System for compressing, storing and providing gas and corresponding method

Abstract

The invention relates to a system (100) for compressing, storing and providing gas, in particular hydrogen, having a compressing device (140), a storage device (120), an expansion machine (26) and a refrigeration machine (32), in particular an absorption-type refrigeration machine, wherein the system (100) is configured (a) to compress received gas by means of the compressing device (140), in particular in multiple stages, and (b) to store the compressed gas in the storage device (120), wherein the system (100) is configured to refrigerate the compressing device (140) using the refrigeration machine (32) and the expansion machine (26).

Description

[0001] Description

[0002] Plant for compressing, storing and supplying gas and corresponding process

[0003] The invention relates to a system for compressing, storing and providing gas, in particular hydrogen, as well as a method for operating such a system, e.g. a hydrogen filling station.

[0004] Hydrogen, which is used, for example, as a fuel for vehicles, can be provided via so-called hydrogen filling stations. Two types of hydrogen filling stations can be distinguished. The first type uses liquid hydrogen as a source and compresses the hydrogen into a liquid, i.e., in liquid form. The second type, however, has a gaseous hydrogen source and compresses the hydrogen into a gaseous state, i.e., the hydrogen is at least initially obtained in a gaseous state and then compressed into a gaseous state. In addition, two basic system areas can be distinguished at a hydrogen filling station. The first system area concerns the compression of the hydrogen, its storage, as well as its conditioning and cooling. The second system area comprises a

[0005] Hydrogen dispenser and the associated refueling equipment such as breakaway and refueling couplings and the refueling hose.

[0006] Second-type hydrogen filling stations or similar facilities typically require significant amounts of energy to dissipate or cool the heat released during compression. Against this backdrop, the challenge is to make the compression of gas and the operation of such a facility as energy-efficient as possible.

[0007] Disclosure of the invention

[0008] This object is achieved by a system for compressing, storing, and providing gas, as well as a method for operating such a system, having the features of the independent patent claims. Preferred embodiments are the subject of the dependent patent claims and the following description. Advantages of the invention

[0009] The invention relates to the compression, storage, and provision of gas, as well as to corresponding systems and their operation. As mentioned at the beginning, hydrogen filling stations are particularly suitable as such systems. The invention will therefore be described below with particular reference to hydrogen filling stations; however, the principle can also be applied to other systems for compressing gas, e.g., with other types of gases, or for other purposes.

[0010] As mentioned, two types of hydrogen refueling stations can be distinguished. The first type uses liquid hydrogen as a source and compresses the hydrogen into a liquid state, i.e., in liquid form. The second type, however, uses a gaseous hydrogen source, i.e., it receives the hydrogen in gaseous form and compresses it into a gaseous state. The present invention deals with the second type of hydrogen refueling station, or more generally, with the compression, storage, and provision of gas.

[0011] A hydrogen refueling station can be divided into two basic system areas. The first system area concerns the compression of hydrogen, its storage, as well as its conditioning and cooling. The second system area comprises the provision for the specific use, e.g., a hydrogen dispenser and the associated refueling equipment such as a breakaway and refueling coupling, as well as the refueling hose. The present invention relates in particular to the first system area, and therein in particular to the compression, but also storage and, if applicable,

[0012] Conditioning and cooling of gas.

[0013] At a second type of hydrogen filling station, hydrogen is usually compressed in several stages (typically interstage and cylinder jacket cooled) to up to 1000 bar and stored in medium and / or high pressure banks at, for example, between 500 and 1000 bar. When refueling a vehicle at the dispenser of the hydrogen filling station, the gas is usually specifically pre-conditioned with regard to pressure and mass flow using a so-called pressure ramp controller. In order to refuel hydrogen-powered vehicles with hydrogen in accordance with current standards (e.g. SAE J2601, JPEC-S0003, Phryde Protocol or CEP Protocol), it is generally necessary to pre-cool the gas (hydrogen) to temperatures of up to 233.15 K (or -40°C) before refueling. In the relevant temperature ranges, gaseous hydrogen warms up as a result of isenthalpic expansion due to the negative Joule-Thomson effect.Since a pressure gradient (this is again an isenthalpic expansion) occurs during refueling due to overflow between the filling station infrastructure and the vehicle tank, hydrogen filling stations are typically equipped with cooling systems, which usually consist of a compression refrigeration machine and a hydrogen or gas heat exchanger, whereby different cold storage concepts are also used.

