Apparatus for removing heavy hydrocarbons from feed

Abstract

An apparatus for removing heavy hydrocarbons from a feed may include a scrubbing column and a stabilizing column arranged such that a portion of a first stream output from the stabilizing column is fed to the scrubbing column for use as a reflux stream. The utility model provides an implementation scheme in which the scrubbing tower generates flow mainly containing methane (such as more than 85 mole percent of methane) and reduced heavy hydrocarbon, so that reduced operation cost and improved operation flexibility can be realized in downstream natural gas liquefaction operation.

Description

Technical Field

[0001] The utility model relates to a method and a system for treating a gas feed containing methane (for example, natural gas) to remove impurities from the feed (for example, removing heavy hydrocarbons with 5 or more carbon atoms in the gas feed, etc.). Background Art

[0002] Liquefied natural gas (LNG) contains methane (CH4) that is cooled and liquefied so that it is in a liquid state. Examples of systems and methods involving LNG can be found in the following patents: U.S. Patent Application Publication Nos. 2022 / 0178609 and 2016 / 0216030 and U.S. Patent No. 11,499,775. Utility Model Content

[0003] Cryogenic natural gas liquids (NGL) recovery plants and LNG plants are typically configured to remove some of the heavier hydrocarbon components from a natural gas feed that is frozen during cryogenic processing to liquefy the methane in the feed. Such conventional systems typically provide a feed containing methane for a liquefaction process that may require significant compression, which may generate substantial operating costs for the liquefaction process and also limit the manner in which such a liquefaction process can be arranged and configured. Described herein are embodiments of feed gas processing methods and feed gas processing apparatus that can allow for more efficient removal of heavy hydrocarbons from a feed while also reducing operating costs and providing improved operating flexibility for downstream liquid natural gas liquefaction processing of the feed.

[0004] The embodiments of the apparatus and method described herein can be configured so that the scrubber can be operated at a preselected pressure, which can be selected independently of the refrigeration demand for precooling via the feed precooling heat exchanger. The embodiment can be adjusted so that the vapor stream mainly containing methane output from the scrubber can be supplied to a liquefaction device (e.g., a liquefier, etc.) at an elevated pressure, which can reduce the power demand for downstream liquefaction of the output vapor stream. The embodiment of the method and the apparatus can be configured so that the feed is at ambient temperature (e.g., between 0°C and 40°C, between 20°C and 40°C, etc.).

[0005] In some embodiments, the feed comprising methane and heavy hydrocarbon impurities is supplied to a heat exchanger and then supplied to a scrubber. The scrubber can be configured to output a first vapor stream comprising methane and a second stream with heavy hydrocarbons. The second stream can be supplied to a stabilizing tower, which can be configured to output a first stream for forming a reflux stream that can be supplied to the scrubber and a second stream with heavy hydrocarbons to separate the heavy hydrocarbons from the feed. The first vapor stream comprising methane can be transmitted through a heat exchanger to help cool and / or form a reflux stream provided via a stabilizing tower, and the formed reflux stream is then supplied to the scrubber.

[0006] In some embodiments, a reflux accumulator vessel (e.g., a reflux accumulator drum) can be provided between the heat exchanger and the scrubber tower to hold the formed reflux stream such that a sufficient reflux supply can be provided to the scrubber tower pump that is used to supply reflux to the scrubber tower. In some embodiments, the reflux accumulator vessel can be positioned and configured to help protect the scrubber pump from cavitating the pump. In the same or other embodiments, the stabilizer tower and the scrubber tower can be arranged and configured such that the scrubber tower can operate at a pressure in the range of 45 bara to 65 bara and the stabilizer tower can operate at a pressure in the range of 15 bara to 30 bara. In other embodiments, other pressure ranges for the stabilizer tower and / or the scrubber tower can also be utilized such that the stabilizer tower operates at a different operating pressure range that is lower than the operating pressure range of the scrubber tower. The vapor stream output from the scrubber tower mainly contains methane (e.g., between 80 mole percent (mol%) methane and 95 mol% methane, between at least 85 mol% methane and less than 100 mol% methane, at least 75 mol% methane, at least 90 mol% methane, etc.) and can be at an elevated pressure.

[0007] In a first aspect, an apparatus is provided for removing heavy hydrocarbon impurities from a feed containing methane gas and heavy hydrocarbons having at least five carbon atoms. The apparatus can include a scrubber tower that is positioned and configured to receive the feed and output a first scrubber tower stream and a second scrubber tower stream. The second scrubber tower stream can contain the heavy hydrocarbons. The apparatus can further include a stabilizer tower that is positioned downstream of the scrubber tower to receive the second scrubber tower stream. The stabilizer tower can be configured to output a first stabilizer tower stream and a second stabilizer tower stream. The second stabilizer tower stream can contain the heavy hydrocarbons. The scrubber tower can be configured such that a portion of the first stabilizer tower stream is supplied to the scrubber tower to provide scrubber tower reflux.

[0008] In some embodiments, the scrubber tower can operate at an elevated pressure to provide a treated feed gas at an elevated pressure to supply the treated feed to a downstream LNG or NGL plant such that the downstream plant requires improved operating flexibility and reduced compression load. Some embodiments can be integrated into an LNG plant or an NGL plant or can be a separate pretreatment facility that can supply a treated feed to such plants.

[0009] Some embodiments can be adjusted such that an expander is not used to expand the feed to the scrubber tower. Some embodiments can be configured such that the operating pressure range of the scrubber tower is higher than the operating pressure range of the stabilizer tower.

[0010] In a second aspect, the apparatus can include a reflux accumulator vessel configured to receive a portion of a first stabilizing column stream supplied to a scrub column, store a scrub column reflux, and supply the scrub column reflux to the scrub column.

