FUEL CELL SUBMARINE TANK SYSTEM

Description

[0001] The invention relates to a submarine, wherein the submarine generates energy using a fuel cell, with the hydrogen required for the fuel cell being obtained from methanol in a reformer. For storing the methanol and water, the submarine has at least three tanks in which methanol and water are stored alternately.

[0002] The use of fuel cells is known in the field of non-nuclear submarines, for example the Class 212 A. The hydrogen required for the operation of the fuel cell is stored in metal hydride storage tanks.

[0003] Metal hydride storage systems have proven to be very suitable for boats with a displacement of approximately 2,000 tons. However, for boats with significantly higher displacements, it may be more efficient to integrate a reformer into the boat in addition to or instead of the metal hydride storage systems and to carry methanol in a compact storage container.

[0004] During operation, methanol and oxygen are consumed, and water and carbon dioxide are produced. If the produced water and carbon dioxide are removed from the boat, the weight decreases, thereby changing the boat's buoyancy. Ballast water would have to be taken on to compensate for this.

[0005] A method for operating a fuel cell system is known from US 6 063 515 A.

[0006] The object of the invention is to create a submarine which uses methanol as fuel and has the smallest possible change in buoyancy when consuming the methanol.

[0007] This object is achieved by the submarine having the features specified in claim 1, as well as by the method having the features specified in claim 12. Advantageous further developments emerge from the subclaims, the following description and the drawing.

[0008] The submarine according to the invention has at least one first fuel cell and at least one first reformer. The at least one first reformer is designed to produce hydrogen from methanol. The submarine has at least a first tank, a second tank, and a third tank. The first tank is connectable to the reformer for fluid transport, the second tank is connectable to the reformer for fluid transport, and the third tank is connectable to the reformer for fluid transport. Furthermore, the first tank is connectable to the second tank for fluid transport, the first tank is connectable to the third tank for fluid transport, and the second tank is connectable to the third tank for fluid transport.

[0009] To produce hydrogen from methanol, the reformer must be supplied with both methanol and water. To do this efficiently, the submarine has at least three tanks, preferably more than three. These tanks can store either methanol or water. Since there are no defined methanol storage tanks or water storage tanks, each tank must be connected to the reformer. Additionally, it is necessary to be able to pump fluids from one tank to another, so that each tank can be connected to any other tank.

[0010] For the purposes of the invention, water refers in particular to process water required or generated in connection with the operation of the reformer or fuel cell. Drinking water carried on board is to be distinguished from this. Water within the meaning of the invention generally contains impurities, particularly methanol; it is not chemically pure water.

[0011] Typically, before a ship departs, one tank will contain water, while all other tanks will be filled with methanol. Preferably, the tank containing water is only partially filled so that it can absorb the reaction water and condensate produced by the reformer and / or fuel cell. During the voyage, methanol is removed, and as soon as a tank containing methanol is empty, the reaction water and condensate produced by the reformer and / or fuel cell are introduced into it.

[0012] This allows both fluids, methanol and water, to be stored in a very compact manner. At the same time, the submarine's buoyancy can be kept nearly constant during operation.

[0013] According to the invention, the first tank is connected to a first outlet valve at the bottom and to a first inlet valve at the top. The second tank is connected to a second outlet valve at the bottom and to a second inlet valve at the top. The third tank is connected to a third outlet valve at the bottom and to a third inlet valve at the top.

[0014] Preferably, each tank is provided with a single inlet valve on top for the transport of methanol and / or water.

[0015] According to the invention, the first outlet valve, the second outlet valve and the third outlet valve are connected via an outlet connection.

[0016] According to the invention, the first inlet valve, the second inlet valve and the third inlet valve are connected via an inlet connection.

[0017] According to the invention, the inlet and outlet connections are connected via a pump. This makes it particularly easy to transport liquid from each tank to every other tank using only a single active pump element.

[0018] In a further embodiment of the invention, the inlet connection is connected to a refueling coupling. Methanol or water can be pumped into the inlet connection via the refueling coupling and into a selected tank via the inlet connection.

[0019] According to the invention, the first tank is connected to a first methanol discharge valve at its bottom. The second tank is connected to a second methanol discharge valve at its bottom, and the third tank is connected to a third methanol discharge valve at its bottom.

