#1 Fluid Catalytic Cracking Unit (#1 FCCU) & #1 Gas Recovery Plant (#1 GRP)

The feedstock to the #1 FCCU, Unit 12, mainly consists of hot vacuum gas oil, from the #1 Crude/Vacuum Unit, and is supplemented with cold imported FCCU feed from storage. The maximum charge to the unit is 14,000 BPSD, however it varies with seasonal conditions and feedstock quality changes. The unit produces Cat. gasolines, Light Cycle Stock, Decant Oil, Propane / Propylene mix, Butane / Butylene mix, and Fuel gas.

The feed, after passing through a fired preheater, enters the unit at the base of the riser where it contacts hot, regenerated catalyst and is vaporized. The heavier gas oil hydrocarbons are cracked to form lighter components as they contact the catalyst in the riser, producing gas, unsaturated LPG, FCCU gasoline, light Cycle oil and residual heavy cycle oils. The cracking reactions will continue for the very short time it takes for the oil vapors / catalyst mix to reach the top of the riser, where they are disengaged in the reactor. The cracked products in the vapor phase leave the reactor overhead and flow to the fractionation section. In the fractionation section / gas plant, the reactor vapors are cooled, compressed, condensed and split into the various product streams.

The cracking reactions are endothermic (absorb energy) and coke is deposited on the circulating catalyst during the process. The spent catalyst flows from the reactor, through the steam stripping section to remove residual hydrocarbons, and into the regenerator. In the Regenerator, air is contacted with the spent catalyst and the coke is burned off to provide regenerated catalyst.

The regenerated catalyst then exits the regenerator via the stand-pipe and circulates back to the base of the riser to restart the process. The heat of combustion raises the catalyst temperature to the 1200 to 1300 F range and thus supplies the heat of reaction, since most of this energy is transferred into cracking the feed in the riser. Cyclones internal to the regenerator vessel retain the catalyst in the circulating system. Hot flue gases exiting the regenerator cyclones are utilized to generate steam in a waste heat recovery system before exiting into the flue stack.

The FCCU main fractionator receives the superheated vapors from the overheads of the Reactor separator. The Reactor contains a riser termination device and cyclones which efficiently separate the catalyst from the hydrocarbon vapors, and minimize catalyst fines losses into the downstream oil separation systems. The main fractionator column quenches, cools, condenses and separates the heavy and light cycle oil products. The overheads vapors enter the FCCU Gas Recovery Plant (#1 GRP), Unit 13, which further recovers the FCCU gasolines and separates the olefinic LPG streams from the fuel gas produced by the cracking process. The Propane / Propylene mix LPG stream is fed to the Propylene splitter section for recovery as a saleable chemical feedstock. The Butane / Butylene mixture is routed into the Alkylation unit. FCCU gasolines are merox treated and routed into the gasoline blending systems.