[0011] In a third aspect, the apparatus may include a heat exchanger positioned to cool at least a portion of the feed before it is fed to the scrubber, receive a first scrubber stream from the scrubber, and / or cool a portion of a first stabilizer stream that may be fed to the scrubber to form a scrubber reflux stream that may be fed to a reflux accumulator vessel. For example, the heat exchanger may be positioned to cool a first portion of the feed before it is fed to the scrubber, receive a first scrubber stream from the scrubber, and cool a portion of the first stabilizer stream that is fed to the scrubber to form a scrubber reflux stream that is fed to the scrubber to provide a scrubber reflux.

[0012] In a fourth aspect, the scrubber of the device can be positioned so that the second part of the feed or the third part of the feed can be transmitted through the intermediate reboiler to cool the part of the feed, and heat the liquid from the scrubber received by the intermediate reboiler to form a stripping vapor. The intermediate reboiler can be positioned so that the stripping vapor is exported to the scrubber. The intermediate reboiler can be positioned and arranged so that the second part of the feed or the third part of the feed exported from the intermediate reboiler can be supplied to the scrubber. For example, in some embodiments, a heat exchanger and a scrubber can be positioned so that the second part of the feed or the third part of the feed exported from the intermediate reboiler is combined with the first part of the feed and supplied to the scrubber.

[0013] In a fifth aspect, the device may include a pump positioned to drive the flow of the washing tower backflow to the washing tower. For example, an embodiment may include a reflux accumulator container positioned to receive a portion of the first stabilizing tower flow supplied to the washing tower, store the washing tower reflux and supply the washing tower reflux to the washing tower. Such embodiments may also include a pump positioned to drive the flow of the washing tower backflow from the reflux accumulator container to the washing tower. In such embodiments, the stabilizing tower may be configured to operate under a preselected stabilizing tower operating pressure range, and the washing tower may be configured to operate under a preselected washing tower operating pressure range greater than the preselected stabilizing tower operating pressure range.

[0014] In a sixth aspect, the apparatus may include a phase separator positioned to receive a first stabilizing column stream and output a vapor stream and a liquid stream. The phase separator may be positioned so that a portion of the liquid stream and the vapor stream may be fed to a scrubber to form a scrubber reflux for providing reflux to the scrubber.

[0015] In some embodiments, the heat exchanger can be positioned to receive a vapor stream from a phase separator and a first portion of a liquid stream from the phase separator. A portion of the first stable column stream supplied to the scrubber as a scrubber reflux may include a vapor stream from the phase separator and a first portion of a liquid stream from the phase separator. The heat exchanger can be constructed and positioned to cool a first portion of the feed before the feed is supplied to the scrubber, and cool a first portion of the vapor stream and the liquid stream to form a scrubber reflux stream for providing a scrubber reflux for supplying to the scrubber.

[0016] In addition, in some embodiments, the reflux accumulator vessel can be positioned to receive the scrubber reflux stream output from the heat exchanger, store the scrubber reflux, and supply the scrubber reflux to the scrubber and / or be positioned to drive a pump that flows the scrubber reflux from the reflux accumulator vessel to the scrubber. In such embodiments or in other embodiments, the stabilizing tower can be configured to operate at a preselected stabilizing tower operating pressure range, and the scrubber can be configured to operate at a preselected scrubber operating pressure range greater than the preselected stabilizing tower operating pressure range.

[0017] In a seventh aspect, the device according to the first aspect may include one or more features of the second aspect, the third aspect, the fourth aspect, the fifth aspect and / or the sixth aspect. Therefore, it should be understood that embodiments of the device may include other elements or features of different exemplary embodiments. For example, an embodiment may include one or more exemplary features of the exemplary embodiments discussed herein.

[0018] In an eighth aspect, the utility model provides a method for treating a feed gas comprising methane and heavy hydrocarbons having at least five carbon atoms. An embodiment of the method may include providing the feed to a scrubber operating at a preselected scrubber operating pressure range, and outputting a first scrubber stream and a second scrubber stream from the scrubber. The second scrubber stream may contain the heavy hydrocarbons.

[0019] The method may further include supplying the second scrubber stream to a stabilizer operating at a preselected stabilizer operating pressure range to output a first stabilizer stream and a second stabilizer stream. The second stabilizer stream may contain heavy hydrocarbons.

[0020] The method may further include supplying a portion of the first stabilizer stream to a scrubber to provide a scrubber reflux to the scrubber.

[0021] Embodiments of the apparatus may be configured to implement or utilize embodiments of the method. Embodiments of the method may be configured such that the treated feed can be provided as a first wash column stream to a suitable downstream plant at elevated pressure to reduce the compression load required by the downstream plant and provide improved operating flexibility. The downstream plant may be, for example, an LNG plant or an NGL plant.

[0022] In a ninth aspect, the method may include additional steps. For example, the method may further include feeding a first stabilizer column stream to a phase separator to form a vapor stream and a liquid stream, feeding a portion of the vapor stream and the liquid stream to a heat exchanger to form a wash column reflux, feeding the wash column reflux output from the heat exchanger to a reflux accumulator vessel, and feeding the wash column reflux from the reflux accumulator vessel to an upper section of the wash column. Additionally, the method may include feeding the first wash column stream to the heat exchanger as a cooling medium to facilitate cooling a portion of the vapor stream and the liquid stream fed to the heat exchanger to form a wash column reflux.

[0023] In a tenth aspect, a preselected wash column operating pressure range may be higher than a preselected stabilizer column operating pressure range. For example, the preselected wash column operating pressure range may be between 45 bara and 65 bara, and the preselected stabilizer column operating pressure range may be between 15 bara and 30 bara.

[0024] In an eleventh aspect, the method may include splitting the feed into different portions. For example, the method may include splitting the feed into a first portion and a second portion, feeding the first portion to a heat exchanger located upstream of the wash column, then mixing the first portion with the second portion and feeding the combined feed to the wash column.

[0025] As another example, the method may include splitting the feed into a first portion, a second portion, and a third portion, feeding the first portion to a heat exchanger located upstream of the wash column, then mixing the first portion with the second portion and feeding the combined feed to the wash column, and feeding the third portion to a lower section of the wash column.

[0026] As yet another example, the method may include splitting the feed into a first portion and a second portion, feeding the first portion to a heat exchanger located upstream of the wash column, feeding the first portion to the wash column, and feeding the second portion to a lower section of the wash column.

[0027] As yet another example, the method can include splitting a feed stream into a first portion, a second portion, and a third portion, feeding the first portion to a heat exchanger positioned upstream of a scrubber, mixing the first portion with the second portion and feeding the combined feed to the scrubber, and feeding the third portion to an intermediate reboiler to form stripping vapor for feeding to the scrubber before feeding the third portion to the scrubber.

[0028] Embodiments of the method can also include other steps related to processing different portions of the split feed. For example, the method can also include mixing the third portion with the second portion and / or the first portion before the first portion, the second portion, and the third portion of the feed are fed to the scrubber.

[0029] In a twelfth aspect, the method according to the eighth aspect can include one or more features of the ninth, tenth, and / or eleventh aspects. Thus, it should be understood that embodiments of the method can include other elements or features of different exemplary embodiments. For example, an embodiment can include one or more exemplary features of the exemplary embodiments discussed herein.

[0030] It should be appreciated that embodiments of the method and apparatus can utilize various conduit arrangements and process control elements. Embodiments can utilize sensors (e.g., pressure sensors, temperature sensors, flow sensors, concentration sensors, etc.), controllers, valves, pipelines, and other process control elements. Some embodiments can utilize, for example, an automated process control system and / or a distributed control system (DCS). Various conduit arrangements and process control systems can be utilized to meet a set of specific design criteria.

[0031] From the following detailed description of certain exemplary embodiments, other details, objects, and advantages of the present invention will become apparent, including methods for processing a gas feed containing methane (e.g., natural gas) to remove impurities from the feed, apparatuses for processing a gas feed containing natural gas to remove impurities from the feed gas, systems for processing a gas feed containing methane to remove impurities from the feed, and methods of making and using the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Exemplary embodiments of the present invention are shown in the drawings included herein, including methods for processing a gas feed containing methane (e.g., natural gas) to remove impurities (e.g., heavy hydrocarbons) from the feed, apparatuses for processing a gas feed containing natural gas to remove impurities from the feed gas, systems for processing a gas feed containing methane to remove impurities from the feed, and methods of making and using the same. It should be understood that the same reference numerals used in the drawings can identify the same components.

[0033] Figure 1It is a block diagram of a first exemplary embodiment of an apparatus for processing a gas feed containing methane to remove impurities from the feed gas. Figure 1 Also illustrated is a first exemplary embodiment of a method for processing a gas feed containing methane to remove impurities from the feed gas. Impurities present in the feed gas to be processed may include heavy hydrocarbons (e.g., hydrocarbons having five or more carbons, such as pentane, hexane, heptane, octane, etc.).

[0034] Figure 2 It is a flowchart illustrating an exemplary embodiment of a method for processing a methane-containing feed gas to remove impurities from the feed gas. Figure 1 The exemplary embodiments of the apparatus shown in Figure 2 can be adapted to implement the exemplary embodiments of the method shown in Detailed Description

[0035] Figure 1 Illustrated is an exemplary embodiment of an apparatus 1 for processing one or more feeds containing methane to remove impurities from the feeds. Impurities to be removed may include heavy hydrocarbons having five or more carbon atoms (e.g., pentane, hexane, heptane, benzene, etc.). These exemplary embodiments of apparatus 1 may utilize exemplary embodiments of a method for processing one or more gas feeds containing methane to remove impurities from the feeds. Examples of such methods can be found in Figure 1 and Figure 2 For examples of such methods.

[0036] The feed 100 may be a completely gaseous feed provided at an initial feed temperature. The initial feed temperature of the feed 100 may be ambient temperature (e.g., between 0 °C and 40 °C, about 25 °C, between -5 °C and 40 °C, etc.). For embodiments in which the feed contains natural gas (e.g., methane (CH4)), the feed 100 may be provided via a natural gas pipeline or other source of the feed 100. The feed 100 may also contain impurities, which may include ethane, propane, butane, and heavy hydrocarbons having five or more carbon atoms (e.g., C5+ hydrocarbons such as pentane, isopentane, hexane, benzene, heptane, toluene, octane, etc.). The feed 100 may also contain trace amounts of other gases, such as nitrogen and carbon dioxide.

[0037] In some embodiments, the feed 100 may mainly comprise methane. For example, in some embodiments, the feed may have methane between 75 mole percent (mol%) and 100 mol%, ethane between 1 mol% and 8 mol%, propane between 0.2 mol% and 3 mol%, and butane between 0.01 mol% and 0.5 mol%, and heavy hydrocarbons having five or more carbon atoms in an amount between 1 mol% and greater than 0 mol%. The feed may also comprise nitrogen between 0 mol% and 3 mol% and carbon dioxide between 0 mol% and 0.1 mol%. In some embodiments, the feed may also comprise hydrogen and / or other components.

[0038] The feed 100 may be split into multiple portions upstream of the heat exchanger 118, and the different portions may be routed to the scrubber 106 and / or the heat exchanger 118. For example, the feed 100 may be split into: a first portion 128 that is passed through the heat exchanger 118 for cooling therein; a second portion 130 that may be split from the first portion upstream of the heat exchanger 118 and passed to the scrubber 106; and a third portion 132 that is supplied as a lower section feed portion 132A to the scrubber 106 at the bottom section or lower section of the scrubber 106.

