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From the overhead receiver, the water is then pumped to the sour water stripper. Reverse cascading requires one less pump, but a portion of cyanide captured in the second stage is released in the interstage, forming a cyanide recycle. Consequently, forward cascading is more effective in minimizing cyanide attack. TREATING FACILITIES The gas plant products, namely fuel gas, C3'S, C4's, and gasoline, contain sulfur compounds that require treatment. Impurities in the gas plant products are acidic in nature.

Process Description 15 Air provides oxygen for the combustion of coke and is supplied by one or more air blowers. The air blower provides sufficient air velocity and pressure to maintain the catalyst bed in a fluid state. The air enters the regenerator through an air distributor (Figure 1-11) located near the bottom of the vessel. The design of an air distributor is important in achieving efficient and reliable catalyst regeneration. 0 psi (7 to 15 Kpa) pressure drop to ensure positive air flow through all nozzles.

Heavy components are absorbed in the oil. Two sources of absorption oil are normally utilized in this tower. The first is the hydrocarbon liquid from the main fractionator overhead receiver. This stream, often called "wild," or unstabilized, naphtha, enters the absorber a few trays below the top tray. The second absorbent is cooled debutanized gasoline, which generally enters on the top tray. It has a lower vapor pressure and can be considered a trim absorbent. The expression "lean oil" generally refers to the debutanized gasoline plus the unstabilized naphtha from the overhead receiver.