Efficiency fluid catalytic cracking

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. 

In the S W fluid catalytic cracking process (Figure 8-15), the heavy feedstock is injected into a stabilized, upward flowing catalyst stream whereupon the feedstock-steam-catalyst mixture travels up the riser and is separated by a high efficiency inertial separator. The product vapor goes overhead to the main fractionator (Long, 1987). 

Reboiled stripping is efficient for mixtures containing a significant amount of light and intermediate components. An example is the separation of C2 and C3 fractions from a hydrocarbon mixture issued from fluid catalytic cracking. The initial precooled mixture is sent to the top of a distillation column provided only with reboiler. The top product contains gases and light components stripped out... 

Oil and Gas Industry. One of the most important applications of a flow reactor system is to enable fluid catalytic cracking at an oil refinery. Only because long hydrocarbon molecule chains that remain after distillation of crude oil can be broken, or cracked, very efficiently in a fluidized bed reactor, can the world s demand for lighter hydrocarbon products such as gasoline or jet fuel, be satisfied. In addition, oil refineries employ a variety of other flow reactor systems to facilitate many of their other processes. Catalytic reforming, to increase gasoline quality, is done both in packed and fluidized bed reactors. 

Improvements in chemical processes are very often based on the discovery or development of new catalysts or adsorbents. One particularly exciting example in the field of zeolite catalysis is the replacement of the formerly used amorphous silica-aliunina catalysts in fluid catalytic cracking (FCC) of vacuiun gas oil by rare earth exchanged X-type zeoUtes [1]. This resulted in considerably improved yields of the desired gasoUne and, hence, a much more efficient utilization of the crude oil. Fiuther examples are the introduction of zeolite HZSM-5 as catalyst in the synthesis of ethylbenzene from benzene and ethylene [2], for xylene isomerization [3] and for the conversion of methanol to high-... 

Carbon Monoxide. In the petroleum industry, the efficient operation of a fluid-catalytic-cracking unit produces gases rich in carbon monoxide. To reclaim the thermal energy represented by these gases, the fluid-catalytic-cracking unit can be designed to include a CO boiler that uses the CO as fuel to generate steam for use in the process. 

Fluid Catalytic Cracking 0.15 to 0.30 Higher feed rate Reduced AP across slide valves Reduced product quality giveaway Increased energy efficiency... 

In the last 10 years, as a result of more efficient operating methods, carbonate stress corrosion cracking has occurred in the fractionator overheads in fluid catalytic crackers. The problem is most severe at a pH greater than 9 and a carbonate concentration above 110 ppm. It has also occurred at a pH between 8 and 9 when the carbonate concentration is above 400 ppm. Therefore, most refiners are now specifying postweld heat treatment of carbon steel when such conditions are anticipated. 

Even more efficient processes were introduced later in the war. Mobil developed a moving bed process called Thermofor Catalytic Cracking and a new synthetic amorphous cracking catalyst (Ref. 1), while Exxon led a group of companies in developing fluid cat cracking. These processes provided the Armed Forces with plentiful supplies of 100 octane aviation fuel in the latter stages of World War II and they were a decisive element in the final Allied victory in Europe. 

On a graph of h tanh h vs. h we read that h = 0.94, and Fig. 6 tells us that for this value of h the fraction of surface available is 78%. This is in good agreement with experimental data on catalytic cracking since it predicts that fluid bed and fixed bed performance should be substantially the same. In other words, the cracking reaction is slow enough to use 30 A. unit pores in J -inch pellets with about 80% efficiency. 

In the 1930 s, Standard Oil of New Jersey (now Exxon) attempted to license the Houdry technology but were discouraged by the high license fee set by Houdry of 50,000,000 (13, 14). This fee, adjusted via the Consumer Price Index, is over 750,000,000 in today s currency This led the Standard Oil Co. of New Jersey (Jersey) to develop new catalytic cracking technology. Their initial work was based upon the fixed bed concept but was quickly refocused upon the more efficient fluid bed design to avoid the inefficiencies and complexities of the cyclic fixed beds (15). 

Economic efficiency of waste plastics processing depends on the methods of their selection and preparation for processing as well as the cost of thermal or catalytic treatment, i.e. the cost of investment and exploitation of the cracking plant. For instance the main characteristic of fluid-bed reactors is the possibility of exploitation of large-scale units (at least 50000 tons or more per year), low cost of exploitation, but accompanied by large investment and feed delivery costs. And on the other hand, smaller reactors can be built on a smaller scale, a few thousand tons per year output, lower investment costs and lower feed deliveries (processing of local wastes in limited area), but operated with larger exploitation costs. 

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