Research On Calculation Method Of The Key Information Index And On-line Monitoring In Grain Drying Process

“World stability after full food”. Grain is the foundation of social stability andnational economy. So grain safety is important in people’s livelihood. Grain drying isthe primary important part after harvesting, which directly affects food safety. Grainare mainly dried through dryers, but when grain in dryer, the key information such astemperature and humidity, state of grain mass, silo capacity, weight and moisture can’tbe observed, which is a blind spot for observing and controlling. This paper hasobserved the calculation and on-line monitoring method of the key information andindex in grain drying process, and build a model for silo capacity and a forecast modelfor moisture based on unit weight by theoretical analysis and experiment, anddeveloped a series on-line monitoring system for grain drying information, whichprovide a new method for data monitoring and automation of grain drying. The maincontents are as follows.（1）Exploring the research status of on-line monitoring for amount and qualityinformation of grain drying process at home and abroad, and analyzing theshortcomings for them. Proposing to use laser ranging technology in the measurementof grain level in drier, and using the silo capacity model of grain dryer to describe theamount, which filled the gaps in research at home and abroad; using the correlationbetween unit weight and moisture to detect moisture on-line.（2）Exploring the calculation method of amount information in grain dryingprocess, and carrying out the research for the model and simulation of dryer silocapacity. Using geometry to analysis the principle of grain pile shape and frustum indryer, proposing to use three fixed point measuring method and rotating scannermethod to measure silo capacity. SOLIDWORKS are applied in simulationexperiments, analyses of the trial data show the important relationship between the effective storage and eccentricity. The greater the eccentricity, the smaller theeffective storage. And draw a conclusion that: The actual design requests square silo’seccentricity within1/5body length, silo’s eccentricity within1/2radius, the silocapacity will have less effect in this range. To calculate the volume of effective silocapacity, proposing an equivalent height of the cone height, then simulated bySOLIDWORKS and disposed by MATLAB, obtained calculation method of grain pilevolume, and established silo capacity models of a square silo and silos. In modeling,the calculation method of the amount information were obtained, such as materiallevel, eccentricity, repose angle et al. The silo capacity model has been validated forthree fixed point measuring on the actual dryers.（3）Exploring the calculation method of quality information in grain dryingprocess, and carrying out the research for the moisture forecasting model based onunit weight. In the drying experimental table, the test of corn unit weight change rulealong with moisture were done on30℃,40℃,50℃,60℃. Data analysisconcluded that the unit weight varies with water is divided into three stages: Swellsarea, smooth area and slow down area. Swells area:26%~23%moisture content, unitweight decreases quickly as moisture content down; smooth area:23%~18%moisture content, unit weight change is not great with the moisture content; slowdown areas: moisture content18%~14%, unit weight decreases slowly as moisturedown. Then established the relation forecast model for moisture temperature, and unitweight by MATALAB, using LABVIEW write model calculation program. Finally,the results of model validation showed that the regression of model is very well (R2=0.9936).（4）Development of grain drying process information online monitoring system.Monitoring system is mainly divided into two parts, hardware and software parts ofthe system. The hardware includes temperature and humidity sensors, load cells, laserranging sensors and PTZ, while designing a laser housing, bracket and weighingmechanism for the sensor. Software system is developed using virtual instrumentLABVIEW. Software design implement serial communication, sensors and PTZcontrol, collection and storage of data, parameter setting, data processing (model program design) as well as control of the system data interface design.（5）Testing the systems in practice production. Testing the developed on-linemonitoring system on the actual dryer5HSZ-R-10.0and5HSZ-R-50.0, experimentsshow that the monitoring system has the monitoring application conditions for criticalinformation indicators during the drying process. Using range method and3σ methodto analyze accuracy of moisture detection, the results show that they are-0.222%~0.78%and-0.142%~0.381%respectively, while there is a gap comparewith the national standards of measurement error±0.5%, but using unit weight tomeasure moisture provide a new direction and idea for on-line monitoring moisture.