Device and method for compressing a medium

Abstract

A device for compressing a medium is equipped with a compressor unit (2) for compressing a drive medium and with a pressure intensifier (13) operatively connected to the compressor unit, in which a drive piston (15) driven by the drive medium and a high-pressure piston (18a, 18b) cooperating with the drive piston (15) for compressing the medium to be compressed is arranged. According to the invention, hydrogen is used as the drive medium, and the compressor unit (2) comprises a hydrogen storage system (3a, 3b) which has a pressure vessel (4a, 4b) equipped with a metal hydride storage medium (7a, 7b) with at least one supply line (5a, 5b, 6a, 6b) for supplying and / or removing hydrogen into or from the pressure vessel (4a, 4b) and a heating device (8a, 8b) for heating the metal hydride storage medium (7a, 7b) in the pressure vessel (4a, 4b).

Description

[0001] The invention relates to a device for compressing a medium, comprising a compressor unit for compressing a drive medium and a pressure intensifier operatively connected to the compressor unit, in which a drive piston driven by the drive medium is arranged within a first cylinder and a high-pressure piston cooperating with the drive piston for compressing the medium to be compressed is arranged within a second cylinder, and a corresponding method.

[0002] Apparatus for compressing a medium using a working medium is known in various designs in the prior art. For example, WO 2019 / 145314 A1 describes a device for compressing a working medium in which a drive medium is compressed by means of a compressor and fed to a pressure intensifier. In the pressure intensifier, a first piston driven by the drive medium in a first cylinder acts on a second piston in a second cylinder, thereby compressing a working medium present in the second cylinder. In this device, the heat of the compressed working medium is used to heat the drive medium in order to increase the pressure in the first piston. The device is preferably used to compress gaseous hydrogen as the working medium to pressures between 100 bar and 1500 bar, with a gas, for example air, nitrogen, carbon dioxide, or a noble gas, being the preferred drive medium.

[0003] A disadvantage of such devices, which use a compressor to compress a medium, is that its operation, in addition to significant energy consumption, is associated with considerable noise emissions and unwanted vibrations, and also requires regular maintenance.

[0004] WO 2007 / 036651 A1 discloses a method for filling a pressure tank with a gaseous medium by applying a gaseous drive medium to a piston assembly. The drive medium is a cryogenically liquefied gas, which is vaporized and supplied to the piston assembly to build up pressure. This device eliminates the need for a compressor to compress the drive medium, but requires a liquefied gas for pressure generation, the provision of which involves considerable logistical effort and corresponding costs.

[0005] A device for compressing hydrogen is known from WO 2012 114 229 A1. The device comprises at least two metal hydride compression modules, each equipped with a cooling and heating system and connected to a hydrogen gas distribution system. Highly compressed hydrogen is produced in the metal hydride compression modules through a sequence of cooling, hydrogen supply, and subsequent heating. This highly compressed hydrogen can then be fed into the gas distribution system. A continuous supply of compressed hydrogen can be achieved by alternately operating the modules. This apparatus does not require a mechanical compressor but is limited to the compression of hydrogen gas.

[0006] The object of the present invention is therefore to create a device or method for compressing a medium that overcomes the disadvantages of the prior art.

[0007] This problem is solved by a device having the features of claim 1 and by a method having the features of claim 9. Advantageous embodiments of the invention are claimed in the dependent claims.

[0008] A device of the type and purpose mentioned above is characterized according to the invention in that hydrogen is used as the drive medium and the compressor unit has at least one hydrogen storage system which is equipped with at least one pressure vessel having at least one supply line for supplying and / or removing hydrogen, a metal hydride storage medium contained in the pressure vessel and a heating device for heating the metal hydride storage medium in the pressure vessel.

[0009] Hydrogen, the propellant gas, can be bound in large quantities in a metal hydride storage medium by chemisorption and extracted in a compressed state by the addition of thermal energy. Metal hydride storage systems are known per se. For example, WO 2020 / 207790 A1 describes a combined storage and compression system for hydrogen, which is used in particular for filling high-pressure hydrogen tanks. The system comprises a pressure vessel filled with a metal hydride storage medium, equipped with a cooling device and a heating device. By supplying hydrogen gas at a pressure of less than 30 bar while simultaneously cooling the storage system to ambient temperature or below, hydrogen is stored in the storage medium. By heating the storage medium to a temperature of up to 200°C, the hydrogen is compressed to a pressure of up to 800 bar and can thus be filled, for example, into vehicle tanks.

