FCC plant

Within the FCC plant shown in Figure 6-43, eatalyst is eontinuously eireulated between die reaetor and die regenerator. In die regenerator, earbon dial was deposed on die eatalyst is burned off, with eombustion air being supplied on a eontinuous basis. Reaetivated eatalyst from die regenerator is mixed widi FCC feedstoek and dien remrned to die reaetor. 

The refinery restarted their FCC plant approximately 30 hours earlier than originally seheduled. 

Today more than 600 commercial FFB reactors are in operation worldwide, over 350 of which are riser FCC plants. These riser FCC units produce over one-half of the world commercial gasoline. In China, over 90% of the FCC plants are riser reactors. The total number is more than 83 units, and the processing capacity ranks second, following that of the United States. 

Figure 16.1. A mechanism proposed for the action of Ce02 Mg0 based catalyst in the treatment of SO2 in FCC plants [9], Left action performed by MgO right action performed by CcOj.

The control of the FCC unit is an exhaustively studied topic in the literature as well as in the industrial practice. Since the FCC units produce large amount of valuable products their control has a paramount importance. There have been several works to improve its control e.g. Pohlenz, (1970), Lee et al. (1989), Kurihara, (1967), Worldwide Refining Survey (2001) and Advanced Control and Information Systems (2(X)1). For the improvement of the control of the existing FCC plant the Rough Set Theory is tested and used. 

FCC plants are used to convert vacuum gas oil (often mixed with residues from atmospheric distillation, vacuum distillation and visbreaking) into lighter hydrocarbon fractions. The products are a gas fraction (primarily C3/C4), a liquid fraction (primarily gasoline) and solid coke. The coke is deposited on the catalyst and burnt off during catalyst regeneration (see Fig. 2.46). 

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