Studies On Process Modeling And Optimization In Petrochemical Industry

Process modeling and process optimization are two important and high associated issues in Petrochemical industries. With the development trend of globalization of world economy, the pressure to apply the advanced technologies is increasing. Process model is the basis of integrated control technologies in modern Petrochemical industries that contain advanced process control, soft-sensor, process optimization, process scheduling and management. Furthermore, process optimization is and will be a key technology in process industries now and in the near future.This dissertation takes the practical typical plants in Petrochemical industries as the research background. It focuses on several typical theory and engineering issues in petrochemical process modeling and optimization. The whole dissertation is divided into two parts. The first part comprises industrial PTA oxidation process modeling, residual fluid catalytic cracking process modeling, complex distillation modeling and analysis, the application of PTA oxidation process soft-sensor technology. In the second one, the infeasibility degree based genetic algorithm is proposed to handle constrained optimization problem in engineering cases and the neighborhood and archive based genetic algorithm and its variant are proposed to treat the multi-objective optimization problem. With that, the PTA oxidation process is regarded as a benchmark for the application of the proposed multi-objective optimization genetic algorithm. The detailed content is arranged as follows1. A mathematic model to predict the concentration of 4-carboxy-benzaldhyde (4-CBA) for an industrial Purified Terephthalic Acid (PTA) oxidation unit is developed. The model is based on a mechanism model from the results of bench-scale laboratory experiment and chemical reaction principle, which is structured into two series ideal CSTR models. Six plant factors are designed to correct the deviation between the laboratory model and the industrial practice. For the existing of substantial time delays between process variables and quality variable, the weighted moving average method is applied to make each variable be in same time slice. The analysis of process data by projection on latent variables of Partial Least Square (PLS) and analysis of Hotelling's T-squared statistic value of Principal Component Analysis (PCA) are gave to discriminate the operating data into normal operating part and load down and load up operating part. At each operating part, the typical data are selected to regress the plant factors. The proposed model predictive result follows the tracks of the observed value quite well. Compared with the empirical Amoco model, the proposed model is regarded as to bemore suitable to be applied to industrial online soft sensor.2. A novel model for residual fluid catalytic cracking process (RFCC) is proposed. It divides the whole reactor into two part: the riser as ideal pipe flow reactor and the sett -ler as ideal CSTR. The model contains six lumps reaction kinetics with serial and parallel network. The comparison by industrial data proves that the model can predict the produ -ctive rate quite well. The proposed model is suitable to online industrial application.3. Simulation of multistage distillation column is often required for its design and operation. A de-bottleneck study for an acetic acid (HAc) dehydration column is studied in this paper. The column is consists of 4 structural packing sections at the top, a sieve tray section with smaller diameter in the middle and a sieve tray section with larger diam -eter at the bottom. By using steady state simulation, the bottleneck of increasing the effic -iency of separation is identified to be the middle sieve tray section with smaller diameter and smaller tray spacing, and the two renovation schemes without any additional invest -ment on equipment are proposed.4. The development and practical operation of an industrial soft-sensor system for a PTA oxidation unit is introduced. The soft-sensor system is based on a process model,...