[0039] In an alternative embodiment (as Figure 1 shown by the dashed line), the third portion 132 may be passed through the intermediate reboiler 150 to be used as a heating medium to indirectly heat the fluid of the scrubber 106 supplied to the intermediate reboiler 150 such that the fluid may be vaporized and supplied to the scrubber 106 as a vapor ( Figure 1 shown by the dashed line). In the case where the third portion passes through the intermediate reboiler 150, the third portion may be output from the intermediate reboiler 150 and mixed with the second portion 130 and / or the first portion 128 for supply to the scrubber 106, or may be output from the intermediate reboiler 150 and supplied from the intermediate reboiler 150 to the scrubber 106.

[0040] The first portion, second portion, and third portion of the feed 100 may be split to include different feed flow rates. For example, the first portion may be the largest portion among the first portion, second portion, and third portion, and the second portion may be smaller or larger than the third portion. For example, the first portion may be between 50% and 80% of the feed 100. The second portion 130 may be between 45% and 5% of the feed 100, and the third portion 132 may be between 45% and 5% of the feed.

[0041] The first portion 128 can be passed through the heat exchanger 118 to be cooled to a preselected first portion cooling temperature within a preselected first portion scrubber feed temperature range. Examples of the preselected first portion scrubber feed temperature range can be between -20°C and -50°C or other suitable temperature ranges. After the cooled first portion 128 exits the heat exchanger 118, it can be fed to the upper section or the middle section of the scrubber 106. In some embodiments, the first portion 128 can be mixed with the second portion 130, and then the mixed first and second portions can be fed to the scrubber 106. In other embodiments, the first portion 128 can be fed to the scrubber 106 via a separate feed conduit, and the second portion 130 can also be fed to the scrubber 106 via a separate feed conduit.

[0042] The second portion 130 can be split from the first portion 128 and then fed to the upper section or the middle section of the scrubber 106 via a second portion feed conduit connected between the feed conduit and the scrubber 106. Optionally, the second portion 130 can be cooled to a preselected second portion scrubber feed temperature within a preselected second portion scrubber feed temperature range via the cooler 102 and then fed to the scrubber 106. Examples of the preselected second portion scrubber feed temperature range can be between -15°C and -45°C or other suitable temperature ranges.

[0043] The second portion cooler 102 (as shown by the dashed line in Figure 1 the figure) that can be positioned to cool the second portion can be a quench cooler, a mechanical quench cooler, or other types of coolers that can utilize a stream of refrigerant 134A as the cooling medium for cooling the second portion 130. For example, the refrigerant 134A can be liquid propane from a downstream LNG plant, a mixed refrigerant from a downstream LNG plant, a quenched gaseous methane or nitrogen stream from a downstream LNG plant, or other types of refrigerants or cooling media that can be output from a downstream liquefier or LNG plant, or can be other process gases from other process elements (e.g., waste streams from an air separation unit, etc.).

[0044] In other arrangements, the second portion cooler 102 may not be used. For example, the cooling of the first portion 128 provided from the heat exchanger 118 to be subsequently mixed with the second portion 130 may be sufficient to also adequately cool the second portion 130 such that the mixed feed of the first portion 128 and the second portion 130 can be fed to the scrubber 106 at a suitable scrubber feed temperature. For example, a cooling medium stream 134B ( Figure 1is supplied (shown in dashed lines) to the heat exchanger 118 as a cooling medium to help cool the first portion 128 sufficiently via the heat exchanger 118 such that the mixed stream of the first portion 128 and the second portion 130 formed downstream of the heat exchanger 118 is at a suitable feed temperature for the scrubbing column 106.

[0045] Alternatively, cooling can be provided via the cooling medium stream 134B supplied to the heat exchanger 118 and / or the first scrubbing column stream 104 such that no second portion 130 of the feed is formed, but rather only the first portion 128 and the third portion 132 are formed. In such an arrangement where no second portion 130 is formed, the third portion 132 can be considered the second portion of the feed 100 and can be supplied as a lower section feed portion 132A to the lower section of the scrubbing column, or to the intermediate reboiler 150 and then to the scrubbing column 106 and / or mixed with the first portion 128 for supply to the scrubbing column 106.

[0046] For example, the cooling medium stream 134B ( Figure 1 shown in dashed lines) can be liquid propane from an LNG plant or other types of refrigerants or cooling media that can be output from a downstream liquefier or LNG plant, or can be other process gases from other process elements (e.g., waste streams from an air separation unit, etc.). For example, the cooling medium stream 134B can be liquid propane from a downstream LNG plant, a mixed refrigerant from a downstream LNG plant, a quenched gaseous methane or nitrogen stream from a downstream LNG plant, or other types of refrigerants or cooling media that can be output from a downstream liquefier or LNG plant, or can be other process gases from other process elements (e.g., waste streams from an air separation unit, etc.). Other embodiments can also utilize other refrigerant sources as the cooling medium 134B.

[0047] Embodiments that can use the cooling medium 134B from an external source (e.g., other plant processes, liquefiers, etc.) can be adjusted to provide cooling without reducing or lowering the scrubbing column pressure. This can allow the scrubbing column 106 to operate at a higher pressure to provide the treated stream 126 at an elevated pressure, which in turn can help avoid the use of an expander (e.g., expansion of the feed 100) and the pressure reduction associated with the use of an expander.

[0048] The scrubber 106 can receive a first portion 128, a second portion 130, and a third portion 132 of the feed 100, scrub the feed to remove heavy hydrocarbons therefrom, and output a first scrubber stream 104, which may also be considered a treated feed stream 104 or a scrubber vapor stream 104. The first scrubber stream 104 can be output from the top of the scrubber or from an upper section adjacent to the scrubber 106 as a vapor stream that is entirely gaseous. The scrubber 106 can also output a second scrubber stream 108 at the bottom of the scrubber or adjacent to the bottom (e.g., at a lower section of the scrubber 106).