[0014] The intermediate stages mentioned above (one stage corresponds, for example, to a cylinder with a given pressure level at a given compression ratio) can be cooled to a temperature close to ambient temperature using either water / air or water / air mixture heat exchangers. Cooling can also be achieved using spray-assisted cooling with water / air recoolers (provided sufficient water of sufficient quality is available), which can thus be kept at wet bulb temperature, or, for example, through the use of so-called chillers. These chillers typically comprise compression refrigeration machines that maintain a cold water circuit that is integrated into the interstage cooling circuit and therefore cools it.

[0015] Cooling the heat released during refueling of a hydrogen-powered vehicle at the respective expansion point (e.g., at the pressure ramp regulator) as well as the heat released during multi-stage compression of gaseous hydrogen requires considerable amounts of energy. Depending on the system, different target hydrogen temperatures may be required. This requires additional energy resources and therefore massively increases the specific energy consumption of the system, such as the hydrogen filling station. Globally, a rise in temperature is being observed due to climate change, which places additional demands on the thermal resilience of hydrogen filling stations, as it can lead to increased wear and tear.Against this background, it is proposed that in a system for compressing, storing and providing gas, in particular hydrogen, which system has a compression device and a storage device and is designed to compress the resulting gas by means of the compression device, in particular in several stages, and to store the compressed gas in the storage device, an expansion machine and a refrigeration machine, in particular an absorption refrigeration machine, be provided. The system is then also designed to cool the compression device, e.g. a multi-stage piston compressor, using the refrigeration machine and the expansion machine. Any type of device or machine that cools or can cool gas by expansion can be considered as an expansion machine. In the case of an absorption refrigeration machine, the refrigeration machine can, for example, operate with ammonia as the working medium (coolant) in the desired temperature range.The use of an expansion machine and a chiller allows for particularly efficient cooling of the compression unit or compressor, especially during different operating phases of the system. An adsorption chiller could also be used instead of an absorption chiller.

[0016] Preferably, the system further comprises a first cold storage device (e.g. a cold accumulator) and is configured to conduct the stored gas from the storage device via the expansion machine and subsequently the first cold storage device. Since the gas is cooled by the expansion, the first cold storage device or a coolant therein can be cooled in this way by means of the expansion machine. Via a coolant flow from the first cold storage device to one or more housing components of the compression device, in particular inlets for the gas and / or a drive, these housing components can then be cooled, for example. Since the first cold storage device is cooled by means of the expansion machine, the compression device or at least parts thereof can also be cooled in this way by means of the expansion machine.

[0017] Preferably, the system further comprises a second cold storage device and is configured to guide the stored gas from the storage device directly (i.e. not via a further machine such as the expansion machine; however, any valves and the like are left out here) via the second cold storage device.

[0018] The system can then also be configured to cool the gas by means of the first cold storage device to a different, in particular lower, average temperature than by means of the second cold storage device, and in particular to mix (or combine) gas streams downstream of the first cold storage device and the second cold storage device in order to provide the gas at a desired temperature, e.g., at a supply device such as a dispenser. This second cold storage device is preferably cooled by a coolant stream from the refrigeration machine, in particular from a cold outlet of the refrigeration machine.

[0019] The system is advantageously also configured to route the stored gas from the storage device, as required, either via the expansion machine and subsequently the first cold storage device, directly via the second cold storage device, or via the expansion machine and subsequently the first cold storage device and also directly via the second cold storage device, e.g., in a desired distribution ratio, and to make it available for use, in particular via the system's supply device. This allows the temperature of the gas to be adjusted as required.

[0020] Preferably, the system is configured to further cool the one or more housing components of the compression device via a coolant flow from the refrigeration machine, in particular by admixing coolant into the coolant flow of the first cold storage device, further in particular after cooling the second cold storage device. This admixture allows for greater variability and precision in cooling.

[0021] Particularly preferably, the compression device has a plurality of compressor stages for multi-stage compression of the gas; this can be, for example, a plurality of stages in the form of a multi-stage piston compressor. The system is then configured to cool gas between two compressor stages and / or between a final compressor stage and the storage device via a coolant flow from the refrigeration machine, which is fed in the return line of the refrigeration machine, in particular to a warm inlet of the refrigeration machine. For this purpose, suitable heat exchangers can be provided after each compressor stage, for example. This allows the temperature level at the inlet of the refrigeration machine to be kept high in order to achieve high efficiency.

