Numerical Simulation Of Pneumatic Conveying Of Solid Heat Carrier

Coal gasification is one of the main ways of coal using,which is clean and efficient utilization,also is the key technology and important part of many energy high-tech.The coal gasification and combustion process were carried out in different devices,and coal gasification process is not in direct contact with air,thus avoiding gasification generation gas was diluted by the nitrogen and the carbon dioxide,and to improve the calorific value of the gas.So this gasification way was called lignite gasification technology using coalite solid heat carrier,and the key of the gasification technology are heat generation and transmission.Lignite gasification technology using coalite solid heat carrier was taking the coalite in the dense phase from riser where heating itself and transported to the gasifier by pneumatic conveying.Most study on dense-phase pneumatic conveying are based on experimental researches,due to the restrict of the experimental condition.so it is hard to get the details of gas-soild two-phase flow. Along with the computational fluid dynamics application and development, using computer simulation technology can get the flow field information of gas-solid two-phase flow,and can be adjustment the parameters of the design proposal in a short time,so as to guide practical production.In this thesis, take the vertical riser of ignite gasification technology using coalite solid heat carrier as research object,and numerical simulation the coalite of suspension pneumatic conveying in the riser by FLUENT.A two-phases flow model is established based on granular kinetic theory to multiphase flow in pneumatic conveying process. In this modle,the ineraction between gas-solid particle-particle collision and particle-wall collision are considered.By means of simulating different air speed and different particle density in vertical pneumatic conveying of the riser,the mean gas-solid velocity,the particle volume fraction distributions and pressure drop can get.For the different air speed,the simulation results show that the faster the air is,the bigger core-annular flow frame is ,meanwhile,the backflow area above the inlet of solids becomes smaller.For the different solid density,simulation results show that the bigger the density is,the bigger the preesure drop is,meanwhile,the concentration distribution more uniform of the solid above the inlet of solids.