[0049] The scrubber 106 can include a reboiler 136 that is positioned to strip methane and ethane from the second scrubber stream 108 at the bottom of the scrubber 106 or from the scrubber 106 such that the stripped methane and ethane can be returned to the scrubber 106 and the second stream 108 can be output as the second scrubber stream 108, which mainly contains heavy hydrocarbons with a relatively small amount of methane and ethane. In some embodiments, the second scrubber stream 108 can contain greater than 0 mol% and less than 20 mol% of methane, and greater than 0 mol% and less than 20 mol% of ethane. The remainder of the second scrubber stream 108 can contain heavy hydrocarbons, propane, butane, and other impurities from the feed 100. In some embodiments, the second scrubber stream 108 can contain heavy hydrocarbons between 30 mol% and 50 mol% or between 20 mol% and 40 mol%.

[0050] As described above, the scrubber 106 can also include an optional intermediate reboiler 150 that can use the third portion 132 as a heating medium to evaporate condensate or liquid from the lower section of the scrubber 106 and then supply it back to the scrubber 106 as stripping vapor for use therein.

[0051] The scrubber 106 can be arranged and configured such that it can operate within a preselected scrubber pressure range. This pressure range can be selected to provide the first scrubber stream 104 at an elevated pressure. In some embodiments, the preselected scrubber pressure range can be between 45 bara and 65 bara. Other embodiments can utilize other suitable pressure ranges of the preselected scrubber pressure range to meet a set of specific design criteria.

[0052] The second wash column stream 108 can be output from the wash column 106 and supplied to the stabilizer feed cooler 140. The stabilizer feed cooler 140 can be positioned between the wash column 106 and the stabilizer 110 to cool the second wash column stream 108 to a preselected stabilizer feed temperature. The stabilizer feed cooler 140 can be a quench cooler or a heat exchanger that can utilize ambient air or quench water cooling medium or other suitable cooling medium to cool the second wash column stream 108 to the preselected stabilizer feed temperature. In some embodiments, the temperature can be in the range of 0 °C to 30 °C or -5 °C to 40 °C.

[0053] The second wash column stream 108 can be supplied to the stabilizer 110 to form a first stabilizer stream 111 that can be output at the top or adjacent upper portion of the first stabilizer 110 and a second stabilizer stream 112 that can be output at the bottom or adjacent lower portion of the second stabilizer 110.

[0054] The stabilizer 110 can be operated at a preselected stabilizer pressure range. The preselected stabilizer pressure range can be selected such that the stabilizer 110 can output a suitable first stabilizer stream 111 to be supplied as reflux to the wash column 106. The stabilizer operating pressure range can be selected such that it is lower than the operating pressure range of the wash column 106. In some embodiments, the preselected stabilizer pressure range can be, for example, between 15 bara and 30 bara. Other embodiments can utilize other suitable pressure ranges of the preselected stabilizer pressure range to meet a set of specific design criteria.

[0055] In embodiments or implementations where it is desired to maximize the liquid phase fraction of the top product from the stabilizer 110 (e.g., the flow rate of stream 114 divided by the flow rate of stream 116), the stabilizer 110 can be operated at the highest possible pressure. However, the operating pressure of the stabilizer 110 may be limited by the maximum feasible operating temperature of the stabilizer reboiler 110A to prevent coke formation, since the operating temperature of the reboiler 110A may increase with pressure. In some embodiments, the highest temperature of the stabilizer reboiler 110A can be 200 °C or about 200 °C (e.g., 185 °C to 205 °C). However, the maximum operating pressure of the wash column 110 can depend on the composition of the stabilizer bottom product (e.g., the second stabilizer stream 112), which can vary based on the composition of the feed 100 and / or the composition of the second wash column stream 108 supplied to the stabilizer 110. In some embodiments, an operating pressure of the stabilizer 110 between 30 bara and 15 bara can often be used to help provide a configuration that promotes the maximization of the liquid phase fraction of the top product from the stabilizer 110. However, based on the expected stabilizer feed composition and the composition of the second stabilizer stream 112, other operating pressure ranges can also be used in different embodiments.

[0056] The stabilizer tower 110 may include a reboiler 110A that may be positioned and configured to strip methane and ethane from a second stabilizer tower stream 112 from the stabilizer tower 110 or the bottom of the stabilizer tower 110 such that the stripped methane and ethane may be returned to the stabilizer tower 110 and the second stabilizer tower stream 112 may be output as a stream predominantly containing heavy hydrocarbons with a relatively small amount of methane and ethane. In some embodiments, the second stabilizer tower stream 112 may contain between 0 mol% and 3 mol% of methane and between 0 mol% and 3 mol% of ethane. The remainder of the second stabilizer tower stream 112 may contain heavy hydrocarbons and may also contain trace amounts of other impurities from the feed 100 (e.g., trace amounts of propane, butane between 0 mol% and 3 mol%, etc.). In some embodiments, the second stabilizer tower stream 112 may contain between 100 mol% and 95 mol% of heavy hydrocarbons or between 90 mol% and 100 mol% of heavy hydrocarbons.

[0057] The first stabilizer tower stream 111 may predominantly contain light hydrocarbons (e.g., methane, ethane, propane, and butane) or may contain only such light hydrocarbons. For example, in some embodiments, the first stabilizer tower stream 111 may contain between 15 mol% and 40 mol% of methane, between 10 mol% and 40 mol% of ethane, between 10 mol% and 40 mol% of propane, and between 5 mol% and 15 mol% of butane. Other embodiments may be configured to utilize other concentration ranges of light hydrocarbons.

[0058] The first stabilizer tower stream 111 may be supplied to a first stabilizer tower stream cooling device 142. The cooling device may be an ambient air heat exchanger, a quench cooler, or other suitable type of cooling device for cooling the first stabilizer tower stream 111 to a preselected phase separator feed temperature that may be within a suitable preselected phase separator feed temperature range. The cooled first stabilizer tower stream 111 may contain liquid and gas and may be supplied to a phase separator 146 that may output a vapor stream 116 and a liquid stream 113.

