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01472 Combustion in rotary tube furnaces: modelling, operation, and technical institution studies
09 Towards controlling dioxins emissions from power 96lO1463 boilers fuelled with salt-laden wood waste Luthe, C. et al. Chemosphere, 1997, 35, (3), 557-574. Potential control technologies for dioxins emissions from a power boiler fuelled with salt-laden wood waste have been addressed by investigating these emissions. Whereas a reduction in stack particulate levels does not preclude a corresponding reduction in dioxin emissions, good combustion conditions, in combination with an efficient secondary cbllection device for particulate removal, were found to offer effective control. Minimization of dioxin formation at source was addressed with a preliminary assessment of the possible beneficial effect of an attenuated chlorine/sulfur ratio, the results of which were encouraging. A more accurate assessment requires additional trials to eliminate any possible memory effects.
Combustion (burners, combustion systems)
Clrculatlng fluidited-bed combustion of Korean 98/M 466 anthracite Shun, D. et al. Hwahak Konghak, 1996, 34, (3), 321-326. (In Korean) A Korean anthracite of heating value of 4529 kcal/kg and ash content of 38% was studied in a circulating fluidized bed test unit with regard to its combustion characteristics. Feed coal was received from the mines of Samchuk province and sized to average diameter of 0.39 mm. The effect of coal feed rate on temperature profiles, the effect of excess air on combustion efficiency, sorbent effect on desulfurization, and the effect of operating variables on the emission of SO, and NO, were monitored throughout. Highest combustion efficiency of 96% was attained at the excess air ratio of 15%. Sulfur retention of 92% was achieved at a Ca/S mole ratio of 2.3. Carbon monoxide emissions varied between 210-720 ppm according to combustor temperature. Conversion of fuel nitrogen to NO, varied 4-10% by primary air ratio.
Combustion and emission characteristics of high96lO1469 moisture coal in FBC
09
COMBUSTION Burners, Combustion
Systems
Analysis for radiative heat transfer in a circulating 96lOl464 fluidized bed
Steward, F. R. et al. Proc. Inl. Conf. Fluid. Bed Cornbust., 1995, 13, (l), 507-513. For a number of different assumptions, the radiative heat transfer from the particles within a circulating fluidized bed was determined. Based on temperature profiles measured in an operating circulating fluidized bed burning coal, a procedure for predicting the radiative transfer from the solid particles to a cold wall is recommended. Approximately 59% of the total heat transfer to the wall in a circulating fluidized bed combustor is made up of the radiative transfer from the solid particles to a cold wall.
An analysis of four years of operation of the 70 MW 96fOl466 TIDD PFBC demonstration plant Mudd, M. J. and Reinhart, W. P. Proc. Inl. Conf. Fluid. Bed Cornbust., 1995, 13, (2), 925-933. Since its launch in November 1990, the 70 MW, Tidd PFBC Demonstration Plant in Brilliant, Ohio, currently the only operating PFBC Plant in the US, has now operated for four years. The plant has provided invaluable experience concerning the design and operation of the systems required to support PFBC technology and operating data necessary to commercialize PFBC combined-cycle technology at both the 200 MW thermal (70 MWe) scale, and the 800 MW thermal (350 MWe) scale. A summary is provided of the operational experience with the plant, along with key data associated with its operation.
Calculation of average volatile flame temperature of 96lOl466 oil shale particle during fluidized bed combustion Wang, G. et al. Ranshao Kexue Yu Jishu, 1995, 1, (4), 354-359. (In Chinese) It is suggested that the fluidized bed combustion of oil shale may be seriously affected by the temperature of the flame from combustion of volatile matter. The oil shale is fed to a fluidized-bed combustor causing devolatilization to occur and a diffusion flame sheet to form. The energy feedback from the flame, at a higher temperature than that of air, enhances the rate of subsequent devolatilization. An analysis solution for the average flame temperature was derived by taking the chemical reaction in the flame sheet into account, coupling heat transfer with mass transfer between the flame sheet and the particle surface and adopting the Schwab-Zeldovich transformation approach. Good agreement was discovered between the calculated results and the experimental data.
