Fluid Catalytic Cracking Unit (FCCU) is a major conversion unit in the modern refineries. It converts high boiling range hydrocarbon streams, to more valuable streams such as Gasoline and Liquefied Petroleum Gas (LPG). FCCU's make a major contribution to refineries economical benefits. As such, all refiners try to optimize the operation of this unit. One way to optimize the operation of FCCU is to select the best feed alternatives to the unit, to achieve maximum conversion to valuable streams and to better operate the unit at ultimate safe condition. This paper describes the Jeddah Refinery efforts in optimizing the FCCU which switched the feed from the normal "clean & costly" streams to more heavy "dirty" streams. The switch to the heavy "dirty" feed can contribute positively to the refinery economics an amount of 3.5 million dollars annually.


The Fluid Catalytic Cracking unit ‘FCCU’ one of the most important units in Oil Refining Complexes as it produces valuable products from very low quality and value feedstocks. The feedstock quality is one of the most important factors affecting FCCU performance and economics. Therefore, it is essential that the FCCU feedstocks meet the criteria specified by product selectivity, product quality requirements, catalyst, FCCU constraints and above all the overall Refinery economics. Several sophisticated techniques are used to evaluate FCCU feeds such as pilot plants in research laboratories and simulation programs as well. Some of these techniques do not take into consideration the Refinery overall economical benefits, i.e. considering only the FCCU as one box and not optimizing the whole Refinery. This paper describes a technique which was used by Saudi Aramco - Jeddah Refinery to come up with the Optimum overall Refinery feed selection for the FCCU.

Background Saudi Aramco - Jeddah Refinery is a refinery located in the city of Jeddah on the West coast of Saudi Arabia. The Refinery sustainable topping capacity is 100,000 barrels per day. The refinery also, has an FCCU with a 20,000 barrels a day capacity, a small reformer, treating units and own utilities production.

The FCCU converts low value heavy hydrocarbons to valuable lighter components, such as Liquefied Petroleum Gas (LPG), Gasoline and Diesel components. This unit utilizes the "fluidized" catalyst and high temperature (~ 510 C) in this conversion process. The FCCU feed at the Jeddah Refinery sources are as shown in Table 3 with respected percentage from each stream as shown in the right hand side column of the table.

In mid 90's, the idea of optimizing the FCCU feed was raised in the Refinery, as the refinery has several options as FCCU feed streams (Table 3). These streams include the own refinery vacuum Gas oils and the adjacent Lube Oil refiner

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