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Pressurized drop tube furnace test of global coal gasification characteristics
11 00100528
Polyaromatic environmental impact in coal-tire blend atmospheric fluidized bed (AFB) combustion
Mastral, A. M.-e! al. Energy Fuels, 2006, 14,-(l), 164-168. This paper describes how for the first time the use of a waste material can be combined with trying to get cheaper power with a lower consumption of fossil fuel. A coal-tire blend (I:1 in organic matter) was burned in an atmosoheric fluidized bed (AFB) combustion olant with an airflow of 860 ‘L/h and 20% excess oxygen at three’ different combustion temperatures. (750, 850, and 950°C). The combustion conditions were-the same as those used in AFB coal combustion in order to compare the organic emissions obtained with both fuels. As the inorganic components in tires are less and in lower amounts than in coal, the work was focused on organic emissions. Organic emissions from each run were trapped and from each sample, after extraction by sonication with DMF (DMF), the content in polycyclic aromatic hydrocarbons (PAH) was detected by fluorescence-spectroscopy in the synchronous mode (FS). It is concluded that the introduction of tyres in the feeder increases the total PAH amount emitted with respect to coal emissions, with minimal variations at the combustion temperature studied in this work: thus, the higher the temperature, the lower the amount of emitted polycyclic aromatic hydrocarbons.
00100529 Pressurized drop tube furnace test of global coal aasification characteristics chin, Y. et al. Inr. J. Energy Res., 2000, 24, (9) 749-758. Pressurized drop tube furnace (PDTF) tests were performed with an Indonesian sub-bituminous coal while .temperature; oxygen/coal ratio, steam/coal ratio and pressure were systematically varied. The tests were desiened to investieate the effects of these exoerimental parameter; on the pulvehzed coal gasification characteristics at elevated pressure. The results showed that the gasification at elevated pressure -is more productive than that at atmospheric pressure, considering the carbon conversion and cold gas efficiency. The oxygen/coal ratio at the maximum cold gas efficiency ranged between 0.5 and 0.7 g/g. Only when the temperature was sufficiently high, did the increase of steam/coal ratio result in the improvement of cold gas efficiency. As the pressure increased, the contribution of carbon conversion by heterogeneous reactions increased while the conversion by pyrolysis decreased. 00/00530 Reactors with circulating fluldized bed Hartman, M. et al. Chem. Listy, 1999, 93, (12), 788-793. (In Czech) In circulating fluidized beds, a gas stream is used to transport the fine particles upwards and then they are recycled to the bottom of the column. The flow structure is complex and varies widely depending mainly on the vessel geometry, _gas velocity and particle size distribution. Unlike the bubbled bed, the entrv. exit and wall configurations have a strong effect on the flow and mixing patterns of both phases in the column. The tendency is for small particles to form larger, irregular aggregates, which disintegrate and form again at appreciable frequencies. Simple core-annulus models for circulating fluidized beds assume the up-flow of gas and entrained solids in a diluted central core and the down-flow of dense clusters in a relatively thin annular zone near the walls. Rapid heat and mass transfer between gas and particulate solids, uniform temperature in the whole CFB, virtually a plug flow of gas and possible stepwise addition of one or more gaseous components at different levels are among the main features of the CFB reactors. The most rapidly expanding field of CFB application is the efficient combustion and pressure gasification of carbon containing residues, in particular fossil fuels. 00100531
Solid circulation and as bypassing in spoutfluidized bed with draft tube at e9evated pressure
Xiao, R. et al. Ranliao Huaxue Xuebao. 1999. 27, (4). 370-376. (In Chinese) An experimental study on solid circulation and gas bypassing of spoutfluidized bed with draft tube at elevated pressure was performed in a 20 cm diameter cylindrical column with a 600 conical distributor. For bed material, glass beads with a mean diameter of 2.0 mm were used. A new method was develooed for measurine solid circulation under pressure and a gas (CO; tracers) were employed to investigate the characteristics of the gas bypassing. The solid circulation and gas bypassing were strongly dependent bn each other and influenced-by geometric parameters and operation conditions. For predicting solid circulation in a spout-fluidized bed with draft tube at elevated pressure an experimental correlation was proposed.
