Study on the System Simulation and Grade Transition Operation for Polystyrene Production Process

• Main Authors: Chun-Kai - Yeh, 葉竣凱
• Other Authors: Hao-yeh Lee
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/90303279947256996347

碩士 === 國立臺灣科技大學 === 化學工程系 === 105 === The main purpose of this study is to simulate the polystyrene production process and develop a strategy for grade transition operation. The reaction kinetics of polystyrene is taken from Hamielec (2004). The process of polystyrene process was based on the flowsheets of Liang (2003) and Wang (2004). After building the steady-state flowsheet of the polystyrene process, the dynamic scheme is also developed for the grade transition operation. Furthermore, the sensitivity analyses of all manipulated variables were also tested to examine the effect on molecular weight of product. This study contains three operation strategies of grade transition problem, namely the base case policy, the overshoot policy and the virtual molecular weight policy, respectively. The base case policy operation method is to adjust all manipulated variables to nominal values of the target, taking 13 hours to complete the grade transition. The overshoot policy operation method is to adjust manipulated variables more effect, and then after a while adjust all manipulated variables to nominal values of another grade. The virtual molecular weight control policy that assumes the product molecular weight can be measured, therefore some virtual molecular weight controller is set to control all manipulated variables. And those trajectories of manipulated variables are approximate as several piece-wise constants for the operation of grade transition. The result shows that the time required for grade transition from grade A to B can be reduced to 5 hours.