The Research Of Pressure Control Systems Of Gas Chromatograph For Monitoring VOCs

The use of chromatographic analysis technology for VOCs monitoring has been widely used.There are many factors that affect the accuracy of chromatographic detection,the most important of which is the control of carrier gas pressure.If the pressure of the carrier gas cannot be controlled properly,it will affect the final peak time,which will ultimately affect the measurement accuracy and application effect.Therefore,the research of carrier gas pressure control system has important value and significance.Relying on declared Beijing Science and Technology Commission Project(The Research and Demonstration of Online Monitoring Facilities Applied to Chromatographic Technique's Stationary Exhaust Gas VOCs Total Hydrocarbon and Benzene Series)by Beijing Snow Dilong Technology Co.,Ltd.This paper takes the chromatographic pressure control system of Beijing Snow Dilong Company as the research object,proposes a compound control strategy and method based on fuzzy control and PI control,and designs an electronic pressure control system with China's independent intellectual property rights which gain a better control effect,and has successfully applied to the chromatograph equipment(MODEL6000 online VOCs chromatographic analyzer)produced by Beijing Xuedilong Technology Co.,Ltd.According to the characteristics of pressure control of chromatograph carrier gas,this paper proposes the overall composition of electronic pressure control system and completes the selection of important components and hardware design.Based on the pressure flow characteristics,a mathematical model of pipeline pressure control was established and corresponding simulation analysis was performed.For the situation that traditional PID control is difficult to meet the control requirements,a control method combining fuzzy control and PI control is proposed,and the controller design and field experiments are completed.The experimental results show that the compound control strategy adopted in this paper can meet the precision requirements of the pressure control system,achieve the expected goal of Beijing Snow Dilong Technology Co.,Ltd.,and develop an international advanced level of fixed-source exhaust VOCs total hydrocarbons for the company.Benzene online monitoring equipment provides some theoretical and technical support.