Study On The Control System Of The Gas-liquid Two-phase CO₂ Flow Rig

Global warming is closely related to the increase of the concentration of greenhouse gases in the atmosphere.CO₂ capture,use and storage?CCUS?as an effective way of reducing CO₂ emissions,is increasingly received attention at home and abroad.In order to study the flow measurement of the pipelines transportation in CCUS system,a gas-liquid two-phase CO₂ flow rig was developed by Tianjin University flow lab and North China Electric Power University.The temperature is designed range from 20?³0?,and the pressure is 5.7⁷.2 MPa,to simulate CCUS transport operating conditions.Normal temperature and high temperature make the state of CO₂changeable and difficult to control.At the same time,high pressure make the rig have certain risk.Therefore,high requirements are made upon the control system of the rig.Among them,the flow stability control of the gas-liquid two-phase CO₂ flow rig is important and difficult.Based on gas-liquid two-phase CO₂ flow standard rig,the major researches were completed as follows in the paper.Firstly,aiming at the control method of gas-liquid two-phase CO₂ flow standard rig,the design principle of the rig was studied,the requirement of the control system was analyzed,and the control structure was designed.The control system of the gas-liquid two-phase CO₂ flow standard rig was developed from hardware and software.Secondly,in order to improve the flow stability of gas-liquid two-phase CO₂flow rig,the structure of flow stability control system was put forward,and the control strategy of the gas-liquid two-phase CO₂ flow rig was designed to improve the flow stability through by comprehensively considered the inter-coupling between the temperature,the pressure and flow rate based on analyzing the influence factors of the flow stability.The flow stability control software of gas-liquid two-phase CO₂ flow rig was made analyzing the influence factors of the flow stability and considering the interaction between the temperature,the pressure and flow rate.Based onaccording to the control strategy,the software was programmed.Experimental tests of CO₂ flow stability were carried out under different temperature and pressure conditions.It was shown by the test data that both the flow stabilities of single-phase liquid and gas CO₂are better than 0.5%,the temperature stability at gas-liquid two-phase test section is better than 0.5?/h,and the pressure stability is better than 0.05 MPa/h.Thirdly,aiming at gas-liquid two-phase CO₂ flow standard rig,a local monitoring system and a remote monitoring system were designed.The local monitoring system was designed by MCGS and VB,which can achieve the function of on-site supervision and control,The remote monitoring system was designed by Qt and data base,which can achieve the function of remote data access and device control.Tests of the remotr monitoring system were carried out on water standard facility in Tianjin University flow lab.It was shown that the remote monitoring system has good performance.