Research On The Model-predictive Control System Of Continuous Cross-flow Maize Dryer

Our country is a big country in agriculture and population, soguaranteeing food security is one of our basic state policies. Grain drying is avery important part of food postpartum, and to ensure the work of the graindrying for food security has vital significance. Corn is the main food crops innorthern China, and northern climatic conditions determine the post-harvestcorn must be dried before warehousing storage. The northern region hasalways attached great importance to the development of corn dryingtechnology.However, as maize drying is a typical multi-variables, time dependent,nonlinear and long delay industrial process, it is very difficult to achieveautomatic control. So the research of grain drying process control model,process realization, application and the progress of grain drying technologyhave become a research focus for years.With the rapid development of computer technology, more and moreadvanced control technologies are being used in industrial control applications.Based on the characteristics of the corn drying process, to solve the problemswhich are still exist in automatic control of corn drying process and toimprove the level of automatic control of corn drying process, we will designa model-predictive control system for the continuous cross-flow corn dryerresearched and developed independently by Changchun jida scientificinstruments and equipments Co., LTD., with the help of the model-predictivecontrol technology widely used in the field of industrial control in recentyears.In this proposed model-predictive control solutions, we will the corn moisture sensors, online, intelligent temperature regulator, the corn positionsensors, variable frequency regulator, the RS485-to-RS232module and theS7-200PLC controller and PC etc. hardware; meanwhile we design themodel-predictive control system software for the5HSZ-R-10.0continuouscross-flow corn dryer in the industrial level computing platform with LabVIEW with the help of RS485field bus technology.The following are the main contents.Firstly, according to analyzing the characteristics of the corn dryingprocess, this paper will find out the main factors in corn drying process andthe optimum technological conditions, and we will summarize the parametersof the main factors.Secondly, based on the research achievements in the thin layer dryingexperiment by our country for many years, this paper will simulate thethick-bed corn drying in the industrial level computing platform with LabVIEW using the balance model designed by the United States T.L.Thempsonprofessor, and test validation.Thirdly, according to the computer simulation technology for thick-beddrying process, this paper will analyze the influence of different thickness ofthe corn on grain drying process, and find out the optimum corn layerthickness. We will test and design the model equation for this optimumthickness of corn.Forthly, this paper analyzes structure and production process features ofthe5HSZ-R-10.0continuous cross-flow corn dryer, and then design a newdryer predictive controller based on models containing process model, inverseprocess model and the discharge rate optimizer, and feedback correction.Fifthly, combined with distributed measurement and control technologyused widely in the world, this paper completes the design of the controlsystem software on Lab VIEW, with the help of sensors such as cornmoisture sensor, grain position sensor,all of which are researched anddeveloped independently by Changchun jida scientific instruments and equipments Co., LTD.Finally, we will realize the normal operation of the all control system andthe communication between S7-200PLC and PC by RS485field bustechnology.