06340 A model of pyrolysis of coal particles in a fluidized bed of heat carrier

06340 A model of pyrolysis of coal particles in a fluidized bed of heat carrier

09 Combustion (burners, combustion systems) 96106344 95106337 Mathematical modeling of clearance between the wall of a coke oven and coke cake N...

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Mathematical modeling of clearance between the wall of a coke oven and coke cake Nushiro, K. et al., Tetsu to Hagane, 1995, 81, (a), 625630. (In Japanese) A mathematical model, for estimating the clearance between the wall of a coke oven and the coke mass, is based on the balance between the contraction force and the coking pressure. In this model, the clearance begins to generate when the contraction force exceeds the coking pressure. The contraction force was calculated taking into account the viscoelastic behaviour of the thermal shrinkage of the coke. The coking pressure was calculated considering the generation and the dispersion of the gas in the melting layer.

Non-Isothermal pyrolysls of two klnds of Chinese oil shale Su, J. andYang,J. Fuel Sci. Technol. Int., 1995, 13, (8), 945-956. Non-isothermal pyrolysis of two kinds of Fushun oil shale with particle sizes, ~0.075, 0.3 - 9.5, 0.75 - 1.0 and 1.5 - 2.0 mm has been investigated in a stream (nitrogen) at the flow rate of 100 mUmin by thermogravimetric analyzer at linear heating rate 6.8 K/mitt. It has been found that the temperature intervals of oil-generation from rich grade shale (9.8% Fisher Assay oil yield) and poor grade shale (3.9% Fisher Assay oil yield) with particle size less than 2.0 mm are 400 - 500” and 400 - 526’, respectively.

Mechanism and model of phenols formatlon during 95106336 multistage rotary furnace pyrolysls Pang. Y. et al., Meiran Zhuanhua, 1995, 18, (l), 75-81. (In Chinese) A f&nation-decomposition-competition phenol‘production‘pattem during coal pyrolysis was established. The modeLshows the relation between phenols yield and pyrolysis temperature.

Nonpremlxed flames In sta natlng turbulence Part 96106345 I -The k-e theory wlth equlllbrlum them Bstry for the methane-alr system h&r6F. A. and Libby, P. A. Combustion & Flame, Aug. 1995, 102, (3),

Method for supplylng fuels to gaslfler 95106339 Inumaru, A. et al., (Assigned to) Denryoku Chuo Kenkyujo, JAP. Pat. JP.O6,346,066, Dec. 1994. The Orimulsion, a new fuel prepared by emulsifying Orinoco tar in water,

and coal are supplied into a 2-stage gasifier with a combustor and a reductor, respectively, for combustion and gasification with char recycling. A model of pyrolysls of coal particles In a fluldlzed bed of heat carrier Wu, W. et al., Ranliao Huaxue Xuebao, 1994,522, (4) 406-411. (In Chinese) The behaviour of coal particles in a fluidized bed of heat carrier is vital for designing a fluidized bed coal pyrolyzer, which is a key equipment of new town gas and heat-power cogeneration process. A set of equations reflecting the heat transfer and pyrolysis reaction of coal particles in a fluidized bed of heat carrier was established. By solving these equations by a numerical method, the influences of coal particle size, superfical velocity in the fluidized bed, the temperature, etc. on gas output rate were obtained.

Non premixed turbulent flames in opposed air and methane streams are analyzed on the basis of the k-e theory under conditions of chemical quilibrium. The methane-air system is chosen to permit comparison with existing experimental data. It is found that the thickness of the experimentally observed flames is so large as to preclude application of the current thin flame analyses. Accordingly, the usual thin flame approach is avoided and solutions for the entire flow from the exit plane of one jet to that of the other are obtained. Difficulties are encountered in comparing theory and experiment as a consequence of the flow conditions and the instrumentation used to collect the data. The authors examine the influence of several aerothermochemical quantities on the character of these flames.


