Apparatus and process for removing heavy hydrocarbons from feed gas

Abstract

An apparatus and process for removing heavy hydrocarbons (e.g., hydrocarbons comprising five or more carbons, such as pentane and hexane, etc.) from a feed (e.g., a feed comprising methane and impurities) may include a scrubbing column and a stabilization column, the scrubbing tower and the stabilization tower are arranged such that a portion of the first stream output from the stabilization tower is supplied to the scrubbing tower as a reflux stream. Embodiments are provided in which the scrubbing column produces a stream comprising predominantly methane (e.g., more than 85 mole percent methane) and reduced heavy hydrocarbons, such that reduced operating costs and improved operating flexibility can be achieved in downstream natural gas liquefaction operations.

Description

Technical Field

[0001] The present invention relates to methods and systems for treating a gas feed containing methane (eg, natural gas) to remove impurities from the feed (eg, to remove heavy hydrocarbons having 5 or more carbons within 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. Summary of the invention

[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 container (for example, a reflux accumulator bucket) can be provided between heat exchanger and washing tower to retain the formed reflux flow, so that enough reflux supplies can be provided to the washing tower pump for providing reflux to washing tower. In some embodiments, the reflux accumulator container can be positioned and configured to help protect the washing pump to avoid cavitation of the pump. In the same or other embodiments, stabilizing tower and washing tower can be arranged and configured so that washing tower can be operated under a pressure within the range of 45bara to 65bara and stabilizing tower can be operated under a pressure within the range of 15bara to 30bara. In other embodiments, other pressure ranges for stabilizing tower and / or washing tower can also be utilized so that stabilizing tower is operated under different operating pressure ranges lower than the operating pressure range of washing tower. The vapor stream output from the scrubber column comprises primarily 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, a device for removing heavy hydrocarbon impurities from a feed containing methane gas and heavy hydrocarbons having at least five carbon atoms is provided. The device may include a scrubber positioned and configured to receive the feed and output a first scrubber stream and a second scrubber stream. The second scrubber stream may contain the heavy hydrocarbons. The device may also include a stabilizer positioned downstream of the scrubber to receive the second scrubber stream. The stabilizer may be configured to output a first stabilizer stream and a second stabilizer stream. The second stabilizer stream may contain the heavy hydrocarbons. The scrubber may be configured so that a portion of the first stabilizer stream is supplied to the scrubber to provide a scrubber reflux.

[0008] In some embodiments, the scrubber may be operated at an elevated pressure to provide a treated feed gas at an elevated pressure to provide the treated feed to a downstream LNG or NGL plant, such that the downstream plant requires improved operating flexibility and reduced compression loads. Some embodiments may be integrated into an LNG plant or NGL plant, or as a separate pre-treatment facility that can supply treated feed to such a plant.

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

[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 present invention provides a method for treating a feed gas comprising methane and heavy hydrocarbons having at least five carbon atoms. Embodiments 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 so that the treated feed may be provided as a first scrubber stream to a suitable downstream plant at elevated pressure to reduce the compression load required for the downstream plant and provide improved operational flexibility. The downstream plant may be, for example, an LNG plant or an NGL plant.

[0022] In the ninth aspect, the method may include additional steps. For example, the method may also include supplying the first stabilizing tower stream to a phase separator to form a vapor stream and a liquid stream, supplying a portion of the vapor stream and the liquid stream to a heat exchanger to form a scrubber reflux, supplying the scrubber reflux output from the heat exchanger to a reflux accumulator container, and supplying the scrubber reflux from the reflux accumulator container to an upper section of the scrubber. In addition, the method may include supplying the first scrubber stream to a heat exchanger as a cooling medium to facilitate cooling a portion of the vapor stream and the liquid stream supplied to the heat exchanger to form a scrubber reflux.

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

[0024] In an eleventh aspect, the method may include splitting the feed into different parts. For example, the method may include splitting the feed into a first part and a second part, and supplying the first part to a heat exchanger positioned upstream of a scrubber, then mixing the first part with the second part and supplying the combined feed to the scrubber.

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

[0026] As yet another example, the method can include splitting a feed into a first portion and a second portion, supplying the first portion to a heat exchanger positioned upstream of a scrubber column, supplying the first portion to the scrubber column, and supplying the second portion to a lower section of the scrubber column.

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

[0028] Embodiments of the method may also include other steps associated with processing different portions of the split feed. For example, the method may 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 supplied to the scrubbing column.

[0029] In the twelfth aspect, the method according to the eighth aspect may include one or more features of the ninth aspect, the tenth aspect, and / or the eleventh aspect. Therefore, it should be understood that the embodiment of the method 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.

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

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

[0032] Exemplary embodiments of the invention are shown in the drawings included herein, including methods for treating a gas feed containing methane (e.g., natural gas) to remove impurities (e.g., heavy hydrocarbons) from the feed, apparatus for treating a gas feed containing natural gas to remove impurities from the feed gas, systems for treating 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 may identify the same components.

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

[0034] Figure 2 is a flow chart illustrating an exemplary embodiment of a method for treating a feed gas comprising methane to remove impurities from the feed gas. Figure 1 The exemplary embodiment of the apparatus shown in FIG. 1 may be adapted to implement Figure 2 An exemplary embodiment of the method shown in . DETAILED DESCRIPTION

[0035] Figure 1 Exemplary embodiments of an apparatus 1 for treating one or more feeds containing methane to remove impurities from the feeds are illustrated. The 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 the apparatus 1 may utilize exemplary embodiments of a method for treating one or more gaseous feeds containing methane to remove impurities from the feeds. Figure 1 and Figure 2 See examples of this approach.

[0036] Feed 100 can be a completely gaseous feed provided at an initial feed temperature. The initial feed temperature of feed 100 can 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 comprises natural gas (e.g., methane (CH4)), the feed can be provided via a natural gas pipeline or other sources of feed 100. Feed 100 can also include impurities, which can include ethane, propane, butane, and heavy hydrocarbons with five or more carbon atoms (e.g., C5+ hydrocarbons, such as pentane, isopentane, hexane, benzene, heptane, toluene, octane, etc.). Feed 100 can also include trace amounts of other gases, such as nitrogen and carbon dioxide.

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

[0038] The feed 100 may be split into a plurality of portions upstream of the heat exchanger 118, and 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, which is passed through the heat exchanger 118 to be cooled therein; a second portion 130, which may be split from the first portion upstream of the heat exchanger 118 and passed to the scrubber 106; and a third portion 132, which is fed to the scrubber at the bottom section or lower section of the scrubber 106 as a lower section feed portion 132A.

[0039] In alternative embodiments (such as Figure 1 In the embodiment shown in the dashed line in the figure, the third part 132 can be transmitted through the intermediate reboiler 150 to be used as a heating medium to indirectly heat the fluid of the scrubbing tower 106 supplied to the intermediate reboiler 150, so that the fluid can be vaporized and supplied from the intermediate reboiler 150 to the scrubbing tower 106 as a vapor ( Figure 1 In the case where the third portion is passed 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 to the scrubber 106 from the intermediate reboiler 150.

[0040] The first, second, and third portions of feed 100 may be split to include different feed flow rates. For example, the first portion may be the largest portion of the first, second, and third portions, 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 feed 100. Second portion 130 may be between 45% and 5% of feed 100, and third portion 132 may be between 45% and 5% of the feed.

[0041] The first portion 128 can be conveyed through the heat exchanger 118 to be cooled to a preselected first portion cooling temperature within a preselected first portion wash column feed temperature range. An example of a preselected first portion wash column feed temperature range can be between -20°C and -50°C or other suitable temperature range. After the cooled first portion 128 is output from the heat exchanger 118, it can be supplied to the upper section or the middle section of the wash column 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 supplied to the wash column 106. In other embodiments, the first portion 128 can be supplied to the wash column 106 via a separate feed conduit, and the second portion 130 can also be supplied to the wash column 106 via a separate feed conduit.

[0042] The second portion 130 may be split from the first portion 128 and subsequently supplied 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. The second portion 130 may optionally be cooled via the cooler 102 to a preselected second portion scrubber feed temperature within a preselected second portion scrubber feed temperature range before being supplied to the scrubber 106. An example of a preselected second portion scrubber feed temperature range may be between -15°C and -45°C or other suitable temperature ranges.

[0043] A second portion cooler 102 (eg, Figure 1 The second portion 130 may be a chiller, a mechanical chiller, or other type of cooler that can utilize a flow of refrigerant 134A as a cooling medium for cooling the second portion 130. For example, the refrigerant 134A may be liquid propane from a downstream LNG plant, a mixed refrigerant from a downstream LNG plant, a chilled gaseous methane or nitrogen stream from a downstream LNG plant, or other types of refrigerants or cooling media that may be output from a downstream liquefier or LNG plant, or may be other process gases from other process elements (e.g., a waste stream from an air separation unit, etc.).

[0044] In other arrangements, the second portion cooler 102 may not be used. For example, the cooling from the heat exchanger 118 provided to the first portion 128, which is then mixed with the second portion 130, may be sufficient to cool the second portion 130 sufficiently so that the combined feed of the first portion 128 and the second portion 130 can be supplied to the scrubber 106 at a suitable scrubber feed temperature. For example, the cooling medium stream 134B ( Figure 1The first part 128 is supplied to the heat exchanger 118 as a cooling medium to help sufficiently cool the first part 128 via the heat exchanger 118 so that the mixed flow of the first part 128 and the second part 130 formed downstream of the heat exchanger 118 is at a suitable feed temperature for the washing tower 106.

[0045] Alternatively, cooling may be provided via cooling medium stream 134B supplied to heat exchanger 118 and / or first scrubber stream 104, such that second portion 130 of the feed is not formed, but rather only first portion 128 and third portion 132 are formed. In such an arrangement where second portion 130 is not formed, third portion 132 may be considered a second portion of feed 100, and may be supplied to the lower section of the scrubber as lower section feed portion 132A, or to intermediate reboiler 150, and then to scrubber 106 and / or mixed with first portion 128 for supply to scrubber 106.

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

[0047] Embodiments that can use 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 scrubber pressure. This can allow the scrubber 106 to operate at a higher pressure to provide a treated stream 126 at an elevated pressure, which in turn can help avoid the use of an expander (e.g., expansion of feed 100) and the pressure reduction associated with the use of an expander.

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

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

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

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

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

[0053] The second scrubber stream 108 may be fed to a stabilizer 110 to form a first stabilizer stream 111 that may be output at the top or adjacent an upper portion of the first stabilizer 110 and a second stabilizer stream 112 that may be output at the bottom or adjacent a 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 so that the stabilizer 110 can output a suitable first stabilizer stream 111 to be supplied to the scrubber 106 as a reflux of the scrubber 106. The stabilizer operating pressure range can be selected so that it is lower than the operating pressure range of the scrubber 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 specific set of 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 may be operated at as high a pressure as possible. 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, because the operating temperature of the reboiler 110A may increase with pressure. In some embodiments, the maximum temperature of the stabilizer reboiler 110A may be 200° C. or about 200° C. (e.g., 185° C. to 205° C.). However, the maximum operating pressure of the scrubber 110 may depend on the composition of the stabilizer bottom product (e.g., the second stabilizer stream 112), which may vary based on the composition of the feed 100 and / or the composition of the second scrubber stream 108 supplied to the stabilizer 110. In some embodiments, an operating pressure of between 30 bara and 15 bara for the stabilizer column 110 can often be used to help provide a configuration that promotes maximization of the liquid phase fraction of the overhead product from the stabilizer column 110. However, other operating pressure ranges can also be used in different embodiments based on the desired stabilizer feed composition and the composition of the second stabilizer stream 112.

[0056] The stabilizer 110 may include a reboiler 110A that may be positioned and configured to strip methane and ethane from a second stabilizer stream 112 from the stabilizer 110 or the bottom of the stabilizer 110, so that the stripped methane and ethane may be returned to the stabilizer 110 and the second stabilizer stream 112 may be output as a stream containing mainly heavy hydrocarbons, with relatively small amounts of methane and ethane. In some embodiments, the second stabilizer stream 112 may contain methane between 0 mol% and 3 mol% and ethane between 0 mol% and 3 mol%. The remainder of the second stabilizer 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 stream 112 may contain heavy hydrocarbons between 100 mol% and 95 mol% or heavy hydrocarbons between 90 mol% and 100 mol%.

[0057] The first stabilizer stream 111 may contain primarily light hydrocarbons (e.g., methane, ethane, propane, and butane) or only such light hydrocarbons. For example, in some embodiments, the first stabilizer stream 111 may contain 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. Other embodiments may be configured to utilize other component concentration ranges of light hydrocarbons.

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

[0059] In some embodiments, vapor stream 116 may contain 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. Liquid stream 113 may contain 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 may be configured to utilize other component concentration ranges of light hydrocarbons of vapor stream 116 and liquid stream 113.

