Tubular connecting member for membrane filtration system

Abstract

A tubular connecting member configured to interconnect a plurality of tubular members in a fluid flow system, the tubular connecting member comprising: - at least one primary outlet having a primary inflow / outflow direction, configured to connect to its outer end a primary tubular element having a cylindrical cross-section at least at its outer end; and - at least one secondary outlet having a secondary inflow / outflow direction, configured to connect to its outer end a secondary tubular element having a cylindrical cross-section at least at its outer end, wherein the secondary inflow / outflow direction is positioned at a non-zero angle with respect to the primary inflow / outflow direction, and the secondary outlet further comprises an inner portion having a non-circular, particularly elliptical, cross-section when viewed in a plane substantially perpendicular to the secondary inflow / outflow direction.

Description

Technical Field

[0001] The present invention relates to a tubular connection member configured to interconnect a plurality of tubular members in a fluid flow system, and a fluid flow system such as a membrane filtration system including such a tubular connection member.

Background Art

[0002] Membrane filtration systems typically include a plurality of tubular filtration units arranged in parallel, with membrane filters disposed to filter the liquid flowing through the filtration units. These filtration units are typically connected to supply and / or discharge lines using T-shaped tubular connection pieces (i.e., joints) made of a plastic material. However, due to high pressures in the range of 3 to 10 bar, the T-shaped tubular connection pieces need to have a relatively thick outer wall to keep the material stress, especially at the critical location at the base of the T-shape, below a specific material-dependent stress threshold in order to ensure a sufficient lifespan of the T-shaped connection pieces, and often below the fatigue stress limit. The relatively thick walls lead to a relatively expensive manufacturing process for these connection pieces.

[0003] Furthermore, due to the flow characteristics of such membrane filtration systems, the liquid flow is not evenly distributed across different membrane filtration units, leading to a decrease in the overall performance of the system.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention aims to provide a tubular connection member configured to interconnect a plurality of tubular members in a fluid flow system, such as a membrane filtration system, which improves the flow characteristics of such a system, is easier to manufacture, and is less expensive.

Means for Solving the Problems

[0005] In a first embodiment, the present invention relates to a tubular connecting member configured to interconnect a plurality of tubular members in a fluid flow system, wherein the tubular connecting member is - At least one primary outlet having a primary inflow / outflow direction, and in particular configured to have a primary tubular element having a cylindrical cross-section at least at its outer end connected to the outer end, - comprising at least one secondary outlet having a secondary inflow / outflow direction, and in particular configured to have at least one secondary tubular element having a cylindrical cross-section at its outer end connected to its outer end, The secondary inflow / outflow directions are positioned at a non-zero angle with respect to the primary inflow / outflow directions. The secondary outlet further comprises an inner portion having a non-circular, particularly elliptical, cross-section when viewed in a plane substantially perpendicular to the secondary inflow / outflow direction.

[0006] Such tubular connectors, due to the non-circular cross-section of the inner portion, allow for a reduction in the stress concentration factor at the base of the tubular connector where the primary and secondary outlets are joined, thereby reducing critical stress. This allows for a reduction in the overall wall thickness of the tubular connector, making it possible to manufacture the tubular connector efficiently and at low cost using molding processes such as injection molding or additive manufacturing. The non-circular cross-section further allows for tuning the flow characteristics of the tubular connector, and consequently the flow characteristics of the membrane filtration system, enabling more uniform flow from the secondary outlet of the tubular connector. Thus, if each secondary outlet of such a tubular connector is connected to multiple parallel filtration units, the non-circular cross-section allows for more uniform flow through the different filtration units. As the liquid flow is distributed more uniformly across the different filtration units, the overall performance of the system is improved.

[0007] The inner portion extends inward relative to the outer end of the secondary outlet. That is, when viewed along the flow path from the primary outlet to the secondary outlet through the tubular connecting member, the inner portion is located between the primary outlet and the outer end of the secondary outlet. More specifically, for example, in the case of a T-shaped connecting piece, the inner portion may be located at the base of the T-shape.

[0008] Tubular connecting members, particularly primary components, may have a circular cross-section, such as a circle, or a polygonal cross-section, such as a square or triangle. For example, as seen in the cross-section, the periphery of the connecting member may be formed as a square, truncated circle, rounded square, rounded quadrilateral, or similar shape. Therefore, the term “tubular” is not limited to a cylindrical shape. Preferably, the flow channel through the tubular connecting member has a substantially circular cross-section, apart from the non-circular inner portion of the secondary outlet.

[0009] Preferably, the non-circular cross-section of the inner portion has a major axis and a minor axis, the width of the non-circular cross-section is greater along the major axis than along the minor axis, and is particularly maximum, and the major axis of the non-circular cross-section is positioned at a non-zero angle with respect to the primary inflow / outflow direction. Such a configuration leads to a reduction in swirling disturbances at the secondary outlet that adversely affect the flow through the outlet. This results in a more uniform flow through the different filtration units of the membrane filtration unit.

[0010] To optimize this effect, the non-circular cross-section of the inner portion is more preferably a substantially elliptical cross-section having a major axis substantially perpendicular to the primary inflow / outflow direction and a minor axis substantially parallel to the primary inflow / outflow direction.

[0011] The primary outlet may be connected to a tubular element using annular clamps mounted around each of its outer ends. Since the width of the inner portion of the secondary outlet is smaller along the axis parallel to the primary inflow / outflow direction, the length of the primary outlet can be shortened to obtain a more compact connecting piece while leaving sufficient space for mounting the clamps. In this way, a more compact fluid flow system can be obtained overall.

[0012] In a preferred embodiment, the diameter of the circular cross-section of the outer portion of the primary outlet is smaller than the diameter of the circular cross-section of the outer portion of the secondary outlet. This allows a membrane filtration unit having a tubular housing generally with a diameter of 12 inches or less, or 10 inches or less, typically about 8 inches (about 20 cm), to be directly connected to the secondary outlet, while a feed pipe generally with a diameter of at least 4 inches, typically about 6 inches (about 15 cm), can be directly connected to the primary outlet. This reduces the need for further separate adapters in such a membrane filtration system. More generally, therefore, it is preferable that the diameter of the outer outlet of the connecting member corresponds to the diameter of the outer end of the tubular element to which the connecting member is connected, so that the connecting member can be directly connected to each outer end of the tubular element. Thus, for example, a connecting member having two or three equal outlet outer diameters can also be envisioned.

[0013] In this specification, for example, “outer end” and “outer portion” may be used interchangeably and may generally relate to or refer to the free end of each outlet, which extends outward in particular to connect to a tubular element.

[0014] The primary outlet preferably has an inner portion extending inward from the outer portion, the inner portion having a peripheral wall, and the inner portion of the secondary outlet is formed as a through-hole penetrating the peripheral wall of the inner portion of the primary outlet. By selecting the shape of the through-hole, a non-circular cross-section of the inner portion can be formed.

[0015] It is even more preferable that the width of the major axis of the non-circular cross-section of the inner portion of the secondary outlet is less than or equal to the maximum width of the inner portion of the primary outlet through which the inner portion of the secondary outlet extends, and that the inner portion of the primary outlet has a substantially circular cross-section when viewed in a plane perpendicular to the primary inflow / outflow direction. Then, it is even more preferable that the major axis of the non-circular cross-section of the inner portion of the secondary outlet is less than or equal to the diameter of the circular cross-section of the inner portion of the primary outlet. By forming a non-circular cross-section in this way, the swirling disturbances described above can be effectively reduced.

[0016] In a preferred embodiment, the tubular connecting element further comprises a tertiary outlet for connecting a tertiary tubular element to its outer portion. This makes it possible to connect further tubular elements to the tubular connecting piece, for example, to add a plurality of parallel-arranged membrane filtration units. The tertiary outlet is then a second primary outlet having a second primary inflow / outflow direction, and the second primary outlet is configured to connect to a primary tubular element having a cylindrical cross-section at least at its outer end. The second primary inflow / outflow direction is substantially parallel to or equal to the primary inflow / outflow direction, and / or the central axis of the outer portion of the primary outlet is substantially parallel to, and more preferably coaxial with, the central axis of the outer portion of the second primary outlet.

[0017] This further allows for the formation of supply or discharge pipes by connecting adjacent primary outlets of adjacent tubular connecting elements, thereby further improving the overall flow characteristics of the system. Therefore, preferably, the tubular connecting elements are formed to include at least a T-shaped joint.

