Research On Modeling And Control Of Heat Pump Assisted Distillation Process

Distillation operations are of great significance for process industry. However, they also consume quite a lot of energy. Traditional distillation operations are not efficient enough and considerable energy is wasted in vain. Heat pump assisted distillation is one of the effective approaches introduced to solve this problem. After compressed, the column top vapor can be used to vaporize material in the bottom of column. In this distillation column, energy is pumped from the top of the column (low temperature) to the bottom of the column (high temperature) so as to maintain the function of column. However, column equipped with heat pump will be more coupling and unstable comparing with traditional column. Thus, it goes more difficult to select proper control structure and operating points in a heuristic matter to make the operation optimal. In this thesis, control and optimization of heat pump assisted distillation is studied based on a mechanism model. The main works are as follows:1. CHAPTER 1 discusses some practical methods used to save energy. The principle and schemas of heat pump assisted column will be discussed at length. Also, control structure design of complex multi-variable processes will be introduced here. Previous work on design, control and optimization of heat pump assisted distillation process will be synthesized there.2. CHAPERT 2 discusses the modeling of vapor recompression heat pump assisted distillation column in a mechanism way. The first principle model can describe the dynamic behavior of the column. Also, the numeric calculation of the model will be expatiated there.3. Comparing with the traditional distillation column, system dynamic character of the heat pump assisted column will be discussed fully in CHAPTER 3. Steady state excursion of heat pump assisted distillation process caused by operating point shift will also be analyzed there.4. CHAPTER 4 will select self-optimizing control structure and operating point for the heat pump assisted column based on its first-principle model. Also, dynamic performance will be compared between different control structures in order toexpand the conception of self-optimizing control.Finally, the work of this thesis is summarized. Also, some comments and prospects are made on the modeling, numeric calculation and control system design problems about complex multi-variable processes.