Resid catalytic cracking

Resid catalytic cracking (RFCC) (carbon rejection)... 

Catalytic cracking is a key refining process along with catalytic reforming and alkylation for the production of gasoline. Operating at low pressure and in the gas phase, it uses the catalyst as a solid heat transfer medium. The reaction temperature is 500-540°C and residence time is on the order of one second. 

Solvent extraction may also be used to reduce asphaltenes and metals from heavy fractions and residues before using them in catalytic cracking. The organic solvent separates the resids into demetallized oil with lower metal and asphaltene content than the feed, and asphalt with high metal content. Figure 3-2 shows the IFP deasphalting process and Table 3-2 shows the analysis of feed before and after solvent treatment. Solvent extraction is used extensively in the petroleum refining industry. Each process uses its selective solvent, but, the basic principle is the same as above. 

The CFB catalytic cracking reactor plays an important role in the petroleum industry because of its better gas-solids contact and narrow residence time distribution, but its non-uniform radial flow structure and the extensive backmixing of gas and solids lead to a lower conversion rate and poorer selectivity to desired intermediate products [14]. 

This type of reactor aims to challenge fast fluidization with its 1 to 10 second gas residence time as the prime reactor for the catalytic cracking of petroleum. The claim is that the higher cracking temperature and shorter residence time will give a very different—and better—distribution of reaction products. 

However, the use of short residence times with the catalyst placed in a more optimal position to insure better contact with the feedstock has resulted in the millisecond catalytic cracking (MSCC) unit that is used to process residua (Hydrocarbon Processing, 1998). The unit is flexible in terms of feedstock changes and the improved metals tolerance of the process allows the unit to handle a wide range of feedstocks. 

Gulf resid hydrodesulfurization process a process for the desulfurization of heavy feedstocks to produce low-sulfur fuel oils or catalytic cracking (q.v.) feedstocks. 

MSCC process a short-residence time process (millisecond catalytic cracking) in which the catalyst is placed in a more optimal position to insure better contact with the feedstock. 

Several hydrocarbon processes are available for upgrading resid hydrotreating, Fluid Catalytic Cracking (FCC), coking etc., some more capital intensive than others. The most widely prevalent process is the FCC process. Therefore any advances in processing resid in FCC units will have wide application. This paper deals with concepts for developments in resid cracking, particularly in resid FCC development, evaluation and application. 

P. O Connor, A.C. Pouwels and J.R. Wilcox "Evaluation of Resid FCC Catalysts" Symposium on Catalytic Cracking of Heavy Oils, paper 242E,... 

Fig. 18.19. Fluid catalytic cracking—UOP LLC. Combustor style is used to crack process gas oils and moderately contaminated resids, while the two-stage unit is used for more contaminated oils. (Source Hydrocarbon Processing, 2004 Refining Process Handbook. CD-ROM. September 2004 copyright 2004 by Gulf Publishing Co., all rights reserved.)...

Non-stationary operations have found large scale industrial application. An important classical example is catalytic cracking, where oil is exposed with a short residence time to a rapidly deactivating zeolitic catalyst, which is regenerated in a second step by removal of deposited coke. A novel non-stationary process is selective butane oxidation over a regenerable oxidation catalyst (see Chapter 2). Undoubtedly we will see more examples of this type of process, in which the proper catalytic step and the regeneration of the catalytic sites occur in different compartments under different conditions. A nice application involves... 

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