[0018] The tubular connecting element may have a plurality of secondary outlets, each having its own secondary inflow / outflow direction, and each secondary outlet is configured to connect to a secondary tubular element having a cylindrical cross-section at least at its outer end. Each secondary inflow / outflow direction is positioned at a non-zero angle with respect to the primary inflow / outflow direction. Each secondary outlet further comprises an inner portion having a non-circular cross-section, particularly an elliptical cross-section, when viewed in a plane substantially perpendicular to the secondary inflow / outflow direction.

[0019] This makes it possible to connect multiple membrane filtration units to a single tubular connector while benefiting from the improved flow characteristics described above.

[0020] Preferably, the primary outlet(s) are formed from substantially cylindrical tubular elements, and the outer(s) are positioned at each(ends) of the substantially cylindrical tubular element such that the primary inflow / outflow direction is substantially parallel to the central axis of the cylindrical tubular element. A substantially straight and unobstructed primary flow path can be obtained, thereby further improving the overall flow characteristics.

[0021] In a preferred embodiment, each outlet is provided with fixing means for permanently connecting each cylindrical tubular element thereto, the fixing means preferably comprising engaging means such as circumferential projections or recesses located on or within the outer surface of each outlet. The fixing means preferably includes a connecting bracket configured to be attached to the outer circumferential surface of each outlet, The engaging means is preferably configured to receive a connecting bracket on which the outlet will be interconnected to each primary or secondary tubular element arranged with similar cooperating engaging means. By positioning the fixing means on the outer surface of the tubular connecting element, a substantially straight and unobstructed primary flow path can be obtained through the series of connected tubular elements and / or tubular connecting elements, thereby further improving the overall flow characteristics of the membrane filtration unit.

[0022] Preferably, the tubular connection member is monolithic. To economically obtain a monolithic tubular connection element with favorable properties, it is preferably made from a plastic material, particularly a reinforced plastic material, or from a metal such as steel, especially by means of a casting process. For example, the connection member may be made by an overmolding technique. Alternatively, the monolithic tubular connection member may be made by welding. For example, the secondary outlet may be connected to the primary outlet by welding.

[0023] The tubular connection member is preferably an elbow-shaped connection member having only one primary outlet and only one secondary outlet, and preferably, the primary and secondary inflow / outflow directions are arranged at an angle of 45° or 90° to each other.

[0024] Alternatively, the tubular connection member is preferably a T-shaped connection member having only two primary outlets and only one secondary outlet, and preferably, the primary and secondary inflow / outflow directions are arranged at an angle of 45° or 90° to each other. Such a tubular connection member enables improved overall flow characteristics of the membrane filtration system.

[0025] The fluid flow system can be any system through which a fluid can flow. The term "fluid" is not limited to liquids such as water and may also refer to gases. Thus, the fluid flow system may be any system in which a pressure drop of the fluid can occur, such as a membrane filtration system or a carbon capture system. Accordingly, a fluid flow system is provided that includes a plurality of tubular elements for a fluid to flow through, and the system further includes at least one tubular connection member according to any of the above embodiments, the tubular connection member interconnects the tubular elements of the plurality of tubular elements, the primary outlet of the tubular connection member connects the primary tubular element of the plurality of tubular elements at its outer end, the primary tubular element has a cylindrical cross-section at least at its outer end, the secondary outlet of the tubular connection member connects the secondary tubular element of the plurality of tubular elements at its outer end, and the secondary tubular element has a cylindrical cross-section at least at its outer end.

[0026] In a second aspect, the present invention relates to a method of manufacturing, by a casting process, a tubular connecting member according to any of the foregoing embodiments in a single piece.

[0027] In a third aspect, the present invention relates to a fluid flow system comprising a supply line for supplying a fluid to be processed and a discharge line for discharging the fluid after processing, and further comprising at least one fluid processing unit disposed between the supply line and the discharge line and having an inlet and an outlet, the fluid processing unit being configured such that in use the fluid flows from the supply line to the discharge line, thereby passing through the fluid processing unit. At least one of the inlet and the outlet has a cylindrical cross-section. The system further comprises at least one tubular connecting member according to any of the preceding embodiments, the tubular connecting member interconnecting at least one of the inlet and the outlet to the supply line or the discharge line, respectively.

