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04136 Gas-solid flow in the riser of a circulating fluidized bed
09
Combustion (burners, combustion systems)
Formation of solid deposits In the gas circuit of a 96104133 pressurlzed fluldlzed bed combustion plant Souto, M. A. et al., Fuel, May 1996, 75, (6), 675-680. Analysis of solid deposits from the gas circuit of the pressurized fluid bed combustion (PFBC) plant in Escatron (NE Spain) showed them to be mainly composed of particles of anhydrite (CaSO,) with a mean diameter of 6 urn, cemented by a partially devitrified glassy matrix comprising complex sulphates, including langbeinite, K,Mg,(SO,),.
Further studies on effects of thermophoresls on 96104 134 seedlng particles In LDV measurements of stralned flames Sung, C. J. et al., Combusfion & Flame, Apr. 1996, 105, (I), 189-201. The axial velocity profiles for counterflow premixed and diffusion flames were experimentally measured by laser-doppler velocimetry (LDV) and computationally simulated with detailed reaction mechanism and transport properties.
Gas In ectlon as a measure to reduce N,O emls96104 135 of coal slons from fluldlze d bed combustion Marban, G. et al., Coal Sci. Technol., 1995, 24, (2), 1915-1918. The paper discusses how up to 99% N,O reduction was achieved in fluidized coal combustion with injection of additional fuel gases (e.g. CH, and propane), which form a hot-temperature region inside the freeboard, cyclone, or downstream of the bed. The reaction rate for N 0 decomposition in the flame was lo-15 times higher than that achieve d by the empty reactor at the same temperature. This supports a radical N,O decompositon mechanism in the flame chemistry.
Gas-solld flow In the riser of a clrculatlng fluldlzed 96104136 bed He, Y. and Rudolph, V. Chem. Eng. Sci., 1995, 50, (21), 3443-3453. A new approach to the modelling of gross gas-solids flow through the riser in a circulating fluidized-bed system was proposed. Previous approaches were theoretically incorrect because they were based on a fundamental analysis of the riser process hydrodynamics. Experimental results from a compartmental dense-phase circulating fluidized bed, developed for a continuous coal combustion gasification proces. verified the existence of the two flow regime.
A general
mathematical
model
of Chinese
CFBC
Xu, X. and Li, Z. Prog. Nar. Sci., 1995, 5, (6), 696-702. In the mathematical modelling of circulating fluidized bed combustion (CFBC) the emphasis is placed on taking into account the wide size distribution of bed Inventory. Some aspects such as hydrodynamics, devolatilization of coal, combustion of char and the formation and reduction of harmful substances are considered in detail in order to describe the process precisely. By using the model, simulation is carried out with a Chinese CFBC boiler with a steam generating capacity of 35 t/h.
96104136 High strain-rate impact studies of predamaged rocket ropellants. I. Characterization of damage using a cumulative cfamage failure criterion Ho, S. Y. Combusriorl & Flame, Mar. 1996, 104, (4), 524-534. The effect of predamage on the high strain-rate behaviour, ignition sensitivity, and impact ignition mechanism of a HTPBiAP rocket propellant was assessed using a modified Hopkinson Bar. Damage was induced by constant stress and monotonic tension tests prior lo testing on the modified Hopkinson Bar. Predamage was characterized using a failure criterion based on a linear Cumulative Damage model. Creep and recovery experiments were conducted to determine the amount of recovery (due to relaxation or viscoelastic effects) and rehealing of damage (nonrecoverable strain), and the effect of recovery time on the induced mechanical damage. The effect if residual void volume on the impact ignition sensitivity and mechanism for freshly damaged, rehealed, and undamaged propellant samples was also investigated. 96104139 The influence of fuel composition on emissions of CO, NO, and NO, from a gas-fired pulsed combustor Jones, H. R. and Leng, .I. Combusrio!l & Flame, Mar. 1996, 104, (4) r,rl “?n ‘+l7’-43”. Describes a commercially available heater designed to burn natural gas of NO, and CO using a wide range In particular, the effect of addition been investigated.
nonpremixed pulsed combustion room which has been used to study emissions of fuel flowrates and fuel composilions. of hydrogen and propane to the fuel has
96104140 Influence of structure of polymeric fuels on the combustion behaviour of composite solid propellants Kishore, K. and Sridhara, K. Fuel, May 1996, 75, (7), 912-918. This is a first report in which the influence of the structure of polymeric binders, such as molecular weight (M), end-group functionality and cisvans proportion, on the combustion behaviour of composite solid propellants has been examined.
266
Fuel and Energy
Abstracts
July
1996
Influence of the fineness of coal and llgnlte on the 96104141 flame formatlon In rotary cement kilns Seidel, G. ZKG fnt., 1995, 48, (ll), 588-591. Describes a method for evaluating fuels which has been developed using the tailor-made model, for requirements in a clinker-burning process. The effects of the burner, combustion space, and fuel were considered. Simulation calculations showed that the flame temperature and shape, and heat transfer to the kiln feed were the main factors affecting the coal grinding.
lnhlbltlon of premlxed methane-alr flames by 96104142 fluoromethanes Linteris, G. T. and Truett, L. Combushm & Flame, Apr. 1996, 105, (l), 15-27. The paper presents the first calculations and measurements of the burning velocity of premixed hydrocarbon flames inhibited by the three one-carbon fluorinated species CH,F,, CF,H, and CF,. The chemistry of these agents is expected to be similar to that of some agents that may be used as replacements for CF,Br, so that studying their behaviour in methane flames provides an important first step towards understanding the suppression mechanism of hydrocarbon fires by fluorinated compounds.
lnteractlons between water, tars and coke during 96104143 coal pyrolysls Mansuy, L. er al., Coal Sci. Tech&., 1995, 24, (l), 861-864. Discusses the interactions of water during confined pyrolysis of a vitriniterich coal.
Klnetlc parameters for heterogenous boron com96104144 bustlon reactlons vla the Cluster Beam approach Smolanoff, J. et al., Combusriort & Flame, Apr. 1996, 105, (l), 68-79. In the Cluster Beam method, singly ionized clusters of controlled size and composition are used as experimental ‘models’ of macroscopic surfaces. Within this framework, it is possible to predict product distribution and kinetic parameters for elementary surface reactions over a wide range of temperatures and surface compositions. In some case also derive thermodynamic information relevant to elementary reaction products and reaction intermediates. The fundamental assumptions, experimental methods, and data analysis techniques are described and estimates are given for the reliability of Cluster Beam predictions.
Kinetic studies on low temperature, dry flue gas 96104145 desulfurization Aichinger, G. er al., Coal Sci. Teclmol., 1995, 24, (2). 1859-1862. The paper describes how the impregnated coal fly ash-industrial hydrated lime sorbents were evaluated for Sq2 removal in low-temperature dry flue gas desulphurization. The most crucial parameter for reactivity of lime was the relative humidity, which, at higher values enhanced desulphurization, presumably by formation of a water film on the sorbent surface.
96/04146 Kinetic study of char combustion in a fluidized bed Brunello, S. et al., Fuel, Apr. 1995, 75, (5), 536-544. Experiments were carried out with eight different chars in a batch fluidized bed reactor. The combustion rate was determined by measuring the CO and CO, concentrations in the flue gas. Four models were tested, but only two well described the combustion rate for all tested chars. The effect of temperature and particle size on the combustion rate and the rate-controlling step (chemical or diffusion) were determined. With small particle size, the temperature dependence of reaction rate constant was determined and expressed by the Arrhenius equation, providing the apparent activation energy and the pre-exponential factor. The experiments were extended to larger particle size and the temperature dependence of the reaction rate constant was analysed.
96104147 Laboratory studies on devolatilization and char oxidation under PFBC conditions. 1. Volatile release and char reactivity Lu, Y. E/iergy Fuels, 1996, 10, (2), 348-356. Discusses the characterization of solid fuels during devolatilization and semicoke oxidation under pressurized fluidized-bed combustion conditions in a laboratory-scale batch reactor under well-defined operating conditions.
Laboratory studies on devolatilization and char 96104146 oxidation under PFBC conditions. 2. Fuel nitrogen conversion to nitrogen oxides Lu, Y. &ergy fuels. 1996, 10, (2), 357-363. Discusses the fuel nitrogen release, its conversion to NO,, and semicoke oxidation, in pressurized fluidized-bed combustion in a well-controlled laboratory-scale batch reactor at the base operating conditions of 850”, 11 bars, 3% (vol./vol.) 0, concentration, and fluidization velocity 0.24 m/s, for 10 fuels ranging from high-volatile peat to relatively low-volatile coke.