[0010] For example, the metal hydride storage medium of the device according to the invention belongs to one of two material classes, designated as AB2 materials and AB5 materials, respectively. In the case of an AB2 material, material A is, for example, titanium, which may be partially substituted with zirconium or another element, and material B may comprise a plurality of components selected from the group consisting of vanadium, manganese, iron, cobalt, and nickel or another element. In the case of an AB5 material, material A is, for example, lanthanum, which may be partially substituted with cerium, neodymium, and / or another element, and material B may be nickel, which may be partially substituted with at least one component or a plurality of components selected from the group consisting of cobalt, aluminum, manganese, and iron or another element.Preferably, the storage medium has a hydrogen storage capacity of at least 1.5 wt.% and absorbs hydrogen at a pressure preferably below 30 bar and a temperature preferably below 30°C. However, the present invention is not limited to these specific types of metal hydride storage media; rather, any storage medium capable of storing hydrogen by absorption and from which the stored hydrogen can be extracted by heating to a desired pressure can be used.

[0011] In the context of the present invention, the term "heating device" is understood to mean any device that can supply heat to the metal hydride storage medium. This includes, for example, an electric heater, a burner assembly, or a heat exchanger by means of which thermal contact with a heat transfer medium can be established. The heat transfer medium can be, for example, a process gas that is generated in the vicinity of the device according to the invention and is at a temperature at which it can at least contribute to heating the metal hydride storage medium, and in particular, a waste heat transporting medium. Heat generated during the operation of the device according to the invention or during the method according to the invention can also be used to heat the metal hydride storage medium, in particular the heat of compression of the medium being compressed.

[0012] The hydrogen, thermally compressed by heating the metal hydride storage unit, is then available as the driving medium for the pressure intensifier. The compressed hydrogen is fed to the drive piston of the pressure intensifier, whereby, from a flow engineering perspective (viewed in the direction of hydrogen flow), a buffer tank can be provided between the compressor unit and the pressure intensifier to compensate for pressure fluctuations.

[0013] The pressure intensifier has at least one drive cylinder with a drive piston, on which hydrogen acts as the drive medium, and at least one high-pressure piston cooperating with the drive piston to compress the medium to be compressed (e.g., nitrogen), which is contained in a high-pressure piston. The pressure p1 of the hydrogen acting on an area A AKThe force acting on the drive piston results in a force F1, which is transmitted to the high-pressure piston, for example via a piston rod. Since the system is static, the force F1 results in a counterforce F2 on the high-pressure piston, which acts on a surface A. HK of the high-pressure piston a pressure p2 with p2 = A AK / A HK The pressure p1 is caused by the pressure on the medium to be compressed. To achieve the highest possible pressure in the medium being compressed, the area A is... AK the area of ​​the drive piston is preferably larger than A HK of the high-pressure piston; preferably there is a ratio of A between the piston surfaces AK : A HK ≥ 2, especially preferred A AK : A HK ≥ 4. As mentioned above, the heat of compression of the medium in the high-pressure piston can be used to heat the metal hydride storage medium and / or the hydrogen supplied to the working piston after its compression.

[0014] After the work has been performed on the drive piston, the hydrogen is extracted and either circulated in a loop to be reabsorbed by the metal hydride storage medium after pressure release and cooling, or it is used for another purpose.

[0015] Since efficient hydrogen absorption requires the metal hydride storage medium to preferably have a temperature below 30°C, and particularly preferably between 5°C and 25°C, at least one cooling device is provided. This device can be located within the hydrogen storage system to cool the metal hydride storage medium and / or upstream of the hydrogen storage system in a supply line to cool the hydrogen supplied to the metal hydride storage medium. Such a cooling device is particularly advantageous when the hydrogen is recirculated, as it is previously heated during desorption or compression. In this case, a cooling device can preferably be located within the hydrogen storage system itself and / or in a flow path between the pressure intensifier and the hydrogen storage system.A heat exchanger, for example, serves as a cooling device, in which the drive medium is brought into thermal contact with a cooling medium, such as air, cooling water or a cryogenic medium, or an electric cooling device with a coolant circuit.

