ISR research accomplishments
Polymerization Process Engineering
Researcher
K.-Y. Choi (ChE/ISR)
Accomplishment
Our research has been focused on the development of advanced estimation and control techniques for various industrial polymerization process systems. The research projects in the past few years include:
- Optimal Polymer Chain Length Distribution in a Batch Free Radical Polymerization Reactor
- Control of Tensile Strength in a Styrene Polymerization Reactor
- On-Line Estimation and Control in a Continuous Olefin Polymerization Reactor
- Modeling of Industrial Olefin Polymerization Processes
- Modeling and Control of Copolymer Hydrodynamic Volume Distribution
Examples
Method of Finite Molecular Weight Moments for Homo- and Co-Polymerization Processes
In the past, only molecular weight averages have been used to control polymer molecular weight properties. There has been a need to develop new methods to calculate the entire chain length distribution for both homo- and co-polymerization reactions. The method of finite molecular weight moments is based on a kinetic model of a polymerization process. Instead of calculating the concentration of infinite number of polymer molecules of different chain lengths, the weight fractions of polymers in certain finite chain length intervals are calculated using the kinetic equations and the molecular weight moment equations. The proposed computational technique has been validated experimentally for a batch solution polymerization of methyl methacrylate.
The method of finite molecular weight moments has been applied to the design of optimal chain length distribution control for homopolymerization of methyl methacrylate and styrene. The method of finite molecular weight moments has also been extended to a binary copolymerization system where the hydrydyamic volume distribution is calculated and controlled instead of molecular weight distribution which is often dependent on a copolymer composition heterogeneity
Modeling and On-Line Optimal Parameter/State Estimation in Continuous Olefin Polymerization Processes
Dynamic models have been developed for industrial gas phase and slurry phase olefin polymerization reactor processes in collaboration with Exxon Chemical Company, Solvay, and LG Chemical Company. On-line parameter and state estimation techniques have been developed using extended Kalman filter and nonlinear programming techniques for a process with multiple high activity catalyst systems. Computational techniques have been developed for the determination of kinetic parameters for gas phase olefin polymerization using semibatch and continuous reactor data.
Optimal grade transition policies have been developed to reduce grade transition time and off-specification products. Developed process simulators have been delivered to industrial sponsors for their use in designing process control systems.
- Development of new computational techniques (Finite Molecular Weight Moments) for the control of a complete polymer chain length distribution using a detailed kinetic model
- Application of the finite molecular weight moment technique to control polystyrene tensile strength in a batch reactor process
- Development of on-line optimal parameter/state estimation techniques for a continuous gas phase olefin polymerization reactor
- Development of dynamic process models for industrial gas phase olefin polymerization process systems (Exxon Chemical, Solvay, LG Chem)
- Development of a novel technique for the calculation and control of binary copolymer hydrodynamic volume distribution
For more information
On-line monitoring and control of polymerization reactors (T.J. Crowley and K.Y. Choi), Polym. Eng. Sci., 36(1), 65-77 (1996).
On-line parameter estimation in a continuous polymerization process (A. Sirohi and K.Y. Choi), Ind. Eng. Chem. Res., 35, 1332-1343 (1996).
Estimation of kinetic parameters in transition metal catalyzed gas phase olefin copolymerization processes (K.Y. Choi, S. Tang and A. Sirohi), Ind. Eng. Chem. Res., 36, 1095-1102 (1997).
Calculation of molecular weight distribution from molecular weight moments in free radical polymerization (T.J. Crowley and K.Y. Choi), Ind. Eng. Chem. Res., 36, 1419-1423 (1997).
Discrete optimal control of molecular weight distribution in a batch free radical polymerization process (T.J. Crowley and K.Y. Choi), Ind. Eng. Chem. Res., 36, 3676-3684 (1997).
Calculation of molecular weight distribution in a batch thermal polymerization of styrene (W.J. Yoon, J.H. Ryu, C.H. Cheong and K.Y. Choi), Macromol. Theory and Simulations, 7, 327-332 (1998).
Control of molecular weight distribution and tensile strength in a free radical styrene polymerization process (T.J. Crowley and K.Y. Choi), J. Appl. Polym. Sci., 70, 1017-1026 (1998).
Experimental studies on optimal molecular weight distribution control in a batch free radical polymerization process (T.J. Crowley and K.Y. Choi), Chem. Eng. Sci., 53(15), 2769-2790 (1998).
Copolymer hydrodynamic volume distribution in free radical copolymerization processes (T.J. Crowley and K.Y. Choi), Polym. React. Eng., 7(1), 43-70 (1999).
Control of copolymer hydrodynamic volume distribution in a semibatch free radical copolymerization process (T.J. Crowley and K.Y. Choi), Computers and Chem. Eng., 23, 1153-1165 (1999).
