In a rectangular fluidized bed combustor, the tracer gas is injected continuously into the bed from a point source at the center of the distributor plate. In this study, a general governing equation is formulated for ...In a rectangular fluidized bed combustor, the tracer gas is injected continuously into the bed from a point source at the center of the distributor plate. In this study, a general governing equation is formulated for tracer gas dispersion in the bed. An analytical solution is derived to estimate the dispersion coefficients, Dxand Dy, in a horizontal plane. The concentration profiles at different sampling heights with various gas velocities are plotted.Subsequently, to estimate the dispersion coefficients, surface fitting of the obtained analytical solution to the experimental data is performed. The dispersion coefficients obtained from this model are compared with those of a conventional model. Additionally, the effect of walls, bed height and gas injection rate on the dispersion coefficients in a horizontal plane is investigated, and the effect of distributor design on the dispersion coefficients in a horizontal plane is investigated with different tracer positions. It is found that Dxand Dyare nearly equivalent at a lower tracer gas ratio of the injected gas to the total gas flow rate. It is also demonstrated that the effect of bed height on Dxis minor. This model is also able to estimate the dispersion coefficients in the case of a multihorizontal nozzle distributor.展开更多
Since 1978, Brazil has invested into bio-fuels alternatives, especially ethanol from sugar-cane processing and that has increased the bagasse production, which requires proper destination and a potential use of such b...Since 1978, Brazil has invested into bio-fuels alternatives, especially ethanol from sugar-cane processing and that has increased the bagasse production, which requires proper destination and a potential use of such biomass is the gasification process. In the present study, a conceptual design of a gasification system to convert sugar cane bagasse into syngas is presented, which considers air as gasification agent in a flexible configuration of bubbling fluidized bed reactor operating from atmospheric pressure up to 2 MPa, providing a net power output （referred at gas cold conditions） of 3 MWt and 66 MWt, respectively. In this last case, the gas may be used not just as a fuel for gas turbines and internal combustion engines for power generation but also to feed Fischer-Tropsch processes. The optimized conceptual design of the gasifier is described here and was achieved using the CSFMB （Comprehensive Simulator of Fluidized and Moving Bed Equipment）. Simulations predicted the production of gas with high heating value as well stable operations at both conditions. The conceptual design would be followed by the detailed one and construction. Tests would be carried in the near future and would allow direct comparison between the calculated and experimental results.展开更多
基金The financial support from the Ministry of Science and Technology under Grant MOST 105-3113-E-033-001
文摘In a rectangular fluidized bed combustor, the tracer gas is injected continuously into the bed from a point source at the center of the distributor plate. In this study, a general governing equation is formulated for tracer gas dispersion in the bed. An analytical solution is derived to estimate the dispersion coefficients, Dxand Dy, in a horizontal plane. The concentration profiles at different sampling heights with various gas velocities are plotted.Subsequently, to estimate the dispersion coefficients, surface fitting of the obtained analytical solution to the experimental data is performed. The dispersion coefficients obtained from this model are compared with those of a conventional model. Additionally, the effect of walls, bed height and gas injection rate on the dispersion coefficients in a horizontal plane is investigated, and the effect of distributor design on the dispersion coefficients in a horizontal plane is investigated with different tracer positions. It is found that Dxand Dyare nearly equivalent at a lower tracer gas ratio of the injected gas to the total gas flow rate. It is also demonstrated that the effect of bed height on Dxis minor. This model is also able to estimate the dispersion coefficients in the case of a multihorizontal nozzle distributor.
文摘Since 1978, Brazil has invested into bio-fuels alternatives, especially ethanol from sugar-cane processing and that has increased the bagasse production, which requires proper destination and a potential use of such biomass is the gasification process. In the present study, a conceptual design of a gasification system to convert sugar cane bagasse into syngas is presented, which considers air as gasification agent in a flexible configuration of bubbling fluidized bed reactor operating from atmospheric pressure up to 2 MPa, providing a net power output （referred at gas cold conditions） of 3 MWt and 66 MWt, respectively. In this last case, the gas may be used not just as a fuel for gas turbines and internal combustion engines for power generation but also to feed Fischer-Tropsch processes. The optimized conceptual design of the gasifier is described here and was achieved using the CSFMB （Comprehensive Simulator of Fluidized and Moving Bed Equipment）. Simulations predicted the production of gas with high heating value as well stable operations at both conditions. The conceptual design would be followed by the detailed one and construction. Tests would be carried in the near future and would allow direct comparison between the calculated and experimental results.
