Study On Using Swirl Plate For Fine Catalyst Powder Classification

Due to the lack of rotating parts,the centrifugal static classifier is suitable for the working environment of high temperature and high pressure.It can classify FCC catalyst under hot conditions,thus to reduce the technological process and improve the efficiency.However,at present,the static classifier has many problems,such as poor classification accuracy and unsatisfactory classification effect,which makes it not applied in the production of FCC catalyst in China.Based on the thermal classification of industrial catalytic cracking(FCC)hot catalyst,this paper proposes to use swirl plate to classify 20μm fine powder particles,and designs a swirl plate classifier.Taking FCC catalyst as experimental material,the classification effects of the classifier and vertical dynamic classifier are compared through classification experiments,and the coupling relationship between the structural factors of the swirl plate classifier on the classification effect is analyzed by response surface method.At the same time,the flow field of the swirl plate classifier is studied and improved by using the numerical simulation method,and the calculation formula of cutting particle size is established,which provides a certain basic support for its design and optimization.The main contents include:(1)the experimental device is designed according to the existing swirl plate design method.Through the experiments,the influence laws of five parameters on the classification performance of the swirl plate classifier are investigated,including the separation height,the distance from the steady flow column to the top of the inner cylinder,the distance from the steady flow column to the exhaust pipe,the loading wind speed and the secondary wind speed.The coarse powder yield is further improved through the insertion depth of the exhaust pipe.The best experimental result is that the coarse powder yield is 89.97%,the content of particles below 20μm in coarse powder is 2.72%;(2)The influence degree of three structural factors on the classification performance is analyzed by using the response surface method: the separation height,the distance from the steady flow column to the top of the inner cylinder and the distance from the steady flow column to the exhaust pipe.The distance from the steady flow column to the exhaust pipe has the greatest influence on the classification performance and the separation height has the least influence;(3)The influence of the top tangential feed and side wall gravity feed on the classification performance of vertical dynamic classifier is investigated.Compared with the top tangential feed,the side wall gravity feed requires greater secondary air volume and has better classification effect.Compared with the best experimental results of swirl plate classifier,the classification effect is basically the same;(4)The flow field of swirl plate classifier is analyzed by numerical simulation,which further improves the irrationality of secondary air and coarse powder chamber,eliminates the adverse effects and regularizes the internal flow field;(5)Based on the equilibrium track theory,the calculation formula of cutting particle size is established.It is found that the loading wind volume and the distance between the steady flow column and the exhaust pipe in the experimental related parameters have a great impact on the classification effect in the mainstream field,which provides help for the subsequent design and improvement.