Based On LabVIEW And BP Neural Network 50,000 Tons/year NaOH Evaporation Section Monitoring System Design

Sodium hydroxide,strong base,is a white crystalline at room temperature.It has an extremely wide application in industrial manufacturing.Liquid level because of its characteristics of time-varying,nonlinearity,large-time delay and uncertainty is regarded as the common process control object in the process of sodium hydroxide production.As the process control objectives become more and more complex and the higher control performances are expected,it is very hard to obtain ideal effects using traditional instruments.Chemical virtual instrument system is based on software,which can quickly and accurately complete automatic data acquisition,real-time display,data-depth analysis in the process of chemical production,show a number of test and control functions in the same panel,and improves the accuracy of test results and the degree of automation control.Control system designed by LabVIEW graphical programming has a short development time and the setting of adding and changing is flexible and intuitive,which greatly improve the performance of chemical industry automation control,reduce the production cost and make the data collection is more accurate and quick.Therefore,LabVIEW occupies more and more important status in the field of chemical industry.This article first introduces the application of the LabVIEW virtual instrument in chemical industry.Then,we discuss the production technology of 50%sodium hydroxide.We select the three effect countercurrent evaporation process,calculate the corresponding parameters by the principle of material balance and energy balance and set up the liquid level model for every aporators.Finally,we finish the simulation monitoring of the liquid level of evaporative section of the 50,000tons/year of sodium hydroxide based on the LabVIEW software.The design of login screen can effectively guarantee the safety of data and technology;The design of process presentation interface can achieve the simulation of actual production and dynamic demonstrate the operation of the production equipment;The data processing module is designed to store the data of the production and to realize the data calling by condition;Alarm module design includes sound and light alarm.When the liquid level value more than the highest warning level,the sound and light alarm prompt the staff,which can prevent the happening of the accident;The purpose of automatically or manually switch module is manually adjusting the opening of butterfly valve to control the flow of feed liquid by operator when the automatically control system is error or control effect is not ideal;Liquid level automatic control module system mainly uses the BPNN-based PID controller to control the valve of each effect evaporator.Valve increases from 0.If the liquid level exceeds the highest level value,the alarm lamp lights and the sound alarm sounds.And the same time,the opening of valve decreases to keep liquid level in the ideal level.