Method and apparatus for separating aromatic and non-aromatic hydrocarbons

Abstract

A process and apparatus for separating aromatic and non-aromatic hydrocarbons by extractive distillation. A solvent is mixed with the aromatic hydrocarbon and the non-aromatic hydrocarbon. A first separation column separates non-aromatic hydrocarbons from the solvent and the aromatic hydrocarbons. A second separation column separates the aromatic hydrocarbon from the solvent. A side draw stream from the second separation column is used to heat a feed stream to the first separation column. A bottoms stream from the second separation may be used to heat liquid in the first separation column. A plug-in reboiler may be used to transfer heat from the bottoms stream to the liquid in the first separation column.

Description

[0001] Priority declaration

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 377,807, filed on September 30, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention generally relates to methods and apparatus for separating aromatic hydrocarbons from non-aromatic hydrocarbons, and more particularly to methods and apparatus for transferring heat to effectively and efficiently separate aromatic hydrocarbons from non-aromatic hydrocarbons. Background Art

[0004] Extractive distillation is a separation process used in chemical processing, particularly for recovering aromatic hydrocarbons from a mixed stream of aromatic and non-aromatic hydrocarbons. The key aspect of extractive distillation is the addition of a separating agent (solvent with a high boiling point) to the mixture of components for separation, increasing relative volatility when the components of the mixed stream have similar or close boiling points. Typically, two columns are utilized in extractive distillation - an extractive distillation column and a solvent recovery column.

[0005] The extractive distillation column separates the aromatic components from the non-aromatic components, while the solvent recovery column separates the aromatic components from the solvent. The final extracted aromatic stream is discharged from the top of the solvent recovery column.

[0006] While extractive distillation is effective for its intended purpose, there remains a continuing need to reduce utility demands and provide more efficient separation methods. Summary of the invention

[0007] The present invention provides extractive distillation with reduced utility losses compared to existing solutions.

[0008] According to the present invention, a side draw from the recovery column is utilized to return solvent to the extractive distillation column, which reduces the duty requirement at the recovery column reboiler. In existing solutions, the extractive distillation column uses a reboiler with an external process-process heat exchanger followed by a utility heat exchanger. The extractive distillation column reboiler preheater duty is limited by the boil-off percentage to the utility reboiler due to concerns about maldistribution. In the side draw flow scheme, the reboiler preheater mean temperature difference (MTD) is reduced due to the lower hot side solvent flow rate. Internal heat exchangers, such as inserted reboiler preheaters, further reduce utility losses and can also reduce concerns about boil-off and improve exchanger MTD.

[0009] Therefore, in at least one aspect, the general feature of the present invention is to provide a method for separating aromatic hydrocarbons and non-aromatic hydrocarbons by: in a first separation zone, separating a feed stream containing aromatic hydrocarbons and non-aromatic hydrocarbons into a first stream containing non-aromatic hydrocarbons and a second stream containing aromatic hydrocarbons and a solvent; in a second separation zone, separating the second stream into a third stream containing aromatic hydrocarbons, a fourth stream containing solvent and a fifth stream containing solvent, wherein the fourth stream contains a side-draw stream; in a first heat transfer zone, transferring heat from the fifth stream to the first separation zone; and in a second heat transfer zone, transferring heat from the fourth stream to the feed stream, wherein the fourth stream is transferred from the second heat transfer zone to the first separation zone, and wherein the fifth stream is transferred to the first separation zone after transferring the heat to the first separation zone.

[0010] The present invention may also be broadly characterized in at least one aspect as providing a method for separating aromatic hydrocarbons and non-aromatic hydrocarbons by: conveying a feed stream comprising aromatic hydrocarbons and non-aromatic hydrocarbons to a first separation zone comprising a separation tower, the separation tower being configured to provide a first stream comprising non-aromatic hydrocarbons and a second stream comprising aromatic hydrocarbons and a solvent; conveying the second stream to a second separation zone comprising a separation tower, the separation tower being configured to provide a third stream comprising aromatic hydrocarbons, a fourth stream comprising solvent, and a fifth stream comprising solvent, wherein the fourth stream comprises a side-draw stream; conveying the fifth stream to a first heat transfer zone, the first heat transfer zone being configured to transfer heat from the fifth stream to the first separation zone, wherein the first heat transfer zone is inside the separation tower in the first separation zone; conveying the fourth stream to a second heat transfer zone, the second heat transfer zone being configured to transfer heat from the fourth stream to the feed stream; and after conveying the fourth stream to the second heat transfer zone, conveying the fourth stream to the separation tower in the first separation zone.

