Integration of Statistical and Engineering Process Control in a Continuous Polymerization Process

Abstract

The purpose of this article is to present a case study of integrating statistical process control (SPC) and engineering process control (EPC) in an industrial polymerization process. We develop and compare the effectiveness of several regulation strategies to reduce polymer viscosity deviations from target. Controllers are derived using the constrained minimum variance criterion. Robustness properties and stability conditions of the controllers are discussed. The performance and the adequacy of the regulation schemes in a simulation of realistic assignable causes affecting the process are studied. In this context the benefits of implementing an integrated EPC/SPC system are compared with those of using an EPC system alone.

KEY WORDS:

• Constrained controller
• Control charts
• Minimum variance controller
• Process monitoring
• Process regulation