Energy Recovery System for Fluid Catalytic Cracking Units

This paper describes the power and heat recovery processes and equipment for modern fluid catalytic cracking (FCC) units made possible by improvements in catalyst fines removal technology and the availability of erosion resistant high temperature hot gas expanders. Flue gas from the FCC regenerator passes through a special cyclone separator to remove most of the entrained catalyst fines. It then enters the expander train to generate power for the compressor which supplies air to the regenerator, and produces electricity for export. The sensible heat in the exhaust from the expander is further recovered in a waste heat boiler. A typical expander train consists of a hot gas expander, an air compressor, an auxiliary steam turbine for start-up, and a motor/generator for generating electricity. Different expander train arrangements are discussed. A comparison of economics of the power recovery system and heat recovery system is presented