Integrated Membrane Separation Unit

Abstract

Disclosed herein is an integrated membrane separation unit having improved separation performance and incorporating a membrane module incorporating a hydrophilic membrane, a heat transfer module, and a sweep module containing water and water vapor. The sweep module can be configured to supply a sweep stream containing water vapor derived from the water to the permeate side of the membrane module. The temperature of the water can be maintained through contact with the heat transfer module and heat transfer from the inlet gas stream or wet feed stream to the water.

Description

[Background technology]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Application No. 63 / 399,905, filed August 22, 2022, U.S. Provisional Application No. 63 / 408,546, filed September 21, 2022, and U.S. Provisional Application No. 63 / 426,083, filed November 17, 2022.

[0002] (background) Gas streams at low partial pressures containing carbon dioxide (CO) and water vapor are produced in large-scale industrial processes, including energy production and the manufacture of construction materials such as cement and steel. For example, mixtures of CO, primarily nitrogen (i.e., flue gas), and water vapor are produced from steam methane reforming (SMR) to produce hydrogen and from the combustion of hydrocarbons for power generation. Mixtures of CO, water vapor, primarily nitrogen or air are produced from the manufacture of cement and steel and represent a significant fraction of all industrial CO emissions. Separation processes incorporating membranes can be used to separate permeable components, such as CO, from less permeable components, such as nitrogen, for subsequent sequestration. Generally, membrane separation can achieve high purity permeable components by combining multiple connected separation modules and the use of recycle streams. However, previous separation processes can incur high energy costs associated with significant compression and / or recycle of large volumes of gas streams, which are required for the separation and recovery of most of the permeable components from the gas stream. Summary of the Invention [Means for solving the problem]

[0003] (summary) The present disclosure addresses an unmet need for membrane separations that operate at relatively low pressures (i.e., ≦10 atm) and can separate and recover some or most of the permeable components (e.g., CO) using hydrophilic membranes. In some cases, the systems and methods described herein can maintain or increase permeability while maintaining separation selectivity up to higher stage cuts.

[0004] Useful membranes may include hydrophilic membranes that reversibly absorb and contain water, which may facilitate the permeation of a relatively water-soluble permeable component (e.g., CO2) from a feed stream that comprises humidity relative to a less permeable component (e.g., N2). Some hydrophilic membranes may also incorporate functional groups that reversibly interact with the permeable component in the presence of water, increasing its solubility and permeation. For example, the reversible interaction of CO2 with (e.g., amine-based) functional groups may improve the separation selectivity (separation efficiency) of the hydrophilic membrane under certain operating conditions. Some such membranes may be referred to herein as "transport-facilitating membranes."

[0005] The inventors have recognized that a disadvantage of using hydrophilic membranes is that water vapor in the wet feed stream is highly permeable and may be more permeable than the permeable component. High water vapor flux at high stage cuts can reduce the water content within the hydrophilic membrane, decreasing the permeability of the permeable component and thereby reducing separation selectivity.

[0006] As described herein, the aforementioned problems are solved by using a gaseous sweep stream comprising water vapor (e.g., having a similar or higher water vapor pressure than the wet feed stream) to reduce water vapor flux and help maintain a higher water content within the hydrophilic membrane. Heat transfer from the incoming gas stream or wet feed stream can be used to maintain the water temperature and corresponding partial pressure of water vapor in the sweep stream. The wet feed stream from the incoming gas stream from the industrial process is at a high temperature or can be made hotter through economical amounts of compression. The hydrophilic membrane can be operated more efficiently at an appropriate temperature and corresponding water vapor pressure. The water vapor may then be removed by several techniques, including compression knockout, condensation, drying, or a combination of these techniques.

[0007] Thus, in one embodiment, a system for separation of an input gas stream is provided, the system comprising: a sweep module comprising water; a heat transfer module configured to heat water in the sweep module and produce a sweep stream comprising water vapor, the water being heated using heat derived from or a stream derived therefrom; and a membrane separation module comprising a hydrophilic membrane partitioning the feed side from the permeate side; Equipped with The membrane separation module is receiving a wet feed stream on the feed side, the wet feed stream comprising a gas that is permeable through the hydrophilic membrane and a gas that is substantially impermeable through the hydrophilic membrane; receiving a sweep stream on the permeate side; passing a permeate gas through the hydrophilic membrane from the feed side to the permeate side, thereby combining the permeate gas with the sweep stream; configured to: The system is configured to produce a distillate stream exiting the feed side and depleted in permeate gas relative to the amount of permeate gas in the feed stream.

[0008] In some embodiments of the aforementioned systems, the wet feed stream is derived from the input gas stream.

[0009] In other embodiments of the above-described systems, the permeable gas in the wet feed stream enters the system along with the inlet gas stream.

[0010] In more embodiments of the aforementioned systems, the inlet gas stream is treated to produce a wet feed stream.

[0011] In other embodiments of the aforementioned systems, the sweep stream further comprises a portion of the distillate stream.

[0012] In a further embodiment of the aforementioned system, the sweep flow further comprises a portion of the permeable gas passing through the hydrophilic membrane.

[0013] In more embodiments of the above-described systems, the wet feed and sweep streams flow countercurrently within the membrane separation module.

[0014] In yet another embodiment of the above system, the permeate side has a vacuum pressure.

[0015] In different embodiments of the aforementioned systems, the sweep flow comprises greater than 99% water vapor.