Changes of nitrogen forms during pyrolysis of coal 96lOl467 and an effect of iron loaded on coal
Zhu, Z. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1995, 12, 767-177. Both in the absence and presence of iron, the distribution and chemical changes in nitrogen forms in two demineralized Chinese coals during pyrolysis were examined. XPS analysis with curve resolution was psed to characterize nitrogen forms; the dominant nitrogen form in the demineralized coal before pyrolysis was pyrrolic. For Fe-containing coals, a significant increase in the relative amount of pyridinic nitrogen was observed after pyrolysis. Similarly, for most Fe-containing coals, there was also a conversion from quaternary to pyridinic nitrogen, although it is possible that quaternary nitrogen exists in pyrrolic form associated with oxygen functional groups before coking and is converted to true pyrrolic form. Alternatively, pyridinic nitrogen may be converted to gaseous Ncontaining molecules during pyrolysis.
Wei, X. er al. Ranshao Kexue Yu Jishu, 1997, 3, (3), 264-269. (In Chinese) This study describes the combustion and emission characteristics of high moisture coal in a fluidized bed reactor. The results indicate that the moisture and the air-fuel ratio have significant effect on the combustion and emission of high moisture coal. With increasing moisture, bed temperature and NO,, SO, emissions decrease. The air-fuel ratio has an optimal value, at which the bed temperature is maximum With increasing the ratio, NO, and SO, emissions increase. The results obtained with varying air-fuel ratio for the combustion of dry coal are similar to those for the combustion of high moisture coal.
Combustion and asification behaviors of plastics 96lo1470 injected into raceway of blast Burnace Asanuma, M. et al. Tersu to Hagane, 1997,83, (lo), 617-622. (In Japanese) The drop tube furnace, raceway hot model and scrap melting shaft furnace have been used for the investigation of the combustion and gasification behaviour of plastics. A single plastic was combusted in the drop tube furnace at around 1200°C and the burning rate of coarse plastic was found to be slower than that of pulverized coal. In the raceway hot model and scrap melting shaft furnace with the plastics injection, however, the combustion efficiency of plastics was much higher than that of pulverized coal in spite of coarse particle. Moreover, the gas composition and temperature distribution in the raceway during the plastics injection were similar to those of all coke operation. The combustion mechanism of coarse plastics was different from that of pulverized coal. These results inferred that the residence time of coarse plastics in the raceway was longer than that of pulverized coal or fine particle. The circulation model of coarse plastic particle in the raceway was newly investigated and a theoretical evaluation of the combustion efficiency of plastics was carried out. The results calculated by the circulation model agreed with those of the hot model experiments.
96lo1471 Combustion characteristics of intensively cleaned coal fractions. Effect of mineral matter
Rubiera, F. et al. DGMK Tagungsber., 1997, 9703 (Proceedings ICCS ‘97, Volume 2), 1003-1006. Intensively cleaned coal was combusted to test its effect. Samples with ash contents varying from 2 to 39% were obtained after density separation. Temperature-programmed combustion and isothermal gasification in air were used to measure the reactivities of the parent coal and the cleaned fractions. Coal and char reactivities increased with increasing ash content of the samples. Thermal analysis -mass spectrometry of the low-temperature ashes was also carried out in order to study the reactions of coal minerals under combustion conditions.
96!01472 Combustion in rotary tube furnaces: modelling, operation, and technical institution studies Stapf, D. et al. VDI-Ber., 1997, 1313, 157-162. (In German) Combustion in a rotary-tube furnace was simulated with a gas-phase model. The model took into account the pyrolysis and solids combustion processes. When solids are introduced, the deciding uncertainty factor in the model is related to the combustion kinetic data. This requires an additional model for heat and mass transfer between the combusting coke layer and the underlying solid bed.
Combustion of secondary products from metallurgical coke processing
98/01473
Loana, A. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1995, 12,807-812. A burner with adjustable temperature jet for tar-containing coke gas combustion is described.
On the combustion/emissions and pulverized coal
98lo1474
of tire-derived fuel
Atal, A. and Levendis, Y. A. Chemical Physical Processes Combust. 1997, 407-410. High-volatile bituminous coal and pulverized waste tyres were studied and the flames characteristics and temperatures for the combustion behaviour and the emissions (SOz, NO,, CO, COz, and PAHs) noted. An electricallyheated drop-tube furnace was used operating at 1200” and gas residence time 0.75 s, and from fuel-lean to fuel-rich conditions.
Fuel and Energy Abstracts
March 1996
129
Combustion (burners, combustion systems)
Clrculatlng fluidited-bed combustion of Korean 98/M 466 anthracite Shun, D. et al. Hwahak Konghak, 1996, 34, (3), 321-326. (In Korean) A Korean anthracite of heating value of 4529 kcal/kg and ash content of 38% was studied in a circulating fluidized bed test unit with regard to its combustion characteristics. Feed coal was received from the mines of Samchuk province and sized to average diameter of 0.39 mm. The effect of coal feed rate on temperature profiles, the effect of excess air on combustion efficiency, sorbent effect on desulfurization, and the effect of operating variables on the emission of SO, and NO, were monitored throughout. Highest combustion efficiency of 96% was attained at the excess air ratio of 15%. Sulfur retention of 92% was achieved at a Ca/S mole ratio of 2.3. Carbon monoxide emissions varied between 210-720 ppm according to combustor temperature. Conversion of fuel nitrogen to NO, varied 4-10% by primary air ratio.
Combustion and emission characteristics of high96lO1469 moisture coal in FBC
09
COMBUSTION Burners, Combustion
Systems
Analysis for radiative heat transfer in a circulating 96lOl464 fluidized bed
Steward, F. R. et al. Proc. Inl. Conf. Fluid. Bed Cornbust., 1995, 13, (l), 507-513. For a number of different assumptions, the radiative heat transfer from the particles within a circulating fluidized bed was determined. Based on temperature profiles measured in an operating circulating fluidized bed burning coal, a procedure for predicting the radiative transfer from the solid particles to a cold wall is recommended. Approximately 59% of the total heat transfer to the wall in a circulating fluidized bed combustor is made up of the radiative transfer from the solid particles to a cold wall.
An analysis of four years of operation of the 70 MW 96fOl466 TIDD PFBC demonstration plant Mudd, M. J. and Reinhart, W. P. Proc. Inl. Conf. Fluid. Bed Cornbust., 1995, 13, (2), 925-933. Since its launch in November 1990, the 70 MW, Tidd PFBC Demonstration Plant in Brilliant, Ohio, currently the only operating PFBC Plant in the US, has now operated for four years. The plant has provided invaluable experience concerning the design and operation of the systems required to support PFBC technology and operating data necessary to commercialize PFBC combined-cycle technology at both the 200 MW thermal (70 MWe) scale, and the 800 MW thermal (350 MWe) scale. A summary is provided of the operational experience with the plant, along with key data associated with its operation.
Calculation of average volatile flame temperature of 96lOl466 oil shale particle during fluidized bed combustion Wang, G. et al. Ranshao Kexue Yu Jishu, 1995, 1, (4), 354-359. (In Chinese) It is suggested that the fluidized bed combustion of oil shale may be seriously affected by the temperature of the flame from combustion of volatile matter. The oil shale is fed to a fluidized-bed combustor causing devolatilization to occur and a diffusion flame sheet to form. The energy feedback from the flame, at a higher temperature than that of air, enhances the rate of subsequent devolatilization. An analysis solution for the average flame temperature was derived by taking the chemical reaction in the flame sheet into account, coupling heat transfer with mass transfer between the flame sheet and the particle surface and adopting the Schwab-Zeldovich transformation approach. Good agreement was discovered between the calculated results and the experimental data.
