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 {TAIL ~ the air} supplied to {HEAD ~ the following zones} 
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 { TAIL ~ the air } supplied to { HEAD ~ 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 TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD