Research On Control Strategy Of Heavy Oil Catalytic Cracking Fractionator

In China's current industrial industry,petroleum is still an important source of industrial energy.Most of the crude oil in China is heavy crude oil,which needs to be treated lightly before it can be used in industrial production.As the main equipment to lighten heavy oil,heavy oil FCC fractionator has become the core equipment and industry pillar of petrochemical enterprises in crude oil deep processing.Ensuring its high quality,high efficiency,safe and stable operation,the research on its control strategy is one of the hot spots in the industry.Heavy oil catalytic cracking of fractionating column is a typical multiple input multiple output object with complex internal mechanism,multiple channels,multiple process variables,the control circuit has different large delay and the coupling between variables severe complex features.The study of its control strategy is of great significance.In this thesis,a time series model predictive control algorithm based on Laguerre orthogonal basis optimization is proposed for heavy oil FCC fractionation column system.Combined with the advantages of the traditional control strategy,the improved algorithm is applied to the heavy oil FCC fractionation column system.In addition,based on the knowledge of hybrid system,a MLD Model of heavy oil FCC fractionation column system is established,and the MPC algorithm based on the model is simulated.The main contents of this thesis include:(1)Using Laguerre orthogonal basis expanding the coefficient of ARX model,generalize to multi-variable system,and derives the model predictive control algorithm based on the multivariable ARX-Laguerre model,and combined with PID control to improve performance,put forward MALMPC-PID algorithm,then apply it to heavy oil FCC fractionation column.The simulation results show that the algorithm for heavy oil FCC fractionation column system has good control effect.(2)On the basis of(1),replace PID with the fractional order PID,and the MALMPCFOPID control algorithm is derived.There are more parameters of FOPID,and in the process of simulation,the parameter selection mainly depends on the prior knowledge and human tuning,so the workload is large but the value is not accurate enough.In this thesis,the differential evolution algorithm is used to self-tuning the fractional-order PID parameters.The simulation results show that the algorithm has excellent control effect of heavy oil FCC fractionation column.(3)According to the safety problems existing in the actual production of heavy oil FCC fractionation column,the safety valve signal of storage tank level in the actual production process is simplified as the control of system input into the system.Analyzing the hybrid characteristics of the model under the framework of DHA,and establishing the MLD model by using HYSDEL.Finally,the MPC based on MLD model is used to control the heavy oil FCC fractionation column system,and the simulation results show that the algorithm is effective.