Valve assembly for a water separator, and water separator

Abstract

The invention relates to a valve assembly (1) for a water separator (2), comprising: - a valve block (3) for connecting the valve assembly (1) to the water separator (2), - at least one discharge valve (4) for discharging fluid from the water separator, and - a gas sensor (5) for detecting gas in the fluid discharged from the water separator (2) via the at least one discharge valve (4), wherein the at least one discharge valve (4) opens into a fluid channel (6) that is formed in the valve block (3) and is fluidically connected to a receiving area (7) which is formed in the valve block (3) and into which the gas sensor (5) is inserted, and in the final installation position of the valve assembly (1), the receiving area (7) is geodesically higher than the fluid channel (6). The invention also relates to a water separator (2) comprising a valve assembly (1) according to the invention.

Description

[0001] Description

[0002] title

[0003] Valve assembly for a water separator, water separator

[0004] The invention relates to a valve assembly for a water separator. Water can be drained from the water separator via the valve assembly. Furthermore, the invention relates to a water separator with a valve assembly according to the invention.

[0005] A preferred application of the invention is fuel cell systems in which a water separator is used to separate product water from a gas stream. The gas stream can, in particular, be an anode gas stream containing hydrogen.

[0006] State of the art

[0007] Hydrogen-based fuel cells convert hydrogen and oxygen into electrical energy, heat, and water. The hydrogen is fed to an anode, and the oxygen—in the form of ambient air—is fed to a cathode of the fuel cell. The anode is supplied with hydrogen via an anode circuit of an anode subsystem, through which fresh hydrogen from a tank and a recirculated gas containing residual hydrogen, nitrogen, and water are fed to the fuel cells. Over time, the anode gas recirculated via the anode circuit becomes enriched with nitrogen, which diffuses from the cathode side to the anode side. Furthermore, the anode gas carries water, which is produced as a byproduct of the electrochemical reaction in the fuel cells and is therefore also called product water.

[0008] To prevent a hydrogen deficiency in the fuel cells, the anode circuit must be purged from time to time. To do this, a drain valve, known as a purge valve, is opened and the gas released through this valve is replaced with fresh hydrogen from the tank. The water contained in the anode gas is separated from the gas stream using a water separator. This first collects the water in a container. When the container is full, it must be emptied. For this purpose, another drain valve, known as the drain valve, is provided on the container. Since anode gas escapes through the open drain valve once the container is completely empty, not only water but also hydrogen can be discharged through the drain valve. To detect this, a gas sensor, in particular a hydrogen sensor, is usually provided downstream of the drain valve in an outlet line through which the fluid released from the container is discharged.If hydrogen is detected by the gas sensor, this is the latest time to close the drain valve. Accumulation of excessive amounts of hydrogen in the outlet line can lead to an explosive gas mixture.

[0009] If water backs up in the outlet line, it can enter the gas sensor and impair its functionality. At low outside temperatures, the water can also freeze and cause irreparable damage to the gas sensor. If this occurs, the hydrogen discharge through the drain valve will no longer be detected. This can not only pose a safety risk but also lead to significant hydrogen loss.

[0010] The present invention is concerned with the object of preventing or at least reducing the above-mentioned disadvantages of the prior art.

[0011] To achieve this objective, the valve assembly having the features of claim 1 is proposed. Advantageous further developments of the invention are set forth in the subclaims. Furthermore, a water separator having a valve assembly according to the invention is specified.

[0012] Disclosure of the invention

[0013] The proposed valve assembly for a water separator comprises: a valve block for connecting the valve assembly to the water separator, at least one drain valve for draining fluid from the water separator, and a gas sensor for detecting gas in the fluid drained from the water separator via the at least one drain valve. The at least one drain valve opens into a fluid channel formed in the valve block, which is fluidically connected to a receptacle formed in the valve block into which the gas sensor is inserted. In the final installation position of the valve assembly, the receptacle is arranged geodetically higher than the fluid channel.

[0014] The geodetically higher position of the gas sensor relative to the fluid channel leads to the formation of a gas-filled volume between the gas sensor and the fluid channel. This prevents water from entering the gas sensor in the event of a backflow in the fluid channel. The backflow of water traps the gas in the volume, forming a gas cushion that protects the gas sensor from water ingress. The gas-filled volume does not prevent hydrogen, which is released with water into the fluid channel via the release valve, from reaching the gas sensor and being detected by it.

[0015] A further advantage of the valve assembly according to the invention arises from the integration of the at least one drain valve and the gas sensor into a common valve block. This results in a spatially close arrangement of the drain valve and gas sensor. Hydrogen discharged via the at least one drain valve is directly detected by the gas sensor, so that the drain valve can be closed in the shortest possible time. This enables fast response times and thus low hydrogen losses. In addition, the measuring accuracy of the gas sensor is increased because there are no further interfaces or connections of fluid lines between the drain valve and the gas sensor, thus preventing dilution of the fluid in the fluid channel. The increased measuring accuracy, in turn, makes it possible to dispense with a level sensor accommodated in the water separator, thus saving components and thus costs.

[0016] According to a preferred embodiment of the invention, the fluid channel is indirectly fluidically connected to the receptacle via at least one branching riser. The at least one riser allows a greater distance between the gas sensor and the fluid channel. Furthermore, the at least one riser forms a defined volume filled with gas. According to a preferred embodiment of the invention, the fluid channel formed in the valve block has a gradient so that, when the drain valve is open, water drained from the water separator flows through the fluid channel under gravity. If the drained water carries hydrogen and / or another gas with it, this gas separates from the liquid flow in the area of ​​the gas sensor and rises to the gas sensor. The detection of hydrogen is thus ensured.

[0017] In a further development of the invention, it is proposed that a heating device for heating the valve assembly be integrated into the valve block. With the help of the heating device, water can be prevented from freezing and / or already frozen water can be thawed if there is a risk of frost. In this way, damage caused by ice pressure, in particular to the at least one drain valve of the valve assembly, can be avoided.

[0018] The gas sensor is already protected from water ingress and thus from ice pressure damage due to its geodetically higher position relative to the fluid channel. However, at low outside temperatures, the gas sensor can become a heat sink, allowing water vapor that may be present in the gas-filled volume between the fluid channel and the gas sensor to condense, precipitate on the gas sensor, and freeze. To prevent this, the heating device is preferably arranged so that it heats the at least one drain valve and the gas sensor. Since these are located close to one another, this is easily possible. Therefore, only one heating device is required to heat the at least one drain valve and the gas sensor.

[0019] The heating device integrated into the valve block is preferably an electric heating device. This requires little space, making it easy to integrate, and ensures rapid heating.

[0020] The valve block preferably has a connecting section for connection to the water separator. The connecting section facilitates the establishment of the connection between the valve assembly and the water separator. The connecting section is preferably designed as a connecting piece. The connecting piece can establish not only a mechanical connection but also a fluidic connection between the at least one drain valve integrated into the valve assembly and the water separator, in particular, a storage volume of the water separator in which the separated water is collected.

[0021] Furthermore, the valve block preferably has a connecting section for connection to an outlet line. The fluid drained from the water separator via the at least one drain valve can then be discharged via the outlet line. The connecting section is therefore also preferably designed as a connecting piece.

[0022] An additional drain valve can also be integrated into the proposed valve assembly. A first drain valve can then be used as a drain valve, and a second drain valve can be used as a purge valve. Furthermore, the drain and purge functions can be implemented in a single drain valve. In this case, the number of drain valves integrated into the valve assembly can be limited to one. This helps save components, thus saving installation space and costs.

[0023] Furthermore, a water separator with a valve assembly according to the invention is proposed. The water separator, in particular a storage volume of the water separator, can be emptied via the at least one drain valve. If anode gas and thus hydrogen escapes from the storage volume after the water has been drained, this is immediately detected by the gas sensor of the valve assembly and the drain valve can be quickly closed. In this way, hydrogen losses when draining the water separator can be kept to a minimum. The geodetically higher position of the gas sensor relative to the fluid channel prevents water from entering the gas sensor, even if a backflow occurs in the fluid channel. This ensures that the gas sensor remains fully functional even during a frost event.

[0024] The valve assembly according to the invention is preferably arranged in a base region of the water separator. In this way, water can be drained from the water separator solely by gravity when the at least one drain valve is opened.

[0025] The proposed water separator can be integrated, in particular, into an anode circuit of an anode subsystem, through which a fuel cell stack can be supplied with fresh hydrogen as well as hydrogen-containing recirculate. The water separator can be used to remove product water from the recirculate.

[0026] Preferred embodiments of the invention are described in more detail below with reference to the accompanying drawings. These show:

[0027] Fig. 1 is a schematic sectional view of a water separator with a valve assembly according to the invention,

[0028] Fig. 2 shows an enlarged section of Figure 1 in the area of ​​the valve assembly and

[0029] Fig. 3 is a sectional view of another valve assembly according to the invention.

[0030] Detailed description of the drawings

[0031] Figure 1 shows a water separator 2 with a valve assembly 1 according to the invention. The valve assembly 1 is arranged below the water separator 2. The preferred application of the water separator 2 is in anode subsystems for supplying a fuel cell stack (not shown) with hydrogen.

[0032] The water separator 2 shown in Figure 1 has a storage volume 20 for collecting separated water, wherein the water is separated by a gas stream that is admitted into the water separator 2 via an inlet 15 and discharged from the water separator 2 via an outlet 16. The separated water collects in the lower region of the storage volume 20 and forms a liquid phase 17 there. Above this is a gas phase 18. A fill level sensor 14 is accommodated in the storage volume 20, which measures the fill level in the storage volume 20. The fill level sensor 14 is merely optional and can also be omitted.

[0033] The storage volume 20 has a maximum capacity, so that water must be drained from the storage volume 20 from time to time. This is done via the valve assembly 1 located below the water separator 2. The valve assembly 1 is shown again in an enlarged form in Figure 2, so that the description is based on Figure 2.

[0034] The valve assembly 1 has a valve block 3 into which a drain valve 4 and a gas sensor 5 are integrated. The gas sensor 5 is inserted into a receptacle 7 formed in the valve block 3. The drain valve 4 integrated into the valve block 3 opens into a fluid channel 6 having a gradient 13, so that water drained from the storage volume 20 via the drain valve 4 flows, driven by gravity, via the fluid channel 6 to an outlet line 11 connected to the fluid channel 6. The fluidic connection is established via connecting sections 9, 10 of the valve block 3. The connecting section 9, via which the drain valve 4 is connected to the storage volume 20, is surrounded by a sealing ring 12 to seal the storage volume 20 from the outside.

[0035] When the drain valve 4 is open, water flows from the storage volume 20 into the fluid channel 6 and via the fluid channel 6 into the outlet line 11. When there is no more water in the storage volume 20, gas flows out via the drain valve 4. Since this gas may contain hydrogen when the water separator 2 is used in an anode subsystem, the drain valve should be closed in a timely manner to avoid excessive hydrogen losses.

[0036] The escape of hydrogen via the drain valve 4 is detected by the gas sensor 5. This is therefore preferably designed as a hydrogen sensor. The gas sensor 5, or the receptacle 7 accommodating the gas sensor 5, is arranged geodetically higher than the fluid channel 6 in the valve block 3, so that a gas-filled volume remains between the gas sensor 5 and the fluid channel 6. In this case, this is defined by two risers 19 that fluidically connect the receptacle 7 to the fluid channel 6. The gas-filled volume prevents water from penetrating the gas sensor 5, so that it is excellently protected, particularly against damage caused by freezing water.

[0037] Figure 3 shows a further preferred embodiment of a valve assembly 1 according to the invention. The section is positioned such that the gas sensor 5 is located behind the drain valve 4 and is therefore not visible in Figure 3. Instead, Figure 3 shows a connecting section 9 for connecting the valve assembly 1 to a water separator 2 and a connecting section 10 for connecting the valve assembly 1 to an outlet line 11. Both connecting sections 9, 12 are designed as connecting pieces. Furthermore, an electrical heating device 8 is integrated into the valve block 3 of the valve assembly 1, by means of which the valve assembly can be heated as needed. Due to the spatial proximity of the drain valve 4 and the gas sensor 5, only one heating device 8 is required.

Claims

Claims 1. Valve assembly (1) for a water separator (2), comprising a valve block (3) for connecting the valve assembly (1) to the water separator (2), at least one drain valve (4) for draining fluid from the water separator and a gas sensor (5) for detecting gas in the fluid that is drained from the water separator (2) via the at least one drain valve (4), wherein the at least one drain valve (4) opens into a fluid channel (6) formed in the valve block (3), which is fluidically connected to a receptacle (7) formed in the valve block (3) into which the gas sensor (5) is inserted, and wherein, in the final installation position of the valve assembly (1), the receptacle (7) is arranged geodetically higher than the fluid channel (6).

2. Valve assembly (1) according to claim 1, characterized in that the fluid channel (6) is fluidically connected indirectly to the receptacle (7) via at least one branching riser line (19).

3. Valve assembly (1) according to claim 1 or 2, characterized in that the fluid channel (6) has a gradient (13) so that when the drain valve (4) is open, water drained from the water separator (2) flows through the fluid channel (6) under the force of gravity.

4. Valve assembly (1) according to one of the preceding claims, characterized in that a heating device (8), preferably an electrical heating device (8), for heating the valve assembly (1) is integrated into the valve block (3).

5. Valve assembly (1) according to one of the preceding claims, characterized in that the valve block (3) has a connecting section (9) for connection to the water separator (2), wherein the connecting section (9) is preferably designed as a connecting piece.

6. Valve assembly (1) according to one of the preceding claims, characterized in that the valve block (3) has a connecting section (10) for connection to an outlet line (11), wherein the connecting section (10) is preferably designed as a connecting piece.

7. Water separator (2) with a valve assembly (1) according to one of the preceding claims, wherein the valve assembly (1) is preferably arranged in a base region of the water separator (2).

Images