Control of product quality in polymerization processes

The increasingly aggressive global competition for the production of higher quality polymer products at lower costs, along with a general trend away from new capital investments in the U.S., has placed considerable pressure on the process engineers in the U.S. to operate the existing polymer plants more efficiently and to use the same plant for the production of many different polymer products. The more efficient operation has been realized by better process control and monitoring while the available polymer product-quality sensors have been inadequate. Although many product quality indices cannot be measured readily, they can be estimated/inferred in real time from the readily available measurements, allowing for inferential control of the polymer product quality. This paper presents a survey of the issues in controlling and monitoring plant-product quality indices such as molecular weight, copolymer composition, and particle size distributions in polymerization reactors. Examples will be given to illustrate some of the methods surveyed.