Stackable heat exchanger for processing carbonaceous material
00/00532
Koppelman, E. PCT Int. Appl. WO 99 50,609 (Cl. F28F9/26), 7 Ott 1999, US Appl. 50,393, 30 Mar 1998. 23. The present invention relates to a heat exchanger apparatus including a plurality of selectively detachable cells to accommodate the treatment of carbonaceous material, such as wood, peat or subbituminous coal, in
Process
heating,
power
and
incineration
(energy
applications
in industry)
varying amounts. The invention also relates to systems and processes for mineral removal from the carbonaceous materials and thereafter upgrading the carbonaceous material for use as fuel. 00100533
Study of the adsorption of CdClz vapor on various minerals using a drop tube furnace
Masseron. R. et al. Environ. Sci. Technol.. 1999. 33. (201. 3634-3640. Fixed bed’or thermogravimetric apparatus were’used’to’perform most of these studies and it is often difficult to correlate the results of these experiments with incineration flue gas conditions. To analyse the reaction between heavy metal vapour and suspended particles more accuratelv. the GRE laboratorv has develooed a droo tube furnace. With this’ experimental set-up, it was possible d quantify the adsorption of cadmium chloride on different sorbents in conditions representative of incinerators; a dilution stream of particles was in contact with a counter current flow of metal vaoours at hieh temperature during a few seconds. Leaching was done&to quantify tYhe physical sorbed and chemisorbed fractions of the metal. Silica, alumina, alumina-silica, and calcium oxide were utilized and the influence of sorbent surface area, gas temperature and metal vapour concentration was investigated. Alumina and calcium oxide were found to be more effective for cadmium capture. The leachable fraction of cadmium on each sorbent appears to be very low. This is in favour of a chemisorption mechanism. In order to obtain characteristic values of vapour chemisorption on these sorbents, the results of the study were correlated with Freundlich isotherms.
Thermal analysis of a fluidized bed drying process for crops. Part I: mathematical modeling
00100534
Hajidavalloo, E. and Hamdullahpur, F. Inr. J Energy Res., 2000, 24, (9), 791-807. Development of a comprehensive mathematical model to simulate the simultaneous heat and mass transfer processes in a bubbling fluidized bed is described. Although the model is applicable to a wide range of particles, wheat is chosen as an example. In the development of the model, the commonly used two-phase theory is not used because of its insensitivity to the particle group used in the bed. Instead, a new hydrodynamic model is developed for each specific particle group. The behaviour of bubbles in a bed of group D particles (wheat) is modelled with the consideration that they grow in size as they rise in the bed, but are of the same size at any height in the bed. The voidage of bubbles, particles and interstitial gas is modelled separately. A newly developed expression to determine the minimum fluidization velocity of wet particles is used. The model considers the presence of different phases inside the bed and their physical variation along the bed. The interstitial gas phase, the bubble phase and the solid phase are modelled separately. The drying mechanism for the solid phase is considered in two stages: the falling rate and the constant rate, with appropriate temperature and moisture diffusion coefficients and wall effects. The simultaneous heat and mass transfer processes during the drying process including the internal and external effects are modelled for each phase. A set of coupled non-linear partial differential equations is employed to accurately model the drying process without using any adjustable parameters. A numerical code is developed to solve the governing partial differential equations using a control volume-based discretization approach. Piecewise profiles expressing the variation of dependent variables between the grid points are used to evaluate the required integrals. 00/00535
Thermal analysis of a fluidized bed drying process for crops. Part II: experimental results and model verification
Hajidavalloo, E. and Hamdullahpur, F. Inr. J. Energy Res., 2000, 24, (9) 809-820. An experimental investigation was undertaken to provide key data for the drying of wheat, and to assess the validity of the mathematical model described in Part I, and test its accuracy. The results of numerical solutions are compared with experimental data for wheat grains. Wheat is one of the main agricultural products and has extensive application in drying systems and therefore the accuracy of results for this product is of primary concern. Furthermore, as the desorption isotherms of wheat material are well documented, it is possible to accurately simulate the drying processes. Wheat belongs to the hygroscopic materials group and has a very low-mass diffusivity. Usually, no constant rate period is observed in the course of drying of wheat in the moderate range of initial moisture content, and drying takes place in the falling rate mode. In this study, it was confirmed that immediately after the particles are exposed to the drying medium, the surface moisture of material transfers rapidly due to low external resistance to heat and mass transfer. However, later on the moisture removal rate decreases noticeably with time because of the high internal resistance to diffusion. In the experiments, temperature at different elevations, humidity of the exit air, bed pressure drop, fluidization velocity and moisture content of particles at different times are measured. Each experiment is repeated at three inlet air Fuel and Energy Abstracts
January 2001
55
Polyaromatic environmental impact in coal-tire blend atmospheric fluidized bed (AFB) combustion
Mastral, A. M.-e! al. Energy Fuels, 2006, 14,-(l), 164-168. This paper describes how for the first time the use of a waste material can be combined with trying to get cheaper power with a lower consumption of fossil fuel. A coal-tire blend (I:1 in organic matter) was burned in an atmosoheric fluidized bed (AFB) combustion olant with an airflow of 860 ‘L/h and 20% excess oxygen at three’ different combustion temperatures. (750, 850, and 950°C). The combustion conditions were-the same as those used in AFB coal combustion in order to compare the organic emissions obtained with both fuels. As the inorganic components in tires are less and in lower amounts than in coal, the work was focused on organic emissions. Organic emissions from each run were trapped and from each sample, after extraction by sonication with DMF (DMF), the content in polycyclic aromatic hydrocarbons (PAH) was detected by fluorescence-spectroscopy in the synchronous mode (FS). It is concluded that the introduction of tyres in the feeder increases the total PAH amount emitted with respect to coal emissions, with minimal variations at the combustion temperature studied in this work: thus, the higher the temperature, the lower the amount of emitted polycyclic aromatic hydrocarbons.
