Design And Optimization Of Valve Positioner

Regulating valve is an indispensable and important equipment in industrial production and pipeline transportation.It is widely used in petroleum exploration and transportation,smelting,chemical pharmaceutical,sewage purification and other fields.The valve positioner is the‘heart’of the regulator,which plays the role of controlling the actuator and the valve body.With the gradual transformation of China’s industrial technology from high-speed development to high quality and stable development,industrial production and material conveying engineering has put forward higher requirements for valve positioner,domestic valve positioner in positioning accuracy,service life and product versatility there is still room for improvement.Therefore,it is of great significance to study the performance of valve positioner and improve the design of current products.In this thesis,TRIZ theory and modular design are combined to research and design valve positioner products,aiming at the defects of valve positioner in positioning accuracy,service life and product versatility.The specific contents are as follows:(1)Based on TRIZ is proposed module reuse concept,and summarizes the primary reuse and secondary reusing process,analysis of the valve positioner features,combined with the internal and external factors affecting the valve positioner internal partitioning module,were divided into potential feedback module,signal processing module,the nozzle baffle module,pneumatic amplifier module and the housing module five modules.Aiming at the defects of positioning accuracy,product life and product versatility of valve positioner,the modules that can be improved,such as nozzle baffle module,pneumatic amplifier module and shell module,were found out.(2)The mechanical equations of the valve spool under open,closed and moving conditions are established.The results show that increasing the back pressure difference can improve the response speed and positioning accuracy of the gas amplifier.According to the law of flow conservation,a mathematical model of the flow in the nozzle baffle was established,and the relationship between the gap of the nozzle baffle and the back pressure in the back pressure chamber(L-P_bcurve)and the relationship between the diameter of the nozzle and the back pressure in the back pressure chamber were obtained.The three-dimensional model of nozzle baffle was established,and the variation trend of lower back pressure value of different nozzle baffle clearance was obtained by using fluid analysis software.(3)According to the reuse idea of modules,three schemes of increasing the diameter of nozzle hole,increasing the length of baffle opening and closing interval,and optimizing L-P_bcurve were put forward to improve the service life and positioning accuracy of valve positioner.Using TRIZ tool to assist analysis,the baffle cavity is added to improve the baffle structure,and the Flow baffle is added to improve the nozzle structure.The above three schemes are realized,and the improved L-P_bcurve of the structure is obtained by using Flow Simulation analysis.The improved nozzle baffle structure increases the selection length of the baffle position interval,and improves the back pressure difference value of the baffle in the open and closed state,thus verifying the feasibility of the improved nozzle baffle structure.(4)The shell type of valve positioner on the market is analyzed,and the factors that affect the universality of the product are found--the structure of the gas path plate is not unified(there are two types of the gas path plate A and B).Taking Tissin TS600 as the research object,the gas-path connection matrix models of A-type and B-type gas-path plates are established,and the general gas-path connection scheme is obtained through matrix transformation and matrix analysis.Triz tool,module reuse idea and fluid analysis software were used to design and optimize the model of gas-path converter board.The model of gas-path transfer plate 1:1was made and installed in the valve positioner,and its feasibility was verified by practical experiments.