At the input and output of {HEAD ~ a material} from {TAIL ~ the dryer 15 drum feeders} 18 are installed, playing a role not only as batch feeders, but also as gas sealers, not permitting any external air intake 
At the input and output of { HEAD ~ a material } from { TAIL ~ the dryer 15 drum feeders } 18 are installed , playing a role not only as batch feeders , but also as gas sealers , not permitting any external air intake
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH