System and method for dehumidifying air

Abstract

A system and method for dehumidifying an air stream intended for a process, manufacturing area, or residential building. The system includes a conditioning device for absorbing moisture from the air into a liquid desiccant. The system includes a desiccant dryer for evaporating the absorbed moisture from the liquid desiccant to evaporated moisture. The system includes a condenser for condensing the evaporated moisture. The system includes a heat transfer medium flow circuit configured such that heat removed from the evaporated moisture during condensation in the condenser is absorbed by a heat transfer medium, said heat being used during evaporation of the absorbed moisture from the liquid desiccant.

Description

Technical Field

[0001] The present invention relates to systems and methods for dehumidifying air streams, for example intended for processes, manufacturing areas or residential buildings. More particularly, the present invention relates to air dehumidification systems and methods comprising the chemical absorption of water vapor from air by a liquid absorbent and the removal of moisture from the absorbent. More particularly, the present invention relates to systems and methods for regenerating liquid absorbents by evaporating moisture contained therein. Background Art

[0002] Air dehumidification systems are generally used in processes, process areas or residential buildings that require the supply of dry air at a lower or more stable humidity ratio than that available from the outdoors. Humidity control is significant in many settings: for human health in, for example, office and commercial buildings; for certain industrial drying processes in process areas where condensation and mold formation must be eliminated; and for avoiding frost formation in low-temperature freezing processes.

[0003] Desiccant dehumidification processes use a hygroscopic drying material to absorb moisture or water vapor from air, thereby lowering the humidity level in the air to a desired value. The drying material can be solid (e.g., silica gel, molecular sieves) or liquid (concentrated salt solutions such as lithium chloride, calcium chloride, or lithium bromide). The desiccant dehumidification process requires less energy than that of conventional vapor compression systems.

[0004] Dehumidification of air with liquid desiccants is known to occur in packed towers, with the liquid sprayer at the top of the tower and the air inlet at the bottom. Solid desiccants are typically applied as a surface layer on porous material through which an airflow is guided. The use of solid desiccants may have the disadvantage of being costly for larger airflows. Another disadvantage of using solid desiccants may be that high temperatures are required for desiccant regeneration. Finally, a disadvantage is that known control devices using solid desiccants may generally not be suitable for additional functions incorporated into the control device, such as air cooling or scrubbing to mitigate airborne microorganisms.

[0005] Patent Document 1 relates to a liquid desiccant dehumidifier and a liquid desiccant air conditioning device equipped with an absorption air conditioning device and a liquid desiccant dehumidifier. The dehumidifier includes a liquid desiccant absorption device for absorbing moisture contained in the air that enters the dehumidifier and passes through the desiccant absorption device. Patent Document 1 provides a liquid desiccant air conditioning device that does not require a compression device.

[0006] Patent Document 2 discloses a method and control system for operating a liquid desiccant air conditioning system for efficiently maintaining target temperature and humidity levels in a space, the system discharging relatively hot, humid air during operation.

[0007] Patent Document 3 discloses a heat pump in a dehumidifying air conditioning system, in which a compressor is connected to a first condenser, a second condenser, and an evaporator via a coolant pipeline. The first and second condensers are also connected to an evaporator (via the coolant pipeline). The condensers are configured to condense a coolant. The evaporators are configured to cool liquid water guided through a chilled water circuit. During operation, the dilution solution of the regenerator is pressurized by a solution pump, heated by the first condenser, and then sprayed into the filling plate of the regenerator. The regenerator and dehumidifier are located in different positions, and the humid air from the regenerator is discharged to the outside. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] WO99 / 32841 [Patent Document 2] WO2019 / 089971 [Patent Document 3] CN108954625 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The objective is to provide a system for dehumidifying air and / or a method for dehumidifying air that eliminates, or at least mitigates, the aforementioned drawbacks. More generally, the objective is to provide an improved air dehumidification system and / or method for dehumidifying air. In this specification, dehumidification may also be defined as dehumidification, and vice versa. [Means for solving the problem]

[0010] Therefore, in a first embodiment, an air dehumidification system is provided. The air dehumidification system comprises a control device configured to absorb moisture from the air into a liquid desiccant. The control device may comprise, for example, a packed column. The liquid desiccant may include concentrated salt solutions such as lithium chloride, calcium chloride, and / or lithium bromide. The air dehumidification system further comprises a desiccant dryer configured to evaporate the moisture absorbed from the liquid desiccant to become evaporated moisture. The desiccant dryer may comprise a shell and at least one heat transfer tube, or a packed column. The air dehumidification system comprises a condenser configured to condense the evaporated moisture (in particular, to condense the evaporated water into liquid water). The condenser may comprise at least one heat transfer tube. The air dehumidification system comprises a heat transfer medium flow circuit configured such that heat removed from the evaporated moisture during condensation in the condenser is absorbed by a heat transfer medium, and the absorbed heat is used for the evaporation of the absorbed moisture from the liquid desiccant. The temperature, volume, and / or pressure within the air dehumidification system can be selected so that absorbed moisture evaporates from the liquid desiccant in the desiccant dryer, and / or the evaporated moisture condenses in the condenser. The temperature, volume, and / or pressure within the heat transfer medium flow circuit can be selected so that the heat transfer medium condenses in the desiccant dryer, or, for example, in a heat exchanger associated with the desiccant dryer, and / or the heat transfer medium evaporates in the condenser. Heat can be transferred to and from the heat transfer medium using convection, conduction, and / or radiation. The air dehumidification system may be more energy efficient due to its use of heat from condensation during evaporation (the system does not discharge moist air, especially liquid water, during operation).

[0011] Optionally, the condenser comprises at least one cooling tube, the cooling tube having a first surface for condensation of evaporated water, which forms part of a heat transfer medium flow circuit. The first surface may be the outer surface of the cooling tube. The cooling tube can be cooled internally by the heat transfer medium during use.

[0012] Optionally, the heat transfer medium flow circuit includes a compressor downstream of at least one cooling tube. The compressor may be located upstream of the desiccant dryer and / or upstream of the heat exchanger. The compressor is configured to increase the pressure of the heat transfer medium.

[0013] Optionally, the condenser is configured to discharge the condensed moisture in liquid form. The condensed moisture may contain water, or may be water.

[0014] In optional cases, the pressure in the desiccant dryer is substantially equal to the pressure in the condenser during use. During use, the pressure at which moisture is removed from the desiccant in the desiccant dryer may be substantially equal to the pressure at which this moisture condenses in the condenser.

[0015] In the optional configuration, the pressure in the desiccant dryer differs from the pressure in the condenser by less than 50 Pascals during use. The pressure of the moisture and liquid desiccant in the desiccant dryer may differ from the pressure of the moisture in the condenser by, for example, 10 to 20 Pascals during use. The pressure at which moisture is removed from the desiccant in the desiccant dryer differs from the pressure at which this moisture condenses in the condenser by less than 50 Pascals, such as 10 to 20 Pascals.

[0016] In optional configurations, the pressure in the desiccant drying unit and / or the pressure in the condensing unit is below atmospheric pressure. The pressure of moisture and / or liquid desiccants may be below atmospheric pressure at the time of use.

[0017] In an optional configuration, the system is configured such that the mechanical power of the compressor contributes to the heat used for evaporation. The energy applied to the heat transfer medium by the compressor can be transferred to the desiccant dryer, for example, by condensation of the heat transfer medium in the desiccant dryer or in a heat exchanger associated with the desiccant dryer.

[0018] Optionally, the compression device is configured to pressurize the heat transfer medium such that the heat transfer medium changes from vapor to liquid. The phase change of the heat transfer medium from vapor to liquid may occur in the desiccant drying device or in a heat exchanger.

[0019] Optionally, the desiccant drying device comprises at least one heating tube, the at least one heating tube forms part of a heat transfer medium flow circuit and has a second surface thereon for evaporation of moisture absorbed from the liquid desiccant. The pressure of the liquid desiccant at the first surface may be substantially equal to the pressure of the liquid desiccant at the second surface. The second surface may be an outer surface of the at least one heating tube.

[0020] Optionally, the at least one heating tube is configured such that, in use, the liquid desiccant flows along the outer surface of the at least one heating tube in a falling film. The desiccant drying device may comprise a vertical shell and tube heat exchanger.

[0021] Optionally, the at least one heating tube is further configured such that the heat transfer medium condenses inside the at least one heating tube. The at least one heating tube may be positioned vertically.

[0022] Optionally, the heat transfer medium flow circuit further comprises a heat exchanger upstream of the desiccant drying device for enabling transfer of heat from the heat transfer medium to the liquid desiccant. The heat exchanger may be positioned downstream of the compression device in the heat transfer medium flow circuit.

[0023] Optionally, the desiccant drying device and the condensing device are arranged within a common enclosure. The desiccant drying device may be arranged adjacent to the condensing device inside the common enclosure. The desiccant drying device may be arranged below the condensing device within the common enclosure. The condensing device may have an access port on an upper side thereof for evaporated moisture. The condensing device may be placed on top of the desiccant drying device, and vice versa.

[0024] Optionally, the desiccant drying device comprises a packed column. The packed tower comprises a container filled with packing material, as known in the prior art. The packed tower may have a desiccant spray section thereon.

[0025] Optionally, one or more parts of the desiccant drying device are corrosion resistant to liquid desiccant, or the structure of the desiccant drying device is configured to withstand the pressure of the heat transfer medium.

[0026] Optionally, the heat transfer medium comprises a coolant.

[0027] Optionally, the heat transfer medium is configured such that the pressure ratio for compression of the heat transfer medium and the suction capacity flow rate are minimized.

[0028] According to a second aspect, there is provided a method for dehumidifying air. The method comprises the step of absorbing moisture from air into a liquid desiccant. The method comprises the step of evaporating the absorbed moisture from the liquid desiccant to obtain evaporated moisture. The method comprises the step of condensing the evaporated moisture, wherein the heat released during condensation of the evaporated moisture is absorbed by the heat transfer medium, and said heat is used in the evaporation of the absorbed moisture from the liquid desiccant. Accordingly, the additional energy required for regenerating the liquid desiccant, that is, for evaporating the absorbed moisture from the liquid desiccant, can be minimized.

[0029] Optionally, the method further comprises the step of discharging moisture condensed from the liquid desiccant in liquid form.

[0030] Optionally, the method further comprises the step of compressing the heat transfer medium after condensing the evaporated moisture.

[0031] Optionally, the heat transfer medium is pressurized such that said heat transfer medium can change from vapor to liquid.

[0032] In the optional scenario, the mechanical power used to compress the heat transfer medium contributes to the heat used for evaporation.

[0033] In the optional configuration, the heat transfer medium is compressed to reach the pressure and temperature required for heat release necessary for the evaporation of moisture from the liquid desiccant.

[0034] In the case of optional selection, absorbed water evaporates at a first pressure, evaporated water condenses at a second pressure, and the first pressure is substantially equal to the second pressure.

[0035] In the case of arbitrary selection, the first pressure differs from the second pressure by less than 50 Pascals.

[0036] In the optional case, the first pressure and / or the second pressure are below atmospheric pressure.

[0037] Optionally, the liquid desiccant flows along the outer surface of at least one tube within the flowing film during the evaporation of absorbed moisture from the liquid desiccant, and optionally, the heat transfer medium condenses inside at least one tube.

[0038] It should be understood that any of the embodiments, characteristics, and options described in reference to an air dehumidification system are equally applicable to methods for dehumidifying air, and vice versa. Furthermore, it is clear that one or more of the above embodiments, characteristics, and options can be combined.

[0039] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. [Brief explanation of the drawing]

[0040] [Figure 1] This is a schematic diagram of an air dehumidification system. [Figure 2] This figure shows an example of a schematic diagram of an air dehumidification system that includes a drying device and a condensing device in a separate enclosure. [Figure 3]This figure shows an example of a schematic diagram of an air dehumidification system that includes an integrated drying and condensing unit within a common enclosure. [Figure 4] This figure shows an example of a flow chart for an air dehumidification method. [Modes for carrying out the invention]

[0041] Figure 1 shows a diagram of an air dehumidification system. The air dehumidification system in Figure 1 has several relevant drawbacks that the present invention seeks to mitigate. The system comprises a control unit 1. The control unit 1 includes a packed tower 2 on which a liquid desiccant spray unit 3 is mounted, a liquid pump 4 for circulating the desiccant 12 on the packed tower 2, a fresh air supply connection pipe 7, and an exhaust fan 5 for removing dehumidified air 8 from the control unit 1. The packed tower 2 contains a container filled with packing material. In the figure, the packing material is schematically shown as a hatched area. When in use, the desiccant 12 takes in moisture from the fresh air 7 inside the packed tower 2. The moisture-laden liquid desiccant 12 can collect at the bottom of the container. The supply temperature of the desiccant to the spray unit 3 is controlled by a cooling unit 6 to a sufficiently low temperature so that the vapor pressure of the air entering the container is greater than that of the desiccant 12 in the packed tower 2. For this purpose, the desiccant cooling unit 6 is connected to cooling circuits 9, 10 which can use cold water or evaporating coolant from a cooling system.

[0042] The system further includes a regeneration unit 14. The regeneration unit 14 includes a packed tower 15 with a desiccant spray unit 16 on top of it, a liquid pump 17 for circulating the desiccant on the packed tower, a fresh air supply connection pipe 20, and an exhaust fan 18 for removing moist air 21 from the regeneration unit 14. During use, the air draws moisture from the desiccant inside the packed tower 15. Thus, in this system, moisture is removed from the regeneration unit in the form of steam. The supply temperature of the desiccant to the spray unit 16 is controlled by a heating unit 19 to a sufficiently high temperature so that the steam pressure of the desiccant is greater than that of the air 20 inside the packed tower 15. For this purpose, the desiccant heating unit 19 is connected to heating circuits 22 and 23 which can use hot water or steam from a hot water system or steam boiler.

