PBM Method Combined With New Relaxation Method For Distillation Simulation

It is well-known that calculation simulation has been widely applied in every field of chemical process. It is used when system can't do experiments. It can predict system's performance and behavior before the system will be built. It is also applied in a manufacturing modern factory when operating condition will be changed. This simulation method is unique and particular.The mathematic model of multistage multi-component distillation is composed of material equation, heat equation, and equilibrium equation, namely MESH equation. The number of these equations is bulky and non-linear. So it is required to solve the equations iteratively. A great deal of method has been presented up to now. It is a hang-up to simulate distillation process of non-ideal system for many scholars. These days a lot of excellent methods have been put forward.This paper presents a combined method for distillation process of non-ideal system, namely NR-PBM arithmetic. The arithmetic combines PBM(Pseudo Binary Mixture) method with NR(New Relaxation) method. It fully makes good use of the characteristics of PBM and NR method.This paper builds a. strict model of NR-PBM arithmetic. Many problems have been discussed including initialization, relaxed factor, converged precision of NR method and converged criterion, damp factor of PBM method. These problems are the key of NR-PBM arithmetic to converge for non-ideal system. This paper selected extractive distillation column and absorb column as example. NR-PBM arithmetic is proved to be a satisfactory and general method.