[0059] In some embodiments, the vapor stream 116 can comprise between 15 mol% and 40 mol% methane, between 10 mol% and 40 mol% ethane, between 10 mol% and 40 mol% propane, and between 5 mol% and 15 mol% butane. The liquid stream 113 can comprise between 0 mol% and 10 mol% methane, between 5 mol% and 25 mol% ethane, between 15 mol% and 40 mol% propane, and between 20 mol% and 50 mol% butane. Other embodiments can be configured to utilize other component concentration ranges of the light hydrocarbons of the vapor stream 116 and the liquid stream 113.

[0060] The liquid stream 113 can be split such that a first portion 114 of the liquid stream is supplied to the first heat exchanger 118 and / or the reflux accumulator vessel 120 for forming a wash column reflux, and a second portion 115 is supplied to an upper section of the stabilizer column 110 as a reflux stream for the stabilizer column 110. The pump 144 can be positioned to facilitate the supply of the first portion 114 and the second portion 115 of the liquid stream 113 to the stabilizer column 110 and the reflux accumulator vessel 120.

[0061] A first portion 114 of the liquid stream 113 output from the phase separator 146 can be supplied to the heat exchanger 118 together with the vapor stream 116 such that these streams can distributively pass through the heat exchanger 118 together and the vapor can be cooled into a liquid form such that the combined vapor stream 116 and the first portion 114 of the liquid stream 113 can form a wash column reflux, which is output from the heat exchanger 118 as a wash column reflux stream 148. The wash column reflux stream 148 can comprise a liquid or can be a liquid, and can be supplied to the reflux accumulator vessel 120 for storage therein and then supplied as a wash column reflux feed stream 124 from the reflux accumulator vessel 120 to an upper portion of the wash column 106. The wash column reflux feed pump 122 can be configured to facilitate the flow of the wash column reflux feed stream 124 from the reflux accumulator vessel 120 to the upper portion of the wash column 106. In some embodiments, the reflux accumulator vessel 120 can be positioned, sized, and configured to help protect the wash column reflux feed pump 122 from cavitating the pump.

[0062] The first wash column stream 104 can also be passed through the first heat exchanger 118 to be used as a cooling medium therein. The heated first wash column stream 104 can be output from the first heat exchanger 118 as a treated feed stream 126 for supply to an NGL recovery plant or an LNG plant.

[0063] The processed feed stream 126 can be output at a preselected LNG plant feed temperature or other suitable temperature within a preselected processed feed stream temperature range. In some embodiments, the preselected processed feed stream temperature range can be between 0 °C and 40 °C, or between -10 °C and 25 °C, or other suitable ranges. The processed feed stream 126 can also be at a preselected processed feed stream pressure within a preselected processed feed stream pressure range. The preselected processed feed stream pressure range can be from 50 bara to 60 bara, 40 bara to 65 bara, or other suitable pressure ranges. The preselected processed feed stream pressure can be an elevated pressure suitable for feeding the processed feed stream to a downstream LNG plant or liquefaction plant process. Such elevated pressure can provide improved downstream operating flexibility and also allow downstream operations to occur more efficiently and at lower cost (e.g., by reducing the compression load and compressor arrangements required for such processing, etc.).

[0064] In other embodiments, a cooling medium stream 134B can be provided to cool the first wash column stream 104 such that the stream can be output from the first heat exchanger 118 as the processed feed stream 126 at a lower pre-processed feed stream temperature range (e.g., a range less than -10 °C, between -20 °C and -100 °C, or other suitable ranges). Such cooling can be provided such that in addition to cooling the first portion 114 of the liquid stream 113 for mixing with the vapor stream 116 and the first portion 128 of the feed, the first wash column stream 104 can be cooled.

[0065] It should be understood that conduits (including valves and other conduit elements) can be positioned to facilitate the flow of a stream and / or portions of a stream from one element of the method or apparatus to another. For example, the heat exchanger output conduit can be positioned between the heat exchanger 118 and the wash column 106 to transfer the first portion 128 of the feed output from the heat exchanger 118 to the wash column 106. As another example, a second portion conduit and a third portion conduit can be positioned between the feed conduit through which the feed 100 passes and the wash column 106 to feed the second and third portions of the feed to the wash column 106. As another example, the stabilizer feed conduit can be positioned between the stabilizer feed cooler 140 and the stabilizer 110 to transfer the cooled second wash column stream 108 from the stabilizer feed cooler 140 to the stabilizer 110, and there can be a stabilizer cooler feed conduit positioned between the wash column and the stabilizer feed cooler 140 to feed the second wash column stream 108 to the stabilizer feed cooler 140.

[0066] In some other instances, there may be a first stabilizer feed conduit positioned between the first stabilizer stream cooling device 142 and the stabilizer 110 to transfer the first stabilizer stream 111 to the first stabilizer stream cooling device 142. There may also be a phase separator feed conduit positioned between the first stabilizer stream cooling device 142 and the phase separator 146 to supply the cooled first stabilizer stream to the phase separator 146. The first vapor stream conduit may be positioned between the phase separator 146 and the heat exchanger 118 to supply the first vapor stream 116 from the phase separator 146 to the heat exchanger 118. In addition, a first portion of the liquid stream conduit may be positioned between the phase separator 146 and the heat exchanger 118 to supply a first portion 114 of the liquid stream 113 to the heat exchanger 118 for mixing with the vapor stream 116 and supplying through the heat exchanger 118. There may also be a scrubber reflux accumulator feed conduit positioned between the reflux accumulator vessel 120 and the heat exchanger 118 such that the scrubber reflux stream 148 is supplied from the heat exchanger 118 to the reflux accumulator vessel 120. In addition, there may be a stabilizer reflux conduit positioned between the stabilizer 110 and the phase separator 146 such that a second portion 115 of the liquid stream 113 can be supplied to the stabilizer 110.