[0043] After drawing water from the air inside the control unit 1, the diluted desiccant 12 is transported from the control unit 1 to the regenerator 14 via the connecting line 11 and the heat exchanger 13. Similarly, after draining water inside the regenerator 14, the condensed desiccant 25 is transported from the regenerator 14 to the control unit 1 via the connecting line 24 and the heat exchanger 13. The function of the heat exchanger 13 is to preheat the relatively cold diluted desiccant 12 by heat transfer from the relatively warm condensed desiccant 25. The open communication line 26 ensures that any possible difference in the desiccant liquid level between the control unit 1 and the regenerator 14 is equalized.

[0044] While the dehumidifying process for wet desiccants is generally considered relatively energy-efficient compared to conventional coolers applied for this purpose, the energy use of these systems is even more pronounced for the following reasons: Apart from some power for the circulation pump 4 and exhaust fan 5, the regulating device 1 requires energy to cool the cooling circuits 9, 10 for a sensible cooling of the airflow 7 from the supply temperature of new air to the desired, generally lower injection temperature of the dry airflow 8. Another contribution to energy use is the latent heat associated with the condensation of vapor from the airflow 7 being dried onto the desiccant 12, which is typically 2400 to 2500 kJ per kg of condensed vapor. In addition to this latent heat, the enthalpy of dilution (typically 100 to 300 kJ / kg of dissolved vapor) is also carried to the desiccant. The described contributions to the heat load are discharged into the cooling circuits 9 and 10 via the cooling device 6.

[0045] The moisture absorbed by the desiccant 12 in the control unit 1 must be removed again from the desiccant in the regeneration unit 14. This regeneration process also consumes energy. Apart from some power for the circulation pump 17 and exhaust fan 18, the regeneration unit 14 requires thermal energy from heating circuits 22, 23 through heating unit 19 for the sensible heating of the airflow 20 and 21 from supply to exhaust temperature. In addition to this, there is the latent heat associated with the evaporation of moisture from the desiccant, which is typically 2400 to 2500 kJ per kg of evaporated vapor. Furthermore, the enthalpy of dissolution (typically 100 to 300 kJ / kg of water extracted from the desiccant) must be supplied to remove the dissolved moisture from the desiccant. The sum of these described contributions is supplied by heating circuits 22, 23 through heating unit 19.

[0046] Therefore, the energy usage of the dehumidifying process is quite large, consisting of energy requirements for heat dissipation from the control unit 1 to the cooling system 6 and heat supply from the heating system 19 to the regeneration unit 14. More specifically, the latent heat and energy for dilution associated with the absorption of a unit mass of water by the desiccant must be transferred twice, first through the cooling unit 6 to the cooling circuits 9 and 10, and then through the heating unit 19 from the heating circuits 22 and 23. Furthermore, there are losses associated with undesirable, perceptible heat exchange between the desiccant and the airflow through the packed columns 2 and 15 inside the control unit 1 and the regeneration unit 14, respectively.

[0047] For example, various attempts to reduce the energy requirements of the desiccant dehumidification process have been described in the literature, such as integrating a heat pump into the control unit 1 to cool the new airflow 7, and using that energy to heat the airflow 20 to the regenerator 14. This solution can also be combined with a solar thermal collector to supply solar energy to the heating unit 19. Another option is to install a so-called twin-coil system that indirectly heats the new supply airflow 20 to the control unit 14 with heat from the exhaust airflow 21. It is also possible to reduce moisture buildup on the desiccant dehumidification system by pre-drying the airflow 7 with a conventional cooler that has high efficiency, or by partially recirculating the air discharged from the process area.

[0048] What the above solutions have in common is that the above-mentioned perceptible and latent heat energy requirements still exist, albeit somewhat less. Other known drawbacks of known wet desiccant dehumidification processes include the expensive desiccant from the regenerator associated with the humid air discharge flow 21, contamination of the desiccant by substances from the fresh air 20 into the regenerator 14, the sensitivity of the regenerator process to external climate influences, the need for higher desiccant temperatures and higher airflow rates in the regenerator in humid climates when the humidity ratio of the flow 20 is relatively high due to the resulting higher temperature loss from the regenerator 14 and higher energy demands of the heating device 19, and the need for installation space in an external location to ensure a free air supply / discharge to the regenerator. In certain climates, external installations require means of freeze protection for the regenerator.

[0049] Figure 2 shows a diagrammatic example of an air dehumidification system 30 according to the present invention. In this example, the air dehumidification system comprises a dryer and a condenser. Here, the dryer and condenser are provided in separate enclosures. The desiccant to be dehumidified is supplied in 31 to a desiccant dryer 40, which comprises a shell 40A with internally heated tubes 28. The desiccant is dehumidified inside the shell space of the desiccant dryer 40 at a specific, in this example, below atmospheric pressure, thereby the formed water vapor (i.e., moisture) is discharged to the condenser 41 via a connecting pipe 35. The moisture then condenses inside the shell of the condenser 41 outside the internally cooled tubes 48 at substantially the same, in this example, below atmospheric pressure. The pressure difference between the vapors inside the dryer 40 and the condenser 41 is preferably less than 50 Pascals. In this example, the pressure difference is between 10 and 20 Pascals. The formed condensate is discharged from a condensate outlet 49, where a condensate pump 36 pressurizes the condensate from below atmospheric pressure to atmospheric pressure. The condensate (i.e., liquid water) is discharged through the condensate drain 37. Therefore, in this example, the water is discharged in liquid form.

[0050] The latent heat due to the condensation of moisture outside the tube 48 is released by the phase change of the coolant liquid 51 into the coolant vapor 42. The pressure at which this phase change occurs is typically considerably higher than the pressure below atmospheric pressure at which moisture evaporates from the desiccant in the drying unit 40 and the condensing unit 41.

[0051] The coolant vapor is transported to the coolant compressor 43, which pressurizes it to a sufficiently high pressure, thereby allowing a second phase change of the coolant from vapor to liquid to occur inside the tube 28 of the drying apparatus 40 at a sufficiently high temperature level to achieve adequate drying of the liquid desiccant on the outer surface of the tube 28.

[0052] Optionally, the inner tubes 28 of the drying apparatus 40 can be positioned upright and mounted between two horizontal sheets, one at the lower end and one at the upper end of the tubes. In this configuration, the liquid desiccant can flow downward in a thin film along the outer surface of these tubes 28, allowing for high heat transfer between the tube walls and the film of flowing desiccant. The flowing film can be established by horizontal plates 47 mounted below the desiccant inlet connection 31 and near the upper ends of the vertical tubes 28. The plates 47 can have centered holes around each tube with a hole diameter slightly larger than the outer diameter of the tubes 28, establishing small gaps around each tube 28 for the passage of the desiccant and initiating the unfolding of the flowing film. The dried desiccant can be collected at the top of the lower tube sheet 32, from where it is discharged through the desiccant outlet 50 to the desiccant pump 34 and returned to the control device 1.

[0053] Optionally, the condensed coolant liquid 51 may be collected in the space within the shell of the desiccant dryer 40, just above the coolant outlet 45 and below the lower tube seat 32.

[0054] In this example, the drying agent 11 from the control device is preheated in the heat exchanger 13 by a backflow with the dried drying agent 24 from the drying device 40.

[0055] Optionally, an additional heating device 19 may be incorporated into the desiccant supply line to the desiccant dryer 40, for example, to initiate the evaporation process or for other control purposes, such as indirectly heating the desiccant with heat from hot water or steam circuits 22, 23.

[0056] Optionally, the condenser 46 may be incorporated into the coolant circuit to dissipate excess heat from this circuit if the available condensation heat due to the coolant phase change from 44 to 45 exceeds the heat requirements of the desiccant dryer 40.

[0057] The desiccant drying apparatus 40 has pipes 28 and a shell 40A, which must be manufactured from materials resistant to the corrosive properties of the desiccant commonly applied. The pipes must be able to withstand the high pressure from the coolant. Applicable constituent materials for drying apparatus that meet these requirements, such as titanium, are known to be rare and expensive. Therefore, another possible embodiment of the present invention is presented, which has essentially the same operating principle as the embodiment in Figure 2 but mitigates the drawbacks described. This alternative embodiment is shown in Figure 3.

[0058] Figure 3 shows an example diagram of an air dehumidification system that includes an integrated drying unit 40 and a condensing unit 41 within a common enclosure.

[0059] The embodiment shown in Figure 3 includes several items having the same names and functions as the embodiment in Figure 2. These similar items are indicated by the same reference numerals. For brevity, the description of the operating principle of the embodiment in Figure 3 will be limited to the parts that differ from those in Figure 2. In the embodiment of Figure 3, the drying apparatus 40 and the condensing apparatus 41 are integrated within a common enclosure 40B, which is, for example, a cylindrical shell with a closed end. In this example, Figure 3 shows a cross-sectional view of this shell 40B in a plane oriented perpendicular to the longitudinal axis of the shell.

[0060] The desiccant to be dried is supplied to the drying apparatus at 31 and then distributed by a spraying device 56 on a corrosion-resistant packed column 57 on which the drying process takes place, for example. The packed column is surrounded at the sides and bottom by a corrosion-resistant holder 40C, which is manufactured from, for example, a type of relatively inexpensive plastic material. Above this holder, and therefore at the steam outlet, a corrosion-resistant de-icing device 59 is provided to prevent any possible carryover of the desiccant. It is preferable that the desiccants 56, 57, 58 and 59, as well as all items that come into contact with the supply connection 31 and the discharge connection 50, be manufactured from a corrosion-resistant plastic material, since the strength of the most commonly applied plastics is sufficient for the applications according to this embodiment.

[0061] Steam from the defrosting unit 59 flows freely through various channels 35 to a steam condenser 41 located at the top of the shell 40B of the drying / condensing unit, at a low speed, for example, less than 5 m / s, with negligible pressure loss. This steam condenser 41 comprises a bundle of numerous internally cooled tubes 48. The coolant flowing through the tubes 48 preferably evaporates inside the tubes 48. The outer surfaces of these tubes are only exposed to clean steam during the condensation process. The tubes 48 must therefore withstand the internal pressure of the coolant 42, but do not have to be made of highly corrosion-resistant material. Thus, in this embodiment, materials commonly applied to cooling tube bundles, such as steel, copper, or stainless steel, are applicable to this item 48.

[0062] The coolant vapor is transported from the tube 48 to the coolant compressor 43, which pressurizes it to a sufficiently high pressure, thereby enabling a second phase change of the coolant from vapor to liquid to occur inside the heat exchanger 63. The heat exchanger 63 preheats the moist desiccant before distribution on the packed tower in order to promote the evaporation of moisture in the drying unit 40.

[0063] Therefore, the heat removed from the water evaporated during condensation in the condenser is absorbed by the heat transfer medium, and this heat is used for the evaporation of the absorbed water from the liquid desiccant. After the condensation of the coolant in the heat exchanger 63, the condensed coolant 51 is collected in the receiving container 64 and prepared for supply to the tube 48 again. The internal space of the condenser 41 is preferably accessible only from above to ensure a downward flow direction of steam inside the condenser 41. The steam flow in the condenser may then be flowing in the opposite direction to the condensant evaporating inside the tube 48, which is here mainly an upward flow direction. Steam access from above can be achieved by sealing the sides 60 and bottom 61 of the condenser 41. In this example, the formed condensate is collected on the inclined bottom plate 61 below the tube bundle 48 and discharged through the condensate outlet pipe 49. A condensate pump 36 can pressurize the condensate from a pressure below atmospheric pressure to atmospheric pressure. The liquid condensate is discharged through the condensate drain 37.

[0064] Non-condensable gases can be discharged into the atmosphere through a perforated pipe 62 located near the center of the pipe bundle 48. A vacuum pump 38 can connect pipe 62 to a discharge pipe 39.

[0065] The dried desiccant is discharged from the drying system 40 via the outlet connection 50 and supplied to the circulation pump 52. A portion of the desiccant 24 is returned to the control unit. In this example, another portion passes through the heating / cooling unit 53. This heating / cooling unit 53 indirectly provides extra heat to the desiccant circuit if the supply temperature of the desiccant to be dried to the drying unit 40 is too low, and cools the desiccant to be dried if this temperature is too high. This temperature stabilization process can therefore be carried out by changing the temperature of the secondary circuits 54, 55. It is clearly preferable that the heat capacity of this heating / cooling unit 53 be minimal and used only for starting the cooling system or for small temperature corrections during operation. The main heat source of the system for evaporation and dissolution of moisture, in this example, is provided by the condensation of the coolant 44, namely by the condenser 63. The objective of the system according to the present invention is to provide an energy-efficient solution for removing absorbed moisture from the desiccant. This can be achieved by reusing the latent heat released by moisture condensation inside the condenser and by transferring this latent heat to the evaporating coolant liquid. The enthalpy of this coolant can be further increased by mechanical energy transfer from the compressor to the coolant to a level high enough to provide the latent heat required for the enthalpy of water evaporation and dissolution necessary to evaporate and separate water from the desiccant inside the drying apparatus. That is, the energy for the water evaporation process from the desiccant, and for the dissolution of this water, is supplied from a secondary circuit that receives energy from the condensation of evaporated water, and from the mechanical compressor.

[0066] This method of energy reuse makes the process highly energy efficient. Another objective of the present invention is to achieve this goal with commercially available standard components at a relatively low cost. This is achieved by selecting a coolant with optimal physical properties and is intended for compressors with relatively small pressure ratios and small suction volume flow rates. This is typically, for example, a pressure ratio of 3 to 5 and a compressor flow rate of 0.5 to 1 m 3This can be achieved using a coolant R1234ze with a specific volume of aspirated vapor within the range of water removed from the desiccant per kg of suction capacity. These requirements for the compressor are more easily achievable with commercially available equipment than those for known mechanical steam compression systems.

