facility. The axial concentration profiles of oxygen, carbon monoxide, nitric oxide, nitrous oxide and ammonia along the riser height, obtained during the combustion of wood, peat and coal under conditions of equal fuel bed material, solid hold-up and gas residence time, in both combustors were compared. They showed a basic similarity indicating that suitably sized and operated laboratory-scale combustors may indeed be valuable tools for the investigation of combustion phenomena. However, some significant deviations of the profiles can be recognized too. These deviations are caused by three-dimensional effects in the large-scale combustor and highlight the limitations of small-scale experiments.
Current status and prospect of coal combustion technology in developing nations
99101440
Sadakata, M. Kagaku Kegaku no Shinpe, 1997, 31, 131-147. (In Japanese) This review focuses on the current status and prospect of coal combustion technology and related environmental problems.
99io1441 Effect of BioLime atomization characteristics on simultaneous NO. and SO2 capture in coal combustion systems. Pisupati, S. V. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (3) 20-32. On the SOz and NO, reduction performance, this paper discusses the effect of the atomization characteristics of BioLime (a biomass-based pollution control material developed by DynaMotive Technologies Corporation). The tests were conducted in a 500,000 Btulh down fired combustor at the Pennsylvania State University firing pulverized, high-sulfur coal. Investigated was the effect of the temperature at the injection location, atomization air pressure and the influence of the delay in the supply of air for the combustion of the BioLime. Atomization was performed using both air and nitrogen. A simultaneous reduction of 90% of the SOz and
Fuel and Energy Abstracts
March 1999
145