[0022] When the system is commissioned, the chiller can be temporarily forced-heated to cool the first cold storage device. Furthermore, when the system is commissioned, the second cold storage device can be cooled by filling it with water from an external storage tank or into the storage device or one or more storage banks there. In this way, an operating state can be established.

[0023] A particular advantage of the proposed concept is the increased efficiency of the entire system and the extension of the system's service life. Consequently, significantly less electrical energy is required for cooling, but is partly generated by the expansion machine, which significantly reduces the system's ecological footprint (no refrigerants with high GWP, "Global Warming Potential", lower electricity consumption) and significantly lowers the system's specific energy consumption. This represents a major advantage for the end customer but also for the hydrogen sector as a whole. A further advantage is the extended service life of the compression device, for example, of gas cylinder-piston units (especially the stage seals made of polymers), as these can be cooled to optimal temperatures (e.g., to below 50°C gas inlet temperature in the respective cylinder stage).

[0024] At the same time, cold is generated, thus providing optimized cooling for the drive unit of the compression system. By using a chiller and an expansion machine, thermal load fluctuations in the system can be very effectively covered by randomly distributed, stochastic refueling profiles, with fluctuating ambient temperatures and variable compressor speeds and running times. This in turn offers the advantage of constant target temperatures for the components and media to be cooled. The invention is schematically illustrated in the drawing using an exemplary embodiment and is described below with reference to the drawing.

[0025] Short description of the drawing

[0026] Figure 1 shows schematically a system according to the invention in a preferred embodiment.

[0027] Detailed description of the drawing

[0028] Figure 1 schematically illustrates a preferred embodiment of a system 100 according to the invention, by means of which a method according to the invention can also be carried out. In particular, a concrete example of a system 100 designed as a hydrogen filling station with a piston compressor as the compression device 140 and a storage device 120 comprising, by way of example, three storage banks 20, 21, 22 is shown. A drive 41 of the piston compressor 140 can be designed, for example, mechanically, hydraulically, or pneumatically.

[0029] In the case illustrated in Figure 1 of refueling a vehicle 200 with a running compressor (compression device 140) and a higher hydrogen mass flow than the compressed hydrogen mass flow, the system 100 is supplied with hydrogen, shown here as stream a, from a source 110 such as an electrolysis plant, a pipeline, a trailer, or a comparable system. It is understood that, as a rule, various components or installations may be provided or even necessary between the source 110 and the piston compressor 140 (e.g., input buffers, pressure regulators, sensors, etc.), which, however, are not shown here and are not further relevant to the present invention.

[0030] The resulting hydrogen a then enters the multi-stage piston compressor 140, or a first piston unit 2 there, via a check valve 1, for example. The compressor, or the piston compressor 140 itself, can have four stages (as shown here), but also more or fewer. These stages represent, for example, gas cylinder-piston units 2, 6, 10, and 14, which each have check valves 1, 3, 5, 7, 9, 11, 13, and 15 at the gas-side inlet and outlet.

[0031] The gas cylinder-piston units can also be double-acting.

[0032] Between those check valves which are located between the stages (check valves 3, 5, 7, 9, 11, 13) but also after the last stage (check valve 15; in special cases, e.g., also check valve 1), the hydrogen is cooled by means of heat exchangers 4, 8, 12, 16 to a temperature which is compatible with the sealing systems of the gas cylinder-piston units and / or other components such as those of the storage banks 20, 21, 22 of the storage device 120, e.g., to below 50°C.

[0033] After cooling and compression, the hydrogen, here stream b, enters the storage bank 20, 21, 22 to be filled, e.g. via check valves 17, 18, 19. The number of storage banks can vary depending on the plant or filling station layout.

[0034] A cascade refueling of the vehicle 200 is then controlled, for example, by opening and closing the valves 23, 24 and 25 (which are assigned to the storage banks 20, 21, 22).

[0035] When the gas leaves the active storage bank, it flows as stream c either through an expansion machine 26, which cools the gas and at the same time regulates the pressure ramp using a generator brake (the electricity generated in this way can, for example, be fed into the power grid or used on-site), or the gas flows as stream d, for example through a bypass valve 29, which also acts as a pressure ramp regulator and is immediately cooled in a second cold storage device 30 or a second cold storage device to an average temperature of, for example, at least -33 °C. The gas that has flowed through the expansion machine 26 and is not passed through the bypass 29, i.e. stream c, reaches a first cold storage device 27 or a first cold storage device, which is kept at a low average temperature, for example of max. -41 °C.

[0036] A refrigerant (or cold storage medium or coolant medium) for the first cold storage device 27 and / or the second cold storage device 30 is, for example, a mixture of water, antifreeze (e.g., ethylene glycol) or brine (e.g., potassium formate and water) and a corrosion-inhibiting medium, and the gas (hydrogen) flowing through the respective cold storage device exchanges the heat of the refrigerant in the respective cold storage device, for example, via a heat exchanger positioned therein.

[0037] In order to ensure a desired target temperature range of, for example, -33 to -40°C at a supply device 31 such as a dispenser, the two partial streams c and can be mixed or combined at point 28.

[0038] The waste heat, in particular the entire waste heat, of the compression device 140 is converted into usable cold and usable energy via the refrigeration machine, here an absorption refrigeration machine 32, and the expansion machine 26 or by using them.

[0039] The compression device 140 is, as mentioned, embodied here, for example, as a piston compressor with four stages or compression stages (the gas cylinder-piston units 2, 6, 10, 14). These gas cylinder-piston units are driven, for example, by the common drive 41. Between each two compressor stages, as well as between a final compressor stage (gas cylinder-piston unit 14) and the storage device 120, the gas (from stream a) is passed through a heat exchanger 4, 8, 12, 16.

[0040] The gas flowing there, i.e., the gas between two compressor stages and between a final compressor stage and the storage device 120, is now cooled by a coolant flow e of the absorption chiller 32, which is fed in the return line f of the absorption chiller 32, in particular to a warm inlet of the absorption chiller. For this purpose, the coolant is fed to each of the heat exchangers 4, 8, 12, 16 by means of a pump 36; the flow of the coolant can be adjusted or regulated, for example, by means of valves 37, 38, 39, 40. The heat exchangers 4, 8, 12, 16 are connected in parallel here, for example.

[0041] In addition, the compression device 140 has various housing components or components that also generate waste heat that is cooled away.

[0042] For example, these are the gas cylinder-piston units, or in particular the inlets for the gas or the cylinder jackets. On the input side, for example,

[0043] Temperatures of more than 150°C occur. Heat exchangers 45, 46, 47, 48 are provided there as an example. Another component that generates high levels of waste heat is, for example, the drive 41. Heat exchanger 49 is provided there as an example. In order to cool this component, a coolant flow g is now guided by means of a pump 42 from the first cold storage device 27 (which, as mentioned, is cooled via the expansion machine 26) to the relevant housing components or there to the heat exchangers 45, 46, 47, 48, 49. The flow of the coolant can be set or regulated, for example, by means of the valves 50, 51, 52, 53, 54. The heat exchangers 45, 46, 47, 48, 49 are connected in parallel here as an example.

[0044] It is expedient if the aforementioned housing components of the compression device 140 are also cooled by a coolant flow h from the absorption chiller 32. For this purpose, the coolant from the absorption chiller 32 can first be fed via the second cold storage device 30 by means of a pump 33 in order to cool it if necessary, and can then be mixed or admixed into the coolant flow g of the first cold storage device 27. This can be done, for example, via the bypass valve 44. This connection is advantageous, for example, for better regulation of the overall system, particularly during partial load operation. Accordingly, there is also the option of splitting the return flow from the heat exchangers 45, 46, 47, 48, 49, which can be regulated by the valve 55.

[0045] Thus, the entire waste heat from the interstage cooling as well as the cylinder jacket cooling (housing components) and the drive cooling is converted into usable cold and usable mechanical or electrical energy by the absorption chiller 32 and the expansion machine 26.

[0046] It is particularly advantageous to keep the temperature level at the inlet of the absorption chiller 32 as high as possible to achieve maximum efficiency. Therefore, the return flow f of the heated coolant from the intermediate stages leads directly to the inlet side, which has the high temperature. The cold side of the absorption chiller 32, on the other hand, cools or keeps the second cold storage device 30 cold.

[0047] In principle, even more heat exchangers can be integrated into the illustrated scheme, whereby a high temperature level is desirable but not absolutely necessary. During commissioning of the system 100, the absorption chiller 32 can be temporarily forced-heated, e.g., by electric heating cartridges or a comparable system, in order to cool the first cold storage device 27. For this purpose, if the cold storage device 27 is connected, e.g., via a heat exchanger 35 to the coolant flow e of the absorption chiller 32, a further (third) heating coil can be integrated into the heat exchanger 35, e.g., with electric heating.

[0048] The cooling of the second cold storage device 30 can be accomplished during commissioning of the system 100 by refueling into or from an external storage tank (preferably type II or III) or into one or more storage banks of the filling station.

[0049] All refueling protocols defined by, for example, SAE, JPEC, ISO or CEP (Clean Energy Partnership) or comparable ones can be served with this gas and hydraulic connection diagram or system 100, since the critical case with -33 to -40°C as the gas target temperature is already covered by the present principle and warmer refueling temperatures are also applicable.

Claims

Patent claims 1. Plant (100) for compressing, storing and providing gas, in particular hydrogen, comprising a compression device (140), a storage device (120), an expansion machine (26) and a refrigeration machine (32), in particular an absorption refrigeration machine, wherein the plant (100) is designed to compress the obtained gas (a) by means of the compression device (140), in particular in several stages, and to store the compressed gas (b) in the storage device (120), wherein the plant (100) is designed to cool the compression device (140) using the refrigeration machine (32) and the expansion machine (26).

2. System (100) according to claim 1, further comprising a first cold storage device (27), wherein the system (100) is configured to guide the stored gas from the storage device (120) via the expansion machine (26) and subsequently the first cold storage device (27).

3. System (100) according to claim 2, which is configured to cool one or more housing components of the compression device (140), in particular inlets for the gas and / or a drive (41), via a coolant flow (g) from the first cold storage device (27) to the one or more housing components of the compression device (140).

4. System (100) according to one of the preceding claims, further comprising: a second cold storage device (30), wherein the system (100) is configured to guide the stored gas from the storage device (120) directly via the second cold storage device (30).

5. System (100) according to claim 4, which is configured to cool the second cold storage device (30) via a coolant flow from the refrigeration machine (32), in particular from a cold outlet of the refrigeration machine.

6. System (100) according to claim 4 or 5, with reference at least to claim 1, which is arranged to transfer the gas by means of the first cold storage device (27) to to cool to a different, in particular lower, average temperature than by means of the second cold storage device (30), and in particular to mix gas flows after the first cold storage device (27) and the second cold storage device (30) in order to provide the gas with a desired temperature. System (100) according to one of claims 4 to 6, with reference at least to claim 1, which is designed to selectively supply the stored gas from the storage device (120) as required. - via the expansion machine (26) and subsequently the first cold storage device (27), - directly via the second cold storage device (30), or - via the expansion machine (27) and subsequently the first cold storage device (27) and also directly via the second cold storage device (30), and to make it available for use, in particular via a provision device (31) of the system. System (100) according to one of the preceding claims, with reference at least to claim 3, which is configured to further cool the one or more housing components of the compression device (140) via a coolant flow (h) from the refrigeration machine (32), in particular by admixing coolant into the coolant flow (g) of the first cold storage device (27), further in particular, with reference at least to claim 4, after cooling the second cold storage device (30).Plant (100) according to one of the preceding claims, wherein the compression device (140) has a plurality of compressor stages for multi-stage compression of the gas, and wherein the plant (100) is configured to cool gas between two compressor stages and / or between a last compressor stage and the storage device (120) via a coolant flow (e) of the refrigeration machine (32), which is supplied in the return line (f) of the refrigeration machine (32), in particular to a warm inlet of the refrigeration machine. Method for operating a plant (100) for compressing, storing, and providing gas, in particular hydrogen, in which the obtained gas (a). is compressed by means of a compression device (140), in particular in several stages, and in which the compressed gas (b) is stored in a storage device (120), wherein the compression device (140) is cooled using a refrigeration machine (32), in particular an absorption refrigeration machine (32), and an expansion machine (26).

11. The method according to claim 10, wherein stored gas from the storage device (120) is passed via the expansion machine (26) and subsequently a first cold storage device (27), and wherein the refrigeration machine (32) is temporarily forced-heated when the system (100) is put into operation in order to cool the first cold storage device (27).

12. The method according to claim 10 or 11, wherein stored gas from the storage device (120) is passed directly via a second cold storage device (30), and wherein the second cold storage device (30) is cooled when the system (100) is put into operation by refueling in an external storage tank or the storage device.

13. Method according to one of claims 10 to 12, for operating a system (100) according to one of claims 1 to 9.

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