Fuel gas storage system

Abstract

The application relates to a fuel gas storage system (200, 300) comprising at least one fuel gas connection (222, 322) configured for supplying fuel gas from a fuel gas distribution network (202, 302), at least one fuel gas compression arrangement (204, 304) configured for compressing the supplied fuel gas, at least one fuel gas storage unit (206, 306) configured for storing the compressed fuel gas, at least one fuel gas expansion arrangement (208, 308) configured for expanding the fuel gas withdrawn from the fuel gas storage unit (206, 306), wherein the fuel gas connection (222, 322) is configured for feeding the expanded fuel gas into the fuel gas distribution network (202, 302), and wherein the fuel gas expansion arrangement (208, 308) comprises at least one expansion machine (230, 330, 430).

Description

[0001] The application relates to a fuel gas storage system, comprising at least one fuel gas connection configured to provide a fuel gas from a fuel gas distribution network, at least one fuel gas compression arrangement configured to compress the provided fuel gas, at least one fuel gas storage device (e.g., a cavity artificially created in salt rock) configured to store the compressed fuel gas, and at least one fuel gas expansion arrangement configured to expand the fuel gas extracted from the fuel gas storage device, wherein the fuel gas connection is configured to feed the expanded fuel gas into the (public) fuel gas distribution network. Furthermore, the application relates to a method for operating a fuel gas storage system.

[0002] To generate electrical energy and / or heat, it is known from the prior art to burn a fuel gas in a power plant. Examples of fuel gases include natural gas, biogas, and hydrogen. The fuel gas is transported via a pipeline network or fuel gas distribution network and regularly stored using fuel gas storage systems.

[0003] Known fuel gas storage systems comprise at least one fuel gas storage unit in which the fuel gas is temporarily stored. For this purpose, the fuel gas supplied via the fuel gas distribution network is first compressed by a compression arrangement. The compressed fuel gas is then stored in the fuel gas storage unit. When fuel gas is needed, the fuel gas is withdrawn from the storage unit via an expansion arrangement. The expanded fuel gas is then fed back into the fuel gas distribution network. Furthermore, at least one further process plant can be provided for the specification-compliant processing of the stored fuel gas before it is returned to the fuel gas distribution network, such as a fuel gas dryer or the like. Document US 9803803 B1 discloses a fuel gas storage system.

[0004] The Figure 1shows an exemplary prior art fuel gas storage system 100. The fuel gas storage system 100 includes a fuel gas compression assembly 104, a fuel gas storage 106, and a fuel gas expansion assembly 108. Furthermore, an internal fuel gas distribution network 126 in the form of a plurality of pipes is provided.

[0005] The fuel gas storage system 100 is coupled to a public fuel gas distribution network 102 via a fuel gas connection 122. The fuel gas connection 122 is configured to provide fuel gas from the fuel gas distribution network 102. This fuel gas is provided or supplied, in particular, to the fuel gas compression arrangement 104. It should be noted that the flow direction of the fuel gas in the internal fuel gas distribution network 126 is indicated by arrows.

[0006] A fuel gas compression arrangement 104 typically has a plurality of compression stages 114.1, 114.2, 114.x, where x is a natural number. A compression stage 114.1, 114.2, 114.x of the prior art, in particular, has a compressor 110 and an air cooler 112 downstream of the respective compressor 110.

[0007] The fuel gas provided through the fuel gas connection 122 normally has a temperature between approximately 8° C and 15° C before the first compression stage 114.1. The compressor 110 of the first compression stage 114.1 increases the temperature of the fuel gas to approximately 50° C to 150° C. In particular, the work performed on the fuel gas by the compressor 110 increases the internal energy of the fuel gas and thus its temperature.

[0008] To avoid damage to the technical components of the compression stages 114.1, 114.2, 114.x, particularly when multiple compression stages 114.1, 114.2, 114.x are used, it is known that an air cooler 112 is connected downstream of each compressor 110. For example, in the first compression stage 114.1, the fuel gas heated to a temperature of up to approximately 150°C can be cooled back down to approximately 45°C by a downstream air cooler 112.

[0009] After the fuel gas has been compressed by the last compression stage 114.x and subsequently cooled down, it is fed into the fuel gas storage 106 through a storage connection 124 of the fuel gas storage 106 and stored there, in particular temporarily stored.

[0010] In particular, when there is a demand for fuel gas in the external fuel gas distribution network 102, the stored fuel gas is withdrawn from the fuel gas storage 106 via the storage connection 124 and, in particular, provided to a fuel gas expansion arrangement 108. In the case of natural gas, the prior art initially involves heating the withdrawn natural gas via a heating device 116 of the fuel gas expansion arrangement 108. The preheated natural gas is then expanded via a control valve 118 or expansion valve 118. The expanded natural gas is fed to a gas treatment unit 120 and fed into the fuel gas distribution network 102 via the fuel gas connection.

[0011] If the fuel gas is hydrogen, then, due to the negative Joule-Thomson coefficient of hydrogen compared to natural gas, instead of heating the extracted hydrogen, it is pre-cooled by a cooling device 116 of the fuel gas expansion arrangement 108. The pre-cooled hydrogen is then expanded via the control valve 118 or expansion valve 118. The expanded hydrogen is fed to a gas treatment unit 120 and fed into the fuel gas distribution network 102 via the fuel gas connection.

[0012] Operating such a fuel gas storage system requires a significant amount of external energy. For example, the compressors and air coolers of the fuel gas compression system must be supplied with electrical energy from an external energy source. Likewise, the electrical components of the described expansion system must be supplied with electrical energy from an external energy source. In other words, the energy consumption for storing and / or retrieving fuel gas is high in the known fuel gas storage systems.

[0013] Therefore, the application is based on the object of providing a fuel gas storage system in which the need for energy from external energy sources is at least reduced.

[0014] This object is achieved according to a first aspect of the application by a fuel gas storage system according to claim 1. The fuel gas storage system comprises at least one fuel gas connection. The fuel gas connection is configured to provide a fuel gas from a fuel gas distribution network. The fuel gas storage system comprises at least one fuel gas compression arrangement. The fuel gas compression arrangement is configured to compress the provided fuel gas. The fuel gas storage system comprises at least one fuel gas storage device. The fuel gas storage device is configured to store the compressed fuel gas. The fuel gas storage system comprises at least one fuel gas expansion arrangement. The fuel gas expansion arrangement is configured to expand the fuel gas withdrawn from the fuel gas storage device. The fuel gas connection is configured to feed the expanded fuel gas into the fuel gas distribution network.The fuel gas expansion arrangement comprises at least one expansion working machine, in particular designed to expand the extracted fuel gas, particularly preferably to utilize the internal energy of the fuel gas.

[0015] By providing, in contrast to the prior art, a fuel gas storage system with a fuel gas expansion arrangement, wherein the fuel gas expansion arrangement comprises at least one expansion machine, in particular configured to expand the extracted fuel gas, the demand for energy from external energy sources is at least reduced. Thus, the expansion machine, preferably in the form of a turbine device, can replace a heating device or a cooling device as well as the control valve, so that the external energy demand is reduced. Furthermore, the use of a turbine device, in particular, offers the possibility of recovering energy through the expansion process or during the expansion process. In particular, the expansion machine can convert the internal energy of the fuel gas into usable energy.

[0016] The fuel gas storage system is used to store a fuel gas, in particular for temporary storage of the fuel gas.

[0017] A fuel gas is understood, in particular, to be a combustible useful gas that is burned or oxidized in an electrochemical converter (e.g., a combustion device, a fuel cell, etc.) of a fuel gas consumer to provide, for example, thermal energy and / or electrical energy. According to a preferred embodiment of the fuel gas storage system according to the application, the fuel gas can be selected from the group comprising: natural gas, biogas, and hydrogen. In other words, the fuel gas storage system is particularly configured for storing and retrieving natural gas or hydrogen.

[0018] A fuel gas is transported, in particular, via an (external and especially public) fuel gas distribution network from a fuel gas source to a fuel gas consumer (e.g., a gas-fired power plant, a building's gas heating system, etc.). A fuel gas distribution network or fuel gas transport network typically comprises a number of transport network pipes or transport network lines through which the fuel gas is transported.

[0019] A fuel gas storage system is connected to such an external fuel gas distribution network via at least one fuel gas connection. If, for example, more fuel gas is fed into the external fuel gas distribution network by the at least one fuel gas source than is (currently) required by the at least one fuel gas consumer, then fuel gas can be extracted from the external fuel gas distribution network and stored in a fuel gas storage unit of the fuel gas storage system.

[0020] If the fuel gas is natural gas, for example, the fuel gas storage system can be operated essentially seasonally. This means, in particular, that fuel gas is stored during the warm months and removed during the cold months.

[0021] In the case of the particularly preferred fuel gas hydrogen, multi-cyclic operation of the fuel gas storage system can be provided. The operation of the fuel gas storage system can in particular follow the availability of electrical energy from so-called renewable energy sources (e.g. sun, wind, etc.). In the case of hydrogen, the fuel source can in particular be an electrically operated electrolysis plant. The electrolysis plant can in particular be operated with electrical energy to produce hydrogen when electrical energy is available from the renewable energy sources, for example when more electrical energy is generated by wind farms and / or photovoltaic parks due to the corresponding meteorological conditions (e.g. high wind speeds and / or high solar radiation) than is required by electrical consumers of an external (public) electricity distribution grid.The hydrogen produced can be at least partially taken from the external fuel gas distribution network in the form of a hydrogen distribution network and (temporarily) stored in the fuel gas storage system.

[0022] If electrical energy from renewable energy sources is not or hardly available, for example if less electrical energy is generated by wind farms and / or photovoltaic parks due to the corresponding meteorological conditions (e.g. low wind speed and / or low solar radiation) than is required by electrical consumers in the electricity distribution network, stored hydrogen can be taken from the fuel gas storage system, fed into the hydrogen distribution network and made available to a hydrogen power plant in order to generate electrical energy, in particular by burning the hydrogen provided.

[0023] The fuel gas connection (e.g., comprising a controllable valve arrangement) is fluidly coupled or connected to a fuel gas compression arrangement. In particular, the fuel gas storage system can comprise an internal refrigerant distribution network (e.g., formed by a plurality of transport pipes). It is understood that additional modules, e.g., for fuel gas purification and / or treatment, can be arranged between the fuel gas connection and the fuel gas compression arrangement.

[0024] The fuel gas compression arrangement is configured to compress the provided fuel gas. The fuel gas compression arrangement may comprise at least one compressor. A compressor is configured to supply mechanical work to the (enclosed) fuel gas, thereby increasing, in particular, the pressure and density of the fuel gas.

[0025] Preferably, a fuel gas compression arrangement can comprise a plurality of compression stages, each with a compressor, in order to effect a specific (predeterminable) compression of the fuel gas provided.

[0026] The fuel gas compression assembly is fluidically coupled or connected to the fuel storage unit. In particular, the fuel gas storage unit may include a storage connection. The fuel gas compression assembly is connected, in particular, to the storage connection.

