Experimental Study On Gas-solid Separation In Axially Moving Bed With Gas-solid Concurrent Flow

At present,with the wide use of the fossil fuels,the environment is seriously polluted.In industrial area,a mass of fine dust particles which is harmful to the atmosphere are generated due to insufficient combustion of fossil fuels.In order to effectively control the emission of fine particles and realize the purpose of flue gas purification,this paper attempts to use a gas-solid parallel flow axial moving bed separation system to achieve this goal.Firstly,a set of large-scale cold model experimental setup for gas-solid parallel flow axial moving bed gas-solid separation system was designed and built;and then the dust-free and dust loading experiments were carried out for two kinds of particles with different particle sizes.Under the condition of dust-free load（the so called pure moving bed operation）,the influence of superficial gas velocity and particle moving velocity on the pressure drop of moving bed was investigated.The radial distribution and axial distribution of the pressure in the particle bed were measured.Based on the characteristics of gas-solid two-phase movement in moving bed,Ergun formula is modified to calculate the pressure drop of axial moving bed more accurately.The residence time distribution of gas in the equipment under different operating conditions was also analyzed.Under the dust loading operating,the effects of the physical properties（mainly the particle size）,the superficial gas velocity,the gas dust inlet concentration,the particle movement rate and other operating parameters on the pressure drop and collection efficiency of the equipment were investigated.Comparing the two kinds of capture particles with different physical properties,it is found that the particle size distribution and the voidage between particles have great influence on the pressure drop and trapping efficiency.In the moving bed filter,the larger the voidage between particles,the lower the pressure drop of the equipment is.On the contrary,the smaller the voidage between particles,the greater the pressure-drop of the equipment presents.The experimental results show that under our investigated experimental operating conditions,the filter material particles shall adopt the small-size trapping particles;and the axial moving bed filter has higher dust trapping efficiency.A parameter named by the specific deposition rate is introduced to describe the deposition ratio of dust in the bed.It is found that the specific deposition rateσhas a great influence on the bed pressure drop and the collection efficiency.When the specific deposition rateσis in the range of 5.84×10^-4～7.35×10^-4,the pressure drop of the equipment can be kept stable for a long operating period and the collection efficiency of dust is high.Under our investigated operating conditions,if the specific deposition rate deviated from the range,the trapping efficiency of the equipment would be decreased.In a word,the gas-solid parallel flow axial moving bed filter has better gas-solid flow characteristics while the equipment has stable operation pressure drop/higher trapping efficiency in the suitable operating range.