The invention is characterized by a secondary separation zone located in {HEAD ~ the inner free space} between {TAIL ~ the upper and lower walls} and the primary separation devices 
between
The invention is characterized by a secondary separation zone located in { HEAD ~ the inner free space } between { TAIL ~ the upper and lower walls } and the primary separation devices
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH