Development of PLC Controlled Pelletized Seeds Hollow Square Drying Device

Aiming at problems of large area and high energy consumption of rotary hot air seed drying device，a double barrel PLC controlled drying device was designed and developed.The device included inner and outer cylinders，tugs，servo motors，reducers，couplings，gears，ring gears and brackets.Drying cylinder was designed as a double cylinder inside and outside，and the seeds moved back and forth in inner and outer cylinders to shorten length of whole machine and reduce heat loss.According to dynamic estimation，parameters of pinion and large gear were determined，and SL90 type cross slide coupling with nominal torque of 250 N·m was configured.Control system was developed based on Siemens S7-200 PLC.The motor of type of Anchuan SGM7J-08A was selected to control rotation of mechanical components，with rated output power of 0.75 kW.Communication between PLC and servo motor corresponded to digital to analog conversion of 0~10V and 0~32000，and servo motor was driven by upper command.Experimental tests showed that maximum speed was 50 r/min，drying temperature was 50 ~ 60 ℃，and the power was 0.55 kW.Drying efficiency of pelleted tomato seeds was 10 kg/h，after 60 min drying，moisture content was reduced by 10%.The developed pelleting seed drying device could realize intelligent control of rotation speed，and length of whole machine was 40% less than that of single cylinder type，which could reduce heat loss and improve heat utilization rate.