09 Combustion (burners, combustion systems)

96/02922 Retrofitting of Jaenschwalde power station with3000 MW of electric power based on nitrogen oxide free com­bustion technology with extensive adherence to the originalplant configurationPeter, R. et al., VGBKraftwerkstech., 1995, 75, (9), 805-813. (In German)The steam boiler at the lignite-fired Jaenschwalde power plant in EastGermanywas converted in 1991 and recommissioned.The foundationfor asuccessful trial was established by comprehensive measures such as air andfuel gradation, air volume decrease, fuel concentration, and vapour separa­tion. Also a comprehensive boiler and combustion equipment refurbish­ment programme was undertaken leading to good operating results.

96/02923 Weld repair of steam drum downcomer nozzlecracking in coal-fired power plantAllen, D. 1. Weld. Met. Fabr., 1995, 63, (6), 225-228.Describes the weld repair recently carried out by PowerGen to a crackedsteam drum downcomer nozzle weld in a coal-fired500MW unit at CottamPower Station. It illustrates how a major on-site repair may be imple­mented, including the application of specialized weld repair techniques.

09 COMBUSTION

Burners, Combustion Systems

96/02924 Analyzer of unburned coal-dust fuel In the boilerunits of thermal power plantsTarasevich, V. N. Elektr. Stn., 1995, (8), 6-13. (In French)The author describes an analyzer for the determination of carbon in fly ash.The method is based on gasification of the ash carbon, followed by thermo­chemical measurement of CO concentration in gasification products.

96/02925 Appliance ventilation ducts for room-sealedappliancesBaumann, P. et al., Gaz d'aujourd'hui, Jan. 1996, 120, (I), 7-14. (InFrench)The penetration of natural gas into the multi-family market has alwaysbeen a preoccupation for Gaz de France. As far as independant heating isconcerned, professions involved in the building industry are wellacquainted with the advantages of room-sealed appliances. Balanced fluedappliances with horizontal flue terminals have been on the market forseveral years now, and recently, balanced flued appliances with flue termi­nal projecting above the roof have also appeared on the market. All thatwas missing from this range was an appliance ventilation duct. The prob­lem has now been solved. This duct is now on the market. The article, aftera general introduction to this new system, presents the technical character­istics of three products currently available in France.

96/02926 Assessment of turbulent combustion submodelsusing linear eddy modelDesjardin, P. E. and Frankel, S. H. Combustion & Flame, Feb. 1996, 104,(3), 343-357.Linear eddy model simulations are conducted in order to study turbulence­chemistry interactions in a homogeneous, incompressible,stationary turbu­lent flow with non-premixed reactants. The chemical kinetics model usedin this work involves single- and multi-step, reversible and irreversibleisothermal reactions. The simulation results are employed to investigate theflame structure and statistics and comparisons are made to several otherturbulent combustion models.

96/02927 Asymptotic and numerical study of diffusionflames with variable Lewis number and finite rate chemistryCuenot, B. and Poinsot, T. Combustion & Flame, Jan. 1996, 104, (1),111-137.The authors used an an asymptotic method to derive analytical expressionsfor the profiles of all thermodynamic and chemical quantities of diffusionflame with variable density, nonuniform Lewis number and finite ratechemistry, and for different configurations (unsteady unstrained, steadystrained and unsteady strained flames). The accuracy of the results arechecked using numerical simulations with the same chemical and transportmodels. The results are then used to quantify the effects of finite ratechemistry and different Lewis numbers on the flame structure.

96/02928 Burning velocities, Markstein lengths, and flamequenching for spherical methane-aIr flames: A computationalstudyBradley, D. et al., Combustion & Flame, Jan. 1996, 104, (1), 176-198.Computations are for three modes of spherical laminar flame propagation:explosion, implosion and stationary. The reduced kinetic C" scheme ofMauss and Peters is employed for a range of equivalence ratios underatmospheric conditions, with flame propagation at constant pressure. Savefor the richest mixtures, the scheme is fully adequate for present purposes.Two burning velocities are computed, one based on the rate of disapper­ance of unburned gas, the other on the rate of appearance of burned gas.

