Catalyst deposits in FCCU power recovery systems can be controlled

Catalyst deposition throughout a fluid catalytic cracking unit (FCCU) power recovery system can lead to significantly higher maintenance costs, operational problems, and even an FCCU outage. The problem of catalyst deposition is an unusual one that is difficult to understand, predict and eliminate. Field experience with several power recovery systems, including hot-gas expanders, third-stage separators, and top-pressure control valves, reveals some causes of catalyst deposition, preventions for depositions, and procedures to remove the deposits. The overall cycle efficiency of the FCC process can be significantly improved by utilizing various waste energy recovery systems such as CO boilers, waste-heat boilers, and power recovery hot-gas expanders. Millions of dollars per year can be saved by the use of these power recovery systems. But these savings can be significantly reduced by loss of recovery system efficiency caused by deposition of catalyst in the various components that make up the recovery system. Catalyst deposits have been found to occur in the first, second, and third-stage particle separator systems, the process control valves, the power recovery expander, and downstream flue-gas-to-steam boilers. Although only installations with power recovery expanders (Ingersoll-Rand and four other expander manufacturers) are discussed here, similar depositions are known to occur in FCCU'smore » without power recovery expanders.« less