06321 Ash vaporization in circulating fluidized bed coal combustion

06321 Ash vaporization in circulating fluidized bed coal combustion

09 Influence of ash depoalt chemistry and structure 96106311 on phy8lcal and tmnaport properties Baxter, L. L. Prepr. Pap.-Am. Chem. Sot., Div. Fuel C...

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09 Influence of ash depoalt chemistry and structure 96106311 on phy8lcal and tmnaport properties Baxter, L. L. Prepr. Pap.-Am. Chem. Sot., Div. Fuel Chem., 1996, 41, (2), 657-661. Boiler ash deposits generated during combustion of coal, biomass, black liquor, and energetic materials affect both the net plant efficiency and operating strategy of essentially all boilers. Such deposits decrease convective and radiative heat exchange with boiler heat transfer surfaces. In many cases, even a small amount of ash on a surface decreases local heat transfer rates by factors of three or more. The report relates the chemical and microstructural properties of ash deposits to their physical and transport properties. 96lO6312 Meaaurlng the vlscoua flow of molten coal ash Stanmore, B. R. and Budd, S. Fuel, Oct. 1996, 75, (12), 1476-1479. The condition which determines whether ash will caisi fouling on heat transfer surfaces in p.c.-fired boilers is that the viscosity must lie between 0.1 and 10 MPa s. Ash under these conditions is stiff, exists in two phase and exhibits a yield stress. A new ty e of rheometer consisting of a stanIfled to act in the squeeze film mode dard thermomechanical analyzer mo b!* is proposed to measure ash fluidity. Flat pellets of sample heated to operating temperature under a stream of nitrogen were subjected to a constant compressive load. Analysis of the sample thickness at any point and its rate of deformation provided the Bingham viscosity and yield stress. An ASTM lass at 75O’Cgave a viscosity near the standard value, while a brown coal a y ash exhibited a yield stress of approximately 1 kPa at 1190°C. 96106313 A 1000 MW coal flred supercrltlcal slldlng pressure operation holler wlth vertical furnace waterwall Kaneko, S. et al., Mitsubishi Juka Giho, 1996, 33, (l), 6-9. (In Japanese) Describes the design features and trial operation results of the first 1000 MW coal fired supercritical sliding pressure operation boiler with vertical furnace wall. 96106314 Redealgn of DKVr and KE hollers for combustion of low-arade fuels Matsnev, V. V. et al., Energetik, 1995, (ll), 14-15. (In Russian) Describes the modifications of DKVr and KE fluidized-bed boilers for operation on brown coal, oil shale and wood waste.

09 COMBUSTION Burners,

Combustion

Systems

96/06315 Addltlve for decrease of alr pollution during combustion of brown coal Harms, U. et al., (Assigned to) Lausitzer, Braunkohle A.-G (LAUBAG), GER. Par. DE.4,421,313,

Dec. 1995.

96106316 Advanced burner design for pulverized coal combustlon In utlllty bollers Van de Kamp, W. L. er al., Coal Sci. Tech&., 1995, 24, 811-814. An overivew of a limited number of selected topics of the IEA Coal Cornbustion Sciences oro~amme Part 3 which was executed bv the Intemationai Flame Res&r& foundation in Ijmuiden. The subjects’are related to low NO, combustion by burner fuel staging and the combustion of pulverized coal with turbine exhaust gas. 96106317 Advanced technolo les for coal uallty evaluation for pulverized coal combustion. ‘b redlctlon ofR 0, emissions Kambara, S. Boira Kenkyu, 1996, (275), 25-29. (In Japanese) The paper discusses the NO formation mechanisms of various coals during combustion to predict their NO, emission. In low C% coals (young coals), amine type and pyridine type nitrogen were abundant, and in high C% coal pyrmle type nitrogen was abundant.

Combustion (burners, combustion systems)

