Dry water electrolysis hydrogen gas producing apparatus

Abstract

To provide a dry water electrolysis hydrogen gas producing apparatus capable of suppressing malfunction of a vacuum pump.SOLUTION: Provided is a dry water electrolysis hydrogen gas producing apparatus including a water electrolysis device that electrolyzes water to generate humid water electrolysis hydrogen gas containing hydrogen and water vapor, an absorber that brings the humid water electrolysis hydrogen gas into contact with an absorbent liquid to obtain a humid absorbent liquid that selectively absorbs the dried water electrolysis hydrogen gas and water vapor with reduced humidity, a first regenerator that brings the humid absorbent liquid into contact with a drying gas for regeneration to obtain a preliminary dried absorbent liquid with reduced moisture content and a humid regeneration gas with increased humidity, a second regenerator that uses a vacuum pump to dehydrate the preliminary dried absorbent liquid under reduced pressure to obtain a dried absorbent liquid, and a liquid transfer pump that sends the dried absorbent liquid to the absorber.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, the wet absorbing liquid may be decompressed and dried using a vacuum pump. In a typical oil rotary vacuum pump, if the suction gas contains a condensable gas such as water vapor, it liquefies during compression, mixes with the oil, and remains in the pump. If such liquid remains in the pump, it can cause corrosion of parts and a decrease in the lubricity of the oil, leading to breakdowns. In addition, the water mixed with the oil evaporates again during decompression, making it difficult to reduce the ultimate pressure. In the regenerator, the wet absorbing liquid contains a large amount of water, so the amount of water is greater than the amount of water vapor that the vacuum pump can tolerate, and the above problems are likely to occur.

[0005] 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 suppress breakdowns of the vacuum pump. [Means for solving the problem]

[0006] A first aspect of the present disclosure is a dry water electrolysis hydrogen gas production apparatus including: a water electrolysis device that electrolyzes water to produce 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 first regenerator that brings the wet absorbing liquid into contact with a dry gas for regeneration to obtain a pre-dried absorbing liquid with reduced moisture content and a wet regenerating gas with increased humidity; a second regenerator that uses a vacuum pump to reduce pressure and dry the pre-dried absorbing liquid to obtain a dry absorbing liquid; and a liquid delivery pump that delivers the dry absorbing liquid to the absorber. Effect of the Invention

[0007] In the dry water electrolysis hydrogen gas production apparatus of the present disclosure, the wet absorbing solution is pre-dried in the first regenerator, and the obtained pre-dried wet absorbing solution is further dried in the second regenerator using a vacuum pump. Since the wet absorbing solution is pre-dried in this way, the amount of water vapor sucked into the vacuum pump in the second regenerator can be reduced. Therefore, the dry water electrolysis hydrogen gas production apparatus of the present disclosure can suppress breakdowns of the vacuum pump. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a dry water electrolysis hydrogen gas production apparatus 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [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.

[0010] A block diagram of the dry water electrolysis hydrogen gas production apparatus 1 is shown in Fig. 1. As shown in Fig. 1, the dry water electrolysis hydrogen gas production apparatus 1 mainly includes a water electrolysis device 10 that electrolyzes water to generate 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 a dry water electrolysis hydrogen gas 26 with reduced humidity and a wet absorbing liquid 37 that selectively absorbs water vapor, a first regenerator 341 that brings the wet absorbing liquid 37 into contact with a dry gas for regeneration 42 to obtain a pre-dried absorbing liquid 39 with reduced moisture content and a wet regenerating gas 48 with increased humidity, a second regenerator 342 that dries the pre-dried absorbing liquid 39 under reduced pressure using a vacuum pump 40 to obtain a dry absorbing liquid 38, and a liquid delivery pump 35 that delivers the dry absorbing liquid 38 to the absorber 30. Other members will be described later as necessary.

[0011] <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.

[0012] 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 23 and sent to an absorber 30.

[0013] <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 the dry water electrolysis hydrogen gas 26 with reduced humidity and the 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 26 and the wet absorbing liquid 37 are separated into gas and liquid.

[0014] 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.

[0015] 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.

[0016] 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 26) is introduced into the trap 24 from the top of the absorber 30. The trap 24 can remove the absorbing liquid entrained in 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 storage device 27. 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 first regenerator 341.

[0017] <1st regenerator 341> The first regenerator 341 brings the wet absorbing liquid 37 into contact with the dry gas for regeneration 42 to obtain the pre-dried absorbing liquid 39 having a reduced moisture content and the wet gas for regeneration 48 having an increased humidity.

[0018] 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 dry gas for regeneration 42 is not particularly limited, and examples thereof include air, nitrogen, and hydrogen. As the dry gas for regeneration 42, the dry water electrolysis hydrogen gas 26 obtained in the absorber 30 may be used. The flow rate of the dry gas for regeneration 42 is not particularly limited, and for example, the wet absorbing liquid 37:dry gas for regeneration 42 (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 gas for regeneration 42, the less the energy required for regeneration can be, and this is preferable.

[0019] 1, the wet absorbing liquid 37 is introduced from the top of the first regenerator 341. The regenerating dry gas 42 flows through a pipe from a regenerating gas supply source 47, exchanges heat with cooling water 44 in a heat exchanger 43, and is adjusted to a desired temperature. Then, the regenerating dry gas 42 passes through a flow meter 45 and is introduced from the bottom of the first regenerator 341. Then, they come into contact with each other inside the first regenerator 341.

[0020] The moisture in the wet absorbing liquid 37 is reduced by being absorbed by the dry gas for regeneration 42. The wet absorbing liquid 37 is dried to approximately the vapor pressure of the dry gas for regeneration 42 introduced into the first regenerator 341. The obtained pre-dried absorption liquid 39 is discharged from the lower part of the first regenerator 341 and introduced from the upper part into the second regenerator 342. The wet regenerating gas 48 with increased humidity is discharged from the upper part of the first regenerator 341 and is exhausted, for example, from the exhaust port 412.

[0021] <Second regenerator 342> The second regenerator 342 dries the pre-dried absorbing liquid 39 under reduced pressure using a vacuum pump 40 to obtain the dried absorbing liquid 38. The vacuum pump 40 draws in air in the second regenerator 342 and exhausts it from an exhaust port 411 via a trap 46. The reduced pressure can be, for example, -50 kPaG (gauge pressure). By drying under reduced pressure in this manner, the amount of moisture contained in the pre-dried absorbing liquid 39 is further reduced, and the absorbing liquid (dried absorbing liquid 38) can be regenerated.

[0022] As shown in FIG. 1, the regenerated absorbing liquid (dried absorbing liquid 38 ) is discharged from the bottom of the second regenerator 342 and sent to the liquid sending pump 35 .

[0023] <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. In addition, 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, so that the amount of heat input to the heater 33 and the amount of heat exchanged in the heat exchanger 322 can be reduced.

[0024] <Effects> In the dry water electrolysis hydrogen gas production apparatus 1, the wet absorbing solution 37 is pre-dried in the first regenerator 341, and the obtained pre-dried wet absorbing solution 39 is further dried in the second regenerator 342 using the vacuum pump 40 to obtain the dry absorbing solution 38. In this way, in the dry water electrolysis hydrogen gas production apparatus 1, the wet absorbing solution 37 is pre-dried, so that the amount of water vapor sucked into the vacuum pump 40 in the second regenerator 342 can be reduced. Therefore, the dry water electrolysis hydrogen gas production apparatus 1 can suppress breakdowns of the vacuum pump. As a result, the frequency and cost of replacing the vacuum pump 40 can be reduced.

[0025] 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 continuously produce dry water electrolysis hydrogen gas while suppressing failure of the vacuum pump.

[0026] [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, the method for producing dry water electrolysis hydrogen gas includes 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 absorption liquid (dry absorption liquid) to obtain dry water electrolysis hydrogen gas with reduced humidity and a wet absorption liquid that has selectively absorbed water vapor, a first regeneration step of contacting the wet absorption liquid with a dry gas for regeneration to obtain a pre-dried absorption liquid with reduced moisture content and a wet regeneration gas with increased humidity, a second regeneration step of drying the pre-dried absorption liquid under reduced pressure using a vacuum pump to obtain a dry absorption liquid, and a liquid delivery step of delivering the dry absorption liquid to the absorption step.

[0027] The method for producing hydrogen gas by dry water electrolysis according to the present disclosure can be carried out using the above-mentioned dry water electrolysis hydrogen gas production device. The method for producing hydrogen gas by dry water electrolysis according to the present disclosure can prevent failure of the vacuum pump. The details of the method for producing hydrogen gas by dry water electrolysis according to the present disclosure have been described above, so a detailed description thereof will be omitted here. [Explanation of symbols]

[0028] 1. Water electrolysis hydrogen gas production equipment 10 Water electrolysis equipment 20 Wet water electrolysis hydrogen gas 21 Heat exchanger 22 Cooling water 23 Flow control meter 24 Trap 25 Dew point meter 26 Dry water electrolysis hydrogen gas 27 Storage Device 30 Absorber 31 Flowmeter 321 Heat exchanger 322 Heat Exchanger 33 Heater 341 1st regenerator 342 2nd regenerator 35 Liquid delivery pump 36 Cooling water 37 Wet absorbent 38 Dry Absorbent 39 Pre-dried absorbent 40 Vacuum Pump 411 Exhaust port 412 Exhaust port 42 Dry gas for regeneration 43 Heat exchanger 44 Cooling water 45 Flow meter 46 Trap 47 Regeneration gas supply source 48 Wet regeneration gas

Claims

[Claim 1] 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 solution to obtain a dry water electrolysis hydrogen gas having reduced humidity and a wet absorbing solution that selectively absorbs the water vapor; a first regenerator for contacting the wet absorbing liquid with a dry gas for regeneration to obtain a pre-dried absorbing liquid having a reduced moisture content and a wet gas for regeneration having an increased humidity; a second regenerator for drying the pre-dried absorbing liquid under reduced pressure using a vacuum pump to obtain a dried absorbing liquid; A liquid sending pump that sends the dry absorption liquid to the absorber. Dry water electrolysis hydrogen gas production equipment.

Images