At the lake charles, Louisiana, refinery of the Cities Service Refining Corporation there are three large fluid catalytic cracking plants operating to crack high boiling gas oils into low boiling hydrocarbons in the gasoline range. The gas and gasoline from the cracking units are sent to a fractionation unit where they are separated into the desired streams.
To explain the corrosion problems, it will be necessary to describe these units, limiting the description to those parts of the plants which have caused, or were expected to cause, trouble from corrosion. The cracking units will be covered first, omitting, however, any discussion of straight erosive attack.
As shown in Figure 1, hot catalyst from the regenerator mixed with hot gas oil passes up through two 25-inch I.D. feed lines into the reactor. (This catalyst is a solid so finely divided it flows like a fluid.) This mixture is distributed uniformly...