[0016] In a further embodiment of the aforementioned system, the system further comprises a compressor or blower configured to increase the pressure of the incoming gas stream or the wet feed stream.

[0017] In other embodiments of the above system, the wet feed stream has a temperature between 60°C and 180°C.

[0018] In yet another embodiment of the aforementioned system, the permeable gas is CO 2 , an olefin, or oxygen.

[0019] In other embodiments of the aforementioned system, the substantially impermeable gas is N2 or paraffin.

[0020] In a more exemplary embodiment of the aforementioned system, the hydrophilic membrane comprises a polymeric material that incorporates functional groups that reversibly interact with the permeable gas.

[0021] In certain other embodiments of the aforementioned system, the functional group comprises a silver cation, which reversibly interacts with the olefin.

[0022] In other embodiments of the aforementioned system, the functional groups comprise imidazole-based or amine-based functional groups that reversibly interact with CO2.

[0023] In still more embodiments of the aforementioned systems, the system comprises multiple membrane separation steps.

[0024] In other embodiments of the aforementioned systems, the system comprises multiple membrane separation stages.

[0025] In some embodiments of the aforementioned systems, the sweep module and the heat transfer module are integrated within a vessel or enclosure.

[0026] In more embodiments of the aforementioned systems, the sweep module and the heat transfer module are connected through a conduit.

[0027] In a related embodiment, a method for separation of an input gas stream is provided, the method comprising: using heat from the inlet gas stream or a stream derived therefrom to heat water in the sweep module to produce a sweep stream comprising water vapor; providing a membrane separation module comprising a hydrophilic membrane partitioning a feed side from a permeate side; delivering a wet feed stream to the feed side, the wet feed stream comprising a gas that is permeable through the hydrophilic membrane and a gas that is substantially impermeable through the hydrophilic membrane; delivering a sweep stream to the permeate side; passing a permeate gas through the hydrophilic membrane from the feed side to the permeate side, thereby combining the permeate gas with the sweep stream; producing a fraction stream exiting the feed side and depleted in permeate gas relative to the amount of permeate gas in the feed stream; Includes.

[0028] In some embodiments of the method, the wet feed stream is derived from the input gas stream.

[0029] In another embodiment of the foregoing method, the permeable gas in a wet feed stream enters the system along with the inlet gas stream.

[0030] In more embodiments of the foregoing methods, the inlet gas stream is treated to produce a wet feed stream.

[0031] In yet another embodiment of the foregoing method, the sweep stream further comprises a portion of the distillate stream.

[0032] In yet another embodiment of the foregoing method, the sweep stream further comprises a portion of the permeable gas passing through the hydrophilic membrane.

[0033] In another alternative embodiment of the above method, the wet feed and sweep streams flow countercurrently within the membrane separation module.

[0034] In a further embodiment of the foregoing method, the permeate side has a vacuum pressure.

[0035] In another embodiment of the above method, the sweep stream comprises greater than 99% water vapor.

[0036] In other embodiments of the foregoing methods, the system further comprises a compressor or blower configured to increase the pressure of the incoming gas stream or the wet feed stream.

[0037] In yet further embodiments of the foregoing method, the wet feed stream has a temperature of 60° C. to 180° C.

[0038] In other embodiments of the foregoing method, the permeable gas is CO2, an olefin, or oxygen.

[0039] In some different embodiments of the aforementioned method, the substantially impermeable gas is N2 or paraffin.

[0040] In yet another embodiment of the foregoing method, the hydrophilic membrane comprises a polymeric material that incorporates functional groups that reversibly interact with the permeable gas.

[0041] In a different embodiment of the aforementioned method, the functional group comprises a silver cation, which reversibly interacts with the olefin.

[0042] In some specific embodiments of the aforementioned methods, the functional groups comprise imidazole-based or amine-based functional groups that reversibly interact with CO 2 .

[0043] In a further embodiment of the aforementioned method, the system comprises multiple membrane separation steps.

[0044] In certain other embodiments of the foregoing methods, the system comprises multiple membrane separation stages.

[0045] In yet another embodiment of the aforementioned method, the sweep module and the heat transfer module are integrated within a vessel or enclosure.

[0046] In more embodiments of the foregoing method, the sweep module and the heat transfer module are connected through a conduit.

[0047] This summary of the present invention introduces some of the aspects and embodiments of the present invention and is not intended to be limiting. As used herein, an aspect is a defining characteristic of the invention as recited in an independent claim and further disclosed in the detailed description. An embodiment may be considered a variation or one implementation of an aspect as recited in a dependent claim and further disclosed in the detailed description. Certain exemplary embodiments are described herein merely for the purpose of illustrating the invention and should not be construed as limiting the scope of the invention. Alternative embodiments, including certain modifications, combinations, and improvements of the described embodiments, will occur to those skilled in the art, and all such alternative embodiments are within the scope of the present invention.

[0048] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus comprising a list of elements is not necessarily limited to only those elements and may include other elements not expressly listed or inherent in such process, method, article, or apparatus. In addition, the use of "a" or "an" is employed to describe elements and components described herein. This is done merely for convenience and for the general sense of the scope of the invention. The description should be read to include one or at least one, i.e., the singular also includes the plural unless it is clear that it is meant otherwise. [Brief explanation of the drawings]

[0049] [Figure 1] FIG. 1 shows an example of an integrated membrane separation unit (1) consistent with the present disclosure, comprising connected modules including a membrane module (2) comprising a hydrophilic membrane, a heat transfer module (4), and a sweep module (3) comprising water and water vapor therefrom.