[0067] The typically large evaporation area of ​​packed columns, the arrangement of the defrosting equipment, the steam rise rate well below 5 m / s, and the typically low pressures prevailing inside the enclosure, for example, less than 100 millibars, do not anticipate the undesirable carryover of expensive desiccants from moisture drying toward the condensate drain.

[0068] Furthermore, for example, the desiccant drying process according to the present invention does not require fresh air from the outside for moisture removal, so its thermal performance is independent of external climatic conditions. The system according to the present invention is therefore suitable for internal installation, in which case no additional freeze protection measures are required.

[0069] The vertical configuration in Figure 2 and the alternative embodiment in Figure 3, which features an integrated drying and condensing unit within a common enclosure, require a minimum of, for example, 10 m 2 It requires less than a certain floor area, which is another advantage of the present invention.

[0070] Figure 4 shows an example of air dehumidification method 100.

[0071] Therefore, in the first step 102, moisture is absorbed from the air into the liquid desiccant. The absorbed moisture evaporates from the liquid desiccant in step 104, becoming evaporated moisture. The evaporated moisture condenses in step 106, and the heat released during the condensation of the evaporated moisture is absorbed by the heat transfer medium in step 108, and this heat is used for the evaporation of the absorbed moisture from the liquid desiccant. Step 108 can be performed after or in parallel with step 106. The heat for evaporating moisture from the desiccant in step 106 can be provided by the condensation of the heat transfer medium. The heat released during the condensation of the evaporated moisture can be used in step 108 for the evaporation of the heat transfer medium. In this example, after the evaporated moisture is condensed in step 106, the heat transfer medium is compressed in step 110. The condensed moisture is discharged from the liquid desiccant in liquid form in step 112. The discharge step 112 can be performed before step 108 and / or 110, after step 108 and / or 110, or in parallel with step 108 and / or 110.

[0072] In this specification, the present invention is described with reference to specific examples of embodiments of the invention. However, it is evident that various modifications and changes may be made herein without departing from the essence of the invention. For the purpose of concise and accurate description, characteristics are described herein as part of the same or different embodiments, but alternative embodiments are also conceivable that have all or some combinations of the characteristics described in these other embodiments.

[0073] However, other forms of modification, variation, and alternative forms are also possible. The specification, drawings, and examples should therefore be considered illustrative rather than restrictive.

[0074] For the purpose of concise and accurate description, features are described herein as being the same or as part of different embodiments, but it should be understood that the scope of the invention may include embodiments having all or some combinations of the described features. In the claims, any reference numerals in parentheses should not be construed as limiting the claims. The term “equipped with” does not preclude the existence of features or steps other than those listed in the claims.

[0075] Furthermore, the words "a" and "an" should not be interpreted as limiting to "only one," but rather as meaning "at least one," and do not exclude plurals. The mere fact that certain means are mentioned in different claims does not indicate that combinations of these means cannot be used for merit. [Explanation of Symbols]

[0076] 1 Adjustment device 2 Packed tower 3. Liquid desiccant section 4. Liquid pump 5. Exhaust fan 6 Cooling device 7 Fresh air 8. Dehumidified air 9 Cooling circuit 10 Cooling circuit 12. Desiccant 14 Playback device 15 Packed tower 16 Desiccant spray section 17 Liquid pump 18 Exhaust Fan 19 Heating device 20 New air supply connection pipes 21 Humid air 22 Heating circuit 23 Heating circuit 24 connection lines 25 Desiccant 28 tube 30 Air Dehumidification System 31 Desiccant inlet connection 34 Desiccant pump 35 connecting pipes 36 Condensate pump 37 Condensate drain 40 Drying equipment 41 Condenser 45 Coolant outlet 47 Plates 48 tube 49 Condensate outlet 50 Desiccant outlet 51 Coolant liquid 52 Circulation pump 54 Secondary circuit 55 Secondary circuit 56 Spraying device 57 Packed tower 59 Defrost device 60 Side 61 Bottom

Claims

1. A control device for absorbing moisture from the air into the liquid desiccant, A desiccant drying apparatus for evaporating the moisture absorbed from the liquid desiccant to obtain evaporated moisture, A condensing apparatus for condensing the evaporated water, An air dehumidification system comprising a heat transfer medium flow circuit configured such that the heat removed from the evaporated water during condensation in the condensing device is absorbed by the heat transfer medium, and the heat is used for the evaporation of the absorbed water from the liquid desiccant, The heat transfer medium includes a coolant. The condensing apparatus comprises at least one cooling tube, the at least one cooling tube forming part of the heat transfer medium flow circuit and having a first surface thereon for condensing the evaporated water. The heat transfer medium flow circuit includes a compressor downstream of at least one cooling tube. The heat transfer medium flow circuit further comprises a heat exchanger upstream of the desiccant drying apparatus for enabling heat transfer from the heat transfer medium to the liquid desiccant in an air dehumidification system.

