The combustion heat generated during incineration of the waste gas mixed with {HEAD ~ the air} establishes {TAIL ~ strong buoyancy} and produces a swirling air stream 
The combustion heat generated during incineration of the waste gas mixed with { HEAD ~ the air } establishes { TAIL ~ strong buoyancy } and produces a swirling air stream
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH