Catalytic cracking reactors

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]. 

Figure 7.7b shows the essential features of a refinery catalytic cracker. Large molar mass hydrocarbon molecules are made to crack into smaller hydrocarbon molecules in the presence of a solid catalyst. The liquid hydrocarbon feed is atomized as it enters the catalytic cracking reactor and is mixed with the catalyst particles being carried by a flow of steam or light hydrocarbon gas. The mixture is carried up the riser and the reaction is essentially complete at the top of the riser. However, the reaction is accompanied by the deposition of carbon (coke) on the surface of the catalyst. The catalyst is separated from the gaseous products at the top of the reactor. The gaseous products leave the reactor... 

Fluidized catalytic cracking reactors, called cat crackers or FCC reactors, are one of society s most important large-scale reactors. On an average, each such... 

While these techniques have been applied to energy-related processes such as heat-integrated distillation columns and fluid catalytic cracking reactors, there is still extensive research required before the concept of plant design/control is reduced to practice. 

Buyan, Frank M., and Ross, Mark S. Fluid catalytic cracking reactor multi-feed nozzle system, USP 4650566 (1987) Campbell, H. W., and Hurn, E. J. Circulating Fluidized Bed Combustion on Stream at California Portland Cement Company, Coal Technology (Houston), 8th (3-4), p. 19 (1985). 

The low thermal conductivity of the molten polymers and their extremely high viscosity are the major problems for the catalytic cracking reactor design. The most widely used reactor systems have been ... 

Table 6.9 Product yield at the outlet of the catalytic hydrolysis reactor and the catalytic cracking reactor in the pilot-scale plant...

What are typical operating conditions (temperature, pressure) of a catalytic cracking reactor used in petroleum refining ... 

Figure 1.9 Industrial reactors (a) ammonia reactor and (b) fluidized-bed catalytic cracking reactor.

Typical modem catalytic cracking reactors operate at 480-550°C and at relatively low pressures. At first, natural silica-alumina clays were used as catalysts, but by the mid-1970s, zeolites and molecular sieve-based catalysts were used. Zeolite catalysts give more selective yields of products, while reducing the formation of gas and coke. 

N V Dewachtere, G F Froment, I Vassalos, N Markatos, N Skandalis. Advanced modeling of Riser-type catalytic cracking reactors. Applied Thermal Engineering, 17, 8-10, 837-844, 1997. 

Fl ld. A typical catalytic cracking reactor used in petroleum refining operates at 88S-1020 F and 10-30 psig. Chemical Process Industries. R.C. Shreve and JA. Brink. Jr.. 4th ed.. New York - McGraw - Hill Book Co.. Inc., 1977. p. 675. 

Description The DCC process overcame the limitations of conventional fluid catalytic cracking (FCC) processes. The propylene yield of DCC is 3-5 times that of conventional FCC processes. The processing scheme of DCC is similar to that of a conventional FCC unit consisting of reaction-regeneration, fractionation and gas concentration sections. The feedstock, dispersed with steam, is fed to the system and contacted with the hot regenerated catalyst either in a riser-plus fluidized dense-bed reactor (for DCC-I) or in a riser reactor (for DCC-II). The feed is catalytically cracked. Reactor effluent proceeds to the fractionation and gas concentration sections for stream separation and further recovery. The coke-deposited catalyst is stripped with steam and transferred to a regenerator where air is introduced and coke on the catalyst is removed by combustion. The hot regenerated catalyst is returned to the reactor at a controlled circulation rate to achieve the heat balance for the system. 

Combined Pressure and Temperature Loads During the Operation of a Reactor. The reactor considered here is a fluid catalytic cracking reactor [5-7] its fundamental design is shown in Figure 5.9. The materia) is 15 Mo 3. Reactors of this type are used in petrochemical plants for the fission of heavy hydrocarbons. 

The feed to the catalytic cracking reactor may be any distilled fraction, atmospheric or vacuum-distilled, that is to be reduced in molecular weight. Usually, it is a fraction with an initial boiling point above 670 K since more volatile materials can be processed into gasoline. 

A major application of fluidized bed technology is to be found in the catalytic-cracking reactor, or Cat Cracker , which lies at the heart of the petroleum refining process. Here, the catalyst particles (which promote the breakdown of the large crude petroleum molecules into the smaller constituents of gasoline, diesel, fuel oil, etc.) are fluidized by the vaporized crude oil. An unwanted by-product of the reactions is carbon, which deposits on the particle surfaces, thereby blocking their catalytic action. The properties of the fluidized state are further exploited to overcome this problem. The catalyst is reactivated continuously by circulating it to another bed, where it is fluidized with air in which the carbon burns... 

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