[0016] To achieve continuous compression of the drive medium, a preferred embodiment of the invention provides that the compressor unit comprises at least two alternately switchable hydrogen storage systems. Each hydrogen storage system can be switched between two operating modes: an absorption mode, in which the metal hydride storage medium absorbs and stores hydrogen, and a desorption mode, in which heat is supplied to the metal hydride storage medium, causing hydrogen to be driven out of the metal hydride storage medium and thus building up pressure in the respective pressure vessel. By alternating the operation of the at least two hydrogen storage systems, it can be ensured that at least one hydrogen storage system is always available to build up pressure at the pressure intensifier.Particularly efficient operation can be achieved by thermally connecting the hydrogen storage systems to each other using heat pumps in such a way that the heat required for desorption from one hydrogen storage system can be at least partially taken from another hydrogen storage system that is operating in absorption mode.

[0017] Since the pressure of the hydrogen that can be generated in the compressor unit depends on the temperature of the metal hydride storage medium during the desorption of the hydrogen, the compressor unit is preferably equipped with a control device by means of which the power of the heating device can be controlled as a function of a desired setpoint pressure at the pressure intensifier.

[0018] Preferably, the pressure intensifier can be connected to a pressure-resistant reservoir in a flow-through connection, in which hydrogen is stored at a pressure corresponding to the drive pressure of the pressure intensifier. When required, the flow connection between the reservoir and the pressure intensifier is established, for example, by opening a valve, and hydrogen from the reservoir is supplied directly to the drive cylinder of the pressure intensifier. This particularly enables a cold start of the device according to the invention. Preferably, it is then ensured, for example, by keeping the valve open, that the reservoir is refilled with hydrogen from the compressor unit during operation of the device.

[0019] The compressor unit and pressure intensifier are preferably integrated in a closed circuit for the drive medium. In this configuration, the hydrogen is returned to the compressor unit after performing its work at the pressure intensifier. For this purpose, the hydrogen, expanded and cooled, is brought into contact with the metal hydride storage medium when the hydrogen storage system is in absorption mode. It can be temporarily stored in a reservoir (also referred to here as an "expansion reservoir") before being fed back into the compressor unit's metal hydride storage medium under pressure control.

[0020] To enable continuous compression of the medium to be compressed, the pressure intensifier is preferably equipped with at least two high-pressure pistons, each operatively connected to a drive piston, which can be operated alternately. For example, this is a double-chamber pressure intensifier in which the drive gas acts alternately on two opposing working surfaces of a reciprocating drive piston, each of which is operatively connected in both directions to a high-pressure piston. Such pressure intensifiers are known and are described, for example, in EP 2 610 490 A2 or EP 2 136 085 A2.

[0021] The object of the invention is also achieved by a method with the features of claim 9.

[0022] In the inventive method for compressing a medium, a drive medium is compressed in a compressor unit, and the compressed drive medium is fed to a pressure intensifier, in which the pressure of the drive medium is transferred to a drive piston and from there to a high-pressure piston for compressing the medium to be compressed. According to the device described above, the compressor unit comprises at least one hydrogen storage system, which is equipped with at least one pressure vessel having at least one inlet for supplying and / or removing hydrogen, a metal hydride storage medium contained in the pressure vessel, and a heating device for heating the metal hydride storage medium in the pressure vessel.The metal hydride storage medium stores hydrogen, which is supplied at a low temperature T1 (e.g., T1 < 30°C) and a low pressure p1 (e.g., p < 30 bar) and is absorbed by the metal hydride storage medium under these conditions. To build up pressure, the hydrogen stored in the metal hydride storage medium is heated to a temperature T2 (T2 > T1), causing it to desorb and form a compressed hydrogen atmosphere with a pressure of p2 (p2 > p1) in the pressure vessel. The compressed hydrogen from the pressure vessel is then supplied as the driving medium to the drive piston of the pressure intensifier. The pressure is transferred to the high-pressure piston, thus compressing the medium to be compressed.

