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00598 Understanding slagging and fouling during pf combustion
09
Combustion (burners, combustion systems)
95loo597 Numarlcal modollng of a nucleate bolllng ?? urfaca Pasamehmetoglu, K. 0. Numerical Heat Transfer, Part A, Applications, Jun. 1994, 25, (6), 703-719. A computer program developed to analyze nucleate boiling over a heated surface is described. The model solves the three-dimensional transient conduction equation within the heater. The conduction solution is coupled with closure relationships to mimic the bubble dynamics and the associated heat transfer coefficients. Sample problems are run using a copper surface subject to partial nucleate boilink in saturated water at atmospheric pressure. The results are shown to be m good qualitative agreement with the pertinent experimental observations.
95/06604
95/00596
95Ioo505 xtractlvaly dlaCombuatlon charactarlatloa of ?? Intsgratrd coal obtalnad aftor racovary of au r clean coal and untraatrd coals by thrrmogravlmotrlc an8Pyrla In oxldlzlng atmoapherr Sharma, D. K. and Mishra, S. Fuel Sci. Technol. Ink, 1994, 12, (lo), 1303-1321. Indian coals and lignite were subjected to TGA studies in an oxidizing atmosphere (natural flow of air) as well as in a nitrogen temperature. The catalytic effect of mineral matter on the combustion of coals was more predominant in bituminous coals containing 36 to 42% volatile matter (VM) than of VM and oxygen contents of the coals. In corn arison to the original coal, the depolymerized coal and the residue obtaine B from extractive disintegration or organic solvent refining of coal under ambient pressure conditions showed higher rates of combustion at relatively lower temperatures. Several value added uses for super clean coal are suggested.
Undrrrtandlng rlagglng and fouling durlng pf combu8tlon Couch, G. IEACRI72, IEA Coal Research, Gemini House, lo-18 Putney
Hill, London SWl5, 4AA, f255.00,
Aug. 1994.
The report covers the basics of boiler design, the factors which affect it, the nature of the ash-forming materials present and their transformations in the boiler. The mechanisms of depositIon and the pro rties of the deposits formed are discussed. A number of empirical inr ices which attempt to predict the slagging or fouling propensity of a coal are described. Work is reported on advanced analytical techniques for both raw coal and for the intermediates and deposits formed. These results can be applied both to improving the capabilities of existing indices,and to computer models of the complex situation inside the boiler.
09 COMBUSTION Burners, Combustion Systems 95ltm599 Adlabatlc ravarse combustion In a packed bsd ;r;;hi, M. and Kaviany, M. Combusrion & Flame, Oct. 1994, 99, (l), Downward propagation of a combustion front in a packed bed of wood particles, with air supply from below, is examined theoretically and experimentally. Using a single-step reaction, with a kinetic model of char oxidation as the dominant mechanism, and assuming local thermal equilibrium, but allowing a local chemical noneguilibrium between the solid and gas phases, the Front speed uF, the adiabatic temperature T,, and the extend-of solid consumption are determined as functions of the entering air polevelocity. 95lOO600 Baaalln8 performance of a 200 MWt pra8aurlzad fluldlzad bad combuator Zando, M. E. and Bauer, D. A. Proc. Am. Power Co& 1994, 56, (2), 919-924. The paper describes the 70 MW, Tidd (Brilliant, Ohio) Pressurized Fluidized Bed Combustion Demonstration Plant which is a Round 1 Clean Coal Technology Project which was constructed to demonstrate the viability of PFBC combined-cycle technology for wer generation. Also given is the baseline performance of the 200 MW, I”FB combustor, including operating experience, process performance, and availability, during the first three years of the demonstration programme. 95/00601 Brief Communlcatlon. Multichannel Infrared absorption spectroscopy of solid propellant flames Modiano, S. H. and Vanderhoff, J. A. Combustion & Flame, Oct. 1994, 99, (l), 187-189. Clrculatlng fluldlzad bad ataam generator for coal 95lOO602 and low-grade fuels Stonebridge, R. and Gorman, R. B. Report EUR.15025, Comm. Eur.
Communifies, 1994, 49 pp.
The objective of this ro’ect was to demonstrate a high efficiency, cost effective circulating RIII.d*lzed bed steam generator for industrial steam users requiring between 30,000-60,000 kg/h of steam and capable of firing coal and low grade fuel. The operation of the steam generator was also to prove current and future emissions control for this size of boiler plant could be achieved with minimal plant equipment or cost. 95/00603
Comblnad cycle wlth pressurized fluldlzad bad combustion iaid, P. Collect Notes Inrernes Dir. Erud. Rech., Prod. Energy. (Hydraul. Therm. Nuc1.k 94NBOOO87,1994, 41 oo.
A review of’pressurized fluidized he’d’combustin of coal and its many variations, especially for power generation, including ongoing developments to improve availability, further reductions in emissions, and increased cycle and partial load efficiency.
Combuatlon charactorlatlca In coal-flrad vortex flu-
Idlzad bade JininnfBe)er aL,
Gongcheng Rewuli Xuebao, 1994, 15, (l), 104-107. (In
Discusses vortexing fluidized-bed combustion (VFBC) which is a new FBC technique. In order to obtain the key technique of VFBC, the mechanistic and demonstrative investigations of combustion were made in a cold model and a hot test facility, respectively. An investigation was made of the effects of vortex performance parameter-swirl number on aerodynamic characteristics and temperature distribution in freeboard, combustion efficiency and pollution emission.
Combuatlon klnstlca of coke pattlcl88 In a fluldlzad 95/00606 bad reactor Fuertes, A. B. er al., Fuel Process. Technol., 1994, 38, (3), 193-210. Combustion studies with a metallurgical coke were carried out in batch experiments in an electric heated fluidized-bed reactor in air at 750-950’ with coke particle diameters of 0.675-3.500 mm. A methodology for estimating the kinetic parameters of semicoke combustion was developed. From the response of gas outlet concentrations to the batch amount, a parameter to estimate the mean oxygen concentration in the bed was deduced. The overall rate constants at each burnoff stage were also obtained. 95/00507 The comburtlon raactlvlty and phy8lochamlcal propartlaa of rarldual carbon from pulvarlzad coal flrad boiler8 Hurl, R. H. et al., Prepr. Pap.-Am. Chem. Sot., Div. Fuel Chem., 1994, 39, (l), 183-187. Discusses the combustion reactivities and physiochemical properties for a suite of residual carbon samoles from commercial boilers. The results are compared to identical measuiements made on chars in the early-to-intermediate stage of combustion, generated under controlled conditions in the laboratoj. 95/00506 Conceptual darlgn and aconomlca of coal and gra co-flrsd PFBC plants Horazak, D. A. et al., Proc. Am. Power Conf, 1994, 56, (2). 925-929. The namer describes the concentual desien and oueration. including an econom’ic analysis for an intermidiate sta& pressurized fluibized-bed-wal combustion unit as a logical alternative to a second-generation PFBC plant, which is perceived has having increased technology risk related to pressurized carbonizer systems. 95/oo509 Contribution to the study of carbon dsporltlon In coke oven8 Krebs, V. et al., Fuel, Dec. 1994, 73, (12), 1904-1910. The formation of carbon deposits from coal pyrolysis in a two-stage reactor has been studied for several cracking temperatures from 850 to 1000°C. The weight of the carbon deposit was monitored continuously during pyrolysis by a thermogravimetrlc balance. Four successive periods of deposition were distinguished. The control of NO, by bafflalnducsd flow-staging 95/00510 ~~I_~$II, J. B. et al., J. Instilute of Energy, Sep. 1994, 67, (472), The current Hamworthy low-NO, 3-100 MW dual-fuel register burner design incorporates bluff baffles to induce a circumferentially staged airflow. It is coupled with a staged atomiser producing a unique flame structure, which demonstrates a Kigh degree o? flow staging and an effective means of controlling the formation of NO. This paper presents the results of comprehensive RF0 firing trials, isothermal Lo-mb&tion air mapping, fuel jet trajectory-visualisation trials and flame-temperature profiling, from which the effect of NO_-controllinn aeometrv on the burner emissions and flame structure were de&cd. Tbege?esults 6re related to the environmental factors created within the flame and believed to influence the mechanisms of NO formation. Finally the implications of the results of the trials and analysis of the results on burner design are discussed.