[0027] The storage connection (e.g. comprising a controllable valve arrangement) can be configured to feed the compressed fuel gas to be stored into the fuel gas storage and / or to remove the stored fuel gas from the fuel gas storage.

[0028] Furthermore, the fuel gas storage system comprises at least one fuel gas expansion assembly, which is fluidically connected, in particular, to the storage connection. According to the application, the fuel gas expansion assembly has at least one expansion machine configured to expand the fuel gas extracted from the fuel gas storage. Expansion refers, in particular, to reducing the pressure and density of the fuel gas.

[0029] The expansion working machine can preferably be a turbine device. In other variants of the application, the expansion working machine can also be a rotary piston device or the like.

[0030] A turbine device according to the application may comprise a turbine housing. The turbine housing may be made of metal, in particular steel. The turbine housing may have an inlet to which a pipe or line of the internal refrigerant distribution network can be connected. The pipe may lead to the storage connection.

[0031] The turbine housing may have an outlet, particularly on the side of the turbine housing opposite the inlet, to which another pipe or a second line of the internal refrigerant distribution network can be connected. The pipes may be flange-mounted, particularly at the inlet or outlet.

[0032] The turbine device comprises, in particular, at least one rotor arranged (or mounted) on a turbine shaft. The turbine shaft is arranged, in particular, within the turbine housing. The turbine shaft can thus be coupled (mechanically, in particular torque-locked) to the rotor. The rotor comprises, in particular, an impeller with a plurality of impeller blades.

[0033] The fuel gas flowing from the inlet to the outlet of the turbine device causes, in particular, a mechanical movement of the rotor assembly. This leads to a relaxation of the fuel gas or the fuel gas pressure. Furthermore, the mechanical movement of the rotor assembly is transferred to the turbine shaft, in particular into a rotational movement of the turbine shaft. This rotational movement can be further utilized, as will be described below.

[0034] The expanded fuel gas is fed (again) into the external fuel gas distribution network via the fuel gas connection, if necessary after further fuel gas processing.

[0035] According to a further embodiment of the fuel gas storage system according to the application, the at least one fuel gas storage device can be a cavern, in particular a salt cavern. The advantage of a salt cavern is, in particular, that additional lining is unnecessary due to the petrophysical properties of salt.

[0036] According to a further preferred embodiment of the fuel gas storage system according to the application, the expansion working machine can be a turbine device and comprise at least one generator. The generator can be configured to generate electrical energy.

[0037] Preferably, the turbine shaft is (mechanically) coupled to the at least one generator. The generator is thus arranged or mounted on the turbine shaft. In other variants, an indirect coupling may be provided, for example, a transmission may be interposed.

[0038] The generator can, in particular, convert the rotational movement of the shaft or the rotational energy into electrical energy. In other words, the at least one generator, preferably coupled to the turbine shaft, is particularly configured to convert the mechanical energy generated during the relaxation process into electrical energy.

[0039] The generator can be an asynchronous machine, for example. The at least one generator can be arranged, in particular, in a "floating" manner within the turbine housing. The fuel gas can flow at least partially around the generator or the generator housing.

[0040] The at least one generator can be arranged upstream of the rotor assembly in the flow direction. Alternatively, the at least one generator can be arranged downstream of the rotor assembly, or, in addition to the generator upstream of the rotor assembly in the flow direction, another generator can be arranged downstream of the rotor assembly. The arrangement of the at least one generator can depend, in particular, on the fuel gas to be expanded.

[0041] Especially with hydrogen, it is advantageous to position the generator upstream of the impeller in the direction of flow. This arrangement can achieve optimized cooling of the generator in hydrogen.

[0042] With natural gas or biogas, it can be advantageous to position the generator downstream of the impeller. This is because the gas expansion lowers the gas temperature, resulting in a lower temperature downstream of the impeller than upstream of the impeller. Cooling can be improved. The advantage of two generators is that they can have a smaller interference contour with the same total output.

[0043] According to a further embodiment of the fuel gas storage system according to the application, the fuel gas storage system can comprise an internal power grid. The internal power grid can be formed from at least one electrically conductive line, in particular a plurality of lines. It is understood that additional components, such as fuses, switches, etc., can be provided.

[0044] The internal power grid can, in particular, be configured to supply at least one electrical consumer of the fuel gas storage system at least partially with the electrical energy generated by the generator. This allows the electrical energy from an external power source (in particular an external power distribution grid) required to operate the fuel gas storage system to be further reduced. In particular, the at least one electrical consumer can be the at least one compressor of the fuel gas compression arrangement. Preferably, each electrical consumer of the fuel gas storage system can be connected to the internal power grid.

[0045] In variants of the application, it can be provided that the electrical energy generated by the at least one generator of the turbine device can be fed into the (external) electricity distribution network (via an electrical grid connection) if more electrical energy is generated by the generator than is required in the fuel gas storage system and / or if there is a high energy demand in the (external) electricity distribution network (or during peak load times).

[0046] In particular, it has been recognized that hydrogen is often extracted during peak load times, i.e., when (currently) less electrical energy is fed into the external power distribution grid than is extracted from it. On the one hand, the extracted hydrogen can be burned to generate electrical energy in a hydrogen power plant. Additionally, the electrical energy generated by the at least one generator of the turbine device can be fed into the power distribution grid, particularly to further stabilize the power distribution grid.

[0047] Furthermore, according to a further embodiment of the fuel gas storage system according to the application, the fuel gas storage system can comprise at least one rechargeable battery connected to the internal power grid. In particular, if the electrical energy demand of the fuel gas storage system during expansion of the fuel gas or during removal from storage is lower than the electrical energy generated by the at least one generator, excess electrical energy can be (at least partially) (temporarily) stored in the battery. During storage or compression of the fuel gas, the at least one electrical consumer of the fuel gas compression arrangement can then preferably be supplied (at least partially) with the electrical energy stored in the battery.

[0048] According to a particularly preferred embodiment of the fuel gas storage system according to the application, the expansion machine, in particular the turbine device, can comprise at least one first heat exchanger. The at least one first heat exchanger can be configured to cool a fluid refrigerant. In variants of the application, for example, two first heat exchangers can also be provided in the expansion machine. A first heat exchanger is configured, in particular, to (partially) transfer the thermal energy of the fuel gas to the fluid refrigerant.

[0049] Preferably, the fluid refrigerant can be selected from the group comprising R124a, CO 2 , and NH 3 . It is understood that in other variants of the application, a different refrigerant can also be used. In particular, partially halogenated hydrocarbons can be used as refrigerants.

[0050] Preferably, the at least one first heat exchanger can be integrated in the turbine housing, in particular arranged behind the impeller as seen in the flow direction.

[0051] In a preferred embodiment, the generator can be arranged or mounted on the turbine shaft in the direction of flow upstream of the rotor assembly, and the first heat exchanger can be arranged or mounted on the turbine shaft in the direction of flow downstream of the rotor assembly. In variants of the application, the at least one first heat exchanger can also be arranged in the region of the outlet of the turbine housing or downstream of the outlet of the turbine housing.

[0052] In particular, it has been recognized that the fuel gas is cooled by the expansion by means of the turbine device. The cooled fuel gas can be used, in particular, to cool and condense the fluid refrigerant.

[0053] According to a further preferred embodiment of the fuel gas storage system according to the application, the fuel gas compression arrangement can comprise at least one second heat exchanger. The second heat exchanger can be configured to cool the fuel gas. In particular, the second heat exchanger is configured to cool the fuel gas flowing into and / or through the fuel gas compression arrangement.

[0054] The fuel gas storage system can preferably comprise at least one internal refrigerant distribution network. The refrigerant distribution network can comprise at least one pipe or line, in particular a plurality of pipes or lines. The internal refrigerant distribution network can be configured to supply the at least one second heat exchanger at least partially with the fluid refrigerant cooled by the first heat exchanger. In particular, at least the second heat exchanger can be connected to the first heat exchanger (directly or indirectly) via the internal refrigerant distribution network.

[0055] In particular, the refrigerant cooled by the first heat exchanger can be transported through the internal refrigerant distribution network, e.g., via a forward channel, to the second heat exchanger, such that provided fuel gas and / or compressed fuel gas is cooled. The refrigerant heated by the second heat exchanger can be transported through the internal refrigerant distribution network, e.g., via a return channel, to the first heat exchanger, such that the heated refrigerant is (re)cooled by the cooled fuel gas. In other words, the fuel gas storage system can preferably comprise a refrigeration circuit, which can be formed by at least a first heat exchanger, a second heat exchanger, and the internal refrigerant distribution network.

[0056] The energy requirement from external energy sources can be further reduced. Air coolers can be omitted from the fuel gas compression system, or at least the number of air coolers and / or the air cooler power can be reduced.

[0057] According to a further preferred embodiment of the fuel gas storage system according to the application, the at least one second heat exchanger can be arranged in the fuel gas compression arrangement such that the provided fuel gas is cooled (as viewed in the flow direction) upstream of the at least one compressor (or the first compression stage) of the fuel gas compression arrangement. In other words, as viewed in the flow direction, the at least one second heat exchanger can be positioned between the fuel gas connection and the first compression stage of the fuel gas compression arrangement.

[0058] In particular, it has been recognized according to the application that, in contrast to the prior art, in which no air cooler is provided before the first compression stage due to the low performance of an air cooler, a second heat exchanger can advantageously be installed before the first compression stage in order to cool the provided fuel gas before the first compression.

[0059] In particular, tests have shown that the provided fuel gas can be cooled by the second heat exchanger to a temperature of at least less than 0°C, in particular less than -10°C, preferably less than -15°C, particularly preferably to at least (less than) -20°C. This makes it possible for the fuel gas (in particular independent of the outside temperature) to be fed into the first compressor at a temperature between in particular -10°C and -20°C instead of a temperature between 8°C and 15°C. This temperature difference can extend through all compression stages. This makes it possible, in particular, to design the at least one compressor or the at least one compression system, in particular all compressors, with lower power compared to a fuel gas compression arrangement of the prior art.

[0060] According to a further embodiment of the fuel gas storage system according to the application, at least one further second heat exchanger can be arranged downstream of the at least one first compressor and in particular upstream of another compressor of the fuel gas compression arrangement. For example, at least one further second heat exchanger can be arranged downstream of each compressor. In particular, every second heat exchanger can be connected to the internal refrigerant distribution network. In variants of the application, only one or two second heat exchangers and, in particular, at least one additional air cooler can be provided.

[0061] Furthermore, according to a further preferred embodiment of the fuel gas storage system according to the application, the fuel gas storage system can comprise at least one first refrigerant storage unit. The at least one first refrigerant storage unit can be configured to store (in particular temporarily store) the fluid refrigerant cooled by the first heat exchanger. The at least one first refrigerant storage unit can be connected to the internal refrigerant distribution network, in particular to the forward channel.

[0062] By providing at least one first refrigerant reservoir, it is possible to temporarily store the cooled refrigerant in the first refrigerant reservoir if cooling of the fuel gas by the at least one second heat exchanger is not required during expansion. If cooling of the fuel gas by the at least one second heat exchanger is then required (and in particular, expansion is not performed), the second heat exchanger can be supplied with cooled refrigerant from the first refrigerant reservoir.

[0063] According to a further embodiment of the fuel gas storage system according to the application, the fuel gas storage system can comprise at least one second refrigerant storage unit. The second refrigerant storage unit can be configured to store the fluid refrigerant heated by the at least one second heat exchanger. The at least one second refrigerant storage unit can be connected to the internal refrigerant distribution network, in particular to the return channel.

[0064] By providing at least one second refrigerant reservoir, it is possible to ensure that, in the event that cooling of the fluid refrigerant by the at least one first heat exchanger is not possible during compression (e.g., because no expansion occurs immediately), the heated refrigerant can be temporarily stored in the second refrigerant reservoir. This can, for example, prevent the heated refrigerant from heating the cooled refrigerant stored in the first refrigerant reservoir.

[0065] If cooling is then possible through the at least one first heat exchanger (and in particular expansion of the fuel gas is carried out), the first heat exchanger can be supplied with the heated refrigerant from the second refrigerant storage device.

[0066] In particular, the refrigeration circuit may comprise the first refrigerant storage and / or the second refrigerant storage.

[0067] Preferably, the fuel gas storage system can comprise at least one refrigerant compressor. The refrigerant compressor can be configured to compress the fluid refrigerant heated by the at least one second heat exchanger. In particular, the refrigerant compressor can be installed in the return channel, in particular downstream of the optional second refrigerant storage unit, as seen in the flow direction.

[0068] In particular, for optimized flow of the fuel gas onto the rotor assembly (in particular the impeller blades), a guide device or steering device can be arranged upstream of the rotor assembly of the turbine device in the flow direction. The guide device is particularly adapted to the rotor assembly. The guide device is preferably configured to direct the fuel gas onto the rotor assembly in a specific direction.

[0069] Furthermore, the fuel gas storage system can preferably comprise a control device configured to control the fuel gas storage system. In particular, the control device can be configured to control the storage process, i.e., in particular by appropriately controlling the fuel gas connection (e.g., the valve arrangement), the fuel gas compression arrangement (e.g., the at least one compressor), and / or the storage connection (e.g., the valve arrangement). Furthermore, the control device can be configured to control the removal process, i.e., in particular by appropriately controlling the fuel gas connection (e.g., the valve arrangement), the fuel gas expansion arrangement, and / or the storage connection (e.g., the valve arrangement).

[0070] Particularly preferably, the control device can control the previously described refrigeration circuit (as described above), in particular by controlling the first and / or second heat exchanger (e.g., the corresponding valves), the first and / or second refrigerant reservoir (e.g., the corresponding valves), and / or the refrigerant compressor. Controlling the refrigeration circuit can depend on temperature data, e.g., of the first and / or second refrigerant reservoir, which can be provided, for example, by temperature sensors of the control device.

[0071] Furthermore, the control device can be configured to control the distribution of the electrical energy generated by the generator. The control can depend on the grid status (in particular the grid frequency) of the external power distribution grid to which the fuel gas storage system is connected and / or on the internal power demand of the fuel gas storage system, as previously described.

[0072] In particular, the control device can comprise a communication module configured to receive an instruction message for storing and / or retrieving fuel gas. The control device can then control the fuel gas storage system accordingly.

[0073] A further aspect of the application is a method for operating a fuel gas storage system, in particular a previously described fuel gas storage system. The method comprises: Providing, through at least one fuel gas connection, a fuel gas from a fuel gas distribution network, compressing, through at least one fuel gas compression arrangement, the provided fuel gas, storing, through at least one fuel gas storage, the compressed fuel gas, expanding, through at least one turbine device of at least one fuel gas expansion arrangement, the fuel gas taken from the fuel gas storage, and feeding, through the fuel gas connection, the expanded fuel gas into the fuel gas distribution network.

[0074] It should be noted that a module, a device (e.g., the control device), etc., in the present case, can be formed at least partially by software elements (particularly in the form of computer code executable by a processor) and / or at least partially by hardware elements (processor, memory means, actuator, etc.). Furthermore, it should be noted that expressions such as "first," "second," etc., do not indicate an order, but merely serve to distinguish between two elements.

[0075] The features of the fuel gas storage systems and methods can be freely combined with one another. In particular, features of the description and / or the dependent claims, even if they completely or partially circumvent features of the independent claims, can be independently inventive, either alone or in freely combined form.

[0076] There are now numerous possibilities for designing and further developing the fuel gas storage system and the method according to the application. Reference is made, on the one hand, to the patent claims subordinate to the independent patent claims and, on the other hand, to the description of exemplary embodiments in conjunction with the drawing. The drawing shows: Fig. 1 is a schematic view of an exemplary prior art fuel gas storage system, Fig. 2 is a schematic view of an embodiment of a fuel gas storage system according to the present application, Fig. 3 is a schematic view of another embodiment of a fuel gas storage system according to the present application, Fig. 4 is a schematic view of an embodiment of a turbine device according to the present application for a fuel gas storage system according to the present application, and Fig. 5 is a diagram of an embodiment of a method according to the present application.

[0077] Similar reference numerals are used below for similar elements.

[0078] The Figure 2shows a schematic view of an embodiment of a fuel gas storage system 200 according to the present application. The fuel gas storage system 200 serves for the temporary storage of a fuel gas, preferably natural gas or hydrogen.

[0079] The fuel gas storage system 200 comprises at least one fuel gas connection 222 (e.g., with a controllable valve arrangement (not shown)) configured to provide a fuel gas from an (external) fuel gas distribution network 202. In other words, fuel gas can be withdrawn from the (external) fuel gas distribution network 202 through the fuel gas connection 222 and fed into the internal fuel gas distribution network 226 of the fuel gas storage system 200. The flow direction of the fuel gas is indicated in the figures, in particular by the arrows.

[0080] Furthermore, the fuel gas storage system 200 comprises at least one fuel gas compression arrangement 204, in particular with at least one compressor 210 or a compression system, configured to compress the provided fuel gas.

[0081] The fuel gas storage system 200 comprises at least one fuel gas storage unit 206. The fuel gas storage unit 206 can preferably be a salt cavern 206. The compressed fuel gas can be fed into the fuel gas storage unit 206 via a storage connection 224 (e.g., with a controllable valve arrangement) of the fuel gas storage unit 206. In other words, the fuel gas storage unit 206 is configured to store the compressed fuel gas.

[0082] As further shown in the Figure 2As can be seen, the fuel gas storage system 200 comprises at least one fuel gas expansion arrangement 208, configured to expand the fuel gas withdrawn from the fuel gas storage 206. In particular, the fuel gas can be withdrawn from the fuel gas storage 206 via the storage connection 224.

[0083] In contrast to the state of the art (cf. Figure 1 ), the fuel gas storage system 200 according to the application comprises at least one expansion machine 230. In the preferred embodiment shown, the expansion machine 230 is a turbine device 230 configured to expand the fuel gas extracted from the fuel gas storage 206 and, in particular, still compressed. In other variants of the application, the expansion machine can be a rotary piston device, a reciprocating piston device, or the like.

[0084] The fuel gas flowing from the inlet to the outlet of the turbine device 230 causes, in particular, a mechanical movement of a running device of the turbine device 230. This leads to a relaxation of the fuel gas or the fuel gas pressure.

[0085] The fuel gas connection 222 is further configured to feed the expanded fuel gas into the fuel gas distribution network 202.

[0086] The Figure 3 shows a schematic view of another preferred embodiment of a fuel gas storage system 300 according to the present application. To avoid repetition, only the differences from the previous embodiment according to Figure 2 described and otherwise referred to the explanations for this embodiment.

[0087] In the preferred embodiment shown, the turbine device 330 comprises a generator 334 and a first heat exchanger 336. It is understood that in variants of the application, only a generator (with a corresponding internal power network) and no heat exchanger or only a first heat exchanger (with a corresponding refrigerant distribution network) and no generator may be provided.

[0088] The generator 334 is configured to generate electrical energy. The generated electrical energy can be fed into an internal power grid 340 (formed by a plurality of electrically conductive lines) and / or into an external (public) power distribution grid 350. The distribution of the electrical energy to the internal power grid 340 and / or the external power distribution grid 350 can be carried out, in particular, by a control device 348 of the fuel gas storage system 300. This can depend, in particular, on the internal power demand and / or the grid status of the external power distribution grid 350.

[0089] In particular, at least one electrical consumer 310, 348 (compressor 310 and control device 348 are shown as examples of electrical consumers) of the fuel gas storage system 300 can be supplied with the electrical energy generated by the generator 334. Optionally, the fuel gas storage system 300 can include at least one rechargeable battery (not shown).

[0090] Furthermore, the Figure 3 As can be seen, the fuel gas storage system 300 in the present case comprises a refrigeration circuit 352. The refrigeration circuit 352 comprises at least one first heat exchanger 336. The first heat exchanger 336 is particularly designed for cooling or cooling a fluid refrigerant (in particular partially fluorinated hydrocarbons) of the refrigeration circuit 352.

[0091] The cooled refrigerant can be conducted via the internal refrigerant distribution network 342 of the refrigeration circuit 352 to at least one second heat exchanger 338.1, 338.2. In particular, the fuel gas compression arrangement 304 comprises the at least one second heat exchanger 338.1, 338.2. A second heat exchanger 338.1, 338.2 is particularly configured to cool the fuel gas flowing through the fuel gas compression arrangement 304.

[0092] As in the Figure 3 As shown, the at least one second heat exchanger 338.1 can be arranged, in particular in the flow direction, upstream of the first compressor 310 or the first compression stage 310. This second heat exchanger 338.1 is particularly configured to cool the fuel gas provided through the fuel gas connection 322 to at least less than -10°C, preferably to less than -15°C, particularly preferably to at least -20°C.

[0093] For example, the refrigeration circuit 352 can comprise at least one further second heat exchanger 338.2, for example, arranged between two compressors 310. In further variants of the application, at least one further second heat exchanger can be provided and / or at least one air cooler (which can in particular be connected to the internal power grid). It is understood that the fuel gas compression arrangement 304 can comprise three or more compressors or compression stages in other variants of the application.

[0094] Optionally, the refrigeration circuit 352 can include at least one first refrigerant reservoir 344. In particular, when cooling of the fuel gas by the second heat exchanger 338.1, 338.2 is not currently required (for example, because no fuel gas is currently being compressed), the cooled refrigerant can be temporarily stored in the first refrigerant reservoir 344. If cooling of the fuel gas by a second heat exchanger 338.1, 338.2 is then required (for example, because a fuel gas is currently being compressed), the refrigerant can be provided, in particular, by the first refrigerant reservoir 344 to the second heat exchanger 338.1, 338.2 (in particular, when no expansion of the fuel gas is currently taking place).

[0095] Furthermore, the refrigeration circuit 352 can include at least one second refrigerant reservoir 346. In particular, if the fluid refrigerant cannot be cooled by a first heat exchanger 336 at the moment (for example, because no fuel gas is being expanded at the moment), the heated refrigerant can be temporarily stored in the second refrigerant reservoir 346. If the fluid refrigerant can then be cooled by a first heat exchanger 336 (for example, because a fuel gas is being expanded at the moment), the refrigerant can be provided, in particular, by the second refrigerant reservoir 346 to the first heat exchanger 336 (in particular, if the fuel gas is not being expanded at the moment).

[0096] In variants of the application, the refrigeration circuit 352 may comprise further components, such as at least one refrigerant compressor (not shown), for example between the second refrigerant storage and the first heat exchanger.

[0097] The control of the refrigeration circuit 352, in particular the components 336, 344, 338.1, 338.2, 346 (or the various valves not shown) of the refrigeration circuit 352, can be carried out by the control device 348. Sensors not shown (e.g., temperature sensors for detecting the temperature in the refrigerant reservoirs 344, 346, fill level sensors for detecting the fill level in the refrigerant reservoirs 344, 346, etc.) can be arranged in the refrigeration circuit, which can provide the respectively detected sensor data to the control device 348. The control of the refrigeration circuit 352 can depend on this sensor data.

[0098] In addition, the control device 348 can be configured to control the storage process and / or the removal process, for example depending on a received control signal or instruction message, for example containing an instruction to store a specific amount of fuel gas, for example within a specific period of time, or to remove a specific amount of fuel gas, for example within a specific period of time.

[0099] It is understood that in variants of the application, a plurality of sequentially connected expansion working machines, in particular turbine devices, can also be implemented in the fuel gas expansion arrangement, in particular in order to maintain a certain pressure level.

[0100] The Figure 4shows a schematic view of a preferred embodiment of a turbine device 430 according to the present application for a fuel gas storage system according to the present application, for example as shown in the Figure 2 or Figure 3 is shown.

[0101] The turbine device 430 is used in particular to carry out a fuel gas pressure relief from a first fuel gas pressure level (upstream of the turbine device 430) to a second, lower fuel gas pressure level (downstream of the turbine device 430), wherein mechanical energy is preferably simultaneously converted into electrical energy by a generator 434 of the turbine device 430 and, in particular, a fluid coolant is cooled by a first heat exchanger 436.

[0102] The turbine device 430 shown comprises a turbine housing 456 (e.g., made of steel or another metal). The turbine housing 456 is, in particular, substantially tubular. In variants of the application, a different shape may also be provided.

[0103] The turbine housing 456 has an inlet 468 and an outlet 470. In the present embodiment, the arrow 472 indicates the flow direction of the fuel gas through the turbine device 430. As can be seen, the fuel gas flows through the turbine housing 456 from the inlet 468 to the outlet 470 essentially without a change in direction.

[0104] The illustrated turbine device 430 comprises at least one impeller 464 arranged on a turbine shaft 466. The impeller 464 may in particular comprise an impeller having a plurality of impeller blades.

[0105] Furthermore, in the present exemplary embodiment, the turbine device 430 comprises at least one guide device 462 arranged upstream of the impeller device 464 in the flow direction 472. The guide device 462 can in particular have a plurality of nozzle channels which can in particular impart a swirl to the fuel gas corresponding to the blading of the impeller 464 and preferably accelerate it.

[0106] The turbine device 430 shown comprises at least one generator 434 coupled to the turbine shaft 466, configured to convert mechanical energy into electrical energy. In particular, the kinetic energy of the fuel gas flowing through the turbine device 430 is converted into electrical energy by the rotor device 464, the turbine shaft 466, and the generator 434. The generated electrical energy can, for example, be fed into the described internal power grid or external power distribution grid.

[0107] As from the Figure 4 As can be seen, in the present embodiment, the generator 434 is arranged in front of the guide device 462. As already described, the generator 434 can be held or mounted "floating" in the turbine housing 456 by a support 458. The guide device 462 is integrated into the support 458 in this embodiment.

[0108] Furthermore, in the present case, the first heat exchanger 436 is arranged downstream of the guide device 462 in the flow direction 472. In particular, the thermal energy of the fuel gas flowing through the turbine device 430 is utilized by the first heat exchanger 436. The fluid refrigerant can be cooled in a simple manner. The first heat exchanger 436 can be held or mounted in the turbine housing 456 via a further support 458.

[0109] The Figure 5shows a diagram of an embodiment of a method according to the present application. The method is used in particular for operating a fuel gas storage system, as is described, for example, in Figure 2 or 3 The method can be carried out in particular under the control of a control device of the fuel gas storage system.

[0110] In a first step 501, a fuel gas is provided from a fuel gas distribution network through at least one fuel gas connection, as previously described.

[0111] In the next step 502, the provided fuel gas is compressed by at least one fuel gas compression arrangement, as previously described.

[0112] In step 503, the compressed fuel gas is stored in at least one fuel gas storage device, as previously described. Steps 501 to 503 are, in particular, steps of the storage process 507.

[0113] In step 504, fuel gas can be removed from the fuel gas storage.

[0114] Then, in step 505, the fuel gas taken from the fuel gas storage device is expanded by at least one expansion working machine, in particular a turbine device, at least one fuel gas expansion arrangement, as previously described.

[0115] In step 506, the expanded fuel gas is fed into the fuel gas distribution network through the fuel gas connection, as previously described. Steps 504 to 506 are, in particular, steps of the storage process 508. List of reference symbols

[0116] 100State-of-the-art fuel gas storage system 102Fuel gas distribution network 104Fuel gas compression arrangement, 106Fuel gas storage 108Fuel gas expansion arrangement 110Compressor 112Air cooler 114Compression stage 116Cooling device, heating device 118Control valve orExpansion valve 120 Gas preparation 122 Fuel gas connection 124 Storage connection 126 Fuel gas distribution network 200 Fuel gas storage system 202 Fuel gas distribution network 204 Fuel gas compression arrangement 206 Fuel gas storage 208 Fuel gas expansion arrangement 210 Compressor 222 Fuel gas connection 224 Storage connection 226 Fuel gas distribution network 230 Expansion working machine, in particular turbine device 300 Fuel gas storage system 304 Fuel gas compression arrangement 310 Compressor 322 Fuel gas connection 330 Expansion working machine, in particular turbine device 334 Generator 336 First heat exchanger 338 Second heat exchanger 340 Power grid 342 Refrigerant distribution network 344 First refrigerant storage 346Second refrigerant storage 348Control device 350Power distribution network 352Refrigeration circuit 430Expansion working machine, in particular turbine device 434Generator 436First heat exchanger 456Turbine casing 458Support 462Guide device 464Running device 466Turbine shaft 468Inlet 470Outlet 472Flow direction.

Claims

1. A fuel gas storage system (200, 300), comprising: - at least one fuel gas connection (222, 322) configured to provide a fuel gas from a fuel gas distribution network (202, 302), - at least one fuel gas compression arrangement (204, 304) configured to compress the supplied fuel gas, - at least one fuel gas storage tank (206, 306) configured to store the compressed fuel gas, - at least one fuel gas expansion arrangement (208, 308) configured to expand the fuel gas removed from the fuel gas store (206, 306), - wherein the fuel gas connection (222, 322) is configured to feed the expanded fuel gas into the fuel gas distribution network (202, 302), - wherein the fuel gas expansion arrangement (208, 308) comprises at least one expansion work machine (230, 330, 430), - wherein the expansion work machine (230, 330, 430) comprises at least one first heat exchanger (336, 436) configured to cool a fluid refrigerant, - wherein the fuel gas compression arrangement (204, 304) comprises at least one second heat exchanger (338.1, 338.2) configured to cool the fuel gas, and - the fuel gas storage system (200, 300) comprises at least one internal refrigerant distribution network (342) configured to supply the at least one second heat exchanger (338.1, 338.2) at least partly with the fluid refrigerant cooled by the first heat exchanger (336), characterized in that - the at least one second heat exchanger (338.1, 338.2) is arranged in the fuel gas compression arrangement (204, 304) in such a way that the provided fuel gas is cooled upstream the at least one compressor (310) of the fuel gas compression arrangement (204, 304).

2. The fuel gas storage system (200, 300) according to claim 1, characterized in that - the fuel gas is selected from the group comprising: natural gas, biogas and hydrogen.

3. The fuel gas storage system (200, 300) according to claim 1 or 2, characterized in that the expansion work machine (230, 330, 430) is a turbine device (230, 330, 430) and comprises at least one generator (334, 434) configured to generate electrical energy.

4. The fuel gas storage system (200, 300) according to claim 3, characterized in that the fuel gas storage system (200, 300) comprises an internal power network (340) configured to supply at least one electrical consumer (310, 348) of the fuel gas storage system (200, 300) at least partly with the electrical energy generated by the generator (334, 434).

5. The fuel gas storage system (200, 300) according to one of the previous claims, characterized in that - the second heat exchanger is configured to cool the fuel gas provided by the fuel gas connection to at least less than -10°C, preferably to less than -15°C, particularly preferably to at least -20°C.

6. The fuel gas storage system (200, 300) according to one of the previous claims, characterized in that - the fuel gas storage system (200, 300) comprises at least one first refrigerant storage (344) configured to store the fluid refrigerant cooled by the first heat exchanger (336).

7. The fuel gas storage system (200, 300) according to one of the previous claims, characterized in that the fuel gas storage system (200, 300) comprises at least one second refrigerant storage (346) configured to store the fluid refrigerant heated by the at least one second heat exchanger (338.1, 338.2).

8. A method for operating a fuel gas storage system (200, 300), in particular, a fuel gas storage system (200, 300) according to one of the previous claims, comprising: - providing, by means of at least one fuel gas connection (222, 322), a fuel gas from a fuel gas distribution network (202, 302), - compressing, by means of at least one fuel gas compression arrangement (204, 304), the provided fuel gas, - storing, by means of at least one fuel gas storage tank (206, 306), the compressed fuel gas, - expanding, by means of at least one expansion work machine (230, 330, 430) of at least one fuel gas expansion arrangement (208, 308), the fuel gas removed from the fuel gas accumulator (206, 306), and - feeding, by means of the fuel gas connection (222, 322), the expanded fuel gas into the fuel gas distribution network (202, 302), - wherein the fuel gas expansion arrangement (208, 308) comprises at least one expansion work machine (230, 330, 430), - cooling, by mean of a first heat exchanger (336, 436) of the expansion work machine (230, 330, 430), of a fluid refrigerant, - cooling, by means of at least one second heat exchanger (338.1, 338.2) of the fuel gas compression arrangement (204, 304) of the fuel gas, and - supplying, by means of an internal refrigerant distribution network (342) of the fuel gas storage system (200, 300), the at least one second heat exchanger (338.1, 338.2) at least partially with the fluid refrigerant cooled by the first heat exchanger (336), - wherein the at least one second heat exchanger (338.1, 338.2) is arranged in the fuel gas compression arrangement (204, 304) in such a way that the provided fuel gas is cooled upstream of the at least one compressor (310) of the fuel gas compression arrangement (204, 304).

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