It is a characteristic feature of the invention that {HEAD ~ the air} fed to at least one air level is preheated by using {TAIL ~ vapor} generated in the concentration of the black liquor as heat source 
It is a characteristic feature of the invention that { HEAD ~ the air } fed to at least one air level is preheated by using { TAIL ~ vapor } generated in the concentration of the black liquor as heat source
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH