Compressed air dehumidifier

Abstract

To provide a compressed air dehumidifier capable of being operated with good responsiveness even in a high load state by property returning lubricating oil circulated together with a refrigerant from a compressor of a refrigeration cycle to the compressor.SOLUTION: In a compressed air dehumidifier which includes a dehumidifier housing 30 having an evaporator 14 of a refrigeration cycle device 10 installed in the inside, the evaporator 14 is integrally formed with the dehumidifier housing 30 as a plate-type heat exchanger, a refrigerant inlet 14a of the evaporator is disposed at a lower side, and a refrigerant outlet 14b of the evaporator is disposed at an upper side. There are provided: a lubricating oil return piping 20 whose upstream side is connected to a refrigerant piping 15 between an expansion valve 13 and the refrigerant inlet 14a of the evaporator, and whose downstream side is connected to a refrigerant return piping 15a between the refrigerant outlet 14b of the evaporator and a compressor 11; a proportional control solenoid valve 22 which is connected to a portion piped so as to be positioned in a middle part of the lubricating oil return piping 20 and below the refrigerant inlet 14a of the evaporator, and is arranged so as to adjust a flow quantity of return lubricating oil; and a control unit 60 which controls the valve.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a compressed air dehumidifier that is provided with a refrigeration cycle device equipped with a compressor, a condenser, an expansion valve, and an evaporator, and a dehumidifier housing in which the evaporator of the refrigeration cycle device is installed so as to cool the compressed air introduced from an air compressor and dehumidify the moisture in the compressed air by condensing it, the evaporator being formed integrally with the dehumidifier housing as a plate-type heat exchanger, with an evaporator refrigerant inlet provided below the evaporator through which refrigerant is introduced and an evaporator refrigerant outlet provided above the evaporator through which refrigerant is discharged. [Background technology]

[0002] An example of a conventional compressed air dehumidifier has been proposed by the present applicant, which includes a plate-type heat exchanger that is provided with an air inlet, an air outlet, a drain outlet, a refrigerant inlet and a refrigerant outlet, and that dehumidifies the compressed air by condensing moisture contained in the compressed air by exchanging heat between the compressed air in a first space and the refrigerant in a second space, a control unit that controls the operation of the refrigeration cycle, a lubricating oil discharge pipe for discharging lubricating oil remaining in the second space into the refrigerant pipe, and a solenoid valve that adjusts the flow rate of fluid moving through the lubricating oil discharge pipe, and when the control unit detects a predetermined high load state, it executes a "first process" by controlling the solenoid valve to increase the flow rate of fluid moving through the lubricating oil discharge pipe (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-124565 A (Page 1) Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved with respect to the compressed air dehumidifier is that in the case of the evaporator of the refrigeration cycle device composed of a plate-type heat exchanger, the flow path for the refrigerant is greatly expanded in the evaporator, so that the lubricant oil is not returned to the compressor of the refrigeration cycle device, and since the solenoid valve installed in the conventional lubricant oil return pipe (for example, the lubricant oil discharge pipe described in Patent Document 1) is ON / OFF open / close controlled, when the solenoid valve is opened, the return lubricant oil flows suddenly, and the refrigerant also flows in a bypass, causing a sudden change in dew point. In this way, there is a problem that the compressed air dehumidifier cannot be operated with good responsiveness, especially when a large amount of return lubricant oil is generated under high load conditions, because it is not possible to properly control the return lubricant oil to be returned to the compressor at the right time.

[0005] Furthermore, in the invention described in Patent Document 1, the lubricating oil discharge pipe is located below the refrigerant inlet of the evaporator and is directly connected to the evaporator, and this configuration makes it easy for a large amount of lubricating oil (return lubricating oil) to accumulate in the vertical space at the lower end of the evaporator where the refrigerant inlet of the evaporator and the lubricating oil discharge pipe are connected, resulting in the problem that it is difficult to responsively return the return lubricating oil to the compressor.

[0006] Therefore, an object of the present invention is to provide a compressed air dehumidifier that can operate responsively even under high load conditions by appropriately returning lubricating oil contained in a refrigerant and circulating from the compressor of a refrigeration cycle device to the compressor. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention has the following configuration. According to one embodiment of the compressed air dehumidifier of the present invention, a refrigeration cycle device including a compressor, a condenser, an expansion valve, and an evaporator is provided, and a dehumidifier housing is provided in which the evaporator of the refrigeration cycle device is installed so as to cool the compressed air introduced from the air compressor and condense the moisture in the compressed air to dehumidify it, the evaporator is formed integrally with the dehumidifier housing as a plate-type heat exchanger, a refrigerant inlet of the evaporator through which a refrigerant is introduced is provided below the evaporator, and a refrigerant outlet of the evaporator through which the refrigerant is discharged is provided above the evaporator. The wetting device is equipped with a lubricating oil return pipe whose upstream side is connected to a refrigerant pipe between the expansion valve and the refrigerant inlet of the evaporator and whose downstream side is connected to a refrigerant return pipe which is a refrigerant pipe between the refrigerant outlet of the evaporator and the compressor, so that return lubricating oil returned to the compressor is returned to the compressor, bypassing the evaporator; a proportional control solenoid valve connected to a portion of the lubricating oil return pipe that is piped to be located below the refrigerant inlet of the evaporator and arranged to adjust the flow rate of the return lubricating oil; and a control device that controls the proportional control solenoid valve.