[0023] The method according to the invention thus makes use of the property of certain metal hydride storage media, in particular the AB2 or AB5 type metal hydride storage media described above, which can absorb and permanently store large quantities of hydrogen and from which the stored hydrogen can be extracted by heating the storage medium to high pressure. In contrast to the prior art, which uses conventional, electrically operated compressors, the invention thus uses exclusively thermal energy for the compression of the medium. The thermal energy can be of any origin. For example, waste heat generated in the vicinity of a device according to the invention can be used.

[0024] During desorption, the temperature T2, to which the metal hydride storage system is heated by the heating device, determines the pressure p2 of the hydrogen in the pressure vessel of the hydrogen storage system, which essentially corresponds to the pressure of the hydrogen at the drive piston of the pressure intensifier. Preferably, the pressure p2 of the hydrogen at the drive piston is at least 10 bar, more preferably 50 bar, and particularly preferably at least 100 bar. In the pressure intensifier, the drive medium acts on an area A in the manner described above. AK of the drive piston and an area A HK of the high-pressure piston on the medium to be compressed, and the resulting working pressure in the medium to be compressed is of the ratio A AK / A HKThis depends on the surface area. Through the interaction of the metal hydride storage medium and the pressure intensifier, pressures of over 300 bar can be achieved in the medium to be compressed by moderately heating the hydrogen to a temperature T2 of, for example, between 100°C and 200°C. In this way, a technical gas, such as nitrogen, oxygen, carbon dioxide, or a noble gas, can be brought to a pressure with minimal effort that corresponds to the usual filling pressure of a container, for example, a compressed gas cylinder or a cylinder bundle, i.e., for example, 200 bar or 300 bar.

[0025] Preferably, the hydrogen used as the drive medium is circulated. For this purpose, after performing its work at the drive piston of the pressure intensifier, it is depressurized to a pressure p1 with p1 < p2 of, for example, less than 10 bar, preferably less than 5 bar, returned to the compressor unit, and cooled in this unit or upstream of it to a temperature T1 with T1 < T2 of preferably less than 30°C, preferably between 0°C and 25°C, for example in heat exchange with a coolant of a cooling circuit.

[0026] Advantageously, the compressor unit comprises at least two hydrogen storage systems that operate alternately in a first operating mode of hydrogen absorption and a second operating mode of hydrogen desorption. This allows, in particular, a continuous pressure build-up in the compressor unit. The heat required for desorption can, for example, be at least partially extracted by means of a heat pump from a hydrogen storage system operating in absorption mode, thereby cooling the metal hydride storage medium of that system. Each of the hydrogen storage systems can be equipped with one or more pressure vessels filled with the metal hydride storage medium.

[0027] The device and method according to the invention are particularly suitable for compressing a gaseous medium, for example air, nitrogen, oxygen, carbon dioxide, argon or any other noble gas or a mixture of the gases mentioned; however, they are not limited to this application.

[0028] An embodiment of the invention will be explained in more detail with reference to the drawing. The only drawing ( Fig. Figure 1) schematically shows a device according to the invention for compressing a medium.

[0029] The device 1 is used in particular for compressing a gas, for example nitrogen, oxygen, carbon dioxide, a noble gas, or a mixture of several of these gases. The compression is carried out, for example, to a pressure corresponding to the typical filling pressure of a container for transporting and / or storing such gases or gas mixtures, such as a compressed gas cylinder or a cylinder bundle, i.e., for example, 200 bar to 300 bar; however, depending on the application, lower or higher pressures may also be required.

[0030] The device 1 comprises a compressor unit 2, which has several, in the exemplary embodiment two, hydrogen storage systems 3a, 3b for compressing hydrogen, which can be operated alternately in the manner described in more detail below. The hydrogen storage systems 3a, 3b, which are preferably of identical construction, are thermal metal hydride compressors, such as those described, for example, in WO 2020 / 207790 A1, to which explicit reference is made here. Each hydrogen storage system 3a, 3b has at least one pressure vessel 4a, 4b, each equipped with an inlet 5a, 5b and an outlet 6a, 6b for gaseous hydrogen. A storage medium 7a, 7b consisting of a metal hydride is present in each pressure vessel 4a, 4b, for example a storage medium of type AB2 or AB5 of the type described above.

