Dehumidifier, dehumidification method, and computer program

Abstract

This invention provides a technology to improve the dehumidification efficiency of dehumidifiers. [Solution] The dehumidifier comprises a first absorption tower that absorbs water contained in the target gas into a first absorbent liquid, a first regeneration tower connected to the first absorption tower that releases water from the first absorbent liquid flowing in from the first absorption tower, and a first regeneration tower that returns the first absorbent liquid from which water has been released back to the first absorption tower, a second absorption tower connected to the first regeneration tower that absorbs the water released from the first absorbent liquid in the first regeneration tower into a second absorbent liquid, and a second regeneration tower connected to the second absorption tower that releases water from the second absorbent liquid flowing in from the second absorption tower, and a second regeneration tower that returns the second absorbent liquid from which water has been released back to the second absorption tower, wherein the equilibrium dew point of the second absorbent liquid in the second regeneration tower is greater than the equilibrium dew point of the first absorbent liquid in the first regeneration tower.

Description

[Technical Field]

[0001] The present invention relates to a dehumidifying device, a dehumidifying method, and a computer program. Regarding. [Background technology]

[0002] Dehumidifiers for adjusting the humidity of gases have been known for some time (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-7938 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, even with prior art such as Patent Document 1, there was still room for improvement in techniques for improving the dehumidification efficiency of dehumidifiers.

[0005] The present invention was made to solve the above-mentioned problems and aims to provide a technology to improve the dehumidification efficiency in a dehumidifying device. [Means for solving the problem]

[0006] The present invention has been made to solve at least some of the above-mentioned problems and can be realized in the following forms.

[0007] (1) According to one embodiment of the present invention, a dehumidification device is provided. This dehumidification device comprises: a first absorption tower that absorbs water contained in a target gas into a first absorbent liquid; a first regeneration tower connected to the first absorption tower that releases water from the first absorbent liquid flowing in from the first absorption tower, and returns the first absorbent liquid from which water has been released back to the first absorption tower; a second absorption tower connected to the first regeneration tower that absorbs the water released from the first absorbent liquid in the first regeneration tower into a second absorbent liquid; and a second regeneration tower connected to the second absorption tower that releases water from the second absorbent liquid flowing in from the second absorption tower, and returns the second absorbent liquid from which water has been released back to the second absorption tower, wherein the equilibrium dew point of the second absorbent liquid in the second regeneration tower is greater than the equilibrium dew point of the first absorbent liquid in the first regeneration tower.

[0008] In this configuration, the dehumidifier is set up with multiple stages of absorption and regeneration towers. In the preceding first regeneration tower, water released from the first absorbent is absorbed by the second absorbent in the subsequent second absorption tower. In such a multi-stage dehumidifier, the equilibrium dew point of the second absorbent in the subsequent second regeneration tower is higher than the equilibrium dew point of the first absorbent in the preceding first regeneration tower. As a result, the amount of water released from the second absorbent per unit time in the second regeneration tower is greater than the amount of water released from the first absorbent per unit time in the first regeneration tower. Therefore, the water removed from the target gas in the preceding first absorption tower can be efficiently released to the outside of the dehumidifier, thereby improving the dehumidification efficiency of the dehumidifier.

[0009] (2) The dehumidifier of the above configuration further comprises a connecting channel connected to the first regeneration tower and the second absorption tower, through which water released from the first absorbent liquid in the first regeneration tower flows, a pressure detection unit for detecting the pressure in the connecting channel, a pump for reducing the pressure in the connecting channel, and a control unit for controlling the pump using the pressure in the connecting channel detected by the pressure detection unit, wherein the control unit may drive the pump to reduce the pressure in the connecting channel when the pressure in the connecting channel exceeds a preset threshold. With this configuration, water released from the first absorbent liquid in the first regeneration tower flows through the connecting channel and moves to the second absorption tower. The control unit drives the pump to reduce the pressure in the connecting channel when the pressure in the connecting channel exceeds a preset threshold. This reduces the amount of foreign matter that may hinder the movement of water in the connecting channel, such as gas molecules other than water, making it easier for water to move from the first regeneration tower to the second absorption tower. Therefore, the dehumidification efficiency of the dehumidifier can be further improved.

[0010] (3) The dehumidifier of the above configuration further comprises a circulating gas flow path connected to the first regeneration tower and the second absorption tower, through which circulating gas flows between the first regeneration tower and the second absorption tower, and a compressor connected to the circulating gas flow path, wherein the first regeneration tower releases water from the first absorbent liquid by incorporating the water of the first absorbent liquid into the circulating gas, and the second absorption tower may absorb the water contained in the circulating gas into the second absorbent liquid. With this configuration, the circulating gas circulating between the first regeneration tower and the second absorption tower can promote the release of water from the first absorbent liquid in the first regeneration tower. The circulating gas containing water released from the first absorbent liquid in the first regeneration tower is forcibly moved to the second absorption tower by the compressor, and the contained water is absorbed into the second absorbent liquid in the second absorption tower. This makes it possible to efficiently send the water absorbed by the first absorbent liquid from the target gas in the first absorption tower to the second absorption tower. Therefore, the dehumidification efficiency of the dehumidifier can be further improved.

[0011] (4) The dehumidifier of the above form may further include a purge gas supply unit that supplies the target gas from which at least a portion of the contained water has been removed in the first absorption tower to the second regeneration tower and brings it into contact with the second absorbent liquid, thereby releasing water from the second absorbent liquid as a purge gas, the purge gas supply unit being connected to the second regeneration tower and the first absorption tower and having a purge gas flow path that returns the purge gas from which water has been released from the second absorbent liquid in the second regeneration tower to the first absorption tower, and a cooler connected to the purge gas flow path that cools the purge gas flowing through the purge gas flow path. With this configuration, in the second regeneration tower, water is released from the second absorbent liquid using the target gas from which water has been absorbed in the first absorbent liquid in the first absorption tower, i.e., a relatively dry gas, so that water can be released from the second absorbent liquid efficiently. The purge gas from which water has been released from the second absorbent liquid is cooled by the cooler connected to the purge gas flow path, so that at least a portion of the absorbed water is removed, and then it returns to the first absorption tower. In this way, the purge gas used to release water from the second absorbent liquid can be circulated within the dehumidifier, reducing or eliminating the need for externally introduced purge gas. This further improves the dehumidification efficiency of the dehumidifier.

[0012] (5) In the dehumidifier of the above form, the target gas may be a mixed gas containing hydrogen and water produced by a water electrolysis device. With this configuration, the dehumidifier uses a mixed gas containing hydrogen and water produced by a water electrolysis device as the target gas and absorbs the water contained in the mixed gas with the first absorbent liquid. This makes it possible to effectively utilize the hydrogen produced by the water electrolysis device.

[0013] (6) In the dehumidifier of the above form, the first absorbent liquid and the second absorbent liquid may be ionic liquids. With this configuration, since the first absorbent liquid and the second absorbent liquid are ionic liquids with almost no vapor pressure, mixing of the first absorbent liquid and the second absorbent liquid can be suppressed as water moves from the first regeneration tower to the second absorption tower. Therefore, the dehumidification efficiency of the dehumidifier can be maintained.

[0014] (7) According to another embodiment of the present invention, a dehumidification method using a dehumidifier is provided. This dehumidification method comprises: a first absorption step in which a first absorption tower absorbs water contained in a target gas into a first absorbent liquid; a first regeneration step in which water is released from the first absorbent liquid that has flowed from the first absorption tower to a first regeneration tower, and the first absorbent liquid from which water has been released is returned to the first absorption tower; a second absorption step in which the water released from the first absorbent liquid in the first regeneration tower is absorbed into a second absorbent liquid in a second absorption tower; and a second regeneration step in which water is released from the second absorbent liquid that has flowed from the second absorption tower to a second regeneration tower, and the second absorbent liquid from which water has been released is returned to the second absorption tower, wherein the equilibrium dew point of the second absorbent liquid in the second regeneration tower is greater than the equilibrium dew point of the first absorbent liquid in the first regeneration tower. With this configuration, the equilibrium dew point of the second absorbent liquid that releases water in the second regeneration step is higher than the equilibrium dew point of the first absorbent liquid that releases water in the first regeneration step. As a result, the amount of water released per unit time from the second absorbent is greater than the amount of water released per unit time from the first absorbent. Therefore, the water removed from the target gas by the first absorption process can be efficiently released to the outside of the dehumidifier, thereby improving the dehumidification efficiency of the dehumidifier.

[0015] (7) According to yet another embodiment of the present invention, a computer program is provided which causes a computer to perform dehumidification of a target gas using a dehumidification device. This computer program causes the computer to perform the following functions in a first absorption tower: a first absorption function which causes water contained in the target gas to be absorbed into a first absorbent liquid; a first regeneration function which causes water to be released from the first absorbent liquid that has flowed from the first absorption tower to a first regeneration tower, and returns the first absorbent liquid that has released water back to the first absorption tower; a second absorption function which causes the water released from the first absorbent liquid in the first regeneration tower to be absorbed into a second absorbent liquid in a second absorption tower; and a second regeneration function which causes water to be released from the second absorbent liquid that has flowed from the second absorption tower to a second regeneration tower, and returns the second absorbent liquid that has released water back to the second absorption tower, wherein the equilibrium dew point of the second absorbent liquid in the second regeneration tower is greater than the equilibrium dew point of the first absorbent liquid in the first regeneration tower. In this configuration, the equilibrium dew point of the second absorbent, which releases water through the second regeneration function, is higher than the equilibrium dew point of the first absorbent, which releases water through the first regeneration function. As a result, the amount of water released per unit time from the second absorbent is greater than the amount of water released per unit time from the first absorbent. Therefore, the water removed from the target gas by the first absorption function can be efficiently released to the outside of the dehumidifier, thereby improving the dehumidification efficiency of the dehumidifier.

[0016] Furthermore, the present invention can be realized in various forms, for example, as a system including a dehumidifier, a control method for such a system and device, a computer program for causing the dehumidification of gas in such a system and device, a server device for distributing the computer program, and a non-temporary storage medium storing the computer program. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic diagram showing the general configuration of the dehumidifier according to the first embodiment. [Figure 2] This is the first diagram illustrating the operation of the dehumidifier according to the first embodiment. [Figure 3]It is a second figure for explaining the operation of the dehumidifying device of the first embodiment. [Figure 4] It is a schematic diagram showing the schematic configuration of the dehumidifying device of the comparative example. [Figure 5] It is a figure for explaining the operation of the dehumidifying device of the comparative example. [Figure 6] It is a schematic diagram showing the schematic configuration of the dehumidifying device of the second embodiment. [Figure 7] It is a figure for explaining the operation of the dehumidifying device of the second embodiment. [Figure 8] It is a figure for explaining the schematic configuration of the dehumidifying device of the comparative example. [Figure 9] It is a figure for explaining the operation of the dehumidifying device of the comparative example. [Figure 10] It is a schematic diagram showing the schematic configuration of the dehumidifying device of the third embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0018] <First Embodiment> FIG. 1 is a schematic diagram showing the schematic configuration of the dehumidifying device of the present embodiment. The dehumidifying device 1 performs dehumidification of gas by absorbing water such as water vapor and water droplets contained in the gas into the absorption liquid by a gas-liquid contact method. The dehumidifying device 1 of the present embodiment dehumidifies the hydrogen gas generated by a water electrolysis device not shown. The hydrogen gas generated by the water electrolysis device contains water as a raw material that was supplied to the water electrolysis device but not electrolyzed. That is, the hydrogen gas is a mixed gas containing hydrogen and water. The dehumidifying device 1 includes a first absorption tower 11, a first regeneration tower 12, a first temperature control unit 13, a second absorption tower 21, a second regeneration tower 22, a second temperature control unit 23, a connection flow path 31, and a control unit 40. The dehumidifying device 1 of the present embodiment is a two-stage dehumidifying device in which a combination of the first absorption tower 11 and the first regeneration tower 12 and a combination of the second absorption tower 21 and the second regeneration tower 22 are connected step by step.

[0019] Here, we will explain the absorbent liquid used in the dehumidifier 1. Examples of absorbent liquids used in the dehumidifier 1 to absorb water contained in hydrogen gas include ethylene glycols and ionic liquids. The partial pressure of water vapor at which gas-liquid equilibrium occurs changes depending on the temperature of the absorbent liquid itself and the water content of the absorbent liquid. Specifically, if the partial pressure of water vapor is higher than the equilibrium water vapor pressure, the absorbent liquid absorbs water to reach the equilibrium water vapor pressure, and if the partial pressure of water vapor is lower than the equilibrium water vapor pressure, it releases water until it reaches the equilibrium water vapor pressure. Therefore, if there is sufficient contact between the gas and the absorbent liquid and gas-liquid equilibrium is reached, the water vapor pressure after dehumidification will be equal to the equilibrium water vapor pressure of the absorbent liquid. When the water content in the absorbent liquid decreases (the absorbent liquid becomes more concentrated or leaner in water) or when the temperature of the absorbent liquid decreases, the water vapor absorption performance improves and the equilibrium water vapor pressure decreases. On the other hand, if the water content in the absorbent solution increases (the absorbent solution becomes diluted or water-rich), or if the temperature of the absorbent solution rises, the water vapor absorption performance decreases, and the equilibrium water vapor pressure for water increases. The dehumidifier 1 of this embodiment utilizes this property of the absorbent solution to dehumidify hydrogen gas.

[0020] The dehumidifier 1 of this embodiment uses a first absorbent liquid circulating between the first absorption tower 11 and the first regeneration tower 12, and a second absorbent liquid circulating between the second absorption tower 21 and the second regeneration tower 22. In this embodiment, the first absorbent liquid and the second absorbent liquid are the same type of ionic liquid, but the water content of the second absorbent liquid is set to be greater than that of the first absorbent liquid. Note that the first absorbent liquid and the second absorbent liquid do not have to be the same type of ionic liquid; they may be different types of ionic liquids. The relationship between the first absorbent liquid and the second absorbent liquid is such that the equilibrium dew point of the second absorbent liquid in the second regeneration tower is greater than the equilibrium dew point of the first absorbent liquid in the first regeneration tower, as will be described later.

[0021] The first absorption tower 11 contains packing material 11a, such as metal or ceramic, inside. Examples of packing material 11a include Raschig rings, Dixon packing, and woven mesh. The first absorption tower 11 is connected to a first absorption liquid channel 14a through which the first absorption liquid from the first regeneration tower 12 (described later) flows, and a first absorption liquid channel 14b through which the first absorption liquid from the first absorption tower 11 flows, as well as a hydrogen gas channel 5. Hydrogen gas containing hydrogen and water, supplied from a water electrolysis device (not shown), flows through the hydrogen gas channel 5. The hydrogen gas channel 5 is equipped with a flow control valve 5a that controls the flow rate of hydrogen gas flowing through the hydrogen gas channel 5. The flow control valve 5a controls the flow rate of hydrogen gas flowing into the first absorption tower 11 in response to commands from an electrically connected control unit 40. The hydrogen gas corresponds to the "target gas" in the claims.

[0022] The first regeneration tower 12 contains packing material 12a, such as metal or ceramics, inside. Examples of packing material 12a include Raschig rings, Dixon packing, and woven mesh. In addition to the first absorbent liquid channel 14b and the first absorbent liquid channel 14a, the first regeneration tower 12 is connected to a connecting channel 31 that connects to the second absorption tower 21. A liquid transfer pump 14c is provided in the first absorbent liquid channel 14a connected to the first regeneration tower 12. The liquid transfer pump 14c pumps the first absorbent liquid in the first regeneration tower 12 toward the first absorption tower 11 so that the first absorbent liquid circulates between the first absorption tower 11 and the first regeneration tower 12.

[0023] The first temperature control unit 13 comprises a cooler 13a, a heater 13b, and a heat exchanger 13c. The cooler 13a is provided in the first absorbent fluid channel 14a. The cooler 13a cools the first absorbent fluid flowing through the first absorbent fluid channel 14a using a refrigerant or the like. The heater 13b is provided in the first absorbent fluid channel 14b. The heater 13b heats the first absorbent fluid flowing through the first absorbent fluid channel 14b using a heater or the like. The heat exchanger 13c crosses the first absorbent fluid channel 14a and the first absorbent fluid channel 14b, thereby performing heat exchange between the first absorbent fluid before it is cooled by the cooler 13a and the first absorbent fluid before it is heated by the heater 13b. The first temperature control unit 13 adjusts the temperature of the first absorbent fluid so that the temperature of the first absorbent fluid in the first regeneration tower 12 is higher than the temperature of the first absorbent fluid in the first absorption tower 11.

[0024] The second absorption tower 21 contains packing material 21a, such as metal or ceramic, inside. Examples of packing material 21a include Raschig rings, Dixon packing, and woven mesh. In addition to the second absorption liquid channel 24a through which the second absorption liquid from the second regeneration tower 22 (described later) flows, and the second absorption liquid channel 24b through which the second absorption liquid from the second absorption tower 21 flows, the second absorption tower 21 is also connected to a connecting channel 31 that connects to the first regeneration tower 12.

[0025] The second regeneration tower 22 temporarily stores the second absorbent liquid. In addition to the second absorbent liquid flow path 24b and the second absorbent liquid flow path 24a, the second regeneration tower 22 is connected to a purge gas flow path 6 through which a relatively dry gas, the purge gas, flows. The purge gas flow path 6 is equipped with a flow control valve 6a that controls the flow rate of the purge gas flowing through the purge gas flow path 6. The flow control valve 6a controls the flow rate of the purge gas flowing into the second regeneration tower 22 in response to a command from the electrically connected control unit 40. A liquid transfer pump 24c is provided in the second absorbent liquid flow path 24a connected to the second regeneration tower 22. The liquid transfer pump 24c pressurizes the second absorbent liquid in the second regeneration tower 22 toward the second absorbent tower 21 so that the second absorbent liquid circulates between the second absorption tower 21 and the second regeneration tower 22.

[0026] The second temperature control unit 23 comprises a cooler 23a, a heater 23b, and a heat exchanger 23c. The cooler 23a is provided in the second absorbent fluid channel 24a. The cooler 23a cools the second absorbent fluid flowing through the second absorbent fluid channel 24a using a refrigerant or the like. The heater 23b is provided in the second absorbent fluid channel 24b. The heater 23b heats the second absorbent fluid flowing through the second absorbent fluid channel 24b using a heater or the like. The heat exchanger 23c crosses the second absorbent fluid channel 24a and the second absorbent fluid channel 24b, thereby performing heat exchange between the second absorbent fluid before it is cooled by the cooler 23a and the second absorbent fluid before it is heated by the heater 23b. The second temperature control unit 23 adjusts the temperature of the second absorbent fluid so that the temperature of the second absorbent fluid in the second regeneration tower 22 is higher than the temperature of the second absorbent fluid in the second absorption tower 21.

[0027] The connecting channel 31 connects to the first regeneration tower 12 and the second absorption tower 21. An exhaust channel 32 is connected to the connecting channel 31, and a pump 33 is provided in the exhaust channel 32 to reduce the pressure inside the connecting channel 31 via the exhaust channel 32. The connecting channel 31 is provided with a pressure detection unit 34 that detects the pressure inside the connecting channel 31. The pressure detection unit 34 outputs the detected pressure to a control unit 40 which is electrically connected.

[0028] The control unit 40 is a computer comprising ROM, RAM, and CPU. The control unit 40 is electrically connected to the flow control valves 5a and 6a, the pump 33, etc. The control unit 40 controls each part of the dehumidifier 1 and dehumidifies hydrogen gas by loading a computer program stored in ROM (Read Only Memory) (not shown) into RAM (Random Access Memory) and executing it.

[0029] Next, a dehumidification method using the dehumidifier 1 of this embodiment will be described. In the dehumidification method using the dehumidifier 1 of this embodiment, as preparation for dehumidification, the control unit 40 uses the exhaust passage 32 and the pump 33 to reduce the pressure so that only water vapor is present in the first regeneration tower 12, the second absorption tower 21, and the connecting passage 31. As described above, the first absorbent liquid and the second absorbent liquid used in the dehumidifier 1 of this embodiment are ionic liquids and therefore have almost no vapor pressure. As a result, even when the pressure is reduced using the pump 33, the first absorbent liquid and the second absorbent liquid hardly evaporate, so the vapor pressure in the first regeneration tower 12, the second absorption tower 21, and the connecting passage 31 is in accordance with the equilibrium pressure of the first absorbent liquid and the second absorbent liquid. In this embodiment, the water content of the second absorbent liquid is greater than that of the first absorbent liquid. As a result, the relationship between the equilibrium pressure Pe12 of the first absorbent in the first regeneration tower 12, the pressure P31 of the connecting channel 31, and the equilibrium pressure Pe21 in the second absorption tower 21 is given by the following equation (1). Consequently, the water (water vapor) in the first regeneration tower 12 will spontaneously move into the second absorption tower 21 through the connecting channel 31. Pe12>P31>Pe21 ···(1)

[0030] In the dehumidification method using the dehumidifier 1 of this embodiment, the relationship between the equilibrium pressure Pe12 of the first absorbent in the first regeneration tower 12 and the equilibrium pressure Pe22 of the second absorbent in the second regeneration tower 22 is given by the following equation (2), due to the temperature adjustment of the first absorbent by the first temperature control unit 13 and the temperature adjustment of the second absorbent by the second temperature control unit 23. Pe12 <Pe22 ···(2)

[0031] In the dehumidification method using the dehumidifier 1, as preparation for dehumidification, the control unit 40 controls the first temperature control unit 13 to adjust the temperature of the first absorbent liquid in the first regeneration tower 12 so that the temperature of the first absorbent liquid in the first absorption tower 11 is higher. The control unit 40 also controls the second temperature control unit 23 to adjust the temperature of the second absorbent liquid in the second regeneration tower 22 so that the temperature of the second absorbent liquid in the second absorption tower 21 is higher. The control unit 40 also controls the flow control valve 6a to introduce purge gas into the second regeneration tower 22.

[0032] In the dehumidification method using the dehumidifier 1, first, in response to a command from the control unit 40, the flow control valve 5a is controlled to allow hydrogen gas to flow into the first absorption tower 11. When hydrogen gas flows into the first absorption tower 11, it comes into gas-liquid contact with the first absorbent liquid, mainly in the packing material 11a. When hydrogen gas and the first absorbent liquid come into gas-liquid contact in the first absorption tower 11, water vapor and water droplets contained in the hydrogen gas are absorbed by the first absorbent liquid, thus reducing the humidity of the hydrogen gas. The hydrogen gas with reduced humidity (dry hydrogen gas) passes through the hydrogen gas flow path 5 and is supplied to a hydrogen utilization device (not shown) located outside the dehumidifier 1. The first absorbent liquid, which has absorbed the water contained in the hydrogen gas, passes through the first absorbent liquid flow path 14b and flows into the first regeneration tower 12. The first absorbent liquid flowing through the first absorbent liquid channel 14b is heated by the first temperature control unit 13, and therefore flows into the first regeneration tower 12 at a higher temperature than the first absorbent liquid in the first absorption tower 11.

[0033] The first absorbent liquid flowing from the first absorption tower 11 to the first regeneration tower 12 releases water mainly by being held in the packing material 12a, and the first absorbent liquid is regenerated. The regenerated first absorbent liquid flows through the first absorbent liquid channel 14a and into the first absorption tower 11. The first absorbent liquid flowing through the first absorbent liquid channel 14a is cooled by the first temperature control unit 13, and therefore flows into the first absorption tower 11 at a lower temperature than the first absorbent liquid in the first regeneration tower 12. The first absorbent liquid flowing into the first absorption tower 11 absorbs water from the hydrogen gas again through gas-liquid contact with the hydrogen gas, thereby dehumidifying the hydrogen gas.

[0034] In the first regeneration tower 12, water released from the first absorbent liquid spontaneously moves from the first regeneration tower 12 to the second absorption tower 21 via the connecting channel 31. The water flowing from the first regeneration tower 12 to the second absorption tower 21 is absorbed into the second absorbent liquid in the second absorption tower 21, mainly by contact with the packing material 21a. The second absorbent liquid that has absorbed the water flows into the second regeneration tower 22 via the second absorbent liquid channel 24b. The second absorbent liquid flowing through the second absorbent liquid channel 24b is heated by the second temperature control unit 23, and therefore flows into the second regeneration tower 22 at a higher temperature than the second absorbent liquid in the second absorption tower 21.

[0035] In the second regeneration tower 22, purge gas is blown into the temporarily stored second absorbent liquid, causing gas-liquid contact between the second absorbent liquid and the purge gas. When the purge gas and the second absorbent liquid come into gas-liquid contact in the second regeneration tower 22, the water contained in the second absorbent liquid moves into the purge gas, thus reducing the water content of the second absorbent liquid. The second absorbent liquid with reduced water content flows through the second absorbent liquid channel 24a and into the second absorption tower 21. The purge gas, from which the water that was contained in the second absorbent liquid has moved, passes through the purge gas channel 6 and is discharged to the outside of the dehumidifier 1.

[0036] In the dehumidification method using the dehumidifier 1 of this embodiment, the water from the hydrogen gas absorbed in the first absorption tower 11 is discharged from the second regeneration tower 22 by purge gas. In the dehumidifier 1 of this embodiment, as shown in equation (2), the equilibrium pressure Pe22 of the second absorbent liquid in the second regeneration tower 22 is greater than the equilibrium pressure Pe12 of the first absorbent liquid in the first regeneration tower 12. As a result, the amount of water that can be moved per unit mass by gas-liquid contact with the purge gas is greater in the second absorbent liquid of the second regeneration tower 22 than in the first absorbent liquid of the first regeneration tower 12. In other words, the amount of absorbent liquid that can be regenerated by the purge gas is also greater in the second regeneration tower 22 than in the first regeneration tower 12.

[0037] In the dehumidification method using the dehumidifier 1 of this embodiment, the pressure in the connecting channel 31 is controlled. Specifically, the control unit 40 has a threshold value set in advance for the pressure in the connecting channel 31, and when the pressure in the connecting channel 31 exceeds the threshold value, the control unit 40 drives the pump 33 to reduce the pressure in the connecting channel 31. In the dehumidifier 1 of this embodiment, only the first absorbent liquid and the second absorbent liquid enter and exit the first regeneration tower 12 and the second absorption tower 21 respectively, so in principle, no substances other than water and absorbent liquid enter from the outside. However, if, for example, a substance other than water or absorbent liquid enters and remains in the connecting channel 31, the movement of water from the first regeneration tower 12 to the second absorption tower 21 may be hindered. Therefore, the pump 33 is driven using the pressure in the connecting channel 31 detected by the pressure detection unit 34 to maintain the vacuum level in the connecting channel 31. This makes it easier for water to move from the first regeneration tower 12 to the second absorption tower 21.

[0038] Figure 2 is the first diagram illustrating the operation of the dehumidifier 1 of this embodiment. Figure 2 shows the relationship between the moisture content of the absorbent liquid (horizontal axis) and the equilibrium dew point (vertical axis) related to the operation of the dehumidifier 1. Here, the operation of the dehumidifier 1 of this embodiment will be explained using specific numerical values. In Figure 2, the equilibrium dew point of the absorbent liquid in the absorption towers (first absorption tower 11, second absorption tower 21), which are relatively low temperature, is shown by the solid line ELg, and the equilibrium dew point of the absorbent liquid in the regeneration towers (first regeneration tower 12, second regeneration tower 22), which are relatively high temperature, is shown by the solid line EHg.

[0039] In the first absorption tower 11, hydrogen gas with a dew point of 15°C dp (see dashed line CL11 in Figure 2) is dehumidified to a dew point of -45°C dp (see dashed line CL12 in Figure 2) (see dashed line A1 in Figure 2). In this case, as shown in Figure 2, the water content of the first absorbent becomes 0.2 wt%, and the equilibrium dew point of the first absorbent in the first regeneration tower 12 becomes -15°C dp (see dashed line CL13 in Figure 2).

[0040] In the dehumidification method using the dehumidifier 1 of this embodiment, as described above, the water in the first regeneration tower 12 spontaneously moves to the second absorption tower 21. As a result, the water released from the first absorbent liquid in the first regeneration tower 12 is absorbed by the second absorbent liquid with a water content of 3.5 wt% in the second absorption tower 21 (see the dashed line M1 in Figure 2).

[0041] The second absorbent liquid, which has absorbed water in the second absorption tower 21, flows into the second regeneration tower 22. As shown in Figure 2, in the second regeneration tower 22, the equilibrium dew point of the second absorbent liquid with a water content of 3.5 wt% is 25°C (see the dashed line CL14 in Figure 2). As a result, the second absorbent liquid in the second regeneration tower 22 releases the absorbed water more easily than the first absorbent liquid in the first regeneration tower 12 (equilibrium dew point: -15°C dp) (see the dashed line R1 in Figure 2). Therefore, a relatively large amount of water can be released to the outside of the dehumidifier 1 along with the purge gas.

[0042] Figure 3 is a second diagram illustrating the operation of the dehumidifier of this embodiment. Figure 3 shows several numerical values ​​related to the operation described in Figure 2. As shown in Figure 3, in the dehumidifier 1, the flow rate of hydrogen gas supplied to the first absorption tower 11 is set to 10 Nm³ 3 If set to / h, the required flow rate of purge gas in the second regeneration tower 22 is 5.6 Nm³. 3 It becomes / h.

[0043] Figure 4 is a schematic diagram showing the general configuration of a comparative example dehumidifier. Here, we calculate the ratio of the required purge gas flow rate to the target gas flow rate in the comparative example dehumidifier, compared to the ratio of the required purge gas flow rate to the target gas flow rate in the dehumidifier 1 of this embodiment, as explained in Figures 2 and 3.

[0044] The comparative example dehumidifier 9A is a so-called single-stage dehumidifier comprising an absorption tower 91, a regeneration tower 92, and a temperature control unit 93. In the comparative example dehumidifier 9A, an ionic liquid is used as the absorbent liquid, similar to the dehumidifier 1 of this embodiment.

[0045] The absorption tower 91 is filled with packing material 91a such as metal or ceramic. Examples of packing material 91a include Raschig rings, Dickson packing, and woven mesh. In addition to the absorption liquid channel 94a through which the absorption liquid from the regeneration tower 92 (described later) flows, and the absorption liquid channel 94b through which the absorption liquid from the absorption tower 91 flows, the absorption tower 91 is also connected to a hydrogen gas channel 5.

[0046] The regeneration tower 92 is filled with packing material 92a such as metal or ceramic. Examples of packing material 92a include Raschig rings, Dixon packing, and woven mesh. The regeneration tower 92 is connected to an absorption liquid channel 94b and an absorption liquid channel 94a. The absorption liquid channel 94a is equipped with a liquid transfer pump 94c that pressurizes and pumps the absorption liquid so that the absorption liquid circulates between the absorption tower 91 and the regeneration tower 92.

[0047] The temperature control unit 93 comprises a cooler 93a, a heater 93b, and a heat exchanger 93c. Similar to the first temperature control unit 13 and the second temperature control unit 23 in this embodiment, the temperature control unit 93 cools the absorbent liquid flowing through the absorbent liquid channel 94a and heats the absorbent liquid flowing through the absorbent liquid channel 94b. As a result, the temperature of the absorbent liquid in the regeneration tower 92 is higher than the temperature of the absorbent liquid in the absorption tower 91.

[0048] Figure 5 is a diagram illustrating the operation of the comparative dehumidifier 9A. Figure 5 corresponds to Figure 2 in the dehumidifier 1 of this embodiment. In the dehumidification method using the comparative dehumidifier 9A, hydrogen gas with a dew point of 15°C dp (see dashed line CL01 in Figure 5) is dehumidified in the absorption tower 91 using an absorbent with a water content of 0.2 wt% to a dew point of -45°C dp (see dashed line CL02 in Figure 5) (see dashed line A0 in Figure 5). In this case, the equilibrium dew point of the absorbent in the regeneration tower 92 is the same as the equilibrium dew point of the first absorbent in the first regeneration tower 12 of the dehumidifier 1, which is -15°C dp (see dashed line CL03 in Figure 5). In other words, the comparative dehumidifier 9A is less likely to release water absorbed in the absorbent than the dehumidifier 1 of this embodiment shown in Figure 2 (see dashed line R0 in Figure 5).

[0049] Next, the performance of the dehumidifying device 9A of the comparative example will be described using numerical values. The conditions described in FIG. 5 are as follows. · Hydrogen gas Flow rate: 10 Nm 3 / h Inlet dew point of the absorption tower: 15 °C dp Outlet dew point of the absorption tower: -45 °C dp · Purge gas Inlet dew point of the regeneration tower: -45 °C dp Outlet dew point of the regeneration tower: -15 °C dp From the absolute humidity of the hydrogen gas and the purge gas under such conditions, the flow rate of the purge gas required in the regeneration tower 92 was calculated. · Hydrogen gas Absolute humidity at the inlet of the absorption tower: 12.5 g / m 3 Absolute humidity at the outlet of the absorption tower: 0.082 g / m 3 (Dehumidification amount of the absorption tower: 124.2 g / h) · Purge gas Absolute humidity at the inlet of the regeneration tower: 0.082 g / m 3 Absolute humidity at the outlet of the regeneration tower: 1.4 g / m 3 Required purge gas flow rate: 94 Nm 3 / h

[0050] Thus, in the dehumidifying device 9A of the comparative example, in order to regenerate the absorption liquid that has dehumidified 10 Nm 3 / h of hydrogen gas, it was found that 94 Nm 3 / h of purge gas is required. Therefore, it was found that the dehumidifying device 1 of the present embodiment, which requires 5.6 Nm 3 / h of purge gas for 10 Nm 3 / h of hydrogen gas, can reduce the amount of purge gas required compared to the comparative example.

[0051] As described above, the dehumidifier 1 of this embodiment is configured such that the combination of absorption towers and regeneration towers is multi-stage. In the preceding first regeneration tower 12, water released from the first absorbent is absorbed into the second absorbent in the subsequent second absorption tower 21. In such a multi-stage dehumidifier, the equilibrium dew point of the second absorbent in the subsequent second regeneration tower 22 is higher than the equilibrium dew point of the first absorbent in the preceding first regeneration tower 12. As a result, the amount of water released from the second absorbent per unit time in the second regeneration tower 22 is greater than the amount of water released from the first absorbent per unit time in the first regeneration tower 12. Therefore, the water removed from the target gas in the preceding first absorption tower 11 can be efficiently released to the outside of the dehumidifier 1, thereby improving the dehumidification efficiency of the dehumidifier 1.

[0052] Furthermore, according to the dehumidifier 1 of this embodiment, water released from the first absorbent liquid in the first regeneration tower 12 moves to the second absorption tower 21 through the connecting channel 31. When the pressure in the connecting channel 31 exceeds a preset threshold, the control unit 40 drives the pump 33 to reduce the pressure in the connecting channel 31. This reduces the amount of foreign matter, such as gas molecules other than water, that may hinder the movement of water in the connecting channel 31, making it easier for water to move from the first regeneration tower 12 to the second absorption tower 21. Therefore, the dehumidification efficiency of the dehumidifier 1 can be further improved.

[0053] Furthermore, according to the dehumidifier 1 of this embodiment, the dehumidifier 1 absorbs the water contained in the hydrogen gas, which is generated by the water electrolysis device and contains hydrogen and water, using the first absorbent liquid. This makes it possible to effectively utilize the hydrogen generated by the water electrolysis device.

[0054] Furthermore, according to the dehumidifier 1 of this embodiment, since the first absorbent liquid and the second absorbent liquid are ionic liquids with almost no vapor pressure, mixing of the first absorbent liquid and the second absorbent liquid can be suppressed as water moves from the first regeneration tower 12 to the second absorption tower 21. Therefore, the dehumidification efficiency of the dehumidifier 1 can be maintained.

[0055] Furthermore, according to the dehumidification method of this embodiment, the equilibrium dew point of the second absorbent liquid in the second regeneration tower 22 is set higher than the equilibrium dew point of the first absorbent liquid in the first regeneration tower 12, allowing water to be efficiently released to the outside of the dehumidifier 1. Therefore, the dehumidification efficiency of the dehumidifier 1 can be improved.

[0056] Furthermore, according to the computer program of this embodiment, the control unit 40 raises the equilibrium dew point of the second absorbent liquid in the second regeneration tower 22 to a higher level than the equilibrium dew point of the first absorbent liquid in the first regeneration tower 12, thereby enabling efficient water discharge to the outside of the dehumidifier 1. Consequently, the dehumidification efficiency of the dehumidifier 1 can be improved.

[0057] <Second Embodiment> Figure 6 is a schematic diagram showing the general configuration of the dehumidifier of the second embodiment. The dehumidifier of the second embodiment differs from the dehumidifier of the first embodiment (Figure 1) in that it supplies a portion of the dry hydrogen gas, from which water has been absorbed in the first absorption tower, as a purge gas to the second regeneration tower.

[0058] The dehumidifier 2 of this embodiment includes a first absorption tower 11, a first regeneration tower 12, a first temperature control unit 13, a second absorption tower 21, a second regeneration tower 22, a second temperature control unit 23, a control unit 40, and a purge gas supply unit 50. The purge gas supply unit 50 is provided to connect the first absorption tower 11 and the second regeneration tower 22.

[0059] The purge gas supply unit 50 includes purge gas flow paths 51a and 51b, a flow control valve 52, and a cooler 53. The purge gas flow path 51a is connected to the first absorption tower 11 and the second regeneration tower 22, and is configured so that a portion of the gas in the first absorption tower 11 flows toward the second regeneration tower 22. The gas flowing through the purge gas flow path 51a is hydrogen gas with relatively low humidity, from which water has been removed in the first absorption tower 11. The purge gas flow path 51b is connected to the second regeneration tower 22 and the first absorption tower 11, and is configured so that the gas in the second regeneration tower 22 flows toward the first absorption tower 11. The gas flowing through the purge gas flow path 51b is hydrogen gas with relatively high humidity, containing water released from the second absorbent liquid in the second regeneration tower 22.

[0060] The flow control valve 52 is connected to the purge gas flow path 51a. The flow control valve 52 controls the flow rate of relatively low-humidity hydrogen gas flowing into the second regeneration tower 22 in response to commands from the electrically connected control unit 40.

[0061] The cooler 53 is connected to the purge gas flow path 51b. The cooler 53 cools the relatively humid hydrogen gas flowing through the purge gas flow path 51b and removes water from the hydrogen gas by condensing at least a portion of the water vapor contained in the hydrogen gas. In this embodiment, the cooling temperature of the hydrogen gas in the cooler 53 can be arbitrarily set. The hydrogen gas cooled by the cooler 53 returns to the first absorption tower 11.

[0062] Figure 7 is a diagram illustrating the operation of the dehumidifier 2 of this embodiment. Figure 7 shows the relationship between the moisture content of the absorbent liquid (horizontal axis) and the equilibrium dew point (vertical axis) related to the operation of the dehumidifier 2. Here, the outlet dew point of hydrogen gas in the first absorption tower 11 of the dehumidifier 2 of this embodiment is calculated using specific numerical values.

[0063] In the dehumidifier 2 of this embodiment, the cooling temperature of the cooler 53 is set to, for example, 20°C (see the dashed line CL21 in Figure 7). In this case, the outlet dew point of hydrogen gas in the second regeneration tower 22 will be at least 20°Cdp, so the equilibrium dew point of the second absorbent liquid in the second absorption tower 21 will be -20°Cdp (see the dashed line CL22 in Figure 7). Consequently, the equilibrium dew point of the first absorbent liquid in the first regeneration tower 12 will also be -20°Cdp, so the outlet dew point of hydrogen gas in the first absorption tower 11 will be -55°Cdp, as shown in Figure 7 (see the dashed line CL23 in Figure 7).

[0064] Figure 8 is a schematic diagram showing the general configuration of a comparative example dehumidifier. The comparative example dehumidifier 9B shown in Figure 8 includes a purge gas supply unit 95 in addition to the comparative example dehumidifier 9A described in the first embodiment. The purge gas supply unit 95 includes purge gas passages 951a and 951b, a flow control valve 952, and a cooler 953. The purge gas passage 951a is connected to the absorption tower 91 and the regeneration tower 92, and supplies a portion of the hydrogen gas from which water has been absorbed in the absorption tower 91 to the regeneration tower 92 as purge gas. The purge gas passage 951b is connected to the regeneration tower 92 and the absorption tower 91, and returns the hydrogen gas from which water has been absorbed in the regeneration tower 92 to the absorption tower 91. The purge gas passage 951b is provided with a flow control valve 952 that controls the flow rate of purge gas in the purge gas passage 951b, and a cooler 953 that cools the purge gas flowing through the purge gas passage 951b. Dehumidifier 9B is a so-called single-stage dehumidifier. In the comparative example dehumidifier 9B, an ionic liquid is used as the absorbent liquid, similar to dehumidifier 2 in this embodiment.

[0065] Figure 9 is a diagram illustrating the operation of the comparative example dehumidifier. Figure 9 corresponds to Figure 7 in the dehumidifier 2 of this embodiment. As shown in Figure 9, in the comparative example dehumidifier 9B, the cooling temperature of the cooler 953 is set to 20°C, similar to the operation of the dehumidifier 2 of this embodiment described in Figure 7 (see the dashed line CL04 in Figure 9). As a result, the outlet dew point of hydrogen gas in the absorption tower 91 becomes -20°Cdp (see the dashed line CL05 in Figure 9). In other words, in the comparative example dehumidifier 9B, the absorption tower 91 can only dehumidify hydrogen gas to a dew point of -20°Cdp or higher. Therefore, the dehumidifier 2 of this embodiment can dehumidify hydrogen gas to a lower humidity than the comparative example dehumidifier 9B. In other words, the dehumidifier 2 of this embodiment has a wider range of dehumidification capabilities than the comparative example dehumidifier 9B.

[0066] As described above, with the dehumidifier 2 of this embodiment, the equilibrium dew point of the second absorbent in the second regeneration tower 22 is higher than the equilibrium dew point of the first absorbent in the first regeneration tower 12. Therefore, the amount of water released from the second absorbent per unit time in the second regeneration tower 22 is greater than the amount of water released from the first absorbent per unit time in the first regeneration tower 12. Consequently, the water removed from the target gas in the first absorption tower 11 can be efficiently released to the outside of the dehumidifier 2, thereby improving the dehumidification efficiency of the dehumidifier 2.

[0067] Furthermore, according to the dehumidifier 2 of this embodiment, the second regeneration tower 22 uses hydrogen gas from which water has been absorbed in the first absorbent liquid in the first absorption tower 11, i.e., relatively dry hydrogen gas, to release water from the second absorbent liquid, thus enabling efficient water release from the second absorbent liquid. The purge gas from which water has been released from the second absorbent liquid is cooled by a cooler 53 connected to the purge gas flow path, removing at least a portion of the absorbed water, before returning to the first absorption tower 11. In this way, the purge gas for releasing water from the second absorbent liquid can be circulated within the dehumidifier 2, reducing or eliminating the need for purge gas taken in from the outside. This further improves the dehumidification efficiency of the dehumidifier 2.

[0068] Furthermore, according to the dehumidifier 2 of this embodiment, the hydrogen gas that returns from the second regeneration tower 22 to the first absorption tower 11, after releasing water from the second absorbent liquid, is cooled by the cooler 53. Therefore, the equilibrium dew point of the second absorbent liquid in the second absorption tower 21 is set according to the cooling temperature of the cooler 53. Since the equilibrium dew point of the first absorbent liquid in the first regeneration tower 12 is approximately the same as the equilibrium dew point of the second absorbent liquid in the second absorption tower 21, the equilibrium dew point of the first absorbent liquid in the first absorption tower 11 is lower than the equilibrium dew point of the second absorbent liquid in the second absorption tower 21. As a result, the humidity of the hydrogen gas flowing out of the first absorption tower 11 can be made relatively low, and the hydrogen gas can be dehumidified to an even lower humidity. Therefore, the dehumidification efficiency of the dehumidifier 2 can be further improved.

[0069] <Third Embodiment> Figure 10 is a schematic diagram showing the general configuration of the dehumidifier of the third embodiment. The dehumidifier of the third embodiment differs from the dehumidifier of the second embodiment (Figure 6) in that it circulates gas between the first regeneration tower and the second absorption tower.

[0070] The dehumidifier 3 of this embodiment includes a first absorption tower 11, a first regeneration tower 12, a first temperature control unit 13, a second absorption tower 21, a second regeneration tower 22, a second temperature control unit 23, a control unit 40, a purge gas supply unit 50, and a gas circulation unit 60. The gas circulation unit 60 is provided to connect to the first regeneration tower 12 and the second absorption tower 21.

[0071] The gas circulation section 60 comprises circulating gas passages 61a and 61b, and compressors 62 and 63. The circulating gas passage 61a is connected to the first regeneration tower 12 and the second absorption tower 21, and is configured so that the gas in the first regeneration tower 12 flows toward the second absorption tower 21. The circulating gas passage 61a is equipped with a compressor 62 that pressurizes the gas in the circulating gas passage 61a so that the gas in the first regeneration tower 12 flows toward the second absorption tower 21. The circulating gas passage 61b is connected to the first regeneration tower 12 and the second absorption tower 21, and is configured so that the gas in the second absorption tower 21 flows toward the first regeneration tower 12. The circulating gas passage 61b is equipped with a compressor 63 that pressurizes the gas in the circulating gas passage 61b so that the gas in the second absorption tower 21 flows toward the first regeneration tower 12. In this embodiment, the gas flowing through the circulating gas channels 61a and 61b between the first regeneration tower 12 and the second absorption tower 21 (circulating gas) is the same type of gas as the hydrogen gas from which water is absorbed into the first absorbent liquid in the first absorption tower 11. This makes it possible to suppress a decrease in the purity of the hydrogen gas flowing through the hydrogen gas channel 5 even if the gas from the gas circulation section 60 leaks into the first absorption tower 11.

[0072] In the dehumidifier 3 of this embodiment, the amount of water released from the first absorbent liquid increases when circulating gas flows into the first regeneration tower 12. Since the circulating gas circulates between the first regeneration tower 12 and the second absorption tower 21, the water released from the first absorbent liquid in the first regeneration tower 12 is forcibly moved to the second absorption tower 21 along with the circulating gas. As a result, the water moves faster than if it were to move spontaneously due to the pressure difference between the first regeneration tower 12 and the second absorption tower 21. Therefore, the dehumidification rate in the dehumidifier 3 can be improved. In addition, in the dehumidifier 3 of this embodiment, as with the dehumidifier 1 of the first embodiment, the equilibrium pressure Pe12 of the first absorbent liquid in the first regeneration tower 12 is smaller than the equilibrium pressure Pe22 of the second absorbent liquid in the second regeneration tower 22.

[0073] As described above, with the dehumidifier 3 of this embodiment, the equilibrium dew point of the second absorbent in the second regeneration tower 22 is higher than the equilibrium dew point of the first absorbent in the first regeneration tower 12. Therefore, the amount of water released from the second absorbent per unit time in the second regeneration tower 22 is greater than the amount of water released from the first absorbent per unit time in the first regeneration tower 12. Consequently, the water removed from the target gas in the first absorption tower 11 can be efficiently released to the outside of the dehumidifier 3, thereby improving the dehumidification efficiency of the dehumidifier 3.

[0074] Furthermore, according to the dehumidifier 3 of this embodiment, the circulating gas that circulates between the first regeneration tower 12 and the second absorption tower 21 comes into gas-liquid contact with the first absorbent liquid, thereby promoting the release of water from the first absorbent liquid in the first regeneration tower 12. The circulating gas containing water released from the first absorbent liquid in the first regeneration tower 12 is forcibly moved to the second absorption tower 21 by the compressor 62, where the water it contains is absorbed by the second absorbent liquid. This allows the water absorbed by the first absorbent liquid from the hydrogen gas in the first absorption tower 11 to be efficiently sent to the second absorption tower 21. Therefore, the dehumidification efficiency of the dehumidifier 3 can be further improved.

[0075] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0076] [Example 1] In the above embodiment, although the first absorbent and the second absorbent are the same type of ionic liquid, the water content of the second absorbent is assumed to be higher than that of the first absorbent. The relationship between the first absorbent and the second absorbent is not limited to this. When the first absorbent and the second absorbent are the same type of ionic liquid, the temperature of the second absorbent in the second regeneration tower may be higher than the temperature of the first absorbent in the first regeneration tower. Also, in the above embodiment, since the combination of the first absorption tower 11 and the first regeneration tower 12 and the combination of the second absorption tower 21 and the second regeneration tower 22 are independent, it is also possible to use different types of ionic liquids for the first absorbent and the second absorbent. When the first absorbent and the second absorbent are different types of ionic liquids, for example, it is desirable that the second absorbent has a lower water absorption capacity in the absorption tower than the first absorbent, but a higher regeneration capacity in the regeneration tower. Furthermore, when the first absorbent and the second absorbent are different types of ionic liquids, the second absorbent may be an absorbent with a relatively high heat resistance temperature. In this case, the temperature of the second absorbent in the second regeneration tower can be set even higher than the temperature of the first absorbent in the first regeneration tower, so that the equilibrium dew point in the second regeneration tower can be made even higher than the equilibrium dew point in the first regeneration tower.

[0077] Furthermore, as a method to make the equilibrium dew point in the second regeneration tower greater than that in the first regeneration tower, for example, a method using a combination of a solid adsorbent and an absorbent liquid may be used, or a method that considers the reactivity between the target gas to be dehumidified and the absorbent liquid. In the method that considers the reactivity between the target gas to be dehumidified and the absorbent liquid, a liquid with relatively low reactivity with the target gas is used as the first absorbent liquid, and a liquid with relatively high reactivity with the target gas is used as the second absorbent liquid, thereby allowing water vapor to be moved from the first regeneration tower to the second absorption tower. This makes it possible to make the equilibrium dew point in the second regeneration tower greater than that in the first regeneration tower.

[0078] [Differentiation 2] In the above-described embodiment, the dehumidifier is a two-stage type dehumidifier in which a combination of a first absorption tower 11 and a first regeneration tower 12 and a combination of a second absorption tower 21 and a second regeneration tower 22 are connected in stages. A multi-stage dehumidifier with three or more stages may also be used. As the number of stages increases, the equilibrium dew point of the absorbent liquid in the final regeneration tower increases, and therefore the amount of water released from the absorbent liquid per unit time increases.

[0079] [Difference 3] In the embodiments described above, the absorption tower or regeneration tower was assumed to be filled with packing material. The configuration of the absorption tower and regeneration tower is not limited to this. In the absorption tower, it is sufficient that water is absorbed from the absorbent liquid by contact between the water-containing gas and the absorbent liquid, and in the regeneration tower, it is sufficient that water is released from the absorbent liquid.

[0080] [Differentiation Example 4] In the above embodiment, the target gas to be dehumidified by the dehumidifier was assumed to be a mixed gas containing hydrogen and water, produced by a water electrolysis device. However, the target gas to be dehumidified by the dehumidifier is not limited to this; any mixed gas containing water is acceptable.

[0081] [Difference 5] In the above-described embodiment, an ionic liquid was used as the absorbent liquid to absorb water contained in the mixed gas. However, in the dehumidifier of the above-described embodiment, the absorbent liquid that absorbs water or water vapor is not limited to an ionic liquid. It may also be ethylene glycols, as described above.

[0082] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0083] <Application Example 1> A dehumidifier, A first absorption tower absorbs water contained in the target gas into a first absorption liquid, A first regeneration tower connected to the first absorption tower, which releases water from the first absorption liquid flowing in from the first absorption tower, and a first regeneration tower which returns the first absorption liquid from which water has been released back to the first absorption tower, A second absorption tower is connected to the first regeneration tower and absorbs the water released from the first absorption liquid in the first regeneration tower into the second absorption liquid, A second regeneration tower connected to the second absorption tower, which releases water from the second absorption liquid flowing in from the second absorption tower, and a second regeneration tower that returns the second absorption liquid from which water has been released back to the second absorption tower, Equipped with, The equilibrium dew point of the second absorbent in the second regeneration tower is greater than the equilibrium dew point of the first absorbent in the first regeneration tower. Dehumidifier. <Application Example 2> The dehumidifier described in Application Example 1 further, A connecting channel is provided, which is connected to the first regeneration tower and the second absorption tower, and through which water released from the first absorption liquid in the first regeneration tower flows. A pressure detection unit for detecting the pressure in the connecting channel, A pump that reduces the pressure in the aforementioned connecting channel, The system comprises a control unit that controls the pump using the pressure in the connecting channel detected by the pressure detection unit, The control unit drives the pump to reduce the pressure in the connecting channel when the pressure in the connecting channel exceeds a preset threshold. Dehumidifier. <Application Example 3> The dehumidifying device described in Application Example 1 or Application Example 2 further includes: A circulating gas flow path is connected to the first regeneration tower and the second absorption tower, and through which circulating gas flows circulating between the first regeneration tower and the second absorption tower, The system includes a compressor connected to the aforementioned circulating gas flow path, The first regeneration tower releases water from the first absorbent by incorporating the water from the first absorbent into the circulating gas. The second absorption tower absorbs the water contained in the circulating gas into the second absorbent liquid. Dehumidifier. <Application Example 4> The dehumidifying device described in any one of the examples from Application Example 1 to Application Example 3 further, The first absorption tower is equipped with a purge gas supply unit that supplies the target gas from which at least a portion of the contained water has been removed to the second regeneration tower and brings it into contact with the second absorbent liquid, thereby releasing water from the second absorbent liquid as a purge gas. The aforementioned purge gas supply unit is, A purge gas flow path is connected to the second regeneration tower and the first absorption tower, and returns the purge gas, which has released water from the second absorption liquid in the second regeneration tower, back to the first absorption tower. The system includes a cooler connected to the purge gas flow path for cooling the purge gas flowing through the purge gas flow path, Dehumidifier. <Application Example 5> A dehumidifying device described in any one of the examples from Application Example 1 to Application Example 4, The aforementioned target gas is a mixed gas containing hydrogen and water, produced by a water electrolysis device. Dehumidifier. <Application Example 6> A dehumidifying device described in any one of Application Examples 1 to 5, At least one of the first and second absorption solutions is an ionic liquid. Dehumidifier. <Application Example 7> A dehumidification method using a dehumidifying device, In the first absorption tower, the first absorption step involves absorbing water contained in the target gas into the first absorption liquid, A first regeneration step of releasing water from the first absorbent liquid that has flowed from the first absorption tower into the first regeneration tower, the first regeneration step of returning the first absorbent liquid from which water has been released back to the first absorption tower, A second absorption step in which water released from the first absorbent liquid in the first regeneration tower is absorbed into the second absorbent liquid in the second absorption tower, A second regeneration step in which water is released from the second absorbent liquid that flows from the second absorption tower to the second regeneration tower, and a second regeneration step in which the water-released second absorbent liquid is returned to the second absorption tower, Equipped with, The equilibrium dew point of the second absorbent in the second regeneration tower is greater than the equilibrium dew point of the first absorbent in the first regeneration tower. Dehumidification method. <Application Example 8> A computer program that causes a computer to perform dehumidification of a target gas using a dehumidifying device, In the first absorption tower, there is a first absorption function that absorbs water contained in the target gas into the first absorption liquid, A first regeneration function that releases water from the first absorbent liquid that flows from the first absorption tower to the first regeneration tower, and a first regeneration function that returns the first absorbent liquid from which water has been released back to the first absorption tower, The first regeneration tower has a second absorption function which involves absorbing the water released from the first absorption liquid into the second absorption liquid in the second absorption tower, The computer is instructed to perform a second regeneration function which releases water from the second absorbent liquid that flows from the second absorption tower into the second regeneration tower, and a second regeneration function which returns the water-free second absorbent liquid back to the second absorption tower. The equilibrium dew point of the second absorbent in the second regeneration tower is greater than the equilibrium dew point of the first absorbent in the first regeneration tower. Computer program. [Explanation of Symbols]

[0084] 1,2,3…Dehumidifier 11…First absorption tower 12…1st regeneration tower 21…Second absorption tower 22…Second regeneration tower 31…Connection channel 33... Pump 34... Pressure detection unit 40... Control Unit 50... Purge gas supply unit 51a, 52a... Purge gas flow path 53... Purge gas supply unit 61a, 61b… Circulating gas flow path 62, 63… Compressor

Claims

1. A dehumidifier, A first absorption tower absorbs water contained in the target gas into a first absorption liquid, A first regeneration tower connected to the first absorption tower, which releases water from the first absorption liquid flowing in from the first absorption tower, and a first regeneration tower that returns the first absorption liquid from which water has been released back to the first absorption tower, A second absorption tower is connected to the first regeneration tower and absorbs the water released from the first absorption liquid in the first regeneration tower into the second absorption liquid, A second regeneration tower connected to the second absorption tower, which releases water from the second absorption liquid flowing in from the second absorption tower, and a second regeneration tower which returns the second absorption liquid from which water has been released back to the second absorption tower, Equipped with, The equilibrium dew point of the second absorbent in the second regeneration tower is greater than the equilibrium dew point of the first absorbent in the first regeneration tower. Dehumidifier.

2. The dehumidifying device according to claim 1 further, A connecting channel is provided, which is connected to the first regeneration tower and the second absorption tower, and through which water released from the first absorption liquid in the first regeneration tower flows. A pressure detection unit for detecting the pressure in the connecting channel, A pump that reduces the pressure in the aforementioned connecting channel, The system comprises a control unit that controls the pump using the pressure in the connecting channel detected by the pressure detection unit, The control unit drives the pump to reduce the pressure in the connecting channel when the pressure in the connecting channel exceeds a preset threshold. Dehumidifier.

3. The dehumidifying device according to claim 1 further, A circulating gas flow path is connected to the first regeneration tower and the second absorption tower, and through which circulating gas flows circulating between the first regeneration tower and the second absorption tower, The system includes a compressor connected to the aforementioned circulating gas flow path, The first regeneration tower releases water from the first absorbent by incorporating the water from the first absorbent into the circulating gas. The second absorption tower absorbs the water contained in the circulating gas into the second absorbent liquid. Dehumidifier.

4. The dehumidifying device according to any one of claims 1 to 3 further, The first absorption tower is equipped with a purge gas supply unit that supplies the target gas from which at least a portion of the contained water has been removed to the second regeneration tower and brings it into contact with the second absorbent liquid, thereby releasing water from the second absorbent liquid as a purge gas. The aforementioned purge gas supply unit is, A purge gas flow path is connected to the second regeneration tower and the first absorption tower, and returns the purge gas, which has released water from the second absorption liquid in the second regeneration tower, back to the first absorption tower. The system includes a cooler connected to the purge gas flow path for cooling the purge gas flowing through the purge gas flow path, Dehumidifier.

5. A dehumidifying device according to any one of claims 1 to 3, The aforementioned target gas is a mixed gas containing hydrogen and water, produced by a water electrolysis device. Dehumidifier.

6. A dehumidifying device according to any one of claims 1 to 3, At least one of the first and second absorption solutions is an ionic liquid. Dehumidifier.

7. A dehumidification method using a dehumidifying device, In the first absorption tower, a first absorption step is performed in which water contained in the target gas is absorbed into the first absorbent liquid, A first regeneration step of releasing water from the first absorbent liquid that has flowed from the first absorption tower into the first regeneration tower, the first regeneration step of returning the first absorbent liquid from which water has been released back to the first absorption tower, A second absorption step in which water released from the first absorbent liquid in the first regeneration tower is absorbed into the second absorbent liquid in the second absorption tower, A second regeneration step in which water is released from the second absorbent liquid that flows from the second absorption tower to the second regeneration tower, the second regeneration step in which the water-released second absorbent liquid is returned to the second absorption tower, Equipped with, The equilibrium dew point of the second absorbent in the second regeneration tower is greater than the equilibrium dew point of the first absorbent in the first regeneration tower. Dehumidification method.

8. A computer program that causes a computer to perform dehumidification of a target gas using a dehumidifying device, In the first absorption tower, there is a first absorption function that absorbs water contained in the target gas into the first absorption liquid, A first regeneration function that releases water from the first absorbent liquid that flows from the first absorption tower to the first regeneration tower, and a first regeneration function that returns the first absorbent liquid from which water has been released back to the first absorption tower, The first regeneration tower has a second absorption function which involves absorbing the water released from the first absorption liquid into the second absorption liquid in the second absorption tower, The computer is instructed to perform a second regeneration function which releases water from the second absorbent liquid that flows from the second absorption tower into the second regeneration tower, and a second regeneration function which returns the water-free second absorbent liquid back to the second absorption tower. The equilibrium dew point of the second absorbent in the second regeneration tower is greater than the equilibrium dew point of the first absorbent in the first regeneration tower. Computer program.

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