00100529 Pressurized drop tube furnace test of global coal aasification characteristics chin, Y. et al. Inr. J. Energy Res., 2000, 24, (9) 749-758. Pressurized drop tube furnace (PDTF) tests were performed with an Indonesian sub-bituminous coal while .temperature; oxygen/coal ratio, steam/coal ratio and pressure were systematically varied. The tests were desiened to investieate the effects of these exoerimental parameter; on the pulvehzed coal gasification characteristics at elevated pressure. The results showed that the gasification at elevated pressure -is more productive than that at atmospheric pressure, considering the carbon conversion and cold gas efficiency. The oxygen/coal ratio at the maximum cold gas efficiency ranged between 0.5 and 0.7 g/g. Only when the temperature was sufficiently high, did the increase of steam/coal ratio result in the improvement of cold gas efficiency. As the pressure increased, the contribution of carbon conversion by heterogeneous reactions increased while the conversion by pyrolysis decreased. 00/00530 Reactors with circulating fluldized bed Hartman, M. et al. Chem. Listy, 1999, 93, (12), 788-793. (In Czech) In circulating fluidized beds, a gas stream is used to transport the fine particles upwards and then they are recycled to the bottom of the column. The flow structure is complex and varies widely depending mainly on the vessel geometry, _gas velocity and particle size distribution. Unlike the bubbled bed, the entrv. exit and wall configurations have a strong effect on the flow and mixing patterns of both phases in the column. The tendency is for small particles to form larger, irregular aggregates, which disintegrate and form again at appreciable frequencies. Simple core-annulus models for circulating fluidized beds assume the up-flow of gas and entrained solids in a diluted central core and the down-flow of dense clusters in a relatively thin annular zone near the walls. Rapid heat and mass transfer between gas and particulate solids, uniform temperature in the whole CFB, virtually a plug flow of gas and possible stepwise addition of one or more gaseous components at different levels are among the main features of the CFB reactors. The most rapidly expanding field of CFB application is the efficient combustion and pressure gasification of carbon containing residues, in particular fossil fuels. 00100531
Solid circulation and as bypassing in spoutfluidized bed with draft tube at e9evated pressure
Xiao, R. et al. Ranliao Huaxue Xuebao. 1999. 27, (4). 370-376. (In Chinese) An experimental study on solid circulation and gas bypassing of spoutfluidized bed with draft tube at elevated pressure was performed in a 20 cm diameter cylindrical column with a 600 conical distributor. For bed material, glass beads with a mean diameter of 2.0 mm were used. A new method was develooed for measurine solid circulation under pressure and a gas (CO; tracers) were employed to investigate the characteristics of the gas bypassing. The solid circulation and gas bypassing were strongly dependent bn each other and influenced-by geometric parameters and operation conditions. For predicting solid circulation in a spout-fluidized bed with draft tube at elevated pressure an experimental correlation was proposed.