[0028] Thereby, it becomes possible to obtain a fluid flow system having improved flow characteristics with an improved connecting member as described above therein.

[0029] Preferably, the secondary outlet of the tubular connecting member is connected to at least one of the inlet and the outlet of the fluid processing unit, and the primary outlet of the tubular connecting member is connected to the supply line or the discharge line, respectively. In a preferred embodiment, the housing of the fluid processing unit is substantially tubular with a cylindrical cross-section, the inlet and the outlet are disposed at opposite ends of the housing shaped into respective tubes, a first tubular connecting member interconnects the inlet to the supply line, and a second tubular connecting member interconnects the outlet to the discharge line. Thereby, an improved system having the above advantages is obtained.

[0030] The fluid flow system preferably comprises a plurality of fluid processing units arranged substantially parallel to one another, and a plurality of tubular connecting members for interconnecting the plurality of fluid processing units to supply lines and discharge lines. Furthermore, it is more preferable that each inlet of each fluid processing unit is connected to a secondary outlet of the respective first tubular connecting member, each outlet of each fluid processing unit is connected to a secondary outlet of the respective first tubular connecting member, adjacent first tubular connecting members are coupled via primary outlets to form a supply line, and adjacent second tubular connecting members are coupled via primary outlets to form a discharge line.

[0031] As a result, a more uniform flow distribution is achieved across the fluid processing unit, as described above.

[0032] The fluid flow system may be a membrane filtration system, the supply line is for supplying the liquid to be filtered, and each fluid processing unit is a membrane filtration unit comprising a housing having an inlet, an outlet, and a filtration membrane between them, the membrane filtration unit is configured such that when in use, the liquid flows from the inlet to the outlet and thereby passes through the filtration membrane.

[0033] Alternatively, the fluid flow system may be a carbon capture system for capturing carbon dioxide from a gas mixture from a source such as an industrial source, the supply line is for supplying the gas mixture from which carbon dioxide is captured, and each fluid processing unit is a carbon capture unit for removing carbon dioxide from the mixture. The carbon capture unit is, for example, an sorption unit or membrane gas separation unit having a housing with an inlet, an outlet and a gas separation membrane between them. The discharge line is then for discharging the captured carbon dioxide or for discharging the gas mixture after carbon dioxide has been captured. The overall performance of the carbon capture system is improved because the liquid flow is distributed more uniformly across different sorption units or membrane gas separation units due to the non-circular cross-section of the tubular connecting members. The present invention is further illustrated by the following drawings, which illustrate preferred embodiments of the invention and are not intended to limit the scope of the invention in any way. [Brief explanation of the drawing]

[0034] [Figure 1] This is a schematic diagram of a membrane filtration system in which a supply solution can be pumped through eight parallel-connected membrane filtration units, and the flow rate and pressure can be adjusted by valves. [Figure 2] This is a schematic diagram showing a three-dimensional perspective view of a T-shaped tubular connecting element according to one embodiment of the present invention. [Figure 3] This is a schematic top view of a T-shaped tubular connecting element. [Figure 4] This is a schematic diagram of a three-dimensional cross-section of a T-shaped tubular connecting element cut along its longitudinal axis. [Figure 5] This is a schematic diagram of a cross-sectional view of a T-shaped tubular connecting element perpendicular to the longitudinal axis, in a front view along the longitudinal axis. [Figure 6A] This is a schematic diagram comparing the results from computational fluid dynamics (CFD) simulations of flow in membrane filtration systems using a T-shaped connecting element according to the prior art and a T-shaped connecting element according to the present invention, similar to the one shown in Figure 1. [Figure 6B] This is a schematic diagram comparing the results from computational fluid dynamics (CFD) simulations of flow in membrane filtration systems using a T-shaped connection element according to the prior art and a T-shaped connection element according to the present invention, similar to that shown in Figure 1. [Figure 7] This figure shows a comparison of flow in membrane filtration systems using a T-shaped connecting element according to prior art and a T-shaped connecting element according to the present invention, respectively, as shown in a bar graph. [Modes for carrying out the invention]

[0035] Figure 1 shows a membrane filtration system 1000 in which a supply solution can be pumped by a pump 1009 through eight parallel-connected membrane filtration units 1001-1008, and the flow rate and pressure can be adjusted by a valve 1010. Pressure and temperature can be measured by pressure sensors 1011, 1012 and temperature sensor 1013. The system is found to include a supply line 1100 for supplying the supply solution (i.e., the liquid to be filtered) to the membrane filtration units 1001-1008, a filtered liquid discharge line 1200 for collecting the liquid filtered by the membrane filtration units 1001-1008, and a waste mixture filtered from the supply solution, also called "substandard" or "concentrate," for discharge. In the current system 1000, membrane filtration units 1001 to 1007 are connected to the supply line by T-shaped tubular connecting elements 1, as shown in detail in Figures 2 to 5, while the final membrane filtration unit 1008 is connected by an elbow-shaped tubular connecting element (not shown in detail) according to the present invention.

[0036] Figures 2 to 5 show the T-shaped tubular connector element 1 in more detail, and it can be seen that the T-shaped tubular connector element 1 has two primary outlets 10 which can be connected to a supply line or a discharge line, and a single secondary outlet 20 which can be connected to the cylindrical housing of the membrane filtration units 1001 to 1008 shown in Figure 1. The T-shaped tubular connector element 1 further comprises a bracket 50 for connecting the T-shaped tubular connector element 1 to a frame and / or similar support member. The T-shaped tubular connecting element 1 is preferably formed integrally by injection molding from metal or plastic, such as polybutylene terephthalate (PBT), polyamide (PA), polyethylene (PE), polypropylene (PP), polyethersulfone (PES), polysulfone (PSU), polyvinyl chloride (PVC), or polylactic acid (PLA), particularly high-performance plastics, such as styrene-based resins (e.g., acrylonitrile butadiene styrene (ABS)) or amorphous blends of polyphenylene ether and polystyrene (PPE / PS) or amorphous blends of polyphenylene ether and polyamide (PPE / PA). The tubular connecting element 1 may also be made from a fiber-reinforced composition such as glass fiber, preferably containing at least one of the above materials.

[0037] The T-shaped tubular connecting element 1 comprises two primary outlets 10 having a primary inflow / outflow direction I, and the primary outlets 10 are configured to connect to primary tubular elements having a cylindrical cross-section at least at their outer ends. The outer portion 13 is located therein with a circular cross-section. Between each of the (tubular) outer portion 13 of the two primary outlets 10 is an (tubular) inner portion 14 that interconnects the respective outer portion 13. The outer portion 13 and the inner portion 14 thus effectively form a substantially linear tubular member having a primary central axis AI extending parallel to the primary inflow / outflow direction I.

[0038] The secondary outlet 20, which extends effectively from the inner portion 14 of the primary outlet, has a secondary inflow / outflow direction II, and the secondary outlet 20 is configured to connect to its outer end 21 a secondary tubular element having a cylindrical cross-section at least at its outer end. The outer portion 23 is located here with a circular cross-section. The inner portion 24 of the secondary outlet 20 is located between the inner portion 14 of the primary outlet 10 and the outer portion 21 of the secondary outlet 20 and includes a substantially non-circular (inner) cross-section, as is best seen in Figure 3. Thus, the secondary outlet 20 extends through the inner portion 14 of the primary outlet 10, particularly its peripheral wall, by a non-circular, in particular elliptical through-hole 25. As previously mentioned, it can be seen that the cross-section of the outer end 21 of the secondary outlet 20 has a larger diameter than the cross-section of the outer end 11 of the primary outlet 10.

[0039] As a result, the primary outlet 10 and the secondary outlet 20 form a T-shaped tubular connecting member (or T-shaped joining member), thereby allowing the flow of liquid entering one of the primary outlets 10 to be directed to the other of the primary outlets 10 and the secondary outlet, while the flow of liquid entering through the secondary outlets 20 to be directed to each of the primary outlets 10. The secondary outlet 20 is positioned between the inner portion 24 and the outer portion 23 and includes an intermediate portion 26 formed as an effective shape transition component to adapt to the difference in the cross-sectional shapes of the respective inner portion 24 and outer portion 23.

[0040] The non-circular cross-section of the inner portion 24 has a major axis III and a minor axis IV, and the width of the non-circular cross-section is greatest along the major axis III. The major axis III of the non-circular cross-section is positioned at a non-zero angle with respect to the primary inflow / outflow direction I. In this embodiment, the major axis III is positioned substantially perpendicular to the primary inflow / outflow direction I. The width w2 of the major axis III of the elliptical cross-section of the inner portion 24 of the secondary outlet 20 is less than or equal to the maximum width w1 corresponding to the inner diameter of the inner portion 14 of the primary outlet 10 through which the inner portion 24 of the secondary outlet extends.

[0041] Figure 4 shows that, in order to further reduce the stress concentration factor at the base portion 30 where the primary outlet 10 and the secondary outlet 20 are joined, the wall thickness of at least the primary outlet 10 increases toward the center of the inner portion 14, with the maximum thickness occurring at or near the center of the inner portion 14.

[0042] It can be seen that the outer surfaces 11, 21 of the primary outlet 10 and the secondary outlet 20, respectively, are provided with circumferential recesses 111, 211 located at the ends of the respective surfaces near the respective outer ends 12, 22 of the primary outlet 10 and the secondary outlet 20. These circumferential recesses 111, 211, as part of the fastening means, form engaging means for receiving one end of a connecting bracket (not shown) configured to be attached to the outer circumferential surface 11, 21 of the respective outlets 10, 20 to interconnect the outlets 10, 20 to the respective primary or secondary tubular elements arranged with similar cooperating engaging means.

[0043] Figures 6A and 6B schematically show a comparison of results from computational fluid dynamics (CFD) simulations of flow in a portion of a membrane filtration system 1000 using a T-shaped connecting element 1' from the prior art and a T-shaped connecting element according to the present invention 1, similar to that shown in Figure 1. Parallel-arranged membrane filtration units 1002 to 1004, each having a cylindrical housing 101, are connected by interconnected tubular connecting members 1 and 1' to a supply line 1100, which is formed by interconnecting their adjacent primary outlets 10 and 10' in particular. The cylindrical housings 101 are connected to their respective secondary outlets 20 and 20'. As seen in Figure 6B, compared to the secondary outlet 20' in Figure 6A, the swirl at the secondary outlet 20 is reduced, thereby resulting in improved flow-through and more uniform flow through the respective membrane filtration units 1002 to 1004.

[0044] The improved flow characteristics provided by the flow-through are further confirmed by the results shown in Figure 7, where the average axial flow velocity per membrane filtration unit of a membrane filtration system comprising 25 parallel-arranged membrane filtration units M1 to M25 is determined for both the system 1000 with a T-shaped connector 1' according to the prior art, i.e., a simple T-shaped tubular connector with a circular cross-section for each respective outlet, and the system with a T-shaped connector 1 shown in Figures 2 to 5. The normalized results are shown for each membrane filtration unit, where the left bar R1 of each represents the average axial flow velocity of the system according to the prior art, and the right bar R2 of each represents the average axial flow velocity of the system according to the present invention. Clearly, the use of the T-shaped tubular connector according to the present invention results in a more uniform and therefore improved flow-through.

[0045] The present invention is not limited to the embodiments shown, but also extends to other embodiments that fall within the scope of the appended claims. [Explanation of symbols]

[0046] 1. T-shaped tubular connecting element 1' T-shaped tubular connecting element 10 Primary exit 10' primary exit 11 Exterior 12 Outer edge 13 Outer part 14 Inner part 20 Secondary exit 20' Secondary exit 21 Exterior 22 Outer edge 23 Outer part 24 Inner part 25 Through holes 26 Middle part 30 Base 50 brackets 101 Housing 111 Circumferential recess 211 Circumferential recess 1000 Membrane Filtration System 1001-1008 Membrane Filtration Unit 1009 Pump 1010 Valve 1011 Pressure Sensor 1012 Pressure Sensor 1013 Temperature Sensor 1100 supply line 1200 discharge line 1300 Non-standard product line AI primary center axis I Primary inflow / outflow direction II Secondary inflow / outflow direction III Long axis IV short axis R1 Left bar R2 Right bar w1 maximum width w2 width

Claims

1. A tubular connecting member configured to interconnect multiple tubular members in a fluid flow system, - At least one primary outlet having a primary inflow / outflow direction, wherein the at least one primary outlet is configured to have a primary tubular element connected to its outer end, and the primary tubular element has a cylindrical cross-section at least at its outer end, and the at least one primary outlet is configured to have a primary tubular element connected to its outer end, - A secondary outlet having a secondary inflow / outflow direction, wherein the at least one secondary outlet is configured to have a secondary tubular element connected to its outer end, and the secondary tubular element has a cylindrical cross-section at least at its outer end, comprising at least one secondary outlet, The aforementioned secondary inflow / outflow direction is at a non-zero angle with respect to the aforementioned primary inflow / outflow direction. The secondary outlet is a tubular connecting member further comprising an inner portion having a non-circular cross-section when viewed in a plane perpendicular to the secondary inflow / outflow direction.

2. The tubular connecting member according to claim 1, wherein the non-circular cross-section of the inner portion has a major axis and a minor axis, the width of the non-circular cross-section is greatest along the minor axis, and the major axis of the non-circular cross-section is positioned at a non-zero angle with respect to the primary inflow / outflow direction.

3. The tubular connecting member according to claim 2, wherein the non-circular cross-section of the inner portion has a substantially elliptical cross-section having a major axis substantially perpendicular to the primary inflow / outflow direction and a minor axis substantially parallel to the primary inflow / outflow direction.

4. The tubular connecting member according to claim 3, wherein the non-circular cross-section of the inner portion is the inner cross-section of the secondary outlet.

5. The tubular connecting member according to any one of claims 1 to 4, wherein the secondary outlet has an outer portion, and the inner portion of the secondary outlet is located between the primary outlet and the outer portion of the secondary outlet when viewed along the flow path from the primary outlet through the tubular connecting member to the secondary outlet.

6. The tubular connecting member according to claim 5, wherein the outer portion of the secondary outlet has a circular cross-section, and the primary outlet has an outer portion having a circular cross-section, and the diameter of the circular cross-section of the outer portion of the primary outlet is smaller than the diameter of the circular cross-section of the outer portion of the secondary outlet.

7. The tubular connecting member according to any one of claims 1 to 6, wherein the primary outlet comprises an inner portion extending inward from the outer portion, the inner portion comprises a peripheral wall, and the inner portion of the secondary outlet is formed as a through hole penetrating the peripheral wall of the inner portion of the primary outlet.

8. The tubular connecting member according to claim 1 or 2 and 7, wherein the width of the major axis of the non-circular cross-section of the inner portion of the secondary outlet is less than or equal to the maximum width of the inner portion of the primary outlet through which the inner portion of the secondary outlet extends, and preferably, when viewed in a plane perpendicular to the primary inflow / outflow direction, the inner portion of the primary outlet has a substantially circular cross-section, and the major axis of the non-circular cross-section of the inner portion of the secondary outlet is less than or equal to the diameter of the circular cross-section of the inner portion of the primary outlet.

9. A tubular connecting member according to any one of claims 1 to 8, further comprising a tertiary outlet for connecting a tertiary tubular element to its outer portion.

10. The tertiary outlet is a second primary outlet having a second primary inflow / outflow direction, the second primary outlet is configured to be connected to a primary tubular element, and the primary tubular element has a cylindrical cross-section at least at its outer end. The tubular connecting member according to claim 9, wherein the second primary inflow / outflow direction is substantially parallel to or equal to the primary inflow / outflow direction, and / or the central axis of the outer portion of the primary outlet is substantially parallel to the central axis of the outer portion of the second primary outlet, and in particular coaxial with the central axis of the outer portion of the second primary outlet.

11. It has multiple secondary outlets, each secondary outlet having its own secondary inflow / outflow direction, and each secondary outlet is configured to be connected to its own secondary tubular element, and the secondary tubular element has a cylindrical cross-section at least at its outer end. Each secondary inflow / outflow direction is at a non-zero angle with respect to the primary inflow / outflow direction. The tubular connecting member according to any one of claims 1 to 10, wherein each secondary outlet further comprises an inner portion having a non-circular cross-section when viewed in a plane perpendicular to the secondary inflow / outflow direction.

12. A tubular connecting member according to any one of claims 1 to 11, wherein the primary outlet(s) are formed from substantially cylindrical tubular elements, and the outer portions(s) are positioned at each end(s) of the substantially cylindrical tubular elements such that the primary inflow / outflow direction is substantially parallel to the central axis of the cylindrical tubular elements.

13. Each of the outlets is provided with fixing means for permanently connecting each cylindrical tubular element thereto, and the fixing means preferably includes engaging means such as circumferential projections or recesses located on or within the outer surface of each outlet. The fixing means preferably comprises a connecting bracket configured to be attached to the outer circumferential surface of each of the outlets, The tubular connecting member according to any one of claims 1 to 12, wherein the engaging means is preferably configured to receive the connecting bracket thereon for interconnecting the outlet to each primary or secondary tubular element arranged with similar cooperating engaging means.

14. The tubular connecting member according to any one of claims 1 to 13, wherein the tubular connecting member is made from a plastic material, particularly a reinforced plastic material, by a casting process.

15. The tubular connecting member is an elbow-shaped connecting member having only one primary outlet and only one secondary outlet, preferably the primary inflow / outflow direction and the secondary inflow / outflow direction are arranged at an angle of 45° or 90° to each other, according to any one of claims 1 to 14.

16. The tubular connecting member is a T-shaped connecting member having only two primary outlets and only one secondary outlet, preferably the primary inflow / outflow direction and the secondary inflow / outflow direction are arranged at an angle of 45° or 90° to each other, according to any one of claims 1 to 14.

17. The tubular connecting member according to any one of claims 1 to 16, wherein the tubular connecting member is monolithic.

18. A method for manufacturing a tubular connecting member according to any one of claims 1 to 17 in a single piece by a casting process.

19. A fluid flow system comprising a supply line for supplying a fluid to be processed, and a discharge line for discharging the fluid after processing, further comprising at least one fluid processing unit disposed between the supply line and the discharge line and having an inlet and an outlet, wherein the fluid processing unit is configured such that, in use, the fluid flows from the supply line to the discharge line and thereby passes through the fluid processing unit. At least one of the inlet and the outlet has a cylindrical cross-section. The system further comprises at least one tubular connecting member according to any one of claims 1 to 17, wherein the tubular connecting member interconnects at least one of the inlet and outlet to the supply line or the discharge line, respectively, as a fluid flow system.

20. The fluid flow system according to claim 19, wherein the secondary outlet of the tubular connecting member is connected to at least one of the inlet and outlet of the fluid processing unit, and the primary outlet of the tubular connecting member is connected to the supply line or the discharge line, respectively.

21. The fluid flow system according to any one of claims 19 to 20, wherein the fluid processing unit is substantially tubular having a cylindrical cross-section, the inlet and outlet are located at both ends of the respective tubularly formed fluid processing unit, a first tubular connecting member interconnects the inlet to the supply line, and a second tubular connecting member interconnects the outlet to the discharge line.

22. A fluid flow system according to any one of claims 19 to 21, comprising a plurality of fluid processing units arranged substantially parallel to each other, and a plurality of tubular connecting members according to at least claim 9 or 10 for interconnecting the plurality of fluid processing units to the supply line and the discharge line.

23. The fluid flow system according to claim 22, wherein each inlet of each fluid processing unit is connected to a secondary outlet of the respective first tubular connector, each outlet of each fluid processing unit is connected to a secondary outlet of the respective first tubular connector, adjacent first tubular connectors are coupled via the primary outlet to form the supply line, and adjacent second tubular connectors are coupled via the primary outlet to form the discharge line.

24. The fluid flow system according to any one of claims 19 to 23, wherein the fluid flow system is a membrane filtration system, the supply line is for supplying a liquid to be filtered, and each fluid processing unit is a membrane filtration unit comprising a housing having an inlet, an outlet, and a filtration membrane between them, and the membrane filtration unit is configured such that when in use, a liquid flows from the inlet to the outlet and thereby passes through the filtration membrane.

25. The fluid flow system is a carbon capture system for capturing carbon dioxide from a gas mixture from a supply source such as an industrial supply source, the supply line is for supplying the gas mixture from which the carbon dioxide is captured, and each fluid processing unit is a carbon capture unit, according to any one of claims 19 to 23.

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