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 that releases water from the first absorbent liquid that has absorbed water in the first absorption tower and returns the first absorbent liquid that has released water back to the first absorption tower, a cooling unit that generates cooling by generating water vapor and cools the first absorbent liquid that returns from the first regeneration tower to the first absorption tower, and a second absorption tower connected to the cooling unit that absorbs the water vapor generated in the cooling unit into a second absorbent liquid.

Description

Technical Field

[0001] The present invention relates to a dehumidifying device, a dehumidifying method, and a computer program. It relates thereto.

Background Art

[0002] Conventionally, a dehumidifying device for adjusting the humidity of a gas has been known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even with the prior art such as Patent Document 1, there is still room for improvement in the technology for improving the dehumidifying efficiency in a dehumidifying device.

[0005] The present invention has been made to solve the above-described problems, and an object thereof is to provide a technology for improving the dehumidifying efficiency in a dehumidifying device.

Means for Solving the Problems

[0006] The present invention has been made to solve at least a part of the above-described 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 that releases water from the first absorbent liquid that has absorbed water in the first absorption tower, and returns the first absorbent liquid that has released water back to the first absorption tower; a cooling unit that generates cooling by generating water vapor and cools the first absorbent liquid that returns from the first regeneration tower to the first absorption tower; and a second absorption tower connected to the cooling unit that absorbs the water vapor generated in the cooling unit into a second absorbent liquid.

[0008] In this configuration, the cooling section uses the heat of vaporization generated when water vapor is produced as cooling energy to cool the first absorbent liquid that the first regeneration tower returns to the first absorption tower. The water vapor generated in the cooling section is absorbed by the second absorbent liquid in the second absorption tower connected to the cooling section. As a result, the temperature of the cooling energy generated in the cooling section can be kept relatively low, and the equilibrium dew point of the first absorbent liquid in the first absorption tower can be kept relatively low. Therefore, the dehumidification efficiency in the first absorption tower can be improved.

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

[0010] (3) In the dehumidifier of the above form, the second absorption tower is supplied with the first absorbent liquid that has absorbed water in the first absorption tower, and the second absorbent liquid may be the first absorbent liquid that has absorbed water in the first absorption tower. With this configuration, the second absorption tower uses the first absorbent liquid that has absorbed water in the first absorption tower to absorb water vapor generated inside the cooling section. As a result, the first absorbent liquid flowing into the first absorption tower can be cooled by the first absorbent liquid that absorbs water contained in the target gas, so that only one type of absorbent liquid is required for dehumidification. Therefore, the configuration of the dehumidifier becomes relatively simple, and the cost required for dehumidification can be reduced.

[0011] (4) In the dehumidifier of the above form, 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 in the first absorption tower to the first regeneration tower and brings it into contact with the first absorbent liquid, thereby releasing water from the first absorbent liquid as a purge gas, the purge gas supply unit may be connected to the first regeneration tower and the first absorption tower and have a purge gas flow path that returns the purge gas, which has released water from the first absorbent liquid in the first regeneration tower, to the first absorption tower, and a purge gas 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 first regeneration tower, the target gas from which at least a portion of the contained water has been removed in the first absorption tower, i.e., a relatively dry gas, is used as a purge gas to release water from the first absorbent liquid, so that water can be released from the first absorbent liquid efficiently. The purge gas, which has released water from the first absorption liquid, is cooled by a purge gas cooler connected to the purge gas flow path. After at least some of the absorbed water is removed, the purge gas returns to the first absorption tower. In this way, the purge gas used to release water from the first absorption 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) The dehumidification device of the above form further includes a second regeneration tower that releases water from the second absorbent liquid that has absorbed water vapor in the second absorption tower, and returns the second absorbent liquid from which water has been released back to the second absorption tower, and the second absorption tower may allow the second absorbent liquid returning from the second regeneration tower to absorb the water vapor generated in the cooling section. With this configuration, the dehumidification device includes a combination of a first absorption tower and a first regeneration tower through which a first absorbent liquid that absorbs water contained in the target gas circulates, and a combination of a second absorption tower and a second regeneration tower through which a second absorbent liquid that absorbs water vapor generated in the cooling section circulates. As a result, water vapor generated in the cooling section can be absorbed stably, and dehumidification can be stably performed in the first absorption tower, which is supplied with a sufficiently cooled first absorbent liquid.

[0013] (6) 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.

[0014] (7) In the dehumidifier of the above form, the second absorbent liquid may be an ionic liquid. With this configuration, since the second absorbent liquid is an ionic liquid with almost no vapor pressure, its movement to the cooling section is suppressed. Therefore, mixing of the absorbent liquid and water in the cooling section can be suppressed, and the dehumidification efficiency of the dehumidifier can be maintained.

[0015] (8) Another embodiment of the present invention provides a dehumidification method using a dehumidification device. 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 regeneration step in which the first absorbent liquid that absorbed water in the first absorption step releases water, and the regeneration step in which the first absorbent liquid that released water is returned to the first absorption tower in a regeneration tower; a cooling step in which cold energy is generated by generating water vapor and the first absorbent liquid that is returned from the regeneration tower to the first absorption tower is cooled; and a second absorption step in which the water vapor generated in the cooling step is absorbed into a second absorbent liquid. With this configuration, in the cooling step, the heat of vaporization when water vapor is generated is used as cold energy to cool the first absorbent liquid that the first regeneration tower returns to the first absorption tower. Since the water vapor generated in the cooling step is absorbed into a second absorbent liquid in a second absorption tower, the temperature of the generated cold energy can be made relatively low. Therefore, the equilibrium dew point of the first absorbent liquid in the first absorption step can be made relatively small, and thus the dehumidification efficiency can be improved.

[0016] (9) 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 dehumidifier. 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 regeneration function which causes water to be released from the first absorbent liquid that has absorbed water by the first absorption function, and which returns the first absorbent liquid that has released water to the first absorption tower in a regeneration tower; a cooling function which generates cold energy by generating water vapor and cools the first absorbent liquid that returns from the regeneration tower to the first absorption tower; and a second absorption function which causes the water vapor generated by the cooling function to be absorbed into a second absorbent liquid. With this configuration, the cooling function cools the first absorbent liquid that the first regeneration tower returns to the first absorption tower using the heat of vaporization when water vapor is generated as cold energy. Since the water vapor generated by the cooling function is absorbed into a second absorbent liquid in a second absorption tower, the temperature of the cold energy generated can be made relatively low. Therefore, when the first absorption function absorbs water contained in the target gas into the first absorbent liquid, the equilibrium dew point of the first absorbent liquid can be made relatively small, thereby improving the dehumidification efficiency.

[0017] Note that the present invention can be realized in various forms. For example, it can be realized in the form of a system including a dehumidifying device, a control method for these devices and systems, a computer program for causing gas dehumidification to be performed in these devices and systems, a server device for distributing the computer program, a non-temporary storage medium storing the computer program, and the like.

Brief Description of Drawings

[0018] [Figure 1] It is a schematic diagram showing the schematic configuration of the dehumidifying device of the first embodiment. [Figure 2] It is a first diagram for explaining the operation content of the dehumidifying device of the first embodiment. [Figure 3] It is a second diagram for explaining the operation content 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 second embodiment. [Figure 5] It is a schematic diagram showing the schematic configuration of the dehumidifying device of the third embodiment. [Figure 6] It is a schematic diagram showing the schematic configuration of the dehumidifying device of the third embodiment. [Figure 7] It is a schematic diagram showing the schematic configuration of a modified example of the dehumidifying device of the first embodiment.

Modes for Carrying Out the Invention

[0019] <First Embodiment> FIG. 1 is a schematic diagram showing a schematic configuration of a dehumidifying device according to the present embodiment. The dehumidifying device 1 dehumidifies a gas by absorbing water such as water vapor and water droplets contained in the gas into an absorption liquid by a gas-liquid contact method. The dehumidifying device 1 of the present embodiment dehumidifies 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 second absorption tower 12, a first regeneration tower 13, a temperature control unit 14, an evaporator 15, and a control unit 20. The hydrogen gas corresponds to the "target gas" in the claims.

[0020] Here, the absorption liquid used in the dehumidifying device 1 will be described. In the dehumidifying device 1, examples of the absorption liquid that absorbs water contained in the hydrogen gas include ethylene glycols and ionic liquids. The absorption liquid has a vapor pressure of water vapor in a gas-liquid equilibrium that changes according to the temperature of the absorption liquid itself and the water content rate of the absorption liquid. Specifically, when the partial pressure of water vapor is higher than the equilibrium water vapor pressure, the absorption liquid absorbs water so that it becomes the equilibrium water vapor pressure, and when the partial pressure of water vapor is lower than the equilibrium water vapor pressure, the absorption liquid releases water until it becomes the equilibrium water vapor pressure. Therefore, when the contact between the gas and the absorption liquid is sufficient and the gas-liquid equilibrium is reached, the water vapor pressure after dehumidification becomes equal to the equilibrium vapor pressure of the absorption liquid. When the water content in the absorption liquid decreases (the absorption liquid becomes concentrated or lean in moisture), or when the temperature of the absorption liquid decreases, the performance of absorbing water vapor improves and the equilibrium water vapor pressure decreases. On the other hand, when the water content in the absorption liquid increases (the absorption liquid becomes dilute or rich in moisture), or when the temperature of the absorption liquid increases, the performance of absorbing water vapor decreases and the equilibrium water vapor pressure regarding water increases. The dehumidifying device 1 of the present embodiment utilizes such properties of the absorption liquid to dehumidify the hydrogen gas. The dehumidifying device 1 uses an ionic liquid as the absorption liquid. The absorption liquid of the present embodiment corresponds to the "first absorption liquid" described in the claims.

[0021] The first absorption tower 11 is filled with packing material 11a, such as metal or ceramic. Examples of packing material 11a include Raschig rings, Dickson packing, and woven mesh. The first absorption tower 11 is connected to an absorption liquid channel 31 through which the absorption liquid from the first regeneration tower 13 (described later) flows, and an absorption liquid channel 32 through which the 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 20. The first absorption tower 11 is equipped with a heat exchange pipe 11b. A refrigerant capable of cooling the absorption liquid inside the first absorption tower 11 is supplied to the heat exchange pipe 11b.

[0022] The second absorption tower 12 is filled with packing material 12a such as metal or ceramic. Examples of packing material 12a include Raschig rings, Dickson packing, and woven mesh. In addition to the absorbent liquid channel 32 and the absorbent liquid channel 33 through which the absorbent liquid from the second absorption tower 12 flows, the second absorption tower 12 is also connected to a steam channel 34. The steam channel 34 is through which water vapor generated inside the evaporator 15 flows.

[0023] The second absorption tower 12 comprises a pump 12b and a heat exchange pipe 12c. The pump 12b is located in an exhaust passage 12d connected to the second absorption tower 12 and reduces the pressure inside the second absorption tower 12. The exhaust passage 12d is provided with an on / off valve 12e that allows or blocks the flow of fluid in the exhaust passage 12d, and a pressure detection unit 12f that detects the pressure inside the second absorption tower 12. The pressure detection unit 12f outputs the detected pressure to a control unit 20 to which it is electrically connected. The heat exchange pipe 12c is supplied with cooling water at a temperature similar to the ambient temperature, which has been subjected to heat exchange with the atmosphere using, for example, a cooling tower or radiator, from a cooling water supply unit (not shown). The heat exchange pipe 12c cools the absorbent liquid inside the second absorption tower 12.

[0024] The first regeneration tower 13 is filled with packing material 13a such as metal or ceramic. Examples of packing material 13a include Raschig rings, Dickson packing, and woven mesh. In addition to the absorption liquid channel 33 and absorption liquid channel 31, the first regeneration tower 13 is connected to a purge gas channel 6 through which a relatively dry gas, the purge gas, flows. The purge gas channel 6 is equipped with a flow control valve 6a and a heat exchanger 6b. The flow control valve 6a controls the flow rate of the purge gas flowing into the first regeneration tower 13 in response to commands from the electrically connected control unit 20. The heat exchanger 6b reduces the temperature of the purge gas flowing out of the first regeneration tower 13. The first regeneration tower 13 is equipped with a heat exchange pipe 13b that heats the absorption liquid inside the first regeneration tower 13.

[0025] As described above, the first absorption tower 11, the second absorption tower 12, and the first regeneration tower 13 are connected by absorption liquid channels 31, 32, and 33 through which the absorption liquid flows. In this embodiment, absorption liquid channels 31 and 33 are each provided with liquid transfer pumps 31a and 33a. Liquid transfer pump 31a pumps the absorption liquid from the first regeneration tower 13 to the first absorption tower 11. Liquid transfer pump 33a pumps the absorption liquid from the second absorption tower 12 to the first regeneration tower 13. Note that the absorption liquid channels to which the liquid transfer pumps are connected are not limited to these. They may also be connected to absorption liquid channel 32.

[0026] The temperature control unit 14 comprises a cooler 14a, a heater 14b, and a heat exchanger 14c. The cooler 14a is provided in the absorbent liquid channel 31. The cooler 14a cools the absorbent liquid flowing through the absorbent liquid channel 31 using a refrigerant that has cold energy generated in the evaporator 15. The heater 14b is provided in the absorbent liquid channel 33. The heater 14b heats the absorbent liquid flowing through the absorbent liquid channel 33 using a heater or the like. The heat exchanger 14c crosses the absorbent liquid channel 31 and the absorbent liquid channel 33 to perform heat exchange between the absorbent liquid before it is cooled by the cooler 14a and the absorbent liquid before it is heated by the heater 14b. The temperature control unit 14 adjusts the temperature of the absorbent liquid so that the temperature of the absorbent liquid in the first regeneration tower 13 is higher than the temperature of the absorbent liquid in the first absorption tower 11. The cooler 14a corresponds to the "cooling unit" described in the claims.

[0027] The evaporator 15 generates cooling energy by generating water vapor. The evaporator 15 has a heat exchange pipe 15a. The heat exchange pipe 15a is connected to the cooler 14a via refrigerant passages 35 and 36. In this way, the refrigerant with cooling energy generated in the evaporator 15 is supplied to the cooler 14a. The evaporator 15 is connected to a steam passage 34 connected to the second absorption tower 12 and a water supply passage 37. The water supply passage 37 is connected to a water supply unit 37a, such as a water tank, and water supplied from the water supply unit 37a to the evaporator 15 flows through it. The water supply passage 37 is also connected to a heat exchanger 6b provided in the purge gas passage 6, and water flows through it to lower the temperature of the purge gas flowing out of the first regeneration tower 13. Details of the function of the evaporator 15 will be described later. The evaporator 15 corresponds to the "cooling unit" described in the claims.

[0028] The control unit 20 is a computer comprising ROM, RAM, and CPU. The control unit 20 is electrically connected to the flow control valves 5a and 6a, the pump 12b, the pressure detection unit 12f, the liquid transfer pumps 31a and 33a, the water supply unit 37a, etc. The control unit 20 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 20 controls the water supply unit 37a to supply water to the evaporator 15 and drives the pump 12b. When water is supplied to the evaporator 15, water vapor equivalent to the saturated vapor pressure is generated inside the evaporator 15. The water vapor generated inside the evaporator 15 moves inside the steam flow path 34 and inside the second absorption tower 12 which is connected via the steam flow path 34. When the pump 12b is driven, the inside of the second absorption tower 12, the inside of the steam flow path 34, and the inside of the second absorption tower 12 are depressurized, and the amount of substances other than absorbent liquid, water vapor, and water inside these areas is reduced to the minimum.

[0030] In the dehumidification method using the dehumidifier 1, as preparation for dehumidification, the control unit 20 controls the temperature control unit 14 to adjust the temperature of the absorbent liquid in the first regeneration tower 13 so that the temperature of the absorbent liquid in the first absorption tower 11 is higher. The control unit 20 also controls the flow control valve 6a to introduce purge gas into the first regeneration tower 13.

[0031] In the dehumidification method using the dehumidifier 1, first, the flow control valve 5a is controlled in response to a command from the control unit 20 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 absorbent liquid, mainly in the packing material 11a. When hydrogen gas and the 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 absorbent liquid, thus lowering 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 absorption tower 11 in this embodiment is equipped with a heat exchange pipe 11b inside the first absorption tower 11 to cool the absorbent liquid. As a result, the absorbent liquid inside the first absorption tower 11 is at a relatively low temperature, improving the dehumidification efficiency for hydrogen gas. The absorbent liquid that has absorbed the water contained in the hydrogen gas flows through the absorbent liquid flow path 32 and into the second absorption tower 12. The temperature of the absorbent liquid flowing into the second absorption tower 12 is higher than the temperature of the absorbent liquid used to absorb water contained in hydrogen gas in the first absorption tower 11.

[0032] The absorbent liquid flowing into the second absorption tower 12 has already absorbed a sufficient amount of water contained in the hydrogen gas flowing into the first absorption tower 11, but it is still capable of absorbing more water. Inside the second absorption tower 12, there is water vapor equivalent to the saturated vapor pressure generated inside the evaporator 15. In the second absorption tower 12, the absorbent liquid flowing into it mainly absorbs the water vapor inside the second absorption tower 12 through the packing material 12a. As a result, the water vapor pressure inside the evaporator 15, which is in communication with the inside of the second absorption tower 12, decreases to the equilibrium pressure of the absorbent liquid, making it easier for water vapor to be generated. The absorbent liquid that has absorbed water vapor in the second absorption tower 12 is heated by the heat exchanger 14c and the heater 14b and flows into the first regeneration tower 13.

[0033] The absorbent liquid flowing from the second absorption tower 12 to the first regeneration tower 13 is mainly held in the packing material 13a and comes into contact with the purge gas, releasing water into the purge gas and thus being regenerated. The regenerated absorbent liquid flows through the absorbent liquid channel 31 and into the first absorption tower 11. The absorbent liquid flowing through the absorbent liquid channel 31 is cooled by the heat exchanger 14c and the cooler 14a, so it flows into the first absorption tower 11 at a lower temperature than the absorbent liquid in the first regeneration tower 13. The 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] Inside the evaporator 15, as described above, the absorption of water vapor by the absorbent liquid flowing into the second absorption tower 12 makes it easier for water to be converted back into water. As a result, cold energy corresponding to the heat of vaporization of water is generated in the evaporator 15. The cold energy generated in the evaporator 15 lowers the temperature of the refrigerant flowing through the heat exchange pipe 15a of the evaporator 15. The refrigerant flowing through the heat exchange pipe 15a is supplied to the cooler 14a. In other words, the absorbent liquid flowing through the absorbent liquid channel 31 is cooled by the cold energy generated in the evaporator 15 as the absorbent liquid flowing into the second absorption tower 12 absorbs water vapor.

[0035] In the dehumidification method using the dehumidifier 1 of this embodiment, the pressure inside the second absorption tower 12, which is in communication with the inside of the exhaust flow path 12d, is controlled. Specifically, the control unit 20 has a threshold value set in advance for the pressure inside the second absorption tower 12, and when the pressure inside the second absorption tower 12 exceeds the threshold value, the control unit 20 drives the pump 12b to reduce the pressure inside the second absorption tower 12. By doing so, the vacuum level inside the second absorption tower 12 is maintained, making it easier for water vapor to move from the evaporator 15 to the second absorption tower 12.

