Hydrogen filling station

Abstract

The invention relates to a hydrogen filling station which has at least one heat exchanger system. The station allows simultaneous refuelling with hydrogen at 350 bar and 700 bar.

Description

[0001] Description

[0002] Hydrogen filling station

[0003] The present invention relates to a hydrogen filling station suitable for refueling storage containers, in particular vehicle tanks, at at least two different pressure levels.

[0004] Vehicles are typically refueled with gaseous hydrogen at two pressure levels: 350 bar or 700 bar. While refueling at 350 bar is particularly common for buses and trucks, cars are preferably refueled at 700 bar. Two different technologies are used to compress the hydrogen, depending on its initial state—which is usually in liquid or gaseous form at hydrogen filling stations.

[0005] Liquid hydrogen is compressed to a pressure of 1000 bar using a cryopump. After the liquid hydrogen has been compressed in the cryopump, heat is added to the cryogenic hydrogen in a heat exchanger system using a coolant, such as freezium. The coolant cools down in the process, thus enabling the temporary storage of the cooling capacity. Immediately before refueling, this stored cooling capacity is used to cool or condition the gaseous hydrogen in the pump or dispenser to the required refueling temperature using a heat exchanger. This conditioning is necessary due to the heating of the transferred gaseous hydrogen in the vehicle tank during refueling to prevent the vehicle tank from reaching excessively high and unacceptable temperatures; the optimal refueling temperature is -40°C.

[0006] Gaseous hydrogen is compressed to a pressure of up to 1000 bar using a gas compressor, preferably a piston compressor. In contrast to the cryopump technology described above, the subsequent thermal conditioning of the compressed hydrogen for the refueling process takes place via a separate refrigeration system, resulting in additional energy requirements. The increasing number of hydrogen-powered cars and trucks is leading to a growing demand for hydrogen filling stations capable of refueling cars and trucks at the aforementioned refueling pressure levels of 350 bar and 700 bar. Furthermore, these filling stations must have comparatively high refueling rates. To achieve this, an expansion of the existing filling station systems is necessary. A mere scaling of the technologies described above is only possible at the expense of serious technical and commercial limitations.

[0007] Fueling large quantities of hydrogen requires increased cooling capacity, especially for conditioning at the dispenser. Especially for systems based on a gas compressor, the use of a powerful refrigeration system – with up to one megawatt of electrical power – is necessary. The high power consumption and the high cost of the refrigeration system increase both the operating costs (OPEX) and the capital expenditure (CAPEX) of the hydrogen filling station.

[0008] The object of the present invention is to provide a hydrogen filling station which enables the simultaneous dispensing of hydrogen at different pressure levels and with high filling rates or throughputs.

[0009] To achieve this objective, a hydrogen filling station is proposed, comprising a) a storage tank for liquefied hydrogen, b) a cryopump, by means of which hydrogen taken from the storage tank is pumped to an intermediate pressure, c) a first storage tank, which serves to store the hydrogen taken to the intermediate pressure, d) a first dispenser, which serves to dispense the hydrogen taken to the intermediate pressure and / or taken from the first storage tank, e) a compressor, by means of which the hydrogen taken to an intermediate pressure is compressed to a final pressure, f) a second storage tank, which serves to store the hydrogen taken to the final pressure, g) a second dispenser, which serves to dispense the hydrogen taken to the final pressure and / or taken from the second storage tank, and h) at least one heat exchanger system,which serves to heat the hydrogen delivered to an intermediate pressure, i) wherein the heat exchanger system is designed such that the cooling capacity stored therein can be used to cool the compressor and / or to condition the hydrogen at the first and / or second dispenser.

[0010] Due to the higher storage density, the hydrogen filling station according to the invention, which enables comparatively high throughputs, has a storage tank for liquefied hydrogen. The liquefied hydrogen is preferably stored at 1.5 barg to 8 barg. The cryopump downstream of the storage tank is preferably designed as a two-stage piston pump. With it, the liquid hydrogen withdrawn from the storage tank can be conveyed or compressed to an intermediate pressure of 300 bar to 600 bar with very low specific energy consumption and correspondingly low costs. Due to the physical restrictions of gas compression with a gas compressor, such compression is significantly less efficient and would require a large number of compression stages. The cryopump is preferably hydraulically driven.

