04987 Development of a novel peak-seeker control system suitable for waste incinerators

09 95lo4977 Combustlon of cyllndrlcal and sphrrlcal random clusters of char/carbon oartlclea Elperin. T. and Kr&witov, b. Proc. 10th Int. Hear Transfer CW$, Inst. Chem. Eng., Rugby, UK 1994, 2, 31-36. The interaction between burning char/carbon particles of different sizes is analyzed in a quasi-steady approximation. The method of solution is based on the expansion into irreducible multipoles developed in an earlier paper. It is assumed that the chemical reaction which occurs on the surface of the particles is of first order. The developed method is applied for the analysis of burning rate of spherical and cylindrical clouds of particles. Tbe results are presented in terms of correction factor defined as a ratio of a burning rate of a particle located inside a cloud to a single particle burning rate. 95104978 Combuatlon of low rade anthracite under varloua condltlona of Introduction o? drvBna aaent Into the furnace Shnitser, 1. N. Te loenergerika @40&o& i994, (8), 13-17. (In Russian) A steam boiler wi*ig a 200 MW turbine is fiied with pulverized anthracite containing U-2546 drying akent under a range of o rating conditions. Optimum combustion conditions are attained when aee combustion air is supplied through the burners. However, this operating mode increases NO, emissions. 95tO4979 Combuatlon of low-grade coals wlth prellmlnary thermal preparatlon In vortlcal precombustlon chamber Teploenergetika (Moscow), 1994, (9), 42-48. (In Russian) Pulverized anthracite breeze is heated with natural gas combustion gases to 940-1080 K prior to injection into a boiler, which increases the anthracite reactivity and improves its ignition. A pulverized coal burner with a thermal stabilixer was constructed based on these results. 95104980 Combustlon of methane and ethane wlth CO replaclng N, as a dlluent. Modelllng of combined effects of detalled chemical klnetlca snd thermal propertles on the early stages of combustion Yossefi, D. et aL, Fuel, Jul. 1995, 74, (7), 1061-1071. Simulation of methane combustion are develo d for a synthetic atmosuent with carbon dioxide. here system where nitrogen is replaced as dip” g pecial attention is given to the role of the detailed chemistry, using a scheme containing approximately 100 separate reactions. The sensitivity of the results to the major reactions is analysed, and the approach to eoudibrium is considered. -Examination of a &t of model r&ems shows that where there is a large initial concentration of carbon gioxide, the chemical effects are very important. The results for constant-pressure combustion coincide with conventional expectations, whereas those for a constant-volume system initiated by isotropic auto-ignition are very much counter to intuition. 95/04981 A comparlaon of the pyrolyals of coal In wlre-mesh and entralned-flow reactors Hidmarsh, C. J. ef al., Fuel, Aug. 1995, 74, (8), 1185-1190. The properties of chars derived from coals of a wide range of rank produced in wire-mesh (WMR) and entrained flow (EFR) reactors were compared. The WMR was operated at atmospheric pressure of helium or nitrogen with heating rates of Z-5000 KS”, temperatures up to 1773 K and residence time of Z-30 s. The EFR was operated at 1273 K with a residence time of 1 s in nitrogen at atmospheric pressure. Tbe yield of volatile matter fom the EFR was consistently lower than that from the WMR; accordingly, the EFR chars were of significantly higher residual volatile matter than the corresponding WMR chars. Differences in yields and char reactivities were observed between yrolysis in helium and nitrogen. The extent of secondary reactions an s experimental flow arrangements accounted for the remaining difference. 95104982 Control of gravlty charging of coke ovens W;c$. et al., Rev. MetallICah lnfl Tech., 1994,91, (11). 1635-1644. (In The grivity fillin of a coke oven was independent on the rheological characteristics oft %e coal blend, especially the an e of repose and the coal compaction behaviour. The variation of angle o!l repose. of the coal was studled by varying the type of coal, moisture content, size distribution, and flow rate in a l:lO-scale cold model of the actual coke oven. Although moisture had a large effect on the angle of repose, the influence of coal type is not to be neglected. 95104983 Converslon of 40 metric tons per hour t/h) mw br?wn coal bollers to powdered llgnlte and fuel oil andI or naturangas Rau, F. and Stahn, C. D. Energieanwend, Energ.-Umweltted, 1994.43, (12), 480-482. (In German) Retrofitting of the brown coal-fired boiler to combined powdered lignitefuel oil f~mg includes vibrating-grate firing, coal desulphurixation with a dry additive, dust removal in the combustion chamber by gravity or centrifugal separation of, and the inwrporatin of ash silos. Converalon of BKZ210-140 boller In Chelyablnek 95lQ4984 heat and power plant-2 to natural gas tlrlng wlth separaie burnera and alr aupply ducts Osintsev, V. V. et a&, EL&r. Stn., 1994, Q, 8-13. (In Russian)

