Simulation Of Cold Flow Field And Combustion Processes In The Y-Type Coal-Water Slurry Gasifier

Air-bed coal gasification technology represents the development trend of coal gasification technology, and coal-water slurry gasification is a typical air-bed gasification technology. Gasifier is the core and key equipment of coal-water slurry gasification technology, and the flow field distribution, concentration distribution of material as well as the residence time in gasifier have a direct impact on the combustion efficiency and conversion rate of coal-water slurry of gasifier.Including furnace systems, coal-water slurry feed system, gasification agent feed system, quench system, slag-off system, cooling water system, as well as gas analysis system, and the overall process has been designed. At the same time the various types of nozzle characteristics are also discussed. In this paper, simulation and calculation of fluid dynamics and combustion chemical reaction was done for Y-type coal-water slurry gasifier, which designed by the Mineral Processing Laboratory of University of Science and Technology of Shan Dong. The 3D model of gasification chamber was established with the use of the pre-processing software, Gambit2.2.30, which is in application for CFD (Computational Fluid Dynamics), And numerical simulation and calculation and analysis of cold flow and combustion process of the furnace were done with the use of CFD commercial software, Fluent6.3.26. The distribution of flow field of gas turbulence of coal-water slurry gasifier was simulated by selecting standard k-εturbulent flow model and SIMPLE algorithm. The numerical simulation of CH4 turbulent combustion in the three-dimensional space was done by selecting component transmission equation and eddy dissipation model. PDF inquiry form of non-adiabatic gasification of coal-water slurry was gotten by using two mixture fraction method of non-premixed method.By analyzing the simulation results and comparing flow partitioned of gasifier, the result was obtained that the distribution of flow field of furnace was more rational when feed gas velocity of top nozzle and side nozzle of gasifier was different. The turbulent flow in furnace is more intense, and more return flow space in the furnace. The distributions of temperature field and material concentration of gasifier were obtained by simulation calculating. From the side nozzle of the furnace to the top nozzle, the peak temperature of every cross-section reduces after the first increase. The highest temperature appears near the nozzle. For the impact of different reaction mechanism, the mole fraction of product is different from stoichiometric. Comparing the reaction results using gasifying agent of different oxygen content, the result was obtained that instantaneous high temperature of furnace was directly related to O2 content of the gasification agent, and when O2 content was larger, the peak of instantaneous temperature was higher and the concentration distribution of product was different. The result of concentration distribution of product was in better line with the actual situation of industry by analyzing product concentration in inquiry form, which had laid a good foundation for further calculating gasification reaction process.