| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系 === 103 === Fluidized-bed reactors are widely used in many chemical industries and power plants, since they are characterized by the features of high efficiency, high heat transfer rates, low combustion temperature, low pollutant emissions, and less limitations on fuel selection. Combustion and gasification technology of pulverized coal in a fluidized-bed gasifier is thus an essential one for clean-coal technologies. In the present study, a numerical model for the simulation of combustion and gasification of pulverized coal in a bubbling fluidized-bed gasifier has been developed by using the commercial CFD software, ANSYS/ FLUENT. The Eulerian-Eulerian approach is employed for the gas-solid multiphase flow, where different phases are treated as interacting continua. The physical sub-models include the char oxidation model, the turbulent combustion model, and the thermal radiative model. The finite-rate and eddy-dissipation combustion models are employed for the gas combustion. A model-gasifier with a height of 200 cm and a diameter of 22 cm has been investigated by the present model. The bituminous coal, Colombia coal, is used as the feedstock in the study to verify with the reference data. For the parameter analyses, the Equivalence ratio(ER ratio) is conducted for evaluating the effect of coal gasification. The numerical results show that the outlet gas compositions predicted by the study are generally in agreement with the experiment data. In this model, CO2 is slightly underestimated and H2 is overestimated in the numerical model.
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