204 Fuel and Energy Abstracts May 1996

96/02929 The characteristics of pulverized coal combustionin 02/C02 mixtures for CO2 recoveryKimura, N. et al., Energy Converso Mgmt., Juri-Sep. 1995, 36, (6),805-808.O/COz blown combustion is a promising technique in the technology ofrecovering COz from flue gases generated by coal-fired power plants. Thefuel in such a system is burned in an Oz/COz mixture instead of air, raisingthe COz concentration in the flue gas to about 95%. In order to determinethe characteristics of pulverized coal combustion in the O/COz mixture,the authors conducted a benchscale test using a 1.2-MWt tunnel furnacewith a coal feed rate of 150 kg/h. This project is proceeding as part of anational project and financial supported by New Energy and IndustrialTechnology Development Organization (NEDP), Japan.

96/02930 Chemical kinetic modeling of N2 formation anddecomposition during coal combustionYuan, J. and Feng, B. Huazhong Ligong Daxue Xuebao, 1995, 23, (4),114-119. (In Chinese)Presents a chemical kinetic modelling of NzO formation and decomposi­tion during the combustion of a single coal particle and volatiles in thefreeboard of a fluidized bed combustor.

96/02931 Chemical structures of fuel-rich flames of trans-C2H2CI2/CHJAr/0 2 mixturesCastaldi, M. 1. and Senkan, S. M. Combustion & Flame, Jan. 1996, 104,(1),41-50.Temperature and species concentration profiles were obtained for atmos­pheric-pressure, premixed, laminar, flat flames of trans-CzHzClz/CH4 mix­tures under fuel-rich conditions at several Cl/H ratios.

96/02932 Circulating fluld-bed reactor for coal pyrolysisSciazko, M. and Zielinski, H. Chem. Eng. Technol., 1995, 18, (5),343-348.Describes a high-temperaturecoal pyrolysis reactor which has been devel­oped and demonstrated at a scale of 8 tons/h. The process, which wasconsidered a partial coal gasification system, was carried out in a circulat­ing fluidized bed at 850-950° and integrated into a demonstration plant formanufacture of briquetted smokeless fuel.

96/02933 Coal combustion under conditions of blast furnaceinjectionCrelling, J. C. Proc. lronmaking Conf., 1995, 73-79.Based on computer modelling results, lower-rank bituminous coal (includ­ing coal from the Illinois Basin) compare well in their injection propertieswith a variety of other bituminous coals, although the replacement ratioimproves with increasing rank. Based on petrography analyses of materialcollected from an active blast furnace, it is clear that a coal-derivedsemicoke actually enters the raceway of the blast furnace. Results indicatethat the semicokes from the lower-rank coals should have a superiorburnout rate in the tuyere and should survive in the raceway environmentfor a shorter time.

96/02934 Coal particle surface characteristics and the sur-face smoothness factor in theory of combustionGu, F. et al., Yingyong Kexue Xuebao, 1995, 13, (2), 127-135. (InChinese)Discusses the relationship between coal combustion and the particle sur­face smoothness factor which was established by energy pattern analysis.A measurement system consisting of an ESM and an image computer wasdeveloped and used.

96/02935 Coke oven gas combustion systemsCheng, C. L. Nengyuan Jikan, 1995,25, (3), 181-188. (In Chinese)Discusses how staged air concept is used to design a coke oven gas com­bustor with efficient control of NO, formation.

96/02936 Combined combustion of biomass, municipal sew­age sludge and coal in an atmospheric fluidized bed installationVan Doorn, 1. et al., ECN-C Report ECN-C-95-096, 1995, 34 pp.The cofiring of biomass or sewage sludge with coal in a fluidized-bedinstallation influences the combustion behaviour and the flue gas emis­sions. In the case of coal/wood co-combustion the concentrates of NO"S02 and CO in the flue gas were lower compared with coal-firing. Nooperational problems were observed with co-firing wood and coal. In thecase of straw and sewage sludge agglomeration of the bed materialoccurred; adaptations of the combustion conditions are necessary for com­mercial application.

96/02937 Combustion mechanism of pulverized coal injectedinto blast furnace and its simulationSato, M. et al., Rev. Metall./Cah. In! Tech., 1995, 92, (3), 343-349.In order to understand the behaviour of pulverized coal injected into blastfurnaces, direct observation of the combustion using high-speed camerawas used. It was found that the combustion flame of pulverized coat wasnot uniform across the cross-section in blowpipe and tuyere. It was foundthat the flow pattern of pulverized coal particles governed by injectionlance arrangement had a significant effect on combustibility.