[0060] The liquid stream 113 may be split such that a first portion 114 of the liquid stream is fed to the first heat exchanger 118 and / or the reflux accumulation vessel 120 for forming a scrubber reflux, and a second portion 115 is fed to the upper section of the stabilizer column 110 as a reflux stream for the stabilizer column 110. A pump 144 may be positioned to facilitate feeding 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] The first portion 114 of the liquid stream 113 output from the phase separator 146 may be fed to the heat exchanger 118 together with the vapor stream 116 so that the streams may be distributed together through the heat exchanger 118 and the vapor may be cooled to liquid form so that the combined vapor stream 116 and the first portion 114 of the liquid stream 113 may form a scrubber reflux that is output from the heat exchanger 118 as a scrubber reflux stream 148. The scrubber reflux stream 148 may contain a liquid or may be a liquid and may be fed to the reflux accumulator vessel 120 for storage therein and subsequently fed from the reflux accumulator vessel 120 to the upper portion of the scrubber 106 as a scrubber reflux feed stream 124. The scrubber reflux feed pump 122 may be configured to facilitate the flow of the scrubber reflux feed stream 124 from the reflux accumulator vessel 120 to the upper portion of the scrubber 106. In some embodiments, the back accumulator vessel 120 may be positioned, sized, and configured to help protect the scrubber reflux feed pump 122 from cavitating the pump.

[0062] The first scrubber stream 104 may also be passed through the first heat exchanger 118 to be used as a cooling medium therein. The heated first scrubber stream 104 may 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 treated feed stream 126 can be output at a preselected LNG plant feed temperature or other suitable temperature within a preselected treated feed stream temperature range. In some embodiments, the preselected treated feed stream temperature range can be between 0°C and 40°C, or between -10°C and 25°C, or other suitable ranges. The treated feed stream 126 can also be at a preselected treated feed stream pressure within a preselected treated feed stream pressure range. The preselected treated feed stream pressure range can be from 50 bara to 60 bara, 40 bara to 65 bara, or other suitable pressure ranges. The preselected treated feed stream pressure can be an elevated pressure suitable for supplying the treated feed stream to a downstream LNG plant or liquefaction plant process. Such elevated pressures can provide improved downstream operational flexibility, and also allow downstream operations to occur more efficiently and at a lower cost (e.g., by reducing the compression load and compressor arrangement required for such processing, etc.).

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

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

[0066] In other examples, 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 wash column reflux accumulator feed conduit positioned between the reflux accumulator vessel 120 and the heat exchanger 118 such that the wash column reflux stream 148 is fed from the heat exchanger 118 to the reflux accumulator vessel 120. In addition, there may be a stabilizer column reflux conduit positioned between the stabilizer column 110 and the phase separator 146 such that a second portion 115 of the liquid stream 113 may be fed to the stabilizer column 110.

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

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

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

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

[0071] In the second step S2, the stabilizer 110 can produce a first stabilizer stream 111, and a portion of the first stabilizer stream 111 can be supplied to the heat exchanger 118 to be cooled therein, and then supplied to the scrubber as a reflux stream 124 (e.g., the cooled portion of the first stabilizer stream 11 can be split via the phase separator 146 so that a portion of the stream is cooled and supplied to the accumulator vessel 120, and then supplied to the scrubber 106 as a scrubber reflux feed stream 124). A second stream of heavy hydrocarbons containing five or more carbon atoms can also be output as a second stabilizer stream 112 to facilitate the removal of heavy hydrocarbons from the treated feed 126, which is output from the device 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 stream 111 may be cooled to a phase separator feed temperature and supplied to a phase separator 146 to form a vapor stream 116 and a liquid stream 113. The liquid stream 113 may be split into a first portion 114 supplied to a heat exchanger 118 for use as a reflux of the scrubbing column 106, and a second portion 115 supplied to the stabilizer column 110 as a reflux stream of the stabilizer column 110.

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

[0074] As another example, at least a portion of the feed 100 may be cooled to a preselected scrubbing temperature via the heat exchanger 118 and supplied to the scrubber 106 for removal of 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 diverting the feed 100 into different portions and cooling the entirety of the feed or a majority of the feed, while the third portion 132 (or the second portion if the second portion 130 is not formed) may not be cooled and may be supplied to the lower section of the scrubber 106 as the lower section feed portion 132A. In some embodiments, the third portion 132 may be used as a heating medium to form a stripping vapor to be supplied to the lower section of the scrubber, and then mixed with the second portion 130 and / or the first portion 128 and supplied to the scrubber 106, so that all portions of the feed 100 that may be diverted from the feed 100 are cooled and then supplied to the scrubber 106. It should also be appreciated that in embodiments where the second portion 130 is not formed, the third portion 132 diverted from the feed 100 may be considered the second portion of the feed rather than the third portion of the feed.