95106341 Modeling of nltrlc oxlde formatlon In spark lgnltlon engines wlth a multlzone burned gas Rake, R. R. et al., Combustion & Flake, Aug. 1995, 102, (3), 241-255. A review of the literature on nitroeen oxide concludes that the thermal nitric oxide (NO) mechanism is thi most relevant to the nitrogen oxide emissions from spark ignition engines. The review hai also shown that the use of multiple burned-gas zonesis likely to be important for the accurate prediction of NO emissions. The multizone formulation developed here results in a particuarly efficient formulation, as burning can occur within a zone. Previous multizone spark ignition engine simulations all appear to have created a new zone for each crank-angle increment during combustion. The studv indicated that 5 or 10 burned zones are likelv to be sufficient for mosi purposes. The opportunity was also taken to*compare the NO, predictions, resulting from using different recommendations for the reaction rates in the extended Zeldovich mechanism. 95106342

Modeling varlable denslty effects In turbulent flames-Some basic conslderatlons $lr;yt6k, J. and Nisbet, J. R. Combustion & Flame, Aug. 1995, 102, (3)

The naoer discusses the basic ohvsical ohenomena involved in oressuredensity’ interactions and presents’ modeis of pressure-velocity, pressurescalar, baroclinic and dilatation effects for variable density low Machnumber turbulence. Their implementation in the k-e framework is then described and their performance evaluated. The models assume that both scalar transoort and turbulence neneration arisine from oressure-densitv interactions-in flames are caused Iby the motion of‘ihe large scale turbulent thermals suuemosed on the normal turbulence mechanism. The velocitv of the thermal‘s ii related directly to the mean pressure gradient and local density differences in the flames. It is furthermore assumed that the correction for dilatation effects in the k-e system can be determined from the constraint of conservation of the angular momentum of turbulence per unit mass. 95106343

A modular approach to Increased capacity

95106346 Numerlcal analysis of macro-crack formatlon behavior wlthln lump coke Aoki, H. et al., Kagaku Kogaku Ronbunshu, 1995, 21, (2), 341-348. (In Japanese) Describes thermal stress within lump coke which was studied in order to investigate macro-crack formation and deformation behaviour which strongly influence heat and mass transfer in a coke-oven. The dilatation of the plastic layer, the heating rate dependence of thennophysical and mechanical nronerties of coal and coke. creen in the nlastic and semi-coke lavers. ma&o-crack urooaeation. and .rad&ive hea-t transfer within the macro-crack were coAsi&d in an analytical model.

A numerlcal Invest1 atlon of extlnctlon and lgnltlon 95106347 Ilmlts In lamlnar nonpremlxe 8 counterflowln hydrogen-alr streams for both elementary and reduced them Bstry ;;al&i;hnan, G. et al., Combustion & Flame, Aug. 1995, 102, (3). The structure, extinction and ignition of counterflow hydrogen heated-air systems are investigated for pressures and temperatures of interest in highspeed aerospace applications. A critical assessment of the recent literature is made to determine a chemical-kinetic scheme applicable for the aforementioned conditions of interest. Numerical integrations are performed for various strain rates using a continuation code which handles the singularities in the Jacobian matrix at critical strain-rate parameters. The numerical results with the detailed chemical scheme are wmoared with results obtained from a four-, three-, and two-step reduced chemical-kinetic scheme. Although good agreements for extinction and ignition strain rates are obtained, the two-step mechanism provides rather poor predictions of minor-species concentrations.

Numerlcal studles on the structure of two-dlmen96106346 slonal H,alr premlxed jet flame Katta, V. R. and Roquemore, W. M. Combustion & Flame, Jul. 1995, 102, (l), 21-40. The burning characteristics of premixed Hdair Bunsen-type flame are investigated using a time-dependent, axisymmetric numerical model with variable transport properties and a detailed-chemical-kinetics mechanism. The temperature, species concentration, and velocity fields are investigated under fuel-lean, stoichiometric, and fuel-rich conditions. The calculations show that under fuel-lean conditions the flame exhibits the ‘tip-opening’ phenomenon, while under fuel-rich condition the tip of the flame bums intensely. These results are in agreement with the experimental findings of Mizomoto et al, who have suggested that the tip-opening phenomenon results from the nonunity Lewis number.

MPS, Modern Power Systems, Sep. 1995, 15, (9), 39, 41, 43.

Discusses how many power authorities in the United States must decide how best to meet the needs of a growing population base while providing cost-effective power solutions. One utility, the Sacramento Municipal Utility District - known by its acronym SMUD - had a unique solution. It chose to build four smaller distributed power plants instead of a single large megawatt plant. The article focuses on one of the plants, and discusses the technical and economic advantages of a distributed power system.


Fuel and Energy Abstracts November 1995


solld fuels Durbetakl, P. 507-522.

Numerical study of radlatlve lgnltlon of pyrolyzing et al.,

Int. .I. Numer. Methods Fluids, 1995, 20, (a),

Describes the development of a numerical model of radiative ignition for pyrolyzing solids fuels.