Housing system for multiple membrane cartridges for gas separation

Abstract

A membrane system (1) for separating a feed gas stream (F) at low pressure into a retentate gas stream (R) and a permeate (P) stream, the system (1) comprising a housing (2) and a plurality of membrane cartridges (3) having a first end (3a) and an opposite second end (3b), wherein the housing (2) comprises a first intermediate wall (4) and a second intermediate wall (5) dividing an inner space of the housing (2) into a feed subspace (21), a retentate subspace (22) and a permeate subspace (23), wherein the membrane system (1) comprises in an outer wall of the housing (2) a feed gas stream inlet (11) fluidly connected to the feed subspace (21), a retentate gas stream outlet (12) fluidly connected to the retentate subspace (22), and a permeate gas stream outlet (13) fluidly connected to the permeate subspace (23); wherein each membrane cartridge (3) comprises a cartridge housing (30), a gas selective membrane, a feed inlet (31), a retentate outlet (32) and a permeate outlet (33), wherein each membrane cartridge (3) of the plurality of membrane cartridges (3) is releasably insertable into a mounted position between the first intermediate wall (4) and the second intermediate wall (5) such that the feed inlet (31) of each membrane cartridge (3) opens towards the feed subspace (21), the permeate outlet (33) of each membrane cartridge (3) opens towards the permeate subspace (22) and the retentate outlet (32) of each membrane cartridge (3) opens towards the retentate subspace (23), wherein the first end (3a) of each of the plurality of membrane cartridges (3) is arranged at the first intermediate wall (4) and the second end (3b) of each of the plurality of membrane cartridges (3) is arranged at the second intermediate wall (5); wherein the volume of the feed subspace (21) is at least one third of the total volume of the housing (2).

Description

[0001] Housing system for multiple membrane cartridges for gas separation

[0002] Technical Field

[0003] The invention relates to a membrane system for separating a feed gas stream at low pressure into a retentate gas stream and a permeate gas stream comprising a plurality of membrane cartridges.

[0004] Technical Background

[0005] Membrane technology is often used for gas separation of a feed gas stream into a retentate gas stream and a permeate gas stream. The gas selective membranes are installed in a membrane cartridge - often in cylindrical shape - provided with a feed stream inlet, a retentate stream outlet and a permeate stream outlet. Examples of membrane cartridges are described e.g. in US2017348643 and JP2003144859. Several such membrane cartridges are usually combined to a gas separation membrane system, wherein the individual inlets and outlets are connected to each other with a large amount of piping connections. An example is disclosed in US2018264412, US2007107596 and W02009082392. For large scale membrane systems (e.g. > 100 cartridges) the high amount of piping connections lead to a high trans-membrane pressure drop and, therefore, lower separation performance. The risk of leakage is also higher with multiple connections.

[0006] US10010832 proposes to use a container, e.g. standard shipping container, as a housing for membrane stacks in a housing to reduce the material and transportation cost. However, the proposed design is limited to membrane stacks, which have large footprint and low packing density. This design also results in demanding maintenance and membrane replacement.

[0007] US7790030 relates to a fluid separation via multiple membrane cartridges or modules disposed within a pressure vessel. The vessel defines small space for a permeate gas stream at each end of the multiple membrane cartridges. However, the proposed design is rather complex and results in demanding maintenance and membrane replacement.

[0008] US2006174762 describes high-pressure gas-separation membrane module assembly. The assembly includes a set of tubes, each containing gas-separation membranes, arranged within a housing. The housing contains tube sheets that divide the space within the housing into three separate, gas-tight spaces, with the tubes mounted in the central space. The housing is a steel pressure vessel with two ends and an elongated central section, adapted

[0009] P248937 to withstand the relatively high differential pressures that are used in this type of gas separation. The tubes may contain one or more membrane elements or cartridges.

[0010] Summary of the Invention

[0011] It is an objective of the invention to provide an energy efficient membrane system or membrane housing system for accommodating a large amount (at least 100 and up to several hundreds) of membrane cartridges in an easily replaceable manner.

[0012] At least one of the objectives of the present invention is achieved by a membrane (housing) system for separating a feed gas stream at low pressure (e.g. 1 to 1.5 bara) into a retentate gas stream and a permeate gas stream according to claim 1 and a process according to claim 14.

[0013] The membrane system comprises a housing and a plurality of membrane cartridges having a first end and an opposite second end. The housing comprises a first intermediate wall and a second intermediate wall dividing an inner space of the housing into a feed subspace, a retentate subspace and a permeate subspace. The membrane system further comprises in an outer wall of the housing a feed gas stream inlet fluidly connected to the feed subspace, a retentate gas stream outlet fluidly connected to the retentate subspace, and a permeate gas stream outlet fluidly connected to the permeate subspace. Each membrane cartridge comprises an outer wall, a gas selective membrane (arranged within the outer wall), a feed inlet, a retentate outlet and a permeate outlet. Each membrane cartridge of the plurality of membrane cartridges is releasably insertable into a mounted position between the first intermediate wall and the second intermediate wall such that the feed inlet of each membrane cartridge opens towards the feed subspace, the permeate outlet of each membrane cartridge opens towards the permeate subspace and the retentate stream outlet of each membrane cartridge opens towards the retentate subspace. The first end of each of the plurality of membrane cartridges is arranged at the first intermediate wall and the second end of each of the plurality of membrane cartridges is arranged at the second intermediate wall, such that the entire space between the first intermediate wall and the second intermediate wall may be used as subspace to collect a fluid. The volume of the feed subspace is at least one third of the volume of the housing.

[0014] Preferably, the retentate subspace is arranged between the first intermediate wall and the second intermediate wall.

[0015] Thus, the housing of the membrane system is separated by only two intermediate walls in subspaces for the different gas streams, wherein the retentate subspace may be arranged

[0016] P248937 between the feed subspace and the permeate subspace. In other words, the feed subspace may be formed by housing wall and first intermediate wall, the retentate subspace may be formed by the housing wall, the first intermediate wall and the second intermediate wall, and the permeate subspace may be formed by the second intermediate wall and the housing wall, or by a separate permeate housing forming at one side the second intermediate wall.

[0017] The large relative volume of the feed subspace allows an energy efficient gas separation at low pressure with a high mass flow rate. During operation the absolute pressure in the feed subspace is typically between 1 and 1.5 resulting in an overpressure below 500 mbar. The large volume of the feed subspace allows an efficient distribution of the feed gas to the feed inlets of all the membrane cartridges, which may amount to several hundreds.

[0018] Thus, the membrane housing may be a lightweight construction designed for low pressure applications and is particularly suitable for low pressure gas separation with low amounts of a desired gas to be separated from a feed gas stream. The amount desired gas in the feed gas stream may be as low as 5 to 20%.

[0019] The two intermediate walls also carry the releasably mounted membrane cartridges and no further supporting structure is necessary for the membrane cartridges.

[0020] The membrane cartridges are typically mounted in a sealing manner and held in place between the first intermediate wall and the second intermediate wall. Thus, the feed subspace is fluidly connected to the retentate subspace and the permeate subspace only by the plurality of membrane cartridges. Piping is only required to connect the membrane system with the feed gas stream inlet, the retentate gas stream outlet and the permeate gas stream outlet to the different gas streams. Several systems can be connected in series, in parallel or combinations thereof. The membrane cartridges in the membrane system are arranged in parallel manner and fed with feed gas from the feed subspace. Retentate gas and permeate gas of each membrane cartridge is collected in the retentate subspace and the permeate subspace, respectively, and the collected gases leave the membrane system through the retentate gas stream outlet and the permeate gas stream outlet, respectively. No piping is required or present for the individual membrane cartridges. Minimizing the number of piping connections enables a uniform feed composition and partial pressure along the system. It also simplifies the replacement of the cartridges and the obtaining of a gas tight system. In addition, the individual membrane cartridges can be easily replaced if necessary and the housing allows for higher packing densities of membrane cartridges. Furthermore, the membrane system facilitates the removal of condensate in that the

[0021] P248937 condensate may be collected in (e.g at the bottom of) in each subspace. Thus, the membrane system may comprise a drain or drain system for condensate in each subspace.

[0022] Further embodiments of the invention are set forth in the dependent claims.

[0023] In some embodiments the feed inlet may be arranged at a first end of the membrane cartridge, the permeate outlet may be arranged at a second end of the membrane cartridge and the retentate outlet may be arranged between the feed inlet and the permeate outlet, preferably near the permeate outlet. The membrane cartridges are then placed within the housing with the first end including the feed inlet in the feed subspace, and the second end including the permeate outlet in the permeate subspace. The retentate outlet is then arranged in the retentate subspace between the feed subspace and the permeate subspace.

[0024] In some embodiments the first intermediate wall may comprise a first cartridge opening for every membrane cartridge of the plurality of membrane cartridges. The second intermediate wall may comprise a second cartridge opening for every membrane cartridge of the plurality of membrane cartridges. The first and second openings may be arranged in a regularly spaced manner to optimize the total number of membrane cartridges within the membrane system.

[0025] In some embodiments the feed inlet of the membrane cartridge or the cartridge housing may extend over an upper surface of the first intermediate wall facing the feed subspace, and forms together with the housing and the first intermediate wall a condensate reservoir to collect condensate in the feed subspace. Thereby condensate, which may accumulate in the feed subspace, is prevented from entering the membrane cartridge. The feed subspace may be further provided with a system for draining the condensate from the reservoir. Such a condensate reservoir and condensate drainage system are particularly useful when feeding the membrane system with flue gas. Flue gas typically contains large amounts of water. In some embodiments an outer cylindrical wall of the cartridge may be arranged in the first cartridge opening of the first intermediate wall in a sealing manner. The permeate outlet of the membrane cartridge may be a tube, which may be pushed through the second opening of the second intermediate wall in a sealing manner. For sealing a first cartridge seal may be provided in the first cartridge opening and a first cartridge seal may be provided in the second cartridge opening or around the tube of the permeate outlet. The membrane cartridge may be held in place by mere gravitational force. The tube of the permeate outlet may be provided with a flange resting on the second intermediate wall inside the retentate subspace. The flange also ensures correct placement of the cartridge in axial direction. The

[0026] P248937 cartridge may be held in place by a slight clamping force of the first and second cartridge seals. No further attachment means are required.

[0027] In some embodiments of a cylindrical membrane cartridge, the feed inlet may be arranged at the first end of the membrane cartridge. The retentate outlet and the permeate outlet may be arranged at the second end of the membrane cartridge, the second end being opposite the first end. The permeate outlet may be defined by the tube having a smaller diameter than the cylindric outer wall of the cartridge. The tube may extend over the outer wall in axial direction. The retentate outlet may be arranged between the tube and the outer wall.

[0028] In some embodiments the membrane cartridge may be a cylindrical cartridge. The membrane cartridge may have lengths of 20 cm to 150 cm, preferably approx. 100 cm. The diameter of the cartridge may be 3 cm to 25 cm, preferably approx. 20 cm. Other shapes and size are possible as well. The membrane cartridge typically holds a spiral wound gas separation element.

[0029] In some embodiments the first cartridge opening and the corresponding second cartridge opening may be sealingly closed with a sealing element in case the membrane system is not used with a full capacity of membrane cartridges, i.e. some of the first cartridge opening and the corresponding second cartridge opening are empty. To facilitate the closing of first and second openings, dummy cartridges with closed in- and outlet and without membranes may be used.

[0030] In some embodiments the first cartridge opening may be larger than the second cartridge opening. The openings facilitate assembly and disassembly of the cartridge in that the cartridges can be slid through the openings into a mounted position. The first cartridge opening may correspond to the diameter of the outer wall of the cylindrical membrane cartridge. The second cartridge opening may correspond to the diameter of the tube of the permeate outlet of the cylindrical membrane cartridge, which diameter is smaller than the diameter of the outer wall of the cylindrical membrane cartridge. The outer wall of the membrane cartridge is spaced apart from the second intermediate wall to leave enough space for the retentate outlet between the outer wall of the membrane cartridge and the tube of the permeate outlet.

[0031] In some embodiments the tube of the permeate outlet is provided with the second cartridge seal in form of an O-ring to engage with the second cartridge opening in a sealing manner when sliding the cartridge into a mounted position. The first cartridge opening may be provided with the first cartridge seal to engage with the outer wall of the cartridge at the first end in a sealing manner when sliding the cartridge into a mounted position.

[0032] P248937 In some embodiments the first cartridge opening and / or the second cartridge opening may be provided with an adapter. The adapter may be used for differently sized cartridges and to provide a gas tight connection of the membrane cartridge with the first and / or second intermediate wall.

[0033] In some embodiments the housing may be a standard shipping container, also known as intermodal container, cargo container or ISO container. The shipping container may be a High Cube container (e.g. high-cube 40 ft container) with a height of 2.90 m. The first and second intermediate wall may be arranged in the shipping container and sealed towards the container wall. The housing may also be large preferably rectangular box preferably with a length of at least 3 m, width of at least 2 m, and a height of at least 2 m.

[0034] In some embodiments the first intermediate wall and the second intermediate wall may be arranged horizontally within the housing and the plurality of membrane cartridges are arranges vertically. Alternatively, the first intermediate wall and the second intermediate wall are arranged vertically within the housing and the plurality of membrane cartridges are arranges horizontally.

[0035] In some embodiments a distance between the first intermediate wall and the second intermediate wall may be smaller than the total length of the membrane cartridge. A distance in the feed subspace between the first intermediate wall and the wall of the housing may be larger than the total length of the membrane cartridge. In other words, a height of the feed subspace in a direction parallel to the direction for mounting the membrane cartridge is larger than the total length of the membrane cartridge to create enough space for placing or removing each membrane cartridge. For maintenance and removal of the releasably mounted cartridges from the housing, the cartridges may be lifted out of the first and second openings in an axial direction of the cartridge and then moved sideways, i.e. perpendicular to the axial direction. The housing may comprise a hatch or a door in a side wall of the housing for accessing the feed subspace.

[0036] The second intermediate wall is typically arranged at the second end of the membrane cartridge and may create a seal around the permeate outlet of the membrane cartridge. The first intermediate wall may be arranged near the first end of the membrane cartridge creating a seal towards an outer surface of the membrane cartridge. The first intermediate wall may also be arranged near a centre of the membrane cartridge. This may be useful to create more space between the first intermediate wall and the housing wall for placement or removal of the membrane cartridges.

[0037] P248937 When the first intermediate wall is arranged at the first end of the membrane cartridge it is possible to remove a single membrane cartridge of the plurality of membrane cartridges from the housing independent of its position.

[0038] In some embodiments the permeate subspace may be formed by gas tight inner housing whereof one side forms the second intermediate wall.

[0039] In some embodiments the housing is provided with a door in a side wall. The door may open to at least one of the subspaces for maintenance.

[0040] In some embodiments the membrane system may be provided with handling means or a handling device for automated cartridge replacement. The device may be installed in the feed subspace. The device may be adapted to place or remove several membrane cartridges at once, e.g. with a gripping arm or apparatus for several membrane cartridges.

[0041] The membrane system may be provided with a heating system to avoid condensation inside the housing. The housing may be provided with a heat insulation.

[0042] The membrane system may be used for any type of gas separation. A standard shipping container may be used to provide a housing for low pressure gas separation, whereas for high pressure gas separation a specially reinforced housing can be used.

[0043] A driving force for the gas stream through the membrane cartridge may be provided by applying a pressure difference between the feed subspace and the permeate subspace. E.g. by applying a higher pressure in the feed subspace or by applying a vacuum in the permeate subspace.

[0044] The invention further relates to a process for separating a feed gas stream into a retentate gas stream and a permeate stream using a membrane system as described above. The method comprises the steps of: (a.) feeding a feed gas stream to the feed gas stream inlet of the membrane system; (b.) recovering a separated permeate gas stream from the permeate gas stream outlet.

[0045] In general, the membrane system may be used like individual membrane cartridges or modules with the difference that a large number of membrane cartridges can be fed with feed gas by a single feed gas stream inlet and the feed subspace. The retentate gas stream and the permeate gas stream are recovered through the retentate gas stream outlet from the retentate subspace and the permeate gas stream outlet from the permeate subspace, respectively.

[0046] The membrane system may be used for a variety of gas sources and separated gases. Examples include:

[0047] P248937 a) The feed gas may be flare gas and the membrane cartridges are adapted to separate olefin from the flare gas. b) The membrane system may be used for separating CO2 from feed gas e.g. flue gas or other gas sources. Accordingly, the membrane cartridges are adapted to separate CO2 from the feed gas. c) The membrane system may be used for hydrogen purification by separating hydrogen and methane.

[0048] Thus, in some embodiments the permeate gas stream may be selected from the group of olefins separated from flare gas as feed gas stream, CO2 separated from flue gas as feed gas stream or hydrogen separated from a methane feed gas stream.

[0049] Brief Explanation of the Figures

[0050] The invention is described in greater detail below with reference to embodiments that are illustrated in the figures. The figures show:

[0051] Fig. 1 a schematic representation of a membrane system with three subspaces;

[0052] Fig. 2 a schematic representation of a membrane system showing a placement of a cartridge;

[0053] Fig. 3 a schematic representation of a membrane system with a lower first intermediate wall;

[0054] Fig. 4 a schematic representation of a membrane system with a vacuum chamber;

[0055] Fig. 5 a schematic drawing of a container with a plurality of membrane cartridges;

[0056] Fig. 6 a detailed view of Fig. 5;

[0057] Fig. 7 a detailed view of a membrane cartridge in a mounted position between the intermediate walls.

[0058] Embodiments of the Invention

[0059] Fig. 1 shows a schematic representation of a membrane system 1 for gas separation using membrane technology, wherein a feed gas stream F is separated into a retentate gas stream R and a permeate gas stream P. The membrane (housing) system 1 has a housing 2, which forms the outer wall of the system 1. An inner space of the housing 2 system 1 is equipped with a plurality of membrane cartridges 3. Each membrane cartridge 3 has a

[0060] P248937 cartridge housing 30, a gas selective membrane (not shown) inside the housing 30, a feed inlet 31 for the feed gas F', a retentate outlet 32 for retentate gas R', and a permeate outlet 33 for permeate gas P'.

[0061] The inner space of the housing is divided into three subspaces 21 , 22, 23 by a first intermediate wall 4 and a second intermediate wall 5, namely a feed subspace 21 , a retentate subspace 22, and a permeate subspace 23.

[0062] The feed subspace 21 is formed by the wall of the housing 2 and the first intermediate wall 4. The feed subspace 21 is fluidly connected to a feed gas stream inlet 11 located in the wall of the housing 2 for feeding feed gas F into the membrane system 1.

[0063] The permeate subspace 23 is formed by the wall of the housing 2 and the second intermediate wall 5. The permeate subspace 23 is fluidly connected to a permeate gas stream outlet 13 in the wall of the housing 2. The permeate gas stream P leaves the membrane system 1 through the permeate gas stream outlet 13.

[0064] The retentate subspace 22 is formed between the feed subspace 21 and the permeate subspace 23 by the wall of the housing 2 and the first and second intermediate wall 4, 5. The retentate subspace 22 is fluidly connected to a retentate gas stream outlet 12 in the wall of the housing 2. The retentate gas stream R leaves the membrane system 1 through the retentate gas stream outlet 12.

[0065] Each membrane cartridge 3 is releasably into a mounted position between the first intermediate wall 4 and the second intermediate wall 5.

[0066] The first intermediate wall 4 comprises a first cartridge opening 41 for each membrane cartridge 3. The second intermediate wall 5 comprises a second cartridge opening 51 for each membrane cartridge 3. The membrane cartridge 3 is releasably placed in the first and second opening 41 , 51 and between the first and second intermediate wall 4, 5. The opening 41 , 51 may be provided with a sealing ring or an adapter.

[0067] In the shown membrane system, the membrane cartridge 3 is cylindrical with the feed inlet 31 at a first end 3a. The permeate outlet 33 is arranged at a second end 3b opposite the first end 3a. The retentate outlet 32 is arranged near the second end 3b of the membrane cartridge 3 and spaced apart from the permeate outlet 31 in axial direction of the membrane cartridge 3.

[0068] In a mounted position, the outer wall 30 of the membrane cartridge 3 near the first end 3a is placed in the first cartridge opening 41 in a sealing manner. Thus, the feed inlet 31 opens towards the feed subspace 21. The second end 3b with the permeate outlet 33 is placed

[0069] P248937 and sealed in the second cartridge opening 51 such the permeate outlet 33 opens towards the permeate subspace 23. Thus, the retentate outlet 32, which is between the feed inlet 31 and the permeate outlet 33 is located between the first intermediate wall 4 and the second intermediate wall 5 and opens towards the retentate subspace 22.

[0070] In operation of the membrane system, a feed gas stream F is feed through the feed gas stream inlet 11 into the feed subspace 21. From there the feed gas stream F directly enters each membrane cartridge 3 through the feed inlet 31 as partial feed gas streams F' which are the separated into partial retentate gas streams R' and partial permeate gas streams P'.

[0071] The partial permeate gas streams P' leave the membrane cartridges 3 through the permeate outlet 33 and are collected in the permeate subspace 23. From there the permeate gas stream P leaves the membrane system 1 through the permeate gas stream outlet 13 in the wall of the housing 2.

[0072] The partial retentate gas streams R' leave the membrane cartridges 3 through the retentate outlet 32 and are collected in the retentate subspace 22. From there the retentate gas stream R leaves the membrane system 1 through the retentate gas stream outlet 12 in the wall of the housing 2.

[0073] The volume of the feed subspace 21 is at least one third of the total volume of the housing 2. The large relative volume of the feed subspace 21 allows an energy efficient gas separation at low pressure with a high mass flow rate. During operation the absolute pressure in the feed subspace is typically between 1 and 1.5 resulting in an overpressure below 500 mbar. The large volume of the feed subspace allows an efficient distribution of the feed gas F to the feed inlets 31 of all the membrane cartridges 3, which may amount to several hundreds.

[0074] In the shown volume of the feed subspace 21 is about two fifths of the total volume of the housing.

[0075] Any tubes or pipes to connect the individual membrane cartridges 3 can thereby be avoided.

[0076] Depending on the location of the feed inlet, the retentate outlet and the permeate outlet the three subspaces may be located differently.

[0077] The feed inlet 31 of the membrane cartridge 3 or the cartridge housing 30 may extend over an upper surface of the first intermediate wall 4 facing the feed subspace 21 , and forms together with the housing 2 and the first intermediate wall 4 a condensate reservoir 6 to collect condensate in the feed subspace 21. Thereby condensate, which may accumulate

[0078] P248937 in the feed subspace, is prevented from entering the membrane cartridge 3 through the feed inlet 31 . The feed subspace 21 is further provided with a system for draining the condensate from the condensate reservoir 6. Such a condensate reservoir 6 and condensate drainage system are particularly useful when feeding the membrane system with flue gas. Flue gas typically contains large amounts of water.

[0079] In the shown membrane system, the intermediate walls are arranged horizontally, and the cylindrical membrane cartridges are arranged vertically. Alternatively, the intermediate walls may be arranged vertically, and the cylindrical membrane cartridges may be arranged horizontally.

[0080] The housing 2 may be a standard shipping container or any other large preferably rectangular box.

[0081] Fig. 2 shows a schematic representation of the membrane system of Fig. 1 . The height H2 of the retentate subspace 22 is smaller than the total length L of the membrane cartridge 3 allowing an arrangement of the cartridge 3 between the first and second intermediate wall 4, 5 and correct arrangement of the inlet and the outlets of the membrane cartridge 3 as described above. The height H1 of the feed subspace 21 is larger than the total length L of the membrane cartridge 3. Any membrane cartridge 3 can thus be easily placed in the first and second cartridge openings 41 , 51 of the first and second intermediate walls 4, 5 as shown by the arrow A. For maintenance and removal of the releasably mounted cartridges 3 from the housing 2, the cartridges 3 may be lifted out of the first and second openings 41 , 51 in an axial direction A of the cartridge 3 and then moved sideways, i.e. perpendicular to the axial direction A. The housing 2 may comprise a hatch or door in a side wall of the housing 2 for accessing the feed subspace 21 .

[0082] The feed subspace 21 may therefore be provide with a handling device for placing and removing membrane cartridges 3.

[0083] In the membrane system 1 shown in Fig. 2, the first intermediate wall 4 is arranged at the first end 3a of the membrane cartridges 3. Membrane cartridges 3 can be lifted over neighbouring membrane cartridges 3.

[0084] As shown in Fig. 3, the first intermediate wall 4 may be arranged near the centre of the membrane cartridges 3. This configuration may be useful for housings 2 with limited space. The membrane cartridges 3 can still be lifted out of the first and second cartridge openings 41 , 51 but the must be inserted or removed in series. A replacement of an individual membrane cartridge 3 from the side, i.e. in a direction parallel to the intermediate walls,

[0085] P248937 would not be possible. The setup of Fig. 2 allows removing and inserting any membrane cartridge 3 over neighbouring membrane cartridges 3.

[0086] The housing may be provided with an air-tight door or hatch in a side wall to access one or all three subspaces for maintenance. The feed subspace may be provided with a handling device for placement and removal of individual membrane cartridges or a group of membrane cartridges. Rails can be present at the roof of the feed subspace to guide a handling arm or handling crane to the desired position.

[0087] Fig. 4 shows a membrane system 1 with a permeate subspace formed by a separate gas tight box placed in the inner space of the housing 2. A side wall of the box forms the second intermediate wall 5. The box is fluidly connected with the permeate gas stream outlet 13. Such a configuration is particularly useful for applying a vacuum to the permeate subspace 23 as driving force for the gas separation.

[0088] Fig. 5 and Fig. 6 (detail of Fig. 5) show a drawing of membrane system in the form of a large shipping container (intermodal container) or similarly sized container, e.g. a standard high- cube 40 ft container. A front and side wall are not shown to reveal the interior of the membrane system. The drawings show a housing 2 with a first intermediate wall 4 and a second intermediate wall 5 dividing the inner space of the housing 2 into an upper feed subspace 21 , a middle retentate subspace 22 and a lower permeate subspace 23. The housing wall is provided with a feed gas stream inlet 11 , a retentate gas stream outlet 12 and a permeate gas stream outlet 13, which lead to the respective subspaces. The inlet and outlets can be arranged in any of side walls of the housing.

[0089] The first intermediate wall 4 and the second intermediate wall 5 are provided with several first cartridge openings 41 and second cartridge openings 51 respectively. Only a few of these openings are drawn on the right side of the container. The openings 41 , 51 accommodate the membrane cartridges 3 as explained above. Only a few cartridges are shown.

[0090] In operation, feed gas is fed through the feed gas stream inlet 11 into the membrane system and distributed over the entire feed subspace 21. From the feed subspace 21 the feed gas stream enters each membrane cartridge 3 in parallel. The retentate gas stream leaves the membrane cartridge 3 towards the retentate subspace 22. The retentate gas may move between the membrane cartridges and leaves the membrane system through the retentate gas stream outlet 12. Permeate gas stream leaves the membrane cartridge 3 towards the permeate subspace 23 and leaves the membrane system through the permeate gas stream outlet 13.

[0091] P248937 Several membrane systems can be placed and operated in series, in parallel or in combination thereof. A permeate gas stream may become the feed gas stream of a subsequent membrane system as known in the art. The membrane systems can also be stacked on top of each other.

[0092] Fig. 7 shows a detailed view of a membrane cartridge 3 in a mounted position between the intermediate walls 4, 5. The membrane cartridge 3 has a cylindric an outer wall 30, a gas selective membrane (not shown) within the outer wall, a feed inlet 31 , a retentate outlet 32 and a permeate outlet 33. The feed inlet 31 is arranged at a first end 3a of the membrane cartridge 3. The retentate outlet 32 and the permeate outlet 33 are arranged at a second end 3b of the membrane cartridge 3, the second end 3b being opposite the first end 3a. The permeate outlet 33 is defined by a tube 34 having a smaller diameter than the cylindric outer wall 30 of the cartridge 3. The tube 34 extends over the outer wall 30 in axial direction A of the cylindrical membrane cartridge 3. The retentate outlet 32 is arranged between the tube 34 and the outer wall 30.

[0093] The tube 34 may comprise a flange 35, which in a mounted position of the cartridge 3 rest on the second intermediate wall 5 within the retentate subspace 22. The tube 34 may be provided with a second cartridge seal 52 e.g. in the form of an O-ring, which in a mounted position of the cartridge 3 engages with the second cartridge opening 51. The outer wall 30 of the membrane cartridge 3 is spaced apart from the second intermediate wall 5 to leave enough space for the retentate outlet 32 between the outer wall 30 of the membrane cartridge 3 and the tube 34 of the permeate outlet 33.

[0094] The first cartridge opening 41 in the first intermediate wall 4 has a larger diameter than the second cartridge opening 51 and corresponds to the diameter of the outer wall 30 of the membrane cartridge 3. In a mounted position, the outer wall 30 engages with a first cartridge seal 42 provided in the first cartridge opening 41 in a sealing manner. The outer wall 30 may extend over the first intermediate wall 4 into the feed subspace 21 to form a condensate reservoir 6 as explained further above.

[0095] For easily mounting the membrane cartridge 3 within the membrane system, the membrane cartridge 3 may be slid in axial direction A from the feed subspace 21 through the first cartridge opening 41 until the tube 34 of the permeate outlet 34 is placed within the second cartridge opening 51. The cartridge 3 may be held in place by mere gravitational force and a slight clamping force of the first and second cartridge seals 42, 52. The flange 35 at the tube 34 of the permeate outlet 33 ensures correct placement of the cartridge 3 when sliding it into position.

[0096] P248937 To facilitate mounting, the volume of the feed subspace 21 is at least one third of the total volume of the housing of the membrane system providing enough space to insert the entire cartridge 3. Thus, it is not required to remove an entire top wall of the container for mounting individual cartridges.

[0097] Reference Signs

[0098] 1 membrane system

[0099] 11 feed gas stream inlet

[0100] 12 retentate gas stream outlet

[0101] 13 permeate gas stream outlet

[0102] 2 housing

[0103] 21 feed subspace

[0104] 22 retentate subspace

[0105] 23 permeate subspace

[0106] 3 membrane cartridge

[0107] 3a first end of membrane cartridge

[0108] 3b second end of membrane cartridge

[0109] 30 outer wall

[0110] 31 feed inlet

[0111] 32 retentate outlet

[0112] 33 permeate outlet

[0113] 34 tube

[0114] 35 flange

[0115] 4 first intermediate wall

[0116] 41 first cartridge opening

[0117] 42 first cartridge seal

[0118] 5 second intermediate wall

[0119] 51 second cartridge opening

[0120] P248937 52 second cartridge seal

[0121] 6 condensate reservoir

[0122] A axial direction

[0123] F, F' feed gas stream P, P' permeate gas stream

[0124] R, R' retentate gas stream

[0125] L length of membrane cartridge

[0126] H1 distance between housing wall and first intermediate wall I heights of feed subspace H2 distance between first and second intermediate wall I heights of retentate subspace

[0127] P248937

Claims

Claims1. Membrane system (1) for separating a feed gas stream (F) at low pressure into a retentate gas stream (R) and a permeate (P) stream, the system (1) comprising a housing (2) and a plurality of membrane cartridges (3) having a first end (3a) and an opposite second end (3b), wherein the housing (2) comprises a first intermediate wall (4) and a second intermediate wall (5) dividing an inner space of the housing (2) into a feed subspace (21), a retentate subspace (22) and a permeate subspace (23), wherein the membrane system (1) comprises in an outer wall of the housing (2) a feed gas stream inlet (11) fluidly connected to the feed subspace (21), a retentate gas stream outlet (12) fluidly connected to the retentate subspace (22), and a permeate gas stream outlet (13) fluidly connected to the permeate subspace (23); wherein each membrane cartridge (3) comprises an outer wall (30), a gas selective membrane, a feed inlet (31), a retentate outlet (32) and a permeate outlet (33), wherein each membrane cartridge (3) of the plurality of membrane cartridges (3) is releasably insertable into a mounted position between the first intermediate wall (4) and the second intermediate wall (5) such that the feed inlet (31) of each membrane cartridge (3) opens towards the feed subspace (21), the permeate outlet (33) of each membrane cartridge (3) opens towards the permeate subspace (22) and the retentate outlet (32) of each membrane cartridge (3) opens towards the retentate subspace (23), wherein the first end (3a) of each of the plurality of membrane cartridges (3) is arranged at the first intermediate wall (4) and the second end (3b) of each of the plurality of membrane cartridges (3) is arranged at the second intermediate wall (5); wherein the volume of the feed subspace (21) is at least one third of the total volume of the housing (2).

2. Membrane system according to claim 1 , wherein the feed inlet (31) is arranged at the first end (3a) of the membrane cartridge (3), the permeate outlet (33) is arranged atP248937the second end (3b) of the membrane cartridge (3) and the retentate outlet (32) is arranged between the feed inlet (31) and the permeate outlet (33).

3. Membrane system according to one of the preceding claims, wherein the first intermediate wall (4) comprises a first cartridge opening (41) for every membrane cartridge (3) of the plurality of membrane cartridges (3) and wherein the second intermediate wall (5) comprises a second cartridge opening (51) for every membrane cartridge (3) of the plurality of membrane cartridges (3).

4. Membrane system according to one of the preceding claims, wherein the feed inlet (31) of the membrane cartridge (3) or the cartridge housing (30) extends over an upper surface of the first intermediate wall (4) facing the feed subspace (21), and forms together with the housing (2) and the first intermediate wall (4) a condensate reservoir (6).

5. Membrane system according to one of the preceding claims, wherein the membrane cartridge (3) is a cylindrical cartridge.

6. Membrane system according to claims 4, wherein the first cartridge opening (41) has the same size or is larger than the second cartridge opening (51).

7. Membrane system according to one of claims 4 to 6, wherein the first cartridge opening (41) and / or the second cartridge opening (51) is provided with an adapter.

8. Membrane system according to one of the preceding claims, wherein the housing (2) is a standard shipping container.

9. Membrane system according to one of the preceding claims, wherein the first intermediate wall (4) and the second intermediate wall (5) are arranged horizontally within the housing (2) and the plurality of membrane cartridges (3) are arranges vertically, or wherein the first intermediate wall (4) and the second intermediate wall (5) are arranged vertically within the housing (2) and the plurality of membrane cartridges (3) are arranges horizontally.

10. Membrane system according to one of the preceding claims, wherein a distance (H2) between the first intermediate wall (4) and the second intermediate wall (5) is smaller than the total length (L) of the membrane cartridge (3).P24893711. Membrane system according to one of the preceding claims, wherein a distance (H1) in the feed subspace (21) between the first intermediate wall (4) and the wall of the housing (2) is larger than the total length (L) of the membrane cartridge (3).

12. Membrane system according to one of the preceding claims, wherein the housing (2) is provided with a door in a side wall.

13. Membrane system according to one of the preceding claims, wherein the membrane system (1) is provided with handling means for placement or removal of the plurality of membrane cartridges (3).

14. Process for separating a feed gas stream (F) at low pressure into a retentate gas stream (R) and a permeate (P) stream using a membrane system according to one of the preceding claims, the process comprising the steps of: a. feeding a feed gas stream (F) to the feed gas stream inlet (11) of the membrane system; b. recovering a permeate gas stream (P) from the permeate gas stream outlet (13).

15. Process according to claim 14, wherein the permeate gas stream is selected from the group of olefin separated from flare gas as feed gas stream, CO2 separated from flue gas as feed gas stream or hydrogen separated from a methane feed gas stream.P248937

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