Cracking processes fluid coking

There are two major commercial thermal cracking processes, delayed coking and fluid coking. Flexicoking is a fluid coking process in which the coke is gasified with air and steam. The resulting gas mixture partially provides process heat. 

In the fluid coking process, part of the coke produced is used to provide the process heat. Cracking reactions occur inside the heater and the fluidized-bed reactor. The fluid coke is partially formed in the heater. Hot coke slurry from the heater is recycled to the fluid reactor to provide the heat required for the cracking reactions. Fluid coke is formed by spraying the hot feed on the already-formed coke particles. Reactor temperature is about 520°C, and the conversion into coke is immediate, with... 

Fluid coke is produced in a fluidized bed reactor where the heavy oil feedstock is sprayed onto a bed of fluidized coke. The oil feedstock is cracked by steam introduced into the bottom of the fluidized bed reactor. Vapor product is drawn off the top of the reactor while the coke descends to the bottom of the reactor and is transported to a burner where a portion of the coke is burned to operate the process. Fluid coke reactors are operated at about 510 - 540°C (950 - 1000 F). Flexicoke is a variant cm fluid coke, where a gasifier is added to the process to increase coke yields. Fluid coker installations tend to have yields that are lower than delayed coker installations, while flexicoker installaticms have yields that can be significantly greater than delayed coker installations. Fluid cokers produce layered and non-layered cokes. Both delayed and fluid coke installations produce amorphous, incipient, and mesophase cokes with the amorphous cokes having higher volatility and mesophase cokes having the lowest volatility. 

Catalytic Processes. A second group of refining operations which contribute to gas production are the catalytic cracking processes, such as fluid-bed catalytic cracking, and other variants, in which heavy gas oils are converted into gas, naphthas, fuel oil, and coke (5). 

Refinery Production. Refinery propylene is formed as a by-product of fluid catalytic cracking of gas oils and, to a far lesser extent, of thermal processes, eg, coking. The total amount of propylene produced depends on the mix of these processes and the specific refinery product slate. For example, in the United States, refiners have maximized gasoline production. This results in a higher level of propylene production than in Europe, where proportionally more heating oil is produced. 

The most dominant catalytic process in the United States is the fluid catalytic cracking process. In this process, partially vaporized medium-cut petroleum fractions called gas oils are brought in contact with a hot, moving, freshly regenerated catalyst stream for a short period of time at process conditions noted above. Spent catalyst moves continuously into a regenerator where deposited coke on the catalyst is burnt off. The hot, freshly regenerated catalyst moves back to the reactor to contact the hot gas oil (see Catalysts, regeneration). 

Fluid coking a continuous fluidized solids process that cracks feed thermally over heated coke particles in a reactor vessel to gas, liquid products, and coke. 

The modem gasolines are produced by blending products from cmde oil distillation, that is, fluid catalytic cracking, hydrocraking, reforming, coking, polymerization, isomerization, and alkylation.Two clear examples of the possible use of solid-acid catalysts in refining processes are the isomerization of lineal alkanes and the alkylation of isobutene with butanes. In both these cases, and due to the octane... 

This process is used to produce light gases, naphtha, distillate fuel, heavy fuel oil, and petroleum coke by cracking heavy residual products such as atmospheric and vacuum resids. Both delayed coking and fluid coking processes are utilized. 

When compared to the delayed coking process, higher yields of liquid products are typically produced by fluid coking. This continuous process utilizes a fluidized reaction zone of hot coke particles held in motion by steam. The coke particles are first heated in a burner to temperatures ranging from 1,100°F to 1,200°F (593.3°C to 648.9°C). The hot coke particles then are blown into the reactor by steam. The residual fuel is fed into the reactor and cracks on the hot surface of the fluidized coke particles. 

The fluid coking process accomplishes ihe coking operation in a continuous manner. Feed is sprayed into a fluid bed of hoi coke in a coking reactor. Steam introduced inio the bottom of the reactor provides the fluidization energy. The cracked products are quenched in an overhead scrubber and then go to Ihe fractionator. The coke is deposiled on Ihe particles in the reactor, which commute with a heater vessel in which a portion of the coke is burned to heal up the reluming coke particles to supply the energy for the coking reaction. 

The ET-II process is a thermal cracking process for the production of distillates and cracked residuum for use as a metallurgical coke and is designed to accommodate feedstocks such as heavy oils, atmospheric residua, and vacuum residua (Kuwahara, 1987). The distillate (referred to in the process as cracked oil) is suitable as a feedstock to hydrocracker and fluid catalytic cracking. The basic technology of the ET-II process is derived from that of the original Eureka process. 

D. L. Trimm in Fundamental Aspects of the Formation and Gasification of Coke in L. F. Albright, B. L. Crynes, W. H. Corcoran (eds.), Pyrolysis Theory and Industrial Practice , Academic Press, New York, 1983 L. F. Albright, B. L. Crynes, W. H. Corcoran (eds.), Pyrolysis Theory and Industrial Practice , Academic Press, New York, 1983 T. J. Ford, Ind. Eng. Chem. Fundam., 25, 240, 1986 Coastal Isobutane Cracking Process developed by Foster Wheeler P. B. Venuto and E. T. Habib, Fluid Catalytic Cracking with Zeolite Catalysts , Marcel Dekker, New York, 1979... 

Chemical composition of waste plastic cracking products depends on shares of the individual polymers (PE, PP, PS) in the feed and process parameters. This fact decides the technological application of the final products. Important products of the cracking process, both petroleum fractions and waste plastics, are coke residues. Coke residue yield increases considerably, up to 10 wt%, in cracking of municipal and industrial waste plastics since they contain various inorganic impurities and additives. It can be applied as solid fuel, like brown coal. In the fluid cracking the solid residue is continuously removed from the process by combustion in a regenerator section. 

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