Fluid Cat-Cracking FCC

Fluid catalytic cracking, fluid cat-cracking or FCC, is a common oil refinery process. The duty of an FCC unit is to take a heavy low value gas oil or fuel oil and convert this to higher valued liquid products, particularly gasoline blend-stock. The process also produces diesel fuel blend-stock and a gas by-product stream. The gaseous by-products are rich in olefins and in particular propylene and isobutene. Ethylene is a minor component. 

FCC unit operations are the central feature of many refineries. Often it is physically the largest unit present in a refinery. It has been under development over many decades and has developed to use residual fuel oil rather than gas oil as the feedstock. In another development, catalysts have been developed to lift the level of propylene produced so that an FCC unit can produce considerable quantities of propylene as well as gasoline blend-stock. FCC units produce a major portion of the chemical propylene in many countries such as the USA and Australia. 

In the separator unit, steam separates the catalyst from the hydrocarbon products. The internals of the stripping unit contain cyclones which remove residual catalyst from the hydrocarbon fluids. The fluids flow to a distillation column which separates the products into various fractions. 

The column bottoms (referred to as slurry decant oil) pass to heavy oil processing units or are blended into heavy fuel oil. The heavy gas oil fraction (sometimes called heavy cycle oil) is recycled or used as blend-stock for heavy diesel or industrial fuel oil. The light gas oil (sometimes called light cycle oil) is used for diesel blend-stock. The most important product is the gasoline component which goes to gasoline blending. The 

Propylene exiting the gas plant is suitable for many refinery and chemical operations. For polypropylene manufacturing further purification is required to protect downstream units from traces of acetylenes and allene which may be produced. 

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In the second application, we discuss the use of surface charging concepts and zeta potential measurements to optimize the attrition resistance of fluid cat cracking (FCC) catalyst composite particles. The FCC particles consist of micron size zeolite particles held together by submicron sol particles to form 50-70p composites. In this study, we start with a suite of USY zeohtes of variable bulk Si-Al ratios and first determine their relative surface compositions using isoelectric points (lEP). We estabhshed an excellent... 

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