Process for debottlenecking fcc wet gas compressor and gas plant

A method for operating a Fluid Catalytic Cracker (FCC) unit in petrochemical mode, the method comprising:

• feeding dry gas and LPG from a FCC fractionator to a wet gas compressor (WGC);
• withdrawing a slip stream from the feed to the WGC and supplying it to an auxiliary compressor and membrane separation system, which auxiliary compressor and membrane separation system is parallel to the WGC;
• compressing the slip stream in the auxiliary compressor to produce a compressed stream;
• feeding the compressed stream to a membrane system comprising a membrane;
• separating the compressed stream into a relatively lighter hydrocarbon component effluent stream and a relatively heavier hydrocarbon component effluent stream via the membrane;
• transporting the relatively lighter hydrocarbon component effluent stream to a C3-C4/naphtha fractionation unit;
• and
• transporting the relatively heavier hydrocarbon component effluent stream to an untreated fuel gas system which in turn feeds a treatment section.