Hydrogen refueling station

Abstract

The present invention relates to a hydrogen refueling station having at least one heat exchanger system. The station is capable of simultaneously refueling with hydrogen at 350 bar and 700 bar.

Description

Technical Field

[0001] The present invention relates to a hydrogen filling station suitable for refilling storage tanks, particularly vehicle tanks, at at least two different pressure levels.

Background Art

[0002] Vehicles are typically refilled with gaseous hydrogen at two pressure levels, namely 350 bar or 700 bar. Refilling at 350 bar is mainly used for buses and trucks, while passenger cars are preferably refilled at 700 bar. To compress hydrogen, two different technologies are used depending on the initial state of hydrogen, and hydrogen is usually available in liquid or gaseous form at a hydrogen filling station.

[0003] Liquid hydrogen is compressed to a pressure of 1,000 bar using a so-called cryopump. When liquid hydrogen is compressed in the cryopump, heat is supplied to the cryogenic hydrogen in the heat exchanger system using a coolant, for example, freon. The coolant is cooled and enables intermediate storage of cooling capacity in its function as a cold storage medium. Immediately before the refilling process, the stored cooling capacity is used to cool or adjust the gaseous hydrogen in the filling pump or dispenser to the required refilling temperature using a heat exchanger. This adjustment is necessary to prevent the temperature of the vehicle tank from becoming too high due to the heating of the gaseous hydrogen transferred into the vehicle tank during refilling and exceeding the following allowable limits. The optimal refilling temperature is -40°C.

[0004] Gaseous hydrogen is compressed to a maximum pressure of 1,000 bar using a gas compressor, preferably a piston compressor. In contrast to the above-mentioned cryopump technology, the subsequent heat adjustment of the compressed hydrogen for the refilling process is performed via a separate cooling system, resulting in additional energy requirements.

[0005] As the number of hydrogen passenger cars and trucks increases, so does the demand for hydrogen refueling stations where these vehicles can be refueled at the aforementioned refueling pressure levels of 350 bar and 700 bar. These refueling stations also need to have relatively high refueling rates. To achieve this, the expansion of existing refueling station systems is necessary. Simply scaling up the technologies described above is only possible if significant technical and commercial limitations are acceptable.

[0006] The refueling of large quantities of hydrogen necessitates increased demand for cooling capacity, particularly during adjustments at the dispenser. The use of a powerful cooling system with an electrical connection load of up to 1 megawatt is required, especially for systems based on gas compressors. The high power consumption and high cost of the cooling system increase both the operating expenses (OPEX) and capital expenditures (CAPEX) of the hydrogen refueling station. [Overview of the project]

[0007] The object of the present invention is to provide a hydrogen refueling station that enables the simultaneous distribution of hydrogen at different pressure levels and at high refueling rates or processing volumes.

[0008] To achieve this objective, a hydrogen refueling station has been proposed, and the hydrogen refueling station is a) Storage tanks for liquefied hydrogen, b) A cryopump that pumps hydrogen taken from the storage tank to an intermediate pressure, c) A first storage tank used for storing hydrogen that has been pumped to an intermediate pressure, d) A first dispenser used to distribute hydrogen pumped to an intermediate pressure and / or hydrogen taken from a first storage tank, e) A compressor that compresses the hydrogen, which has been pumped to an intermediate pressure, to the final pressure, f) A second storage tank used to store hydrogen that has been pumped to its final pressure, g) A second dispenser used to distribute hydrogen pumped to the final pressure and / or hydrogen taken from a second storage tank, h) comprising at least one heat exchanger system used to heat pumped hydrogen to an intermediate pressure, i) The heat exchanger system is designed such that the cooling capacity stored therein can be used to cool the compressor and / or to prepare hydrogen in the first and / or second dispensers.

[0009] The hydrogen refueling station according to the present invention, which enables a relatively high processing capacity due to a higher storage density, has a storage tank for liquefied hydrogen. The liquefied hydrogen is preferably stored at 1.5 barg to 8 barg. A cryopump downstream of the storage tank is preferably designed as a two-stage piston pump. This pump can be used to pump or compress the liquid hydrogen taken from the storage tank to an intermediate pressure of 300 bar to 600 bar with a very low specific energy consumption rate and a correspondingly low cost. Such compression is significantly less efficient due to the physical limitations of gas compression by gas compressors and requires a large number of compression stages. The cryopump is preferably hydraulically driven.

[0010] According to the present invention, hydrogen compressed to an intermediate pressure is preferably heated to ambient temperature in a heat exchanger system. This cools the coolant used in the heat exchanger system, enabling intermediate storage of its cooling capacity.

[0011] According to the present invention, hydrogen, compressed to an intermediate pressure and then heated, is temporarily stored in a first storage tank and / or transferred directly to a vehicle tank via a filling pump or dispenser. In practice, the aforementioned storage tank is designed as a storage bank.

[0012] According to the present invention, a compressor is connected downstream of the cryopump to compress the hydrogen, which has been compressed to an intermediate pressure, to a final pressure, preferably 700 to 1,000 bar. The compressor is preferably designed as a piston compressor. According to the present invention, the cooling capacity stored in the heat exchanger system is used to cool the compressor. Since the hydrogen is already present at a pressure of 300 to 600 bar, the compressor can efficiently compress the hydrogen to the desired final pressure in just a few compressor stages due to the high inlet pressure. Another advantage of the compressor is that it is designed as an ambient temperature system rather than a cryogenic system. Therefore, the compressor does not need to be cooled to a low operating temperature for operation and can therefore be started at any time. Furthermore, the compressor stages that are subject to heavy wear are directly accessible for maintenance work. Depending on the flow rate requirements of the hydrogen to be compressed to the final pressure, it may be necessary to connect several compressors or compressor stages in parallel.

[0013] The hydrogen, compressed to its final pressure, may be stored in a second storage tank or storage bank, or supplied directly to a second dispenser, which functions to distribute the hydrogen pumped to its final pressure and / or the hydrogen taken from the second storage tank.

[0014] Here, the vehicle may be supplied in parallel from two storage tanks or storage banks at two different pressure levels, preferably 350 bar and 700 bar.

[0015] As already mentioned, the hydrogen transferred to the vehicle tank must be adjusted before refueling. According to the present invention, the cooling capacity stored in the heat exchanger system is used for this purpose.

[0016] If high flow rates are to be handled using only cryopumps, several cryopumps must be installed in parallel, requiring considerable effort regarding cryogenic equipment on the liquid hydrogen tank, such as measurement, control, and regulation technologies, as well as valves. Furthermore, cryopump wear increases significantly at pressures exceeding 500 bar. The maintenance effort required for cryopumps is considerably higher than that for compressors, making it quite relevant. One reason for this is the time-consuming and labor-intensive preheating and deactivation of the entire pump system, which consists of the actual pump and the vacuum-insulated pump tank.

[0017] In the hydrogen refueling station according to the present invention, "cryo-pump" technology and "compressor" technology are combined. This allows the cooling capacity stored in cryogenic liquid hydrogen to be utilized. Intermediate storage of this cooling capacity using one or more heat exchanger systems results in thermal coupling of various refueling station components, thus enabling the adjustment of cooling and replenishment hydrogen based on the demands of the main components, particularly the compressor. Furthermore, this thermal coupling can eliminate the need for a separate cooling system. This reduces the overall energy demand of the refueling station, resulting in efficient refueling at 350 bar and 700 bar. The combination of the two technologies also ensures that different compressor technologies operate within their efficient pressure ranges. This can significantly minimize specific energy consumption and maintenance costs.

[0018] Combining both technologies with overall thermal management provides a simple method for hydrogen refueling stations that meets the above requirements, such as high capacity and low CAPEX and OPEX.

[0019] Further advantageous embodiments of the hydrogen refueling station according to the present invention are the subject of the dependent claims. [Brief explanation of the drawing]

[0020] [Figure 1] This figure shows an exemplary embodiment of a hydrogen refueling station according to the present invention.

Best Mode for Carrying Out the Invention

[0021] The hydrogen filling station according to the present invention and further advantageous embodiments thereof will be described in more detail below with reference to the exemplary embodiments shown in the figures. The exemplary embodiments show a hydrogen filling station according to the present invention provided with two heat exchanger systems, as will be described below.

[0022] Hydrogen taken out from the storage tank 1 for liquid hydrogen is pumped or compressed by the cryopump 2 to an intermediate pressure of 300 bar to 600 bar. Preferably, the storage tank 1, the cryopump 2, and / or system components described below, such as compressors, storage tanks, dispensers, and heat exchanger systems, are designed redundantly. The hydrogen compressed to the intermediate pressure has a temperature of 35 to 70 K at the outlet of the cryopump 2. In the heat exchanger 3 and the heat exchanger 4, the hydrogen is heated to approximately ambient temperature with respect to the coolant of the two heat exchanger systems discussed in more detail below. Thereafter, the hydrogen can be stored at the intermediate pressure in the first storage tank or the first storage bank 5, or directly distributed via the first dispenser 6. The dispenser 6 is associated with a heat exchanger 13 that functions to condition the hydrogen to be distributed, as will be described below. Typically, the hydrogen distributed via the dispenser 6 is taken out from the first storage bank 5.

[0023] The compressor 7 is located downstream of the cryopump 2 and the first storage bank 5 and functions to compress the hydrogen to a final pressure of 700 bar to 1,000 bar. The compressor 7 is preferably designed as a piston compressor. The hydrogen compressed in this way is temporarily stored in the second storage tank or the second storage bank 8, or directly distributed via the second dispenser 9. The dispenser 9 is also associated with a heat exchanger 15 that functions to condition the hydrogen to be distributed, as will be described below. Typically, the hydrogen distributed via the dispenser 9 is taken out from the second storage bank 8.

[0024] In an exemplary embodiment of the hydrogen refueling station according to the present invention shown in the figure, two heat exchanger systems are provided. In each, a coolant is circulated. In particular, a mixture of water and an antifreeze such as glycol (e.g., ethylene glycol, propylene glycol, etc.) or salt (e.g., potassium formate, etc.) is suitable for this purpose. These coolants are used in heat exchangers 3 and 4 to heat hydrogen compressed by a cryopump. The cold released from the hydrogen into the coolant is stored in the two heat exchanger systems. The two heat exchanger systems each have storage tanks 10 and 20, heat exchangers 3 and 4, and several pumps, pumps 11, 12, 14, 21, 23, and 24. Furthermore, a first heat exchanger system for storing cold at low temperatures has two heat exchangers 13 and 15 assigned to dispensers 6 and 9.

[0025] In the illustrated exemplary embodiment, the first heat exchanger system serves to regulate the hydrogen distributed through the first dispenser 6 and the second dispenser 9. For this purpose, the coolant is drawn from the storage tank 10 and supplied to the heat exchangers 13 and 15 by pumps 12 and 14. The coolant is supplied by pump 11 to the heat exchanger 3, which serves to heat the hydrogen. The second heat exchanger system, which stores cold at a higher temperature level, serves to cool the compressor 7. For this purpose, the coolant used is drawn from the storage tank 20 and supplied to the compressor 7 by pump 21. The described cryopump 2 is associated with a hydraulic drive unit 30. Both the pump in the oil circuit of this drive unit 30 and the supplied heat exchanger 22 are cooled by the coolant of the second heat exchanger system, which is why corresponding pumps 23 and 24 are also provided. Pump 25 serves to pump the coolant through the described heat exchanger 4.

Claims

1. A hydrogen refueling station, wherein the hydrogen refueling station is a) Storage tank (1) for liquefied hydrogen, b) A cryopump (2) for pumping hydrogen extracted from the storage tank (1) to an intermediate pressure, c) A first storage tank (5) used for storing the hydrogen that has been pumped up to the intermediate pressure, d) A first dispenser (6) used to distribute the hydrogen pumped up to the intermediate pressure and / or the hydrogen taken from the first storage tank (5), e) A compressor (7) that compresses the hydrogen, which has been pumped to an intermediate pressure, to a final pressure, f) A second storage tank (8) used for storing the hydrogen that has been pumped up to the final pressure, g) A second dispenser (9) used to distribute the hydrogen pumped up to the final pressure and / or the hydrogen taken from the second storage tank (8), h) comprising at least one heat exchanger system (3, 4, 10-15, 20-24) used to heat the pumped hydrogen to an intermediate pressure (3, 4), i) A hydrogen refueling station, wherein the heat exchanger system is designed such that the cooling capacity stored therein can be used to cool the compressor (7) and / or to adjust the hydrogen in the first dispenser (6) and / or the second dispenser (9) (13, 15).

2. The hydrogen refueling station according to claim 1, characterized in that the at least one heat exchanger system comprises at least one heat exchanger (3, 4) that performs the function of exchanging heat with the pumped hydrogen, storage tanks (10, 20) that perform the function of storing a coolant circulating within the heat exchanger system, and compressors (11, 12, 14, 21, 23, 24).

3. The hydrogen refueling station according to claim 1 or 2, characterized in that the cryopump (2) pumps up to an intermediate pressure of 300 bar to 600 bar.

4. The hydrogen refueling station according to any one of claims 1 to 3, characterized in that the compressor (7) compresses to a final pressure of 700 bar to 1,000 bar.

5. The hydrogen refueling station according to any one of claims 1 to 4, characterized in that the compressor (7) is a piston compressor.

6. A hydrogen refueling station according to any one of claims 1 to 5, characterized in that the storage tank (1), the cryopump (2), the compressor (7), the first storage tank (5), the second storage tank (9), the first dispenser (6), the second dispenser (9), and / or the heat exchanger system (3, 4, 10-15, 20-24) are designed to be redundant.

7. A hydrogen refueling station according to any one of claims 1 to 6, characterized in that a coolant comprising a mixture of water and an antifreeze, particularly glycol, preferably ethylene glycol and / or propylene glycol, or a salt, particularly potassium formate, circulates within the at least one heat exchanger system.

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