Multiple hydroprocessing reactors with intermediate flash zones
AssigneeChevron U.S.A. Inc.
InventorsArthur J. Dahlberg, Jerome F. Mayer
Life of this patent
Estimating the term…
Abstract
The instant invention comprises a hydroprocessing method having at least two stages. The first stage employs a hydroprocessing catalyst which may contain hydrotreating catalyst, hydrocracking catalyst, or a combination of both. The second stage is limited to hydrocracking. Conversion in the second stage may be improved by the addition of multiple reaction zones for hydrocracking, with flash separation zones between the stages. Middle distillate yield is thereby increased and the volume of the recycle stream is reduced. This invention reduces the need for equipment which would normally be required for a large recycle stream.
Claims14
The hydroprocessing method of the instant invention, which has at least two reaction stages, comprises the following steps:
- (a) passing a hydrocarbon feed into a first reaction stage, which is maintained at hydroprocessing conditions, where it is contacted with a catalyst in a fixed bed and at least a portion of the feed is converted;
- (b) combining the effluent of step (a) with product material from a second reaction stage and passing the combined stream to a separation zone;
- (c) separating the stream of step (b) into an unconverted liquid effluent and at least one converted stream comprising products having a boiling point below that of the feed;
- (d) passing the unconverted liquid effluent from step (c) to a second reaction stage, said stage comprising a plurality of reaction zones, wherein each zone is maintained at hydrocracking conditions and separation occurs between each zone;
- (e) contacting the feed in the first reaction zone of step (d) with a catalyst in a fixed bed, thereby converting at least a portion of the feed;
- (f) separating the effluent of step (e) into an unconverted liquid effluent, and a hydrogen-rich converted stream;
- (g) recycling the hydrogen-rich converted stream of step (f) to combine with the effluent of step (a);
- (h) passing the unconverted liquid effluent from step (f) to a second reaction zone of the second stage, the zone being maintained at hydrocracking conditions;
- (i) contacting the feed in the second reaction zone of step (h) with a catalyst in a fixed bed, thereby converting at least a portion of the feed;
- (j) fractionating the effluent of step (i) to produce gas, naphtha, and one or more middle distillate product streams, unconverted material being recycled to step (d).
Dependencies are inferred from the claim text.