After Changyi Petrochemical reworked the refrigerant cycle of its 1.4-million-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.