Study On O-SEPA Classifier's Structure And Its Fluid Field Characteristics

Air classifier is one of the important equipments used in powder industrial production, which experienced three generations, with centrifugal air classifier,whirlwind air classifier and turbo air classifier as the first,second and third generation classifiers, respectively.Classifier makes the particle size suit to the demand of powder product through classification.It has been widely used in many fields, such as cement industry,materials industry, electricity power, materials, mineral processing industry, chemical industry, pharmaceutical industry, food industry and so on.With the implementation of the new cement standard in our country,the requirement of the cement is becoming higher and higher, such as small diameters and narrow size distributions, etc, which put forward higher requirement for classification equipment.As the typical representative of the turbo air classifier,O-SEPA classifier has the following features:low maintenance,simple layout,high classification precision,good classification performance,high-efficiency separation.O-SEPA classifier which is applied in the close-circuit mill system is one of the most important equipments of the cement industry.O-SEPA classifier can remove the expected fine powder from the materials discharged from grinding mill timely ,and return the coarse powder back to the grinding mill,which avoids the fine particles staying in grinding mill too long time as well as being overpulverized and adhering the coarse particles to grinding balls.Thus it could increase the efficiency and output of grinding system effectively. What is more,it also can improve the production efficiency, reduce the energy consumption and control the product size.The flow field of O-SEPA classifier is very complicated,its distribution determines the trajectory of particles, and also the performance of classifier. While the cage rotor as the key component part of the classifier and its structure and process parameters have the important role on the flow field characteristics and performence of classifier. Thus, in order to improve performance of classifier, we must learn a lot about the structure and process parameters of cage rotor.In this paper,the structure and flow field characteristics of classifier in full scale are simulated and studied based on CFD Code commercial software FLUENT6.3. First, The three-dimensional flow field characteristics of the O-SEPA classifier were simulated under different operating conditions, thus obtaining the more objective and detailed flow characteristics of classifier, as a reference for the design and research in the future. Secondly, simulating the effects caused by rotational speed of cage on flow field characteristics and performance of classifier, the simulation results show that although improving the speed can significantly improve the classification precision, however the high speed will lead to flow field instability, as well as the increase of pressure drop of classifier, and finally affect its performance .Thirdly, four O-SEPA classifier models with different type bottom plates are analyzed and simulated. The result shows that bottom plate structure can influence the flow field characteristics and performance of classifier to a certain extent.