The Design Of Centrifuge Control System Retrofit Scheme Based On Compactlogix PLC

Centrifugal compressor is the key equipment to compress and transport all kinds of gases in chemical production in all kinds of large chemical plants and refineries.However,the performance of the control system directly affects the safety and stability of the compressor.Therefore,it is a key problem to design a new system with advanced functions,stable operation and convenient maintenance on the experience of the original control system.This paper is based on the design project of a centrifugal compressor control system in a petrochemical enterprise.According to the requirement of the actual operation of the equipment,a new design scheme of the new control system is put forward based on the function of the original control system.In the new control scheme,the original LCD display and single board control system was cancelled;Based on the analysis of the process and operation,according to the specific surge problem of centrifuge,the automatic surge detection and anti-surge control strategy are put forward to ensure the safety and long cycle operation of the equipment.The control function of the original system was optimized,and the constant pressure control model was proposed to ensure the stability of the pressure supply process,and to avoid the safety hazards caused by the pressure fluctuations of the pipe network and the equipment itself during the operation process.The position PID algorithm and constant pressure control mode are designed.PLC control system adopts the CompactLogix system of Rockwell Automation Company in the United States,that is,it replaces the original closed system by designing a new control system to transform it,and uses easy-to-read ladder logic to achieve unit control;It has the advantages of generality and easy to popularize.At the same time,a graphical human-computer interface(touch screen)based on the Windows system is designed and used to cancel the original human-computer interface based on character display.Through the MODBUS-RTU protocol,the field data is transmitted to the operator station in the operation room,which enhances the stability of monitoring and data collection of the on-site equipment.Since the system was put into operation,the operating conditions are good,and the changes in the parameters of centrifuges are within the scope of indicators,which reduces the impact of pressure fluctuations on the production process,fully meets the design requirements,and increases the huge economic benefits for enterprises.