Changes of nitrogen forms during pyrolysis of coal 96lOl467 and an effect of iron loaded on coal
Zhu, Z. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1995, 12, 767-177. Both in the absence and presence of iron, the distribution and chemical changes in nitrogen forms in two demineralized Chinese coals during pyrolysis were examined. XPS analysis with curve resolution was psed to characterize nitrogen forms; the dominant nitrogen form in the demineralized coal before pyrolysis was pyrrolic. For Fe-containing coals, a significant increase in the relative amount of pyridinic nitrogen was observed after pyrolysis. Similarly, for most Fe-containing coals, there was also a conversion from quaternary to pyridinic nitrogen, although it is possible that quaternary nitrogen exists in pyrrolic form associated with oxygen functional groups before coking and is converted to true pyrrolic form. Alternatively, pyridinic nitrogen may be converted to gaseous Ncontaining molecules during pyrolysis.
Wei, X. er al. Ranshao Kexue Yu Jishu, 1997, 3, (3), 264-269. (In Chinese) This study describes the combustion and emission characteristics of high moisture coal in a fluidized bed reactor. The results indicate that the moisture and the air-fuel ratio have significant effect on the combustion and emission of high moisture coal. With increasing moisture, bed temperature and NO,, SO, emissions decrease. The air-fuel ratio has an optimal value, at which the bed temperature is maximum With increasing the ratio, NO, and SO, emissions increase. The results obtained with varying air-fuel ratio for the combustion of dry coal are similar to those for the combustion of high moisture coal.
Combustion and asification behaviors of plastics 96lo1470 injected into raceway of blast Burnace Asanuma, M. et al. Tersu to Hagane, 1997,83, (lo), 617-622. (In Japanese) The drop tube furnace, raceway hot model and scrap melting shaft furnace have been used for the investigation of the combustion and gasification behaviour of plastics. A single plastic was combusted in the drop tube furnace at around 1200°C and the burning rate of coarse plastic was found to be slower than that of pulverized coal. In the raceway hot model and scrap melting shaft furnace with the plastics injection, however, the combustion efficiency of plastics was much higher than that of pulverized coal in spite of coarse particle. Moreover, the gas composition and temperature distribution in the raceway during the plastics injection were similar to those of all coke operation. The combustion mechanism of coarse plastics was different from that of pulverized coal. These results inferred that the residence time of coarse plastics in the raceway was longer than that of pulverized coal or fine particle. The circulation model of coarse plastic particle in the raceway was newly investigated and a theoretical evaluation of the combustion efficiency of plastics was carried out. The results calculated by the circulation model agreed with those of the hot model experiments.
96lo1471 Combustion characteristics of intensively cleaned coal fractions. Effect of mineral matter
Rubiera, F. et al. DGMK Tagungsber., 1997, 9703 (Proceedings ICCS ‘97, Volume 2), 1003-1006. Intensively cleaned coal was combusted to test its effect. Samples with ash contents varying from 2 to 39% were obtained after density separation. Temperature-programmed combustion and isothermal gasification in air were used to measure the reactivities of the parent coal and the cleaned fractions. Coal and char reactivities increased with increasing ash content of the samples. Thermal analysis -mass spectrometry of the low-temperature ashes was also carried out in order to study the reactions of coal minerals under combustion conditions.
96!01472 Combustion in rotary tube furnaces: modelling, operation, and technical institution studies Stapf, D. et al. VDI-Ber., 1997, 1313, 157-162. (In German) Combustion in a rotary-tube furnace was simulated with a gas-phase model. The model took into account the pyrolysis and solids combustion processes. When solids are introduced, the deciding uncertainty factor in the model is related to the combustion kinetic data. This requires an additional model for heat and mass transfer between the combusting coke layer and the underlying solid bed.
Combustion of secondary products from metallurgical coke processing
98/01473
Loana, A. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1995, 12,807-812. A burner with adjustable temperature jet for tar-containing coke gas combustion is described.
On the combustion/emissions and pulverized coal
98lo1474
of tire-derived fuel
Atal, A. and Levendis, Y. A. Chemical Physical Processes Combust. 1997, 407-410. High-volatile bituminous coal and pulverized waste tyres were studied and the flames characteristics and temperatures for the combustion behaviour and the emissions (SOz, NO,, CO, COz, and PAHs) noted. An electricallyheated drop-tube furnace was used operating at 1200” and gas residence time 0.75 s, and from fuel-lean to fuel-rich conditions.
Fuel and Energy Abstracts
March 1996
129