Fluid Proportional Dosing Control And Monitoring System Design Of Diaphragm Metering Pump Groups

Diaphragm metering pump is widely used in chemical,petroleum,pharmaceutical and other fluid dosing industries due to its measurable,controllable and adjustable characteristics.Pump group are often used to expand the delivery capacity of industrial production.The proportional relationship between the flow rates of various fluid media added affects the quality of the end product.Because of the pump group system are a multivariable,nonlinear,strongly coupled system,the traditional electrical connection structure of pump group and control algorithm has low control precision when the pump group are affected by internal and external disturbances.It is easier to make imbalance between the amount of fluid being dosed.The complexity of pump group operation and the medium delivered by the pump are often corrosive liquids,which is not conducive to personnel on-site operation.Therefore,this thesis proposes a proportional synchronization control of pump group based on adjacent deviation coupling structure,by using cascade control structure that the secondary loop uses the active disturbance rejection control to deal with the high-frequency disturbance of the nonlinear system and the main loop uses the generalized predictive control to deal with the low-frequency disturbance and the system delay problem to realize the high-precision flow proportional addition control finally.Based on the communication method of Ethernet and fieldbus,a small-scale dedicated remote monitoring software for metering pumps is developed in Java language to realize remote real-time monitoring and control of the pump group.The main research work and innovations of this thesis are as follows:(1)Based on the analysis of the principle of variable frequency regulation flow and the adjacent deviation coupling synchronization structure,this thesis derives a proportional synchronization structure to achieve a proportional injection of pump group flow.By analyzing the deficiencies of the traditional control algorithm for the characteristics of the pump control object,active disturbance rejection control is adopted to optimize control effect by using the method of observation and compensation.At last,the tuning method is given for its control parameters which are difficult to adjust.(2)Because of the problem of time delay,nonlinear and hard to build accurate model for the pump group fluid dosing system model,the thesis proposed to adopt cascade control mode.The main loop uses generalized predictive control to improve system robustness.In order to improve the efficiency of algorithm execution,the algorithm is written in the Java language and run on the PC side by networked method,and finally verifying the effectiveness of the algorithm on actual engineering control.(3)According to the industrial production characteristics of the metering pump,it is proposed to design a set of special metering pump group fluid dosing remote monitoring software.The software uses Java as the development language and adopts a modular development approach.The functions include network communication using the Mina framework,pump group parameter setting,start and stop control and frequency modulation,real-time curve show,integrating the generalized predictive control algorithm and so on.