[0036] In the dehumidifier 1 of this embodiment, the absorbent liquid is used to dehumidify hydrogen gas in the first absorption tower 11. Generally, when dehumidifying a humid gas using an absorbent liquid, the dew point required for the dehumidified gas (dry gas) is often lower than 0°Cdp. Therefore, the absorbent liquid used for dehumidifying the humid gas can further absorb water. Thus, in the dehumidifier 1 of this embodiment, the absorbent liquid used for dehumidifying hydrogen gas is used in the second absorption tower 12 to absorb water vapor inside the evaporator 15. As a result, water vapor is more easily generated from water in the evaporator 15, and thus cold energy corresponding to the heat of vaporization of water is also more easily generated. In the cooler 14a, the refrigerant having the cold energy thus generated in the evaporator 15 is used to cool the absorbent liquid flowing into the first absorption tower 11. In this way, the dehumidifier 1 of this embodiment can generate cold energy that can keep the refrigerant at a relatively low temperature by using the absorbent liquid used for dehumidification.

[0037] Figure 2 is the first diagram illustrating the operation of the dehumidifier 1 of this embodiment. Here, the effects of the dehumidifier 1 of this embodiment will be explained by comparing it with a comparative dehumidifier. 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. Figure 2 shows the equilibrium dew point of the absorbent liquid at three different temperatures (5°C, 20°C, and 80°C). The equilibrium dew point of the absorbent liquid at 5°C is shown by the solid line L5, the equilibrium dew point of the absorbent liquid at 20°C is shown by the solid line L20, and the equilibrium dew point of the absorbent liquid at 80°C is shown by the solid line L80.

[0038] The comparative example dehumidifier does not have the second absorption tower 12 and evaporator 15 that are present in the dehumidifier 1 of this embodiment. Therefore, the temperature of the absorbent liquid flowing into the absorption tower is determined by the degree of cooling by the cooler (corresponding to the cooler 14a provided in the dehumidifier 1). If a refrigerant that has undergone heat exchange with the atmosphere using a cooling tower or radiator is supplied to the cooler, the temperature of the refrigerant supplied to the cooler will be the ambient temperature, for example, around 20°C. In the comparative example dehumidifier, when the water content of the absorbent liquid is around 0.2 wt%, the equilibrium dew point in the dehumidifying absorption tower is around -45°C (indicated by P0 in Figure 2).

[0039] On the other hand, the dehumidifier 1 of this embodiment can reduce the equilibrium dew point in the first absorption tower 11 by lowering the temperature of the absorbent liquid in the second absorption tower 12. In the dehumidifier 1, the refrigerant supplied to the cooler 14a is supplied from the evaporator 15. In the evaporator 15, cooling heat corresponding to the heat of vaporization of water is generated by the absorption of water vapor by the absorbent liquid in the second absorption tower 12. Specifically, if a refrigerant at a temperature similar to the atmosphere, which has undergone heat exchange with the atmosphere using a cooling tower or radiator, is supplied to the heat exchange pipe 12c of the second absorption tower 12, the temperature of the absorbent liquid in the second absorption tower 12 will be about 20°C, and if the water content of the absorbent liquid is about 0.2%, the equilibrium dew point in the second absorption tower 12 will be about -45°C (indicated by P0 in Figure 2). As a result, the evaporator 15 can easily lower the temperature of the refrigerant supplied to the cooler 14a to about 5°C. Therefore, since the absorbent is cooled using a refrigerant at approximately 5°C, the equilibrium dew point in the first absorption tower 11 drops to -52°C dp (indicated by P11 in Figure 2). In other words, the dehumidification efficiency of the first absorption tower 11 can be improved.

[0040] Furthermore, the dehumidifier 1 of this embodiment can increase the water content of the absorbent by lowering the temperature of the absorbent in the second absorption tower 12, thereby increasing the equilibrium dew point in the first regeneration tower 13. Specifically, in the dehumidifier 1, the equilibrium dew point of the absorbent in the first absorption tower 11, which has been cooled to about 5°C by the refrigerant, becomes -45°Cdp when the water content of the absorbent is 0.47 wt% (indicated as P12 in Figure 2), as shown in Figure 2. When the water content of the absorbent becomes 0.47 wt%, the equilibrium dew point of the absorbent at 20°C is -37°Cdp (indicated as P13 in Figure 2), so the temperature of the refrigerant in the evaporator 15 can be easily lowered to about 5°C. In this way, by increasing the water content of the absorbent, for example, the equilibrium dew point in the first regeneration tower 13, where the absorbent is heated to 80°C, can be increased from -15°Cdp (symbol P14 in Figure 2) to -4°Cdp (symbol P15 in Figure 2). Therefore, the regeneration efficiency of the absorbent in the first regeneration tower 13 is improved, and the amount of purge gas required to regenerate the absorbent can be reduced.

[0041] Furthermore, in the explanation using Figure 2, it was assumed that the refrigerant supplied to the dehumidifier is generated by heat exchange with the atmosphere using cooling towers or radiators. Refrigerant can also be generated by cooling with a chiller. However, generating refrigerant with a chiller may result in relatively high power consumption if the refrigerant temperature is to be kept relatively low.

[0042] Figure 3 is a second diagram illustrating the operation of the dehumidifier 1 of this embodiment. Similar to Figure 2, Figure 3 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. In addition to the solid line L5 showing the equilibrium dew point of the absorbent liquid at 5°C and the solid line L80 showing the equilibrium dew point of the absorbent liquid at 80°C, Figure 3 also shows the equilibrium dew point of the absorbent liquid at 40°C with the solid line L40.

[0043] In this embodiment, when the temperature of the refrigerant supplied from the outside is, for example, about 40°C, which is about the same as the ambient temperature in summer, the temperature of the absorbent liquid in the second absorption tower 12 will be about 40°C. When the water content of the absorbent liquid is about 0.2%, the equilibrium dew point in the second absorption tower 12 will be about -34°C (indicated by P16 in Figure 3). However, in the evaporator 15, it is possible to lower the temperature of the refrigerant supplied to the cooler 14a to about 5°C. As a result, the absorbent liquid is cooled using a refrigerant at about 5°C, and the equilibrium dew point in the first absorption tower 11 will drop to -52°Cdp (indicated by P17 in Figure 3). Thus, even when generating a refrigerant by exchanging heat with the atmosphere using a cooling tower or radiator in a high-temperature environment where the ambient temperature is 40°C, the equilibrium dew point in the first absorption tower 11 is relatively lowered, thereby improving the dehumidification efficiency of the first absorption tower 11.

[0044] As described above, according to the dehumidifier 1 of this embodiment, the cooler 14a uses the heat of vaporization generated when water vapor is produced in the evaporator 15 as cooling energy to cool the absorbent liquid that the first regeneration tower 13 returns to the first absorption tower 11. The water vapor generated in the evaporator 15 is absorbed by the absorbent liquid in the second absorption tower 12 connected to the evaporator 15. As a result, the temperature of the cooling energy generated by the cooler 14a can be kept relatively low, and the equilibrium dew point of the absorbent liquid in the first absorption tower 11 can be kept relatively low. Therefore, the dehumidification efficiency in the first absorption tower 11 can be improved.