2. The air dehumidification system according to claim 1, wherein the condensing device is configured to discharge condensed moisture in liquid form, the condensed moisture being water, and the system includes a condensate drain for discharging the liquid.

3. The air dehumidification system according to claim 1 or 2, wherein, during use, the absorbed moisture evaporates at a first pressure, the evaporated moisture condenses at a second pressure, and the difference between the first pressure and the second pressure is less than 50 Pascals.

4. The air dehumidification system according to claim 1, wherein the pressure in the desiccant drying device and / or the pressure in the condensing device is less than atmospheric pressure.

5. The air dehumidification system according to claim 1, wherein the compressor is configured such that the mechanical power of the compressor contributes to the heat used for evaporation.

6. The air dehumidification system according to claim 1, wherein the compression device is configured to pressurize the heat transfer medium so that the heat transfer medium changes from vapor to liquid.

7. The air dehumidification system according to claim 1, wherein the desiccant drying apparatus comprises at least one heating tube, the at least one heating tube forming part of the heat transfer medium flow circuit and having a second surface thereon for evaporation of the absorbed moisture from the liquid desiccant, and the condensing apparatus comprises a bundle of tubes.

8. The air dehumidification system according to claim 7, wherein the system is configured such that the heat transfer medium condenses inside the at least one heating tube.

9. The air dehumidification system according to claim 1, wherein the heat transfer medium flow circuit includes a receiving container for collecting the coolant condensed from the heat exchanger of the heat transfer medium flow circuit.

10. An additional heating device incorporated into the desiccant supply line to the desiccant drying apparatus, and / or The air dehumidification system according to claim 1, further comprising a heat exchanger for preheating the desiccant to be dried, which is connected to a dried desiccant from the desiccant drying apparatus and a backflow heat exchanger.

11. The air dehumidification system according to claim 1, wherein the desiccant drying device and the condensing device are arranged in a common enclosure.

12. The air dehumidification system according to claim 1, wherein the desiccant drying apparatus comprises a packed tower.

13. The air dehumidification system according to claim 1, wherein one or more parts of the desiccant drying apparatus are corrosion-resistant to the liquid desiccant, or the structure of the desiccant drying apparatus is configured to withstand the pressure of the heat transfer medium.

14. The liquid desiccant absorbs moisture from the air, The steps include: evaporating the absorbed moisture from the liquid desiccant to obtain evaporated moisture; A method for dehumidifying air, comprising the step of condensing the evaporated moisture, The heat released during the condensation of the evaporated water is absorbed by a heat transfer medium, the heat transfer medium contains a coolant, and the heat is used during the evaporation of the absorbed water from the liquid desiccant. The method further includes the step of condensing the evaporated water and then compressing the heat transfer medium, wherein the heat transfer medium is pressurized so that it can change from vapor to liquid. A method comprising using a heat exchanger upstream of a desiccant drying apparatus for evaporating moisture absorbed from the liquid desiccant to obtain evaporated moisture, wherein a heat exchanger is used to transfer heat from the heat transfer medium to the liquid desiccant.

15. The method according to claim 14, further comprising the step of discharging condensed moisture from the liquid desiccant in liquid form.

16. The method according to claim 14 or 15, further comprising the step of compressing the heat transfer medium after condensing the evaporated water.

17. The method according to claim 16, wherein the heat transfer medium is pressurized so that it can change from vapor to liquid.

18. The method according to claim 16, wherein the mechanical power used to compress the heat transfer medium contributes to the heat used for evaporation.

19. The method according to claim 16, wherein the heat transfer medium is compressed to reach a pressure and temperature necessary for heat release to evaporate the moisture from the liquid desiccant.

20. The method according to claim 14, wherein the absorbed water evaporates at a first pressure, the evaporated water condenses at a second pressure, and the difference between the first pressure and the second pressure is less than 50 Pascals.

21. The method according to claim 20, wherein the first pressure and / or the second pressure are less than atmospheric pressure.

22. The method according to claim 14, wherein the liquid desiccant flows along the outer surface of at least one tube in a flowing film during the evaporation of the absorbed moisture from the liquid desiccant, and the heat transfer medium condenses inside the at least one tube.

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