It is advantageous to maintain the temperature of the air supplied to the first zone, into which the tetrahydrate is also usually first introduced, below that of {HEAD ~ the air} supplied to {TAIL ~ the following zones} 
supplied to
It is advantageous to maintain the temperature of the air supplied to the first zone , into which the tetrahydrate is also usually first introduced , below that of { HEAD ~ the air } supplied to { TAIL ~ the following zones }
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 OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL