SEPARATOR VESSEL AND PROCESS OF USING SAME

Abstract

A separator for separating a hydroprocessed effluent and a process of using same. The separator vessel includes a scrubbing section in a tower to remove acid gases from the vapor that is separated in the separator and that passes upwards through the tower. A treated gas can be recovered from the separator. Additionally, a liquid hydrocarbon stream and a water stream, usually a sour water stream, can be recovered from the separator as well.

Description

FIELD OF THE INVENTION

This invention relates generally to a separator vessel, and more particularly to a separator vessel used to separate a portion of the reactor effluent from a hydroprocessing zone.

BACKGROUND OF THE INVENTION

Generally, there is an increasing trend among refiners to process heavier crude oils that contain high amounts of sulfur and nitrogen compounds. The feed obtained from such crude oils and subjected to a hydroprocessing process such as a kerosene hydrotreating, diesel hydrotreating, and vacuum gas oil (VGO) hydrotreating and hydrocracking processes can, in turn, also contain high amounts of sulfur and nitrogen compounds. The sulfur and nitrogen compounds are undesirable and therefore need to be removed or converted.

During the hydroprocessing of these feed streams, the sulfur and nitrogen compounds can be converted to hydrogen sulfide and ammonia, respectively, by the reacting the sulfur and nitrogen compounds with hydrogen. The resulting reactor effluent may therefore contain a high amount of hydrogen sulfide and ammonia.

In sufficient concentrations, the ammonia and hydrogen sulfide can combine to form ammonium bisulfide, which usually deposits in the reactor effluent condenser and can result in plugging this piece of equipment. Water can be added to prevent plugging of the exchanger by hindering the ammonium bisulfide salts from depositing in the effluent condenser.

Some of the hydrogen sulfide and ammonia will not combine in the reactor effluent material and, thus, not all of the hydrogen sulfide and ammonia will be removed by dissolving in the water stream. Thus, some hydrogen sulfide and ammonia can pass through the cold separator and into the recycle gas. Accordingly, the recycle gas is typically contacted with an amine solution in the downstream recycle gas scrubber. The hydrogen sulfide and ammonia absorbed by the amine, may be sent to an amine regenerator.

Hydroprocessing units typically include a cold high pressure separator located downstream of a reactor effluent air condenser. The hydrocarbon liquid, vapor, and sour water separate in the cold separator. The cold separator normally has a horizontal configuration to provide sufficient separation length for hydrocarbon liquid and water separation. The vapors from the cold separator can be passed to the recycle gas scrubber knock out drum and then to the recycle gas scrubber. In the recycle gas scrubber, hydrogen sulfide is removed from the recycle gas by contacting it with lean amine across a packed bed or trays. The treated recycle gas is then routed to the recycle gas compressor. Such a separator is disclosed, for example in U.S. Pat. Pub. No. 2014/0091009.

Remaining competitive in the hydroprocessing field requires an innovative approach to the design of each hydroprocessing unit. Each of the pieces of equipment described above requires a certain amount of plot space, a foundation, and piping to and from associated equipment all of which increases capital expenditures, as well as costs associated with installing same. Furthermore, additional pieces of equipment require more energy to operate.

Therefore, it would be desirable to minimize the amount of equipment required for such a hydroprocessing unit.

SUMMARY OF THE INVENTION

A new separator vessel and a process of using same been invented which combines the separate equipment pieces typically used in a hydroprocessing unit in an effective and efficient manner.

In a first aspect of the present invention, the present invention provides a device that may be characterized as a separator vessel for separating and treating a portion of an effluent stream. The vessel includes a body having a first end, a second end, a top, a bottom, and an inlet for an effluent stream. The inlet is disposed near the first end of the body. The vessel also includes a boot extending away from the bottom of the body. Finally, the vessel includes a tower extending away from the top of the body. The tower is disposed above at least a portion of the boot. The tower includes a scrubbing section configured to remove hydrogen sulfide from recycle gas within the body of the vessel.

In at least one embodiment of the present invention, the vessel also includes a chimney tray disposed in the tower between the body of the vessel and the scrubbing section of the tower. It is contemplated that the vessel also includes an outlet for rich amine associated with the chimney tray.

In some embodiments of the present invention, the vessel further includes an inlet for lean amine disposed in the tower above the scrubbing section.

In some embodiments of the present invention, a coalescer extends between the top of the vessel and the bottom of the vessel and is disposed between the first end of the vessel and the tower.

In various embodiments of the present invention, an outlet for a liquid hydrocarbon stream is disposed proximate the second end of the body.

In some embodiments of the present invention, the scrubbing section comprises at least one packed bed or tray.

In various embodiments of the present invention, the vessel includes an outlet for treated vapor disposed proximate a top of the tower.

In at least one embodiment of the present invention, an operating pressure of the vessel is approximately 40 to 180 Kg/cm².

In a second aspect of the invention, the present invention may be characterized as a separator vessel for separating a portion of an effluent stream into a vapor stream and a liquid stream and for treating the vapor stream within the vessel. The separator vessel comprises a body having a first end, a second end, a top, a bottom, and an inlet for an effluent stream, the inlet is disposed near the first end of the body. The separator vessel also includes a boot extending away from the bottom of the body, an outlet for a liquid hydrocarbon stream disposed proximate the second end of the body, and a tower extending away from the top of the body, the tower being disposed above at least a portion of the boot and including at least one packed bed or tray. The separator vessel also includes a second outlet for a scrubbed vapor stream disposed proximate a top of the tower.

In another aspect of the invention, the present invention may be characterized as a process for separating and treating a liquid effluent stream from a hydroprocessing zone by: passing a liquid effluent stream from a hydroprocessing zone to a separation zone; separating the liquid effluent stream into a liquid portion and a vapor portion in the separation zone, wherein the separation zone comprises at least one vessel comprising: a body having a first end, a second end, a top, a bottom, and an inlet for a hydrotreated effluent stream, the inlet disposed near the first end of the body; a boot extending away from the bottom of the body; and, a tower extending away from the top of the body, the tower disposed above at least a portion of the boot, wherein the tower includes a scrubbing section; and, removing hydrogen sulfide from the vapor portion of the liquid effluent stream within the at least one vessel.

In various embodiments of the present invention, the process also includes hydrotreating a feed stream in a hydrotreating zone to produce a hydrotreated stream. It is contemplated that the hydrotreated stream comprises the liquid effluent stream from a hydroprocessing zone. It is even further contemplated that the hydrotreated stream comprises a hydrotreated diesel stream, a hydrotreated kerosene, or a hydrotreated VGO stream.

In some embodiments of the present invention, the process also includes hydrocracking a feed stream in a hydrocracking zone to produce a hydrocracked stream. It is contemplated that the hydrocracked stream comprises the liquid effluent stream from a hydroprocessing zone.

In various embodiments of the present invention, the at least one vessel further comprises a chimney tray disposed in the tower between the body of the vessel and the scrubbing section of the tower.

In some embodiments of the present invention, the at least one vessel further comprises a demister extending between the top of the vessel and the bottom of the vessel and disposed between the first end of the vessel and the tower.

In at least one embodiment of the present invention, the at least one vessel further comprises an outlet for a liquid hydrocarbon stream disposed proximate the second end of the body.

In various embodiments of the present invention, the scrubbing section of the at least one vessel further comprises at least one packed bed or tray.

In one or more embodiments of the present invention, the at least one vessel further comprises an outlet for treated vapor disposed proximate a top of the tower.

In various embodiments of the present invention, the process further includes passing a lean amine stream into the tower of the at least one vessel.

In at least one embodiment of the present invention, the process also includes removing a sour water stream from the boot of the at least one vessel of the separation zone.