[0020] According to the invention, the first methanol discharge valve, the second methanol discharge valve and the third methanol discharge valve are connected via a methanol discharge connection.

[0021] According to the invention, the methanol discharge connection is connected to the at least one first reformer via at least one first methanol discharge pump.

[0022] This design allows methanol to be transported from any tank to the first reformer.

[0023] According to the invention, the first tank is connected to a first water drain valve at its bottom. The second tank is connected to a second water drain valve at its bottom. The third tank is connected to a third water drain valve at its bottom.

[0024] According to the invention, the first water drain valve, the second water drain valve and the third water drain valve are connected via a water drain connection.

[0025] According to the invention, the water drain connection is connected to the at least one first reformer via at least one first water drain pump.

[0026] This design allows water to be pumped from each tank into the first reformer.

[0027] In a particularly preferred embodiment, the outlet valve, the methanol drain valve and the water drain valve of a tank are each connected to the tank via a common connection, so that there is only one opening at the bottom for connection to the three valves.

[0028] In a further embodiment of the invention, the first tank, the second tank, and the third tank are sealed from the atmosphere of the submarine, wherein the submarine has a device for introducing inert gas into at least the first tank, the second tank, and the third tank. Since methanol is toxic, methanol should not be released into the atmosphere in gaseous form. This can be achieved, in particular, by a protective gas atmosphere. At the same time, this also ensures explosion protection.

[0029] In a further embodiment of the invention, the inert gas is nitrogen, carbon dioxide, helium, neon, argon, or a mixture thereof. Nitrogen, carbon dioxide, or argon is particularly preferred, since these gases can be used for various purposes on board a submarine.

[0030] In a further embodiment of the invention, at least two tanks are arranged adjacent to each other. The two adjacent tanks are connected at the top by an overflow pipe, with the connections between the overflow pipe and the tanks being located on the side opposite the adjacent tank. This arrangement ensures that no liquid flows from one tank into a neighboring tank, even when the submarine is at an extreme incline.

[0031] In a further embodiment of the invention, the submarine has at least one degassing tank. After degassing, the water can be conveyed from the degassing tank via the inlet connection into a selected tank.

[0032] In a further embodiment of the invention, the submarine has a cathode-side water separator, wherein the cathode-side water separator is connected to the cathode side of the at least one fuel cell, wherein the cathode-side water separator is connected to the outgassing tank. Reaction water from the cathode side of the fuel cell is first conveyed to the outgassing tank. The reaction water from the cathode side of the fuel cell is enriched with oxygen. This oxygen can be released into the atmosphere in the outgassing tank.

[0033] Reaction water from the anode side of the fuel cell is produced in significantly smaller quantities, as the product is produced on the cathode side. However, since this water may contain hydrogen, it is preferably stored in a separate tank or used to humidify the hydrogen stream in the feed to the anode side of the fuel cell.

[0034] In a further embodiment of the invention, the outgassing tank is connected to the reformer for transferring condensate from the reformer to the outgassing tank.

[0035] In a further embodiment of the invention, the outgassing tank is connected to the submarine's atmosphere. Since this primarily releases oxygen, which is consumed by the crew, no further storage or disposal requirements arise.

[0036] In a further embodiment of the invention, the submarine has an even number of tanks, with half of the tanks arranged on the starboard side and the other half on the port side. In an advantageous development of this embodiment, the submarine has a total of eight tanks, with four tanks arranged on the starboard side and four tanks on the port side. Particularly preferably, one of the tanks is a degassing tank. When leaving the harbor, six tanks can thus be filled with methanol and one tank with some water. This results in the most efficient use of space on board.

[0037] In a further embodiment, the submarine has a pressure hull, and the tanks are arranged outside the pressure hull. These are preferably arranged between the pressure hull of the submarine and another fairing. Particularly preferably, they are arranged around another tank, in particular the oxygen tank.

[0038] In a further embodiment of the invention, each tank has only one inlet for liquids on the top and one outlet for liquids on the bottom. Additionally, each tank preferably has at least one inlet for protective gas. Further preferably, each tank has at least one overflow pipe. Additionally, each tank can have a fill level sensor and, if appropriate, pressure and / or temperature sensors.

[0039] In a further embodiment of the invention, the pressure body forms at least part of the tank.

