Dry water electrolysis hydrogen gas producing device

Abstract

To provide a dry water electrolysis hydrogen gas producing device capable of smoothly producing dry water electrolysis hydrogen gas even at restart-up time.SOLUTION: Provided is a dry water electrolysis hydrogen gas producing device that includes a water electrolysis device, an absorber that brings the obtained wet water electrolysis hydrogen gas into contact with an absorbent liquid to obtain dry water electrolysis hydrogen gas and wet absorbent liquid, a storage device, a regenerator that brings the wet absorbent liquid into contact with dry hydrogen gas for regeneration (water electrolysis dry hydrogen gas) to obtain dry absorbent liquid and wet regeneration hydrogen gas, a diverter valve that circulates part of the dry water electrolysis hydrogen gas in the storage device side and the remainder in the regenerator side, a vacuum pump connected to the regenerator, and a three-way switching valve placed between the regenerator and the vacuum pump to switch the gas flow direction to either the vacuum pump side or the water electrolysis device side, when the device is stopped, the flow direction of the three-way switching valve is switched to the vacuum pump side, and when the device is started, the flow direction of the three-way switching valve is switched to the water electrolysis device side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to a dry water electrolysis hydrogen gas production apparatus. [Background technology]

[0002] Patent Documents 1 to 3 disclose dry water electrolysis hydrogen gas production equipment. The dry water electrolysis hydrogen gas production equipment is mainly composed of a water electrolysis device, an absorber, and a regenerator. The water electrolysis device electrolyzes water to generate wet water electrolysis hydrogen gas containing hydrogen and water vapor. The absorber brings the wet water electrolysis hydrogen gas into contact with an absorbing solution to obtain dry water electrolysis hydrogen gas and a wet absorbing solution. The regenerator removes moisture from the wet absorbing solution to regenerate the absorbing solution. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7116397 [Patent Document 2] JP 2018-51543 A [Patent Document 3] Patent Publication No. 2021-7938 Summary of the Invention [Problem to be solved by the invention]

[0004] In the regenerator, a part of the produced dry water electrolysis hydrogen gas may be used as dry hydrogen gas for regeneration and brought into contact with the wet absorbing solution to remove moisture from the wet absorbing solution and regenerate the absorbing solution.

[0005] However, when restarting the device, it is necessary to first introduce regeneration gas into the regenerator. In the configuration of the conventional technology, when part of the dry water electrolysis hydrogen gas is used as the dry hydrogen gas for regeneration, there is a problem that the dry water electrolysis hydrogen gas cannot be produced because there is no dry water electrolysis hydrogen gas at the start of the device.

[0006] In view of the above circumstances, a main object of the present disclosure is to provide a dry water electrolysis hydrogen gas production apparatus that can smoothly produce dry water electrolysis hydrogen gas even when restarted. [Means for solving the problem]

[0007] A first aspect of the present disclosure includes a water electrolysis device that electrolyzes water to generate wet water electrolysis hydrogen gas containing hydrogen and water vapor, an absorber that brings the wet water electrolysis hydrogen gas into contact with an absorbing liquid to obtain dry water electrolysis hydrogen gas with reduced humidity and a wet absorbing liquid that selectively absorbs water vapor, a storage device that stores the dry water electrolysis hydrogen gas, a regenerator that brings the wet absorbing liquid into contact with dry hydrogen gas for regeneration to obtain a dry absorbing liquid with reduced moisture content and wet hydrogen gas for regeneration with increased humidity, a liquid delivery pump that delivers the dry absorbing liquid to the absorber, and a distribution pump that distributes a portion of the dry water electrolysis hydrogen gas discharged from the absorber to the storage device side and the remainder to the regenerator side. a three-way switching valve disposed between the regenerator and the vacuum pump for switching the gas flow direction to either the vacuum pump side or the water electrolysis device side; and a boosting hydrogen pump disposed between the three-way switching valve and the water electrolysis device for boosting the pressure of wet regenerating hydrogen gas discharged from the regenerator and discharging it to the water electrolysis device side, wherein the dry hydrogen gas for regeneration is dry water electrolysis hydrogen gas discharged from the flow diverter valve, and the flow direction of the three-way switching valve is switched to the vacuum pump side when the device is stopped, and the flow direction of the three-way switching valve is switched to the water electrolysis device side when the device is started. Effect of the Invention

[0008] In the dry water electrolysis hydrogen gas production apparatus of the present disclosure, the flow direction of the three-way valve is switched to the vacuum pump side when the apparatus is stopped, and the flow direction of the three-way valve is switched to the water electrolysis apparatus side when the apparatus is started. Therefore, the entire absorbing solution can be sufficiently dried using the vacuum pump when the apparatus is stopped. Therefore, the dry water electrolysis hydrogen gas production apparatus of the present disclosure can smoothly produce dry water electrolysis hydrogen gas even when the apparatus is restarted. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram of a dry water electrolysis hydrogen gas production apparatus 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Dry water electrolysis hydrogen gas production equipment] The dry water electrolysis hydrogen gas production apparatus of the present disclosure is an apparatus for continuously producing dry water electrolysis hydrogen gas. The dry water electrolysis hydrogen gas production apparatus of the present disclosure will be described using a dry water electrolysis hydrogen gas production apparatus 1 as one embodiment.

[0011] Figure 1 shows a block diagram of a dry water electrolysis hydrogen gas production apparatus 1. As shown in Figure 1, the dry water electrolysis hydrogen gas production apparatus 1 mainly comprises a water electrolysis device 10 that electrolyzes water to produce wet water electrolysis hydrogen gas 20 containing hydrogen and water vapor, an absorber 30 that brings the wet water electrolysis hydrogen gas 20 into contact with an absorbing liquid (dry absorbing liquid 38) to obtain dry water electrolysis hydrogen gas 261 with reduced humidity and wet absorbing liquid 37 that selectively absorbs water vapor, a storage device 27 that stores the dry water electrolysis hydrogen gas 261, and a regenerator that brings the wet absorbing liquid 37 into contact with dry hydrogen gas for regeneration 262 (dry water electrolysis hydrogen gas 261) to obtain dry absorbing liquid 38 with reduced moisture content and wet hydrogen gas for regeneration 46 with increased humidity. The absorber 30 includes a storage device 27 that stores therein a gas supply unit 28, a liquid supply pump 35 that supplies the dry absorption liquid 38 to the absorber 30, a shunt valve 28 that distributes a portion of the dry water electrolysis hydrogen gas 261 discharged from the absorber 30 to the storage device 27 side and the remainder to the regenerator 34 side, a vacuum pump 40 connected to the regenerator 34, a three-way switching valve 42 that is disposed between the regenerator 34 and the vacuum pump 40 and switches the gas flow direction to the vacuum pump 40 side or the water electrolysis device 10 side, and a boosting hydrogen pump 44 that is disposed between the three-way switching valve 42 and the water electrolysis device 10 and boosts the pressure of the wet regeneration hydrogen gas 46 discharged from the regenerator 34 and discharges it to the water electrolysis device 10 side. Other members will be described later as necessary.

[0012] <Water electrolysis device 10> The water electrolysis device 10 electrolyzes water to generate wet-water electrolysis hydrogen gas 20 containing hydrogen and water vapor. The water electrolysis device 10 generates oxygen in addition to the wet-water electrolysis hydrogen gas 20. The form of the water electrolysis device 10 is not particularly limited, and examples thereof include an alkaline water electrolysis device, a solid polymer water electrolysis device, and a high-temperature steam electrolysis device.

[0013] Wet water electrolysis hydrogen gas 20 produced in the water electrolysis device 10 exchanges heat with cooling water 22 in the heat exchanger 21 and is adjusted to a desired temperature. Then, the flow rate of the wet water electrolysis hydrogen gas 20 is controlled by a flow rate controller 231 and sent to the absorber 30.

[0014] <Absorber 30> The absorber 30 brings the wet water electrolysis hydrogen gas 20 into contact with an absorbing liquid (dry absorbing liquid 38) to obtain a dry water electrolysis hydrogen gas 261 with reduced humidity and a wet absorbing liquid 37 that selectively absorbs water vapor. The absorber 30 functions as a gas-liquid separator, and the dry water electrolysis hydrogen gas 261 and the wet absorbing liquid 37 are separated into gas and liquid.

[0015] The absorbing liquid is a liquid absorbing medium having the property of absorbing and releasing water. For example, a mixed solution of an ionic liquid and an inorganic salt can be used. The absorbing liquid and the inorganic salt can be, for example, the absorbing liquid and the inorganic salt described in any one of Patent Documents 1 to 3.

[0016] As shown in Fig. 1, the absorbing liquid (dry absorbing liquid 38) is introduced from the top of the absorber 30, and the wet water electrolysis hydrogen gas 20 is introduced from the bottom of the absorber 30. They come into contact with each other inside the absorber 30. The absorbing liquid in the absorber 30 may be temperature controlled. For example, the temperature may be kept constant at 25°C. The pressure inside the absorber 30 may be controlled by providing a pressure regulating valve or the like.

[0017] Water vapor in the wet water electrolysis hydrogen gas 20 is absorbed by the absorbing liquid and reduced in amount. Hydrogen with reduced moisture content (dry water electrolysis hydrogen gas 261) is introduced into the trap 24 from the top of the absorber 30. The trap 24 can remove the absorbing liquid entrained by the hydrogen. The hydrogen that has passed through the trap 24 is passed through a dew point meter 25 to measure its dew point, and is sent to a diversion valve 28. The absorbing liquid that has absorbed moisture in the absorber 30 (wet absorbing liquid 37) is discharged from the bottom of the absorber 30, passes through a flow meter 31, a heat exchanger 321, and a heater 33, and is introduced into the regenerator 34.

[0018] <Flow Diverter Valve 28> The flow dividing valve 28 distributes a portion of the dry water electrolysis hydrogen gas 261 discharged from the absorber 30 to the storage device 27 side, and distributes the remainder to the regenerator 34 side. The distribution ratio of the dry water electrolysis hydrogen gas 261 can be appropriately set to a desired value.

[0019] The dry water electrolysis hydrogen gas 261 discharged from the flow dividing valve 28 to the storage device 27 side is sent to the storage device 27. The dry water electrolysis hydrogen gas 261 discharged from the flow dividing valve 28 to the regenerator 34 side is sent to the regenerator 34 via the flow meter 43. The dry water electrolysis hydrogen gas 261 sent to the regenerator 34 is used as dry hydrogen gas 262 for regeneration.

[0020] <Storage Unit 27> The storage device 27 stores the dry water electrolysis hydrogen gas 261. Such storage devices 27 are well known.

[0021] <Regenerator 34> The regenerator 34 brings the wet absorption liquid 37 into contact with the dry hydrogen gas for regeneration 262 (dry water electrolysis hydrogen gas 261) to obtain the dry absorption liquid 38 having a reduced moisture content and the wet hydrogen gas for regeneration 46 having an increased humidity.

[0022] As described above, the wet absorbing liquid 37 is heated by the heater 33 and adjusted to a predetermined temperature. For example, it may be adjusted to a constant temperature such as 100°C, 80°C, or 60°C. The flow rate of the dry hydrogen gas for regeneration 262 is not particularly limited, but for example, the wet absorbing liquid 37:dry hydrogen gas for regeneration 262 (volume ratio (normal pressure)) is preferably 1:300 to 1:1, and more preferably 1:200 to 1:1. The smaller the amount of the dry hydrogen gas for regeneration 262, the more the energy required for regeneration can be reduced, which is preferable.

[0023] 1, the wet absorbing liquid 37 is introduced from the top of the regenerator 34. The dry hydrogen gas for regeneration 262 is introduced from the bottom of the regenerator 34. Then, they come into contact with each other inside the regenerator 34. The moisture in the wet absorbing liquid 37 is absorbed by the dry hydrogen gas for regeneration 262 and decreases. The wet absorbing liquid 37 is dried to approximately the vapor pressure of the dry hydrogen gas for regeneration 262 introduced into the regenerator 34.

[0024] The obtained dry absorbing liquid 38 (regenerated absorbing liquid) is discharged from the bottom of the regenerator 34 and sent to the liquid sending pump 35. The obtained wet regenerating hydrogen gas 46 is sent to the three-way switching valve 42 via the trap 45.

[0025] <Liquid transfer pump 35> The liquid sending pump 35 sends the dry absorbing liquid 38 to the absorber 30. This allows the absorbing liquid to be circulated. During the liquid sending process, heat exchange is performed between the wet absorbing liquid 37 and the dry absorbing liquid 38 in the heat exchanger 321, and the amount of heat input to the heater 33 and the amount of heat exchanged in the heat exchanger 322 can be reduced.

[0026] <Vacuum Pump 40> The vacuum pump 40 is connected to the regenerator 34 and sucks in the air in the regenerator 34 and reduces the pressure. The sucked air is exhausted from an exhaust port 41. The vacuum pump 40 is mainly used when the device is stopped. The pressure can be reduced to, for example, -50 kPaG (gauge pressure). By reducing the pressure in this manner, the amount of moisture contained in the wet absorbent 37 can be reduced, and the absorbent (dry absorbent 38) can be regenerated.

[0027] <Three-way switching valve 42> The three-way switching valve 42 is disposed between the regenerator 34 and the vacuum pump 40, and switches the gas flow direction to either the vacuum pump 40 side or the water electrolysis device 10 side. The three-way switching valve 42 switches the gas flow direction to the vacuum pump 40 side when the device is stopped. Furthermore, the three-way switching valve 42 switches the gas flow direction to the water electrolysis device 10 side when the device is started. In other words, when the device is operating, the three-way switching valve 42 normally switches the gas flow direction to the water electrolysis device 10 side.

[0028] <Hydrogen booster pump 44> The hydrogen boost pump 44 is disposed between the three-way switching valve 42 and the water electrolysis device 10, and boosts the pressure of the wet regeneration hydrogen gas 46 discharged from the regenerator 34, and discharges it to the water electrolysis device 10 side. This enables the wet regeneration hydrogen gas 46 to be circulated to the water electrolysis device 10, the absorber 30, etc. As the hydrogen boost pump 44, a known pump can be used.

[0029] <Effects> In the dry water electrolysis hydrogen gas production apparatus 1, when the apparatus is shut down, the gas flow direction of the three-way switching valve 42 is switched from the water electrolysis apparatus 10 side to the vacuum pump 40 side. When the apparatus is shut down, water electrolysis is also stopped and dry hydrogen gas for regeneration is not produced. However, by using the vacuum pump 40, the wet absorbing solution 37 can be dried and the absorbing solution regenerated even when the apparatus is shut down. Therefore, when the apparatus is started up, the absorbing solution is sufficiently dry and dry water electrolysis hydrogen gas can be smoothly produced. Details will be described below.

[0030] (When the device is stopped) During normal operation, the flow direction of the three-way switching valve 42 is set to the water electrolysis device 10 side, and the wet regeneration hydrogen gas 46 circulates from the regenerator 34 to the water electrolysis device 10. When the device is stopped, the flow direction of the three-way switching valve 42 is switched from the water electrolysis device 10 side to the exhaust port 43 on the vacuum pump 40 side, and the valves on the inlet and outlet sides of the absorber 30 are closed. When the device is stopped, the water electrolysis device 10 is stopped and the supply of the wet water electrolysis hydrogen gas 20 is stopped. On the other hand, even when the device is stopped, the liquid delivery pump 35 continues to operate and the vacuum pump 40 is started. This allows the entire absorption liquid circulating in the absorber 30 and the regenerator 34 to be dried under reduced pressure. After the entire absorption liquid has been sufficiently dried, the valves on the inlet and outlet sides of the regenerator 34 are closed, and the liquid delivery pump 35 and the vacuum pump 40 are stopped.

[0031] (When restarting) The liquid delivery pump 35 is operated to start circulation of the absorption liquid between the regenerator 34 and the absorber 30. Next, the flow direction of the three-way switching valve 42 is switched from the vacuum pump 40 side to the water electrolysis device 10 side, and the inlet and outlet valves of the absorber 30 and the regenerator 34 are opened to start circulation of the wet water electrolysis hydrogen gas 20 and the dry hydrogen gas for regeneration 40.

[0032] (effect) In the configuration of the conventional technology, when a part of the dry water electrolysis hydrogen gas is used as the dry hydrogen gas for regeneration, there is a problem that the dry water electrolysis hydrogen gas cannot be produced at the start of the device because there is no dry water electrolysis hydrogen gas itself. In addition, even if the configuration of the conventional technology is used, the above problem does not occur if the hydrogen boost pump and the liquid delivery pump are always operated, including when there is no need to operate the regenerator, such as when water electrolysis is stopped, but this leads to a problem of wasting energy to operate the actuator all the time. In contrast, in the dry water electrolysis hydrogen gas production device 1, the vacuum pump 40 can be used when the device is stopped to sufficiently dry the entire absorption liquid, so that dry water electrolysis hydrogen gas can be produced smoothly without using the dry hydrogen gas for regeneration at the time of restart. In addition, when the device is stopped, all the actuators of the entire device can be stopped, which contributes to energy saving.

[0033] The dry water electrolysis hydrogen gas production apparatus of the present disclosure has been described above using one embodiment. The dry water electrolysis hydrogen gas production apparatus of the present disclosure can smoothly produce dry water electrolysis hydrogen gas when restarted.

[0034] [Dry water electrolysis hydrogen gas production method] The method for producing dry water electrolysis hydrogen gas according to the present disclosure is as follows: That is, a water electrolysis step of electrolyzing water to produce wet water electrolysis hydrogen gas containing hydrogen and water vapor, an absorption step of contacting the wet water electrolysis hydrogen gas with an absorbing liquid to obtain dry water electrolysis hydrogen gas with reduced humidity and a wet absorbing liquid that has selectively absorbed water vapor, a storage step of storing the dry water electrolysis hydrogen gas, a regeneration step of contacting the wet absorbing liquid with dry hydrogen gas for regeneration to obtain a dry absorbing liquid with reduced moisture content and wet regenerating hydrogen gas with increased humidity, a liquid delivery step of delivering the dry absorbing liquid to the absorption step, and a part of the wet water electrolysis hydrogen gas discharged from the absorption step to the storage step and the remainder to the storage step. The method for producing dry water electrolysis hydrogen gas includes a diversion step of sending the gas to a regeneration step, a reduced pressure drying step of drying the wet absorption liquid under reduced pressure, a pressurization step of pressurizing the wet hydrogen gas for regeneration discharged from the regeneration step and sending the gas to the absorption step, and a switching step of switching between the reduced pressure drying step and the pressurization step, wherein the dry hydrogen gas for regeneration is the dry water electrolysis hydrogen gas discharged from the diversion step, and either the reduced pressure drying step or the pressurization step is performed, and when the apparatus is stopped, the switching step switches the pressurization step to the reduced pressure drying step, and when the apparatus is started, the switching step switches the reduced pressure drying step to the pressurization drying step.

[0035] The method for producing dry water electrolysis hydrogen gas according to the present disclosure can be carried out using the above-mentioned dry water electrolysis hydrogen gas production device. According to the method for producing dry water electrolysis hydrogen gas according to the present disclosure, dry water electrolysis hydrogen gas can be produced smoothly at the start of the device. The details of the method for producing dry water electrolysis hydrogen gas according to the present disclosure have been described above, so a detailed description thereof will be omitted here. [Explanation of symbols]

[0036] 1. Water electrolysis hydrogen gas production equipment 10 Water electrolysis equipment 20 Wet water electrolysis hydrogen gas 21 Heat exchanger 22 Cooling water 231 Flow control meter 24 Trap 25 Dew point meter 261 Dry Water Electrolysis Hydrogen Gas 262 Dry hydrogen gas for regeneration 27 Storage Device 28 Diverter valve 30 Absorber 31 Flow meter 321 Heat exchanger 322 Heat Exchanger 33 Heater 34 Regenerator 35 Liquid delivery pump 36 Cooling water 37 Wet absorbent 38 Dry Absorbent 40 Vacuum Pump 41 Exhaust port 42 Three-way valve 43 Flow meter 44 Hydrogen boost pump 45 Trap 46 Hydrogen gas for wet regeneration

Claims

[Claim 1] a water electrolysis device that electrolyzes water to generate wet water electrolysis hydrogen gas containing hydrogen and water vapor; an absorber for contacting the wet water electrolysis hydrogen gas with an absorbing solution to obtain a dry water electrolysis hydrogen gas having reduced humidity and a wet absorbing solution that selectively absorbs the water vapor; A storage device for storing the dry water electrolysis hydrogen gas; a regenerator for contacting the wet absorbing liquid with dry hydrogen gas for regeneration to obtain a dry absorbing liquid having a reduced moisture content and a wet hydrogen gas for regeneration having an increased humidity; a liquid delivery pump that delivers the dry absorption liquid to the absorber; a dividing valve that distributes a portion of the dry water electrolysis hydrogen gas discharged from the absorber to the storage device side and distributes the remainder to the regenerator side; a vacuum pump connected to the regenerator; a three-way switching valve disposed between the regenerator and the vacuum pump for switching a flow direction of a gas to either the vacuum pump side or the water electrolysis device side; a pressure-boosting hydrogen pump that is disposed between the three-way switching valve and the water electrolysis device, and that pressurizes the wet regeneration hydrogen gas discharged from the regenerator and discharges the gas to the water electrolysis device side, the dry hydrogen gas for regeneration is the dry water electrolysis hydrogen gas discharged from the diverter valve, When the apparatus is stopped, the flow direction of the three-way switching valve is switched to the vacuum pump side, At the start of the device, the flow direction of the three-way switching valve is switched to the water electrolysis device side. Dry water electrolysis hydrogen gas production equipment.

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