A flow and heat transfer model of oil-gas in a 1.60 Mt/a RFCC disengager was established using computational fluid dynamics (CFD) to solve coking problems of resid fluid catalytic cracking (RFCC) disengager. The distribution of oil-gas velocity, temperature and partial pressure were investigated. The results show that low velocity and high partial pressure of oil-gas is an important reason for disengager coking. Meanwhile, residence time distribution of oil-gas from the primary cyclone standpipe, the primary cyclone dipleg, the secondary cyclone dipleg and the stripper inlet were calculated. The results reveal that coking in disengager is mainly caused by oil-gas from the primary cyclone dipleg due to its big volume and long residence time. Therefore, decrease of oil-gas in the primary cyclone dipleg is the key to eliminate disengager coking.
Journal of Chemical Engineering of Chinese Universities