Design Of Control System Based On Simulation Of Reactor And Regenerator System Of Gas-solid Dynamic Catalytic Cracking Unit

This dissertation firstly gives an idea of prior process analysis based control loop configuration for control system structure design,and carries out multi-rate operation optimization under the condition of considering the actual operation requirements of the device.The method includes optimization and design,as well as the dynamic optimization strategy of operating variables under the control system when the device is running.Firstly,a basic introduction to the structure design of the control system is given.Based on it,the principle and purpose of the structure design of the control system are briefly introduced.Then,an overall generalization is given from the perspective of variable pairing with methods such as relative gain array(RGA),and a control system structure design method to reduce the design complexity is proposed.Then,the research on the reactor-regenerator system and its model of the controlled object FCCU is introduced,and finally the research status of dynamic optimization is briefly reviewed.The novelty of this dissertation focuses on the following three perspectives:(1)Aiming at the traditional method of control system structure design and the method of RGA,this subject proposes a prior process analysis based control loop configuration method for control system.Most of the control loop configuration methods do not consider the process requirements,and most of the actual production processes are open-loop unstable systems,and these methods can not be well matched.The method of this dissertation firstly designs the main control loop to ensure the safety and stability of the process by analyzing the process of the system and combining the previous design experience and technology.Then by analyzing the remaining operable variables of the system,they are paired with the main controlled variables based on the RGA method.This control system structure design method combines chemical technology with modern theory,which not only ensures the safety of the system operation process and the design effect of the control system structure,but also reduces the complexity of designing the control system structure for a high-dimensional system.(2)For an actual system,it is often necessary to abstract it into a mathematical model when designing the control system structure,and the accuracy of the model will directly affect the final effect of the control system structure design.When the control system is applied to the actual production device,the expected effect is usually not achieved.Therefore,in order to improve the conformity between the design of the control system structure and the effect of practical application,this dissertation takes the catalytic cracking unit reactor-regenerator system as an example,and improves the model of the system.Based on the mathematical model of the reactor-regenerator system established,a refined dynamic model is established,and the model of the reactor and the regenerator is realistically approximated.The dynamic changes of the gas phase are no longer ignored.Through the discrete distributed parameter system model,a time delay is added to the time-varying variables of each riser and coke burning drum in the discrete model.The simulation results show that the refined dynamic model is closer to the actual chemical production process.(3)After the design stage of the control system structure,the switching strategy switches the operating mode of the system to the optimization mode,in which the remaining manipulated variables can be used to optimize the economic performance of the system.In the control system structure design stage,there will be remaining controllable variables.Although the control loop design cannot be carried out,these variables still have other design values.In this subject,these remaining controllable variables are comprehensively analyzed and the actual operation requirements are considered,the operation control is guaranteed by the process constraints,and the operation optimization is carried out according to the objective function,and finally a better production effect is obtained.The above contents have been verified by numerical simulation to be feasible or effective.Finally,the main research content of this topic is summarized,and the future research direction is briefly introduced.