Numerical Simulation And Optimal Design Of Medium-High Temperature Air Preheater

The air preheater is one of the key equipments for industrial production.It is used to preheat the air into the furnace.The preheated air is sent to the reactor for combustion,which not only improves the product yield,but also makes the energy of the enterprise.The cost is greatly reduced.According to the demand of a company’s carbon black production line,a 400 °C medium and high temperature tube-type air preheater is designed by theoretical calculation,and then the structure is optimized by Fluent.The main contents are as follows:(1)In the selection of research methods for air preheaters,due to the complexity of fluid flow and heat transfer in the shell-and-tube heat exchanger,the theoretical method cannot meet the actual engineering requirements,and the cost of experimental research is too high.It is a numerical simulation,so this paper mainly uses a combination of theoretical calculation and numerical simulation.(2)In the theoretical calculation of the air preheater,this paper briefly introduces the basic structure of the shell-and-tube heat exchanger and the commonly used process calculation method,and then determines the appropriate process calculation method according to the actual pressure drop and heat transfer requirements.The main structural parameters of the heat exchanger,and finally the use of Solidworks to build a three-dimensional model.At the same time,the flow-heat coupling analysis of the air preheater process was carried out.(3)In the numerical simulation of the air preheater,the flow heat coupling simulation of the established heat exchanger model is firstly carried out by Fluent,and the deviation between the obtained result and the theoretical calculation result is about 20%,which can roughly meet the engineering requirements.Fluent is used to optimize the structure of the air preheater shell to obtain the air preheater with the best heat transfer performance.Here,the ratio of the total heat transfer coefficient to the pressure drop of the air preheater is selected as the criterion.The results show that: 1 the heat transfer performance of the single bow baffle air preheater is stronger than that of the double bow and the reinforced baffle;2 when the baffle gap height is 0.3D,the number of baffles is 10.The air preheater has the best heat transfer performance.3 When the baffle number is 12,the air preheater performance of the baffle with a notch height of 0.3D is the best.