Research On Simulate And Optimize Polysilicon Distillation Process

Polysilicon is fundamental raw material of information industry and new energy industry, Improved Siemens method is the most mature and widely used method in several polysilicon production method. Most polysilicon plant in domestic and foreign using improved Siemens method for producing solar grade and electronic grade polysilicon, but this process requires a lot of energy. The purpose of this thesis is saving energy, saving equipment cost and operation cost using Aspen Plus simulation software for distillation process in polysilicon production.First, deviation of experiment data of vapor liqiuid equilibra was compared with simulated data of vapor liqiuid equilibra of SiHCl3-SiCl4 system and find the thermodynamic model which can describe the feedstock system. The result was that deviation of RK-Soave model have lower error in describing vapor phase equilibrium and deviation of NRTL model have lower error in describing liquid phase equilibrium. So next step, heat capacity data of feedstock system which simulated using different thermodynamic model in Aspen software was compared with caculated heat capacity data of feedstock system using equation. Finally It was find that RK-Soave model was the best one for describing the system.To inspect the reliability of thermodynamic model, the density of feedstock which simulated using different thermodynamic model in Aspen software was compared with caculated density of feedstock system using data from literature. The result showed that thermodynamic model RK-Soave was fit for the system.After thermodynamic model was selected, the single tower was simulated to find the suitable operation parameter. Simulated data was compared with designed data and they are agree quite well. It showed the correct of simulate of single tower.Last, the entire process of trichlorosilane distillation process and tail gas recovery distillation process in polysilicon production was simulated and optimized. The optimal parameters of the the singel tower was determined. The energy, fixed investment cost and was operating cost reduced.