Stackable heat exchanger for processing carbonaceous material
00/00532
Koppelman, E. PCT Int. Appl. WO 99 50,609 (Cl. F28F9/26), 7 Ott 1999, US Appl. 50,393, 30 Mar 1998. 23. The present invention relates to a heat exchanger apparatus including a plurality of selectively detachable cells to accommodate the treatment of carbonaceous material, such as wood, peat or subbituminous coal, in
Process
heating,
power
and
incineration
(energy
applications
in industry)
varying amounts. The invention also relates to systems and processes for mineral removal from the carbonaceous materials and thereafter upgrading the carbonaceous material for use as fuel. 00100533
Study of the adsorption of CdClz vapor on various minerals using a drop tube furnace
Masseron. R. et al. Environ. Sci. Technol.. 1999. 33. (201. 3634-3640. Fixed bed’or thermogravimetric apparatus were’used’to’perform most of these studies and it is often difficult to correlate the results of these experiments with incineration flue gas conditions. To analyse the reaction between heavy metal vapour and suspended particles more accuratelv. the GRE laboratorv has develooed a droo tube furnace. With this’ experimental set-up, it was possible d quantify the adsorption of cadmium chloride on different sorbents in conditions representative of incinerators; a dilution stream of particles was in contact with a counter current flow of metal vaoours at hieh temperature during a few seconds. Leaching was done&to quantify tYhe physical sorbed and chemisorbed fractions of the metal. Silica, alumina, alumina-silica, and calcium oxide were utilized and the influence of sorbent surface area, gas temperature and metal vapour concentration was investigated. Alumina and calcium oxide were found to be more effective for cadmium capture. The leachable fraction of cadmium on each sorbent appears to be very low. This is in favour of a chemisorption mechanism. In order to obtain characteristic values of vapour chemisorption on these sorbents, the results of the study were correlated with Freundlich isotherms.
Thermal analysis of a fluidized bed drying process for crops. Part I: mathematical modeling
00100534
Hajidavalloo, E. and Hamdullahpur, F. Inr. J Energy Res., 2000, 24, (9), 791-807. Development of a comprehensive mathematical model to simulate the simultaneous heat and mass transfer processes in a bubbling fluidized bed is described. Although the model is applicable to a wide range of particles, wheat is chosen as an example. In the development of the model, the commonly used two-phase theory is not used because of its insensitivity to the particle group used in the bed. Instead, a new hydrodynamic model is developed for each specific particle group. The behaviour of bubbles in a bed of group D particles (wheat) is modelled with the consideration that they grow in size as they rise in the bed, but are of the same size at any height in the bed. The voidage of bubbles, particles and interstitial gas is modelled separately. A newly developed expression to determine the minimum fluidization velocity of wet particles is used. The model considers the presence of different phases inside the bed and their physical variation along the bed. The interstitial gas phase, the bubble phase and the solid phase are modelled separately. The drying mechanism for the solid phase is considered in two stages: the falling rate and the constant rate, with appropriate temperature and moisture diffusion coefficients and wall effects. The simultaneous heat and mass transfer processes during the drying process including the internal and external effects are modelled for each phase. A set of coupled non-linear partial differential equations is employed to accurately model the drying process without using any adjustable parameters. A numerical code is developed to solve the governing partial differential equations using a control volume-based discretization approach. Piecewise profiles expressing the variation of dependent variables between the grid points are used to evaluate the required integrals. 00/00535
Thermal analysis of a fluidized bed drying process for crops. Part II: experimental results and model verification
Hajidavalloo, E. and Hamdullahpur, F. Inr. J. Energy Res., 2000, 24, (9) 809-820. An experimental investigation was undertaken to provide key data for the drying of wheat, and to assess the validity of the mathematical model described in Part I, and test its accuracy. The results of numerical solutions are compared with experimental data for wheat grains. Wheat is one of the main agricultural products and has extensive application in drying systems and therefore the accuracy of results for this product is of primary concern. Furthermore, as the desorption isotherms of wheat material are well documented, it is possible to accurately simulate the drying processes. Wheat belongs to the hygroscopic materials group and has a very low-mass diffusivity. Usually, no constant rate period is observed in the course of drying of wheat in the moderate range of initial moisture content, and drying takes place in the falling rate mode. In this study, it was confirmed that immediately after the particles are exposed to the drying medium, the surface moisture of material transfers rapidly due to low external resistance to heat and mass transfer. However, later on the moisture removal rate decreases noticeably with time because of the high internal resistance to diffusion. In the experiments, temperature at different elevations, humidity of the exit air, bed pressure drop, fluidization velocity and moisture content of particles at different times are measured. Each experiment is repeated at three inlet air Fuel and Energy Abstracts
January 2001
55