Study On Mass Transfer Of Fluidized Bed Coal Gasifier

With the extensive application of fluidized bed gasifier,the study about its mass and heat transfer process is also deepening.The mass transfer process is inseparable from the gas-solid two-phase flow.Due to the complex interaction between gas and solid phases,many scholars have carried out a lot of research on the gasifier mainly by numerical simulation,but they have not considered the effect of particle flow behavior and gasifier operating conditions on gasification performance insufficiently.In this paper,the fluidized bed gasifier is used as the research object,and the gas-solid mass transfer process of gasifier is studied by numerical simulation and the actual situation of the factory.Firstly,based on the actual situation of gasifier structure and gasification process,combined with the enterprise field data,the three-dimensional model of fluidized bed gasifier was constructed.And the model is validated by the literature data,the results show that the model is feasible.Secondly,the numerical simulation of the gasifier under the reference working condition is carried out.The results show that: In the jet area,most of the reaction between the oxidant and the pulverized coal particles has been completed.There is an impact stagnation at the center of the gasifier,and the velocity is close to zero at the station,but the turbulence is the highest.In the inlet level,the velocity of the fluid is higher,and on the sides of the inlet level the velocity is gradually reduced.The distribution of the synthesis gas is similar to the temperature distribution,all of which are on the edge of the jet region is very high and the center is low.After into the gasifier,most particles on the effect of airflow to carry into the return area,some particles directly into the bottom with the ash discharge or carry out by air.Finally,the gasifier was simulated by various working conditions,and the influence on gasification process was analyzed.The results show that: Increasing the oxidant flows and refined particles can improve the gasification performance,and can improve the effective gas production rate too.The optimum oxidant flow is 7.26 kg / s,and the optimum particle diameter is 30 um.To a certain extent,increasing the preheating temperature of pulverized coal will improve the gasification performance,however,the overall impact is not obvious.