Research On Drying Mechanism And Control Method Of PVA Hydrosol

Polyvinyl alcohol (PVA) film is known as a popular research direction because of its special excellent characteristics in many aspects, e.g. water solubility and degradability. Thin-layer drying characteristics and different drying technology experiment of PVA water-soluble were researched in this paper, and then improved far infrared radiation and hot airflow control program.In the process of making PVA water-soluble film, drying parameter will influence drying rate and energy cosumption in drying system. The suitable method and technological parameter to dry the PVA water-soluble film by casting on the steel band is studied using the homemade far infrared united with hot airflow drying tester. The thin-layer drying characteristics of PVA water-soluble were determined at different air temperatures and air velocities; multi-linear regression was used to determine the parameter values in thin-layer models. A comparison between experimental and predicated data by PAGE equation for the PVA water-soluble was done. It indicated that the equation of PAGE can reflect PVA water-soluble thin-layer's discipline very well.Based on the technological parameters (far infrared distant, the initial water content and film thickness) of PVA hydrosol drying are coupled, so the quadratic rotation-orthogonal combination design was adopted to design the experiment. With DPS (data processing system) to deal with the datum which were derived in the experiment, and then the optimized and combined technological parameters achieved through the analysis testing to the integrative index.This paper improved far infrared radiation and hot airflow control system as the old PVA water-soluble dryer is non-automatic, big energy expending etc. In far infrared radiation facet, put forward a complex temperature control scheme that adopt division-control based on the vary demands at each heating moment. In hot airflow aspect, the automatic control system is based on the technology of PID frequency conversion speeding adjustment, PID temperature control and Modbus fieldbus communication protocol. Therefore, the speed of conveyer, the temperature and humidity in the dryer are adjusted. Accordingly the adaptive curve of the drying is formed. The new system will raise the rate of the pass product and reduces the energy consumption.