Simulation Analysis And Structure Optimization Of Shell And Tube Heat Exchanger With Spiral Baffles

Shell and tube heat exchanger as a common heat exchange equipment plays an important role in the field of chemical industry.Improving the heat exchange performance of heat exchanger has far-reaching significance for energy saving and emission reduction in production.According to the requirements of Nantong Kessel Machinery Co.,Ltd.,the dn273 vertical shell and tube heat exchanger is designed to solve the problem of low shell side heat exchange efficiency.In this paper,the optimization and improvement of the baffle structure is taken as the design scheme to improve the heat transfer performance,and the original single bow baffle structure is proposed to be changed into a quarter type discontinuous spiral baffle structure.The influence mechanism of the baffle structure on the shell side flow and heat transfer characteristics is discussed by using the finite element numerical simulation method.Based on the analysis of the shell side fluid flow of single bow baffle,it is found that most of the shell side fluid has a large retention area due to the original structure of baffle,and the strengthening direction of shell side is clear.Combined with the structural characteristics of heat exchanger,the initial baffle structure is designed.The three-dimensional flow and heat transfer model of shell side of heat exchanger is established by using CFX software to simulate the influence of fluid flow on heat transfer performance after the baffle plate is initially improved.It is found that the triangular leakage area in shell side is not conducive to improving heat transfer performance and has a great influence,so it is necessary to continue to optimize the baffle plate structure for the triangular leakage area.The baffle was improved from single helix structure to double helix structure,and the baffle with double helix structure was placed at 60° dislocation.On this basis,the numerical simulation analysis of different double helix staggered baffle heat exchangers was carried out,focusing on the effects of baffle helix angle,thickness and total number on shell side pressure drop and heat transfer performance.Finally,the helix angle of baffles is 30° and the thickness of baffles is3 mm.The number of baffles is 16.Finally,based on the final design of baffle structure,the overall size and parts of the heat exchanger are improved,and the finite element software simulation analysis shows that the improved structure meets the working requirements of the heat exchanger,that is,the tube side gas is heated from 120℃ to 140℃.According to the statistics of the heat exchanger parameters before and after the improvement,the total mass was reduced by 64.5kg,the manufacturing cost of the heat exchanger is reduced,and the utilization rate of resources is improved.