An average residence time of {TAIL ~ between 5 and 500 milliseconds} of {HEAD ~ the hydrocarbons} during thermal cracking has proven to be effective 
An average residence time of { TAIL ~ between 5 and 500 milliseconds } of { HEAD ~ the hydrocarbons } during thermal cracking has proven to be effective
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH