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03872 An experimental investigation of thermal characteristics in a 12-MWth CFB boiler
09
Combustion
(burners, combustion
systems)
09 COMBUSTION
08 STEAM RAISING
Burners, Combustion Systems Boiler Operation/Design
95103674
Air
staging
of
a CFB combustor
-
design
considerations
calcula-
Wang, X. S. et al., IChemE Res. Event, Two-Day Symp., Inst. Chemical Engineers, Rugby, UK, 1994, 2, 5§9-561. The authors examine the performance of coal combustion in a circulating fluidized bed with combustion-air staging. It was found that bed hydrodynamics, combustion behaviour and emission were all affected by secondary air injection. In the design of a circulating fluidized bed combustor a balance must be struck between the sometimes conflicting requirements of combustion erformance and emission control. The effect of hydrodynamic behaviour o P.circulating fluidized bed on the combustion and on the generation of pollutants must be carefully considered at the design stage.
boilers.
95103675
95103665
Bolter gross efficiency calculation with indirect method during calcium compound dosage to furnace chamber
Soba, J. Energetyka, 1994, 48, (lo), -370-373. (In Polish) Describes the modified standard method of boiler gross efficiency tion with indirect method.
Combination and condensing 95103666 Heat. Vent. Plumb., Feb. 1995, 16, (4), 25-47. Presents 5 short articles on domestic combination
95103667
boilers and condensing
Computer assistance in evaluation in power boilers
of combustion
Szafran, R. Gospod. Paliwami Energ., 1994, 42, (l), 2-6. (In Polish) Presents an algorithm of a computer program supporting the evaluation of quality of fossil fuel combustion process in power boilers.
Analysis of reactions in the grid zone of a contlnuous jetting fluidized coal gasifiar
Uemiya, S. et al., Kagaku Kogaku Ronbunshu, 1994, 20, (6), 805-812. (In Japanese) Gasification of Taiheiyo coal semicoke was conducted in continuous fluidized-bed coal gasifier with a centre nozzle and conical distributor. The effects of bed temperature and jet velocity on gas concentration profiles were investigated at different levels of carbon conversion.
Analytical approximations for structures of wet CO 95103676 flames with one-step reduced chemistry Convective boiling and condensation 95103666 Collier, J. and Thome, J. 3rd Edition, Oxford Universiv Press, 1994, 596 PP. Creep strain bahaviour In a lZ%CrMoV steal 95103669 Wu, R. et al., Materials at High Temperatures, 1994, 12, (4), 277-283. Uniaxial creep tests at 80 MPa with different temperatures and at 600°C with different loads were carried out for a lZ%CrMoV martensitic steel. The creep strain behaviour was analysed using an analytical expression where the creep strain rate is proportional to the exponential of the creep strain. The creep curves, rupture time and strains could be well reproduced. The observed and predicted rupture times satisfied the Monkman-Grant relationship.
Rightley, M. L. and Williams, F. A. Combustion & Flame, May 1995, 101, (3), 287-301. Since hydrogen-containing species catalyze CO oxidation, at small H/C and H/O ratios steady-state approximations for reaction intermediaries should be accurate and should produce a good one-step reduced-chemistry approximation for describing the flame structure. Such an approximation is complicated, however, because of the many elementary kinetic steps involved. In the present work simplifications are introduced into a one-step approximation that enable analytical expressions to be obtained for the burning velocities of premixed laminar flames by asymptotic methods. The resulting burning velocities are shown to be in good agreement with experiment and with detailed numerical predictions, and qualitative aspects of the internal flame structure are shown to agree with those deduced from full-chemistry numerical calculations. 95103677
Apparatus and method for retorting oil shale and
like materials Design for a low-emission boiler system (LEBS) 95103670 PETC Review, Spring 1995, (ll), p. 46. A short report on the design of a low-emission boiler system completed by three industry teams led by ABBiCombustion Engineering, Babcock & Wilcox, and Riley Stoker Corporation.
95103671
Evaluating boiler efficiency
Coerper, P. Plant Engng., Jan. 1995, 49, (l), 66-68. Discusses the five elements which affect boiler ‘efficiency.
Strumskis, L. (Assigned to) Georgia Oil & Gas Co. Inc., US Pat. US.5,360,537, Nov. 1994.
Application of a general gas-solid reaction model 95103676 to flash pyrolysis of wood in a circulating fluidizad bad Hastaoglu, M. A. and Hassam, M. S. Fuel, May 1995, 74, (S), 697-703. Flash pyrolysis of wood in a circulating fluidized bed is studied. The results of a comprehensive gas-solid reaction model are used successfully in analysing the system. The changes in the structure, the transient nature of heat and mass transfer and the reaction scheme are accounted for. Al1 the structural parameters and thermophysical properties are used as continuously changing variables.
The asymptotic structure of inhibited nonpremixed methane-air flames Seshadri,K. and Ilincic, N. Combustion & Flame, May 1995, 101, (3),
95103679 95103672
An experimental investigation istics in a 12-MW,, CFB boiler
of thermal character-
Golriz, M. R. and Sunden, B. Experimental Heal Transfer, Jul.-Sep. 1994, 7, (3), 217-233. Temperature distributions and local heat transfer coefficients were measured with shielded thermocouple probes and a heat flux meter, respectively. The measurements were carried out in the combustion chamber of a 12-MW,, circulating fluidized bed boiler. Effects of the bed bulk temperature, the suspension density, the superficial gas velocity, and the shape of the heat transfer surfaces on the temperature distribution and heat transfer coefficient were investigated.
271-294. An asymptotic analysis is perfor;d to determine the influence of CF,Br on the structure and extinction of nonpremixed methane-air flames. The inhibitor CF,Br is added to the air-stream of the diffusion flame. A reduced four-step mechanism is used to describe the chemistry taking place in the reaction zone. The outer structure of the flame, in the limit where the rates of the chemical reactions are infinitely fast, is found to consist of two infinitely thin nonpremixed reaction zones which are separated by a chemically inert region. Previous analysis has shown that these reaction zones must merge at conditions close to extinction. Therefore only the asymptotic structure of the merged flame is analyzed here.
95103673
The asymptotic structure of nonpremixed methane95103660 air flames with oxidizer IeaXage of order unity
Optimization
of reheat pressures in thermal power
plants Habib, M. A. et al., Energy, Jun. 1995, 20, (6), 555-565. The authors present a procedure for optimization of the first and second reheat pressures in thermal power plants. The analysis is based on the firstlaw efficiency and exergy-balance equations. For analysis, the plant is divided into two main units (the steam generator and the turbine cycle). The results indicate that a range of first and second reheat pressures satisfy different constraints. Improvements in the plant second-law efficiency with increased reheat pressure are due to improvements in the turbine-cycle unit. Exergy destruction in the steam generator, which accounts for more than half of the exergy destruction in the power plant, is not significantly affected by reheat pressures.
Seshadri, K. and Ilincic, N. Combusrion & Flame, Apr. 1995, 101, (1). 69-80. The asymptotic structure of nonpremixed methane-air flames is analyzed using a reduced three-step mechanism. The three global steps of this reduced mechanism are similar to those used in a previous analysis. The rates of the three steps are related to the rates of thk elementary ieactions appearing in the C, mechanism for oxidation of methane. The present asymptotic analysis differs from the previous analysis in that oxygen is presumed to leak from the reaction zone to the leading order. Chemical reactions are presumed to occur in three asymptotically thin layers: the fuel-consumption layer, the nonequilibrium layer for the water-gas shift reaction and the oxidation layer.
Fuel and Energy Abstracts
July 1995 277
Combustion
(burners, combustion
systems)
09 COMBUSTION
08 STEAM RAISING
Burners, Combustion Systems Boiler Operation/Design
95103674
Air
staging
of
a CFB combustor
-
design
considerations
calcula-
Wang, X. S. et al., IChemE Res. Event, Two-Day Symp., Inst. Chemical Engineers, Rugby, UK, 1994, 2, 5§9-561. The authors examine the performance of coal combustion in a circulating fluidized bed with combustion-air staging. It was found that bed hydrodynamics, combustion behaviour and emission were all affected by secondary air injection. In the design of a circulating fluidized bed combustor a balance must be struck between the sometimes conflicting requirements of combustion erformance and emission control. The effect of hydrodynamic behaviour o P.circulating fluidized bed on the combustion and on the generation of pollutants must be carefully considered at the design stage.
boilers.
95103675
95103665
Bolter gross efficiency calculation with indirect method during calcium compound dosage to furnace chamber
Soba, J. Energetyka, 1994, 48, (lo), -370-373. (In Polish) Describes the modified standard method of boiler gross efficiency tion with indirect method.
Combination and condensing 95103666 Heat. Vent. Plumb., Feb. 1995, 16, (4), 25-47. Presents 5 short articles on domestic combination
95103667
boilers and condensing
Computer assistance in evaluation in power boilers
of combustion
Szafran, R. Gospod. Paliwami Energ., 1994, 42, (l), 2-6. (In Polish) Presents an algorithm of a computer program supporting the evaluation of quality of fossil fuel combustion process in power boilers.
Analysis of reactions in the grid zone of a contlnuous jetting fluidized coal gasifiar
Uemiya, S. et al., Kagaku Kogaku Ronbunshu, 1994, 20, (6), 805-812. (In Japanese) Gasification of Taiheiyo coal semicoke was conducted in continuous fluidized-bed coal gasifier with a centre nozzle and conical distributor. The effects of bed temperature and jet velocity on gas concentration profiles were investigated at different levels of carbon conversion.
Analytical approximations for structures of wet CO 95103676 flames with one-step reduced chemistry Convective boiling and condensation 95103666 Collier, J. and Thome, J. 3rd Edition, Oxford Universiv Press, 1994, 596 PP. Creep strain bahaviour In a lZ%CrMoV steal 95103669 Wu, R. et al., Materials at High Temperatures, 1994, 12, (4), 277-283. Uniaxial creep tests at 80 MPa with different temperatures and at 600°C with different loads were carried out for a lZ%CrMoV martensitic steel. The creep strain behaviour was analysed using an analytical expression where the creep strain rate is proportional to the exponential of the creep strain. The creep curves, rupture time and strains could be well reproduced. The observed and predicted rupture times satisfied the Monkman-Grant relationship.
Rightley, M. L. and Williams, F. A. Combustion & Flame, May 1995, 101, (3), 287-301. Since hydrogen-containing species catalyze CO oxidation, at small H/C and H/O ratios steady-state approximations for reaction intermediaries should be accurate and should produce a good one-step reduced-chemistry approximation for describing the flame structure. Such an approximation is complicated, however, because of the many elementary kinetic steps involved. In the present work simplifications are introduced into a one-step approximation that enable analytical expressions to be obtained for the burning velocities of premixed laminar flames by asymptotic methods. The resulting burning velocities are shown to be in good agreement with experiment and with detailed numerical predictions, and qualitative aspects of the internal flame structure are shown to agree with those deduced from full-chemistry numerical calculations. 95103677
Apparatus and method for retorting oil shale and
like materials Design for a low-emission boiler system (LEBS) 95103670 PETC Review, Spring 1995, (ll), p. 46. A short report on the design of a low-emission boiler system completed by three industry teams led by ABBiCombustion Engineering, Babcock & Wilcox, and Riley Stoker Corporation.
95103671
Evaluating boiler efficiency
Coerper, P. Plant Engng., Jan. 1995, 49, (l), 66-68. Discusses the five elements which affect boiler ‘efficiency.
Strumskis, L. (Assigned to) Georgia Oil & Gas Co. Inc., US Pat. US.5,360,537, Nov. 1994.
Application of a general gas-solid reaction model 95103676 to flash pyrolysis of wood in a circulating fluidizad bad Hastaoglu, M. A. and Hassam, M. S. Fuel, May 1995, 74, (S), 697-703. Flash pyrolysis of wood in a circulating fluidized bed is studied. The results of a comprehensive gas-solid reaction model are used successfully in analysing the system. The changes in the structure, the transient nature of heat and mass transfer and the reaction scheme are accounted for. Al1 the structural parameters and thermophysical properties are used as continuously changing variables.
The asymptotic structure of inhibited nonpremixed methane-air flames Seshadri,K. and Ilincic, N. Combustion & Flame, May 1995, 101, (3),
95103679 95103672
An experimental investigation istics in a 12-MW,, CFB boiler
of thermal character-
Golriz, M. R. and Sunden, B. Experimental Heal Transfer, Jul.-Sep. 1994, 7, (3), 217-233. Temperature distributions and local heat transfer coefficients were measured with shielded thermocouple probes and a heat flux meter, respectively. The measurements were carried out in the combustion chamber of a 12-MW,, circulating fluidized bed boiler. Effects of the bed bulk temperature, the suspension density, the superficial gas velocity, and the shape of the heat transfer surfaces on the temperature distribution and heat transfer coefficient were investigated.
271-294. An asymptotic analysis is perfor;d to determine the influence of CF,Br on the structure and extinction of nonpremixed methane-air flames. The inhibitor CF,Br is added to the air-stream of the diffusion flame. A reduced four-step mechanism is used to describe the chemistry taking place in the reaction zone. The outer structure of the flame, in the limit where the rates of the chemical reactions are infinitely fast, is found to consist of two infinitely thin nonpremixed reaction zones which are separated by a chemically inert region. Previous analysis has shown that these reaction zones must merge at conditions close to extinction. Therefore only the asymptotic structure of the merged flame is analyzed here.
95103673
The asymptotic structure of nonpremixed methane95103660 air flames with oxidizer IeaXage of order unity
Optimization
of reheat pressures in thermal power
plants Habib, M. A. et al., Energy, Jun. 1995, 20, (6), 555-565. The authors present a procedure for optimization of the first and second reheat pressures in thermal power plants. The analysis is based on the firstlaw efficiency and exergy-balance equations. For analysis, the plant is divided into two main units (the steam generator and the turbine cycle). The results indicate that a range of first and second reheat pressures satisfy different constraints. Improvements in the plant second-law efficiency with increased reheat pressure are due to improvements in the turbine-cycle unit. Exergy destruction in the steam generator, which accounts for more than half of the exergy destruction in the power plant, is not significantly affected by reheat pressures.
Seshadri, K. and Ilincic, N. Combusrion & Flame, Apr. 1995, 101, (1). 69-80. The asymptotic structure of nonpremixed methane-air flames is analyzed using a reduced three-step mechanism. The three global steps of this reduced mechanism are similar to those used in a previous analysis. The rates of the three steps are related to the rates of thk elementary ieactions appearing in the C, mechanism for oxidation of methane. The present asymptotic analysis differs from the previous analysis in that oxygen is presumed to leak from the reaction zone to the leading order. Chemical reactions are presumed to occur in three asymptotically thin layers: the fuel-consumption layer, the nonequilibrium layer for the water-gas shift reaction and the oxidation layer.
Fuel and Energy Abstracts
July 1995 277