[0031] Furthermore, each of the hydrogen storage systems 3a, 3b has a heating device 8a, 8b for heating the respective storage medium 7a, 7b. The heating devices 8a, 8b can be, for example, electric heating devices or heat exchangers in which the respective storage medium 7a, 7b is brought into thermal contact with a warm medium, such as a process gas or a heat exchanger medium that dissipates waste heat from a process. In general, the use of waste heat is advantageous.

[0032] Each of the lines 5a, 5b, 6a, 6b is provided with an electronically controlled shut-off valve 9a, 9b, 10a, 10b, by means of which the flow of hydrogen through the respective line 5a, 5b, 6a, 6b can be regulated. Furthermore, a cooling device or a group of cooling devices 11a, 11b can be provided, by means of which the temperature of the hydrogen supplied to the hydrogen storage system 3a, 3b can be cooled to a value that is advantageous for the absorption of the hydrogen in the respective storage medium 7a, 7b. These cooling devices 11a, 11b can, for example, be arranged in the lines 5a, 5b and / or in one of the lines 31, 34, as shown here, and / or they can be part of the respective hydrogen storage system 3a, 3b and cool the storage medium 7a, 7b during the absorption of the hydrogen.

[0033] The hydrogen storage systems 3a and 3b can be thermally coupled via a heat pump 12, which, during alternating operation of the hydrogen storage systems 3a and 3b, allows an exchange of thermal energy between them. The heat pump 12 can also be used in addition to, or instead of, the heating systems 8a and 8b and / or the cooling systems 11a and 11b.

[0034] The hydrogen compressed in the compressor unit 2 is used to drive a pressure intensifier 13 (also called a pressure converter or pressure booster). In the design described here, the pressure intensifier 13 is a double-chamber pressure intensifier in which a drive piston 15 arranged in a first cylinder 14 is rigidly connected via an axially movable piston rod 16 to two high-pressure pistons 18a, 18b, each arranged in a high-pressure cylinder 17a, 17b. Working volumes 19a, 19b are provided on both sides of the drive piston 15 in the cylinder 14, each acting on one of two opposing working surfaces 20a, 20b of the drive piston 15. The high-pressure cylinders 17a, 17b have working volumes 22a, 22b on an effective surface 21a, 21b opposite the piston rod 16, each of which is intended for filling with a gas to be compressed.In a manner known per se, the effective surfaces 21a, 21b on the high-pressure pistons 18a, 18b are preferably designed to be smaller than the working surfaces 20a, 20b on the drive piston 15 in order to increase the pressure in the respective effective volume 22a, 22b; for example, the ratio of effective surface 21a, 21b to working surface 20a, 20b is between 1:2 and 1:4. However, the invention is not limited to a pressure increase at the pressure intensifier; rather, it is conceivable in some cases that the ratio of effective surface to working surface can also be larger, for example 1:1 or higher.

[0035] Furthermore, other designs of pressure intensifiers can also be used within the scope of the invention, for example, pressure intensifiers in which a working piston interacts with only one high-pressure piston, or arrangements in which a plurality of working pistons interact with a plurality of high-pressure pistons. Several pressure intensifiers 13 connected in parallel can also be used.

[0036] The hydrogen outlets 6a and 6b, leading from the hydrogen storage systems 3a and 3b, connect to a high-pressure line 24, which empties into a buffer tank 25. From the buffer tank 25, another high-pressure line 26, which can be closed by a valve 23, leads to a junction 27. At the junction 27, the high-pressure line 26 splits into two branch lines 28a and 28b, each providing a flow connection to a working volume 19a and 19b, respectively. A line 30a branches off from branch line 28a at an electronically controlled three-way valve 29a, and a line 30b branches off from branch line 28b at an electronically controlled three-way valve 29b. Lines 30a and 30b connect to a line 31, which empties into an expansion tank 32. From the expansion tank 32, a line 34 equipped with a pressure regulator 33 leads to the hydrogen supply lines 5a, 5b of the compressor unit 2.

[0037] The buffer tank 25 is connected via a line 36 to a high-pressure vessel 37, for example, a hydrogen-filled compressed gas cylinder, a cylinder bundle, or a pressure tank. The high-pressure vessel 37 is also connected via a line 38 to the expansion vessel 32. Lines 36 and 38 can be opened and closed by means of electronically controlled shut-off valves 39 and 40.

[0038] The working volumes 22a, 22b are integrated into gas lines 41, 42, in which a medium to be compressed, for example a gas such as nitrogen, oxygen, a noble gas, or carbon dioxide, is conveyed. Check valves 43a, 43b; 44a, 44b are arranged upstream and downstream of the respective working volumes 22a, 22b in the gas lines 41, 42. The compressed gas is discharged via a discharge port 45 and supplied for further use; for example, the compressed gas is filled into pressurized gas containers in a filling plant (not shown here). Furthermore, the gas lines 41, 42 upstream of the arrangement shown here can be supplied from a common source, for example a pipeline or a tank, which, however, is not shown here for the sake of clarity.

[0039] In the operation of device 1, hydrogen is circulated and used as the driving medium of the pressure intensifier 13. For this purpose, the hydrogen storage systems 3a, 3b are alternately operated in the absorption and desorption states by means of a control unit not shown here.

[0040] During absorption operation, hydrogen is supplied to the storage medium 7a, 7b in the respective pressure vessel 4a, 4b at a pressure preferably below 30 bar and a temperature of, for example, between 5°C and 25°C. The hydrogen is stored in the crystal lattice of the metal hydride.

[0041] During desorption, a heat flow is supplied to the storage medium 7a, 7b, causing the hydrogen to be driven out of the crystal lattice of the storage medium 7a, 7b and accumulate in the pressure vessel 4a, 4b under high pressure. The pressure experienced by the hydrogen can be freely adjusted and depends solely on the temperature to which the storage medium 7a, 7b is heated.

[0042] The following considers the case where hydrogen storage system 3a is used for absorption and hydrogen storage system 3b for desorption. In this case, valves 9a and 10b are open, and valves 9b and 10a are closed. The hydrogen, which is present in hydrogen storage system 3b at a pressure of, for example, 100 bar after heating the storage medium 7b, flows via outlet 6b and high-pressure line 24 into the buffer tank 25, which serves only to compensate for pressure fluctuations, and out of it via high-pressure line 26. At the junction 27, the hydrogen flows into one of the branch lines 28a or 28b, which is determined by the corresponding switching of the three-way valves 29a and 29b. For example, switching the three-way valve 29a establishes a flow connection between high-pressure line 26 and the working volume 19a of the pressure intensifier 13.In this case, the hydrogen flows into the working volume 19a and, under the influence of the gas pressure, drives the working piston 15 – and simultaneously the high-pressure piston 18b – towards the effective volume 22b. The gas present in the effective volume 22b is thereby compressed, whereby, due to the area ratio of the working area 20a and the effective area 21b, the resulting pressure in the effective volume 22b can be considerably higher, for example by a factor of 2 to 4, than the pressure in the working volume 19a. To achieve a desired pressure of the gas to be compressed in the effective volume 22b, the temperature to which the metal hydride storage medium 7b is heated is adjusted. The corresponding setting is made with a control device not shown here, by means of which the valves 9a, 9b, 10a, 10b, 29a, 29b, 39, 40 as well as the heating devices 8a, 8b, the cooling devices 11a, 11b and the heat pump 12 can also be controlled.

[0043] The compressed gas then flows out via lines 42 and 45. Simultaneously, a flow connection exists between the working volume 19b and the expansion vessel 32 due to a corresponding setting on the three-way valve 29b, and hydrogen from the working volume 19b flows into the expansion vessel 32 under pressure relief.