[0040] In a further embodiment of the invention, at least one tank has a bladder, wherein the bladder is designed to hold liquid. A bladder is understood to be a flexible device for holding liquid, which is usually made of a plastic. The bladder increases its volume when liquid is added and decreases its volume when liquid is removed. The bladder can prevent contact between the liquid and the tank wall. One advantage of using a bladder can be the elimination of a protective gas atmosphere, since methanol vapors cannot escape from the bladder to the outside.

[0041] In a further aspect, the invention relates to a method for operating a submarine according to the invention. The at least one first tank is filled with methanol, the at least one second tank is filled with water. Methanol is conveyed from the first tank into at least one first reformer. Water is conveyed from the second tank into the at least one first reformer. Reaction water is conveyed from the fuel cell into the second tank. Condensate is conveyed from the reformer into the second tank. In this case, the reaction water from the fuel cell or the condensate from the reformer does not have to be conveyed directly into the second tank, but can first be conveyed into a degassing tank and from the degassing tank into the second tank.

[0042] In a further embodiment of the invention, methanol is withdrawn from the first tank until the fill level is below 5% of the tank volume, preferably below 3% of the tank volume, particularly preferably below 2% of the tank volume, wherein the fill level is above 1% of the tank volume.

[0043] A minimum fill level prevents the pumps from running dry.

[0044] In a further embodiment of the invention, reaction water from the fuel cell and / or condensate from the reformer is conveyed into the first tank at a filling level of 1 to 5%, preferably 1 to 3%, particularly preferably 1 to 2% of the tank volume of methanol.

[0045] The advantage of this mixing is that the toxicity of the mixture of water and methanol is sufficiently low so that the mixture can be released into the environment without further purification.

[0046] In a further embodiment of the invention, water is withdrawn from the second tank until the fill level is below 5% of the tank volume, preferably below 3% of the tank volume, particularly preferably below 2% of the tank volume, wherein the fill level is above 1% of the tank volume.

[0047] A minimum fill level prevents the pumps from running dry.

[0048] In a further embodiment of the invention, methanol is transported into the second tank to a fill level of 1 to 5%, preferably 1 to 3%, particularly preferably 1 to 2% of the tank volume. This refilling is usually carried out by refueling from outside, for example, in port or by a task force supply vessel.

[0049] This residual water content is not disruptive, as it does not significantly alter the water-to-methanol stoichiometry in the reformer. Furthermore, it represents an optimum balance between the maximum possible storage quantity of methanol and dry-run protection for the pumps.

[0050] The submarine according to the invention is explained in more detail below using an embodiment shown in the drawing. Fig. 1 schematic drawing

[0051] Fig. 1 shows the tank system of a submarine according to the invention. The tank system has eight tanks 10, 11, 12, 13, 14, 15, 16, 17, with one tank 13 being designed as a degassing tank. The eight tanks 10, 11, 12, 13, 14, 15, 16, 17 are designed according to shipbuilding technology, with four tanks arranged on the starboard side and four tanks on the port side. The seven tanks 10, 11, 12, 14, 15, 16, 17 can be filled with methanol or water. Before leaving the harbor, for example, six tanks 10, 11, 12, 14, 15, 16 are fully filled with methanol as fuel, while one tank 17 contains water, although the fill level is low.

[0052] The tanks 10, 11, 12, 14, 15, 16, 17 are connected to outlet valves 20, 21, 22, 24, 25, 26, 27. Furthermore, the tanks 10, 11, 12, 14, 15, 16, 17 are connected to inlet valves 30, 31, 32, 34, 35, 36, 37. The outlet valves 20, 21, 22, 24, 25, 26, 27 are connected to one another via an outlet connection 40, and the inlet valves 30, 31, 32, 34, 35, 36, 37 are connected to one another via an inlet connection 50. The outlet connection 40 is connected to the inlet connection 50 via a pump 60. This makes it possible to transfer methanol or water from any tank to any other tank, for example to trim the boat.

[0053] Methanol can be supplied to the inlet connection 50 via the refueling coupling 70 and to the tanks 10, 11, 12, 14, 15, 16, 17 via the inlet connection 50 and the inlet valves 30, 31, 32, 34, 35, 36, 37. The refueling coupling 70 is preferably arranged so that the submarine can be easily refueled; for example, the refueling coupling 70 is arranged in the turret.

[0054] Tanks 10, 11, 12, 14, 15, 16, 17 are connected to methanol discharge valves 80, 81, 82, 84, 85, 86, 87. The methanol discharge valves 80, 81, 82, 84, 85, 86, 87 are interconnected via a methanol discharge connection 90. This allows methanol to be pumped from tanks 10, 11, 12, 14, 15, 16, 17 to a first reformer 200 by means of a pump 100. In the example shown, methanol can be pumped to a second reformer 210 via a further pump 101. The redundant design increases the reliability of the energy supply.

[0055] Tanks 10, 11, 12, 14, 15, 16, 17 are connected to water drain valves 110, 111, 112, 114, 115, 116, 117. The water drain valves 110, 111, 112, 114, 115, 116, 117 are interconnected via a water drain connection 150. This allows water from tanks 10, 11, 12, 14, 15, 16, 17 to be pumped to a first reformer 20 by means of a pump 120. In the example shown, methanol can be pumped to a second reformer 230 via a further pump 121. The redundant design increases the reliability of the energy supply.

[0056] Inert gas can be supplied from an inert gas supply 130 into the tanks 10, 11, 12, 14, 15, 16, 17 via an inert gas line 132. An inert gas control system 134 is preferably used for control.

[0057] Tanks 140, 141, 142, 143, and 144 are connected by overflows 140, 141, 142, 143, and 144. The arrangement of overflows 140, 141, 142, 143, and 144 ensures that water and methanol cannot flow from one tank to the other, even when the submarine is tilted. For this purpose, an overflow connects two adjacent tanks at the top, each on the side opposite the adjacent tank.

[0058] Preferably, one outgoing connection below each tank can be closed by means of a manual shut-off valve 300.

[0059] To protect the entire system, filters 310 can be integrated at various locations. To allow replacement of the filters 310, a manual shut-off valve 300 is located at the inlet and outlet of the filter 310.

[0060] A defueling coupling 260 is provided for discharging water. This defueling coupling 260 is preferably arranged behind the outlet connection 40 and the pump 60 so that water, but also methanol, can be brought from the submarine via the outlet connection 40 and the pump 60 to empty the tanks 140, 141, 142, 143, 144.

[0061] It may be provided that methanol which has not been fully converted in the reformer can be recycled via a compound 270. Reference symbol

[0062] 10Tank 11Tank 12Tank 13Tank 14Tank 15Tank 16Tank 17Tank 20Outlet valve 21Outlet valve 22Outlet valve 24Outlet valve 25Outlet valve 26Outlet valve 27Outlet valve 30Inlet valve 31Inlet valve 32Inlet valve 34Inlet valve 35Inlet valve 36Inlet valve 37Inlet valve 40Outlet connection 50Inlet connection 60Pump 70Refueling coupling 80Methanol drain valve 81Methanol drain valve 82Methanol drain valve 84Methanol drain valve 85Methanol drain valve 86Methanol drain valve 87Methanol drain valve 90Methanol drain connection 100Pump 101Pump 110Water drain valve 111Water drain valve 112Water drain valve 114Water drain valve 115Water drain valve 116Water drain valve 117Water drain valve 120Pump 121Pump 130Inert gas supply 132Inert gas line 134Inert gas control 140Overflow 141Overflow 142Overflow 143Overflow 144Overflow 150Water drain connection 200to the first reformer 210to the second reformer 220to the first reformer 230to the second reformer 240from the fuel cell 250fromReformer 260, Defueling coupling 270, from reformer 300, manual shut-off valve 310, filter

Claims

1. A submarine having at least one first fuel cell and at least one first reformer, wherein the at least one first reformer is configured to produce hydrogen from methanol, wherein the submarine has at least one first tank (10, 11, 12, 13, 14, 15, 16, 17), a second tank (10, 11, 12, 13, 14, 15, 16, 17) and a third tank (10, 11, 12, 13, 14, 15, 16, 17), wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) being connectable to the reformer for fluid transport, wherein the second tank (10, 11, 12, 13, 14, 15, 16, 17) can be connected to the reformer for fluid transport, wherein the third tank (10, 11, 12, 13, 14, 15, 16, 17) can be connected to the reformer for fluid transport, wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) can be connected to the second tank (10, 11, 12, 13, 14, 15, 16, 17) for fluid transport, 17) for fluid transport, wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) is connectable to the third tank (10, 11, 12, 13, 14, 15, 16, 17) for fluid transport, wherein the second tank (10, 11, 12, 13, 14, 15, 16, 17) being connectable to the third tank (10, 11, 12, 13, 14, 15, 16, 17) for fluid transport, the first tank (10, 11, 12, 13, 14, 15, 16, 17) being connected on the underside to a first outlet valve (20, 21, 22, 23, 24, 25, 26, 27), the first tank (10, 11, 12, 13, 14, 15, 16, 17) being connected on the upper side to a first inlet valve (30, 31, 32, 33, 34, 35, 36, 37) at the top, that the second tank (10, 11, 12, 13, 14, 15, 16, 17) is to a second outlet valve (20, 21, 22, 23, 24, 25, 26, 27) at the bottom, that the second tank (10, 11, 12, 13, 14, 15, 16, 17) is connected at the top to a second inlet valve (30, 31, 32, 33, 34, 35, 36, 37), that the third tank (10, 11, 12, 13, 14, 15, 16, 17) is connected at the bottom to a third outlet valve (20, 21, 22, 23, 24, 25, 26, 27), and that the third tank (10, 11, 12, 13, 14, 15, 16, 17) is connected at the bottom to a third outlet valve (20, 21, 22, 23, 24, 25, 26, 27), 14, 15, 16, 17) is connected on the upper side to a third inlet valve (30, 31, 32, 33, 34, 35, 36, 37) , characterised in that the first outlet valve (20, 21, 22, 23, 24, 25, 26, 27), the second outlet valve (20, 21, 22, 23, 24, 25, 26, 27) and the third outlet valve (20, 21, 22, 23, 24, 25, 26, 27) are connected to a second outlet valve (20, 21, 22, 23, 24, 25, 26, 27), 21, 22, 23, 24, 25, 26, 27) are connected via an outlet connection (40), wherein the first inlet valve (30, 31, 32, 33, 34, 35, 36, 37), the second inlet valve (30, 31, 32, 33, 34, 35, 36, 37) and the third inlet valve (30, 31, 32, 33, 34, 35, 36, 37) are connected via an inlet connection (40), 37) are connected via an inlet connection (50), wherein the inlet connection (50) and the outlet connection (40) are connected to one another via a pump (60, 101, 101, 120, 121), wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) is connected on the underside to a first methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) on the underside, that the second tank (10, 11, 12, 13, 14, 15, 16, 17) is connected to a second methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) on the underside, and that the third tank (10, 11, 12, 13, 14, 15, 16, 17) is connected to a second methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) on the underside, 17) is connected on the underside to a third methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87), wherein the first methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87), the second methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) and the third methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) are connected to each other via a methanol discharge valve (80, 81, 82, 83, 84, 85, 86, 87), 86, 87) are connected via a methanol discharge connection (90), wherein the methanol discharge connection (90) is connected to the at least one first reformer via at least one first methanol discharge pump, wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) is connected on the underside to a first water drain valve (110, 111, 112, 113, 114, 115, 116, 117), in that the second tank (10, 11, 12, 13, 14, 15, 16, 17) is connected on the underside to a second water drain valve (110, 111, 112, 113, 114, 115, 116, 117), and in that the third tank (10, 11, 12, 13, 14, 116, 117) is connected on the underside to a second water drain valve (110, 111, 112, 113, 114, 115, 116, 117), 11, 12, 13, 14, 15, 16, 17) is connected at the underside to a third water drain valve (110, 111, 112, 113, 114, 115, 116, 117), wherein the first water drain valve (110, 111, 112, 113, 114, 115, 116, 117), the second water drain valve (110, 111, 112, 113, 114, 115, 116, 117) and the third water drain valve (110, 111, 112, 113, 114, 115, 116, 117) are connected at the underside to a third water drain valve (110, 111, 112, 113, 114, 115, 116, 117), 117) and the third water drain valve (110, 111, 112, 113, 114, 115, 116, 117) are connected via a water drain connection (150), wherein the water drain connection (150) is connected to the at least one first reformer via at least one first water drain pump.

2. Submarine according to claim 1, characterised in that the inlet connection (50) is connected to a refuelling coupling (70).

3. Submarine according to one of the preceding claims, characterised in that the first tank (10, 11, 12, 13, 14, 15, 16, 17), the second tank (10, 11, 12, 13, 14, 15, 16, 17) and the third tank (10, 11, 12, 13, 14, 15, 16, 17) are sealed off from the atmosphere of the submarine, wherein the submarine has a device for introducing inert gas into at least the first tank (10, 11, 12, 13, 14, 15, 16, 17), the second tank (10, 11, 12, 13, 14, 15, 16, 17) and the third tank (10, 11, 12, 13, 14, 15, 16, 17).

4. The submarine according to claim 3, characterised in that the inert gas is nitrogen, carbon dioxide, helium, neon, argon or a mixture thereof.

5. Submarine according to one of the preceding claims, characterised in that at least two tanks (10, 11, 12, 13, 14, 15, 16, 17) are arranged adjacent to one another, wherein the two tanks (10, 11, 12, 13, 14, 15, 16, 17) adjacent to one another are connected at the top to an overflow pipe, wherein the connections between the overflow pipe and the tanks (10, 11, 12, 13, 14, 15, 16, 17) are each connected on the side adjacent to the adjacent tank, 17) are connected at the top to an overflow pipe, the connections between the overflow pipe and the tanks (10, 11, 12, 13, 14, 15, 16, 17) being arranged in each case on the side opposite the neighbouring tank (10, 11, 12, 13, 14, 15, 16, 17).

6. Submarine according to one of the preceding claims, characterised in that the submarine has at least one degassing tank.

7. Submarine according to claim 6, characterised in that the submarine has a water separator on the cathode side, the water separator on the cathode side being connected to the cathode side of the at least one fuel cell, the water separator on the cathode side being connected to the degassing tank.

8. Submarine according to one of claims 6 or 7, characterised in that the outgassing tank is connected to the reformer for transferring condensate from the reformer to the outgassing tank.

9. Submarine according to one of claims 6 to 8, characterised in that the degassing tank is connected to the atmosphere of the submarine.

10. Submarine according to one of the preceding claims, characterised in that the submarine has a total of eight tanks (10, 11, 12, 13, 14, 15, 16, 17), four tanks (10, 11, 12, 13, 14, 15, 16, 17) being arranged on the starboard side and four tanks (10, 11, 12, 13, 14, 15, 16, 17) being arranged on the port side.

11. Submarine according to one of the preceding claims, characterised in that each tank (10, 11, 12, 13, 14, 15, 16, 17) has only one inlet for liquids on the upper side and one outlet for liquids on the lower side.

12. Method for operating a submarine according to one of the preceding claims, wherein at least one first tank (10, 11, 12, 13, 14, 15, 16, 17) is filled with methanol, wherein at least one second tank (10, 11, 12, 13, 14, 15, 16, 17) is filled with water, wherein methanol is conveyed from the first tank (10, 11, 12, 13, 14, 15, 16, 17) into at least one first reformer, wherein water is conveyed from the second tank (10, 11, 12, 13, 14, 15, 16, 17) into the at least one first reformer, wherein reaction water is conveyed from the fuel cell into the second tank (10, 11, 12, 13, 14, 15, 16, 17), wherein condensate is conveyed from the reformer into the second tank (10, 11, 12, 13, 14, 15, 16, 17).

13. Method according to claim 12, characterised in that methanol is removed from the first tank (10, 11, 12, 13, 14, 15, 16, 17) until the fill level is below 5% of the tank volume, preferably below of the tank volume, particularly preferably below of the tank volume, the fill level being above 1% of the tank volume.

14. Process according to claim 13, characterised in that methanol reaction water from the fuel cell and / or condensate from the reformer is conveyed into the first tank (10, 11, 12, 13, 14, 15, 16, 17) with a filling level of 1 to 5 %, preferably 1 to 3 %, particularly preferably 1 to 2 % of the tank volume.

15. Method according to one of claims 12 to 14, characterised in that water is removed from the second tank (10, 11, 12, 13, 14, 15, 16, 17) until the level is below 5 % of the tank volume, preferably below 3 % of the tank volume, particularly preferably below 2 % of the tank volume, the level being above 1 % of the tank volume.

16. Process according to claim 15, characterised in that water methanol is conveyed into the second tank (10, 11, 12, 13, 14, 15, 16, 17) with a filling level of 1 to 5%, preferably 1 to 3%, particularly preferably 1 to 2% of the tank volume.