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Modification of Startup and Hot Shutdown Procedures of RFCC Unit

with Saleh Dayabari, Imam Khomeini Oil Refining Company of Shazand, Iran


The workgroup Safe Startup of FCC and Best Practices follows this presentation, with Hamed Azizi & Saleh Dayabari, Imam Khomeini Oil Refining Company of Shazand, Iran.


Generally startup and shutdown of RFCC is risky and complicated because of large amount of catalyst inventory (1500 ton) and difficulty of tuning parameter affecting catalyst circulation. Many cases have been seen during startup and shutdown of FCC and RFCC units that catalyst circulation is not stable and catalyst carryover from reactor cyclone to main fractionator, making few days delay to restart the unit. Also RFCC shutdown due to withdraw of 1500 ton catalyst inventory is very time consuming and risky.

In this paper,  important parameters affecting RFCC startup and shutdown are investigated. Then licensor procedures reviewed and by modifying startup process and fast stabilization of catalyst circulation, startup time decreased, and risk of catalyst carryover to main fractionator minimized. Also for licensor shutdown procedure, by modifying process and necessary consideration for preventing combustible gas accumulation in regenerator, RFCC hot shutdown procedure without catalyst withdraw proposed. Finally all modified procedures in this paper have been successfully applied in commercial RFCC unit.

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