Research And Application Of Gas-solid Two Phase Flow In 6000T/D Cyclone Preheater

With the decline of cement industry,domestic cement enterprises are facing transformation and market transfer.At present,the market focus of large domestic cement enterprises has been extended to foreign countries,especially in Africa and other areas where the cement industry is relatively backward.At the same time,the numerical simulation technology is used in the design and production of cement production line,which can improve the quality of cement production line and increase the competitiveness of products.On the basis of the numerical simulation technology and the engineering practice data,this paper took the Algeria 6000T/D five stage cyclone preheating system as the object,and established a complete and effective solution method,which can fully understand and analyze the flow field of gas solid two-phase flow in the cyclone preheater.This work guided the practice of engineering design and industrial production preheating system in a better way.Firstly,three kinds of gas solid two-phase flow model in cyclone separator were analyzed and discussed,which are DPM one-way coupling model,multiphase flow model and CFD-DEM coupling model.The flow field and dust collection efficiency of C1 cyclone were simulated and analyzed by using the DPM one-way coupled model and the multiphase flow model,then compared with the actual data.The results show that when the output of the preheater system is too large,the volume fraction of secondary phase in the local computational domain may exceed 10%,which leads to a large error in the DPM model,and the multiphase flow model is more suitable.Secondly,The five stage preheater system is analyzed.The results show that the pressure field,velocity field,dust collection efficiency,pressure loss and outlet temperature were all in good agreement with the actual situation." Partial flow " and "partial temperature" phenomenon occurred in the two cyclone of C1 stage,the reason is that the heat transfer between gas and solid does not reach the heat balance in the heat exchanger,so high temperature air flow and low temperature flow appears polarization under the influence of the whirlwind.The solution to remove " Partial flow " and "partial temperature" phenomenon was suggested.To install a flow control equipment in the outlet of C2 cyclone to reduce the curl of air flow.Then,heat transfer efficiency was improved so that it can be applied to the non adiabatic condition of cyclone preheater calculation on the basis of predecessors.Lastly,the key structure and parameters of cyclone were analyzed in this paper.It mainly included the bottom angle of the feeding hopper,the C1 return cone and the system wind speed.The conclusions were as follows: The heat transfer effect is best when the bottom angle is 15 degrees;The return air cone can improve the dust collection efficiency of the C1 cyclone,and the original radius and the installation height are appropriate;changing the radius or adjusting the height of the return air cone will result in the reduction of dust collection efficiency;The wind speed of the system is more suitable between 17m/s-19m/s,increasing wind speed will increase the pressure loss,the dust collection efficiency increases first and then decreases due to the gradual increase of the local vortex and the collision between the particles and the wall.