Combustion (burners, combustion systems)
Formation of solid deposits In the gas circuit of a 96104133 pressurlzed fluldlzed bed combustion plant Souto, M. A. et al., Fuel, May 1996, 75, (6), 675-680. Analysis of solid deposits from the gas circuit of the pressurized fluid bed combustion (PFBC) plant in Escatron (NE Spain) showed them to be mainly composed of particles of anhydrite (CaSO,) with a mean diameter of 6 urn, cemented by a partially devitrified glassy matrix comprising complex sulphates, including langbeinite, K,Mg,(SO,),.
Further studies on effects of thermophoresls on 96104 134 seedlng particles In LDV measurements of stralned flames Sung, C. J. et al., Combusfion & Flame, Apr. 1996, 105, (I), 189-201. The axial velocity profiles for counterflow premixed and diffusion flames were experimentally measured by laser-doppler velocimetry (LDV) and computationally simulated with detailed reaction mechanism and transport properties.
Gas In ectlon as a measure to reduce N,O emls96104 135 of coal slons from fluldlze d bed combustion Marban, G. et al., Coal Sci. Technol., 1995, 24, (2), 1915-1918. The paper discusses how up to 99% N,O reduction was achieved in fluidized coal combustion with injection of additional fuel gases (e.g. CH, and propane), which form a hot-temperature region inside the freeboard, cyclone, or downstream of the bed. The reaction rate for N 0 decomposition in the flame was lo-15 times higher than that achieve d by the empty reactor at the same temperature. This supports a radical N,O decompositon mechanism in the flame chemistry.
Gas-solld flow In the riser of a clrculatlng fluldlzed 96104136 bed He, Y. and Rudolph, V. Chem. Eng. Sci., 1995, 50, (21), 3443-3453. A new approach to the modelling of gross gas-solids flow through the riser in a circulating fluidized-bed system was proposed. Previous approaches were theoretically incorrect because they were based on a fundamental analysis of the riser process hydrodynamics. Experimental results from a compartmental dense-phase circulating fluidized bed, developed for a continuous coal combustion gasification proces. verified the existence of the two flow regime.
A general
mathematical
model
of Chinese
CFBC
Xu, X. and Li, Z. Prog. Nar. Sci., 1995, 5, (6), 696-702. In the mathematical modelling of circulating fluidized bed combustion (CFBC) the emphasis is placed on taking into account the wide size distribution of bed Inventory. Some aspects such as hydrodynamics, devolatilization of coal, combustion of char and the formation and reduction of harmful substances are considered in detail in order to describe the process precisely. By using the model, simulation is carried out with a Chinese CFBC boiler with a steam generating capacity of 35 t/h.
96104136 High strain-rate impact studies of predamaged rocket ropellants. I. Characterization of damage using a cumulative cfamage failure criterion Ho, S. Y. Combusriorl & Flame, Mar. 1996, 104, (4), 524-534. The effect of predamage on the high strain-rate behaviour, ignition sensitivity, and impact ignition mechanism of a HTPBiAP rocket propellant was assessed using a modified Hopkinson Bar. Damage was induced by constant stress and monotonic tension tests prior lo testing on the modified Hopkinson Bar. Predamage was characterized using a failure criterion based on a linear Cumulative Damage model. Creep and recovery experiments were conducted to determine the amount of recovery (due to relaxation or viscoelastic effects) and rehealing of damage (nonrecoverable strain), and the effect of recovery time on the induced mechanical damage. The effect if residual void volume on the impact ignition sensitivity and mechanism for freshly damaged, rehealed, and undamaged propellant samples was also investigated. 96104139 The influence of fuel composition on emissions of CO, NO, and NO, from a gas-fired pulsed combustor Jones, H. R. and Leng, .I. Combusrio!l & Flame, Mar. 1996, 104, (4) r,rl “?n ‘+l7’-43”. Describes a commercially available heater designed to burn natural gas of NO, and CO using a wide range In particular, the effect of addition been investigated.
nonpremixed pulsed combustion room which has been used to study emissions of fuel flowrates and fuel composilions. of hydrogen and propane to the fuel has
96104140 Influence of structure of polymeric fuels on the combustion behaviour of composite solid propellants Kishore, K. and Sridhara, K. Fuel, May 1996, 75, (7), 912-918. This is a first report in which the influence of the structure of polymeric binders, such as molecular weight (M), end-group functionality and cisvans proportion, on the combustion behaviour of composite solid propellants has been examined.
