Operating fluid catalytic cracking

An increase in conversion operations (fluid catalytic cracking and visbreaking) which means more phenol and sulfide discharges. This is compounded by the fact that recycling spent caustic downstream from the desalter may be excluded by visbreaker feed Na requirements, Tliis is why all prior stripping operations and flow segregations on the condensates from these units must he well planned and enhanced. 

The MTO process employs a turbulent fluid-bed reactor system and typical conversions exceed 99.9%. The coked catalyst is continuously withdrawn from the reactor and burned in a regenerator. Coke yield and catalyst circulation are an order of magnitude lower than in fluid catalytic cracking (FCC). The MTO process was first scaled up in a 0.64 m /d (4 bbl/d) pilot plant and a successfiil 15.9 m /d (100 bbl/d) demonstration plant was operated in Germany with U.S. and German government support. 

Fluid catalytic cracking and hydrocracking are two additional processes that are often encountered. There are many other processes used in refineries not mentioned here. The list above is intended only to emphasize the wide diversity of processing which is common to petroleum refinuig and to introduce in a very general way some of the more important of these processes. Also it must be emphasized that only fundamental principles of refinery operations have been discussed and modern manufacturing techniques vary widely from company to company. 

Product separation for main fractionators is also often called black oil separation. Main fractionators are typically used for such operations as preflash separation, atmospheric crude, gas oil crude, vacuum preflash crude, vacuum crude, visbreaking, coking, and fluid catalytic cracking. In all these services the object is to recover clean, boiling range components from a black multicomponent mixture. But main fractionators are also used in hydrocracker downstream processing. This operation has a clean feed. Nevertheless, whenever you hear the term black oil, understand that what is really meant is main fractionator processing. 

Various companies worked on the development of Fluid catalytic cracking units. During World War II, the government requested some of the leaders in this field to pool their knowledge so as to speed the production of aviation gasoline. The fact that so many Fluid units were constructed and put into operation in such a short time shows that this joint effort was successful. However, because of this effort, many of the basic Fluid patents were held for many years in combination with other companies, some of which also developed their own Fluid designs. 

Since 1945, the fluid catalytic cracking process has rapidly overtaken fuel production and has become the central technology in the U.S. petrochemicals industi y. With fluid cracking, the scale of petrochemical operations grew eiinriiiotisly. For the first time, refiners could process virtually any volume of oil rapidly and efficiently. 

Fluid catalytic cracking (FCC) continues to play a key role in an integrated refinery as the primary conversion process. For many refiners, the cat cracker is the key to profitability in that the successful operation of the unit determines whether or not the refiner can remain competitive in today s market. 

MSCC [Millisecond catalytic cracking] A fluid catalytic cracking process which uses an ultra-short contact time reaction system. It is claimed that less capital investment and higher liquid yields can be achieved using this process, compared with conventional FCC units. Developed by Bar-Co and now offered by UOP it has been operating since 1994. 

They began reduced crude cracking experimentation in a small 12,000 barrel per day (B/D) Fluid Catalytic Cracking (FCC) operating unit at Louisville, Ky. The RCC process was born from these goals, concepts and a small operating unit. The development and attributes of this process have been described in a number of articles and patents (1-6). 

Wilson, J.W. (1997) Fluid Catalytic Cracking-Technology and Operation, PennWell Publishing Company, Tulsa, OK. 

Sadeghbeige, R. Fluid Catalytic Cracking Handbook Design, Operation and Troubleshooting of FCC Facilities. Houston Gulf Pubbshing Company, 2000. 

The fluid catalytic cracking (FCC) is a very dynamic nnit that is typically the major conversion process in a refinery. Proper modeling and nnderstanding of unit capabilities represents a tremendons opportunity to improve the overall nnit operation and minimize unit emissions. The combustion chemistry in the FCC regenerator that produces environmental pollntants is extremely complex as nnmerons interactions and reactions occnr between the various chemical species. 

Table 7 shows the yield distribution of the C4 isomers from different feedstocks with specific processing schemes. The largest yield of butylenes comes from the refineries processing middle distillates and from olefins plants cracking naphtha. The refinery product contains 35 to 65% butanes olefins plants, 3 to 5%. Catalyst type and operating severity determine the selectivity of the C4 isomer distribution (41) in the refinery process stream. Processes that parallel fluid catalytic cracking to produce butylenes and propylene from heavy cmde oil fractions are under development (42). 

Figure 1731. Fluidized bed reactor processes for the conversion of petroleum fractions, (a) Exxon Model IV fluid catalytic cracking (FCC) unit sketch and operating parameters. (Hetsroni, Handbook of Multiphase Systems, McGraw-Hill, New York, 1982). (b) A modem FCC unit utilizing active zeolite catalysts the reaction occurs primarily in the riser which can be as high as 45 m. (c) Fluidized bed hydroformer in which straight chain molecules are converted into branched ones in the presence of hydrogen at a pressure of 1500 atm. The process has been largely superseded by fixed bed units employing precious metal catalysts (Hetsroni, loc. cit.). (d) A fluidized bed coking process units have been built with capacities of 400-12,000 tons/day.

The feeds to these types of units are usually atmospheric and vacuum residua. The products include feeds for the production of transportation fuels, fuel oils, olefins, etc. However, the operating conditions of the reactor, whether it is a fluid catalytic cracking unit or a fixed-bed unit, is dependent upon the desired product slate and the properties of the feed. 

Sadeghbeigi, R. 1995. Fluid Catalytic Cracking Design, Operation, and Troubleshooting of FCC Facilities. Gulf Publishing Company, Houston, TX. 

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