Fuel and Energy Abstracts January 1995
35
Combustion (burners, combustion systems)
95loo597 Numarlcal modollng of a nucleate bolllng ?? urfaca Pasamehmetoglu, K. 0. Numerical Heat Transfer, Part A, Applications, Jun. 1994, 25, (6), 703-719. A computer program developed to analyze nucleate boiling over a heated surface is described. The model solves the three-dimensional transient conduction equation within the heater. The conduction solution is coupled with closure relationships to mimic the bubble dynamics and the associated heat transfer coefficients. Sample problems are run using a copper surface subject to partial nucleate boilink in saturated water at atmospheric pressure. The results are shown to be m good qualitative agreement with the pertinent experimental observations.
95/06604
95/00596
95Ioo505 xtractlvaly dlaCombuatlon charactarlatloa of ?? Intsgratrd coal obtalnad aftor racovary of au r clean coal and untraatrd coals by thrrmogravlmotrlc an8Pyrla In oxldlzlng atmoapherr Sharma, D. K. and Mishra, S. Fuel Sci. Technol. Ink, 1994, 12, (lo), 1303-1321. Indian coals and lignite were subjected to TGA studies in an oxidizing atmosphere (natural flow of air) as well as in a nitrogen temperature. The catalytic effect of mineral matter on the combustion of coals was more predominant in bituminous coals containing 36 to 42% volatile matter (VM) than of VM and oxygen contents of the coals. In corn arison to the original coal, the depolymerized coal and the residue obtaine B from extractive disintegration or organic solvent refining of coal under ambient pressure conditions showed higher rates of combustion at relatively lower temperatures. Several value added uses for super clean coal are suggested.
Undrrrtandlng rlagglng and fouling durlng pf combu8tlon Couch, G. IEACRI72, IEA Coal Research, Gemini House, lo-18 Putney
Hill, London SWl5, 4AA, f255.00,
Aug. 1994.
The report covers the basics of boiler design, the factors which affect it, the nature of the ash-forming materials present and their transformations in the boiler. The mechanisms of depositIon and the pro rties of the deposits formed are discussed. A number of empirical inr ices which attempt to predict the slagging or fouling propensity of a coal are described. Work is reported on advanced analytical techniques for both raw coal and for the intermediates and deposits formed. These results can be applied both to improving the capabilities of existing indices,and to computer models of the complex situation inside the boiler.
09 COMBUSTION Burners, Combustion Systems 95ltm599 Adlabatlc ravarse combustion In a packed bsd ;r;;hi, M. and Kaviany, M. Combusrion & Flame, Oct. 1994, 99, (l), Downward propagation of a combustion front in a packed bed of wood particles, with air supply from below, is examined theoretically and experimentally. Using a single-step reaction, with a kinetic model of char oxidation as the dominant mechanism, and assuming local thermal equilibrium, but allowing a local chemical noneguilibrium between the solid and gas phases, the Front speed uF, the adiabatic temperature T,, and the extend-of solid consumption are determined as functions of the entering air polevelocity. 95lOO600 Baaalln8 performance of a 200 MWt pra8aurlzad fluldlzad bad combuator Zando, M. E. and Bauer, D. A. Proc. Am. Power Co& 1994, 56, (2), 919-924. The paper describes the 70 MW, Tidd (Brilliant, Ohio) Pressurized Fluidized Bed Combustion Demonstration Plant which is a Round 1 Clean Coal Technology Project which was constructed to demonstrate the viability of PFBC combined-cycle technology for wer generation. Also given is the baseline performance of the 200 MW, I”FB combustor, including operating experience, process performance, and availability, during the first three years of the demonstration programme. 95/00601 Brief Communlcatlon. Multichannel Infrared absorption spectroscopy of solid propellant flames Modiano, S. H. and Vanderhoff, J. A. Combustion & Flame, Oct. 1994, 99, (l), 187-189. Clrculatlng fluldlzad bad ataam generator for coal 95lOO602 and low-grade fuels Stonebridge, R. and Gorman, R. B. Report EUR.15025, Comm. Eur.
Communifies, 1994, 49 pp.
