Integrated stabilizer in deisobutanizer for isomerization of hydrocarbons and product separation

Abstract

An isomerization method consists of a deisobutanizer column receives feed comprising n-butane. The deisobutanizer column delivers its bottoms a portion to a reboiler and another portion along with hydrogen is routed to a isomerization reactor and the reactor effluent is returned to the column. A stabilizer which is integrated with the column, an overhead stream used as a reflux and bottoms containing an iso-butane-rich stream that is the iso-butane product stream.The column overhead effluent is routed to separator, which splits the hydrocarbons and effluent, where the hydrocarbons are routed to deisobutanizer column and effluent recycled to stabilizer, where the stabilizer separates the reactor effluent into product streams contains an iso-butane product stream, a n-butane product stream, and a lighter hydrocarbon product stream.

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] This applicationThis application is an application for reissue of U.S. Pat. No. 11,306,047, issued on Apr. 19, 2022, entitled “Integrated Stabilizer in Deisobutanizer for Isomerization of Hydrocarbons and Product Separation” and filed on Apr. 13, 2021, as U.S. patent application Ser. No. 17 / 229,527, which claims priority to U.S. Provisional Patent Application having Ser. No. 63 / 011,058 filed on Apr. 16, 2020 which is incorporated by reference herein.TECHNICAL FIELD

[0002] The present invention relates to isomerization of hydrocarbons and fractionation of the product effluent stream for effective separation of iso-paraffins from feedstock and more particularly relates to such isomerization processes that include an integrated stabilizer in fractionation section.BACKGROUND

[0003] About 90% of the total butane consumption in the United States is in gasoline manufacture where n-butane is used directly as a blending component, and isobutane is either used for the production of high octane alkylate or for the production of isobutylene to make methyl tert-butyl ether. Chemical uses account for another 6-8% of the total butanes. Due to the recent increased demand for high octane gasoline and the federally regulated reduction of gasoline vapor pressure, there is the need to have a process that can effectively convert normal butane to isobutane to ultimately increase the production of high octane blending components.

[0004] As the boiling points of normal butane and isobutane are relatively close and a relatively pure isobutane product is desired, the deisobutanizer typically is operated with a high reflux ratio. Thus, the heat duty of the deisobutanizer is a significant component of the operating costs of a butane isomerization process, and the heat duty becomes increasingly significant as higher purity isobutane product streams are sought. Accordingly, improved normal butane isomerization processes are sought that have improved capital and operating cost.

[0005] The objective of the present invention is Methods and apparatuses for the isomerization of hydrocarbons and fractionation having reduced reflux demand and reboiler duty by Stabilizer integrated with deisobutanizer columns.SUMMARY

[0006] An isomerization system consists of a deisobutanizer column receives feed comprising n-butane. The deisobutanizer column delivers its bottoms a portion to a reboiler and another portion along with hydrogen is routed to an isomerization reactor and the reactor effluent is returned to the column. A stabilizer which is integrated with the column, an overhead stream of stabilizer used as a reflux and bottoms containing an iso-butane-rich stream that is iso-butane product stream.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1—Typical scheme of iso-butane unit with stabilizer section; isomerization of n-butane to iso-butane by stabilizer integrated with deisobutanizer column;

[0008] FIG. 2—Stabilizer section in the bottom of the deisobutanizer; isomerization of n-butane to iso-butane by stabilizer integrated at the bottom of the deisobutanizer column;

[0009] FIG. 3—Typical scheme of isomerization unit with stabilizer section; isomerization of hydrocarbons i.e. n-butane, n-pentane, n-hexane, n-heptane, to isomerate and heavy isomerate by stabilizer integrated with Catalytic distillation column;DETAILED DESCRIPTION

[0010] An isomerization system consists of a deisobutanizer column receives feed comprising n-butane. The deisobutanizer column delivers its bottoms a portion to a reboiler and another portion along with hydrogen is routed to an isomerization reactor and the reactor effluent is returned to the column. A stabilizer which is integrated with the column, an overhead stream of stabilizer used as a reflux and bottoms containing an iso-butane-rich stream that is the iso-butane product stream.

[0011] Methods and apparatuses for the isomerization of hydrocarbons and fractionation of the product effluent stream. Stabilizer columns have been traditionally used in isomerization of hydrocarbons. The invention could provide an isomerization process having lower capital costs and lower utilities costs due to the integration of the stabilizer section into the rectification or reaction-rectification column. The reduction of reflux demand of the distillation column due to the heat exchange between stabilizer and distillation sections, the reduction of reboiler duty are the effects of the invention. Exemplary embodiments are provided below.

[0012] More specifically as shown in FIG. 1, n-C4 isomerization; stabilizer section integrated into the top of the deisobutanizer. One exemplary embodiment can be a process for isomerizing a feed stream including n-butane. The feed stream comprising of n-butane is sent to the deisobutanizer column. The deisobutanizer column delivers its bottoms a portion to a reboiler and another portion from its bottom or from a tray located above the bottom along after mixing with hydrogen is routed to a isomerization reactor and the reactor effluent is returned to the column . . . . The overhead stream of the deisobutanizer is partially used as reflux and partially sent to the stabilization section, which is integrated into the top of the deisobutanizer column. C1-C3 hydrocarbons are removed in the section and the bottom product contains at least 93% wt of isobutane. compared to traditional schemes, in which the reactor effluent is sent to the stabilizer column first, present scheme has lowered specific overall reflux demand and reboiler duty.

[0013] Another embodiment of the invention as shown in FIG. 2, n-C4 isomerization; stabilizer section integrated into the bottom of the deisobutanizer. Another exemplary embodiment can be a process for n-butane isomerizing. The stabilizer section is integrated into the bottom part of the deisobutanizer column. The feed stream comprising of n-butane is sent to the deisobutanizer column. The deisobutanizer column delivers its bottoms a portion to a reboiler and another portion from its bottom or from a tray located above the bottom after mixing with hydrogen is routed to a isomerization reactor. The output stream of the reactor is sent to the stabilizer section, where C1-C3 hydrocarbons are removed. The bottom stream of the stabilizer section is partially reboiled and partially sent to the deisobutanizer column. Commercial iC4 product is taken from the overhead stream of the deisobutanizer. heat integration between stabilizer section and bottom part of deisobutanizer column allows to lower the reboiler duty on the deisobutanizer column.

[0014] Another embodiment of the invention as shown in FIG. 3, Isomerization technology with integrated stabilizer section. Another exemplary embodiment is a process for isomerizing a C5-C6 and / or C6-C7 fractions. The process includes providing a hydrocarbon stream to the reaction-rectification column. The top product from the high pressure separator is returned into the column as reflux, another part is sent to the stabilization section integrated into the top of the reaction-rectification column. C1-C3 hydrocarbons are removed in the section, the bottom product which contains mostly branched C5+ hydrocarbons is admixed with isomerate product out of the column. Present invention provides lowered reflux demand due to the heat integration of stabilizer section and distillation part of the column.

[0015] A catalytic distillation column receives feed, wherein some part of the feed goes down through the catalytic distillation column to a reboiler and leaves the column as heavy isomerate. Light fraction of the feed goes upward through the catalytic distillation column. A stabilizer which is integrated with the column, an overhead stream used as a reflux after separating the lighter hydrocarbons through low pressure separator and bottoms of stabilizer containing an isomerate rich product stream, a portion is recycled to stabilizer after reboil through reboiler. the column overhead effluent is routed to high pressure separator, which splits the hydrocarbons and effluent hydrogen, where the hydrocarbons are routed to stabilizer in the column, which is integrated with top of the catalytic distillation column and effluent hydrogen recycled to column through compressor and dryer. The column has a side-draw product that is isomerate. The isomerate-rich stream is taken from a point selected from the side draw of an catalytic distillation column and or a bottom section of the stabilizer. The side draw isomerate-rich stream is vapor, liquid, or a combination thereof.

[0016] The stabilizer comprises an overhead cooler configured to condense vapors from the column and the stabilizer. A reflux stream from the overhead condenser is fed to a top tray of the stabilizer.

[0017] It will be appreciated that the system and process described herein are not limited to any particular temperature ranges, pressure ranges, flow rates, stream compositions, and the like. It is expected that the system and process, now that it is described, can be modified by one of ordinary skill in the art to be applicable to a variety of reactor effluent compositions and other conditions and parameters as necessary.

[0018] It will also be appreciated that the systems and processes described herein will have a number of technical and commercial advantages. Technical advantages include, but are not necessarily limited to:

[0019] Improvement of fractionation efficiency;

[0020] Reduced utility requirements;

[0021] Reduced overall energy requirements;

[0022] Reduced reflux demand;

[0023] Reduced reboiler duty; and

[0024] Reduced iso-butane loss from the system.

[0025] Commercial advantages include, but are not necessarily limited to:

[0026] 20-30% less capital requirement as compared to the conventional column solutions;

[0027] Improvement in fractionation economics;

[0028] Less plot space (equipment footprint) requirement;

[0029] Advantages for plant upgrading / debottlenecking;

[0030] Overall improvement in the value of products; and

[0031] Alternative use of existing assets to improve overall economics of the plant.

[0032] In the foregoing specification, the invention has been described with reference to specific embodiments thereof. However, the specification is to be regarded in an illustrative rather than a restrictive sense. For example, equipment, columns, stabilizer, processes, reactants, n-paraffins, isoparaffins, products, isomerate, and operating conditions falling within the claimed or disclosed parameters, but not specifically identified or tried in a particular example, are expected to be within the scope of this invention.

[0033] The present invention may be practiced in the absence of an element not disclosed. In addition, the present invention may suitably comprise, consist or consist essentially of the elements disclosed. An isomerization system consists of a deisobutanizer column or catalytic distillation column receives feed comprising n-butane. The deisobutanizer column delivers its bottoms a portion to a reboiler and another portion along with hydrogen is routed to an isomerization reactor and the reactor effluent is returned to the column. A stabilizer which is integrated with the column, an overhead stream of stabilizer used as a reflux, lighter hydrocarbons i.e. C1-C3 hydrocarbons and bottoms containing an iso-butane-rich stream that is the iso-butane product stream.

[0034] The words “comprising” and “comprises” as used throughout the claims, are to be interpreted to mean “including but not limited to” and “includes but not limited to”, respectively.

[0035] As used herein, the word “substantially” shall mean “being largely but not wholly that which is specified.”

[0036] As used herein, the singular forms “a,”“an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0037] As used herein, the term “about” in reference to a given parameter is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the given parameter).

[0038] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

Claims

1. An isomerization n-paraffins and fractionation system comprising:a deisobutanizer column receivescomprising a feed comprising n-paraffins, containing feedstock, it deliversa bottoms stream, and a deisobutanizer column overhead stream; a portion to a reboiler arranged to receive at least a first portion of the bottoms stream from the deisobutanizer column;an isomerization reactor receives anotherarranged to receive a second portion of the bottoms stream from the deisobutanizer column bottom or an effluent from a tray located above an output of the bottom after mixingbottoms stream in the deisobutanizer column, and configured to mix the second portion of the bottoms stream or the effluent from the tray located above the output of the bottoms stream with hydrogen andto yield a reactor effluent, wherein the reactor effluent is returneddirected to the deisobutanizer column;a stabilizer which is integrated with the deisobutanizer column, anthe stabilizer comprising a stabilizer overhead stream usedprovided as a reflux to the stabilizer and a stabilizer bottoms containing an isomerate rich stream that is an isomerate product stream; and a separator which receives arranged to receive the deisobutanizer column overhead stream, which splits the the separator configured to split hydrocarbons in the deisobutanizer column overheard stream into at least two overhead streams, wherein the first at least one overhead stream is routed to the deisobutanizer column as its reflux, and the rest any remaining overhead streams are routed to the stabilizer;where the stabilizer separates the reactor effluent into product streams comprising:an isomerate product stream, anda lighter hydrocarbon product stream.

2. The isomerization n-paraffinssystem of claim 1, where at least a portion of the isomerate product stream is recycled to the stabilizer in a recycle stream.

3. The isomerization n-paraffinssystem of claim 1, where the stabilizer separatesis configured to separate the isomerate effluent into branched C4+ hydrocarbons, and a lighter hydrocarbon product stream along with hydrogen.

4. The isomerization n-paraffinssystem of claim 1, further comprising an intermediate reboiler in a bottom section of the reboilerstabilizer, and wherewherein the isomerate product stream is a heating medium in the intermediate reboiler.

5. A method for isomerization of n-butane comprises comprising:feeding an n-butane-rich fraction is a feed to thea deisobutanizer column containing an integrated stabilizer;a reactor effluent is a feed to a deisobutanizer column containing stabilizer;delivering a first portion of a bottoms stream of the deisobutanizer column delivers its bottoms a portion to a reboiler; and anothermixing a second portion after mixing with hydrogen is routedof the bottoms stream of the deisobutanizer column with hydrogen to form a mixture and delivering the mixture to an isomerization reactor; to anrouting a reaction effluent from the isomerization reactor and the reactor effluent is returned to the integrated stabilizer;in the deisobutanizer column, the stabilizer integrated with column of the deisobutanizer column;wherein, the stabilizer has an overhead light hydrocarbons that iscomprising C1-C3 hydrocarbons and hydrogen; andwithdrawing from the deisobutanizer column has an overhead product withdrawn from the column and / or stabilizer that is isomerate stream that is theproduct comprising an iso-butane product stream.

6. The method of claim 5, wherefurther comprising recycling a portion of the overhead iso-butane-richiso-butane product stream is a recycle stream to the deisobutanizer column.

7. The method of claim 5, further comprising feeding a bottoms stream from the integrated stabilizer to an intermediate reboiler inprovided at a bottom section of the deisobutanizer column.

8. An isomerization and fractionation method for n-paraffin's comprising:a catalytic distillation column receives feedfeeding a feed comprising n-paraffins,to a catalytic distillation column, wherein the catalytic distillation column comprises an integrated stabilizer; which catalytic distillation column delivers its bottoms a portiondelivering a first portion of a bottoms stream of the catalytic distillation column to a reboiler, and anotherwherein a second portion isof the bottoms stream of the catalytic distillation column comprises a heavy isomerate;a stabilizer which is integrated with the column, separating lighter hydrocarbons from an overhead stream used as a reflux after separating the lighter hydrocarbons through of the integrated stabilizer via a low pressure separator and to yield a remaining overhead stream of the integrated stabilizer, and using the remaining overhead stream of the integrated stabilizer as reflux to the integrated stabilizer;reboiling using a reboiler and then recycling a portion of the bottoms stream of the integrated stabilizer, containingwherein the bottoms stream of the integrated stabilizer comprises an isomerate rich product stream, a portion is recycled to stabilizer after reboiling through reboiler;the columnrouting an overhead effluent is routedof the catalytic distillation column to a high pressure separator, which splits theto separate hydrocarbons and effluent hydrogen, whereand directing the hydrocarbons are routed to the integrated stabilizer in a top portion of the column, which is integrated with top of the deisobutanizer columncatalytic distillation column; and the column has a side-draw product that is withdrawing an isomerate; product stream from the catalytic distillation column where the stabilizer separates the reactor effluent into product streams comprising:an isomerate product stream, anda light hydrocarbon stream.

9. The isomerization method of claim 8, where the feed iscomprises C5-C6, C6-C7, or C5-C7 fractions.

10. The isomerization method of claim 8, where the lighter hydrocarbon product stream containinghydrocarbons comprise C1-C3 hydrocarbons.

11. The isomerization method of claim 8, where the isomerate product stream iscomprises branched C4+ hydrocarbons.

12. The isomerization method of claim 8, further comprising employing the isomerate product stream as a heating medium in an intermediate reboiler inat a bottom section of the reboiler, and where the isomerate product stream is a heating medium in the intermediate reboilerintegrated stabilizer.

13. The isomerization method of claim 8 where the stabilizer at or near the top or near the bottom of the column.

14. The isomerization method of claim 8, where the isomerate-richisometric product stream is takenwithdrawn from a point selected from thea side draw of the catalytic distillation column and or a bottom section of the stabilizer.

15. The isomerization method of claim 814, where the side draw that is isomerate-richisomarate product stream is selected from the group consisting ofcomprises vapor, liquid, or a combination thereof.

16. The isomerization method of claim 8, where the isomerate-richisomarate product stream is acomprises branched C4+ hydrocarbons.

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