Ash fusion tempemtures and the tmnsformatlons 96lO6320 of coal ash partlclea to slag Gupta, S. et al., Prepr. Pap.-Am. Chem. Sot., Div. Fuel Chem., 1996,41, (2‘1,647-651. se paper discusses a mechanistic study in which coal ash is heated with its shrinkage measured continuously up to a temperature of 1600”. The temperatures corres onding to the iapid rate of shrinkage are shown to correspond to the Pormation of eutectics identified on phase diagrams. Samples were heated to these temperatures, cooled rapidly and examined with an SEM to identify the associated chemical and physical changes. Ash vaporlzatlon In circulating fluldized bed coal 96lO6321 combustion Lind, T. et al., Aerosol Sci. Technol., 1996, 24, (3), 135-150. Discusses the vaporization of ash forming constituents in circulating fluidized bed combustion (CFBCI in a full-scale 80 MW, unit. Ash vaoorization in CFBC was studied b; measuring the flv ash a&osols in a f&-scale boiler upstream of the elect;ostaiic prgipitato; at the flue gas temperature of 125°C. The fuel was a Venezuelan bituminous coal, and a limestone sorbent was used during the measurements. 96106322 Carbonization of mixtures of coal tar pitch and orsohlte FeCI. comoounds: A Mossbauer studv EeGn, D. et al, Carbon, 1996, 34, (3), 331-337. Mixtures of coal tar pitch and first-stage FeC$-graphite intercalation compounds (GIG) have been synthesized with chfferent GIC concentrations, then pyrolysed at different final temperatures and at several heating rates. Mossbauer spectroscopy has been used to characterize the iron states after these thermal treatments. 96106323 Characteristics of gas evolution durlng coal carbonlzatlon Matsuoka, K. et al., Tetsu to Hagane, 1996, 82, (5), 383-387. (In Japanese) Changes’in mass with time due to gas evolution during carbonization were observed for particles and a cylindrical pellet of various coals heated respectively iti a thermogravimetric balaice and a microautoclave. The experiments were carried out at heating rate from 1 to 50 Wmin, soaking temperature from 673 to 823 K and 0.1 and 1.0 MPa N. The effects of these operating variables on the gas evolution characteristics were experimental examined. 96106324 Co-combustion and fluldlzed-bed lncinemtlon of cellulose pellets Saxena, S. c. and Dewan, S. S. Energy, Oct. 1996, 21, (lo), 889-897. Co-combustion of cellulose pellets with propane gas as an auxiliary fuel is investigated in the University of Illinois fluidized-bed incinerator. The incineration phenomenon is -examined as a function of the operating parameters which are the pellet and propane-gas feed rates, bed temperature, superficial gas fluidizing velocity, and fractional excess air. Carbon and thermal combustion efficiences are computed from the relations which have been develo ed on the basis of carbon and thermal energy balances together with the z nowledge of propane and cellulose pellet feed rates and the composition of the flue gas. Emission of CO for optimum combustion conditions is always found to be well within the limit set by the Illinois Environmental Protection Agency. Optimum operating conditions are established for the incineration process. 96106325 Coal ash deposit and new Indexes Zhou, Y. et al., HuazhonnI Linonn _ _ Darue Xuebao, 1995, 23, (8), 23-27. (In Chinese) Based on the mechanisms of evaporation, condensation and deposit of minerals during coal combustion, the deposit tendency including that of slagging and fouling of various kinds of coal was theoretically and experimentally studied. 96106326 Coal firing device Sonoda, K. et al., (Assigned to) Mitsubishi Jukogyo Kabushiki Kaisha,

Japan, EUR. Par. EP.699,734,

96106316 Apparatus for carbonlzatlon of wood wastes for manufacture of carbonaceous materlals Wakasugi, S. (Assigned to) Wakasugi Seiko, Japan, JAP. Pat.

JP. 08,20,779, Jan 1996. The apparatus consists of a horizontal cylindrical body with a rotary screw

to convey the passage of wood wastes, and a means ior indirectly -heating from outside the cylindrical body for carbonization without direct burning _ of carbonaceous niaterials. 96106319 Artlflclal neural network lmplementatlon of chemlstry with pdf simulation of H&O flames Christo, F. C. er al., Combusrion & Plame, Sep. 1996, 106, (4), 406-427. A novel approach using artificial neural networks for re resenting chemical reactions is developed and successfully implemente B with a modelled velocity-scaler joint pdf transport equation for HJCO turbulent jet diffusion flames. The chemical kinetics are represented using a three-step reduced mechanism, and the transport equation is solved by a Monte Carlo method.

Mar. 1996.

Describes an improvement of a coal firing device applied to entrained-bed coal gasifiers, and boilers for power generation. 96106327 Coal hydromethanolysls with coke-oven gas. 3. Influence of the coke-oven gas components on the char charecterlstlcs Braekman-Danheux, C. er al., Fuel, Sep. 1996, 75, (ll), 1274-1278. To improve the economy of the hydropyrolysis process by reducing the hydrogen cost, it has been suggested to use coke-oven gas instead of pure hydrogen. The results presented describe some characteristics of the chars obtained by pyrolysis carried out at 765°C under 3 MPa of various as mixtures sunulating coke-oven gas composition. The char obtained a%ter pyrolysis under coke-oven gas pressure is not fundamentally different from those obtained under inert or hydrogen pressure, at least in porosity, optical texture and oxyreactivity in fiied and fluidized beds. The results show clearlv the oossibiiitv of usinn coke-oven eas for coal ovrolvsis and lead to the c&cl&ion thai synergy between ~metallurgica~ cdkemaking and ‘creaming-off’ coal by hydropyrolysis will be profitable to both processes.

Fuel and Energy Abstrects November 1996 445