Additional objects, embodiments, and details of the invention are set forth in the following detailed description of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The drawings are exemplary of one or more embodiments of the present invention in which:

FIG. 1 shows a process flow diagram with a separator according to one or more embodiments of the present invention; and,

FIG. 2 shows a side cutaway view of a separator vessel according to various embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As mentioned above, a new separator vessel and process associated with same have been invented in which the recycle gas scrubber and the cold separator are combined. The vapor from the cold separator flows directly to a packed (or trayed) scrubbing section of the separator after passing through a chimney tray. Since there is no external piping to route the vapor, the chance of condensation of the vapor, on its way to the scrubbing section, is minimal Therefore, no knock out drum is needed in the unit. This eliminates the need for high pressure piping and a high pressure vessel for the refiner thereby reducing capital cost and plot space.

Accordingly, with reference the attached drawings, one or more embodiments of the present invention will now be described with the understanding that the described embodiments are merely preferred and are not intended to be limiting.

Referring to FIG. 1, a separation zone 11 having at least one separator vessel 10 receives a hydroprocessed effluent 12 from a hydroprocessing zone 14.

As will be appreciated, the hydroprocessing zone 14 can receive a feed stock 16 which can be any suitable kerosene, diesel, and/or heavy oil feed stock depending upon the type of hydroprocessing unit and unit configuration. Heavy oil feed stocks can include hydrocarbonaceous streams having components boiling above about 200° C., such as atmospheric gas oils, vacuum gas oil, reduced crude, and vacuum residuum, coker distillates, straight run distillates, solvent-deasphalted oils, pyrolysis-derived oils, high boiling synthetic oils, cycle oils, hydrocracked feeds, and cat cracker distillates. These hydrocarbonaceous feed stocks may contain from about 0.1 to about 4%, by weight, sulfur. Other suitable heavy oil feed stocks are disclosed in, e.g., U.S. Pat. No. 3,719,740.

Additionally, the feed stock can be combined with a hydrogen gas 18. The hydrogen gas 18 can include a recycled hydrogen gas as well as make-up hydrogen. Thus, other gases, such as methane, may be also present in smaller quantities, in addition to the hydrogen. The hydrogen gas 18 rate can be about 80 to about 1,700 normalized meter-cubed of hydrogen feed.

The hydroprocessing zone 14 can include any suitable hydroprocessing reactor 20 for conducting activity such as demetallizing, desulfurizing, denitrogenating, hydroisomerization, hydrotreating, and hydrocracking, including slurry hydrocracking. More than one hydroprocessing reactor 20 may be utilized.

The hydroprocessing reactor 20 can include at least one Group VIII metal, preferably iron, cobalt and nickel, on a high surface area support material, preferably alumina Other suitable hydrotreating catalysts include zeolitic catalysts, as well as noble metal catalysts where the noble metal can be at least one of palladium and platinum. The Group VIII metal is typically present in an amount of about 2 to about 20%, by weight, preferably about 4 to about 12%, by weight, based on the weight of the catalyst. The Group VI metal can be present in an amount of about 1 to about 25%, by weight, preferably about 2 to about 25%, by weight, based on the weight of the catalyst. Other catalysts and/or methods of manufacture are disclosed in, e.g., U.S. Pat. No. 8,747,653 and U.S. Pat. No. 3,719,740. The hydroprocessing conditions can include a temperature of about 290 to about 460° C., a pressure of about 3 to about 20 Kg/cm², and a liquid hourly space velocity of the fresh hydrocarbonaceous feed of about 0.1 to about 4 hr⁻¹. The hydroprocessed effluent 12 obtained from the hydroprocessing zone 14 may include one or more hydrocarbons, such as one or more C₁-C₃₀, and can be provided to the separator vessel 10.

In a preferred embodiment, the hydroprocessing reactor 20 comprises a hydrotreating reactor or hydrocracking reactor, and in a most preferred embodiment, the hydroprocessing reactor 20 comprises a diesel hydrotreating reactor. Again, these are merely preferred and it is believed that the principles of the present invention can be utilized in association with any hydroprocessing reactors 20 to derive the same benefits of lower capital cost and less plot space.

The separator vessel 10 is a cold separator usually operating at a temperature of less than about 150° C., such as about 50° C. to 65° C. Additional, the separator vessel 10 preferably has an operating pressure of approximately 30 to 180 Kg/cm². In the separator vessel 10, components of the hydroprocessed effluent 12 will separate into a liquid hydrocarbon stream 22, a vapor stream 24, and a sour water stream 26.

The liquid hydrocarbon stream 22 can be passed to, for example, a stripping zone (not shown) for separation of the liquid products from hydrogen, hydrogen sulfide and light hydrocarbons boiling outside of the desired product range. The vapor stream 24 can be passed to a compressor (not shown) and then routed to join with the feed and is known as a recycle gas. As mentioned above, and as will be discussed in more detail below since the recycle gas scrubber has been combined with the separator vessel 10, there is no need to utilize a knock out drum in passing the vapor stream 24 as a recycle gas to the compressor.

Turning to FIG. 2, the separator vessel 10 includes a substantially cylindrical body 102 with a first end 104, a second end 106, a boot 108 and a tower 110. Generally, the tower 110 is coupled to a top 112 of the substantially cylindrical body 102 and the boot 108 is coupled to the bottom 114 of the substantially cylindrical body 102. The substantially cylindrical body 102 may have a length (distance from the first end 104 to the second end 106) greater than a height (distance from the top 112 of the substantially cylindrical body 102 to the bottom 114 of the substantially cylindrical body 102).

In order to increase the separation between the liquid and the vapor phases of the hydroprocessed effluent 12, a coalescer 116 may extend between the top 112 and the bottom 114 of the substantially cylindrical body 102. Preferably the coalescer 116 comprises a mesh blanket. The coalescer 116 may be disposed between an inlet 118 for the hydroprocessed effluent 12 (typically at the first end 104), and the boot 108 and the tower 110 (typically proximate the second end 106).

The boot 108 has a substantially cylindrical shape and, as mentioned above, is coupled to the bottom side 114 of the substantially cylindrical body 102. The liquid hydrocarbons and the sour water in the hydroprocessed effluent 12 will separate due to the different polarities between the two liquids. Typically, the boot 108 will receive water which can be withdrawn as the sour water stream 26. Usually this is a sour water. As is known, a controller (not shown) can be coupled to the boot 108 for measuring the water level and communicating with a control valve to regulate that level. An outlet 109 for the liquid hydrocarbon stream 22 is typically disposed at the second end 106 of the substantially cylindrical body 102.

The tower 110 can be orientated substantially perpendicular to the substantially cylindrical body 102 and form a substantially cylindrical shape. Generally, the tower 110 has a height greater than a width and has one or more walls 120 surrounding a void 122 or open interior.

The tower 110 preferably contains at least one chimney tray 124. The at least one chimney tray 124 can form a partition between the tower 110 and the substantially cylindrical body 102. As will be appreciated, vapor in the separator vessel 10 can pass through the at least one chimney tray 124 and rise into the tower 110. The at least one chimney tray 124 can include a liquid collection well 128 (discussed in more detail below).

Disposed within the tower 110 and above the at least one chimney tray 124 is a scrubbing zone 130. The scrubbing zone 130 includes a packed sections 132 having structured or random packing or trays.

A lean amine stream 134 is passed into the tower 110 above the packed bed or trays 132 of the scrubbing zone 130. The lean amine absorbs hydrogen sulfide and other acid gases from vapor traveling upwards in the tower 110 of the separator vessel 10. The lean amine will become rich amine and drop onto the chimney tray 124. The rich amine will accumulate in the liquid collection well 128 of the chimney tray 124 and can be recovered from the tower 110 in a rich amine stream 136. As is known, the rich amine stream 136 can be processed further to remove the hydrogen sulfide, whereupon the lean amine is recycled back to the scrubbing section via as the lean amine stream 134.

The treated recycled gas (i.e., the vapor stream 24) can be removed from an outlet 138 at the top of the tower 100, and, as mentioned above, passed for example to a compressor or other equipment for further processing.

In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

It should be appreciated and understood by those of ordinary skill in the art that various other components such as valves, pumps, filters, coolers, etc. were not shown in the drawings as it is believed that the specifics of same are well within the knowledge of those of ordinary skill in the art and a description of same is not necessary for practicing or understating the embodiments of the present invention.

While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.

Claims

1. A separator vessel for separating and treating a portion of an effluent stream, the separator vessel comprising:

a body having a first end, a second end, a top, a bottom, and an inlet for an effluent stream, the inlet disposed near the first end of the body;

a boot extending away from the bottom of the body; and,

a tower extending away from the top of the body, the tower disposed above at least a portion of the boot, wherein the tower includes a scrubbing section configured to remove hydrogen sulfide from gases within the body of the separator vessel.

2. The separator vessel of claim 1 further comprising:

a chimney tray disposed in the tower between the body of the separator vessel and the scrubbing section of the tower.

3. The separator vessel of claim 2 further comprising:

an outlet for rich amine associated with the chimney tray.

4. The separator vessel of claim 1, further comprising:

an inlet for lean amine disposed in the tower above the scrubbing section.

5. The separator vessel of claim 1 further comprising:

a demister extending between the top of the separator vessel and the bottom of the separator vessel and disposed between the first end of the separator vessel and the tower.

6. The separator vessel of claim 1 further comprising:

an outlet for a liquid hydrocarbon stream disposed proximate the second end of the body.

7. The separator vessel of claim 1 wherein the scrubbing section comprises at least one packed bed or tray.

8. The separator vessel of claim 1 further comprising:

an outlet for treated vapor disposed proximate a top of the tower.

9. The separator vessel of claim 1 wherein an operating pressure of the separator vessel is approximately 40 to 180 Kg/cm2.

10. A process for separating and treating a liquid effluent stream from a hydroprocessing zone, the process comprising:

passing a liquid effluent stream from a hydroprocessing zone to a separation zone;

separating the liquid effluent stream into a liquid portion and a vapor portion in the separation zone, wherein the separation zone comprises at least one vessel comprising: a body having a first end, a second end, a top, a bottom, and an inlet for a hydrotreated effluent stream, the inlet disposed near the first end of the body; a boot extending away from the bottom of the body; and, a tower extending away from the top of the body, the tower disposed above at least a portion of the boot, wherein the tower includes a scrubbing section; and,

removing hydrogen sulfide from the vapor portion of the liquid effluent stream within the at least one vessel.

11. The process of claim 10 wherein an operating pressure of the at least one vessel of the separation zone is approximately 40 to 180 Kg/cm2.

12. The process of claim 10 further comprising:

hydrotreating a feed stream in the hydroprocessing zone to produce a hydrotreated stream, wherein the hydrotreated stream comprises the liquid effluent stream from the hydroprocessing zone.

13. The process of claim 12 wherein the hydrotreated stream comprises a hydrotreated diesel stream.

14. The process of claim 10 wherein the at least one vessel further comprises a chimney tray disposed in the tower between the body of the vessel and the scrubbing section of the tower.

15. The process of claim 10 wherein the at least one vessel further comprises a demister extending between the top of the vessel and the bottom of the vessel and disposed between the first end of the vessel and the tower.

16. The process of claim 10 wherein the at least one vessel further comprises an outlet for a liquid hydrocarbon stream disposed proximate the second end of the body.

17. The process of claim 10 wherein the scrubbing section of the at least one vessel further comprises at least one packed bed or trays.

18. The process of claim 10 wherein the at least one vessel further comprises an outlet for treated vapor disposed proximate a top of the tower.

19. The process of claim 10 further comprising:

hydrocracking a feed stream in the hydroprocessing zone to produce a hydrocracked stream, wherein the hydrocracked stream comprises the liquid effluent stream from the hydroprocessing zone.

20. A separator vessel for separating a portion of an effluent stream into a vapor stream and a liquid stream and for treating the vapor stream within the vessel, the separator vessel comprising:

a body having a first end, a second end, a top, a bottom, and an inlet for an effluent stream, the inlet disposed near the first end of the body;

a boot extending away from the bottom of the body;

an outlet for a liquid hydrocarbon stream disposed proximate the second end of the body;

a tower extending away from the top of the body, the tower disposed above at least a portion of the boot, wherein the tower includes at least one packed bed or tray; and,

a second outlet for a scrubbed vapor stream disposed proximate a top of the tower.