[0011] According to the invention, the hydrogen compressed to the intermediate pressure is warmed in a heat exchanger system, preferably to ambient temperature. The coolant used in the heat exchanger system cools down in the process, thus enabling intermediate storage of the cooling capacity. According to the invention, the hydrogen compressed to the intermediate pressure and subsequently heated is temporarily stored in a first storage container and / or transferred directly to a vehicle fuel tank via a fuel pump or dispenser. In practice, the aforementioned storage container is designed as a storage bank.

[0012] According to the invention, a compressor is connected downstream of the cryopump, which compresses the hydrogen compressed to an intermediate pressure to a final pressure, preferably 700 to 1000 bar. The compressor is preferably designed as a piston compressor. The cooling capacity stored in the heat exchanger system is used according to the invention to cool this compressor. Since the hydrogen is already present at a pressure between 300 and 600 bar, the compressor can efficiently compress to the desired final pressure with few compressor stages due to the high inlet pressure. Another advantage of a compressor is that it is designed as an ambient temperature rather than a cryogenic system. The compressor therefore does not have to be cooled to a low operating temperature for operation and can therefore start up at any time. Furthermore, the wear-intensive compressor stages are directly accessible for maintenance work.Depending on the flow requirements of the hydrogen compressed to the final pressure, several compressors or

[0013] To connect compressor stages in parallel.

[0014] The hydrogen compressed to the final pressure can be stored in a second storage tank or storage bank or fed directly to a second dispenser, which serves to dispense the hydrogen pumped to the final pressure and / or withdrawn from the second storage tank.

[0015] Vehicles can now be refueled in parallel from the two storage tanks or storage banks at two different pressure levels, preferably at 350 bar and 700 bar.

[0016] As already mentioned, the hydrogen to be transferred to the vehicle tank must be conditioned before refueling. The invention utilizes the cooling capacity stored in the heat exchanger system for this purpose.

[0017] If a high flow rate were to be achieved using cryopumps alone, several cryopumps would have to be installed in parallel, which would require significant effort in terms of cryogenic equipment, such as instrumentation and control technology and valves, on the liquid hydrogen tank. Furthermore, wear on cryopumps increases significantly at pressures above 500 bar. This is of considerable importance, as the maintenance effort for a cryopump is significantly higher than for a compressor. One reason for this is the time- and labor-intensive warm-up and inerting of the entire pump system, which consists of the actual pump and a vacuum-insulated pump vessel.

[0018] In the hydrogen refueling station according to the invention, the "cryopump" and "compressor" technologies are now combined. This makes it possible to utilize the cooling capacity stored in the cryogenic, liquid hydrogen. The intermediate storage of this cooling capacity with the aid of one or more heat exchanger systems creates a thermal coupling of the various refueling station components, thus enabling demand-based cooling of the main components, in particular the compressor(s), and conditioning of the hydrogen to be refueled. Furthermore, this thermal coupling eliminates the need for a separate refrigeration system. This reduces the overall energy requirement of the refueling station and consequently allows for efficient refueling at 350 bar and 700 bar. The combination of the two technologies also ensures that the various compressor technologies operate within their efficient pressure ranges.This allows specific energy consumption and maintenance costs to be significantly minimized.

[0019] By combining both technologies with holistic thermal management, a simple way is created to meet the requirements described above, such as high throughput, low CAPEX and OPEX, for a hydrogen filling station.

[0020] Further advantageous embodiments of the hydrogen filling station according to the invention are the subject matter of the dependent patent claims.

[0021] The hydrogen filling station according to the invention and further advantageous embodiments thereof are explained in more detail below with reference to the exemplary embodiment shown in the figure. This shows a hydrogen filling station according to the invention in which, as will be explained below, two heat exchanger systems are provided. The hydrogen withdrawn from the storage container 1 for liquid hydrogen is conveyed or compressed by the cryopump 2 to an intermediate pressure of 300 bar to 600 bar. Preferably, the storage container 1, the cryopump 2 and / or the system components described below, such as the compressor, storage container, dispenser and heat exchanger system, are designed redundantly. The hydrogen compressed to the intermediate pressure has a temperature of between 35 and 70 K at the outlet of the cryopump 2.In heat exchangers 3 and 4, the hydrogen is heated to approximately ambient temperature against the coolants of two heat exchanger systems, which will be discussed in more detail below.

[0022] Subsequently, the hydrogen can be stored at the intermediate pressure in a first storage container or a first storage bank 5 or released directly via a first dispenser 6. This dispenser 6 is associated with a heat exchanger 13, which, as will be explained below, serves to condition the hydrogen to be released. Typically, the hydrogen to be released via the dispenser 6 is taken from the first storage bank 5.

