Catalytic cracking commercial development

Dynacracking A petroleum cracking process which combines the best features of the "catalytic cracking and Thermal cracking processes. It converts heavy oil feedstocks to fuel gas, gasoline, and fuel oil. No catalyst is used. Developed in the 1950s by Hydrocarbon Research, but not commercialized. 

Deep catalytic cracking (DCC) is a commercially proven FCC process for selectively cracking a wide variety of feedstocks to light olefins, particularly propylene. Innovations in catalyst development, operational severity, and anticoking conditions. 

With the financial and technical help of those two oil companies, extensive development work on the catalytic cracking process was carried out on a laboratory and semiplant scale. This included the study of catalysts and the process variables, as well as the development of new engineering concepts which led to the first commercial application of this process in 1936. 

In present catalytic cracking processes the production of gasoline is accompanied by the formation of substantial amounts of coke, as well as the production of hydrogen and light hydrocarbons. As the control of the combustion of coke was the main problem facing the commercial development, the effects of variables are conveniently expressed in terms of coke formation in the following discussion. 

Prior to the development of the catalytic cracking process, aviation gasoline was produced by adding tetraethyllead to blends of commercial iso-octane (2,2,4-trimethyl-pentane) and selected straight-run petroleum fractions. 

The commercial development of catalytic cracking made available additional supplies of blending stocks having the necessary requirements of volatility, stability, and antiknock value. At the same time, by-product isobutane and butylenes provided charging stocks for the newly developed alkylation processes. 

Commercial Development of Fixed-Bed Process. From the above process considerations it became obvious that the capacity of a commercial unit, and its economic value, were closely related to its ability to burn coke. Indeed, most of the design problems associated with catalytic cracking have been centered around the question of catalyst regeneration. To obtain the most favorable economic return from a 10,000-barrel-per-day unit, it was designed to burn approximately 6000 pounds per hour of coke. This coke yield represents approximately 5% by weight of the charge. 

It is gratifying to the technicians of the Houdry Process Corp., Socony-Vacuum Oil Co., and Sun Oil Co. that a number of these engineering features developed in connection with the first commercial applications of fixed-bed catalytic cracking have proved of considerable interest to other industries where they are currently used. 

A model for the riser reactor of commercial fluid catalytic cracking units (FCCU) and pilot plants is developed This model is for real reactors and feedstocks and for commercial FCC catalysts. It is based on hydrodynamic considerations and on the kinetics of cracking and deactivation. The microkinetic model used has five lumps with eight kinetic constants for cracking and two for the catalyst deactivation. These 10 kinetic constants have to be previously determined in laboratory tests for the feedstock-catalyst considered. The model predicts quite well the product distribution at the riser exit. It allows the study of the effect of several operational parameters and of riser revampings. 

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