WO2024217651A1

WO2024217651A1 - Multi-layered diaphragm for a high-pressure compressor

Info

Publication number: WO2024217651A1
Application number: PCT/DK2024/050092
Authority: WO
Inventors: Christian Haastrup MERRILD; Morten Opstrup ANDERSEN; Flemming Jensen
Original assignee: Cavendish Hydrogen A/S
Priority date: 2023-04-18
Filing date: 2024-04-17
Publication date: 2024-10-24
Also published as: DK181958B1; DK202370181A1

Abstract

In an aspect, the invention relates to a multi-layered diaphragm for a high-pressure gas compressor comprising a circumferential area, wherein said multi-layered diaphragm is characterized in that it comprises a protruding part in said circumferential area.

Description

MULTI-LAYERED DIAPHRAGM FOR A HIGH-PRESSURE COMPRESSOR Field of the invention [0001] The invention relates to a multi-layered diaphragm for a high-pressure diaphragm compressor. Background of the invention [0002] In the art multi-layered diaphragms for a high-pressure diaphragm compressor are known e.g. from applicants own international patent applications with publication number WO2016184468A1 describing a high-pressure compressor and WO2022002326A1 describing a leakage system for a high-pressure compressor. Also Chinese patent application with publication number CN110529370 and Utility model with publication number CN218325217 disclose multi-layered diaphragms. [0003] One advantage in using multi-layered diaphragms in a high-pressure compressor for pressurizing hydrogen is that the gas side can be completely isolated from the hydraulic side thus avoiding e.g. oil residue in the gas. A further benefit being that the gas side diaphragm can be coated to resist hydrogen embrittlement. The oil side diaphragm can be coated for other properties and the middle diaphragm, which may be referred to as a leak detection diaphragm, can prevent mix of gas and oil in case leakage at one or both gas and oil side diaphragms. [0004] The high-pressure diaphragm compressor comprise a gas cavity provided in the upper head maybe in a gas plate of the upper head and an oil cavity provided in the lower head maybe in an oil plate of the lower head. To ensure that no gas and oil are leaking between the upper and lower heads where the multi-layered diaphragms is clamped, there is provided a seal groove in the upper and lower heads. In these seal grooves a seal is positioned which via a clamping force can provide a gas or oil-tight seal to the multi-layered diaphragm when the upper and lower compressor heads are fastened together by bolts. [0005] This way of sealing however, may lead to stress concentrations and wear of the diaphragm around the seal which again may lead to cracks in the diaphragm resulting in costly downtime and maintenance. Summary of the invention [0006] The inventors have identified the above-mentioned problem related to sealing of a high-pressure diaphragm compressor and solved this problem by the present invention as described below. [0007] In an aspect, the invention relates to a multi-layered diaphragm for a high- pressure gas compressor comprising a circumferential area, wherein said multi-layered diaphragm is characterized in that it comprises a protruding part in said circumferential area. [0008] A protruding part in the circumferential area is advantageous in that it provides a spring effect. Such spring effect has is advantageous that it has the effect that it can absorb a distance / clearance occurring between the upper and lower parts of the head of the compressor while maintaining the sealing forces / effect. Such clearance is occurring because of the repelling force occurring between these upper and lower parts due to the high reciprocating pressure from gas / oil pressure. [0009] A multi-layered diaphragm (also simply referred to as a diaphragm) having a circumferential protruding part is advantageous in that it has the effect, that no seal groove is needed in the oil or gas plate (the one towards which the protruding part is protruding). Thereby stress concentration is avoided and fatigue stress is reduced in diaphragms, which helps to increase service intervals and thereby to lower maintenance cost. Further, availability of the compressor is increased due to the reduced maintenance and longer lifetime of the diaphragm. [0010] Further, since the protruding part acts as a seal, the seal can be integrated into the diaphragm, reducing the required number of parts inside the compressor head leading to a reduction in price, time of assembly and risk of human errors during assembly of the compressor. [0011] High-pressure gas compressor (sometimes referred to simply as compressor) should be understood as a compressor capable of pressurizing a gaseous fluid to a pressure between 35MPa and 120MPa. In some embodiments, up to a pressure of 120MPa. The compressor comprises an upper head (which may comprise a gas plated) and a lower head (which may comprise an oil plate). In the upper head is a gas cavity and in the lower head is an oil cavity. The part of the diaphragm which is positioned between these cavities and the outside of the compressor head is exposed to a clamping force from the assembly of the upper and lower heads (the fastening of the upper and lower head to each other). The part of the diaphragm that is exposed to this clamping force is referred to as the circumferential area. [0012] Despite the upper and lower heads are massive and assembled with a plurality of bolts, the force from the high hydraulic pressure repels / separates slightly the upper and lower heads periodically at every compressor cycle. The diaphragm of the present invention comprises a protruding part which solves the problem of maintaining a sealed oil and / or gas chamber without the introduction of stress concentrations from seal grooves in the upper / lower heads. [0013] In an exemplary embodiment of the invention, said protruding part comprising at least an outer contract line, a middle contact line and an inner contact line. [0014] Using one or more contact lines is advantageous in that it has the effect that contact between two planes (such as two surfaces) are improved compared to contact between the two plans obtained by contact points. Thereby the sealing effect is increased / improved. Zooming in on a diaphragm (or gas / oil plate) one will discover that the surface of the diaphragm is jagged and thereby a plurality of contact points is established between the diaphragm and the seal in a known compressor. The sealing effect of a plurality of points is not as good as the sealing effect of predefined line enclosing / surrounding the compression cavity. [0015] In an exemplary embodiment of the invention, said protruding part has a convex shape. [0016] The shape (could also be referred to as geometry) of the protruding part may have various characteristics. As mentioned, it may be curved such as having a convex shape or it may have a triangular shape. In addition, it may also have a combination of straight lines and curved lines i.e. a combination of a curved and tri-or multi-angular shape. [0017] Alternatively, the protruding part may have a plurality of straight lines such as forming part of a pentagon, hexagon, etc. The importance of the proposed design is that the geometric angles are not too sharp, which has an added benefit of reducing mechanical stresses experienced by the diaphragms. [0018] In an exemplary embodiment of the invention, said inner contact line of said protruding part is located with a distance of a side part to a cavity area of said multi- layered diaphragm. [0019] A side part should be understood as part of the diaphragm which is forced in a direction opposite the force applied to the protruding part when the upper and lower heads are assembled. A side part is present on both the cavity and the outer side of the protrudin part. [0020] Spacing the inner contact line from the cavity with the distance of a side part is advantageous in that it has the effect, that the maximum (or desired) spring effect is obtained. [0021] In an exemplary embodiment of the invention, said inner contact line is located a first distance from said cavity area, wherein said first distance is between 0,5cm and 5,5cm, preferably between 1cm and 4,5cm most preferably between 1,5cm and 4cm. [0022] Having a distance between 0,5cm and 1cm from the cavity area to the inner contact line is advantageous in that then the optimal trade off between stress of the diaphragm provided by contact between diaphragm and upper / lower head and the spring effect provided by the size of the side part. Longer side parts are desired to increase the spring effect but shorter side parts are desired to reduce force acting on the compressor head. [0023] In an exemplary embodiment of the invention, said outer contact line is located a second distance from said inner contact line, wherein said second distance is between 0,1cm and 2cm, preferably between 0,1cm and 1,5cm most preferably between 0,1cm and 1cm. [0024] A distance between 0,1cm and 1cm such as between 0,1cm and 0,5cm such as 0,25cm is an example of the width of the protrusion part. In this example, the thickness of the diaphragm (the oil diaphragm) is in a range of 0,25mm to 2,5mm [0025] The second distance may also be referred to as the width of the protruding part. [0026] In an exemplary embodiment of the invention, said first distance is larger than said second distance. [0027] This is advantageous in that hereby it is ensured that there is sufficient diaphragm material on the outside of the protruding part (between the outer contact line and the edge of the membrane) for the protruding part to be able provide the spring effect. [0028] In an exemplary embodiment of the invention, said protruding part has a height defined by a third distance, said third distance is measured between a line extending between said outer contact line and said inner contact line and said middle contact line, wherein said third distance is measured perpendicular to said line, wherein said third distance is between is between 0,01cm and 2cm, preferably between 0,05cm and 1cm most preferably between 0,1cm and 0,5cm. [0029] A height between 0,1cm and 0,5cm is advantageous in that this is sufficient high of the protrusion part to provide the desired spring effect. [0030] In an exemplary embodiment of the invention, said second distance is larger than said third distance. [0031] In an exemplary embodiment of the invention, said multi-layered diaphragm comprises an oil diaphragm, a gas diaphragm and a leak diaphragm, wherein said protrusion part is provided in said oil diaphragm. [0032] Providing the protruding part in the oil diaphragm is advantageous in that no seal groove is provided in the oil plate and thus no groove edges is provided which lead to stress and wear in said diaphragm. [0033] In an exemplary embodiment of the invention, said oil diaphragm, said gas diaphragm and said leak diaphragm is made of a material comprised by the list of materials comprising: spring steel, alloys and composite. [0034] These materials are advantageous in that they have a high yield point and high fatigue resistance and thereby allow operation of the same diaphragm for longer time compare to diaphragms made of other materials such as structural steels, aluminium alloys or polymers. [0035] Composite materials are advantageous in that they can be designed according to specific requirements. [0036] In an exemplary embodiment of the invention, said protrusion part is provided in said gas diaphragm. [0037] In an exemplary embodiment of the invention, said oil diaphragm, a gas diaphragm and a leak diaphragm are all having a thickness between 0,1mm and 10mm, preferably between 0,15mm and 0,8mm, most preferably between 0,2mm and 0,6mm. [0038] It has been found that a thickness of a single diaphragm e.g. between 0,25mm and 0,5mm provides a good balance between strength and flexibility to enable a diaphragm to run for more than 10mil cycles. The thickness of the diaphragm including three individual diaphragms may thus be in the range of 0,75mm and 1,5mm. It should be noted that the diaphragms may be of different thicknesses. [0039] In an exemplary embodiment of the invention, said multi-layered diaphragm is oblong when seen in a top view. [0040] In an exemplary embodiment of the invention, a circumferential area of said oil diaphragm is at least partly coated with a sealing coating. [0041] In an exemplary embodiment of the invention, a protrusion part area of said oil diaphragm is coated with said sealing coating. [0042] Providing a sealing coating is advantageous in that it has the effect, that it is smoothening the surface of the diaphragm. When zooming in on the surface of the diaphragm one will note that it is not completely planer i.e. a plurality of peaks of diaphragm material will be seen. When the diaphragm surface between and over these peaks is coated with a soft coating such as a polymer material, the surface is smoothened leading to a more tight assembly / connection between the diaphragm and in this case the oil diaphragm. [0043] In an exemplary embodiment of the invention, said protrusion part area extend at least 1,5cm, preferably at least 1cm, most preferably at least 0,5cm to both sides of said middle connection line. [0044] By referring to both sides of the middle connection line a reference is made to a distance from the middle connection line towards the side of the outer connection line and a distance from the middle connection line towards the side of the inner connection line. Hence, a distance of e.g. 2cm from the middle line towards the outer connection line and a distance of e.g. 2cm from the middle line towards the inner connection line i.e. in this example a total of 4cm is coated with a polymer coating. [0045] It should be mentioned that the entire circumferential area may be coated with a polymer or the entire circumferential area from the outer edge to a predetermined distance from where the cavity starts. [0046] In an exemplary embodiment of the invention, a cavity area of said oil diaphragm is coated with a metal coating. [0047] A coating of the cavity area of an oil diaphragm (or main part hereof) is advantageous in that it has the effect, that friction is reduced between oil cavity plate and diaphragm leading to a reduced wear of the diaphragm. [0048] In an exemplary embodiment of the invention, a circumferential area of said gas diaphragm is at least partly coated with a polymer coating. [0049] In an exemplary embodiment of the invention, a protrusion part area of said gas diaphragm is coated with a polymer coating. [0050] In an exemplary embodiment of the invention, said protrusion part area extend at least 1,5cm, preferably at least 1cm, most preferably at least 0,5cm to both sides of said middle center line. [0051] A coating of the cavity area of the gas diaphragm (or main part hereof) is advantageous in that then the gas diaphragm is more resistant to hydrogen and the wear of the diaphragm caused by the hydrogen. [0052] In an exemplary embodiment of the invention, said multi-layered diaphragm comprises an oil diaphragm comprising an oil protruding part and a gas diaphragm comprising a gas protruding part. [0053] In an exemplary embodiment of the invention, said gas protruding part extend in a direction away from the direction of which said oil protruding part extend. [0054] This is advantageous in that it has the effect, that no seal grooves are needed in the oil or in the gas plates (at least for sealing gas / oil). [0055] In an exemplary embodiment of the invention, said oil protruding part and said gas protruding part are overlapping. [0056] Overlapping, including a complete overlapping, of the oil and gas protruding parts is advantageous in that it has the effect that the spring effect is increased up to maximum a double effect. Thereby, the protruding parts together are able to absorb a larger movement of the upper and lower heads during a compression cycle. [0057] In an exemplary embodiment of the invention, said oil protruding part is located closer to said cavity areas than said gas protruding part. [0058] Having the first oil protruding part closest to the cavity areas (in the plan of a relaxed diaphragm) is advantageous in that it has the effect that stress related to bending of the oil diaphragm is reduced leading to a reduced wear on the oil diaphragm. The distance between the cavity area and the first gas protruding part may be 0,5cm, 1cm, 1,5cm or 2cm or therebetween. [0059] In an exemplary embodiment of the invention, said oil diaphragm in addition to said oil protruding part also comprises a leakage oil protruding part. [0060] In an exemplary embodiment of the invention, said gas diaphragm in addition to said first gas protruding part also comprises a leakage gas protruding part. [0061] A leakage gas / oil protruding part is advantageous in that it facilitates a seal for a leakage detection system. The leakage detection system comprises grooves in the oil and / or gas plates. On the outer side i.e. between the outer edge of the oil / gas head and the first oil / gas protruding parts, these leakage detection system protruding parts are positioned. [0062] Having both a gas / oil and a leakage gas / leakage oil protruding part is advantageous in that it has the effect, that no seal grooves are needed in the oil and in the gas plates. [0063] In an exemplary embodiment of the invention, said high-pressure gas compressor comprises an oil plate in which an oil cavity is provided and a gas plate in which a gas cavity is provided, wherein the surface of a circumferential area of said oil plate and / or of said gas plate is plane. [0064] A plane surface is advantageous in that it has the effect that no grooves are needed in these circumferential areas. Thereby a manufacturing process is removed and component are superfluous leading to faster assembling of the compressor and a cheaper compressor. The drawings [0065] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. The drawings illustrate embodiment of the invention and elements of different drawings can be combined within the scope of the invention: Fig. 1 illustrates a high-pressure compressor, Fig. 2 illustrates a gas / oil diaphragm in a top view, Fig.3 illustrates a multi-layered diaphragm comprising a protruding part in a top view, Fig. 4 illustrates the protruding part of one diaphragm in a perspective view, Fig. 5 illustrates the protruding part of one diaphragm in a side view, Fig. 6 illustrates two diaphragms each with a protruding part in a side view, and Fig. 7a and 7b illustrates forces acting on the two diaphragms. Detailed description [0066] The present invention is described in view of exemplary embodiments only intended to illustrate the principles and implementation of the present invention. The skilled person will be able to provide several embodiments within the scope of the claims. [0067] Fig. 1 illustrates an example of a high-pressure diaphragm compressor 1 in which a multi-layered diaphragm 2 according to the present invention is used. The high-pressure diaphragm compressor 1 is illustrated in a side view and may be a hydrogen gas compressor (sometimes simply referred to as a compressor). A gas cavity also referred to as a gas chamber 3 is illustrated in an upper head / gas plate 4 and an oil cavity also referred to as oil chamber 5 is illustrated in a lower head / oil plate 6. The inner walls of these chambers 3, 5 may be equipped with tracks or recesses which are used to guide hydraulic fluid (also referred to simply as oil) and gas respectively in / along predetermined path / direction. The two chambers 3, 5 are separated by the multi-layered diaphragm 2 which is made of several sheets of metal or alloy. Alternatively, the diaphragm or a sheet hereof can be made of a composite material. [0068] The design of the oil and gas chambers 3, 5 and of channels leading oil and gas to and from these chambers 3, 5 together allows the diaphragm 2 to bend and thereby, due to difference in pressure, gas flow from a gas source into the gas chamber 3 via the inlet. When the diaphragm is moving towards the gas chamber, gas pressure increases and when above the discharge pressure leaves the outlet 8. Non-illustrated pressure and temperature sensors and valves may be used by a controller 9 to control the gas flow and operation of the compressor 1. [0069] Accordingly, by the compressor 1 it is possible to pressurize gas according to a compression ratio of e.g. 1:2 i.e. from a pressure in a supply storage of 300bar to a pressure delivered to a receiving vessel of 600bar. Thus, if higher pressure is needed, a second compression stage may be used to increase the 600bar to 1200bar (if the second stage also has a ratio of 1:2). Hence, the compressor 1 of the present invention is a high-pressure compressor in that it can pressurize a gas such as a hydrogen gas to a pressure of 1000bar or even higher as indicated. [0070] Such high pressure is facilitated by a reciprocating movement of a piston 10 moving in a cylinder 11. This movement is facilitated by a crankshaft mechanically connected to the piston 10. The piston 10 then forces oil from the cylinder into the oil chamber 5. As the piston continuous towards its top dead center, it increases the pressure of the oil in the chamber 5. Thereby, the diaphragm 1 is pushed towards the gas chamber 3 and thereby compresses the gas comprised therein to a certain pressure until a discharge valve in the outlet 8 opens. [0071] The oil is comprised in a close circuit which could be said to start in a hydraulic fluid reservoir 12. If oil is needed in the oil chamber 5, oil from this reservoir 12 may be guide to the oil chamber 5 via a first conduit 13a. A hydraulic fluid adjustment assembly 14 together with valves 15a, 15b may be controlling the oil flow to and from the oil chamber 5. The valve 15b positioned in a second conduit 13b may only be used to prevent failure in case the pressure in the oil chamber 5 is too high and thereby risking damaging e.g. the diaphragm. [0072] In an embodiment, the oil adjustment assembly 14 may be controlled by a PID regulator which may be comprised by the controller 9. The adjustment assembly 14 may comprises a pressure booster comprising a first low-pressure end and a second high-pressure end. The second end is a high-pressure end fluidly connected to the hydraulic chamber 5 via the conduit 13a. The first end is a low-pressure end fluidly connected to a hydraulic fluid reservoir 12. [0073] A movable member comprises a high-pressure part and a low-pressure part may be comprised by the booster. These parts may be piston like parts moving in cylinder like volumes. Hence, by knowledge of these cylinder-like volumes, specifically the high-pressure part, knowledge of volume of hydraulic fluid injected into the chamber 5 by a certain displacement of the movable member is available. [0074] Between the booster and the reservoir 12 a valve referred to as first valve is positioned. This first valve is positioned at this location to control flow from the booster to the reservoir 12 in case hydraulic fluid is to be removed from the hydraulic chamber 5. Further, the first valve has to control flow of hydraulic fluid from a pump to the low-pressure part of the booster 21 in case hydraulic fluid has to be injected to the hydraulic chamber 5. Hence, by adding hydraulic fluid with a low pressure the movable member is pushed towards the second end and thereby hydraulic fluid with high-pressure is pushed towards the chamber 5. [0075] The adjustment assembly 14 may further comprise a second valve which is connected between the booster and the chamber 5. The main purpose of the second valve is to control flow of hydraulic fluid between the fluid reservoir 12 and the high- pressure part (between a high-pressure end of the movable member and the second end) of the booster. [0076] A pump such as the pump may be connected between the second valve and the reservoir 12 which, when the second valve is open may facilitate flow of hydraulic fluid into the high-pressure part. [0077] The oil flow is controlled by the controller 9 based on input from one or more sensors such as one or more hydraulic fluid pressure sensors or gas sensors. These sensors are not illustrated but may be located so as to be able to measure gas pressure or oil pressure in the chambers 3, 5 or derive these pressures from measurements made elsewhere. [0078] The oil pressure is typically equal to the gas discharge pressure when the gas discharge valve opens in the gas discharge 18. Hence, the oil pressure is regulated according to a required discharge pressure of the compressor and thus, the oil level (pressure and / or volume) can be reduced when requirements to gas discharge pressure are low to reduce wear of diaphragm, and elevated when discharge pressure needs to be higher. [0079] Fig.2 illustrates a diaphragm 2 according to an embodiment of the invention. The illustrated diaphragm 2 serves to define parts of the diaphragm which are referred to by the same terminology on both the oil diaphragm 2a and the gas diaphragm 2b. The diaphragm 2 is illustrated as two half circles. This is to indicate, that the oil / gas chambers 3, 5 covered by the diaphragm 2 may not necessarily be circular. The chambers may have an oblong shape such as an elliptic shape including super elliptic shapes which can be calculated by the mathematical formula for a super ellipse as described in applicants own publication WO2016184468A1. [0080] Hence, both the oil diaphragm 2a and the gas diaphragm 2b may have what is referred to as a cavity area denoted 22a and 22b respectively, a circumferential area denoted 21a and 21b respectively and a protrusion part area denoted 23a and 23b respectively. These areas are also indicated at fig. 1 with reference to the upper and lower heads 4, 6. Hence, the part clamped between the upper and lower heads is referred to as the circumferential areas 21. The middle part of the circumferential areas 21 is referred to as the protrusion part area 23 and the part not clamped between the upper and lower head is referred to as cavity area 22. It should be noted, that the protrusion part 16 is preferably the same thickness as the rest of the multi-layered or as at least one of the layers of the multi-layered diaphragm. Accordingly, the protrusion is defining a duct when not clamped between the compressor heads i.e. when it is in its resting position. In this way, the advantages of its flexibility described in this document is provided. Advantage that are not available if the protruding part were solid like a gasket i.e. if the above-mentioned duct were solid. [0081] In an embodiment, the circumferential area 21 extend from the outer periphery 20 and inwards so as to define a width which is below 10cm such as below 8,5cm such as 7,5cm. The circumferential area 21 should provide space for bolts clamping the upper and lower heads together, leakage grooves for detection of leakage of gas and / or oil, etc. [0082] In an embodiment, the width of the protrusion part area 23 is smaller in width of the circumferential area 21. The width of the protrusion part area 23 is below 9cm such as below 7,5 cm such as below 5,5cm. [0083] In an embodiment, the width of the cavity area 22 depends on the design i.e. if the cavities 3, 5 are circular or elongated. If they are elongated the width depends on if the width is measured in a side view or end view. Hence, as a specific example could be mentioned, that an elongated cavity may have a length of between 25cm and 30cm such as 27cm and a width between 12cm and 17cm such as 15cm. [0084] For completeness with respect to dimensions, the height of the oil and gas chambers measured from their inner wall farthest away from the diaphragm, when the diaphragm is in a rest position, to the resting diaphragm is measured in millimetres such as between 1mm and 5mm in an embodiment. [0085] Fig.3 illustrates a multi-layered diaphragm 2 of the present invention in a top view. A circumferential protruding part 16 is illustrated which is defined by an inner contact line 19, an outer contact line 17 and a middle contact line 18. As mentioned, a diaphragm having such protruding part 16 eliminates the need for a seal groove and seal in the upper head and / or in the lower head. A seal according to the present invention may be provided on one side of the diaphragm whereas on the other side of the diaphragm conventional sealing is implemented. [0086] This is because, the protruding part 16 acts as a seal when clamped between the upper and lower heads 4, 6. The protruding part 16 comprises a spheric part protruding from the rest of the diaphragm in its relaxed state. This protrusion is in the figures illustrated as a half circle. It should however be noted that the protruding part may be less than half of a circle. Further, it should be mentioned that the protrusion may have other shapes than a spheric shape as illustrated in the figures. Other shapes such as pentagon or hexagon as example may also be used according to the same principles as those described in relation to the illustrated spheric shape. [0087] When clamped between the upper and lower head 4, 6 the protrusion / half circle of the protrusion part 16 is deformed. Hence, if the diaphragm illustrated in fig. 3 is the gas diaphragm, then when clamped, at least the contact lines 17, 18 and 19 of the protruding part 16 is forces to be in contact with the leakage diaphragm and the upper head. More specific, the middle contact line 18 is in contact with the upper head and the inner and outer contact lines 17 and 19 are in contact with the leakage diaphragm. [0088] Because of the deformation, the protrusion having its top point in the middle contact line 18 is able to, to some extent, flex towards its relaxed position when the upper and lower head is forced away from each other due to the high pressure in the oil chamber 5. In this way a seal is established without a seal groove and seal. [0089] One way of providing a protruding part 16 as illustrated is by punching it into the diaphragm. It should be mentioned, that one, two or all diaphragms of the multi- layered diaphragm may have a protruding part 16. [0090] The diaphragms may be of a type of steel which has high resistance to repetitive movements such as those of a diaphragm in a compressor. Spring steels is an example of a material that has some of the properties which is desired for a diaphragm of a high-pressure compressor. These properties include high yield stress and high fatigue strength. [0091] As mentioned, to improve the properties of the surface of the diaphragms 2a- 2c and inner surface of the oil and gas chambers may be coated. Such coating may be applied by physical vapor deposition or dipping and the coating may be an amorphous carbon coating. [0092] The coating on the gas diaphragm should be resistant to hydrogen embrittlement. Coatings in the interface of the diaphragms should ensure cold welding does not occur. [0093] The entire diaphragm, including the protrusion part area 23, may be coated as described above. In addition, the protrusion parts 16a, 16b may be coated with a polymer to increase the sealing effect of the protrusion 16. Such polymer coater may be applied any means of adding adhesives or coatings to a surface such as, brushing, spraying, screen printing or dipping. Such polymer / elastomer coating may comprise, but are not limited to polyethylene, polytetrafluoroethylene, polyepoxide, polyester, polyether, polyvinyle, polystyrene, polypropylene, nylon, PUR (PUR; PolyUrethane), NBR (NBR; Nitrile Buradiene Rubber), etc. [0094] Fig. 4 illustrates a circumferential area 21 of a gas or oil diaphragm comprising one protruding part 16. This protruding part 16 has a width defined by the distance d2 which is the length of the line L between the inner and outer contact lines 17, 19. In an embodiment this length is between 1,5mm and 3,5mm such as 2,5mm. The width should be sufficiently large to facilitate the spring effect, but not too large so that the protrusion is collapsing. In other words, the elastic deformation should be maintained, if excessive plastic deformation occurs the sealing effect of the protruding part 16 when the upper and lower heads are moving away from each other cease to exists. Some plastic deformation will most likely be occurring, but excessive localized plastic deformation may change the elastic behaviour of the protrusion/diaphragm and is thus not appreciated. [0095] Also, a distance d1 is illustrated which is measured between the inner contact line 19 and the cavity area 22 of the diaphragm. The size of this distance d1 should be sufficiently large to facilitate the elastic deformation associated with the protruding part and side parts. Hence, when a clamping force from the two heads are pushing the middle contact line 18 in a direction towards a line L, a counteracting force will act from parts of the diaphragm on both sides of the protrusion part. More specifically from the side part on the outer side of the outer contact line 20 and from the side part on the inner side of the inner contact line 19. This counteracting force will have a direction opposite the clamping force pushing on the middle contact line. Together this force and counteracting force provides the elastic deformation of the protruding part 16. [0096] Therefore, to be able to facilitate this, the outer contact line 17 of the protrusion part 16 should not be too close to the outer periphery 20 ideally more than 0,5cm away. Similarly, the inner contact line 19 of the protrusion part 16 should not be closer to the cavity area 22 than 0,5cm. [0097] Fig. 5 illustrates a diaphragm 2 in a side view. The line L between inner and outer contract line 17, 19 is perpendicular to a distance d3 between the line L and the middle contact line 18. This distance d3 defines the height of the protrusion part 16 which in embodiments is between 0,01-0,03cm. [0098] A contact line as those provided by the protruding parts of the present invention is advantageous in that such “line” is not "disturbed” by local errors. It could be said that the “line” is sealing in the macro scale and the polymer coating is sealing in the micro-scale. [0099] In relation to fig. 1-5 one diaphragm or one sheet of a multi-layered diaphragm has been disclosed. It should be understood that this description applies to both a protrusion part 16 on a gas diaphragm 2b and on an oil diaphragm 2a. Hence, in an embodiment only the gas diaphragm and / or the oil diaphragm and / or the leak diaphragm 2c comprise a protruding part 16. [0100] No matter the number of protrusion parts on which diaphragm it has been found that it is advantageous if the protrusion parts is located on the half of the circumferential part 21 which is towards cavity area 22. This is of course because then space is provided to holes for bolts clamping the upper and lower head, but it is also because the pressurized area is minimized and thus the forces separating the heads. [0101] In the embodiment where both the gas and oil diaphragms comprise a protrusion part, the protrusion part of the oil diaphragm may be closest to the cavity area to reduce wear of the diaphragm at the transition area between circumferential area and cavity area. This is because the pressure is highest at in the oil cavity and thereby the pressure from the oil side is higher than the pressure from the gas side. [0102] As indicated, both of the gas and oil diaphragms 2a, 2b may comprise a protruding part 16a, 16b. An example hereof is illustrated on fig. 6. In fig. 6 the two protruding parts 16a, 16b are positioned in the protruding part area 23 i.e. on both sides of the illustrated protruding part area 23 what is referred to as circumferential area 21 is found. [0103] As illustrated, the two protrusion part 16a, 16b are displaces so that they are not overlapping. This is to illustrate the above i.e. that the protruding part 16a of the oil diaphragm 2a can be positioned closest to the cavity area 22 if the two protrusion parts 16a, 16b are not aligned. [0104] In an alternative embodiment, the two protrusions 16a, 1b are aligned i.e. in a vertical plan, the inner, middle and outer contact lines are placed above each other. This is advantageous in that the sum of flex / elastic deformation provided by the two together provide a higher flexibility to the multi-layered diaphragm than when they are placed as illustrated in fig.6. This allows the multi-layered diaphragm to “absorb”, by the flexing of the two protruding parts, a larger distance between the upper and lower heads caused by the high pressure of in the oil chamber. [0105] Fig. 7a and 7b serves to illustrate the forces applied to the diaphragms 2a-2c from the upper and lower heads 4, 6. The diaphragms 2a-2c illustrated between upper and lower heads 4, 6 on fig. 7a, 7b could be those illustrated alone on fig. 6. It should be mentioned that the sizes of the illustrated protruding parts are much larger compared to the upper and lower head than in the real world. [0106] The upper and lower heads 4, 6 are clamped together by not illustrated bolts at the outer periphery thus, around the circumference, the diaphragm 2 can comprise holes through which the bolts can go through. Accordingly, a bolt area 24 exists between the outer side of the protruding part 16a and the outer periphery. The size of the bolt area 24 should by sufficiently large to allow a bolt hole and the outer side part 25 associated with the protruding part 16a of the oil diaphragm 2b (in this particular embodiment). [0107] The side part 25 is an area on both the outer and center side of the protruding part. At fig. 7a side parts 25 are illustrated as a distance from the protruding part with small arrows that decrease in size with distance from the protruding part. At fig.7b the side parts 25 are illustrated with line sections denoted 25. The effect of the side part is that when a force is applied from the upper / lower head to the protruding part, a counter acting force is applied from the side parts as consequence of the deformation of the protruding part. The mentioned forces are illustrated as arrows on fig. 7a. Accordingly, it is the side parts 25 together with the protruding part 16 that creates the desired spring effect when the clamping force is applied by the upper and lower heads. [0108] Hence, the side parts 25 belongs to the protruding part area 23. It should be mentioned that it is not easy to define a sharp line between which part of the circumferential part 21 that also belongs to what is referred to as the protruding part area 23. In fact, it may be possible to measure the counter acting force even at the outer periphery 20 i.e. at the bolt area 24. [0109] In fig. 7b the upper and lower heads 4, 6 are illustrated as providing a clamping force to the protruding parts 16. The diaphragms 2a, 2b, 2c are in fig. 7b illustrated as thick lines. Hence, the thick lines of fig. 7b illustrates an example where a clamping force is applied to the diaphragms 2a, 2b (arrows from upper and lower heads of fig. 7a). This clamping force is forcing the protruding parts, starting at the middle contact line, in the direction of the force. This leads to a force at the side parts 25 which “lifts” the sides parts 25 towards the upper or lower head respectively. In this way, the diaphragms 2a, 2b are elastically deformed meaning that movement between upper and lower heads lead to a deformation of the diaphragms 2a, 2b towards their relaxed state (illustrated in fig. 6). [0110] Hence, when clamped between the upper and lower heads 4, 6 side contact points 26a in addition to the already existing contact points 26 are established between the diaphragms 2a, 2b and the upper / lower head respectively. At point 26a and away from the protrusion, the forces will again be in the direction of the clamping force from the upper / lower head respectively. Thus, the diaphragm of the present invention provides counter acting forces at least at the side parts 25 when clamped between the upper and lower heads. [0111] As mentioned, it is possible to align the middle contact lines of the protruding parts above each other i.e. with the same distance to the outer periphery. As can be imagined from the thick lines of fig. 7b if located above each other, the distance that can be absorbed by the protruding parts is increased (compared to the location of the protruding parts illustrated in fig. 7a or 7b). [0112] In figures 6 and 7 the protruding part 16b of the gas diaphragm is illustrated closer to the cavity area 22 than the protruding part 16a of the oil diaphragm. It should however be noted that it may be preferred or at least possible to locate the protrusion part 16a of the oil diaphragm closest to the cavity area 22 if not the location of the two protrusions 16a, 16b are aligned on top of each other. With this said, the protrusion part 16b of the gas diaphragm may alternatively be located closest to the cavity area 22. [0113] From the above it is now clear that the invention relates to a diaphragm for a high-pressure gas compressor, the diaphragm comprises a protruding part acting as a seal. Further, it is clear that both a gas and an oil diaphragm of a multi-layered diaphragm may comprise such protruding part. [0114] In fact, it should be noted, that also the leakage diaphragm may comprise such protruding part and that each diaphragm may include more than one such protruding part. [0115] The advantage of a diaphragm having a protruding part is that a spring effect is provided that is able to absorb the clearance between the upper and lower heads periodically in each cycle. Therefore, no seal grove with associated seal is needed in the upper / lower head. This reduces stress on the diaphragm and thus is leading to a longer lifetime of the diaphragm, less maintenance and thus an increased availability of the compressor. [0116] The invention has been exemplified above with the purpose of illustration rather than limitation with reference to specific embodiments. Details of specific embodiment have been provided in order to understand the aim of the invention. Please note, that detailed descriptions of well-known systems, devices, circuits, and methods have been omitted so as to not obscure the description of the invention with unnecessary details.

List 1. High-pressure diaphragm compressor 2. Multi-layered diaphragm a. Oil diaphragm b. Gas diaphragm c. Leakage diaphragm 3. Gas chamber 4. Upper head / gas plate 5. Oil chamber 6. Lowe head / oil plate 7. Gas inlet 8. Gas outlet 9. Controller 10. Piston 11. Cylinder 12. Oil reservoir 13. Oil conduits 14. Oil adjustment assembly 15. Valves 16. Protruding part a. Protruding part of oil diaphragm b. Protruding part of gas diaphragm a’. Leakage protruding part of oil diaphragm b’. Leakage protruding part of gas diaphragm 17. Outer contact line 18. Middle contact line 19. Inner contact line 20. Outer periphery 21. Circumferential area a. Circumferential area of oil diaphragm b. Circumferential area of gas diaphragm 22.Cavity area a. Cavity area of oil diaphragm b. Cavity area of gas diaphragm 23. Protrusion part area a. Protrusion part area of oil diaphragm b. Protrusion part area of gas diaphragm 24. Bolt area 25. Side part 26. Contact points a. Side contact points d1. First distance d2. Second distance d3. Third distance L. Line

Claims

Patent claims 1. A multi-layered diaphragm (2) for a high-pressure gas compressor comprising a circumferential area (21), wherein said multi-layered diaphragm (2) is characterized in that it comprises a protruding part (16) in said circumferential area (21).

2. A multi-layered diaphragm (2) according to claim 1, wherein said protruding part (16) comprising at least an outer contract line (17), a middle contact line (18) and an inner contact line (19).

3. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said protruding part (16) has a convex shape.

4. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said inner contact line (19) of said protruding part (16) is located with a distance of a side part to a cavity area (22) of said multi-layered diaphragm (2).

5. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said inner contact line (19) is located a first distance (d1) from said cavity area (22), wherein said first distance (d1) is between 0,5cm and 5,5cm, preferably between 1cm and 4,5cm most preferably between 1,5cm and 4cm.

6. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said outer contact line (17) is located a second distance (d2) from said inner contact line (19), wherein said second distance (d2) is between 0,1cm and 2cm, preferably between 0,1cm and 1,5cm most preferably between 0,1cm and 1cm.

7. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said first distance (d1) is larger than said second distance (d2).

8. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said protruding part (16) has a height defined by a third distance (d3), said third distance (d3) is measured between a line (L) extending between said outer contact line (17) and said inner contact line (19) and said middle contact line (18), wherein said third distance (d3) is measured perpendicular to said line (L), wherein said third distance is between is between 0,01cm and 2cm, preferably between 0,05cm and 1cm most preferably between 0,1cm and 0,5cm.

9. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said second distance (d2) is larger than said third distance (d3).

10. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said multi-layered diaphragm (2) comprises an oil diaphragm (2a), a gas diaphragm (2b) and a leak diaphragm (2c), wherein said protrusion part (16) is provided in said oil diaphragm (1a).

11. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said oil diaphragm (2a), said gas diaphragm (2b) and said leak diaphragm (2c) is made of a material comprised by the list of materials comprising: spring steel, alloys and composite.

12. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said protrusion part (16) is provided in said gas diaphragm (2b)

13. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said oil diaphragm (2a), a gas diaphragm (2b) and a leak diaphragm (2c) are all having a thickness between 0,1mm and 10mm, preferably between 0,15mm and 0,8mm, most preferably between 0,2mm and 0,6mm.

14. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said multi-layered diaphragm (1) is oblong when seen in a top view.

15. A multi-layered diaphragm (2) according to any of the preceding claims, wherein a circumferential area (21a) of said oil diaphragm (2a) is at least partly coated with a sealing coating.

16. A multi-layered diaphragm (2) according to any of the preceding claims, wherein a protrusion part area (23a) of said oil diaphragm (2a) is coated with said sealing coating.

17. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said protrusion part area (23a) extend at least 1,5cm, preferably at least 1cm, most preferably at least 0,5cm to both sides of said middle connection line (18).

18. A multi-layered diaphragm (2) according to any of the preceding claims, wherein a cavity area (22a) of said oil diaphragm (2a) is coated with a metal coating.

19. A multi-layered diaphragm (2) according to any of the preceding claims, wherein a circumferential area (21b) of said gas diaphragm (2b) is at least partly coated with a polymer coating.

20. A multi-layered diaphragm (2) according to any of the preceding claims, wherein a protrusion part area (23b) of said gas diaphragm (2b) is coated with a polymer coating.

21. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said protrusion part area (23a) extend at least 1,5cm, preferably at least 1cm, most preferably at least 0,5cm to both sides of said middle center line (18).

22. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said multi-layered diaphragm (2) comprises an oil diaphragm (2a) comprising an oil protruding part (16a) and a gas diaphragm (2b) comprising a gas protruding part (16b).

23. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said gas protruding part (16b) extend in a direction away from the direction of which said oil protruding part (16a) extend.

24. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said oil protruding part (16a) and said gas protruding part (16b) are overlapping.

25. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said oil protruding part (16a) is located closer to said cavity areas (22a, 22b) than said gas protruding part (16b)

26. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said oil diaphragm (2a) in addition to said oil protruding part (16a) also comprises a leakage oil protruding part (16a’).

27. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said gas diaphragm (2b) in addition to said first gas protruding part (16b) also comprises a leakage gas protruding part (16b’).

28. A multi-layered diaphragm (2) according to any of the preceding claims, wherein said high-pressure gas compressor comprises an oil plate in which an oil cavity is provided and a gas plate in which a gas cavity is provided, wherein the surface of a circumferential area of said oil plate (21a) and / or of said gas plate (21b) is plane.