Research On Optimization Approach Of Refining Process System And Its Application

In order to overcome the inherent disadvantages of line programming and single-unit nonlinear optimization, the modeling approach and optimization algorithm of refining system and their applications in refinery-wide optimization are studied in this dissertation. The main contents are as follows:1. Using the decomposition-coordination theory of large-scale system for reference, a novel decomposition strategy for process system optimization, namely two level decomposition-coordination approach, is presented based on the comparison and analysis of current modeling approaches. This approach decomposes the overall model into two levels, namely a system level and a process level. The system level determines common issues among processes; the process level optimizes individual processes. In this way, this approach provides the flexibility of replacing existing process models without affecting the optimization infrastructure.2. For refining process optimization has the characteristics of few degrees of freedom, an efficient optimization algorithm based on reduced sequential quadratic programming and automatic differentiation is presented in this paper. The experiment results show that the new algorithm calculate efficiently and is especially suitable for large-scale process optimization.3. Using Xuan's model of crude distillation unit for reference, a first-principle, nonlinear, crude unit model was developed. The model, which is a steady-state model based on material balance and energy balance, include detailed model of Atmospheric Tower and Vacuum Tower and simplified model of some auxiliary process, such as Rerun unit, Residue Oil Solvent Extraction Unit, Debutanizer, and Naphtha Splitter. The comparison of the developed model and rigorous model shows that this model calculates the yields and properties of the products accurately based on the feed information.4. According to the specific fuel-oriented refinery, Ellis' model of fluidized catalytic cracking (FCC) unit and Taskar's model of catalytic reformer (CR) unit were used in this work after modification. The feed characterization of FCC and CR unit are studied. Each single-unit model was benchmarked against the industrial data obtained from the refinery. Common approaches and principles of lumping kinetic model research are also discussed.5. Simplified models were developed for gas plant, alkylation unit and diesel hydrotreater. Gasoline blending model was developed based on the studies on octane blending model, vapor pressure blending model and percent distilled model, which calculates the gasoline specifications of three grades of gasoline from the information of gasoline blending stocks.6. The objective, decision variables and constraints of refinery-wide optimization are given...