The Application Of Information Technology For Polyester Division Of Sinopec Shanghai Petrochemical Co., Ltd.

This thesis Addresses novel development of advanced process controlor and inferential sensor system on the PTA plant with Mitsui process technology based on DMCplus controller (Model Predictive Multivariable Control) and Aspen IQ (Inferential Sensor Technology) platform. The advanced control system is designed to achieve smoother operation, increased plant production rate and reduced energy consumption. This results in significant economic benefits for PTA plant. The thesis research procedure can Be summarized as follows:1). Taking the research results on the oxidation mechanism of PX unit conducted by others as the reference to determine the major factors that have the impact on the quality and consumption of the products (PTA), and than using them as the input variables to develop the inferential sensors.2). Collecting a numBer of real process data from the plant and laboratory analysis for developing 7 inferential sensors used for products quality by means of Aspen IQ, and continuously verify/update them until their accuracy is above 95%.3). Improving the basic control system of the plant in order to reduce impact from process disturbances, such as, the disturbances coming from reaction pressures and solvent supplement.4). Conducting plant step test to develop dynamic response models relating each of controlled process parameters and quality variaBles (dependent variables) to the manipulated variaBles (independent variables). 6). Combining the theory with the operating experience to design and develop the controller for achieving multivariable control for the PTA plant.7). Optimizing model predictive multivariaBle controller performance to run the process at the true optimum constraintsThe DMCplus controller was commissioned in august 2002. The benefits associated with the DMCplus control system are realized through smoother operation due to a reduced impact from process disturbances and the constraint handling capability of the controller. This results in improved product quality, 3% increased production rate and reduced consumptions of the catalyst, the solvent and energy. The annual economic benefits from this project is over 13,000,000.00$RMB based on project post-audit.The successful advanced process control system for PTA plant presented in this thesis demonstrates that it bridges a gap at the area of PTA operations using model predictive advanced process control, and it also gives a contribution to improve the competition ability with others in PET industries worldwide.