Research And Application Of Distillation Column Simulation Initialization Algorithm

The rigorous distillation calculation is to solve the process by listing the MESH equation of the entire distillation process and then using the iterative method to solve the highly nonlinear equations,and an excellent initial value is of great significance for the convergence of the equations.Therefore,this paper systematically studies the initialization of the distillation process simulation and proposes two initialization methods.Firstly,to give the initial value of the vapor-liquid flow distribution along the tray,considering the influence of temperature on the evaporation enthalpy of the components,the constant heat transport model of Endre is improved.From the distillation process model,the constant heat transport model is spread to the complex distillation process.For the initialization of temperature and composition,the temperature and composition of the top and bottom of the tower are estimated according to the distillation principle,the analysis of the feed composition and the simulation setting of the top recovery,and the composition and flow distribution on the tray is completed by linear interpolation.The initialization method is an improved constant heat transport method.Secondly,the improved group method proposed by Kamath is studied and applied to obtain the temperature,total vapor-liquid flow,and composition of each feed plate and production plate,and the results are summarized and summarized.Finally,the initial values of temperature,total vapor-liquid flow,and composition distribution of the whole tower are obtained.This method is an initialization method based on the group method.The paper verifies the above two initialization methods through two actual distillation separation cases and compares them with the traditional initialization methods.The results show that the time consumption of the distillation simulation initialization method based on the improved constant heat transport model is similar to that of the classical initialization method,but the initial distribution obtained is closer to the final simulation result,which effectively reduces the number of simulation iterations.For the separation process of the non-ideal system,this method can also ensure the convergence performance of the process.Although the initialization method of distillation simulation based on the cluster method can also effectively reduce the number of iterations in the strict calculation process for various separation processes,the process needs to use the cluster method to complete the approximate calculation of the separation process first.The calculation time is relatively long compared with other initialization methods,so the method is only applicable to some highly non-ideal systems and relatively complex distillation models of the separation process.In summary,in the distillation calculation process,when the non-ideality of the separation system is weak and the distillation process is relatively simple,the initialization method based on the improved constant heat transport model can usually be used to complete the initial value estimation of the separation problem.For the highly non-ideal system and the complex separation process of the separation device,the distillation simulation initialization method based on the improved constant heat transport model needs to find out the azeotrope in the separation process during the analysis of the non-ideal system and the operation is difficult to realize in the actual process.Therefore,the distillation simulation initialization method based on the group method is more applicable.