Process for converting a vacuum tower bottoms stream

Inactive Publication Date: 2016-04-28
UOP LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a process for processing a bottom stream from a vacuum tower. The process includes a first cracking zone to produce a converted stream and an unconverted stream, followed by a second cracking zone to produce a second converted stream and a pitch stream. The first cracking zone operates at a higher pressure than the second cracking zone. The converted streams can include gas oil. The process can also include monitoring the conversion through the use of a gas chromatograph method. The invention also includes a method for reducing the viscosity of the bottom stream by passing it through a visbreaking reactor and a slurry hydrocracking reactor. The invention also includes a method for increasing the conversion of the bottom stream by passing it through a visbreaking reactor and a slurry hydrocracking reactor.

Problems solved by technology

The variety of the physical properties of feed stocks to the slurry hydrocracking unit can also create issues.
For example, a vacuum column bottoms stream from a Light Arabian crude oil may have a viscosity of about 0.0019 m / s2 (1900 cSt) at 100° C., while a vacuum column bottom stream from a Heavy Arabian crude oil may have a viscosity of about 0.047000 m / s2 (47000 cSt) at 100° C. If the feed to the hydrocracking reactor becomes more viscous, handling issues can arise.
The high temperature can create storage problems for the effluent.

Method used

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  • Process for converting a vacuum tower bottoms stream
  • Process for converting a vacuum tower bottoms stream

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Embodiment Construction

[0021]As mentioned above, one or more processes have been invented for processing a vacuum tower bottom stream. In the processes two different cracking zones are used, preferably a first zone includes a visbreaking reactor and a second zone includes a slurry hydrocracker reactor downstream from the visbreaking reactor. Unlike slurry hydrocracking reactors, visbreaking reactors are relatively inexpensive. Thus, it would be less costly for a refiner to include a visbreaking reactor. Additionally, such process may provide for higher overall conversion of the feedstock without increasing the severity of the slurry hydrocracker operation. For example, to achieve a desired 95% conversion of the 524° C.+ (975° F.+) material in the vacuum column bottoms (or vacuum reside), a slurry hydrocracker unit downstream of a visbreaking reactor (operating at 25% conversion, as discussed below,) would have to operate at 90% conversion. Such process may also enable the design of a smaller slurry hydroc...

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Abstract

A process for improving a recovery from a bottoms stream from a vacuum tower. The bottom stream is passed to a first cracking zone and unconverted material from the first cracking zone is passed to a second cracking zone. The first cracking zone may include a visbreaking reactor. The second cracking zone may include a slurry hydrocracking reactor.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to a process for converting a stream from the bottom of a vacuum tower, and more particular to a process using two cracking zones to increase the recovery from the stream and improve the handling of same.BACKGROUND OF THE INVENTION[0002]Thermal cracking of hydrocarbons can achieve a high conversion of heavy feed stocks, such as vacuum residues, to lower boiling, more valuable distillate products. However, a portion of the product can remain after vacuum distillation. The remaining portion typically comprises unconverted pitch that may have a boiling point greater than about 500° C. The pitch can be sent to a slurry hydrocracking unit to recovery some of the hydrocarbons therefrom.[0003]Due to the cost of the slurry hydrocracking reactors, refiners seek to achieve the maximum conversion of the vacuum residues. To meet the desired conversion levels, as well as to provide mesophase (or coke and coke precursor) free conditions...

Claims

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Application Information

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IPC IPC(8): C10G69/06
CPCC10G69/06C10G7/06C10G9/007C10G47/26
InventorSTANDING, CHRISTOPHER LEPINESUN, PINGYOKOMIZO, GRANTWILSON, JAMES MALCOLM ROBERT
OwnerUOP LLC