266
Fuel and Energy
Abstracts
July
1996
Influence of the fineness of coal and llgnlte on the 96104141 flame formatlon In rotary cement kilns Seidel, G. ZKG fnt., 1995, 48, (ll), 588-591. Describes a method for evaluating fuels which has been developed using the tailor-made model, for requirements in a clinker-burning process. The effects of the burner, combustion space, and fuel were considered. Simulation calculations showed that the flame temperature and shape, and heat transfer to the kiln feed were the main factors affecting the coal grinding.
lnhlbltlon of premlxed methane-alr flames by 96104142 fluoromethanes Linteris, G. T. and Truett, L. Combushm & Flame, Apr. 1996, 105, (l), 15-27. The paper presents the first calculations and measurements of the burning velocity of premixed hydrocarbon flames inhibited by the three one-carbon fluorinated species CH,F,, CF,H, and CF,. The chemistry of these agents is expected to be similar to that of some agents that may be used as replacements for CF,Br, so that studying their behaviour in methane flames provides an important first step towards understanding the suppression mechanism of hydrocarbon fires by fluorinated compounds.
lnteractlons between water, tars and coke during 96104143 coal pyrolysls Mansuy, L. er al., Coal Sci. Tech&., 1995, 24, (l), 861-864. Discusses the interactions of water during confined pyrolysis of a vitriniterich coal.
Klnetlc parameters for heterogenous boron com96104144 bustlon reactlons vla the Cluster Beam approach Smolanoff, J. et al., Combusriort & Flame, Apr. 1996, 105, (l), 68-79. In the Cluster Beam method, singly ionized clusters of controlled size and composition are used as experimental ‘models’ of macroscopic surfaces. Within this framework, it is possible to predict product distribution and kinetic parameters for elementary surface reactions over a wide range of temperatures and surface compositions. In some case also derive thermodynamic information relevant to elementary reaction products and reaction intermediates. The fundamental assumptions, experimental methods, and data analysis techniques are described and estimates are given for the reliability of Cluster Beam predictions.
Kinetic studies on low temperature, dry flue gas 96104145 desulfurization Aichinger, G. er al., Coal Sci. Teclmol., 1995, 24, (2). 1859-1862. The paper describes how the impregnated coal fly ash-industrial hydrated lime sorbents were evaluated for Sq2 removal in low-temperature dry flue gas desulphurization. The most crucial parameter for reactivity of lime was the relative humidity, which, at higher values enhanced desulphurization, presumably by formation of a water film on the sorbent surface.
96/04146 Kinetic study of char combustion in a fluidized bed Brunello, S. et al., Fuel, Apr. 1995, 75, (5), 536-544. Experiments were carried out with eight different chars in a batch fluidized bed reactor. The combustion rate was determined by measuring the CO and CO, concentrations in the flue gas. Four models were tested, but only two well described the combustion rate for all tested chars. The effect of temperature and particle size on the combustion rate and the rate-controlling step (chemical or diffusion) were determined. With small particle size, the temperature dependence of reaction rate constant was determined and expressed by the Arrhenius equation, providing the apparent activation energy and the pre-exponential factor. The experiments were extended to larger particle size and the temperature dependence of the reaction rate constant was analysed.
96104147 Laboratory studies on devolatilization and char oxidation under PFBC conditions. 1. Volatile release and char reactivity Lu, Y. E/iergy Fuels, 1996, 10, (2), 348-356. Discusses the characterization of solid fuels during devolatilization and semicoke oxidation under pressurized fluidized-bed combustion conditions in a laboratory-scale batch reactor under well-defined operating conditions.
Laboratory studies on devolatilization and char 96104146 oxidation under PFBC conditions. 2. Fuel nitrogen conversion to nitrogen oxides Lu, Y. &ergy fuels. 1996, 10, (2), 357-363. Discusses the fuel nitrogen release, its conversion to NO,, and semicoke oxidation, in pressurized fluidized-bed combustion in a well-controlled laboratory-scale batch reactor at the base operating conditions of 850”, 11 bars, 3% (vol./vol.) 0, concentration, and fluidization velocity 0.24 m/s, for 10 fuels ranging from high-volatile peat to relatively low-volatile coke.