Numerical Simulation And Structural Optimization Of Steel Heat-conducting Oil-drying Cylinder

A paper-making machinery enterprise manufactures a large steel heat-conducting oil dryer.According to the test and customer use,it reflects the uneven temperature distribution on the surface of the steel heat-conducting oil dryer,resulting in the temperature difference of the dryer’s working surface not reaching the ideal papermaking process requirements.Therefore,this paper uses 3D modeling software and finite element analysis software to optimize the structure of the steel heat conduction oil dryer.The specific research contents are as follows:(1)By analyzing the working principle and heat transfer principle of the steel heat conduction oil dryer,the theoretical basis for optimizing the dryer structure is proposed.The optimization work of the dryer structure mainly includes: the change of the oil storage cavity structure,the oil inlet and outlet oil storage cavity attached to the inner wall of the dryer are removed,so that the heat conduction oil directly enters the oil guide cavity of the dryer;metal The change in the structure and quantity of the tube converts the straight metal tube of the dryer into a curved tube,and increases the number of metal tubes;the change in the structure and quantity of the oil circuit directly connects the metal tube and the oil guide cavity,so at the same time increasing the number of metal tubes It will increase the number of oil passages.The oil passage structure of the original dryer is in a single flow direction.The oil passage structure is optimized into a circulating flow direction through the use of metal bends,and the circulating oil passages are divided into single "S" type and "S" "Two types of structure;hydraulic diameter size change;oil guide cavity height change,increase the height of the oil guide cavity of the dryer to increase the contact area of the heat transfer oil and the dryer,improve heat transfer efficiency;change the thickness of the outer wall.The optimized steel heat-conducting oil dryer adopts modeling software to establish its three-dimensional model.(2)According to the working principle and heat transfer principle of the steel heat conduction oil dryer,mathematical equations are established.The numerical simulation method is used to simulate the thermal fluid-solid coupling model of the steel heat conduction oil dryer.The model is divided into multiple unstructured grids.The grid independence verification method is used to select a model with a moderate number of grids.Then,the Dittus-Boelter experimental correlation with Nusselt number as the objective function is used to verify the dryer numerical simulation.As a result,this verification method can confirm the correctness of the choice of solver,the choice of physical model and the establishment of boundary conditions in the simulation process.(3)Carry out numerical simulation on the optimized steel heat conduction oil dryer respectively,read Reynolds number,dryer working pressure,surface heat transfer coefficient,average temperature data on the working surface,and derive a cloud map of the working surface temperature distribution of the dryer.The analysis results show that: Reynolds number,dryer working pressure and heat transfer coefficient decrease with the increase of the number of metal pipes and oil passages;the average surface temperature of the dryer increases with the increase of hydraulic diameter,and the wall thickness of the dryer Increase and decrease.From the temperature distribution cloud diagram,it can be seen that the temperature distribution of the dryer surface of the circulating oil circuit structure is ideal.Therefore,a dryer structure with a circulating oil circuit is selected.By changing the inlet speed of the thermal oil and performing a numerical simulation,the results show that as the inlet speed increases,the temperature difference between the outer wall surface of the dryer and the working surface temperature decreases,and the temperature distribution It can be seen from the cloud image that the temperature distribution on the outer wall surface of the dryer cylinder with a number of 32 metal tubes and a double "S" type circulating oil path structure is uniform.(4)The experimental test of the optimized new dryer is carried out.The results show that the maximum error between the experimental test results and the numerical simulation results is 3.36%,which is within the allowable range.Customers have also been verified with good results in the trial operation and production process of the new steel heat conduction oil dryer group.