EP2545312A1

EP2545312A1 - Valve for a gas storage

Info

Publication number: EP2545312A1
Application number: EP11775800A
Authority: EP
Inventors: Erwin Enzenhofer; Alexander Sieberer
Original assignee: DCES DynamicComponents KG
Current assignee: DCES DynamicComponents KG
Priority date: 2010-12-17
Filing date: 2011-10-26
Publication date: 2013-01-16
Also published as: WO2012079823A8; WO2012079823A1

Abstract

The present invention relates to a valve (100) for a gas storage (200). The valve (100) comprises a valve seat (110) and a valve cap (120). The valve seat (110) comprises a duct (111) which has a centre axis (115) and through which a gaseous medium is flowable and an edge (112) which surrounds the duct (111). The valve cap (120) is mounted pivotable at the edge (112) in such a way that it is pivotably around the pivot axis (121). The pivot axis (121) is spaced apart from the centre axis (115).

Description

Valve for a gas storage

Field of the invention

The present invention relates to a valve for a gas storage for storing a gaseous medium and to a gas storage for storing a gaseous medium . Moreover, the present invention relates to a method of manufacturing a valve for a gas storage for storing a gaseous medium. Furthermore, the present invention relates to a use of a gas storage as a biogas storage.

Background of the invention

Gas storages for storing gaseous medium comprise generally at its top an exterior membrane, which envelops a storage volume of the storage. In some embodiments an interior membrane is mounted that is enveloped by the exterior membrane. The inner and exterior membranes are flexible. In an inner volume which is enveloped at least partially by the interior membrane an industrial gas component, such as biogas or natural gas, is stored. The interior membrane and the exterior membrane are spaced between each other, so that an outer volume is generated. Into the outer volume, a support gas is fed for keeping a minimum support gas pressure inside the outer volume.

The interior membrane is not tightened and comprises an arbitrary, e.g. bumpy shape. The interior membrane forms a shape which is dependent on the gas pressure in the inner volume. Hence, the outer volume and as well the support gas pressure is dependent on the gas pressure of the industrial gas component in the inner volume because of the varying shape of the interior membrane. If a minimum support gas pressure is generated in the outer volume, the exterior membrane forms a stable and homogeneous shape, such as a half ball shape. A sufficiently high support gas pressure leads to a tightened and hence to a more stable exterior membrane.

If a pressure falls below minimum support gas pressure, the exterior membrane may collapse. Hence, if the exterior membrane loses its tension, the exterior membrane collapses and forms an inhomogeneous surface with e.g. folding and pockets- 1 ike curvatures. In these pockets, water, snow or other dirt particles are gathered, which leads to an undesired load onto the exterior membrane. Moreover, due to the foldings of the exterior membrane, the surface of the exterior membrane provides areas exposed to wind with inconvenient aerodynamic

characteristics. Summarizing, if the exterior membrane loses its tension, the stability of the exterior membrane and the stability of the overall storage is reduced. Moreover, the flexible exterior membrane may brake and tear if a pressure of the gaseous medium in the outer volume exceeds a certain value. Hence, pressure regulating mechanisms are needed in order to control the pressure of the gaseous medium in the outer volume. In particular, in order to prevent a loss of tension of the exterior membrane, a blower for blowing support gas into the outer volume of the gas storage is provided. Moreover, pressure regulation valves are used in order to drain off support gas or to feed support gas in the outer volume for keeping a support gas pressure in the outer volume between predetermined values of a minimum support gas pressure and a maximum support gas pressure. Additionally, further pressure regulation valves are used in order to keep the inner gas pressure in the inner volume between predetermined values of a minimum inner gas pressure and a maximum inner gas pressure.

In order to regulate the pressure inside the inner and outer volume of a gas storage, hydraulic, mechanical and hydraulic-mechanical valves are used. Under a predefined opening pressure the hydraulic valves open and gas is e.g. drained off from the inner or outer volume. In hydraulic valves, the predefined opening pressure is adjustable by amending the amount of water in a water column, for example. EP 2 208 921 Al discloses a hydraulic-mechanical excess/negative pressure prevention device. The device comprises an excess pressure valve and a negative pressure valve which are mounted into a pipe. The pipe connects the inner volume of a gas storage with the environment. In case that the gas pressure in the inner volume exceeds a predetermined maximum pressure value, the excessive pressure valve opens and gas is drained off from the pipe to the environment. In case that the gas pressure in the inner volume falls below a predetermined minimum pressure value, the negative pressure valve opens such that gas from the environment into the pipe is fed in order to increase the pressure inside the pipe and thus inside the inner volume. Hence, by providing an excessive pressure valve and a negative pressure valve, a gas pressure in the pipe and in the gas storage may be kept between a predefined high pressure limit and low pressure limit. In order to seal the respective valves, the valves are surrounded partially with a sealant liquid.

Furthermore, the amount of sealant liquid surrounding the pressure valve defines the opening pressure and thus the high pressure limit and the low pressure limit.

The adjustment of the opening characteristics of the excessive pressure valve and the negative pressure valve is time-consuming and ineffective. Moreover, due to evaporation of the liquid, the amount of liquid has to be permanently maintained. Additionally, the liquid may evaporate and then condensate at critical locations in the valve.

Object and summary of the invention

It may be an object of the present invention to provide a robust valve for a gas storage with a proper opening characteristic.

This object may be solved by a valve for a gas storage for storing a gaseous medium, by a gas storage for storing a gaseous medium and by a method of manufacturing a valve for a gas storage for storing a gaseous medium according to the independent claims.

According to a first aspect of the present invention, a valve for a gas storage for storing a gaseous medium is presented. The valve comprises a valve seat and a valve cap. The valve seat comprises a duct which has a centre axis and through which a gaseous medium is flowable and an edge which surrounds the duct. The valve cap is mounted pivotable at the edge in such a way that it is pivotably around the pivot axis, wherein the pivot axis is spaced apart from the centre axis.

In particular, the valve cap is pivotable with respect to the duct between a) a closed position for sealing the duct and b) an open position for enabling a flow of the gaseous medium through a duct.

The valve cap is mounted to the edge in such a way, that a pivot axis of the valve cap is spaced apart to the centre axis. The valve is arranged in such a way that a weight force of the valve cap and a pressure force of the gaseous medium, which acts on the valve cap, adjust a valve cap position of the valve cap between the closed position and the open position. According to a further aspect of the present invention, a gas storage for storing a gaseous medium is provided. The gas storage comprises a valve as described above.

According to a further aspect of the present invention, a method of manufacturing a valve for a gas storage for storing a gaseous medium is presented. The method comprises the forming of a valve seat with a duct which has a centre axis and through which the gaseous medium is flowable and forming the valve seat with an edge which surrounds the duct. Furthermore, the method comprises the forming of a valve cap which is mounted at the edge in such a way that it is pivotably around the pivot axis. The pivot axis is spaced apart from the centre axis.

In particular, the method comprises the mounting of the valve cap at the edge in such a way that the valve cap is pivotable with respect to the duct between

a) a closed position for sealing the duct, and

b) an open position for enabling a flow of the gaseous medium through the duct.

The valve cap is mounted to the edge in such a way that a pivot axis of the valve cap is spaced to the centre axis. The method further comprises the arranging of the valve in such a way that a weight force and a pressure force of the gaseous medium, which acts on the valve cap, adjust a valve cap position of the valve cap between the closed position and the open position. The gas storage for a gaseous medium may comprise any desired tubular shape, for example with a circular, oval, rectangular or polygonal ground area. An open top side of the storage is covered by the above-described interior and/or exterior membrane. Within the interior membrane an inner volume for storing industrial gas is formed and between the interior membrane and the exterior membrane an outer volume for storing a support gas is formed. The storage volume comprising the inner volume and the outer volume may be formed by a ground plate and/or a side wall to which the exterior membrane and the interior membrane are mounted.

The gaseous medium comprises components of industrial gas, such as natural gas or biogas, and components of support gas, such as air or inert gas. Moreover, the storage device may be a biogas storage, so that additionally to the gaseous medium biomass may be stored within the storage. In this case, the storage volume for the gaseous medium is the volume that is enveloped by the biomass, the membrane and in some cases the sidewall of the storage. The gaseous medium comprises additionally components of the support gas, such as air, which is stored in the outer volume.

The valve according to the present invention is in particular adapted for being installed to gas storages, i .e. biogas storages. The valve is designed for completely sealing the gas storage in the closed position. The valve is installable to a support gas system of a gas storage. The support gas system may comprise a blower for feeding support gas, such as air, into the outer volume such that the tension and the shape of the exterior membrane may be kept between predetermined values. If the interior membrane expands due to e.g. temperature changes inside the inner volume or due to a reduced draining of the industrial gas, e.g. biogas, out of the inner volume, the support gas has to be drained as well in order to prevent excessive pressure in the outer volume and to prevent damages to the exterior membrane. The valve may be opened for draining the support gas, if a pressure value inside the outer volume exceeds a predetermined pressure value. Moreover, the valve is installable to a pressure regulating system of the inner volume. If the gas pressure inside the inner volume exceeds a predetermined pressure, the valve may be opened for draining the industrial gas. On the other side, the valve is installable to a pressure regulating system of the inner volume in such a way that if the gas pressure inside the inner volume falls below a predetermined pressure, the valve may be opened for feeding the gas, e.g. industrial gas or environmental gas (e.g. air), into the inner volume.

The valve seat may be formed rectangular, oval, polygonal or circular, wherein the valve seat may be connected by its duct for example to a storage volume of a gas storage or to a support gas volume, such that the duct generates a fluid connection between the environment of the gas tank and the inner storage volume of the gas tank or between the environment of the gas tank and the support gas volume. The valve seat comprises the edge, at which for example a pivot joint is mounted. To the pivot joint, the valve cap may be pivotably mounted.

The valve cap may be a thin plate that comprises a shape that

corresponds for example the shape and cross section of the duct, such that in the closed position the valve cap may be in a form-fit position in order to prevent a flow of fluid through the duct. The valve cap may have in an exemplary embodiment a width or diameter between approximately 115 mm and approximately 300 mm (millimeters). Larger widths or diameters of more than 300 mm may be as well applied. The valve seat may have a respective opening width in order to form a form-fit and sealed connection with the valve cap in the closed position.

The valve cap comprises a centre of gravity, at which the weight force attacks in a generally vertical direction. The duct comprises the centre axis, wherein the location of the pivot joint at the edge is spaced apart from the centre axis. The valve may be installed in such a way, that the centre axis is non-parallel to a horizontal plane and at least a direction component of the centre axis is parallel with the direction of the weight force. Moreover, the centre axis of the duct and the pivot axis of the valve cap are orientated non-parallel, e.g. orthogonal, to each other. By the pivotable mounting of the valve cap at the edge of the valve seat, an asynchronous bearing of the valve cap at the valve seat is achieved. This is that the valve cap is not movable along a direction of a centre axis of the duct. For example, the pivot axis of the valve cap at the edge does not extend to the centre axis of the duct and/or the centre of gravity of the valve cap.

A lever arm is formed between the centre of gravity of the valve cap and a pivot axis of the valve cap around the pivot joint. Hence, the weight force attacking at the centre of gravity generates dependent on the length of the lever arm to the pivot joint a turning moment that turns the valve cap around the pivot axis. The turning moment forces the cap element to move into the closed position or the open position. Inside the duct, the gaseous medium may stream against the valve cap and generates a pressure force. The pressure force acts against the valve cap, either from the outside or the inside of the duct. Because the valve cap is pivotably mounted at the edge of the valve seat in general the force application point of the pressure force is spaced from the pivot axis by a further lever arm . Hence, the pressure force generates a further turning moment around the pivot axis which forces the valve cap to rotate between the open position and the closed position. During pivoting of the valve cap from the closed position to the open position, the lever arm between the centre of gravity of the valve cap and the pivoting axis of the valve cap decrease. The decrease of the lever arm causes a reduction of the turning moment which affects the opening characteristic of the valve. In particular, in the closed position, a long lever arm and thus a large turning moment causes a moderate and gentle opening of the valve cap, so that a low flow rate of the gaseous medium flows through the valve. Close to the (fully) open position of the valve cap, a small lever arm and thus a small turning moment causes a fast opening of the valve cap with respect to a pressure change acting on the valve cap, so that a small pressure difference leads to a rapidly changing flow rate of the gaseous medium that flows through the valve.

By the present valve according to the present invention, by simply adjusting the weight of the valve cap and/or the force application point of the weight, a desired opening characteristic of the valve is adjustable. Hence, a simple and robust valve for a gas storage is provided by the present invention which is furthermore adaptable to the need of a respective gas storage to which the valve is mounted. The lever arm between the centre of gravity of the valve cap and the pivot axis of the valve cap around the pivot joint and the weight of the valve cap may be predetermined and adjusted in such a way that the valve cap opens if a pressure difference between the environment and the inside of the duct differs for example between approximately 2 mbar to approximately 50 mbar (millibars) or more. According to a further exemplary embodiment, the valve cap comprises weight holding elements for holding a weight element for adjusting the weight force to the valve cap. If the gas pressure generates a pressure force that is higher than the weight force of the valve cap, additional weight elements may be mounted to the valve cap such that the valve is adjustable to the need of the pressure circumstances in respective gas storages.

The holding elements may be for instance clamps or screw connection elements, to which the weights may be attached.

According to a further exemplary embodiment the valve cap comprises a surface with a normal (i.e. which surface runs within a plane with a normal), wherein the weight holding element runs at least partially parallel with respect to the normal and/or at least partially nonparallel with respect to the normal. The weight holding element is formed in such a way that the weight element is located at a predefined location at the weight holding element, so that the distance of the centre of gravity of the valve cap with respect to the pivot axis is adjustable.

According to a further exemplary embodiment, the weight holding element comprises a supporting rod, such as an L-shaped supporting rod or an I-shaped supporting rod. The weight element or a plurality of weight elements is detachably mountable to the supporting rod.

By varying the amount of weight elements and additionally by varying the distance of the mounting location of the weight elements with respect to the cap element and/or with respect to the pivot axis, the centre of gravity of the valve cap may be adjusted (i.e. along a horizontal direction) closer to the pivot axis or farther away from the pivot axis. Hence, the lever arm between the centre of gravity, at which the total weight force (comprising the weight of the valve cap, the weight element and the weight holding element) acts, and the pivot axis is adjustable. Hence, the opening characteristic of the valve is adjustable. In a further exemplary embodiment, the holding elements are formed for detachably mounting the weight element to the valve cap. Hence, a flexible valve is provided, because the total weight of the cap element may be adjusted by the detachable weight elements, so that valve cap may open at different pressure conditions. Hence, the valve is installable in a variety of different gas storages and may be adapted to individual pressure conditions. Besides the higher flexibility of the valve, a more efficient manufacturing process may be achieved. For example, standardized valve caps may be produced in a high amount and individualized to the need of respective gas storages simply by adding weight elements.

According to a further exemplary embodiment, the duct comprises a first conical portion with a first cone angle and the valve cap comprises a second conical portion with a second cone angle which corresponds to the first cone angle in such a way that a form closure between the valve seat and the valve cap is achievable.

In particular, in the closed position of the valve, the valve cap and the valve seat contact each other at respective conical contact portions. In particular, the valve cap is in contact with the wall of the duct. If the wall of the duct has the first conical portion and the cap has the

corresponding second conical portion, a proper sealing between the valve cap and the valve seat is provided. The first cone angle may vary approximately less than 30° degree from the second cone angle. If the first cone angle differs more than 30° degree from the second cone angle, the form closure has to be provided e.g. by further sealing elements.

If the valve cap leaves the closed position, the flow opening of the valve between the first conical portion and the second conical portion increases more smoothly and gently in comparison to first and second portion which have no conical portions in the contact area between the valve seat and the valve cap. Hence, a smoother and slower increase of the flow rate through the duct when opening the valve cap.

According to a further exemplary embodiment, the valve cap is arranged at the valve seat in such a way that the valve cap is pivotable to the outside of the duct. In particular, the valve cap is arranged at the valve seat in such a way that

a) the direction of the weight force forces the valve cap to move in the closed position, and

b) the direction of the weight force counteracts to a force

component of a direction of the pressure force.

The direction of the weight force directs in general vertically to the ground, wherein in the present exemplary embodiment the force component of a direction of the pressure force is directed vertically in an opposed direction. Hence, by the present exemplary embodiment, the valve acts as an excessive pressure valve. If the force component of the pressure force is larger than the weight force, the valve cap pivots in the open position. Due to the exhaustion of gas through the duct, the gas pressure in the gas storage reduces. Hence, if a balance between the force component of the pressure and the weight force is generated, the valve cap remains in its position or pivots back to the closed position. The remaining position may also be a position between the closed position and the open position .

Depending on the weight of the valve cap, which may be adjusted for example by weight elements, the position of the valve cap between the closed position and the open position dependent on a predefined pressure force characteristics may be adjusted. Hence, by adjusting the weight of the valve cap it is further possible to adjust the flow rate through the duct dependent on predefined pressure values.

According to a further exemplary embodiment, the valve comprises a spring element. The valve cap is arranged at the valve seat in such a way that the valve cap is pivotable inside of the duct. The spring element is mounted to the cap element in such a way that a component of a spring force of the spring element counteracts to the weight force of the valve cap.

In particular, the spring element is mounted to the cap element in such a way that a component of a spring force of the spring element counteracts to the weight force of the cap. Further, the valve cap is arranged to the valve seat in such a way that

a) the weight force forces the valve cap to move in the open position, and

b) the weight force acts in the same direction as the force component of a direction of the pressure force.

In the present exemplary embodiment, the valve acts as a vacuum valve or a negative pressure valve. Hence, the valve cap moves from the closed position to the open position if the sum of the pressure force and the weight force is larger than the force components of the spring force that counteracts to the weight force and the pressure force. Depending on the desired pressure inside the duct, the weight of the cap element and the spring force may be adjusted. Hence, if a predefined under-pressure inside the duct with respect to the environmental pressure is given, the resulting pressure force (which is the difference between the surrounding pressure and the inner pressure in the duct) and the weight force acts in counter-direction to the spring force such that the valve cap moves into the open position. According to a further exemplary embodiment, the valve further comprises a sealing element mounted for sealing the valve cap with the valve seat in the closed position. The sealing element may be formed for example of rubber. According to a further exemplary embodiment, the valve further comprises a protective cover which is mounted to e.g. the valve seat for preventing pollutant to enter the duct.

According to a further exemplary embodiment, the valve cap and/or the valve seat comprise(s) a coating for preventing condensation. For the coating polytetrafluorethylene (PTFE), such as Teflon, may be used.

In the following, the gas storage comprising the above-described valve is described.

The gas storage may further comprise a pipe for supplying gaseous medium between the gas storage and the environment. The valve is mounted to the pipe in such a way that the duct of the valve seat of the valve is connected to the pipe such that the valve controls the flow rate of the gaseous medium through the pipe. According to a further exemplary embodiment, the gas storage further comprises a further valve which may have the same properties as the valve described above. The further valve is mounted to the pipe in such a way that the further duct of the further valve seat of the further valve is connected to the pipe for controlling the flow rate of the gaseous medium to the pipe.

The valve and the further valve may both be designed as an excessive pressure valve or both as a vacuum valve as described in the exemplary embodiments above. In these arrangements, the weight force and/or the spring force in the pairs of valves may differ, so that each valve in the pair of valve may comprise different opening characteristics.

Moreover, the valve may be designed as an excessive pressure valve and the further valve may be designed as a vacuum valve. Hence, depending on the pressure of the gaseous medium inside the pipe, the valve opens for draining gas outside the pipe or the further valve opens and gas is fed into the pipe for increasing the pressure in the pipe. By adjusting the weight of the valve cap or the further valve cap, a desired opening characteristic of the valve and the further valve may be adjusted. Hence, a simple pressure adjustment system for a gas storage is formed, without the need of complex mechanical components and without complex controlling systems. According to a further exemplary embodiment, the pipe comprises a first section which extends along a first direction. The first section comprises a top end surface which normal (i.e. which top end surface runs within a plane which normal) is parallel or substantially parallel to the first direction. The top end surface separates an inner volume of the pipe from a surrounding volume that partially surrounds the pipe, i.e. the first section of the pipe. The valve as described above is connected to the top end surface for providing a fluid connection between the inner volume and the surrounding volume.

The valve cap is aligned to the top end surface such that a normal of the surface (plane) of the valve cap is parallel with the first normal of the top end surface in the closed position.

The inner volume of the pipe describes the volume of the pipe through which gas streams with e.g. the second pressure. The surrounding volume of the pipe describes the volume that surrounds the pipe and through which the pipe streams the fluid, i.e. the gaseous medium, with the first and/or the third pressure stream.

The first direction describes a direction which is parallel to a vertical direction or which comprises an angle to the vertical direction between approximately ± 1° and approximately ±45° degree. The vertical direction describes the direction which is generally parallel with the gravity force. The horizontal direction describes the direction which is perpendicular to the vertical direction.

The top end surface describes a surface or a wall that closes an open end or a hole of the first section of the pipe. The top end surface extends along a top end plane. According to a further exemplary embodiment, the first section comprises a side surface (side wall) running within a second plane which comprises a second normal that is parallel to a second direction, wherein the side surface separates the inner volume of the pipe from the surrounding volume that surrounds the pipe, i.e. the first section of the pipe. The further valve as described above is connected to the side surface for providing a fluid connection between the inner volume and the surrounding volume, wherein the further valve cap is aligned to the side surface such that the normal of the surface of the further valve cap is parallel with the second normal in the closed position. The second direction is parallel or nonparallel with the first direction. The second direction may describe a direction which is parallel to the horizontal direction or which comprises an angle to the horizontal direction between ± 1° and ±45° degree. In particular, according to a further exemplary embodiment, the angle between the second normal of the side surface and a horizontal direction is approximately between ±5° to approximately between ±30° degree, in particular ± 10° degree.

According to a further exemplary embodiment, the gas storage comprises a further pipe which is located in the surrounding volume, wherein the further pipe connects the top end surface and the side surface in such a way that a fluid is guidable in the further pipe between the top end surface and the side surface.

It has to be noted that embodiments of the invention have been described with reference to different subject matters. In particular, some embodiments have been described with reference to apparatus type claims whereas other embodiments have been described with reference to method type claims. However, a person skilled in the art will gather from the above and the following description that, unless other notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters, in particular between features of the apparatus type claims and features of the method type claims is considered as to be disclosed with this application. Brief Description of the Drawings

The aspects defined above and further aspects of the present invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to the examples of embodiment. The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited. Fig. 1 shows a valve according to an exemplary embodiment of the present invention;

Fig. 2 illustrates a gas storage with a valve and a pipe according to an exemplary embodiment of the present invention;

Fig. 3 shows a gas storage with a valve and a further valve mounted to a pipe according to an exemplary embodiment of the present invention;

Fig.4 shows a view of a valve with conical portions according to an exemplary embodiment of the present invention;

Fig. 5 shows a diagram of an opening characteristic of a valve according to an exemplary embodiment of the present invention; Fig.6 shows a valve with an L-shaped supporting rod according to an exemplary embodiment of the present invention; and

Fig.7 shows a gas storage with a valve and a further valve mounted to a pipe according to an exemplary embodiment of the present invention, wherein a valve cap and a further valve cap have different orientations. Detailed Description

The illustrations in the drawings are schematically. It is noted that in different figures, similar or identical elements are provided with the same reference signs.

Fig. 1 shows a valve 100 for a gas storage 200 (see Fig. 2). The valve 100 comprises a valve seat 110 and a valve cap 120. The valve seat 110 comprises a duct 111 through which a gaseous medium is flowable and an edge 112 which surrounds the duct 111. The valve cap 120 is mounted pivotable at the edge 112 in such a way that the valve cap 120 is pivotable with respect to the duct 111 between

a) a closed position I for sealing the duct 111, and

b) an open position II for enabling a flow of the gaseous medium through the duct 111.

The valve cap 120 is mounted to the edge 112 in such a way that a pivot axis 121 of the valve cap 120 is spaced to the centre axis 115 of the duct 111.

The valve 100 is arranged in such a way that a weight force W of the valve cap 120 and a pressure force P of the gaseous medium which acts on the valve cap 120 adjust a valve cap position of the valve cap 120 between the closed position I and the open position II .

The duct 111 of the valve seat may comprise a circular or a rectangular cross-section, for example. The cross-section or the shape of the valve cap 120 is adapted to the cross-section of the duct 111, so that in the closed position I the duct 111 is sealed by the valve cap 120. The valve cap 120 is pivotably mounted at the edge 112 of the valve seat 110 with a pivot joint 113. The pivot joint 113 forms a pivot axis 121 around which the valve cap 120 pivots. As shown in Fig. 1, the valve cap 120 comprises a centre of gravity 122 at which the weight force W attacks. The weight force W generates a lever arm xl to the pivot axis 121 in the closed position I of the valve cap 120. Fig. 1 further shows in dotted lines a valve cap 120 in an open position II . As may be taken from the valve cap 120 in the open position II, a further lever arm x2 between the weight force F (i.e. the centre of gravity) to the pivot axis 121 is shown. Hence, the turning moment M (M =xl X W) around the pivot axis 121in the closed position I is larger than the turning moment M (M =x2 X W) of the valve cap 120 around the pivot axis 121 in the open position II.

Hence, the component of the pressure force P which acts in counter- direction to the weight force W has initially to be large enough to pivot the valve cap 120 around the pivot axis 121 in order to initiate a flow rate of the gaseous medium through the duct 111 to the environment.

In the open position II of the valve cap 120, the turning moment M is smaller than the initial turning moment M, because the lever arm x2 is smaller than the lever arm xl in the closed position I of the valve cap 120.

The pressure force P, which acts in counter-direction to the weight force W, is the result of the pressure difference between a first environmental pressure pi to a second pressure p2 in the duct 111. If the second pressure p2 in the duct 111 is larger than the environmental pressure pi, the second pressure p2 is an excess pressure. Depending on the difference of the excess pressure p2 to the environmental pressure pi and depending on the weight force W, the resulting pressure force P moves the valve cap 120 and initiate a volume flow rate of the gaseous medium from the duct 111 to the environmental pressure pi .

The weight force W counteracts to the resulting pressure P, such that the volume flow rate out of the duct 111 is a function of the weight force W and the pressure force P. Hence, in order to adapt the volume flow rate of the gaseous medium out of the duct 111 dependent on predetermined first and second pressures pi, p2, the weight force W of the valve cap 120 has to be adjusted. As shown in Fig. 1, the weight force W may be adjusted simply by fixed or detachable weight elements 123 at the valve cap 120. Complex control systems in order to control the flow rate between the duct 111 and the environment are not necessary. Moreover, in order to achieve a slowly ascending amount of the volume flow rate through the valve 100 when the valve cap 120 just left its closed position I, the valve cap 120 and the duct 111 may form

respective first and second conical portions 114, 124. As can be taken from Fig. 1, the valve seat 110 and the valve cap 120 forms contact surfaces between each other in the closed position I . In the contact surfaces, the valve seat 110 forms the first conical portion 114 and the valve cap 120 forms the second conical portion 124 that corresponds to the shape of the first conical portion 114. As can be taken from Fig. 1, in the closed position I the first conical portion 114 and the second conical portion 124 are formed in such a way that the valve seat 110 and the valve cap 120 forms a form-fit connection. Due to the first conical portion 114 and the second conical portion 124 and due to the asynchronous support of the valve cap 120 with a distance to the centre axis of the duct 111, a slower and gentle increase of the volume flow rate is generated, if the valve cap 120 just leaves its closed position I . In particular, because just after leaving the closed position I, small gaps between the respective conical portions 114, 124 are generated, such that only a small amount of gaseous medium may flow through these gaps. If the valve cap 120 rotates further to the open position II, the volume flow rate is not longer restricted by the gaps between the conical portions 114, 124, but is defined by a distance between a bottom surface of the valve cap 120 and the walls of the duct 111. Hence, when the valve cap 120 is pivoted to its open position II, the duct 111 is fully open, so that a maximum volume flow rate of the gaseous medium out of the duct 111 may be achieved.

Fig. 2 shows a valve 100 similar to the exemplary embodiment shown in Fig. 1, wherein the valve 100 is mounted to a pipe 201 of a gas storage 200.

In particular, the pipe 201 may be a part of a support gas system of a gas storage 200. The support gas system may comprise a blower for feeding support gas, such as air, into the pipe 201. The pipe 201 is connected to an outer volume between a flexible exterior membrane and an interior membrane of the gas storage 200. Hence, support gas is blown through the pipe 201 into the outer volume such that the tension and the shape of the exterior membrane may be kept between

predetermined values. If the interior membrane expands due to e.g. temperature changes inside the inner volume or due to a reduced draining of the industrial gas, e.g. biogas, out of the inner volume, the support gas has to be drained from the outer volume in order to prevent excessive pressure in the outer volume and to prevent damages to the exterior membrane. The valve 100 connected to the pipe 201 is opened for draining the support gas, if a pressure value inside the outer volume exceeds a predetermined pressure value.

In Fig. 2, the valve cap 120 is shown in the closed position I (solid line) and in its open position II (dotted lines).

Moreover, Fig. 2 shows a protective cover 202 that is mounted around the valve 100. In particular, the protective cover 202 may further comprise a filter element for filtering dirt particles, for example. The protected cover prevents the entrance of particles, such as water or dirt particles, from entering the pipe 201 through the duct 111, if the valve cap 120 is in the open position II.

Fig. 3 illustrates a gas storage 200 with a projection system for preventing an excess pressure and an under-pressure in the storage volume of the gas storage 200. In the exemplary embodiment illustrated in Fig. 3, the pipe 201 may be connected to an inner volume of the gas storage 200 in order to feed the gaseous medium into the inner volume and to drain off the gaseous medium from the inner volume. One or more valves 100 with varying opening characteristics are connectable to the pipe 201. If the gas pressure inside the inner volume exceeds a predetermined pressure, the valve 100 may be opened for draining the gaseous medium. On the other side, a further valve 300 is installable to a pressure regulating system of the inner volume in such a way that if the gas pressure inside the inner volume falls below a predetermined pressure, the further valve 300 may be opened for feeding the gaseous medium, e.g. industrial gas or environmental gas (e.g. air), into the inner volume. On the left side in Fig. 3, a valve 100 is shown which has similar properties as the valve 100 shown in Fig. 1. Hence, the valve 100 is in particular an excessive pressure valve. If the second pressure p2 in the pipe 201 exceeds a predetermined second pressure value, the pressure force P is higher than the weight force W of the valve cap 120, so that the valve cap 120 moves from its closed position I to its open position II in order to provide a volume flow rate of the gaseous medium from the pipe 201 through the duct 111 to the environment. The predetermined second pressure value p2, which causes the valve cap 120 to move in the open position II, may be adjusted by adjusting the weight elements 123. In particular, the valve cap 120 is pivotable outside of the pipe 201 for providing a gas flow outside the pipe 201 in the open position II.

As shown on the right side in Fig. 3, the further valve 300 is shown which acts as a vacuum valve or a low pressure valve. The further valve 300 comprises a further valve seat 310 with a further duct 311. Moreover, the further valve 300 comprises a further valve cap 320 that is mounted to a further edge 312 of the further valve seat 310. The further valve cap 320 is pivotable around a further pivot joint 313 mounted to the further edge 312. The further valve cap 320 is pivotable around the further pivot axis 321 in an opposite rotation direction with respect to the valve cap 120 of the valve 100. In particular, the further valve cap 320 is pivotable to the inside the pipe 201 for providing a gas flow inside the pipe 201 in the open position II.

By the further valve 300, a gaseous medium may stream through the further valve 300 inside the pipe 201, if the second pressure p2 in the pipe 201 falls under a predetermined low pressure value. Hence, the third pressure p3 in the environment of the further valve 300 may be larger than the second pressure p2 in the pipe 201. The resulting pressure P is directed in the direction of the weight force W of the further valve cap 320.

Additionally, a spring element 301 is mounted to the further valve 300, wherein the spring element 301 generates a spring force F which counteracts to the weight force W and the resulting pressure P (P=p3- p2). Hence, by the spring force F and the weight force W the

predetermined pressure value (i.e. the opening pressure) may be adjusted at which the valve cap 120 leaves its closed position I and moves to the open position II in order to provide a volume flow of the gaseous medium from the environment inside the pipe 201. In particular, the spring element 301 may comprise an adjusting unit for adjusting the spring force F, such that by simply adjusting the spring force F a desired predetermined pressure value P, at which the valve cap 120 opens, may be adjusted. Additionally or alternatively, further weight elements 323 may be attached to the further valve cap 320, such that the desired opening characteristics and the predetermined pressure value, at which the valve cap 120 moves to the open position II, is adjustable. Moreover, as can be seen in Fig. 3, both valves 100, 300 may comprise sealing elements 103 in order to improve the sealing properties of the respective valves 100, 300.

Fig. 4 shows schematically the valve 100 with conical portions 114, 124. The valve seat 110 comprises a shell surface that runs parallel with respect to a centre axis (doted lines) of the valve seat 110. The shell surface may comprise a length a along the centre axis of approximately 80mm to 120 mm (millimetres). In the end section of the shell surface along the centre line, the first conical portion 114 is formed. The surface of the first conical portion 114 forms an angle a to the shell surface of approximately 130° to 170° (degrees), preferably around 150°. The second conical portion 124 comprises a respective front face which has a run that corresponds to the first conical portion 114 in the closed position I of the valve cap 120. The first conical portion 114 and the respective second conical portion 124 may have a length b of approximately 80mm to 120 mm (millimetres). The length b may be similar to the thickness of the valve cap 120. During rotation of the valve cap 120 from the closed position I to the open position II, the edge of the valve cap 120 which faces the first conical portion 114 defines a gap between the edge of the valve cap 120 and the surface of the first conical portion 114. In comparison to portions which are parallel to the centre axis 115 of the duct 111, by using conical portions 114, 124 the edge of the of the valve cap 120 sweeps along the first conical portion 114 and the gap between the edge of the valve cap 120 and the first conical portion 114 increases more gentle.

If the valve cap 120 pivots around the pivot axis 121 of the pivot joint 113 from the closed position I to the open position II, the conical portions 114, 124 cause a smoothly increasing opening cross section between the first conical portion 114 and the second conical portion 124.

The valve seat 110 may have a diameter 0 of approximately 80 mm to 120 mm for providing a sufficient flow rate of the gaseous medium, in particular when being used in bio gas storages. Fig. 5 shows a diagram in which an opening characteristic of a valve 100 according to the present invention is illustrated. The axis of the abscissas describes the mass flow over time [m³/h] of the gaseous medium streaming through the valve 100. At the left end of the diagram, the opening characteristic of the valve 100 in the closed position I is shown, so that 0 m³/h of the gaseous medium flows through the valve 100. At the right end of the diagram, the opening characteristic of the valve 100 is shown, if the valve cap 120 is in the open position II, so that a maximum of e.g. 500 m³/h of the gaseous medium flows through the valve 100. The ordinate of the diagram describes the pressure difference between the interior of the valve 100 and the environment in mbar (millibar) or vice versa.

As can be taken from the diagram, between a pressure difference of 10 mbar to 10,11 mbar, the valve cap 120 leaves the closed position I and a gentle flow rate of 0 m³/h to 80 m³/h is generated (steep incline of the curve). If the pressure difference further increases between 10,11 mbar to 50 mbar, the flow rate of the gaseous medium increases more rapidly than between the pressure difference of 10 mbar to 10,11 mbar.

Between the pressure difference of 10 mbar to 10,11 mbar, the conical portions 114, 124 defines the smoothly increasing flow rate of the gaseous medium . If the valve cap 120 further pivots to the open position II, the conical portions 114, 124 are further spaced between each other due to the pivoting of the valve cap 120, so that a faster increase of the flow rate is caused (gentle incline of the curve).

Due to the gentle increase of the flow rate under small pressure differences, an abrupt closing of the valve cap 120 is prevented.

Furthermore, the valve cap 120 is more inertial, so that vibrations due to changing pressure differences may be decreased and reduced. Hence, rattling noise of the valve cap 120, if abutting against the valve seat 110 due to vibrations, is reduced.

Fig. 6 shows an exemplary embodiment of the valve 100 which comprises a weight holding element, in particular an L-shaped supporting rod 601, to which a plurality of weight elements 123 are attached. In Fig. 6 is shown the closed position I of the valve cap 120 with bolt lines and the open position II of the valve cap 120 with dotted lines. In the closed position I, the valve cap 120 comprises a valve cap surface which runs along a plane that has a normal nc, wherein in a closed position I the normal nc runs substantially along a first direction, which is in the shown exemplary embodiment parallel to a vertical direction 704 (shown in Fig, 7). In other embodiments, the first direction may have other orientations to the vertical direction 704. The L-shaped supporting rod 601 comprises a first section, which runs along e.g. the vertical direction 704 and a second section, which runs e.g. along a horizontal direction 705 (shown in Fig. 7). To the second section of the supporting rod 601 the weight elements 123 are attached at a desired position.

The second section of the supporting rod 601 runs between the pivot axis

121 and a central location of the valve cap 120. By adjusting the amount of weight elements 123 and by adjusting the locations of the weight elements 123 along the second section of the supporting rod 601, the total weight force w and the location of the centre of gravity 122 may be adjusted and hence the lever arms xl, x2 between the centre of gravity

122 and the pivot axis 121 in the closed position I and the open position II (or between both) of the valve cap 120 are adjustable. Hence, by adjusting the total weight of the weight elements 123 and by adjusting the location of the weight elements 123 along the second section of the supporting rod 601, the location of the centre of gravity 122 and hence the opening characteristics of the valve 100 is adjustable.

Fig. 7 shows a further exemplary embodiment wherein two valves 100, 300 are mounted with different orientation to the pipe 201. The pipe 201 in Fig. 7 comprises a first section, which runs substantially along a first direction, i.e. a vertical direction 704, a second section 702, which runs substantially along a second direction, i .e. a horizontal direction 705 and a third section 703 which connects the first section 701 and the second section 702. The second section 702 is for example coupled to a biogas storage 200. The first section 701 comprises an open end or a hole, wherein the open end or the hole is closed by a top end surface (wall) 706. To the top end surface 706, the valve 100 and in particular the valve seat 110 (not shown in Fig. 7) of the valve 100 is attached such that in an open position II of the valve 100 a fluid is guidable between the inner volume Vi and a surrounding volume Vs which surrounds the first section 701 of the pipe 201. The valve 100 comprises the supporting rod 601 (L- shaped) and the weight element 123, for example. The valve cap 120 is in the closed position I substantially parallel to the top end surface 706, i .e. the normal nc of the valve cap surface is e.g. parallel to the first normal nl of the top end surface 706.

Furthermore, in Fig. 7, a further valve 300 is shown. The further valve 300 and in particular the further valve seat 310 (not shown in Fig. 7) is mounted to a side surface 707 which second normal n2 is nonparallel to the vertical direction 704. The side surface 707 comprises a hole into which the further valve seat 310 is attached. The further valve 300 is aligned with respect to the side surface 707 in such a way, that the normal nc of the surface of the further valve cap 320 is substantially parallel with the second normal n2 in the closed position I.

In Fig. 7, the valve 100 is a pressure control valve, such that if the second pressure p2 exceeds a predetermined pressure value and is higher (by a predetermined amount) than the first and third gas pressure pl,p3, the valve cap 120 opens. Furthermore, in Fig. 7, the further valve 300 is a low pressure valve (vacuum valve), such that if the second gas pressure p2 falls below a predetermined pressure value and is lower (with a predetermined amount) than the first and third gas pressure pl,p3 of the gaseous medium, the further valve cap 320 opens and the gaseous medium streams from the further pipe 708 into the pipe 201. Furthermore, one of the valves 100, 300 may comprise a spring element 301 as shown in more detail in Fig. 3.

The valve 100 comprises an L-shaped supporting rod for the weight elements 123 and the further valve 300 comprises an I-shaped supporting rod 601 for the weight elements 123. By each supporting rod 601, the location of the centre of gravity 122 (shown in Fig. 6) of the respective valve cap 120, 320 and hence the distance along the horizontal direction 105 of the centre of gravity 122 to the respective pivot axis 121 is adjustable. Hence, the respective lever arms xl, x2 (shown in Fig. 6) are adjustable, so that an individual opening

characteristic for each valve 100, 300 is adjustable.

The second normal n2 of the side surface 707 is aligned in such a way, that the angle a exists between the second normal n2 of the side surface 707 and the horizontal direction 705, wherein the angle a is

approximately ± 1° to approximately ±30°, in particular approximately ± 10° degree. Moreover, in an exemplary embodiment, the top end surface 706 may be aligned with respect to the vertical direction 704 in such a way, that a further angle between the first normal nl and the vertical direction 704 exists, wherein the further angle may be

approximately ± 1° to ±45°. By an adjustment of the angle a between the normal nc of the further valve cap surface and the second normal n2 of the side surface 707 and additionally by the adjustment of the centre of gravity 122 of the further valve cap 320, the desired opening characteristics of the further valve 300 is adjustable. Both valves 100, 300 may be connected by the further pipe 708, which is located in the surrounding volume Vs. Furthermore, the further pipe 708 comprises a fluid exit 709 to the environment, such that the fluid inside the surrounding volume Vs may exit or enter the surrounding volume Vs through the fluid exit 709.

Moreover, the pipe 201 and the further pipe 708 may be surrounded by a housing 710 which is indicated by the dotted lines surrounding the embodiment shown in fig. 7. Hence, if the fluid is e.g. a warm biogas which exits the first section 701 of the pipe 201 through the valve 100 the functional components, such as the valves 100, 300, may be heated. In the exemplary embodiment shown in Fig. 7, the fluid inside of the pipe 201 exits through the valve 100 and flows inside the further pipe 708, which connects the valve 100 and the further valve 300. The fluid

(gaseous medium) in the further pipe 708 flows from the valve 100 to the further valve 300 or to the fluid exit 709. Hence, in the further pipe 708, a fluid, i .e. biogas, which exits the pipe 201, is gathered. Hence, if an underpressure of the second pressure p2 with respect to the first, third pressure pi, p3 occurs, the further valve 300 opens and the fluid, which has exit the valve 100 before, streams inside the pipe 201 again through the further valve 300. Hence, because the fluid inside the further pipe 708 comprises similar temperatures and similar fluid quality (e.g. similar biogas composition) the fluid inside the pipe 201 is not purified and down cooled by the entering fluid from the further pipe 708. Hence, a more effective control valve system for a gas storage 200, i .e. a biogas storage, is achieved. Moreover, under cold operation conditions of the valve system and the gas storage 200, a freezing of the valves 100, 300 may be prevented by the warm fluid in the further pipe 708. The fluid exit 709 defines the volume and the mass flow of a fluid exchange between the environment and the surrounding volume Vs. Thereby the predetermined dimensions of the fluid exit 709 control a loss of heat and a loss of second, third gas pressure p2, p3.

It should be noted that the term "comprising" does not exclude other elements or steps and "a" or "an" does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

List of reference signs:

100 valve

110 valve seat

111 duct

112 edge

113 pivot joint

114 first conical portion

115 centre axis of duct

120 valve cap

121 pivot axis

122 centre of gravity

123 weight element

124 second conical portion

200 gas storage

201 pipe

202 protective cover

203 sealing element

300 further valve

301 spring element

310 further valve seat

311 further duct

312 further edge

313 further pivot joint

320 further valve cap

321 further pivot axis

322 further centre of gravity

323 further weight element

324 further second conical portion

601 supporting rod

701 first section 702 second section

703 third section

704 vertical direction

705 horizontal direction

706 top surface

707 side surface

708 further pipe

709 fluid exit

710 housing

I closed position of the valve cap

II open position of the valve cap

W weight force

P component of pressure force in gravity direction

F spring force

pi first pressure

p2 second pressure

p3 third pressure

xl lever arm of the weight force to the pivot axis in the closed

position of the valve cap

x2 lever arm of the weight force to the pivot axis in an open position of the valve cap

nl first normal of top surface

n2 second normal of side surface

nc normal of valve cap surface

Vi inner volume

Vs surrounding volume

M turning moment

Claims

C L A I M S

1. Valve (100) for a gas storage (200), the valve (100) comprising a valve seat (110), and

a valve cap (120),

wherein the valve seat (110) comprises a duct (111) which has a centre axis (115) and through which a gaseous medium is flowable and an edge (112) which surrounds the duct (111),

wherein the valve cap (120) is mounted pivotable at the edge (112) in such a way that it is pivotably around the pivot axis (121), and wherein the pivot axis (121) is spaced apart from the centre axis

(115).

2. Valve (100) according to claim 1,

wherein the valve cap (120) comprises a weight holding element for holding a weight element (123) for adjusting the weight force (W) to the valve cap (120).

3. Valve (100) according to claim 2,

wherein the weight holding element is formed for detachably mounting the weight element (123) to the valve cap (120).

4. Valve (100) according to claim 2 or 3,

wherein the valve cap (120) comprises a surface with a normal (nc),

wherein the weight holding element runs at least partially parallel with respect to the normal (nc) and/or at least partially nonparallel with respect to the normal (nc),

wherein the weight holding element is formed in such a way that the weight element (123) is mountable to a predefined location along the weight holding element, so that the distance of the centre of gravity

(122) with respect to the pivot axis (121) is adjustable.

5. Valve (100) according to one of the claims 2 to 4,

wherein the weight holding element comprises a supporting rod

(601), in particular an L-shaped supporting rod or an I-shaped supporting rod, and

wherein the weight element (123) or a plurality of weight elements

(123) are detachably mountable to the supporting rod (601).

6. Valve (100) according to one of the claims 1 to 5,

wherein the duct (111) comprises a first conical portion (114) with a first cone angle, and

wherein the valve cap (120) comprises a second conical portion (124) with a second cone angle which corresponds to the first cone angle in such a way that a form closure between the valve seat (110) and the valve cap (120) is achievable.

7. Valve (100) according to one of the claims 1 to 6,

wherein the valve cap (120) is arranged at the valve seat (110) in such a way that the valve cap (120) is pivotable outside of the duct (111).

8. Valve (100) according to one of the claims 1 to 7, further comprising

a spring element,

wherein the valve cap (120) is arranged at the valve seat (110) in such a way that the valve cap (120) is pivotable inside of the duct (111), wherein the spring element is mounted to the cap element (120) in such a way that a component of a spring force (F) of the spring element counteracts to the weight force (W) of the valve cap (120).

9. Valve (100) according to of one of the claims 1 to 8, further comprising

a sealing element mounted for sealing the valve cap (120) with the valve seat (110) in the closed position (I).

10. Valve (100) according to one of the claims 1 to 9, further comprising

a protective cover which is mounted to the valve seat (110) for preventing pollutant to enter the duct (111).

11. Valve (100) according to of one of the claims 1 to 10,

wherein the valve cap (120) and/or the valve seat (110)

comprise(s) a coating for preventing condensation.

12. Gas storage (200) for storing a gaseous medium, the gas storage (200) comprising

a valve (100) as set forth in one of the claims 1 to 11.

13. Gas storage (200) according to claim 12, further comprising

a pipe (201) for supplying the gaseous medium between the gas storage (200) and the environment,

wherein the valve (100) is connected to the pipe (201) such that the flow rate of the gaseous medium through the pipe (201) is

controllable by the valve (100).

14. Gas storage (200) according to claim 13, further comprising

a further valve (300) as set forth in one of the claims 1 to 11, wherein the further valve (300) is connected to the pipe (201) such that the flow rate of the gaseous medium through the pipe (201) is controllable by the further valve (300).

15. Gas storage (200) according to claim 14,

wherein the pipe (201) comprises a first section (701) which extends along a first direction,

wherein the first section (701) comprises a top end surface (702) which first normal (nl) is parallel to the first direction,

wherein the top end surface (706) separates an inner volume (Vi) of the pipe (201) from a surrounding volume (Vs) that surrounds the pipe

(201),

wherein the valve (100) as set forth in one of the claims 1 to 11 is connected to the top end surface (706) for providing a fluid connection between the inner volume (Vi) and the surrounding volume (Vs), and wherein the valve cap (120) is aligned to the top end surface (706) such that a normal (nc) of a surface of the valve cap (120) is parallel with the first normal (nl) of the top end surface (706) in the closed position (I).

16. Gas storage (200) according to claim 14 or 15,

wherein the first section (701) comprises a side surface (707) which second normal (n2) is nonparallel to the first direction,

wherein the side surface (707) separates the inner volume (Vi) of the pipe (201) from the surrounding volume (Vs) that surrounds the pipe (201),

wherein the further valve (300) as set forth in one of the claims 1 to 11 is connected to the side surface for providing a fluid connection between the inner volume (Vi) and the surrounding volume (Vs), and wherein the further valve cap (320) is aligned to the side surface (707) such that a normal (nc) of a surface of the further valve cap (320) is parallel with the second normal (n2) in the closed position (I).

17. Gas storage (200) according to claim 16, wherein an angle (a) between the second normal (n2) of the side surface (707) and a horizontal direction (705) is ±5° to ±30° degrees.

18. Gas storage (200) according to claim 17, further comprising

a further pipe (708) which is located in the surrounding volume

(Vs),

wherein the further pipe (708) connects the top end surface (706) and the side surface (707) in such a way that a fluid is guidable in the further pipe (708) between the top end surface (706) and the side surface (707).

19. Gas storage (200) according to claim 18,

wherein the valve (100) is a valve according to claim 7, and wherein the further valve (300) is a valve according to claim 8.

20. Method of manufacturing a valve (100) for a gas storage (200) for storing a gaseous medium, the method comprising

forming a valve seat (110) comprising a duct (111) which has a centre axis (115) and through which a gaseous medium is flowable and an edge (112) which surrounds the duct (111),

forming a valve cap (120) which is mounted pivotable at the edge (112) in such a way that it is pivotably around the pivot axis (121), and spacing the pivot axis (121) apart from the centre axis (115).

21. Use of a gas storage (200) as set forth in one of the claims 12 to 19 as a biogas storage (200).