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

[0076] It should be understood that the embodiments clearly shown and discussed herein can be modified to meet a group of specific design goals or a group of specific design standards. For example, the arrangement of valves, pipelines and other conduit elements (for example, conduit connection mechanism, pipeline, seal, valve, etc.) is used for the different units of interconnection device, and the fluid flow between different elements (for example, pump, heat exchanger, cooling equipment, chiller, compressor, etc.) is provided, and the arrangement can be arranged to meet a specific plant layout design, and the plant layout design takes into account the available area of ​​the plant, the equipment size design of the plant and other design considerations. As another example, the flow, pressure and temperature of the fluid transmitted through various devices or system elements can change, to consider different design configurations and other design standards.

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

[0078] As another example, it is contemplated that a particular feature described individually or as part of an embodiment may be combined with other individually described features or parts of other embodiments. The elements and actions of the various embodiments described herein may therefore be combined to provide further embodiments. Therefore, although certain exemplary embodiments of methods, devices, systems, and methods of manufacture and use thereof have been shown and described above, it should be clearly understood that the present invention is not limited thereto, but may be implemented and practiced in other ways within the scope of the appended claims.

Claims

1. An apparatus for removing heavy hydrocarbon impurities 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 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 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 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. The apparatus of claim 1 , wherein the scrubber is positioned so that the second portion of the feed or the third portion of the feed passes through an intermediate reboiler of the scrubber to cool that portion of the feed and heat liquid from the scrubber to form a stripping vapor, the intermediate reboiler being positioned to output the stripping vapor to the scrubber.

6. The apparatus of claim 5, wherein the heat exchanger and the scrubber 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 scrubber.

7. The apparatus 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 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 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 device 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 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.

12. A method for treating a feed gas comprising methane and hydrocarbons having at least five carbon atoms, the method comprising: providing the feed gas to a scrubber operating at a preselected scrubber operating pressure range to output a first scrubber stream and a second scrubber stream from the scrubber, the second scrubber stream comprising the hydrocarbons having at least five carbon atoms; feeding 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 comprising the hydrocarbons having at least five carbon atoms; and A portion of the first stabilizer column stream is provided to the wash column to provide a wash column reflux stream to the wash column.

13. The method according to claim 12, comprising: feeding the first stabilizer column stream to a phase separator to form a vapor stream and a liquid stream; supplying the vapor stream and a portion of the liquid stream to a heat exchanger to form the scrubber reflux stream; supplying the scrubber reflux stream from the heat exchanger to a reflux accumulator vessel; and The wash column reflux stream from the reflux accumulator vessel is fed to an upper section of the wash column.

14. The method according to claim 13, comprising: The first scrubber stream is fed to the heat exchanger as a cooling medium to cool the portion of the vapor stream and the liquid stream fed to the heat exchanger to form the scrubber reflux stream.

15. The method of claim 12, wherein the preselected scrubber operating pressure range is between 45 bara and 65 bara, and the preselected stabilizer operating pressure range is between 15 bara and 30 bara.

16. The method according to claim 12, comprising: A feed is split into a first portion and a second portion, the first portion is supplied to a heat exchanger positioned upstream of the wash column, and the first portion exiting from the heat exchanger is mixed with the second portion before providing the feed to the wash column.

17. The method according to claim 12, comprising: splitting a feed into a first portion, a second portion, and a third portion, supplying the first portion to a heat exchanger positioned upstream of the scrubber, mixing the first portion exiting the heat exchanger with the second portion, and then providing a stream comprising the first portion and the second portion to the scrubber; and The third portion is fed to a section of the wash column which is lower than the section to which the stream comprising the first portion and the second portion is fed.

18. The method according to claim 12, comprising: splitting a feed into a first portion and a second portion, supplying the first portion to a heat exchanger positioned upstream of the wash column, and supplying the first portion exiting the heat exchanger to the wash column; and The second portion is fed to a section of the scrubber column which is lower than the section to which the first portion is fed.

19. The method according to claim 12, comprising: splitting a feed into a first portion, a second portion, and a third portion, supplying the first portion to a heat exchanger positioned upstream of the scrubber, mixing the first portion exiting the heat exchanger with the second portion, and then providing a stream comprising the first portion and the second portion to the scrubber; The third portion is fed to an intermediate reboiler to form a stripping vapor, and the stripping vapor is fed to the scrubber.

20. The method according to claim 19, comprising: Before supplying the first, second and third portions of the feed to the wash column, the third portion is mixed with the second portion and / or the first portion.

21. The method of claim 12, wherein the preselected stabilizer tower operating pressure range is lower than the preselected scrubber tower operating pressure range.

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