Abstract: The ethylene yields of straight-run naphtha, hydrotreated coker naphtha, condensate oil from natural gas and their related desorption oil samples (post to 5A molecular sieve adsorption, rich in normal paraffins) were studied in order to optimize the utilization of cracking feeds and improve the ethylene yield of steam cracking process. The effect of cracking conditions on the cracking performance was also investigated. Under typical industry cracking conditions the ethylene yields of straight-run naphtha, related adsorption raffinate and desorption oil are 29.9%, 23.0% and 41.1%, respectively. It can be seen that the ethylene yield of the desorption oil increases 11.2 percentages as compared with that of naphtha. The total yields of ethylene, propylene and butadiene of desorption oil are 8.4 percentages higher than that of naphtha. For the hydrotreated coker naphtha and the condensate oil, the ethylene yields of their related desorption oils increase 11.1 and 6.5 percentages, respectively. With the increase of cracking temperature, the ethylene and butadiene yields of naphtha and related desorption oil increase notably, yet the propylene yields remain approximately constant.

Key words: naphtha, normal paraffin, steam cracking, ethylene