DEVICE FOR DEGASSING FLOWABLE FLUIDS

Abstract

The invention relates to a device (10) for degassing flowable fluids, in particular liquids used for hydrogen storage, comprising: a desorber (12) which can be filled with fluid to be degassed and through which said fluid can flow; a circulation pump (48) for circulating the fluid during a degassing process in the desorber (12); a vacuum pump (38) for generating a vacuum in the desorber (12) during a filling process with fluid and for discharging the gas from the desorber (12) during the degassing process; at least one sensor (44a, 44b) for measuring the pressure in the desorber (12) and/or for time measurement; and a control unit which ends the degassing process when a predefined pressure is measured by the respective sensor (44a, 44b) and/or when a predefined dwell time of the fluid in the desorber (12) is measured.

Claims

1. A device (10) for degassing flowable fluids, in particular of liquids used to store hydrogen, comprising: a desorber (12) which can be filled with fluid to be degassed and which flows therethrough, a circulation pump (48) for circulating the fluid during a degassing operation in the desorber (12), a vacuum pump (38) for generating a negative pressure in the desorber (12) while it is filled with fluid and for the discharge of the gas from the desorber (12) during the degassing process, at least one sensor (44a, 44b) for measuring the pressure in the desorber (12) and/or for time measurements, and and a control unit, which terminates the degassing process when the respective sensors (44a, 44b) measure a predetermined pressure and/or a predetermined residence time of the fluid in the desorber (12) has been reached.

2. The device according to claim 1, characterized in that means are introduced into the desorber (12) for increasing the effective separating surface, preferably cylindrical, spherical or conical filling material of stainless steel, which at least partially fill the interior of the desorber (12).

3. The device according to claim 1, characterized in that a pre-separator (14) is installed between a fluid reservoir (16) and the desorber (12) and can be filled with fluid from the fluid reservoir (16).

4. The device according to claim 1, characterized in that a level sensor (26, 36) is provided in the pre-separator (14) and/or in the desorber (12), having at least one switching point (L3, L4; L1, L2, L6) assigned to the filling, emptying and/or degassing operation corresponding to the respective fill level of the fluid.

5. The device according to claim 1, characterized in that a gas port (54) connected to the pre-separator (14) and/or the desorber (12) is provided to equalize the pressure during emptying.

6. The device according to claim 1, characterized in that a gas outlet (40), which adjoins a valve device (42) and the vacuum pump (38), and a fluid outlet (52), which adjoins the circulation pump (48) and a valve device (50), are arranged at the desorber (12).

7. The device according to claim 1, characterized in that a valve device (24) and a further valve device (64) assigned to a further fluid supply line (66), preferably a stop-cock, are arranged between the pre-separator (14) assigned to one fluid supply line (18) and the desorber (12), and that the desorber (12), depending on the position of the further valve device (64), can be filled with fluid to be degassed via the fluid supply line (18) and the pre-separator or via the further fluid supply line (18).

8. Usage of the device (10) according to claim 1 for degassing flowable fluids, wherein fluid to be degassed is circulated in the desorber (12) by means of the circulation pump (48) during the degassing process and the gas is routed from the desorber (12) to the gas outlet (40) by the vacuum pump (38), and wherein the degassing process is terminated when a predetermined pressure is measured and/or at the end of a predetermined residence time of the fluid in the desorber (12).

9. The usage according to claim 8, characterized in that a further gas, preferably nitrogen, is routed for pressure equalization into the desorber (12) for an emptying process via a feed line (58), and then the degassed fluid is routed from the desorber (12) to the fluid outlet (52) by means of the circulation pump (48).

10. The usage according to claim 8, characterized in that a negative pressure in the desorber (12) is generated during the filling process by means of the vacuum pump (38) and then degassing fluid is routed from a fluid reservoir (16) into the desorber (12) via the fluid supply line (18) and the pre-separator (14) or via the further fluid supply line (66).

11. The usage according to claim 8, characterized in that in a first operating mode of the device (10) during the filling process a valve device (20) assigned to the fluid supply line (18) is opened and fluid to be degassed is routed from the fluid reservoir (16) into the pre-separator (14) until a first switching point (L4) of the assigned level sensor (26) is reached, the valve device (24) arranged between the pre-separator (14) and the desorber (12) is opened and the at least partially degassed fluid from the pre-separator (14) is routed into the desorber (12) until a second switching point (L6) of the assigned further level sensor (36) is reached, and that the valve device (20) upstream of the pre-separator (14) and the valve device (24) installed between the pre-separator (14) and the desorber (12) are closed.

12. The usage according to claim 8, characterized in that in a second operating mode of the device (10) during the filling process the valve device (24) upstream of the desorber (12) and assigned to the further fluid supply line (66) is opened and fluid to be degassed is routed from the fluid reservoir (16) into the desorber (12) until a second switching point (L6) of the assigned further level sensor (36) is reached, and the assigned valve device (24) is closed.

13. The usage according to claim 8, characterized in that the volume of fluid discharged (AVd3) from the desorber (12) during the emptying process matches the volume of fluid supplied (AVv) during the filling process.

14. The usage according to claim 8, characterized in that the fluid is a medium used for storing hydrogen, preferably dibenzyltoluene, from which hydrogen is separated by means of the device (10).

Description

[0029] The sole FIGURE shows a circuit diagram of the device according to the invention for the degassing of flowable fluids.

[0030] The figure shows a device 10 for degassing flowable fluids having a desorber 12 and a pre-separator 14. The pre-separator 14 is connected to a fluid reservoir 16 via a fluid supply line 18.

[0031] A first valve device 20 designed as a directional valve is arranged in the fluid supply line 18. In a first valve position of the first valve device 20, the fluid reservoir 16 is connected to the pre-separator 14 and in a second valve position to an emergency overflow 22. A second valve device 24 designed as a directional valve is arranged in a connecting line between the pre-separator 14 and the desorber 12. The assigned fluid path is open in a first valve position of the second valve device 24 and closed in a second valve position. A level sensor 26 having the switching points L3, L4 and L5 is arranged in the pre-separator 14. The gas emerging from the fluid to be degassed in the pre-separator 14 exits from the pre-separator 14 at a gas outlet 28. A check valve 30 is arranged in a connecting line from the pre-separator 14 to the gas outlet 28. Further, a pressure sensor 32 for measuring the pressure in the pre-separator 14 is provided at the pre-separator 14. The device 10 has a drip tray (not shown in the figure) having a float switch 34 disposed therein.

[0032] A further level sensor 36 having the switching points L1, L2 and L6 and in addition a vacuum pump 38 are arranged at the desorber 12 in a connecting line to a further gas outlet 40. A third valve device 42 designed as a directional valve is arranged between the desorber 12 and the vacuum pump 38. The assigned fluid port is open in a first valve position of the third valve device 42 and closed in a second valve position. Two further pressure sensors 44a and 44b are provided for measuring the pressure in the desorber 12. Further, a temperature sensor 46 is disposed at the desorber 12.

[0033] A fourth valve device 50 designed as a directional valve, the desorber 12 and a circulation pump 48 are arranged in a line circuit. In a first valve position of the fourth valve device 50, the line arriving from the circulation pump 48 is connected to a return line leading to the desorber 12 and thus the circuit for circulating the fluid flowing through the desorber 12 is closed. In a second valve position of the fourth valve device 50, the line arriving from the circulation pump 48 is connected to a fluid outlet 52 and thus the fluid path for discharging fluid from the desorber 12 to the fluid outlet 52 is opened. The vacuum pump 38 and the circulation pump 48 can each be driven by a motor M.

[0034] Furthermore, a gas port 54 leads to the desorber 12, wherein a fifth valve device 56 designed as a directional valve is arranged in a feed line 58 between the gas port 54 and the desorber 12. The fifth valve device 56 opens the fluid path in a first valve position via the supply line 58 and blocks it in a second valve position. A further supply line 60 leads from the gas port 54 to the pre-separator 14, wherein a further check valve 62 is arranged in the further supply line 60.

[0035] A further valve device 64 designed as a stop cock is arranged in the connecting line between the pre-separator 14 and the desorber 12, which valve device can be used to separate the pre-separator 14, and via a further fluid supply line 66 fluid can be routed from the fluid reservoir 16 into the desorber 12. In addition to the fluid outlet 52, a fluid discharge line 70, which can be closed and opened by a shut-off valve 68, is formed at the desorber 12.

[0036] The device 10, whose hydraulic circuit diagram can be seen in the figure, can be operated in three different operating modes, system operation, degassing from the fluid reservoir and manual operation. The control unit can be used to select individual operating modes.

[0037] The operating mode system operation requires that the further valve device 64 designed as a 3/2-way ball valve is set between the pre-separator 14 and the desorber 12 such that the pre-separator 14 can be connected to the desorber 12 in a fluid conveying manner. The flowable fluid, for instance a liquid hydrogen storage medium, is supplied to the preliminary switch 14 of the device 10 by overpressure in the assigned system. To this end, the first valve device 20 is energized and brought into the first valve position A-B shown in the figure. As soon as the fluid level corresponding to the second switching point L4 in the pre-separator 14 is detected by the level sensor 26, the second valve device 24 is opened and brought into the first valve position shown in the figure. The vacuum pump 38 generates a negative pressure in the desorber 12. As a result of the pressure difference between the pre-separator 14 and the desorber 12, the fluid flows into the desorber 12 when the second valve device 24 is open. The further check valve 62 arranged in the further supply line 60 keeps the pressure in the pre-separator 14 constant, to enable the pre-separator 14 to be emptied. Instead of the check valve 62, optionally a pressure regulator (not shown in the figure) may also be used. The second valve device 24 remains open during the filling process until the fluid level corresponding to the third switching point L6 is reached, as measured by the further level sensor 36 in the desorber 12. The gas delivered by the vacuum pump 38 from the desorber 12 is removed by a suitable venting system, which adjoins the further gas outlet 40.

[0038] If, in the event of a fault, the fluid cannot flow from the pre-separator 14 to the desorber 12, the fluid level corresponding to the third switching point L5 in the pre-separator 14 is reached. The third switching point L5 of the level sensor 26 corresponds to a maximum level of the fluid in the pre-separator 14. In this case, the power supply to the first valve device 20 is interrupted and the latter is brought into the second valve position A-C. The fluid flows untreated via the emergency overflow 22, preferably via a hose connected there, back into the fluid reservoir 16 or a separate collection tank.

[0039] The fluid to be degassed is circulated in the desorber 12 by the circulation pump 48. The circulation pump 48 only runs if the fluid level corresponding to the first switching point L1 is exceeded, as measured by the further level sensor 36 in the desorber 12. The first switching point L1 of the further level sensor 36 corresponds to a minimum level of the fluid in the desorber 12. When flowing through the desorber 12 and when flowing around the means to increase the effective separation area arranged in the desorber 12, gas exits the fluid, which gas is pumped out by the vacuum pump 38. The temperature sensor 46 measures the temperature of the exited gas, for instance hydrogen. If the temperature exceeds a value that is critical for the components used, for instance 40 Celsius, the device 10 is switched off for safety reasons as protection from explosions. In this case, the fluid flows back into the fluid reservoir 16 untreated, for instance, in to a tank, because the power supply of the first valve device 20 is also interrupted and it is brought into the second valve position A-C.

[0040] The fluid is circulated in the desorber 12 until the further pressure sensor 44b measures a preset target pressure for a set holding time and the set residence time of the fluid in the desorber 12 has elapsed. The control unit of the device 10 can be used to set the target pressure, the holding time and the residence time. In a particularly simple embodiment of the use of the device 10 for degassing a flowable fluid, the holding time can be omitted. The third valve device 42 connected upstream of the vacuum pump 38 is closed to terminate the degassing process, and then the fifth valve device 56 assigned to the gas port 54 is opened until the pressure in the desorber 12 is equalized. The pressure equalization is, for instance, performed using nitrogen from a nitrogen gas cylinder.

[0041] The fifth valve device 56 is closed again after a pressure of approximately 1000 mbar has been reached, measured by the further pressure sensor 44a in the desorber 12. If the pressure in the desorber 12 cannot be equalized, an error message to that end is output by the control unit. In an optional arrangement of a pressure regulator (not shown in the figure), the valve device 56 remains open and the pressure in the desorber 12 is kept constant by the pressure regulator.

[0042] Subsequent to the pressure equalization, the fourth valve device 50 is actuated and the fluid is pumped out of the desorber 12 via the circulation pump 48 until a fluid level corresponding to the second switching point L 2 is reached in the desorber 12.

[0043] Then, the fourth valve device 50 is returned to the first valve position shown A-B and the third valve device 42 assigned to the vacuum pump 38 is opened again. The cycle begins again when a fluid level corresponding to the second switching point L4 is reached again in the pre-separator 14.

[0044] In the second operating mode of degassing from the fluid reservoir 16, the device 10 itself draws the fluid to be degassed from the fluid reservoir 16, for instance a tank, into the desorber 12. To do so, the fluid reservoir 16 must be connected to the assigned inlet on the further valve device 64 by the further fluid supply line 66, which in particular is formed as a tube or hose. The second operating mode requires that the further valve device 64 designed as a 3/2-way ball valve [installed] between the pre-separator 14 and the desorber 12 is set in such a way that the fluid reservoir 16 is connected to the desorber 12 in a fluid conveying manner.

[0045] The filling, degassing and emptying processes in the desorber 12 proceed in accordance with the first operating mode. The first and second operating modes differ in the number of stages of separation. In the first operating mode, two separation stages, one in the pre-separator 14 and one in the desorber 12, are performed, whereas in the second operating mode only one separation stage is performed in the desorber 12. The pre-separator 14 is not used in the second operating mode and the switching points L3 and L4 of the assigned level sensor 26 are not active in this operating mode. In order to protect the pre-separator 14 from overfilling, the third switching point L5 is active in the second operating mode as well.

[0046] In the third operating mode, the valve devices 20, 24, 42, 46 and 50 assigned to the pre-separator 14, the desorber 15, 12, the further gas outlet 40, the gas port 54 and the fluid outlet 52 are switched manually. The vacuum pump 38 and the circulation pump 48 are also switched on and off manually.

[0047] Before the vacuum pump 38 is switched on, pressure equalization must be performed in the desorber 12. For this purpose, the third valve device 42 and the fifth valve device 56 are opened until the pressure equalization in the desorber 12 has been completed. The assigned measurement is performed via the further pressure sensor 44a. During startup of the vacuum pump 38, the two valve devices 42, 56 cannot be switched manually. The two preceding paragraphs relate to the use of a diaphragm pump, but not to the use of a rotary vane pump.

[0048] If the third switching point L6 is reached in the desorber 12, the second valve device 24 is closed and manual operation is bypassed in this respect. If the third switching point L5 is achieved in the pre-separator 14, the first valve device 20 is de-energized and the fluid 5 flows untreated back into the fluid reservoir 16 via the emergency overflow 22. The first valve device 20 is then in the second valve position A-C.

[0049] The float switch 34 arranged in the drip pan is activated upon the exit of fluid. In this case, the vacuum pump 38 is switched off and the second valve device 24 is closed and the first valve device 20 is de-energized. In order to prevent the desorber 12 from being overfilled, the second valve device 24 is closed when the fluid level corresponding to the third switching point L6 in the desorber 12 is reached. The level sensors 26, 36 are designed as openers at the pre-separator 14 and the desorber 12. In the event of a cable break of the level sensors 26, 36 or the sensors 32, 44a, 44b and 46, the device 10 is turned off.

[0050] Particularly preferably, a measurement data logging is provided in the apparatus 10 for degassing of flowable fluids, in particular when used for discharging a liquid hydrogen storage medium. The switching position of the valve devices 20, 24, 42, 50 and 56 can be recorded as a function of time. Also, the status of the motors M of the circulation pump 48 and the vacuum pump 38 may be recorded as a function of time. Further, the pressure and the temperature in the desorber 12 are recorded as measured data. Pressures above 400 mbar are measured using the first further pressure sensor 44a for the measuring range 0 to 1000 mbar, pressures below 400 mbar are measured using the second further pressure sensor 44b in the measuring range 0-400 mbar. The control unit of the device 10 can be used to set the measuring interval and the logging time. The recorded measurement data are advantageously stored in the device 10 and output via a media port, for instance a USB port as a CSV file, and transferred to an external storage medium. However, online measurement data logging during operation of the device 10 is also conceivable.

[0051] In the exemplary embodiment shown, the fluid volume AVv between the first and second switching point L3, L4 of the level sensor 26 in the pre-separator 14 is 10.51. The fluid volume AV.sub.D3 between the second and third switching point L2, L6 of the further level sensor 36 in the desorber 12 is also 10.51. Thus, the volume of fluid fed from the pre-separator 14 into the desorber 12 during filling matches the volume of fluid discharged from the desorber 12 during emptying. The fluid volume AV.sub.D2 between the first and second switching point L1, L2 of the further level sensor 36 is 1.101. The minimum level corresponding to the first switching point L1 of the further level sensor 36 AV.sub.DI is 1.051.

[0052] It goes without saying that, depending on the configuration of the device 10 and the container dimensions of the pre-separator 14 and the desorber 12, the corresponding fluid volumes vary and will be selected as needed.

[0053] As an alternative to the filling via the further valve device 64 and the second valve device 24 using a pressure difference, the desorber 12 can be filled using a pump, such as the circulation pump 48. In this variant of the inventive device 10 for degassing flowable fluids, a sixth valve device 72 is disposed in the fluid line routed from the desorber 12 to the circulation pump 48 and further connected to the pre-separator 14 in a fluid-conveying manner. In the first valve position of the sixth valve device 72 designed as a 3/2-way directional valve shown in the figure, the desorber 12 is connected to the circulation pump 48 during degassing according to the circulation operation. In the second valve position of the sixth valve device 72, the pre-separator 14 is connected to the circulation pump 48 in accordance with a filling process, such that the latter can pump fluid from the pre-separator 14 into the desorber 12 via the fourth valve device 50. A further fluid line branches off from the connecting line between the sixth valve device 72 and the circulation pump 48, which fluid line leads to the fifth valve device 50 in the direction leading to the fluid outlet 52 fluid line and includes a pressure relief valve 74 as a safety valve for the circulation pump 48.