REDUCTION OF COKING IN FCCU FEED ZONE

摘要

A method of predicting the tendency of a heavy oil feed to generate coke deposits in the FCC riser under a given set of operating parameters in the unit; thus, by utilizing operating parameters appropriate to the feed, the formation of coke deposits in the riser may be minimized. The margin between the theoretical dew point of the hydrocarbon feed established from unit operating parameters and the theoretical mix zone temperature in the feed injection zone of the unit is developed by applying a regression-derived linear model from multiple rigorous model runs. The mix zone of the unit is then operated at a temperature which reduces the level of riser coking predicted from this ascertainable margin or, at least, maintains it within levels which are predictable and acceptable.

主权项

1. A method of predicting the rate of coke deposit formation in a riser of a fluid catalytic cracking unit having a feed injection/catalyst mix zone in the riser, operating with a heavy hydrocarbon oil feed to the feed injection/catalyst mix zone, which comprises calculating:
(a) A theoretical riser mix zone temperature and (b) a theoretical hydrocarbon feed dew point from factors comprising:
Feed volumetric flow rate and temperatureFeed injection steam mass flow rate and temperatureCatalyst circulation mass flow rate from the regenerator and its temperatureFeed weighted average boiling point andRiser pressure in the mix zoneapplying a linear regression analysis to predict (a) and (b) to determine the margin between the theoretical hydrocarbon feed dew points and the amount of unvaporized feed.