[0067] In yet another instance, there may be a scrubber reflux feed conduit positioned between the reflux accumulator vessel 120 and the scrubber 106 to supply the scrubber reflux feed stream 124 from the reflux accumulator vessel 120 to the scrubber 106. There may also be a stabilizer reflux conduit positioned between the phase separator 146 and the stabilizer 110 to supply a second portion 115 of the liquid stream 113 from the phase separator 146 to the stabilizer 110. As discussed above, one or more pumps may be positioned in communication with one or more of the conduits to assist in driving the fluid flow to different components (e.g., the stabilizer reflux drive pump 144 and the scrubber reflux fluid drive pump 122, etc.).

[0068] Figure 2 An exemplary method for processing a feed gas containing methane is illustrated. Embodiments of the method may facilitate the removal of heavy hydrocarbons from the feed gas. Embodiments of the apparatus described herein may utilize embodiments of the method.

[0069] In a first step S1, feed 100 can be supplied to a wash column 106 and a vapor stream can be output from the wash column 106 as a first wash column stream 104. In some embodiments, the first wash column stream 104 can be supplied to a heat exchanger 118 for cooling at least a portion of the feed 100 to a preselected wash temperature. A lower second wash column stream 108 can also be output from the wash column 106 as a liquid stream or a stream that is predominantly liquid. The lower second wash column stream 108 output from the wash column 106 can be supplied to a stabilizer column 110. The lower second wash column stream 108 can contain heavy hydrocarbons having five or more carbon atoms (e.g., in some embodiments, the second wash column stream 108 can contain heavy hydrocarbons between 30 mol% and 50 mol% or between 20 mol% and 40 mol%).

[0070] The wash column 106 can operate at a preselected wash column operating pressure that is higher than a preselected stabilizer column operating pressure. For example, in some embodiments, the wash column 106 can operate in a pressure range of 45 bara to 65 bara, and the stabilizer column 110 that receives the second wash column stream 108 can operate at a preselected stabilizer column pressure in the range of 15 bara to 30 bara.

[0071] In a second step S2, the stabilizer column 110 can produce a first stabilizer column stream 111, and a portion of the first stabilizer column stream 111 can be supplied to the heat exchanger 118 to be cooled therein and then supplied to the wash column as a reflux stream 124 (e.g., the cooled portion of the first stabilizer column stream 11 can be split via a phase separator 146 such that a portion of the stream is cooled and supplied to an accumulator vessel 120 and then supplied to the wash column 106 as a wash column reflux feed stream 124). A second stream containing heavy hydrocarbons having five or more carbon atoms can also be output as a second stabilizer column stream 112 to facilitate removal of heavy hydrocarbons from the treated feed 126, which is output from the unit 1 and supplied to an LNG plant or an NGL recovery plant for liquefaction.

[0072] In some embodiments, in the second step S2, the first stabilizer column stream 111 can be cooled to a phase separator feed temperature and supplied to the phase separator 146 to form a vapor stream 116 and a liquid stream 113. The liquid stream 113 can be split into: a first portion 114, which is supplied to the heat exchanger 118 to be used as reflux for the wash column 106; and a second portion 115, which is supplied to the stabilizer column 110 as a reflux stream for the stabilizer column 110.

[0073] Embodiments of the method may also include additional steps. For example, the method may include a third step S3, in which a portion of the first stream output from the stabilizer column 110 is cooled to form a wash column reflux and supplied to the wash column 106 (e.g., a vapor stream 116 and / or a first portion 114 of the liquid stream 113 output from the phase separator 146 may be cooled via the heat exchanger 118 to form a wash column reflux). The formed wash column reflux may also be supplied to the wash column 106 via the wash column reflux feed pump 122 and / or the reflux accumulator vessel 120, as discussed above.

[0074] As another example, at least a portion of the feed 100 may be cooled via the heat exchanger 118 to a preselected wash temperature and supplied to the wash column 106 for removing heavy hydrocarbons having five or more carbons (e.g., pentane, hexane, etc.). As can be appreciated from the above, this step of the method may include splitting the feed 100 into different portions and cooling the whole or most of the feed, while a third portion 132 (or a second portion if no second portion 130 is formed) may not be cooled and may be supplied as a lower section feed portion 132A to the lower section of the wash column 106. In some embodiments, the third portion 132 may be used as a heating medium to form stripping vapor, which is supplied to the lower section of the wash column and then mixed with the second portion 130 and / or the first portion 128 and supplied to the wash column 106, such that all portions of the feed 100 that may be split from the feed 100 are cooled and then supplied to the wash column 106. It should also be understood that in embodiments where no second portion 130 is formed, the third portion 132 split from the feed 100 may be regarded as the second portion of the feed rather than the third portion of the feed.

[0075] Embodiments of the methods and apparatuses described herein may be configured to provide a treated feed stream 126 that is completely free or nearly completely free of heavy hydrocarbons (e.g., containing only trace amounts of heavy hydrocarbons having five or more carbon atoms). The treated feed stream 126 may be provided at a preselected treated feed stream pressure within a preselected treated feed stream pressure range. The preselected treated feed stream pressure range may be from 50 bara to 60 bara, 40 bara to 65 bara, or other suitable pressure ranges, and the pressure range may be selected to provide an elevated pressure for the treated feed stream 126 such that the treated feed stream 126 may be supplied to a downstream LNG plant or liquefaction plant process (e.g., a liquefier). Such elevated pressure may provide improved downstream operating flexibility and also allow downstream operations to occur more efficiently and at lower cost (e.g., by reducing the compression load and compressor arrangement required for such treatment).

