09 Combustion (burners, combustion systems)

solid phase between the components under the experimental con- ditions investigated. The kinetic parameters associated with the bagasse/petroleum residue mixture involved the sum of bagasse and petroleum residue individual component kinetic parameters. The information obtained can be used to develoo a correlation between the thermogravimetric data and the feedstock’composition.

02/01619 Coal-firing combustor with melting treatment of combustion ashes Okazaki, H. er al. Jpn. Kokai Tokkyo Koho JP 2001 289,408 (Cl. F23C11/00), 19 Ott 2001, Appl. 2000/113,210, 10 Apr 2000. 8. (In Japanese) The apparatus includes a boiler for combustion of powdered coal to generate combustion ashes, a melting furnace for melting treatment of the ashes to generate combustion gas, a pipeline for recycling the combustion gas back to upstream the burner of the boiler for reduction reaction of NO, in the gas by burner flame, and a means for further denitration of the gas.

02/01620 Coke combustion efficiency in sintering Trisc, A. Meralurgija (Zagreb), 2001, 40, (3), 143-146. The aim of this work was to determine conditions at which sinter quality is stable and fuel consumption is lower. The study of the coke combustion efficiency in sintered bed was carried out on laboratory scale. During experiments the sucked-out air rate was controlled in interval from 10 to 55 cm/s. The concentration of CO, COz in waste gases and temperatures in sintered bed and temperature of waste gases were recorded. By decreasing the sucked-out air rate the coke combustion efficiency (ratio CO&O) increases. At the same time, temperature in the sintered bed increases and amount of the heat conducted away reduces.

02/01621 Combustion characteristics of a heat- recirculating ceramic burner using a low-calorific-fuel Tanaka, R. et al. Energy Conversion and Management, 2001, 42, (15- 17). 1897-1907. A’new type of the heat recirculating burner was constructed and its combustion characteristics during steady low-calorific-fuel/air combus- tion were investigated. Flammability limits of the burner were measured by experiments, and longitudinal temperature distributions of air and burned gas flowing in the passes of the burner were determined by means of both experimental measurements and numerical simulations. Using the heat recirculation rate and the thermal efficiency as criteria for the performance of the burner, the optimal design of the burner was examined in terms of a chemical parameter (the equivalence ratio), a fluid-mechanical parameter (the Reynolds number) and a geometrical parameter (the number of passes).

02/01622 Combustion characteristics of high ash coal in a pulverized coal combustion Kurose, R. ef al. Fuel, 2001, 80, (IO), 1447-1455. The influences of ash content on pulverized coal combustion characteristics are experimentally and numerically studied under a staged combustion condition. The stage combustion ration (the ratio of air volume of the staged combustion air to the total air) is 0 or 30%, and the coals tested are the three high ash coals with different ash contents of 36, 44 and 53 wt%, which were separated using the floatation method. The results show that as the ash content increases, gas temperature decreases and Oz consumption and NO, formation becomes slow near the burner. Also, the increase of the ash content leads to the increase in NO, concentration and unburned carbon fraction at the furnace exit. The reasons being, for the high ash coal, the large heat capacity of the ash and the covering of combustible matter suppress combustibility with ash during the char oxidization. The numerical simulations designed to match the experimental setup for the staged combustion show that the numerical results are in general agreement with the measurements.

02/01623 Comparative second-law analysis of internal combustion engine operation for methane, methanol, and dodecane fuels Rakopoulos, CD. and Kyritsis, D.C. Energy, 2001, 26, (7). 705-722. A method for both combustion irreversibility and working medium availability computations in a high-speed, naturally-aspirated, four- stroke, internal combustion engine cylinder is presented. The results of the second-law analysis of engine operation with n-dodecane (n- CizHze) fuel are compared with the results of a similar analysis for cases where a light, gaseous (CH,) and an oxygenated (CHsOH) fuel is used. The rate of entropy production during combustion is analytically calculated as a function of the fuel reaction rate with the combined use of first- and second-law arguments and a chemical equilibrium hypothesis. It is shown theoretically that the decomposition of lighter molecules leads to less entropy generation compared to heavier fuels. This is verified computationally for the particular fuels and the

corresponding decrease in combustion irreversibility is calculated. Special reference is made to the effect of the lower mixing entropy of the exhaust gas of an oxygenated fuel (CHsOH) as a contribution to the discussion of the advantages and disadvantages of the use of such fuels.

02lO1624 Computer simulation of the process of coal and methane interactton with air Stefanik, Y.V. et al. Geol. Geokhim. Goryuch. Kopalin, 2001, 1, 86-91. (In Ukrainian) In this study the molecular dynamics method was used in conjunction with semi-empirical methods of quantum chemistry to perform a computer simulation of methane and coal combustion in air. The thermodynamic and kinetic parameters obtained suggest the possibility of obtaining an optimal temperature of realization of the process.

02/01625 Determination of sulfur content and implementation of a circulating fluidized bed process Santana, E. er al. Recenrs Prog. Genie Procedes, 2001, 15, (77), 181-186. (In Franchl Combustion chamber injection of calcareous sorbents for the control of SOz emissions from circulating fluidized bed combustion of coal and monitoring of the process by analysis of flue gases and ashes is discussed.

02/01626 Effect of heating rate on structural changes of heat-treated coals Takandhashi, T. et al. Tetsu to Hagane, 2001, 87, (6), 454-458. (In Japanese) For high-caking Goonyella and low-caking Witbank coals, dynamic viscoelasticity was measured at heating rates of 3-80”C/min. An increase in heating rate shifted the temperature which gives the maximum fusibility to higher temperature. Structural analyses (solvent extraction, ultimate analysis and IT-IR measurement) for the heat- treated coals showed that the temperature which the extraction yields, H/C atmospheric ratio and aromaticity greatly change also shifted to higher temperature by increasing heating rate, while (O+S)/C atmospheric ratio was not influenced by the heating rate so much. The enhanced fusibility by an increase in heating rate can be the result of decrease in possibility of crosslinking related to oxygen and sulfur functionalities.

02/01627 Effect of leaching on the ash behavior of wheat straw and olive residue during fluidized bed combustion Arvelakis, S. er al. Biomass and Bioenergy, 2001, 20, (a), 459-470. Fluidized bed combustion has been proven to be an attractive method for the conversion of agroresidues to energy offering economical and environmental benefits. The low melting point ash of agroresidues cause a number of problems e.g., sintering, agglomeration, deposition, etc., which consist the main obstacles for economical and viable application of this conversion method. Leaching that is considered to be a low cost pretreatment technique for the elimination of ash related problems in biomass boilers studied here. The produced results clearly demonstrate that leaching could help significantly to reduce the ash related problems caused during the operation of fluidized bed combustors with biomass.

02lO1626 Effects of co-combustion of secondary fuels on fly ash quality Lamers, F.J.M. et a/. Am. Concr. Insr., SP, 2001, (SP-199) 433-457. In the Netherlands the government allows the co-combustion of a

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maximum of 10% of secondary fuels together with coal. To show whether the quality of fly ashes is affected by co-combustion, a broad research program was performed in which both the technical and the environmental quality of concrete with fly ashes from co-combustion were evaluated in comparison to the quality of concrete with ref. fly ashes. In the research oroeram. flv ashes from co-combustion of sewaee sludge, paper sludge,‘Per cokes-(from oil refining), several types ;f biomass and a type of liquid hydrocarbon were evaluated. Both the technical and the environmental quality of most, ashes from co- combustion were shown to be comparable to that of regular fly ashes. As a result of the outcomes of the research program the Dutch regulations for fly ash as a filler or part of the cementitious material were adjusted to make utilization of fly ashes from co-combustion possible. European legislation is in preparation.

02/01629 Effects of moisture in coal on pulverized coal combustion characteristics Kurose, R. et al. Fuel, 2001, 80, (IO), 1457-1465. Effects of moisture in coal on pulverized coal combustion character- istics are investigated by means of a three-dimensional numerical simulation. The results show that as the moisture increases, flame temperature and NO., mole fraction decrease, while 02 mole fraction increases in the region near the burner, and the peaks of the flame temperature and NO, mole fraction shift downstream. Also, the

266 Fuel and Energy Abstracts May 2002