Combustion (bumem, comb&on

systems)

95/04985 clans separators performance under hlgh The temoeraturs In PF2 C unlt Shi,‘M. et al, Heat Recovery Syst. CHP, 1995, 15. (Z), 191-198. Describes the operation of a high temperature gas cleanup system, which consists of three cyclone separators in series, and has operated satisfactorily through 500 h in a 1 Mwt pressurized fluid&d bed combustor pilot test unit. The total collection efficiency of this system was 99-99.3%. 95lO4988 Dealgn conaldsratlona for PFBC gas expander Pengfei, L. Heat Recovery Syst. CHP, 1995, 15, (Z), 179-190. Describes the design of a pressurixed fluidize.d bed combustion (PFBC) gas expander which is established on the basis of experience accumulated in the design of fluidized-bed catalytic crackers flue gas expanders. 95/04987 Development of a novel peak-reeker control aystern sultabls for waste lnclneratora Vara-Munox, M. C. et al., J. Institute of Energy, Jun. 1995, (475), 85-92. Gas-sampling systems have shown an inability to respond to the rapid changes in conditions normally experienced in solid-waste incinerators, and this has led to control problems. Even in large municipal incinerators, oxygen deviations take lace in timescales comptible to the gas-sampling has the lag. The spectroscopy- %ased system-the peak-seekerdcscnbed potential to solve these problems. The research, design and development of a computerised peak-seeker control system that may be applied to the secondary zone of a waste incinerator is also described. Tests made on a laboratory-based oil furnace include multisine system characterisation and the effect of fuel flow on the control point. 95104988 Development of hlghly ?? nvlronment-friendly fluldlzed bed combustion technology Kamata, T. et al,, Sekiran Riyo Gijutsu Kaigi Koenshu, 1994,4,41-50. (In Japanese) Discusses the development of a low emission fluid&d bed coal combustion process. THe characteristics of the process are low-temperature combustion to suppress NO, formation, high-temperature free board to remote F$O and CO decomposmon, large grain desulphurizing agent, an1 a auf& clent residence time for free board gas by controlling recycled ash. 9SlQ4989 Development of presaurlzed Internally clrculatlng fluldlzed bed combustion technology Kamata, T. et aL, Sekitan Riyo Gijutsu Kaigi Koenshu, 1994,4,61-71. (In Japanese) Describes the advantages of a circulating type boiler and bubbling type boiler which were combined to device a pressurized internally circulating fluidized bed combustor, which is load controllable, rapid load response, and low emission. 95104990 A drop tube furnace study of coal combustion and unburned carbon content uslng optlcal techniques Card, J. B. and Jones, A. R. Combustion & Flame, Jun. 1995, 101, (4), 539.547. The combustion of pulverized coal in a drop tube furnace has been studied optically. The coal passes through an excess air flame to ensure ignition and then burns as it passes down a segmented ceramic tube electrically heated to llOO°C. The method permits the optical measurement of particle size distribution as a function of residence time. The results of this demonstrate the relative reactivity of the coals used and also indicate that fragmentation may occur. SAmples of the particles rue taken as each furnace stage for Carbon-Hydrogen-Nitrogen analysis. 95/04991 Dynamic modellng Korving,A. Coal Sci. TechnoL, 1995, 22, 353-385. The paper describes the modelling of the dynamic behaviour of coal-fued bubbling fluidized-bed boilers under operating conditions. Topics discussed: fluidixed-bed modelling (reference model, semicoke mass balance, heat transfer coefficient, energy balance, fluidixation and gas mixing, and Fcerta$ities), modelling of 8. mul!ic+l atmosphe@c bed, later+ mix@, $~;;s~on, freeboard model, tietlzahon and solution method, suuulation

WO4992 Effect of nonunlty Lewls number on premlxrd flame propaqatlon through lsotroplc turbulence Dandekar, k &d Collins,LLR Co&u&on & Flame, Jun. 19!35,101, (4X 428-440. Direct numerical simulations of a passive premixed flame surface propagating through stationary isotropic turbulence have been performed in three dimensions on a 96’mesh with a particular emphasis on characterizing the effects of Lewis number on the rate of propagation of the flame surface and flame surface topology. The simulations were based on the flame sheet assumption that unplies that the time scale for chemcial reaction is short as compared with the time scales for the turbulent fluctuations (so-called flamilet regime). In this limit, the flame surface can be represerited by a field equation which accounts for local advection of the reaction front due to instantaneous velocity fluctuations and propagation due to reaction.

Fuel and Energy Abstracts Beptembsr 1995

852