[0045] Furthermore, according to the dehumidifier 1 of this embodiment, the water content of the absorbent liquid can be increased by lowering the temperature of the absorbent liquid in the second absorption tower 12, thereby increasing the equilibrium dew point in the first regeneration tower 13. As a result, the regeneration efficiency of the absorbent liquid in the first regeneration tower 13 is improved, and the amount of purge gas required to regenerate the absorbent liquid can be reduced.

[0046] Furthermore, according to the dehumidifier 1 of this embodiment, when the pressure inside the second absorption tower 12 exceeds a preset threshold, the control unit 20 drives the pump 12b to reduce the pressure inside the second absorption tower 12. This reduces the amount of foreign matter, such as gas molecules other than water vapor, that may hinder the movement of water vapor inside the second absorption tower 12 and the evaporator 15 connected to the second absorption tower 12, making it easier for water vapor to move from the evaporator 15 to the second absorption tower 12. Therefore, the dehumidification efficiency of the dehumidifier 1 can be further improved.

[0047] Furthermore, according to the dehumidifier 1 of this embodiment, the second absorption tower 12 uses the absorbent liquid obtained by absorbing water in the first absorption tower 11 to absorb water vapor generated inside the evaporator 15. This allows only one type of absorbent liquid to be used for dehumidification. Therefore, the configuration of the dehumidifier 1 is relatively simple, and the cost required for dehumidification can be reduced.

[0048] Furthermore, according to the dehumidifier 1 of this embodiment, the dehumidifier 1 uses a mixed gas containing hydrogen and water, generated by a water electrolysis device, as the target gas, and absorbs the water contained in the mixed gas with an absorbent liquid. This makes it possible to effectively utilize the hydrogen generated by the water electrolysis device.

[0049] Furthermore, in the dehumidifier 1 of this embodiment, since the absorbent liquid is an ionic liquid with almost no vapor pressure, its movement to the evaporator 15 is suppressed. Therefore, mixing of the absorbent liquid and water in the evaporator 15 can be suppressed, and thus the dehumidification efficiency of the dehumidifier 1 can be maintained.

[0050] Furthermore, according to the dehumidification method of this embodiment, the heat of vaporization generated when water vapor is produced is used as cooling to cool the absorbent liquid that the first regeneration tower returns to the first absorption tower. Since the generated water vapor is absorbed by the second absorbent liquid in the second absorption tower, the temperature of the generated cooling can be made relatively low. Therefore, the equilibrium dew point of the absorbent liquid in the first absorption tower 11 can be made relatively small, thereby improving the dehumidification efficiency.

[0051] Furthermore, according to the computer program of this embodiment, the control unit 20 causes the dehumidifier 1 to function so that the heat of vaporization when water vapor is generated is used as cooling to cool the absorbent liquid that the first regeneration tower 13 returns to the first absorption tower 11. Since the generated water vapor is absorbed by the second absorbent liquid in the second absorption tower 12, the temperature of the generated cooling can be made relatively low. Therefore, when the water contained in the target gas is absorbed by the absorbent liquid, the equilibrium dew point of the absorbent liquid can be made relatively small, thereby improving the dehumidification efficiency.

[0052] <Second Embodiment> Figure 4 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, instead of a cooler that cools the absorbent liquid, an evaporator that generates cooling by generating water vapor is connected to the absorbent liquid flow path.

[0053] The dehumidifier 2 of this embodiment comprises a first absorption tower 11, a second absorption tower 12, a first regeneration tower 13, a temperature control unit 44, and a control unit 20. The temperature control unit 44 of this embodiment comprises an evaporator 44a, a heater 14b, and a heat exchanger 14c. The temperature control unit 44 adjusts the temperature of the absorbent liquid so that the temperature of the absorbent liquid in the first regeneration tower 13 is higher than the temperature of the absorbent liquid in the first absorption tower 11.

[0054] The evaporator 44a is located in the absorbent liquid channel 31. The evaporator 44a is connected to the water supply unit 37a via the water supply channel 37, and is capable of temporarily storing water inside. The inside of the evaporator 44a is connected to the steam channel 34. As a result, the water vapor generated inside the evaporator 44a is absorbed by the absorbent liquid from which hydrogen gas has been dehumidified in the second absorption tower 12. Therefore, cooling is easily generated in the evaporator 44a by the generation of water vapor. The cooling generated in the evaporator 44a directly cools the absorbent liquid flowing through the absorbent liquid channel 31. The evaporator 44a corresponds to the "cooling unit" described in the claims.

[0055] As described above, according to the dehumidifier 2 of this embodiment, the water vapor generated in the evaporator 44a, which generates cold energy for cooling the absorbent liquid, is absorbed into the absorbent liquid in the second absorption tower 12 connected to the evaporator 44a. This allows the temperature of the cold energy generated by the evaporator 44a to be kept relatively low, and thus the equilibrium dew point of the absorbent liquid in the first absorption tower 11 can be made relatively small. Therefore, the dehumidification efficiency in the first absorption tower 11 can be improved.

[0056] Furthermore, according to the dehumidifier 2 of this embodiment, the evaporator 44a is provided in the absorbent liquid channel 31, and the cooling generated in the evaporator 44a can be directly transferred to the absorbent liquid flowing through the absorbent liquid channel 31. As a result, the absorbent liquid can be cooled efficiently, which further reduces the equilibrium dew point of the absorbent liquid in the first absorption tower 11 and further improves the dehumidification efficiency of the first absorption tower 11.

[0057] <Third Embodiment> Figure 5 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 first embodiment (Figure 1) in that it supplies a portion of the dry hydrogen gas, from which water has been absorbed in the absorption tower, as a purge gas to the regeneration tower.

[0058] The dehumidifier 3 of this embodiment comprises a first absorption tower 11, a second absorption tower 12, a first regeneration tower 13, a temperature control unit 14, an evaporator 15, a purge gas supply unit 50, and a control unit 20. The purge gas supply unit 50 is provided to connect the first absorption tower 11 and the first regeneration tower 13.

[0059] The purge gas supply unit 50 includes purge gas flow paths 51 and 52, a flow control valve 51a, and a purge gas cooler 52a. The purge gas flow path 51 is connected to the first absorption tower 11 and the first regeneration tower 13, and is configured so that a portion of the gas inside the first absorption tower 11 flows toward the first regeneration tower 13. The gas flowing through the purge gas flow path 51 is hydrogen gas (dry gas) with relatively low humidity, from which water has been removed in the first absorption tower 11. The purge gas flow path 52 is connected to the first regeneration tower 13 and the first absorption tower 11, and is configured so that the gas inside the first regeneration tower 13 flows toward the first absorption tower 11. The gas flowing through the purge gas flow path 52 is hydrogen gas with relatively high humidity, containing water released from the absorbent liquid in the first regeneration tower 13.

[0060] The flow control valve 51a is connected to the purge gas flow path 51. The flow control valve 51a controls the flow rate of relatively low-humidity hydrogen gas flowing into the first regeneration tower 13 in response to commands from the electrically connected control unit 20.

[0061] The purge gas cooler 52a is connected to the purge gas flow path 52. The purge gas cooler 52a cools the relatively humid hydrogen gas flowing inside the purge gas flow path 52 and removes water from the hydrogen gas by condensing at least some of the water vapor contained in the hydrogen gas. The hydrogen gas cooled by the purge gas cooler 52a returns to the first absorption tower 11.

[0062] In the dehumidifier 3 of this embodiment, the refrigerant with cold energy generated in the evaporator 15 is supplied to a cooler 14a connected to the absorbent liquid flow path 31 and a purge gas cooler 52a connected to the purge gas flow path 52. Specifically, as shown in Figure 5, the refrigerant supplied by the evaporator 15 flows through the refrigerant flow path 38 and is supplied to the purge gas cooler 52a. The refrigerant supplied to the purge gas cooler 52a cools the relatively humid hydrogen gas flowing through the purge gas flow path 52, then flows through the refrigerant flow path 39 and is supplied to the cooler 14a. The refrigerant supplied to the cooler 14a flows through the refrigerant flow path 36 and returns to the evaporator 15, where it is cooled again by the cold energy generated by the generation of water vapor. Note that the method of supplying the refrigerant with cold energy generated in the evaporator 15 is not limited to this. The refrigerant may be supplied to the cooler 14a and then to the purge gas cooler 52a, or it may be supplied in parallel to the cooler 14a and the purge gas cooler 52a.

[0063] As described above, according to the dehumidifier 3 of this embodiment, the water vapor generated in the evaporator 15, which generates cold energy for cooling the absorbent liquid, is absorbed into the absorbent liquid in the second absorption tower 12 connected to the evaporator 15. This makes it possible to relatively lower the equilibrium dew point of the absorbent liquid in the first absorption tower 11, thereby improving the dehumidification efficiency in the first absorption tower 11.

[0064] Furthermore, according to the dehumidifier 3 of this embodiment, in the first regeneration tower 13, a mixed gas from which at least a portion of the contained water has been removed in the first absorption tower 11, i.e., a relatively dry gas, is used as a purge gas to release water from the absorbent liquid, thus enabling efficient water release from the absorbent liquid. The purge gas that has released water from the absorbent liquid is cooled by a purge gas cooler 52a connected to the purge gas flow path 52, and after at least a portion of the absorbed water is removed, it returns to the first absorption tower 11. In this way, the purge gas for releasing water from the absorbent liquid can be circulated inside the dehumidifier 3, so the amount of purge gas taken in from the outside is reduced or becomes unnecessary. This further improves the dehumidification efficiency of the dehumidifier 3.

[0065] <Fourth Embodiment> Figure 6 is a schematic diagram showing the general configuration of the dehumidifier of the fourth embodiment. The dehumidifier of the fourth embodiment differs from the dehumidifier of the first embodiment (Figure 1) in that the absorbent liquid that absorbs water vapor in the second absorption tower is a different absorbent liquid from the absorbent liquid that dehumidifies hydrogen gas in the dehumidifying absorption tower.

[0066] The dehumidifier 4 of this embodiment includes a first absorption tower 11, a first regeneration tower 13, a temperature control unit 14, an evaporator 15, a second absorption tower 61, a second regeneration tower 63, and a control unit 20. In the dehumidifier 4, the absorbent liquid circulating between the first absorption tower 11 and the first regeneration tower 13 and the absorbent liquid circulating between the second absorption tower 61 and the second regeneration tower 63 are separate absorbent liquids. In the dehumidifier 4, the absorbent liquid circulating between the first absorption tower 11 and the first regeneration tower 13 and the absorbent liquid circulating between the second absorption tower 61 and the second regeneration tower 63 are not mixed. The dehumidifier 4 uses an ionic liquid as the absorbent liquid circulating between the second absorption tower 61 and the second regeneration tower 63. Hereinafter, the absorbent liquid circulating between the first absorption tower 11 and the first regeneration tower 13 will be referred to as the "first absorbent liquid," and the absorbent liquid circulating between the second absorption tower 61 and the second regeneration tower 63 will be referred to as the "second absorbent liquid." The first absorbent liquid and the second absorbent liquid may be of the same type, or they may be of different types.

[0067] The evaporator 15 is connected to steam channels 81 and 82, respectively. Steam channel 81 is connected to the second regeneration tower 63, and water from inside the second regeneration tower 63 flows through it. Steam channel 81 is equipped with a cooler 81a to cool the water flowing through it. Steam channel 82 is connected to the second absorption tower 62, and water vapor from inside the evaporator 15 flows through it.

[0068] The second absorption tower 61 is filled with packing material 61a such as metal or ceramic. Examples of packing material 61a include Raschig rings, Dixon packing, and woven mesh. The second absorption tower 61 is connected to an absorption liquid channel 71 through which the second absorbent liquid from the second regeneration tower 63 (described later) flows, an absorption liquid channel 73 through which the second absorbent liquid from the second absorption tower 61 flows, and a steam channel 82. The second absorption tower 61 absorbs the water vapor flowing in from the evaporator 15, mainly in the packing material 61a, into the second absorbent liquid. The second absorption tower 61 is equipped with a heat exchange pipe 61b that cools the second absorbent liquid inside the second absorption tower 61 by supplying cooling water at a moderate temperature from a cooling water supply unit (not shown).

[0069] The second regeneration tower 63 is filled with packing material 63a such as metal or ceramic. Examples of packing material 63a include Raschig rings, Dickson packing, and woven mesh. The second regeneration tower 63 is connected to an absorption liquid channel 73, an absorption liquid channel 71, and a steam channel 81. The second regeneration tower 63 primarily releases water from the second absorption liquid that has absorbed water vapor in the second absorption tower 61, through the packing material 63a. This regenerates the second absorption liquid. The second regeneration tower 63 is equipped with a heat exchange pipe 63b for heating the second absorption liquid inside the second regeneration tower 63.

[0070] As described above, the second absorption tower 61 and the second regeneration tower 63 are connected by absorption liquid channels 71 and 73 through which the second absorption liquid flows. In this embodiment, liquid transfer pumps 71a and 73a are provided in the absorption liquid channel 71 and the absorption liquid channel 73, respectively. Liquid transfer pump 71a pumps the second absorption liquid from the second regeneration tower 63 to the second absorption tower 61. Liquid transfer pump 73a pumps the second absorption liquid from the second absorption tower 61 to the second regeneration tower 63.

[0071] The temperature control unit 74 comprises a cooler 74a, a heater 74b, and a heat exchanger 74c. The cooler 74a is located in the absorbent liquid channel 71. The cooler 74a cools the second absorbent liquid flowing through the absorbent liquid channel 71 using a refrigerant. The heater 74b is located in the absorbent liquid channel 73. The heater 74b heats the absorbent liquid flowing through the absorbent liquid channel 73 using a heater or the like. The heat exchanger 74c crosses the absorbent liquid channel 71 and the absorbent liquid channel 73, performing heat exchange between the second absorbent liquid before it is cooled by the cooler 74a and the second absorbent liquid before it is heated by the heater 74b. The temperature control unit 74 adjusts the temperature of the second absorbent liquid so that its temperature in the second regeneration tower 63 is higher than its temperature in the second absorbent liquid in the second absorption tower 61.

[0072] In the dehumidifier 4 of this embodiment, exhaust passages 83 and 84 are connected to the steam passage 81 and steam passage 82, respectively. The exhaust passage 83 connected to the steam passage 81 is provided with an on / off valve 83a that allows or blocks the flow of fluid in the exhaust passage 83. The exhaust passage 84 connected to the steam passage 82 is provided with an on / off valve 84a that allows or blocks the flow of fluid in the exhaust passage 84, and a pressure detection unit 84b that detects the pressure inside the exhaust passage 84. The exhaust passages 83 and 84 are connected to a pump 85. The pump 85 reduces the pressure inside the steam passages 81 and 82. In this embodiment, since the steam passage 82 is a passage for water vapor inside the evaporator 15 to move to the second absorption tower 61, the control unit 20 drives the pump 85 according to the pressure detected by the pressure detection unit 84b to reduce the pressure inside the steam passage 82. This minimizes the amount of substances other than the second absorbent liquid, water vapor, and water inside the steam passage 82.

[0073] As described above, according to the dehumidifier 4 of this embodiment, the water vapor generated in the evaporator 15, which generates cold energy for cooling the first absorbent liquid, is absorbed into the second absorbent liquid in the second absorption tower 61 connected to the evaporator 15. This makes it possible to relatively lower the equilibrium dew point of the absorbent liquid in the first absorption tower 11, thereby improving the dehumidification efficiency in the first absorption tower 11.

[0074] Furthermore, according to the dehumidifier 4 of this embodiment, the dehumidifier 4 comprises a combination of a first absorption tower 11 and a first regeneration tower 13 through which a first absorbent liquid that absorbs water contained in hydrogen gas is circulated, and a combination of a second absorption tower 61 and a second regeneration tower 63 through which a second absorbent liquid that absorbs water vapor generated in the evaporator 15 is circulated. As a result, water vapor generated in the evaporator 15 can be stably absorbed, and dehumidification can be stably performed in the first absorption tower 11, to which a sufficiently cooled first absorbent liquid is supplied.

[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, a pump is provided to reduce the pressure inside the second absorption tower and the steam flow path. The control unit drives the pump to reduce the pressure inside the second absorption tower when the pressure inside the second absorption tower exceeds a threshold. The conditions for driving the pump are not limited to this. It is also sufficient to reduce the pressure inside the second absorption tower and the steam flow path before the dehumidifier first starts dehumidifying. Furthermore, a pump is not required, but by using a pump to reduce the pressure inside the second absorption tower and the steam flow path, the vacuum level inside the second absorption tower and the steam flow path can be maintained, making it easier for water vapor to move from the evaporator to the second absorption tower.

[0077] [Differentiation 2] The dehumidifiers of the second and fourth embodiments may also include a purge gas supply unit, which is also included in the dehumidifier of the third embodiment. By including a purge gas supply unit, the amount of purge gas taken in from outside the dehumidifier is reduced or eliminated, thereby further improving the dehumidification efficiency of the dehumidifier.

[0078] [Difference 3] The dehumidifiers of the second and third embodiments may include a second regeneration tower, which is also present in the dehumidifier of the fourth embodiment. By including the second regeneration tower, water vapor generated in the evaporator can be stably absorbed, thereby enabling stable dehumidification in the first absorption tower to which the cooled first absorbent liquid is supplied.

[0079] [Differentiation Example 4] 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] [Difference 5] In the above-described embodiment, the first absorption tower 11 is provided with a heat exchange pipe 11b that supplies a refrigerant capable of cooling the absorbent liquid inside the first absorption tower 11. The refrigerant supplied to this heat exchange pipe 11b may be supplied, for example, by an evaporator 15.

[0081] Figure 7 is a schematic diagram showing the general configuration of a modified example of the dehumidifier of the first embodiment. In the dehumidifier 1 shown in Figure 7, the refrigerant supplied by the evaporator 15 passes through the refrigerant flow path 35a and is first supplied to the heat exchange pipe 11b of the first absorption tower 11. The refrigerant supplied to the heat exchange pipe 11b passes through the refrigerant flow path 35b and is supplied to the cooler 14a, and then passes through the refrigerant flow path 36 and returns to the evaporator 15. As a result, the absorbent liquid (first absorbent liquid) in the first absorption tower 11 is kept at a relatively low temperature, which improves the dehumidification efficiency in the first absorption tower 11.

[0082] [Modification 6] 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.

[0083] [Difference 7] In the first, second, and third embodiments, an ionic liquid was used as the absorbent liquid for absorbing water contained in the mixed gas. In the fourth embodiment, an ionic liquid was used as the absorbent liquid circulating between the second absorption tower 61 and the second regeneration tower 63. However, in the dehumidifiers of the above embodiments, the absorbent liquid for absorbing water and water vapor is not limited to an ionic liquid. It may also be ethylene glycols as described above.

[0084] 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.

[0085] <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 that releases water from the first absorbent liquid that has absorbed water in 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 cooling unit that generates cold energy by generating water vapor and cools the first absorbent liquid that returns from the first regeneration tower to the first absorption tower, The system comprises a second absorption tower connected to the cooling section, which absorbs water vapor generated in the cooling section into a second absorbent liquid, Dehumidifier. <Application Example 2> The dehumidifier described in Application Example 1 further, A pump to reduce the pressure inside the aforementioned second absorption tower, A pressure detection unit for detecting the pressure inside the second absorption tower, The system includes a control unit that controls the pump using the internal pressure of the second absorption tower detected by the pressure detection unit, When the pressure inside the second absorption tower exceeds a preset threshold, the control unit drives the pump to reduce the pressure inside the second absorption tower. Dehumidifier. <Application Example 3> A dehumidifier described in Application Example 1 or Application Example 2, The second absorption tower is supplied with the first absorption liquid, which has absorbed water in the first absorption tower. The second absorbent solution is the first absorbent solution that has absorbed water in the first absorption tower. 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 first regeneration tower and brings it into contact with the first absorbent liquid, thereby releasing water from the first absorbent liquid as a purge gas. The aforementioned purge gas supply unit is, A purge gas channel is connected to the first regeneration tower and the first absorption tower, and returns the purge gas, which has released water from the first absorption liquid in the first regeneration tower, back to the first absorption tower. The system includes a purge gas cooler connected to the purge gas flow path and used to cool the purge gas flowing through the purge gas flow path. Dehumidifier. <Application Example 5> The dehumidifying device described in any one of the examples from Application Example 1 to Application Example 4 further, A second regeneration tower that releases water from the second absorbent liquid that has absorbed water vapor in the second absorption tower, comprising a second regeneration tower that returns the second absorbent liquid from which water has been released back to the second absorption tower, The second absorption tower absorbs the water vapor generated in the cooling section into the second absorbent liquid returning from the second regeneration tower. Dehumidifier. <Application Example 6> A dehumidifying device described in any one of Application Examples 1 to 5, The aforementioned target gas is a mixed gas containing hydrogen and water, produced by a water electrolysis device. Dehumidifier. <Application Example 7> A dehumidifying device described in any one of the examples from Application Example 1 to Application Example 6, The first absorbent solution is an ionic liquid. Dehumidifier. <Application Example 8> 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 regeneration step in which water is released from the first absorbent liquid that has absorbed water in the first absorption step, comprising a regeneration step in which the first absorbent liquid from which water has been released is returned to the first absorbent tower in a regeneration tower, A cooling step in which cold energy is generated by generating water vapor and the first absorption liquid returning from the regeneration tower to the first absorption tower is cooled, The system includes a second absorption step in which the water vapor generated in the cooling step is absorbed by a second absorbent liquid. Dehumidification method. <Application Example 9> 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 regeneration function that releases water from the first absorbent liquid that has absorbed water by the first absorption function, the regeneration function that returns the first absorbent liquid from which water has been released to the first absorption tower in a regeneration tower, A cooling function that generates cold energy by generating water vapor and cools the first absorption liquid that returns from the regeneration tower to the first absorption tower, A second absorption function is provided, which involves absorbing the water vapor generated by the cooling function into a second absorbent liquid, and the computer is instructed to perform this function. Computer program. [Explanation of symbols]

[0086] 1,2,3,4…Dehumidifier 11…First absorption tower 12,61... Second absorption tower 12e,85… pump 12f, 84b... Pressure detection unit 13…1st regeneration tower 14a…Cooler 15… Evaporator 20... Control Unit 50... Purge gas supply unit 51, 52… Purge gas flow path 52a... Purge gas cooler 63…Second Regeneration Tower

Claims

1. A dehumidifier, A first absorption tower absorbs water contained in the target gas into a first absorption liquid, A first regeneration tower that releases water from the first absorbent liquid that has absorbed water in the first absorption tower, the first regeneration tower that returns the first absorbent liquid from which water has been released back to the first absorption tower, A cooling unit that generates cold energy by generating water vapor and cools the first absorbent liquid that returns from the first regeneration tower to the first absorption tower, The system comprises a second absorption tower connected to the cooling section, which absorbs water vapor generated in the cooling section into a second absorbent liquid, Dehumidifier.

2. The dehumidifying device according to claim 1 further, A pump to reduce the pressure inside the second absorption tower, A pressure detection unit for detecting the pressure inside the second absorption tower, The system includes a control unit that controls the pump using the internal pressure of the second absorption tower detected by the pressure detection unit, When the pressure inside the second absorption tower exceeds a preset threshold, the control unit drives the pump to reduce the pressure inside the second absorption tower. Dehumidifier.

3. A dehumidifying device according to claim 1 or claim 2, The second absorption tower is supplied with the first absorption liquid, which has absorbed water in the first absorption tower. The second absorbent solution is the first absorbent solution obtained by absorbing water in the first absorption tower. Dehumidifier.

4. The dehumidifying device according to claim 1 or claim 2 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 first regeneration tower and brings it into contact with the first absorbent liquid, thereby releasing water from the first absorbent liquid as a purge gas. The aforementioned purge gas supply unit is, A purge gas flow path is connected to the first regeneration tower and the first absorption tower, and returns the purge gas, which has released water from the first absorption liquid in the first regeneration tower, back to the first absorption tower. The system includes a purge gas cooler connected to the purge gas flow path and used to cool the purge gas flowing through the purge gas flow path. Dehumidifier.

5. The dehumidifying device according to claim 1 or claim 2 further, A second regeneration tower for releasing water from the second absorbent liquid that has absorbed water vapor in the second absorption tower, comprising a second regeneration tower for returning the second absorbent liquid from which water has been released back to the second absorption tower. The second absorption tower absorbs the water vapor generated in the cooling section into the second absorbent liquid returning from the second regeneration tower. Dehumidifier.

6. A dehumidifying device according to claim 1 or claim 2, The aforementioned target gas is a mixed gas containing hydrogen and water, produced by a water electrolysis device. Dehumidifier.

7. A dehumidifying device according to claim 1 or claim 2, The second absorbent solution is an ionic liquid. Dehumidifier.

8. 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 regeneration step in which water is released from the first absorbent liquid that has absorbed water in the first absorption step, comprising a regeneration step in which the first absorbent liquid from which water has been released is returned to the first absorption tower in a regeneration tower, A cooling step in which cold energy is generated by generating water vapor and the first absorption liquid returning from the regeneration tower to the first absorption tower is cooled, The system includes a second absorption step in which the water vapor generated in the cooling step is absorbed by a second absorbent liquid. Dehumidification method.

9. 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 regeneration function that releases water from the first absorbent liquid that has absorbed water by the first absorption function, the regeneration function that returns the first absorbent liquid from which water has been released to the first absorption tower in a regeneration tower, A cooling function that generates cold energy by generating water vapor and cools the first absorbent liquid that returns from the regeneration tower to the first absorption tower, A second absorption function is performed by causing the computer to absorb the water vapor generated by the cooling function into the second absorption liquid. Computer program.

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