[0023] Downstream of the cryopump 2 and the first storage bank 5 is a compressor 7, which serves to compress the hydrogen to a final pressure of 700 bar to 1000 bar. The compressor 7 is preferably designed as a piston compressor. The hydrogen compressed in this way is temporarily stored in a second storage container or a second storage bank 8 or dispensed directly via a second dispenser 9. This dispenser 9 is also assigned a heat exchanger 15, which, as will be explained below, serves to condition the hydrogen to be dispensed. The hydrogen to be dispensed via the dispenser 9 is usually drawn from the second storage bank 8.

[0024] In the embodiment of the hydrogen filling station according to the invention shown in the figure, two heat exchanger systems are provided. A coolant circulates in each of them. Mixtures of water and antifreeze, such as glycol (e.g., ethylene glycol, propylene glycol, and the like) or salts (e.g., potassium formate or similar), are particularly suitable for this purpose. These coolants serve to heat the hydrogen compressed by the cryopump in heat exchangers 3 and 4. The cold transferred from the hydrogen to the coolant is stored in the two heat exchanger systems. The two heat exchanger systems each have a storage tank 10 and 20, a heat exchanger 3 and 4, and several pumps 11, 12, 14, 21, 23, and 24. In addition, the first heat exchanger system, which stores cold at a lower temperature level, has two heat exchangers 13 and 15 assigned to the dispensers 6 and 9.

[0025] In the illustrated embodiment, the first heat exchanger system serves to condition the hydrogen to be dispensed via the first and second dispensers 6 and 9. For this purpose, the coolant is taken from the storage tank 10 and fed to the heat exchangers 13 and 15 by means of pumps 12 and 14. By means of pump 11, the coolant is fed 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 used coolant is taken from the storage tank 20 and fed to the compressor 7 by means of pump 21. A hydraulic drive 30 is assigned to the described cryopump 2. Both the pump of the oil circuit of this drive 30 and the heat exchanger 22 to be provided are cooled by means of the coolant of the second heat exchanger system, which is why corresponding pumps 23 and 24 are also provided.The pump 25 serves to pump the coolant through the described heat exchanger 4.

Claims

Patent claims 1. A hydrogen filling station, comprising a) a storage tank (1) for liquefied hydrogen, b) a cryopump (2), by means of which hydrogen taken from the storage tank (1) is pumped to an intermediate pressure, c) a first storage tank (5) which serves to store the hydrogen pumped to the intermediate pressure, d) a first dispenser (6) which serves to dispense the hydrogen pumped to the intermediate pressure and / or taken from the first storage tank (5), e) a compressor (7) by means of which the hydrogen pumped to an intermediate pressure is compressed to a final pressure, f) a second storage tank (8) which serves to store the hydrogen pumped to the final pressure, g) a second dispenser (9) which serves to dispense the hydrogen pumped to the final pressure and / or taken from the second storage tank (8), and h) at least one heat exchanger system (3, 4, 10 - 15, 20 - 24) which is used for heating (3,4) the hydrogen pumped to an intermediate pressure, i) 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 condition (13, 15) the hydrogen at the first and / or second dispenser (6, 9).

2. Hydrogen filling station according to claim 1, characterized in that the at least one heat exchanger system has at least one heat exchanger (3, 4) which serves for heat exchange with the hydrogen conveyed, a storage container (10, 20) which serves for storing the coolant circulating in the heat exchanger system and a compressor (11, 12, 14, 21, 23, 24).

3. Hydrogen filling station according to claim 1 or 2, characterized in that the cryopump (2) delivers to an intermediate pressure of 300 bar to 600 bar.

4. Hydrogen filling station according to one of the preceding claims, characterized in that the compressor (7) compresses to a final pressure of 700 bar to 1000 bar.

5. Hydrogen filling station according to one of the preceding claims, characterized in that the compressor (7) is a piston compressor.

6. Hydrogen filling station according to one of the preceding claims, characterized in that the storage container (1), the cryopump (2), the compressor (7), the first storage container (5), the second storage container (9), the first dispenser (6), the second dispenser (9) and / or the heat exchanger system (3, 4, 10 - 15, 20 - 24) are designed redundantly.

7. Hydrogen filling station according to one of the preceding claims, characterized in that a coolant consisting of a mixture of water and antifreeze, in particular glycol, preferably ethylene glycol and / or propylene glycol, or salts, in particular potassium formate, circulates in the at least one heat exchanger system.

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