Soft Sensing Technology And Application In On-Line Measurement Of Polymerization Degree Of Polyvinyl Acetate

Polymer materials have been widely applied to all walks of life and the people's daily lives. With the national economy and people's living standards continuing to improve, people have put forward higher requirements to production efficiency and product quality of polymer materials. However, due to technical or economic reasons, there are many variables in the production process, which are still difficult or impossible to detect by sensors, at the same time, these variables need to be tightly controlled and have close relation with the quality of products. It will affect the quality of products and the stability of the system, which will result to large losses to enterprises.The main task of this paper is on-line detection research of polymerization degree of polyvinyl acetate. After analysis and comparison of methods of different soft sensing building model, based on the nature of polymer products and polymer flow characteristics, soft sensing mathematical models of the polymerization degree is developed and real-time measurement of the polymerization degree is implemented. This soft sensor system is applied to real plants, and good results are obtained. Contents in this paper are as follows:1.The basic concepts of soft sensing technology and its development are introduced, basic conceptions and their development of soft sensing technology covered, and the model-building idea,the four factors and implementation of soft sensor analyzed. The production process of industrial polyvinyl acetate is also briefly given.2.The theories of PCA,PLS,ANN and so on are discussed to pave the way for the later application of soft sensing technology respectively.3.Reaction mechanism of Polyvinyl acetate and its flow characteristics are provided, analyzing the factors which affect polyvinyl acetate polymerization degree, choosing pressure drop across two points in the pipe line, flow rate as secondary variables to build the soft-sensor model of above variables and polymerization degree of polyvinyl acetate. Good results have been obtained when the established model is applied to plants.4.The methods for on-line modeling correction and time match between primary variable and secondary variable are investigated.Finally,conclusions, as well as the future research directions for soft sensing, are given.