[0076] It should be understood that the embodiments explicitly shown and discussed herein can be modified to meet a set of specific design objectives or a set of specific design criteria. For example, the arrangement of valves, pipelines, and other conduit elements (e.g., conduit connection mechanisms, pipes, seals, valves, etc.) for interconnecting different units of a device and providing fluid flow between different elements (e.g., pumps, heat exchangers, cooling equipment, quenchers, compressors, etc.) can be arranged to meet a specific plant layout design that takes into account the available area of the plant, the design of the equipment size in the plant, and other design considerations. As another example, the flow rate, pressure, and temperature of the fluid conveyed through various device or system elements can be varied to account for different design configurations and other design criteria.

[0077] Embodiments of an apparatus for processing a gas feed containing methane to remove impurities from the feed, a method for processing a gas feed containing methane to remove impurities from the feed, and / or a system for processing a gas feed containing methane to remove impurities from the feed can each be configured to include process control elements (e.g., temperature sensors and pressure sensors, flow sensors, an automated process control system having at least one workstation including a processor, a non-transitory storage, and at least one transceiver for communicating with sensor elements, valves, and controllers, providing a user interface for an automated process control system that can operate at the workstation and / or another computer device in the plant, etc.) that are positioned and configured to monitor and control operations. It should be understood that the embodiments can also utilize a distributed control system (DCS) to implement one or more processing and / or control operations of the device.

[0078] As another example, it is contemplated that specific features described separately or as part of an embodiment can be combined with other separately described features or parts of other embodiments. The elements and actions of the various embodiments described herein can thus be combined to provide further embodiments. Therefore, although certain exemplary embodiments of methods, apparatuses, systems, and methods of their manufacture and use have been shown and described above, it should be clearly understood that the present utility model is not limited thereto, but can be otherwise implemented and practiced within the scope of the appended claims.

Claims

1. An apparatus for removing heavy hydrocarbons from a feed comprising methane gas and hydrocarbons having at least five carbon atoms, the apparatus comprising: a scrubber positioned and configured to receive the feed and output a first scrubber stream and a second scrubber stream, the second scrubber stream comprising the hydrocarbons having at least five carbon atoms; a stabilizer positioned downstream of the scrubber to receive the second scrubber stream and configured to output a first stabilizer stream and a second stabilizer stream, the second stabilizer stream comprising the hydrocarbons having at least five carbon atoms, wherein the wash column is positioned such that a portion of the first stabilizer column stream is fed to the wash column as a wash column reflux stream.

2. The device for removing heavy hydrocarbons from a feed according to claim 1, comprising: A reflux accumulator vessel is positioned to receive the scrubber reflux stream, store the scrubber reflux stream, and supply the scrubber reflux stream to the scrubber.

3. The device for removing heavy hydrocarbons from a feed according to claim 2, comprising: A heat exchanger is positioned to cool at least a portion of the feed before it is supplied to the scrubber, receive the first scrubber stream from the scrubber, and cool the scrubber reflux stream before it is supplied to the reflux accumulator vessel.

4. The device for removing heavy hydrocarbons from a feed according to claim 1, comprising: A heat exchanger is positioned to cool a first portion of the feed before the feed is supplied to the scrubber, receive the first scrubber stream from the scrubber, and cool the scrubber reflux stream before the scrubber reflux stream is supplied to the scrubber.

5. An apparatus for removing heavy hydrocarbons from a feed according to claim 4, wherein the scrubbing tower is positioned so that the second portion of the feed or the third portion of the feed is passed through an intermediate reboiler of the scrubbing tower to cool that portion of the feed and to heat the liquid from the scrubbing tower to form a stripping vapor, and the intermediate reboiler is positioned to output the stripping vapor to the scrubbing tower.

6. The apparatus for removing heavy hydrocarbons from a feed according to claim 5, wherein the heat exchanger and the wash tower are positioned so that the second portion of the feed or the third portion of the feed cooled in the intermediate reboiler is combined with the first portion of the feed and supplied to the wash tower.

7. The apparatus for removing heavy hydrocarbons from a feed according to claim 5, wherein the intermediate reboiler is positioned and arranged so that the second portion of the feed or the third portion of the feed cooled in the intermediate reboiler is supplied to the wash column.

8. The apparatus for removing heavy hydrocarbons from a feed according to claim 1, further comprising: a reflux accumulator vessel positioned to receive the portion of the first stabilizer stream fed to the scrubber, store the scrubber reflux stream, and feed the scrubber reflux stream to the scrubber; as well as a pump positioned to drive flow of the wash column reflux flow from the reflux accumulator vessel to the wash column; wherein the stabilizer tower is configured to operate at a preselected stabilizer tower operating pressure range, and the scrubber tower is configured to operate at a preselected scrubber tower operating pressure range greater than the preselected stabilizer tower operating pressure range.

9. The apparatus for removing heavy hydrocarbons from a feed according to claim 1, further comprising: A phase separator is positioned to receive the first stabilizer column stream and output a vapor stream and a liquid stream.

10. The apparatus for removing heavy hydrocarbons from a feed according to claim 9, comprising: a heat exchanger positioned to receive the vapor stream from the phase separator and a first portion of the liquid stream from the phase separator; wherein the portion of the first stabilizer stream supplied to the wash column as the wash column reflux stream comprises the vapor stream from the phase separator and the first portion of the liquid stream from the phase separator; and The heat exchanger is constructed and positioned to cool a first portion of the feed before the feed is supplied to the scrubber column and to cool the scrubber column reflux stream before the scrubber column reflux stream is supplied to the scrubber column.

11. The apparatus for removing heavy hydrocarbons from a feed according to claim 10, further comprising: a reflux accumulator vessel positioned to receive the scrubber reflux stream from the heat exchanger, store the scrubber reflux stream, and supply the scrubber reflux stream to the scrubber; as well as a pump positioned to drive flow of the wash column reflux flow from the reflux accumulator vessel to the wash column; wherein the stabilizer tower is configured to operate at a preselected stabilizer tower operating pressure range, and the scrubber tower is configured to operate at a preselected scrubber tower operating pressure range greater than the preselected stabilizer tower operating pressure range.

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