Integrated Solvent Deasphalting and Slurry Hydrocracking Process

Abstract

Integrated slurry hydrocracking (SHC) and coking methods for making slurry hydrocracking (SHC) distillates are disclosed. Representative methods involve passing a slurry comprising a deasphalted oil (DAO) produced in a solvent deasphalting (SDA) process, optionally with recycled SHC gas oil and recycled SHC pitch, and a solid particulate through an SHC reaction zone in the presence of hydrogen to obtain the SHC distillate. Recovery and recycle of SHC gas oil and pitch from the SHC effluent improves the overall conversion to naphtha and distillate products and decreases catalyst requirements.

Description

FIELD OF THE INVENTION[0001]The present invention relates to methods for preparing distillate hydrocarbons using slurry hydrocracking (SHC) to upgrade high-boiling or heavy hydrocarbons obtained from refinery operations and particularly solvent deasphalting (SDA). The integration of SHC with SDA and optionally other processes such as crude oil fractionation and / or hydrotreating may be used to obtain a high quality (e.g., high API gravity and / or low sulfur) distillate.DESCRIPTION OF RELATED ART[0002]Solvent deasphalting (SDA) generally refers to refinery processes that upgrade hydrocarbon fractions using an extraction process in the presence of a solvent. The hydrocarbon fractions are often obtained from the distillation of crude oil, and include hydrocarbon residues (or resids) or gas oils from atmospheric column or vacuum column distillation. Solvents used in SDA are typically lower-boiling paraffinic hydrocarbons such as propane, butane, and their mixtures, having the ability to e...

AI Technical Summary

Benefits of technology

[0008]Aspects of the invention relate to the finding that slurry hydrocracking (SHC) can be effectively integrated with other refining processes and particularly solvent deasphalting (SDA), hydrotreating, and / or crude oil fractionation to produce a high value distillate stream while recycling low-value gas oils, preferably to extinction, as well as at least a portion of the SHC pitch. SHC is generally known in the art for its ability to convert vacuum column residues to lighter products. However, it has now been discovered that the use of a deasphalted oil (DAO) from SDA as a heavy hydrocarbon feedstock component or incremental feed to SHC results in operating synergies having commercially important advantages.

[0010]The use of a heavy hydrocarbon feedstock comprising DAO may be combined with other SHC process features to obtain additional benefits. For example, recycling (e.g., to extinction) a portion of an SHC pitch and / or an SHC gas oil recovered from the SHC effluent allows for the complete or essentially complete overall conversion of these recycle streams (as well as the DAO) to the higher value SHC distillate. Moreover, the high content of polar aromatic compounds (e.g., mono- and multi-ring aromatics) in the recycle SHC gas oil, such as vacuum gas oil (VGO) obtained from vacuum column fractionation of a liquid product recovered from the SHC effluent, reduces the catalyst requirement of SHC. Without being bound by theory, it is believed that these recycled aromatics help solubilize asphaltenes in SHC recycle streams and thereby prevent the formation of precipitated agglomerates of asphaltenes and the solid particulate catalyst, leading to coking in the reactor or increased catalyst requirements to limit this coking. The recycling of SHC pitch can also help minimize make-up requirements, as this pitch contains catalyst with activity comparable to that of fresh catalyst.

[0011]Overall, the use of DAO as a component of the heavy hydrocarbon feedstock in SHC results in a surprisingly high conversion of this component (both on a per-pass and overall basis). Compared to conventional SHC, processing a vacuum column residue from crude oil fractionation in the absence of DAO, integrated processes according to the present invention have significantly reduced catalyst requirements, smaller reactor sizes, and / or lower reactor operating pressures. Relative to fixed bed or ebullating bed hydrocracking processes, the catalyst make-up rates of SHC processes described herein are surprisingly less adversely impacted by the high metals content of the DAO feed components, known to deactivate catalysts used in these conventional conversion processes. In fact, the types and amounts of contaminants in DAO products renders these streams difficult, in general, to further upgrade using FCC, hydrocracking, or hydrotreating.

[0014]In other embodiments, an integrated SDA / SHC process is combined with hydrotreating of the SHC distillate. As a result of the low (or non-existent) net yield of gas oil products such as VGO, due to recycling of heavy-boiling fractions back to the SHC reaction zone, the hydrotreated distillate has a sufficiently high API gravity (e.g., at least about 20°), making it attractive for blending into a synthetic crude oil that is transported via a pipeline. Thus, the hydrotreated distillate, or even the SHC distillate without hydrotreating, may be obtained as a high quality transportation fuel blending component with only a minor amount or essentially no hydrocarbons boiling at a temperature representative of gas oils (e.g., greater than about 343° C. (650° F.)). The integration of SHC with an existing refinery hydrotreating process, conventionally used for sulfur- and nitrogen-containing compound removal from distillates, may involve hydrotreating a recovered SHC distillate product in conjunction with a straight-run distillate obtained from crude oil fractionation and / or other refinery streams. This integration may advantageously reduce overall capital costs of the complex. As discussed above, the integration of SDA with SHC, optionally hydrotreating, and optionally other conventional refinery operations has the potential to provide significant benefits in terms of improved processing efficiency and product yields, reduction or elimination of low-value refractory byproducts, and / or the associated capital cost reduction.

Problems solved by technology

The DAO products from SDA processes, and particularly those processes that are operated with relatively high recoveries of DAO and low recoveries of pitch, have high levels of metal contaminants and Conradson carbon residue, making such DAO products difficult to upgrade with conventional FCC or hydrocracking, using either a fixed bed or ebullating bed of catalyst.

In fact, the types and amounts of contaminants in DAO products renders these streams difficult, in general, to further upgrade using FCC, hydrocracking, or hydrotreating.

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