After Changyi Petrochemical reworked the refrigerant cycle of its 1.4 mln ton catalytic cracking unit (FCCU) it substantially increased handling capacity, decreased unit energy consumption, and balanced product distribution. This means a savings of 12,000 tons of standard coal per year, and an increase of 150-yuan per ton in profits, and 175-million yuan per year in total profit, compared with last year. Changyi Petrochemical developed the FCCU and modification and was able to use the high-activity catalyst to full effect with low temperature contacts and high catalyst-to-oil ratio, for an increase in the overall yield and gasoline octane rating.
The newly modified FCCU can adjust the reaction temperature and catalyst-to-oil ratio independently, which means activity catalyst, adequate space and reaction time for a secondary reaction of gasoline, and lower interference of gasoline upgrading and heavy oil cracking with other. Also, the sharp drop in dry gas, the main product of thermal cracking, means a more favorable condition for transfer reactions from thiophenic sulfides to H2S.