[0044] Once the maximum piston stroke is reached, i.e., maximum pressure is achieved in the working volume 22b, the three-way valves 29a and 29b are adjusted to establish a flow connection between the high-pressure line 27 and the working volume 19b. The flow connection between the high-pressure line 27 and the working volume 19a is closed, and simultaneously a flow connection is established between the working volume 19a and the expansion tank 32. Under the pressure of the hydrogen flowing into the working volume 19b, the working piston 15—and with it, the piston rod 16 and the high-pressure piston 18a—now moves in the opposite direction, i.e., towards the working volume 22a, compressing the gas present there. The hydrogen from the working volume 19a flows into the expansion tank 32.Due to the design of the pressure intensifier 13 as a double-chamber pressure intensifier, a continuous conveyance of compressed gas via the outlet 45 is achieved in this way.

[0045] Once the hydrogen supply in storage medium 7b is exhausted, the hydrogen storage system 3b switches to absorption mode. For this, the heating of storage medium 7b is stopped, and the storage medium 7b is cooled, if necessary, by an integrated cooling device or by the addition of cold hydrogen. The shut-off valve 10b is closed, and the shut-off valve 9b is opened. This allows hydrogen to flow from the expansion tank 32 into the hydrogen storage system 3b, where it is available for re-compression. The pressure control valve 33 ensures a constant pressure of, for example, 5 bar for the hydrogen supplied to the hydrogen storage system 3b. Simultaneously, the hydrogen storage system 3a is switched to desorption mode by closing the shut-off valve 9a, opening the shut-off valve 10a, and starting the heating device 8a.

[0046] By operating the hydrogen storage systems 3a, 3b alternately, hydrogen is continuously pumped in a cycle from the compressor unit 2 to the pressure intensifier 13 and back from this to the compressor unit 2, thereby continuously performing compression work on the pressure intensifier 13.

[0047] The high-pressure vessel 37 serves to accelerate start-up by supplying hydrogen to the buffer vessel 25 via shut-off valve 39. The high-pressure vessel 37 can then be refilled during operation by overflowing from the buffer vessel 25. The high-pressure vessel 37 can also be used to compensate for any pressure drop below the required minimum in the expansion vessel 32 by supplying hydrogen via shut-off valve 40.

[0048] In the embodiment shown here, a maintenance line 45 is also provided on the expansion tank 32, via which losses in the hydrogen circuit can be compensated or the circuit as a whole can be filled or emptied. Reference symbol list 1 Device 2 compressor units 3a, 3b Hydrogen storage system 4a, 4b Pressure vessel 5a, 5b Supply line 6a, 6b Expulsion 7a, 7b Storage medium 8a, 8b Heating equipment 9a, 9b shut-off valve 10a, 10b shut-off valve 11a, 11b Cooling equipment 12 Heat pump 13 print translators 14 cylinders 15 drive pistons 16 Piston rod 17a, 17b High-pressure cylinders 18a, 18b High-pressure piston 19a, 19b Work volume 20a, 20b Work area 21a, 21b Effective area 22a, 22b Effective volume 23 Valve 24 High-pressure line 25 buffer tanks 26 High-pressure line 27 Branching point 28a, 28b Branch Management 29a, 29b Three-way valve 30a, 30b Line 31 Management 32 relaxation containers 33 pressure regulators 34 Management 35 - 36 Management 37 high-pressure tanks 38 Management 39 shut-off valve 40 shut-off valve 41 Gas pipeline 42 Gas pipeline 43a, 43b Check valve 44a, 44b Check valve 45 Detoxification 46 Maintenance Management

Claims

[1] Device for compressing a medium, comprising a compressor unit (2) for compressing a drive medium and a pressure intensifier (13) operatively connected to the compressor unit (2), in which a drive piston (15) driven by the drive medium is arranged within a first cylinder (14) and a high-pressure piston (18a, 18b) cooperating with the drive piston for compressing the medium to be compressed is arranged within a second cylinder (17a, 17b), characterized by, that hydrogen is used as the propulsion medium and the compressor unit (2) has at least one hydrogen storage system (3a, 3b) which is equipped with at least one pressure vessel (4a, 4b) having at least one supply line (5a, 5b, 6a, 6b) for supplying and / or removing hydrogen, a metal hydride storage medium (7a, 7b) contained in the pressure vessel (4a, 4b) and a heating device (8a, 8b, 12) for heating the metal hydride storage medium (7a, 7b) in the pressure vessel (4a, 4b). [2] Device according to claim 1, characterized by , that the compressor unit (2) is equipped with a cooling device (11a, 11b) for cooling the metal hydride storage medium (7a, 7b) and / or the hydrogen supplied to the metal hydride storage medium (7a, 7b). [3] Device according to claim 1 or 2, characterized by, that the compressor unit (2) comprises at least two hydrogen storage systems (3a, 3b) that can be switched alternately between an absorption operating mode and a desorption operating mode. [4] Device according to any one of the preceding claims, characterized by , that the compressor unit (2) is equipped with a control device by means of which the power of the heating device (8a, 8b, 12) of the at least one hydrogen storage system (3a, 3b) can be controlled as a function of a desired setpoint pressure at the pressure intensifier (13). [5] Device according to any one of the preceding claims, characterized by , that an area A exposed to the driving medium AK (20a, 20b) of the drive piston (15) larger, preferably more than twice as large, as an area A acting on the medium to be compressed HK (21a, 21b) of the high-pressure piston (18a, 18b). [6] Device according to any one of the preceding claims, characterized by, that the pressure intensifier (13) is in flow communication with a storage container (37), from which hydrogen can be supplied to the pressure intensifier (13) at a predetermined pressure as required. [7] Device according to any one of the preceding claims, characterized by , that the compressor unit (2) and the pressure intensifier (13) are integrated in a closed circuit for the drive medium. [8] Device according to any one of the preceding claims, characterized by , that the pressure intensifier (13) is equipped with at least two high-pressure pistons (18a, 18b) each operatively connected to a drive piston (15), which can be operated alternately. [9] Method for compressing a medium in which a drive medium is compressed in a compressor unit (2) and the compressed drive medium is supplied to a pressure intensifier (13) in which the pressure of the drive medium is transferred to a drive piston (15) and from this to a high-pressure piston (18a, 18b) for compressing the medium to be compressed, characterized by, that the compressor unit (2) comprises at least one hydrogen storage system (3a, 3b) which is equipped with at least one pressure vessel (4a, 4b) having at least one supply line (5a, 5b, 6a, 6b) for supplying and / or removing hydrogen, a metal hydride storage medium (7a, 7b) contained in the pressure vessel (4a, 4b) and a heating device (8a, 8b, 12) for heating the metal hydride storage medium in the pressure vessel (4a, 4b), and that, in order to build up pressure in the metal hydride storage medium (7a, 7b), hydrogen stored in the metal hydride storage medium (7a, 7b) is heated to a temperature T2 by heating the metal hydride storage medium (7a, 7b), thereby desorbing and forming a compressed hydrogen atmosphere with a pressure of p2 in the pressure vessel (4a, 4b), and the compressed hydrogen is then released from the pressure vessel (4a, 4b) as The drive medium is supplied to the drive piston (15) of the pressure intensifier (13). [10] Method according to claim 9, characterized by, that the temperature T2 is selected such that the hydrogen supplied to the pressure intensifier (13) has a pressure of at least 10 bar, preferably at least p2=50 bar, particularly preferably at least p2=100 bar. [11] Method according to claim 9 or 10, characterized by , that the drive medium is circulated and, after performing its work at the drive piston (15) of the pressure intensifier (13), is cooled to a temperature T1 with T1 <T2 gekühlt und auf einen Druck p1 mit p1<p2 entspannt, dem Wasserstoff-Speichersystem (3a, 3b) zugeführt und dort vom Metallhydrid-Speichermedium (7a, 7b) absorbiert wird. [12] Method according to claim 11, characterized by , that the temperature T1 is between 0°C and 30°C and the pressure p1 is between 1 bar and 30 bar. [13] Method according to any one of claims 9 to 12, characterized by, that the compressor unit (2) comprises at least two hydrogen storage systems (3a, 3b) which are operated alternately in a first operating mode of absorption of hydrogen and a second operating mode of desorption of hydrogen. [14] Method according to any one of claims 9 to 13, characterized by that the medium to be compressed is a gas, in particular air, nitrogen, oxygen, carbon dioxide, a noble gas or a mixture of the aforementioned gases.

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