FCC cycle oils

Crude oil typically contains little to no olefinic compounds. Through refining and processing, however, olefins are produced and become a part of various crude oil fractions. Olefins can be found in thermally cracked and catalytically cracked gasoline fractions as well as in FCC cycle oils and coker gas oils. For this reason, it is not unusual for finished gasoline and distillate blends to contain a high-olefin-content stream. 

Blend with higher-specific-gravity fuel components such as high-aromatic-content heating oil or stabilized FCC cycle oil. These components will improve fuel BTU ratings. 

May contain a high concentration of FCC cycle oil, vacuum gas oil, or coker gas oil... 

Fuel could be blended with low-cetane-number components such as FCC cycle oil... 

FCC cycle oil containing unsaturated compounds is blended into fuel... 

For the light cycle oil from the base FCC operation, a correlation predicts the component mol fractions based on various properties computed by the FCC simulator. These properties include density, molecular weight, and percent carbon as aromatic ring and cycloparaffin ring. The correlation is based on mass spectrometer data on FCC cycle oils. 

Vacuum residium can be a fuel oil product after FCC cycle oil is added to reduce its viscosity. To feed the light cycle oil to the hydrocracker, the vacuum residium can be fed to a visbreaker for viscosity reduction. Alternatively, the vacuum residium may be fed to a coker for conversion to light products and coke. 

FCC cycle oils are typically high in aromatic content and have low cetane number (10-20). Hydrotreating or hydrocracking of these products and recycling them back to FCC to increase... 

Antimony-based passivation was introduced by Phillips Petroleum in 1976 to passivate nickel compounds in the FCC feed. Antimony is injected into the fresh feed, usually with the help of a carrier such as light cycle oil. If there are feed preheaters in the unit, antimony should be injected downstream of the preheater to avoid thermal decomposition of the antimony solution in the heater tubes. 

Heavy fractions (e.g., vacuum gas oils) and residues HDP might involve both, hydrotreatment and hydrocracking operations. HDT, in this case, is a feed pretreatment, for preparation to another process unit, which might be a HCK unit. This process combination, HDT-HCK can be used on Cycle Oil (FCC, coker), VGO (SR and coker) and SR residues (atmospheric and vacuum). It can be carried out in a single reactor with more than one catalyst, or in more than one reactor. 

Among the classes of feedstock processed in the hydrocracker the most highly aromatics feed are light cycle oils produced in the FCC unit Once formed by cyclization and the hydrogen transfer mechanism discussed above, they accumulate in the product due to the absence of a metal function in the FCC catalyst and adequate hydrogen in the process environment. They are typically sold as low-value fuel oil, or hydrotreated to reduce sulfur content and improve their quality as diesel blend stocks. Another approach to upgrade their value even further... 

Maximizing FCC Light Cycle Oil by Heavy Cycle Oil Recycle... 

In steady-state FCC operation with heavy cycle oil (HCO) recycling, it is conceivable that some hydrocarbon molecules could go through the riser multiple times. We developed a two-pass scheme that combines the Davison circulation riser (DCR) and advanced cracking evaluation (ACE) unit to simulate the recycling operation. 

For comparative purposes the typical weight percentage yields for a DCC unit, an FCC unit and a steam cracker are shown in Table 8.1. Propylene yields from the DCC unit are considerably higher than those from an FCC nnit. The DCC mixed C4s stream also contains increased amounts of bntylenes and iso-C4s as compared to an FCC. These high olefin yields are achieved by deeper cracking into the aliphatic components of the initially prodnced naphtha and life cycle oil (LCO). 

Cycle Oil. Heavier, distillate range compounds formed during FCC processing can accumulate within the FCC fractionator. The primary fraction is called light cycle oil (LCO) and contains high percentages of monoaromatic and diaromatic compounds plus olefins and heavier branched paraffins. Unhydrotreated LCO is often quite unstable and has a very low cetane number. For this reason, it is blended into diesel fuel in controlled amounts. Heavy cycle oil and heavy naphtha are additional side cuts that can be produced. These streams can be pumped around to remove heat from the fractionator, used to supply heat to other refinery units, or used as low-quality blendstock component. 

FCC Residual Heavy Cycle Oil Slurry Oil Decant Oil Clarified Oil - This heavy... 

For all of the hydrocracker operations, the feed properties are those of the heavy naphtha from the base crude mix blended with a specified fraction of light cycle oil from the base FCC operation. For all of the motor reformer operations, the feed properties are those of the motor naphtha from the base crude mix blended with heavy hydrocrackate from the base hydrocracker operation. For all of the BTX reformer operations, the feed properties are those of the BTX naphtha from the base crude mix blended with light hydrocrackate from the base hydrocracker operation. Finally, for each process unit, the process simulator computes the change in plant performance associated with a fixed perturbation of each feed property about the base operation. 

Part or all of three FCC products heavier than gasoline can be recycled from the fractionator back to the reactor the light cycle oil which at Toledo is a prime hydrocracker feed, the heavy cycle oil which is usually recycled, and the bottoms or slurry oil, part of which must be recycled to return entrained catalyst to the unit. The program offers six recycle options. For any option, the user specifies five out of the following eight recycle variables ... 

When the FCC simulator was linked to the preprocessor and tested on alternate operations and feed perturbations, it was discovered that the simulator would sometimes fail to converge in either the recycle loop or the conversion per pass loop. In case this happens, the user can change the initial estimates of the final boiling point of the heavy cycle oil and the conversion per pass for the base or any alternate FCC operation. To assist the user in selecting new estimates, the preprocessor prints out the following whenever the FCC simulator fails to converge ... 

The feed to the hydrocracker consists of the heavy naphtha cut from the base crude mix and light cycle oil from the base FCC operation. The hydrocracker simulator requires a description of each of these feeds in terms of the hydrocarbon components shown in Table I. Since these components are not directly measured in the crude assay nor are they predicted by the FCC simulator, special techniques were developed to estimate them from available data. 

In FCC, the conversion is usually defined as the yield in gasoline, LPG and ftielgas, but in this study, the conversion of an experiment is defined as the amount of heavy cycle oil (HCO) converted. This was done because the feed consists only of HCO and thus LCO would be a product. The conclusions drawn in this paper are not affected by this definition of conversion. 

Fluid Catalytic Cracking (FCC) is one of the main industrial catalytic processes, in which heavy hydrocarbons are converted into lighter hydrocarbons. The main products are gasoline and light cycle oil. The reactions are carried out in an entrained flow reactor, in which the... 

---