Study On The Control Method Of The Sweet Liquid Enrichment Counter-current Three Effect Evaporator

In the food,pharmaceutical and chemical industry and other industrial production,the evaporator which takes the steam as the heat source is widely used in the concentration process of the raw material.In The Early Period,This kind of evaporator is usually a singl-effect evaporator with high energy consumption and low efficiency.In recent years,the multi-effect evaporator of low energy consumption and high efficiency has gradually replaced the single effect evaporator,the most common for the three-effect evaporator.Most of the early three effect evaporators are manual control,which makes the energy consumption and efficiency in the production process is not ideal,in order to improve the stability of the three-effect evaporator working state,reduce energy consumption and improve efficiency,study the three-effect evaporator Of the automatic control method is of great significance.This paper is commissioned by the Laboratory of Plant Composition Extraction of Guangxi Normal University,The technical transformation plan is designed for the original equipment-manual controlled three-effect evaporator.The equipment is mainly used for the extraction of Mangosteen of the concentration process.According to the characteristics of high viscosity and poor fluidity,it is determined that the working mode of the evaporator is three-way countercurrent self-circulation,and a set of automatic control system is designed according to the process flow.In order to achieve the goal of reducing energy consumption,improving efficiency and convenient operation.The control system takes PLC as the control core,which is installed with MCGS industrial control software of the PC and touch screen for the host computer built.PC is used for process monitoring,touch screen for field control,with automatic control mode and manual control mode.The control of the evaporator is mainly composed of the following parts,the control of the steam pressure,the effect of the separation chamber and the raw material tank level control,the control of the vacuum level of the evaporation chamber,the product of liquid concentration control,the secondary steam flow of the first effect evaporator and so on,in which the control of the secondary steam flow of the first effect evaporator related variables is more and simple PID control has been unable to meet the control requirements,In this article,the feedforward fuzzy PID algorithm is used to design the control of the secondary steam flow.Before writing the PLC control procedures,it is needed on the basis of the identified control strategy for Matlab simulation,to confirm its rationality,and then through the preparation of PLC applications to achieve.After the design of the control system is completed,the simulation test is carried out in the field of industrial control laboratory in our hospital.The simulation results show that the control system can collect the sensor signal correctly,the control action is stable and reliable,and the monitoring interface is working normally.The reforming scheme and the process flow of three effect countercurrent evaporator are introduced in the article,giving the desired device of the selection for technological transformation,Control system schematic,introducing the key program of PLC,the function of real-time monitoring interface of PC,the configuration method and the control function of touch screen interface.And focuses on the principle of the control strategy ofthe secondary steam flow of the first effect evaporator,the simulation of Matlab and the preparation of the control program.