[0011] In one or more aspects, the invention is also generally characterized by providing an apparatus for separating aromatic hydrocarbons from non-aromatic hydrocarbons, the apparatus having: a first separation zone, which includes a separation column, the separation column configured to receive a feed stream comprising aromatic hydrocarbons and non-aromatic hydrocarbons and provide a first stream comprising non-aromatic hydrocarbons and a second stream comprising aromatic hydrocarbons and a solvent; a second separation zone, which includes a separation column, the separation column configured to receive the second stream and provide a third stream comprising aromatic hydrocarbons, a fourth stream comprising solvent, and a fifth stream comprising solvent, wherein the fourth separation zone comprises ..., the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, the separation column, The material stream includes a side-draw material stream; a first heat transfer zone, which is configured to transfer heat from a fifth material stream to a first separation zone, wherein the first heat transfer zone is disposed in a separation tower in the first separation zone; a second heat transfer zone, which is configured to transfer heat from a fourth material stream to a feed material stream; a third heat transfer zone, which is configured to transfer heat from a fifth material stream to the feed material stream; a pipeline configured to transfer the fifth material stream from the third heat transfer zone to the separation tower in the first separation zone; and a pipeline configured to transfer the fourth material stream from the second heat transfer zone to the separation tower in the first separation zone.

[0012] Further aspects, embodiments and details of the invention (all of which may be combined in any manner) are set forth in the following detailed description of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] One or more exemplary embodiments of the present invention will be described below in conjunction with the following drawings, in which:

[0014] Figure 1 A process flow chart of one aspect of the present invention;

[0015] Figure 2 A process flow chart of another aspect of the present invention;

[0016] Figure 3 A side partial cross-sectional view showing a portion of an extractive distillation column according to one or more aspects of the present invention; and,

[0017] Figure 4 Shown along Figure 3 A top sectional view taken along pipeline A1-A2 in FIG. DETAILED DESCRIPTION

[0018] As used herein, the term "stream" may include various hydrocarbon molecules and other species.

[0019] As used herein, the terms "stream", "feed", "product", "portion" or "fraction" may include various hydrocarbon molecules such as straight and branched alkanes, cycloalkanes, olefins, alkadienes and alkynes, and optionally other species such as gases, for example hydrogen, or impurities such as heavy metals, and sulfur and nitrogen compounds. Each of the above may also include aromatic hydrocarbons and non-aromatic hydrocarbons.

[0020] As used herein, the term "overhead stream" may mean a stream withdrawn at or near the top of a vessel, such as a column.

[0021] As used herein, the term "bottoms stream" may mean a stream withdrawn at or near the bottom of a vessel, such as a column.

[0022] Hydrocarbon molecules may be abbreviated as C1, C2, C3, Cn, where "n" represents the number of carbon atoms in one or more hydrocarbon molecules, or the abbreviation may be used as an adjective, such as a non-aromatic hydrocarbon or compound. Similarly, aromatic compounds may be abbreviated as A6, A7, A8, An, where "n" represents the number of carbon atoms in one or more aromatic molecules. In addition, superscripts "+" or "-" may be used with the abbreviated hydrocarbon symbol or symbols, such as C3+ or C3-, including the abbreviated hydrocarbon or hydrocarbons. As an example, the abbreviation "C3+" means one or more hydrocarbon molecules having three or more carbon atoms.

[0023] As used herein, the term "zone" may refer to an area that includes one or more equipment items and / or one or more sub-zones. Equipment items may include, but are not limited to, one or more reactors or reactor vessels, separation vessels, distillation columns, heaters, exchangers, pipelines, pumps, compressors, and controllers. In addition, equipment items such as reactors, dryers, or vessels may also include one or more zones or sub-zones.

[0024] The term "tower" means one or more distillation columns for separating one or more components with different volatilities. Unless otherwise specified, each tower includes a condenser at the top of the tower for condensing a portion of the overhead stream and refluxing it back to the top of the tower, and a reboiler at the bottom of the tower for vaporizing a portion of the bottom stream and sending it back to the bottom of the tower. The feed to the tower can be preheated. The top or top pressure is the pressure of the overhead vapor at the vapor outlet of the tower. The bottom temperature is the liquid bottom outlet temperature. Unless otherwise specified, the net top line and the net bottom line refer to the net line from any reflux or reboiled tower downstream to the tower. The stripping tower can omit the reboiler at the bottom of the tower, and instead provide the heating requirements of the fluidized inert medium (such as steam) and the power to separate it.

[0025] As depicted, the process flow lines in the figures may be referred to interchangeably as, for example, lines, pipes, feeds, gases, products, effluents, portions, parts, or streams.

[0026] The term "delivery" means the transfer of a substance from a conduit or container to an object.

[0027] As described above, the present invention is directed to extractive distillation including a solvent side draw from a recovery column with a solvent side draw feed heater and an inserted extractive distillation column reboiler preheater. The addition of a solvent side draw from the recovery column allows for heat savings since the entire solvent stream no longer has to be heated to the column bottom temperature. Studies have shown that recycling 30%-40% of the total solvent stream via the side draw yields a 5% energy benefit over conventional designs.

[0028] The addition of a solvent side draw feed exchanger is one aspect of the present invention. The exchanger cools the solvent side draw while heating the hydrocarbon feed entering the unit. Including the exchanger redistributes heat within the extractive distillation column and based on the location of the heat flow, the overall solvent to feed ratio can be reduced by 13% over existing designs such as those described in US5,180,474. In addition to the energy benefits, these differences allow for smaller equipment through lower solvent to feed ratios, which is a surprising and unexpected result.

[0029] Further energy benefits can be achieved by implementing an inserted extractive distillation reboiler preheater in conjunction with a solvent side draw. With a solvent side draw included, there is less solvent mass flow from the recovery column bottoms. The recovery column bottoms material is used to heat the extractive distillation column reboiler preheater, and for lower bottoms flows, there is less heat in the stream to deliver to the extractive distillation column. To alleviate concerns about low MTD, an inserted reboiler preheater can be utilized. The inserted preheater operates at the column bottoms pressure, which means that the outlet temperature is lower than the outlet temperature of an external reboiler operating at a higher pressure. Separating the extractive distillation column reboiler preheater from the extractive distillation column pumped reboiler loop also eliminates concerns about uneven distribution in the main reboiler due to vapor at the tube side inlet. Implementing a vertical reboiler allows the removal of large reboiler pumps from existing process flow schemes, which can reduce costs and allow an additional 5%-6% energy benefit relative to a separate side draw stream scheme.

[0030] With an inserted reboiler, the cooler liquid from the tray section contacts the reboiler preheater since the highest hot side temperature is set by the recovery column bottom. The vaporized material from the reboiler preheater is able to rise up the column while the liquid continues to the external reboiler. This configuration effectively creates a two-stage reboiler since the vapor from each reboiler is actually a different temperature. The reboiler preheater and main reboiler operate in series as opposed to the more common parallel configuration.

[0031] With these general principles in mind, one or more embodiments of the invention will be described with the understanding that the following description is not intended to be limiting.

[0032] like Figure 1 and Figure 2 As shown, a hydrocarbon feed stream 10 containing a mixture of aromatic and non-aromatic hydrocarbons is fed to a first separation zone 12. The first separation zone comprises an extractive distillation column 14. A first solvent stream 16 is also passed to the extractive distillation column 14, preferably at a location above the hydrocarbon feed stream 10.

[0033] As is known, in the extractive distillation column 14, a solvent mixes with the hydrocarbons in the feed and affects the volatility of the hydrocarbon feed to facilitate separation of the various hydrocarbon-containing fluid components by distillation and such solvent exits with the bottoms fraction. An example solvent is tetrahydrothiophene 1,1-dioxide (or sulfolane).

[0034] Thus, a non-aromatic compound vapor stream 18 exits the top of the extractive distillation column 14, is condensed via a condenser 20, and is passed to an overhead receiver 22. In the overhead receiver 22, phase separation between the non-aromatic hydrocarbons and the aqueous phase occurs. Thus, a non-aromatic hydrocarbon stream 24 and a water stream 26 are recovered from the overhead receiver 22. A first portion 24a of the non-aromatic hydrocarbon stream 24 may be recycled to the extractive distillation column 14 as a reflux. The liquid stream 26 may also be returned to the extractive distillation column 14. A second portion 24b of the non-aromatic hydrocarbon stream 24 is a non-aromatic hydrocarbon stream, and further processing of the second portion 24b of the non-aromatic hydrocarbon stream 24 is not described because it is known in the art.

[0035] The bottoms stream 28 from the extractive distillation column 14 comprises solvent and aromatic hydrocarbons and is passed to a second separation zone 40. In addition, a liquid stream 30 comprising a mixture of solvent and aromatic hydrocarbons is withdrawn from the extractive distillation column 14 and heated in a heat transfer zone 32 having a heat exchanger 34 (discussed in more detail below). In another heat transfer zone 36, a heat exchanger 38, such as a vapor reboiler, may also provide additional heat to the liquid stream 30, which is then recycled to the extractive distillation column 14 to generate vapor in the extractive distillation column 14.

[0036] The second separation zone 40 includes a solvent recovery tower 42. As is well known, in the solvent recovery tower 42, the solvent and the aromatic hydrocarbons are separated according to the boiling point. Therefore, the aromatic tower top stream 44 leaves the top of the solvent recovery tower 42, is condensed via a condenser 46, and is cooled in a cooler 48, and is transferred to a tower top receiver 50. In the tower top receiver 50, a phase separation between the hydrocarbon and the water phase occurs. Therefore, an aromatic hydrocarbon stream 52 and a water stream 54 are recovered from the tower top receiver 50. The tower top receiver 50 also includes a pipeline 56 for steam. The first part 52a of the aromatic hydrocarbon stream 52 can be recycled to the solvent recovery tower 42 as a reflux. The water stream 54 can be sent to a solvent regeneration zone 57, which is not described in detail because it is known in the art.

[0037] The bottoms stream 58 from the solvent recovery column 42 comprises primarily solvent which can be reused in the first separation zone 12 to separate the aromatic and nonaromatic hydrocarbons of the feed stream 10. A first portion 58a of the bottoms stream 58 from the solvent recovery column 42 can be passed to the solvent regeneration zone 57.

[0038] The second portion 58b of the bottoms stream 58 from the solvent recovery column 42 is used to provide heat to the first separation zone 12. Therefore, the second portion 58b of the bottoms stream 58 from the solvent recovery column 42 is passed to the heat transfer zone 32 to heat the liquid stream 30 from the extractive distillation column 14. This transfers heat from the bottoms stream 58 from the solvent recovery column 42 to the first separation zone 12.

[0039] Additionally, a second portion 58b of the bottoms stream 58 from the solvent recovery column 42 may be used to heat the water stream 54 from the overhead receiver 50 in another heat transfer zone 60. Finally, a second portion 58b of the bottoms stream 58 from the solvent recovery column 42 may be used to heat the feed stream 10 in another heat transfer zone 64 before being passed to the extractive distillation column 14 as the solvent stream 16. As will be appreciated, these heat transfer zones 60, 64 may include heat exchangers 62, 66 to transfer heat between the streams.

[0040] As described above, in various aspects of the present invention, a side draw stream 70 comprising primarily solvent is also provided by the solvent recovery column 42. The side draw stream 70 is passed to a heat transfer zone 72 to provide heat to the feed stream 10 from the side draw stream 70. The heat transfer zone 72 also includes a heat exchanger 74 to transfer heat between the streams. From the heat transfer zone 72, the side draw stream 70 is passed to the extractive distillation column 14, preferably between the solvent stream 16 and the feed stream 10.

[0041] The side draw stream 70 provides some utility savings, and the inclusion of a heat transfer zone 72 to transfer heat from the side draw stream 70 to the feed 10 allows for less total solvent than a flowsheet scheme including a side draw without such a heat transfer zone. The present invention also contemplates additional advantages and benefits when an intervening heat exchanger or reboiler is used.

[0042] Therefore, if Figure 2 As shown, the heat transfer zone 32 that transfers heat from the second portion 58b of the bottom stream 58 of the solvent recovery column 42 to the extractive distillation column 14 can be an internal heat exchanger located within the extractive distillation column 14. Therefore, the heat exchanger 34 in the heat transfer zone 32 can be an inserted heat exchanger. The heat exchanger 34 is used as a preheater for the bottom reboiler of the extractive distillation column 14.

[0043] Go to Figure 3 and Figure 4 , a preferred configuration of the extractive distillation column 14 having an inserted heat exchanger 34 will be described.

[0044] The extractive distillation column 14 includes a tray section 100 that includes trays and other structures configured to increase contact between vapor rising in the extractive distillation column 14 and liquid descending in the extractive distillation column 14. One or more downcomers 102 are located at the bottom of the tray section 100. As will be understood, the tray section 100 depicted is a 2-channel tray. This is merely exemplary. Other configurations may be utilized, including single-channel trays, or 3-channel trays or 4-channel trays.

[0045] Liquid from the downcomer 102 overflows the weir 104 and is collected on a liquid collector section 106 having a well 108. The liquid from the well 108 will be heated by the intervening exchanger 34, causing a portion of it to reboil and evaporate. The evaporated portion may rise upward in the extractive distillation column 14 toward the tray section 100, through a first riser 110 extending above the liquid collector section 106. The heated liquid from the well 108 overflows the second weir 112 and is collected in a second well 114.

[0046] Liquid stream 76 is withdrawn from second trap 114 and passed to heat exchange zone 36 (see Figure 2 ). The heated stream is returned to the extractive distillation column 14 at injection point 116. The heated liquid is collected from the bottom of the extractive distillation column 14, and a bottoms stream 28 from the extractive distillation column 14 can be withdrawn therefrom.

[0047] The vapor from the bottom material of the extractive distillation column 14 (having a higher temperature than the vapor from the well 108) rises the extractive distillation column 14 toward the tray section 100 through the second riser 118. The second riser 118 also extends above the liquid collector section 106 and bypasses the intervening heat exchanger 34. Therefore, the extractive distillation column 14 has a combined space 120 that receives vapor via the first riser 110 and vapor via the second riser 118. This creates a two-stage reboiler in which the vapor from the preheater (well 108) returns to the tray section 100 of the extractive distillation column 14 through the first riser 110 at a lower temperature than the vapor rising from the primary reboiler and returning to the tray section 100 of the extractive distillation column 14 through the second riser 118.

[0048] This use of the intervening heat exchanger 34 further improves energy efficiency by allowing more heat to be recovered from the bottoms stream 58b from the solvent recovery column 42 and further reduces the utility of the extractive distillation process.

[0049] experiment

[0050] Extractive distillation is typically fed by a larger aromatic complex stream with a stream having 50%-55% aromatic components. Process simulations have estimated that extractive distillation receiving a 53% aromatic feed stream can reduce total utility losses by 5.5%-7.3%, depending on the overall flow scheme utilized.

[0051] Similarly, for an aromatic-rich feed of 73% aromatics, process simulation estimates that the utility loss of extractive distillation can be reduced by up to 9.2%.

[0052] Those of ordinary skill in the art will recognize and appreciate that various other components such as valves, pumps, filters, coolers, etc. are not shown in the accompanying drawings because it is believed that their details are well within the knowledge of those of ordinary skill in the art and their description is not necessary for the practice or understanding of the embodiments of the present invention.

[0053] Any of the above-mentioned pipelines, conduits, units, equipment, containers, surrounding environments, zones, or the like may be equipped with one or more monitoring components, including sensors, measuring devices, data capture devices, or data transmission devices. Signals, process or state measurements and data from the monitoring components can be used to monitor conditions in, around, and related to the process equipment. The signals, measurements, and / or data generated or recorded by the monitoring components can be collected, processed, and / or transmitted via one or more networks or connections, which can be private or public, general or dedicated, direct or indirect, wired or wireless, encrypted or unencrypted, and / or combinations thereof; the present specification is not intended to be limiting in this regard.

[0054] The signals, measurements, and / or data generated or recorded by the monitoring components may be transmitted to one or more computing devices or systems. The computing device or system may include at least one processor and a memory storing computer-readable instructions that, when executed by at least one processor, cause one or more computing devices to perform a method that may include one or more steps. For example, one or more computing devices may be configured to receive data related to at least one piece of equipment associated with the method from one or more monitoring components. One or more computing devices or systems may be configured to analyze the data. Based on the data analysis, one or more computing devices or systems may be configured to determine one or more recommended adjustments to one or more parameters of one or more methods described herein. One or more computing devices or systems may be configured to transmit encrypted or unencrypted data, which includes one or more recommended adjustments to one or more parameters of one or more methods described herein.

[0055] Specific implementation plan

[0056] While the following is described in conjunction with specific embodiments, it should be understood that this description is intended to illustrate and not to limit the scope of the foregoing description and the appended claims.

[0057] The first embodiment of the present invention is a method for separating aromatic hydrocarbons and non-aromatic hydrocarbons, the method comprising separating a feed stream containing aromatic hydrocarbons and non-aromatic hydrocarbons into a first stream containing non-aromatic hydrocarbons and a second stream containing aromatic hydrocarbons and a solvent in a first separation zone; separating the second stream into a third stream containing aromatic hydrocarbons, a fourth stream containing solvent, and a fifth stream containing solvent in a second separation zone, wherein the fourth stream comprises a side-draw stream; transferring heat from the fifth stream to the first separation zone in a first heat transfer zone; and transferring heat from the fourth stream to the feed stream in a second heat transfer zone, wherein the fourth stream is transferred from the second heat transfer zone to the first separation zone, and wherein the fifth stream is transferred to the first separation zone after transferring heat to the first separation zone. An embodiment of the present invention is one, any one, or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, which also includes transferring heat from the fifth stream to the feed stream in the third heat transfer zone. An embodiment of the present invention is one, any one, or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, wherein the first separation zone comprises a separation tower. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, wherein the first heat transfer zone is inside the separation tower. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, wherein in the first heat transfer zone, transferring heat from the fifth stream to the first separation zone includes transferring heat to the liquid in the tower. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, wherein the first heat transfer zone includes an inserted heat exchanger. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, wherein the separation tower includes a liquid collector portion having a first riser and a second riser, the first riser and the second riser both extending above the liquid collector portion, wherein the first riser bypasses the inserted heat exchanger. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, wherein the first riser and the second riser both transfer vapor to the combined space above the liquid collector portion.

[0058] A second embodiment of the present invention is a method for separating aromatic hydrocarbons and non-aromatic hydrocarbons, which includes conveying a feed stream containing aromatic hydrocarbons and non-aromatic hydrocarbons to a first separation zone including a separation tower, the separation tower being configured to provide a first stream containing non-aromatic hydrocarbons and a second stream containing aromatic hydrocarbons and a solvent; conveying the second stream to a second separation zone including a separation tower, the separation tower being configured to provide a third stream containing aromatic hydrocarbons, a fourth stream containing solvent, and a fifth stream containing solvent, wherein the fourth stream contains a side-draw stream; conveying the fifth stream to a first heat transfer zone, the first heat transfer zone being configured to transfer heat from the fifth stream to the first separation zone, wherein the first heat transfer zone is inside the separation tower in the first separation zone; conveying the fourth stream to a second heat transfer zone, the second heat transfer zone being configured to transfer heat from the fourth stream to the feed stream; and after conveying the fourth stream to the second heat transfer zone, conveying the fourth stream to the separation tower in the first separation zone. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the first heat transfer zone includes an inserted heat exchanger. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the separation tower includes a liquid collector portion having a first riser and a second riser, both of which extend above the liquid collector portion, wherein the first riser bypasses the inserted heat exchanger. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein both the first riser and the second riser transfer vapor to the combined space above the liquid collector portion. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, further comprising transferring the fifth stream to a third heat transfer zone before transferring the fifth stream to the first separation zone and after transferring the fifth stream to the first heat transfer zone, the third heat transfer zone being configured to transfer heat from the fifth stream to the feed stream. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the feed stream passes through a third heat transfer zone before being conveyed to the second heat transfer zone. An embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, further comprising conveying the fifth stream to a fourth heat transfer zone before conveying the fifth stream to the third heat transfer zone and after conveying the fifth stream to the first heat transfer zone, the fourth heat transfer zone being configured to transfer heat from the fifth stream.An embodiment of the present invention is one, any one or all of the embodiments from the previous embodiment of this paragraph to the second embodiment of this paragraph, and also includes transferring a liquid stream from a separation tower in a first separation zone to a fifth heat transfer zone, the fifth heat transfer zone being configured to heat the liquid stream and provide a reheated liquid stream, and transferring the reheated liquid stream to a separation tower in a first separation zone below the first heat transfer zone, wherein the liquid stream comprises a solvent and aromatic hydrocarbons.

[0059] A third embodiment of the present invention is an apparatus for separating aromatic hydrocarbons from non-aromatic hydrocarbons, the apparatus comprising a first separation zone, comprising a separation column, the separation column being configured to receive a feed stream comprising aromatic hydrocarbons and non-aromatic hydrocarbons and to provide a first stream comprising non-aromatic hydrocarbons and a second stream comprising aromatic hydrocarbons and a solvent; a second separation zone, comprising a separation column, the separation column being configured to receive the second stream and to provide a third stream comprising aromatic hydrocarbons, a fourth stream comprising solvent, and a fifth stream comprising solvent, wherein the fourth stream comprises a side draw A material stream; a first heat transfer zone configured to transfer heat from the fifth material stream to the first separation zone, wherein the first heat transfer zone is disposed in a separation tower in the first separation zone; a second heat transfer zone configured to transfer heat from the fourth material stream to the feed material stream; a third heat transfer zone configured to transfer heat from the fifth material stream to the feed material stream; a pipeline configured to transfer the fifth material stream from the third heat transfer zone to the separation tower in the first separation zone; and, a pipeline configured to transfer the fourth material stream from the second heat transfer zone to the separation tower in the first separation zone. An embodiment of the present invention is one, any one, or all of the previous embodiments of this paragraph to the third embodiment of this paragraph, wherein the first heat transfer zone includes an inserted heat exchanger. An embodiment of the present invention is one, any one, or all of the previous embodiments of this paragraph to the third embodiment of this paragraph, wherein the separation tower in the first separation zone includes a liquid collector portion having a first riser and a second riser, both of which extend above the liquid collector portion, wherein the first riser bypasses the inserted heat exchanger. An embodiment of the invention is one, any or all of the prior embodiments in this paragraph through the third embodiment in this paragraph wherein both the first riser and the second riser deliver vapor to the combined space above the liquid collector portion.

[0060] Although there is no further detailed description, it is believed that those skilled in the art can utilize the present invention to the greatest extent by using the foregoing description and can easily determine the essential characteristics of the present invention without departing from the spirit and scope of the present invention to make various changes and modifications of the present invention and adapt it to various usages and conditions. Therefore, the aforementioned preferred specific embodiments should be understood as merely illustrative and not to limit the rest of the present disclosure in any way, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0061] In the foregoing, all temperatures are set forth in degrees Celsius and all parts and percentages are by weight unless otherwise indicated.

[0062] Although at least one exemplary embodiment has been presented in the foregoing specific embodiments of the present invention, it should be understood that there are a large number of variations. It should also be understood that an exemplary embodiment or multiple exemplary embodiments are only examples and are not intended to limit the scope, applicability or configuration of the present invention in any way. On the contrary, the foregoing specific embodiments will provide a convenient roadmap for those skilled in the art to implement the exemplary embodiments of the present invention, and it should be understood that various changes can be made to the functions and arrangements of the elements described in the exemplary embodiments without departing from the scope of the present invention as set forth in the attached claims and their legal equivalents.

Claims

1. A method for separating aromatic hydrocarbons from non-aromatic hydrocarbons, the method comprising: Separating a feed stream (10) comprising aromatic hydrocarbons and non-aromatic hydrocarbons into a first stream (18) comprising the non-aromatic hydrocarbons and a second stream (28) comprising the aromatic hydrocarbons and a solvent in a first separation zone (12); separating the second stream (28) in a second separation zone (40) into a third stream (44) comprising the aromatic hydrocarbons, a fourth stream (70) comprising the solvent, and a fifth stream (58) comprising the solvent, wherein the fourth stream (70) comprises a side draw stream; transferring heat from the fifth stream (58) to the first separation zone (12) in a first heat transfer zone (32); and, transferring heat from the fourth stream (70) to the feed stream (10) in a second heat transfer zone (72), wherein the fourth stream (70) is passed from the second heat transfer zone (72) to the first separation zone (12), and wherein the fifth stream (58) is passed to the first separation zone (12) after transferring heat to the first separation zone (12).

2. The method according to claim 1, further comprising: Heat is transferred from the fifth stream (58) to the feed stream (10) in a third heat transfer zone (64).

3. The process according to claim 1, wherein the first separation zone (12) comprises a separation column (14).

4. The method according to claim 3, wherein the first heat transfer zone (32) is inside the separation column (14).

5. The method of claim 4, wherein transferring heat from the fifth stream (58) to the first separation zone (12) in the first heat transfer zone (32) comprises transferring heat to liquid within the column (14).

6. The method according to any one of claims 1 to 5, wherein the first heat transfer zone (32) comprises an inserted heat exchanger (34).

7. The method of claim 6, wherein the separation column (14) comprises a liquid collector section (106) having a first riser (110) and a second riser (118), both of which extend above the liquid collector section (106), wherein the first riser (110) bypasses the inserted heat exchanger (34).

8. The method of claim 7, wherein the first riser (110) and the second riser (118) both transfer vapor to a combining space (120) above the liquid collector portion (106).

9. An apparatus for separating aromatic hydrocarbons from non-aromatic hydrocarbons, the apparatus comprising: a first separation zone (12) comprising a separation column (14) configured to receive a feed stream (10) comprising aromatic hydrocarbons and non-aromatic hydrocarbons and to provide a first stream (18) comprising the non-aromatic hydrocarbons and a second stream (28) comprising the aromatic hydrocarbons and a solvent; a second separation zone (40) comprising a separation column (42) configured to receive the second stream (28) and provide a third stream (44) comprising the aromatic hydrocarbons, a fourth stream (70) comprising the solvent, and a fifth stream (58) comprising the solvent, wherein the fourth stream (70) comprises a side draw stream; a first heat transfer zone (32) configured to transfer heat from the fifth stream (58) to the first separation zone (12), wherein the first heat transfer zone (32) is disposed within the separation column (14) in the first separation zone (12); a second heat transfer zone (72) configured to transfer heat from the fourth stream (70) to the feed stream (10); a third heat transfer zone (64) configured to transfer heat from the fifth stream (58) to the feed stream (10); a pipeline configured to convey the fifth stream (58) from the third heat transfer zone (64) to the separation column (14) in the first separation zone (12); and, A pipeline configured to convey the fourth stream (70) from the second heat transfer zone (72) to the separation column (14) in the first separation zone (12).

10. The device according to claim 9, wherein the first heat transfer zone (32) comprises an inserted heat exchanger (34).

Images