[0050] [Figure 2a] FIG. 2a shows an example of an integrated membrane separation unit (1) consistent with one or more embodiments of the present disclosure, further comprising a compressor or blower (11), an inlet gas stream (10), and an associated flow control module (15) that can control the vacuum pressure upstream of the permeate side of the membrane module (2).

[0051] [Figure 2b] FIG. 2b shows an example of an integrated membrane separation unit (1) consistent with one or more embodiments of the present disclosure, further comprising a portion control module (13) that can deliver a portion (7b) of the fraction stream (7) to the sweep module (3).

[0052] [Figure 3a] FIG. 3 a shows an example of an integrated membrane separation unit (1) consistent with one or more embodiments of the present disclosure, including a second separation module (14) that can increase the concentration of permeable components in the product stream (8) as part of a two-stage separation process.

[0053] [Figure 3b] FIG. 3b shows an example of an integrated membrane separation unit (1) consistent with one or more embodiments of the present disclosure, further including passing the wet feed stream (5) through a humidifier (3a) to increase the level of humidity as part of a two-stage separation process.

[0054] [Figure 4a] FIG. 4a shows an example of an integrated membrane separation unit (1) consistent with one or more embodiments of the present disclosure, further comprising a second separation module (16) that, as part of a two-step two-stage separation process, may additionally increase the recovery of permeable components compared to the two-stage separation process embodied in FIGS. 3a and 3b.

[0055] [Figure 4b]FIG. 4b shows an example of an integrated membrane separation unit (1) consistent with one or more embodiments of the present disclosure that, as part of a two-step, two-stage separation process, additionally includes passing a portion (5a) of the humidified feed stream (5) through a humidifier (3a) to increase the level of humidity, the humidifier (3a) including an additional heat transfer module (4b) to transfer heat from the humidified feed stream (5) and maintain the temperature of the water in the humidifier (3a).

[0056] [Figure 5] FIG. 5 shows an example of the systems and methods described herein in which a slipstream is taken from the permeate stream, goes through a water saturation step, and is recycled back into the permeate side of the membrane.

[0057] [Figure 6] FIG. 6 shows examples of the operation of the systems and methods described herein, with Example 1 demonstrating significantly increased permeability (top) and CO2 / N2 selectivity (bottom) maintained up to higher stage cuts for hydrophilic membranes using integrated membrane separation and a sweep flow with water vapor.

[0058] [Figure 7] FIG. 7 shows an example of the operation of the systems and methods described herein, where Example 2 shows that using an integrated separation unit in conjunction with a hydrophilic membrane, higher CO permeability (top) was achieved at a lower pressure ratio of 7, with fraction compositions below 2% achieved at a higher pressure ratio of 14 with a high stage cut, representing greater than 90% recovery of the permeable components (bottom).

[0059] [Figure 8] FIG. 8 shows an example of the operation of the systems and methods described herein, where Example 3 shows CO permeability (top) significantly increased with stage cut using a hydrophilic membrane comprising a fluorinated ionomer, and low fluctuation CO / N selectivity (bottom) extended to higher stage cuts using an integrated membrane separation unit and a sweep stream comprising water vapor.

[0060] [Figure 9] FIG. 9 shows an example of the operation of the systems and methods described herein, where Example 4 shows that using a non-hydrophilic membrane in an integrated membrane separation unit, an increase in permeability (top) of up to 17% was observed at the highest stage cut, while the CO / N selectivity (bottom) dropped by 20%. DETAILED DESCRIPTION OF THE INVENTION

[0061] (Detailed explanation) The present disclosure uses an integrated membrane separation unit comprising modules including a membrane separation module comprising a hydrophilic membrane, a heat transfer module, and a sweep module comprising water and water vapor derived therefrom. The membrane separation module has a feed side and a permeate side and is configured to receive a portion or substantially all (e.g., 100%) of a wet feed stream comprising an inlet gas stream on the feed side, the feed side comprising a concentration of a permeate component in the gas mixture. The membrane separation module is also configured to receive a sweep stream comprising water vapor on the permeate side. The hydrophilic membrane separates the feed side from the permeate side and is configured to separate a portion or all of the wet feed stream into a fraction stream exiting the feed side having a lower concentration of the permeate component and a permeate stream on the permeate side having a higher concentration of the permeate component. The permeate stream is combined with the sweep stream to form a combined stream exiting the permeate side. The sweep module is configured to supply the sweep stream comprising water vapor to the permeate side of the membrane module. The heat transfer module is configured to pass an inlet gas stream or a wet feed stream and maintain the temperature of the water through heat transfer from the inlet gas stream or the wet feed stream to the water. Thus, the partial pressure of water vapor in the sweep stream can advantageously be high (i.e., ≧0.2 atm) and, in certain embodiments, can be maintained without additional energy input using an integrated membrane separation unit.

[0062] In some embodiments, the membrane separation module may be configured to receive a sweep stream countercurrently (i.e., oppositely) to the feed stream. In some embodiments, the integrated membrane separation unit may be configured so that the partial pressure of water vapor in the sweep stream exceeds the pressure on the permeate side of the membrane module, and the sweep stream may be greater than 99% water vapor, or may consist essentially of steam. In some embodiments, the integrated membrane separation unit may be configured to maintain a vacuum pressure on the permeate side of the membrane separation module. In some embodiments, the integrated membrane separation unit may be configured to deliver a portion of the distillate stream exiting the feed side of the membrane separation module to the sweep module. A portion can be combined with the water vapor in the sweep module to increase the flow rate of the sweep stream. In some embodiments, the integrated membrane separation unit may include a compressor or blower configured to increase the pressure of the inlet gas stream with a corresponding increase in temperature through adiabatic compression. In some embodiments, the integrated membrane separation unit may be part of a larger separation process comprising multiple separation modules, including two-stage and two-step two-stage separation processes. Therein, the combined stream may be further processed to increase the concentration of the permeable component, remove water vapor, or be recycled to other separation modules within a larger separation process. In some embodiments, the distillate stream may be further processed, recycled, or removed from the separation process.

[0063] Various membrane separation terms are used herein. As used herein, a "membrane separation module" is a physical enclosure incorporating membranes configured therein that physically separates the module into two sections, i.e., a feed side and a permeate side. The membrane separation module and the membranes therein can be configured so that a pressure differential can be maintained between the feed side and the permeate side. As used herein, a "pressure ratio" is the ratio of the pressure on the feed side to the pressure on the permeate side. Additionally, a pressure less than ambient air pressure (i.e., < about 1 atm) can be referred to as a "vacuum pressure." For example, a feed stream flowing through a gas mixture and comprising a permeate component typically enters the feed side of a membrane separation module at a pressure above ambient air pressure. The "permeate component" selectively permeates through and across the membrane, forming a permeate stream on the permeate side of the membrane in the membrane separation module that is at a lower pressure (e.g., vacuum pressure) relative to the pressure of the feed stream but contains a higher concentration of the permeate component. The distillate stream may contain a lower concentration or partial pressure of the permeable component and a higher concentration of the less permeable component. The distillate stream may exit the feed side of the separation module at a pressure lower than the pressure of the feed stream.

[0064] As used herein, "stage cut" is the ratio of the permeate stream to the feed stream as a molar or volume fraction, which can be reported as a percentage. Useful stage cuts can be 10% to 60% or 20 to 40%. The permeability of the permeable component is normalized by the partial pressure difference between the feed and permeate sides and is expressed in Gas Permeability Units (GPU, 10 -6 cm 3 (STP)cm -2 s -2 cmHg -1) is the corresponding flux across the membrane, which can be quantified by the ratio of permeability to the less permeable component. A permeability ratio greater than 1 (defined by the permeability of the permeable component relative to the less permeable component) is a measure of separation selectivity and an indication of the efficiency with which the membrane can selectively permeate and separate the permeable component from the less permeable component. Useful membranes can have a separation selectivity for a permeable component, such as carbon dioxide, relative to a less permeable component, such as nitrogen, of at least 5, at least 20, or at least 40. Separation selectivity can be observed for hydrophilic membranes under ideal conditions (i.e., pure gas measurement at the limit of zero pressure ratio or zero stage cut).

[0065] Useful membranes may include hydrophilic membranes that reversibly absorb and retain water, which can promote the permeation of relatively water-soluble permeable components from a humid feed stream relative to less permeable components. Some hydrophilic membranes may also incorporate functional groups that reversibly interact with permeable components in the presence of water, increasing their solubility and permeation. For example, the reversible interaction of CO with amine-based functional groups, in some cases at temperatures between 60°C and 100°C, can improve the separation selectivity (separation efficiency) of hydrophilic membranes under certain operating conditions. Hydrophilic membranes may therefore be economically attractive for large-scale industrial separations and the capture of CO at relatively low pressures (e.g., ≦10 atm). However, significantly reduced permeability and separation selectivity at the high cutoffs required for the recovery of most permeable components can offset the advantages of hydrophilic membranes. For example, U.S. Patent Application No. 17 / 276,639, incorporated herein by reference in its entirety, discloses delivering a liquid water sweep stream at up to 60° C. to the permeate side of a pressure vessel. The liquid water sweep stream was used to increase the water vapor pressure and wet the hydrophilic membrane therein for improved permeation and selectivity performance at high pressures and stage cuts.

[0066] As used herein, a "system" can include an integrated separation module. As used herein, the term "substantially impermeable" means that components do not substantially permeate through the membrane, except, for example, through imperfections in the membrane. In some cases, the rate of permeation of a substantially impermeable gas is at least about 5, at least about 10, at least about 50, at least about 100, at least about 500, at least about 1,000, or at least about 10,000 times lower than the rate of permeation of a permeable gas through the membrane.

[0067] The embodiment of the present disclosure shown in FIG. 1 depicts components of an integrated membrane separation unit (1), which may be a single-stage membrane separation. FIGS. 2a-4b depict more complex embodiments comprising an integrated membrane separation unit (1) that may be connected to additional separation modules. In some embodiments, the integrated membrane separation unit (1) comprises at least three connected modules, including a membrane separation module (2) comprising a hydrophilic membrane, a sweep module (3) comprising water and water vapor, and a heat transfer module (4). The membrane separation module (2) may have a feed side (2a) and a permeate side (2b) and may be configured to receive 100% (i.e., FIGS. 1-3b) or a portion (i.e., 5a in FIGS. 4a and 4b) of the wet feed stream (5). The wet feed stream may comprise an inlet gas stream (10) comprising a concentration of a permeable component in the gas mixture on the feed side (2a). The membrane module can be configured to receive a sweep stream (9) comprising water vapor on the permeate side (2b). The design of the membrane separation module (2) and the form factor of the membranes configured therein can include flat sheet membranes, spiral wound flat sheet membranes, or hollow fiber membranes.

[0068] The inlet gas stream (10) may contain humidity in the gas mixture in addition to a concentration of permeable components, such as carbon dioxide (CO). In some embodiments, humidity may be added to the inlet gas stream (10) as needed to form a moist feed stream (5). Humidity may be added using a humidifier containing water and steam, and may be added before or after the heat transfer module (4) and before the membrane separation module (2). In some embodiments (e.g., FIGS. 2a, 2b, 3a, and 4a), the inlet gas stream (10) may be from an industrial process. For example, the inlet gas stream (10) may contain primarily about 20% to about 24% CO and steam in nitrogen and may result from the production of hydrogen, such as from steam methane reforming (SMR). Alternatively, the inlet gas stream (10) may be a by-product of cement or steel manufacturing and may contain primarily up to about 25% CO and steam in nitrogen. The inlet gas stream (10) may also be pre- or post-combustion flue gas from the combustion of hydrocarbons, such as for power generation, and may contain up to about 15% CO and water vapor, primarily in nitrogen, with some residual oxygen. In some embodiments, the inlet gas stream (10) may have a pressure above ambient air pressure and a temperature of at least 60°C. The pressure of the inlet gas stream (10) may be increased using a compressor or blower (11), as shown in Figures 2a-4b. For example, the pressure may be increased up to about 10 atm, with a corresponding increase in temperature resulting from adiabatic compression from 60°C to about 180°C. The pressure and temperature may be determined, at least in part, by the desired performance of the hydrophilic membrane in the integrated membrane separation unit (1) and / or the performance and overall economics of the separation process.

[0069] The hydrophilic membrane in the membrane separation module (2) separates the feed side (2a) from the permeate side (2b) and can be configured to separate a portion (i.e., 5a in FIGS. 4a and 4b) or 100% (e.g., FIGS. 1-3b) of the wet feed stream (5) into a distillate stream (7) exiting the feed side (2a) and having a lower concentration of permeable components, and a permeate stream in the permeate side (2b) having a higher concentration of permeable components, which is combined with the sweep stream (9) in the permeate side (2b) to form a combined stream (6) exiting the permeate side (2b). Water vapor in the combined stream (6) may subsequently be removed by techniques including compression knockout, condensation, drying, or a combination of these techniques. In some cases, the combined stream (6) may be further processed in a larger two-stage separation process to increase the concentration of the permeable components, as shown in Figures 3a and 3b, or recycled to the front of an even larger two-step two-stage separation process, as shown in Figures 4a and 4b.

[0070] The sweep module (3) can be configured to supply a sweep stream (9), comprising water vapor, to the permeate side (2b) of the membrane separation module (2). In some embodiments, the membrane separation module (2) can be configured to receive the sweep stream (9) in a countercurrent (i.e., opposite) direction to the wet feed stream (5), which can further improve separation efficiency. Water in or from the sweep module (3) can be thermally contacted with the heat transfer module (4). The inlet gas stream (10) or the wet feed stream (5) can pass through the heat transfer module (4), where heat is transferred from the inlet gas stream (10) or the wet feed stream (5) to water from or in the sweep module (3) and to water vapor formed from the water. The heat transfer module (4) can be integrated into a portion of the sweep module (3), as shown in Figures 1-4b. In some cases, the heat transfer module (4) may be separate from the sweep module (3), and the water therein may be connected to and in thermal contact with the heat transfer module (4) through a conduit pipe or other means. The heat transfer module (4) may be configured to maintain the temperature of the water as it evaporates to form water vapor and the temperature of the sweep stream (9) comprising the water vapor within the sweep module (3). Water may be replenished periodically as needed. Additional water is added to the sweep module (3) as it is consumed.

[0071] In the embodiment shown in Figures 2a-4b, the integrated membrane separation unit (1) can be configured to maintain a vacuum pressure on the permeate side (2b) of the membrane module (2). The vacuum pressure can be any pressure below ambient air pressure, and the integrated membrane separation unit (1) can include an integrated flow control module (15) that can control the vacuum pressure upstream of the permeate side (2b) and increase the downstream pressure of the combined stream (6). Thus, the integrated flow control module (15) can include a vacuum pump with a compressor and / or a vacuum pump (e.g., a diaphragm pump) that also has compression capabilities. A vacuum pressure of 0.14 to 0.2 psia can result in a suitable pressure ratio of 5 to 20 for the wet feed stream (5) or portion (5a) relative to the combined stream (6) and the performance of the membrane separation unit (1). In some embodiments, the temperature of the water may be high enough so that the partial pressure of water vapor in the sweep stream (9) exceeds the total pressure on the permeate side of the membrane separation module (2), and the sweep stream (9) may be greater than 99% water vapor, or consist essentially of steam.

[0072] In the embodiment shown in Figures 2b-4b, the integrated membrane separation unit (1) may be configured to deliver a portion (7b) of the distillate stream (7) exiting the feed side (2a) to the sweep module (3). The portion (7b) may be 1% to 50% of the wet feed stream (5) or its portion (5a) (e.g., 1% to 25%) so as not to substantially dilute the permeable component in the combined stream (6) with the low-permeable component. The portion (7b) may be pressure-reduced and delivered to the sweep module (3) through the use of a portion control module (13), which may include a bleed valve or pressure regulator. The portion (7b) may be combined with steam in the sweep module (3) to form a sweep stream (9) comprising steam, further increasing the flow rate and recovery of the permeable component.

[0073] In some embodiments (e.g., as shown in Figures 3a and 3b), membrane separation unit (1) may be a component of a larger two-stage separation process that includes an additional separation module (14), which may serve to increase the concentration of permeable components in product stream (8). The additional separation module (14) is configured to separate combined stream (6) into product stream (8) and a second fraction stream (12) that may be recycled and combined with wet feed stream (5) prior to receiving wet feed stream (5) into membrane module (2). In some embodiments (e.g., Figure 3b), second fraction stream (12) may be combined with input gas stream (10) and then passed through a humidifier (3a) comprising water and steam to add or increase the humidity level and form wet feed stream (5) prior to receiving it into membrane separation module (2). The additional separation module (14) can include a membrane that is selectively permeable to the permeable components in the combined stream (6). In some embodiments, the additional separation module (14) can include other CO separation processes, including gas-liquid contactors, which can incorporate amine scrubbing.

[0074] In some embodiments (e.g., as shown in Figures 4a and 4b), the integrated membrane separation unit (1) can be part of a larger two-step, two-stage separation process. This can further increase the recovery of the permeate component relative to the two-stage separation process shown in Figures 3a and 3b. The two-step, two-stage separation process includes a second membrane separation module (16) incorporating a membrane that selectively allows the permeate component to pass through. The second membrane separation module (16) is upstream of the membrane separation module (2) and is configured to receive substantially all of the wet feed stream (5) and separate it into a third fraction stream and a second permeate stream (5b). Thus, the membrane module (2) in the integrated membrane separation unit (1) receives a portion (5a) of the wet feed stream (5) as the third fraction stream. Portion (5a) may also comprise humidity. In some embodiments (e.g., FIG. 4b), the third fraction stream may be passed through a humidifier (3a) comprising water and water vapor to add humidity or increase the humidity level in portion (5a). Humidifier (3a) may also comprise an additional heat transfer module (4b) to transfer heat from the inlet gas stream (10) or the wet feed stream (5) to the water and maintain the temperature of the water within humidifier (3a). Portion (5a) may be 40% to 90% or 60% to 80% of the wet feed stream (5), corresponding to a stage cut of 60% to 10% or 40% to 20%, respectively. An additional separation module (14) may be configured to receive second permeate stream (5b) and separate it into product stream (8) and second fraction stream (12). Therein, both the second fraction stream (12) and the combined stream (6) may be combined with the inlet gas stream (10) or the wet feed stream (5) prior to the wet feed stream (5) being received into the second membrane separation module (16).

[0075] In some cases, the systems and methods described herein can use a partial permeate sweep configuration. As shown in FIG. 5, for a single stage having a feed stream 20 and producing a fraction 21, a slipstream 22 is taken from the permeate stream 23 and recycled through a water saturation step 24 back into the permeate side of the membrane 25. Like the fraction sweep embodiment, this can be operated with a permeate vacuum, which aids in humidification. Here, the sweep stream (i.e., under low pressure and high temperature) can retain a significant amount of water in the gas phase. When recycling the fraction, the CO2 concentration is very low, leading to increased driving force. However, to achieve effective humidification, the mainstream stream can be comparable in size to the permeate stream and thus dilute it. This configuration, illustrated in FIG. 5, is an option for correcting this problem, as the sweep stream can have a higher CO2 concentration (e.g., the same dry basis concentration as the permeate stream at steady state).

[0076] Separation processes incorporating the integrated membrane separation unit (1) may be carried out using any hydrophilic membrane in the membrane separation module (2) that is capable of reversibly absorbing and retaining water, including liquid water, and selectively transmitting permeable components, including CO2, olefins, or oxygen, from a gas mixture. The membrane may be a composite membrane comprising or consisting of multiple layers, including a hydrophilic gas separation layer, a gutter layer, and a porous support. The porous support may have form factors including a flat sheet, a spirally wound flat sheet, or a hollow fiber. Composite membranes on hollow fiber porous supports may be more easily configured in the membrane separation module (2) for a countercurrent mode of operation, with the feed and permeate gases flowing in opposite directions along the length of the hollow fiber. Suitable materials for the hollow fiber include polyamide, polysulfone, polyethersulfone, polyvinylidene fluoride (PVDF), and polyetheretherketone (PEEK).

[0077] The gas separation layer can incorporate a hydrophilic polymeric material (e.g., a hydrogel) that can be formed into a thin film. Examples of hydrophilic polymeric materials that can selectively permeate CO2 or oxygen from a gas mixture include polyvinyl alcohol, polyethylene oxide, polypropylene oxide, and polyimide. Ionomers are hydrophilic polymeric materials that contain ionic functional groups and can be formed into a thin film. Fluorinated ionomers can be useful as hydrophilic polymeric materials in the gas separation layer of composite membranes for CO2 separation, such as those disclosed in PCT Application No. US2019 / 024517 (incorporated herein by reference in its entirety). Composite membranes incorporating fluorinated ionomers can have CO2 permeabilities exceeding 1,000 GPU and nitrogen selectivities of at least 40. Examples of fluorinated ionomers include Nafion® (Chemours, Wilmington DE) and Aquivion® (Solvay, Houston TX). Fluorinated (and non-fluorinated) ionomers with silver cations may also be used for the separation of olefin-paraffin streams in refinery processes (the permeable component is the olefin) or for the separation of oxygen from nitrogen.

[0078] The gas separation layer may comprise a hydrophilic polymeric material containing functional groups that reversibly interact with the permeable component and increase its permeability. The functional groups can comprise silver cations, such as silver sulfonate, for the separation of olefin-paraffin streams. In some cases, the functional groups can be amine- or imidazole-based for the separation of CO2. The reversible interaction of CO2 with the amine- or imidazole-based functional groups in the presence of water (e.g., at temperatures between 60°C and 100°C) can increase CO2 permeability and gas separation selectivity. For example, hydrophilic membranes incorporating amine-containing polymeric materials that may be suitable for membrane module (2) are described in U.S. Pat. No. 10,835,847 (incorporated herein by reference). Other suitable hydrophilic polymeric materials that may incorporate amine-based functional groups include, for example, homopolymers and copolymers comprising "vinylamine," "allylamine," or "ethyleneimine" repeating units. Some of these polymeric materials are commercially available or may be prepared through the homopolymerization and copolymerization of related monomers, such as N-vinylformamide, or precursor repeat units with amine-based functional groups. Hydrophilic polymeric materials may also contain amine- or imidazole-based functional groups that also carry a positive charge, such as quaternary ammonium or imidazolium groups, respectively. Examples of the latter include poly(imidazole-imidazolium)-based polymers, which may include methylated polybenzimidazole polymers.

[0079] (Example) Example 1: Separation of CO2 using an integrated membrane separation unit and hydrophilic membrane with or without a sweep stream with water vapor. An integrated membrane separation unit was assembled using a four-port membrane separation module with an L / D ratio of approximately 45, configured for countercurrent operation with inlets for a feed stream with humidity, a sweep stream with water vapor, and outlets for the distillate stream and the combined or permeate stream (no sweep). The hydrophilic membrane configured within the membrane separation module was a multilayer composite membrane (100 cm) on hollow fiber with a gas separation layer (approximately 0.3 μm) from a poly(imidazole-imidazolium)-based polymer and associated hydroxide counteranion. 2 Using humidified pure gas, the membrane had a CO2 permeability of approximately 600 GPU and a CO2 / N2 selectivity of 110 at the limit of zero pressure ratio or zero stage cutoff.

[0080] The feed stream is a 12% CO2 in nitrogen mixture at 100-500 mL / min, using Nafion TM A first Perma Pure tube with liquid water on the shell side of the hollow tube. TM The sweep module and the sweep stream with water vapor were simulated by passing a portion of the distillate stream through a needle valve and then through a second PermaPure TM The humidifiers were simulated by branching the humidifier piping. The outlet of the first humidifier was connected to the feed inlet of the membrane separation module, while the outlet of the second humidifier was connected to the sweep inlet. Both the humidifiers and the membrane separation module were immersed in a 60°C water bath to simulate the transfer of heat from the heat transfer module and the feed stream to the water. A pressure ratio of 14 for the combined or permeate streams (0.2 atm) with the feed stream (2.8 atm) was maintained by adjusting the flow rate of the feed stream (without sweep stream) or a needle valve (with sweep stream) to vary the stage cut. Table 1 shows the operating parameters and performance of the integrated membrane separation unit. Figure 6 shows significantly increased permeability at higher stage cuts and maintained CO2 / N2 selectivity up to higher stage cuts using a sweep stream with water vapor. [Table 1]

[0081] Example 2: Separation of CO2 at varying pressure ratios using an integrated membrane separation unit and hydrophilic membrane with and without a sweep flow with water vapor. As described in Example 1, an integrated membrane separation unit with a membrane separation module therein comprises a multilayer composite membrane (100 cm) on hollow fiber having a gas separation layer (approximately 60 nm) from a poly(imidazole-imidazolium)-based polymer and associated hydroxide counteranion. 2 ). Using humidified pure gas, the membrane had a CO2 permeability of approximately 2,600 GPU and a CO2 / N2 selectivity of approximately 100 at the limit of zero pressure ratio or zero stage cut. A feed stream with humidity and a concentration of permeable components in the gas stream was simulated using a 20% CO2 in nitrogen mixture as described in Example 1. A sweep module, heat transfer module, and sweep stream with water vapor were also simulated as described. A pressure ratio of 7 or 14 for the combined feed stream (1.4 or 2.8 atm) or permeate stream (0.2 atm) was maintained using adjustment of the feed flow rate (without sweep) or needle valve (with sweep) to vary the stage cut. Table 2 shows the operating parameters and performance of the integrated membrane separation unit at two pressure ratios. Figure 7 shows a higher CO2 permeability at the lower pressure ratio of 7. However, fraction compositions that were less than 2% were achieved at higher pressure ratios of 14 at high stage cuts using sweep flow, representing greater than 90% recovery of the permeable components. [Table 2]

[0082] Example 3: Separation of CO2 using an integrated membrane separation unit and hydrophilic membrane incorporating a fluorinated ionomer with or without a sweep stream with water vapor. The integrated membrane separation unit and membrane separation module therein as described in Example 1 comprised a multilayer composite membrane (96 cm) on hollow fiber having a gas separation layer (approximately 0.11 μm) from a fluorinated ionomer containing sulfonic acid functional groups. 2 ). Using humidified pure gas, the membrane had a CO2 permeability of approximately 2,000 GPU and a CO2 / N2 selectivity of approximately 40 at the limit of zero pressure ratio or zero stage cut. The feed stream, with humidity and a concentration of permeate components in the gas stream, was simulated using a 20% CO2 in nitrogen mixture as described in Example 1. The sweep module, heat transfer module, and sweep stream with water vapor were also simulated as described. A pressure ratio of 7 for the feed stream (1.4 atm) and the combined or permeate stream (0.2 atm) was maintained using adjustment of the feed flow rate (without sweep) or needle valve (with sweep) to vary the stage cut. Table 3 shows the operating parameters and performance of an integrated membrane separation unit incorporating a fluorinated ionomer. FIG. 8 shows that using a sweep flow with water vapor, CO permeability appeared to increase linearly with stage cut, and low-variance CO / N selectivity appeared to extend to higher stage cuts. [Table 3]

[0083] Example 4: Comparative example using a non-hydrophilic membrane in an integrated membrane separation unit. The integrated membrane separation unit and the membrane separation module therein as described in Example 1 comprise a composite membrane (23 cm) on hollow fibers with a gas separation layer (approximately 1.5 μm) made of a non-hydrophilic polymer material. 2) was configured. Using pure gas, the membrane had a CO2 permeability of approximately 4,700 GPU and a CO2 / N2 selectivity of approximately 10 at the limit of zero pressure ratio or zero stage cut. A feed stream with humidity and a concentration of permeable components in the gas stream was simulated using a 20% CO2 in nitrogen mixture as described in Example 1. A sweep module, heat transfer module, and sweep stream with water vapor were also simulated as described. A pressure ratio of 7 for the feed stream (1.4 atm) and combined stream or permeate stream (0.2 atm) was maintained using adjustment of the feed stream flow rate (without sweep stream) or needle valve (with sweep stream) to vary the stage cut. Table 4 shows the operating parameters and performance of membranes incorporating non-hydrophilic polymer materials within an integrated membrane separation unit. Figure 9 shows that using a sweep stream resulted in a slight increase in permeability of up to 17% at the highest stage cut. However, the CO2 / N2 selectivity dropped by 20%. [Table 4]

Claims

1. A system for separating inflow gas flow, wherein the system is a. A sweeping module equipped with water, b. A heat transfer module configured to heat the water in the sweep module and produce a sweep flow containing steam, wherein the water is heated using heat derived from or a flow derived from the inflow gas flow, c. A membrane separation module equipped with a hydrophilic membrane that partitions the supply side from the permeate side. Equipped with, The aforementioned membrane separation module is i. Receiving a moist supply flow on the supply side, wherein the moist supply flow comprises a gas that is permeable through the hydrophilic membrane and a gas that is substantially impermeable through the hydrophilic membrane. ii. Receiving the sweep flow on the permeate side, iii. The permeable gas is passed through the hydrophilic membrane from the supply side to the permeate side, thereby combining the permeable gas and the sweep flow. It is configured to do the following: The system is configured to produce a fractional flow that exits from the supply side and is depleted in the permeable gas relative to the amount of permeable gas in the supply flow.

2. The aforementioned moist supply flow is derived from the inflow gas flow, The permeable gas in the moist supply flow enters the system together with the incoming gas flow and / or The system according to claim 1, wherein the incoming gas flow is treated to produce the moist feed flow or the sweep flow.

3. The system according to any one of claims 1 to 2, wherein the sweeping flow further comprises a portion of the distillation flow.

4. The system according to any one of claims 1 to 2, wherein the sweep flow further comprises a portion of the permeable gas passing through the hydrophilic membrane.

5. The system according to any one of claims 1 to 2, wherein the moist supply flow and the sweep flow flow in the reverse direction within the membrane separation module.

6. The system according to any one of claims 1 to 2, wherein the permeation side has a vacuum pressure.

7. The sweeping flow comprises more than 99% water vapor, according to any one of claims 1 to 2.

8. The system according to any one of claims 1 to 2, further comprising a compressor or blower configured to increase the pressure of the incoming gas flow or the moist supply flow.

9. The system according to any one of claims 1 to 2, wherein the moist supply flow has a temperature of 60°C to 180°C.

10. The system according to any one of claims 1 to 2, wherein the hydrophilic film comprises a polymer material incorporating functional groups that reversibly interact with the permeable gas.

11. The aforementioned functional group is CO ２ The system according to claim 10, comprising an imidazole-based functional group or an amine-based functional group that interacts reversibly with the same.

12. The system according to any one of claims 1 to 2, comprising a plurality of membrane separation steps or membrane separation stages.

13. A method for separating an inflowing gas flow, wherein the method is a. Using the heat from the incoming gas flow or the flow emanating therefrom, heat the water in the sweep module to produce a sweep flow containing steam, b. To provide a membrane separation module equipped with a hydrophilic membrane that partitions the supply side from the permeate side, c. A moist supply flow is supplied to the supply side, wherein the moist supply flow comprises a gas that is permeable through the hydrophilic membrane and a gas that is substantially impermeable through the hydrophilic membrane. d. Supplying the sweep flow to the permeate side, e. The permeable gas is passed through the hydrophilic membrane from the supply side to the permeate side, thereby combining the permeable gas and the sweep flow. f. To produce a fractional flow that exits from the supply side and is depleted in the permeable gas relative to the amount of permeable gas in the supply flow. Methods that include...

14. The method according to claim 13, wherein the sweep flow further comprises a portion of the distillation flow.

15. The method according to any one of claims 13 or 14, comprising a plurality of membrane separation steps or membrane separation stages.

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