Design And Implementation Of PLC Control For Tobacco Vacuum Conditioning

The tobacco industry has always been an important industry in China,and the market demand is very large.With the development of industrial level,the requirement of manufacturing technology is more and more high.Tobacco vacuum conditioning is the critical step of tobacco processing,vacuum conditioning process efficiency directly affects the moisture regain of high and low.Through the investigation of various tobacco factories in Hebei province,it is found that the vacuum conditioning control process is basically controlled by experience at present.A large amount of steam is injected during the conditioning,which leads to high energy consumption and damages the activity of tobacco leaves,and the moisture regain rate is not satisfactory.Therefore,based on the heat balance relationship between steam and water in vacuum conditioning machine,this paper improves the existing tobacco vacuum moisture regain control scheme to control opening of the steam continuous regulating valve and then control the steam injection amount,make sure that steam and water pass through the moisture regain machine in a certain proportion to make the tobacco leaves fully moisture regain loose,in order to improve the moisture regain and reduce energy consumption.In order to realize the fine control of tobacco vacuum conditioning process,this paper carried out the following work:(1)Studied and analyzed the working principle of vacuum conditioning control in tobacco industry,siemens 300 PLC was selected as the controller of the system,this system completed the tobacco vacuum conditioning control system of PLC hardware design,the design scheme meets the actual measurement parameter points,calculation accuracy and valve control requirements of the subject,as well as the communication requirements with intelligent steam instrument,to improve the data accuracy and anti-interference.(2)Analyzed the existing vacuum conditioning control process.The vacuum conditioning control process mainly includes subprocedure of vacuum extraction,moisture regain,pressure retaining and hole breaking.However,due to the imprecise control process,the moisture regain effect is low and energy consumption is high.In this paper,based on the original control flow,based on the heat balance model of steam and water in the vacuum conditioning machine established by the research group,improvedthe existing vacuum conditioning control flow to achieve fine moisture regain control.(3)In order to achieve man-machine interaction,WINCC configuration monitoring interface is used,and STEP7 and WINCC are configured to achieve data communication.This topic design the monitoring interface including the main interface,debugging interface,balance data display interface,variable records.In addition to displaying all measurement data,model calculation data,control,and design the function of configuration,read the EXCEL configuration file to implement the basic configuration of the software,It enables the staff to modify the display variables of the monitoring interface flexibly by modifying the contents of EXCEL sheets,which increases the flexibility of the software.Through the establishment of the experimental machine,the vacuum conditioning experiment of tobacco leaves was completed on site.Compared with the traditional tobacco control,the control scheme in this paper has the characteristics of higher accuracy,higher moisture regain and low energy consumption,which meet the requirements of industrial control and process requirements,and has a good application prospect.