The objective of this ro’ect was to demonstrate a high efficiency, cost effective circulating RIII.d*lzed bed steam generator for industrial steam users requiring between 30,000-60,000 kg/h of steam and capable of firing coal and low grade fuel. The operation of the steam generator was also to prove current and future emissions control for this size of boiler plant could be achieved with minimal plant equipment or cost. 95/00603
Comblnad cycle wlth pressurized fluldlzad bad combustion iaid, P. Collect Notes Inrernes Dir. Erud. Rech., Prod. Energy. (Hydraul. Therm. Nuc1.k 94NBOOO87,1994, 41 oo.
A review of’pressurized fluidized he’d’combustin of coal and its many variations, especially for power generation, including ongoing developments to improve availability, further reductions in emissions, and increased cycle and partial load efficiency.
Combuatlon charactorlatlca In coal-flrad vortex flu-
Idlzad bade JininnfBe)er aL,
Gongcheng Rewuli Xuebao, 1994, 15, (l), 104-107. (In
Discusses vortexing fluidized-bed combustion (VFBC) which is a new FBC technique. In order to obtain the key technique of VFBC, the mechanistic and demonstrative investigations of combustion were made in a cold model and a hot test facility, respectively. An investigation was made of the effects of vortex performance parameter-swirl number on aerodynamic characteristics and temperature distribution in freeboard, combustion efficiency and pollution emission.
Combuatlon klnstlca of coke pattlcl88 In a fluldlzad 95/00606 bad reactor Fuertes, A. B. er al., Fuel Process. Technol., 1994, 38, (3), 193-210. Combustion studies with a metallurgical coke were carried out in batch experiments in an electric heated fluidized-bed reactor in air at 750-950’ with coke particle diameters of 0.675-3.500 mm. A methodology for estimating the kinetic parameters of semicoke combustion was developed. From the response of gas outlet concentrations to the batch amount, a parameter to estimate the mean oxygen concentration in the bed was deduced. The overall rate constants at each burnoff stage were also obtained. 95/00507 The comburtlon raactlvlty and phy8lochamlcal propartlaa of rarldual carbon from pulvarlzad coal flrad boiler8 Hurl, R. H. et al., Prepr. Pap.-Am. Chem. Sot., Div. Fuel Chem., 1994, 39, (l), 183-187. Discusses the combustion reactivities and physiochemical properties for a suite of residual carbon samoles from commercial boilers. The results are compared to identical measuiements made on chars in the early-to-intermediate stage of combustion, generated under controlled conditions in the laboratoj. 95/00506 Conceptual darlgn and aconomlca of coal and gra co-flrsd PFBC plants Horazak, D. A. et al., Proc. Am. Power Conf, 1994, 56, (2). 925-929. The namer describes the concentual desien and oueration. including an econom’ic analysis for an intermidiate sta& pressurized fluibized-bed-wal combustion unit as a logical alternative to a second-generation PFBC plant, which is perceived has having increased technology risk related to pressurized carbonizer systems. 95/oo509 Contribution to the study of carbon dsporltlon In coke oven8 Krebs, V. et al., Fuel, Dec. 1994, 73, (12), 1904-1910. The formation of carbon deposits from coal pyrolysis in a two-stage reactor has been studied for several cracking temperatures from 850 to 1000°C. The weight of the carbon deposit was monitored continuously during pyrolysis by a thermogravimetrlc balance. Four successive periods of deposition were distinguished. The control of NO, by bafflalnducsd flow-staging 95/00510 ~~I_~$II, J. B. et al., J. Instilute of Energy, Sep. 1994, 67, (472), The current Hamworthy low-NO, 3-100 MW dual-fuel register burner design incorporates bluff baffles to induce a circumferentially staged airflow. It is coupled with a staged atomiser producing a unique flame structure, which demonstrates a Kigh degree o? flow staging and an effective means of controlling the formation of NO. This paper presents the results of comprehensive RF0 firing trials, isothermal Lo-mb&tion air mapping, fuel jet trajectory-visualisation trials and flame-temperature profiling, from which the effect of NO_-controllinn aeometrv on the burner emissions and flame structure were de&cd. Tbege?esults 6re related to the environmental factors created within the flame and believed to influence the mechanisms of NO formation. Finally the implications of the results of the trials and analysis of the results on burner design are discussed.
Fuel and Energy Abstracts January 1995
35