[0008] In addition, according to one aspect of the compressed air dehumidifier of the present invention, a volume of a flow passage of the lubricant return pipe is smaller than a volume of a flow passage of the refrigerant return pipe.

[0009] In addition, according to one embodiment of the compressed air dehumidifier of the present invention, a capillary tube that regulates the flow of the return lubricant oil returned to the compressor is connected to a midpoint of the lubricant oil return pipe.

[0010] In addition, according to one embodiment of the compressed air dehumidifier of the present invention, the capillary tube is connected downstream of the flow of the return lubricant oil, which is on the compressor side, relative to the portion of the lubricant return piping to which the proportional control solenoid valve is connected.

[0011] Furthermore, according to one embodiment of the compressed air dehumidifier of the present invention, the dehumidifier is provided with at least one of a discharge pipe temperature sensor that measures the refrigerant temperature at the refrigerant outlet side of the compressor, a high-pressure pressure sensor that measures the refrigerant pressure at the refrigerant outlet side of the condenser, and a dew point sensor that measures the dew point of the secondary-side compressed air that has been dehumidified by heat exchange by the evaporator in the dehumidifier housing, and is characterized in that the at least one sensor is connected to the control device that determines the load state of the refrigeration cycle device based on detection information from the at least one sensor and controls the proportional control solenoid valve in accordance with the load state.

[0012] In addition, according to one embodiment of the compressed air dehumidifier of the present invention, the upstream return piping, which is the piping upstream of the proportional control solenoid valve in the flow of the return lubricant oil of the lubricant oil return piping, can be characterized in that it is insulated by a thermal insulating material.

[0013] In addition, according to one embodiment of the compressed air dehumidification device of the present invention, the downstream return piping, which is the piping downstream of the proportional control solenoid valve in the flow of the return lubricating oil of the lubricating oil return piping, can be characterized in that it is arranged in a position where it is heated by exhaust heat from a refrigeration cycle device.

[0014] Furthermore, according to one embodiment of the compressed air dehumidifier of the present invention, the dehumidifier housing is provided to dehumidify primary-side compressed air introduced from an air compressor by heat exchange and discharge the dehumidified secondary-side compressed air, a heat exchanger is provided inside the dehumidifier housing in two stages, a first heat exchanger unit and a second heat exchanger unit, the first heat exchanger unit is provided by arranging a pre-cooling flow path for the primary-side compressed air and a reheating flow path for the secondary-side compressed air so as to pre-cool the primary-side compressed air and reheat the secondary-side compressed air so as to intersect, and the second heat exchanger unit is provided to dehumidify the compressed air pre-cooled in the first heat exchanger unit by cooling it with the evaporator to cause condensation. Effect of the Invention

[0015] The compressed air dehumidifier of the present invention has the particularly advantageous effect of being able to operate with good responsiveness even under high load conditions by appropriately returning lubricating oil contained in the refrigerant and circulating from the compressor of the refrigeration cycle device to the compressor. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic diagram showing an example of a compressed air dehumidifier according to the present invention; [Diagram 2] FIG. 2 is a schematic diagram showing an example of a plate-type heat exchanger that is a component of the compressed air dehumidifier according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Next, an embodiment of a compressed air dehumidifier according to the present invention will be described in detail with reference to the accompanying drawings (FIGS. 1 and 2).

[0018] The compressed air dehumidifier of the present invention has, as its basic configuration, a refrigeration cycle device 10 equipped with a compressor 11, a condenser 12, an expansion valve 13 and an evaporator 14, and a dehumidifier housing 30 in which the evaporator 14 of the refrigeration cycle device 10 is installed so as to cool the compressed air introduced from the air compressor and dehumidify the moisture in the compressed air by condensing it, the evaporator 14 is formed integrally with the dehumidifier housing 30 as a plate-type heat exchanger, an evaporator refrigerant inlet 14a through which refrigerant is introduced is provided below the evaporator 14, and an evaporator refrigerant outlet 14b through which refrigerant is discharged is provided above the evaporator 14.

[0019] In addition, the lower side (bottom, lower end, lower part) refers to the lower side (bottom, lower end, lower part) in the direction along the vertical direction. Similarly, the upper side (top, upper end, upper part) refers to the upper side (top, upper end, upper part) in the direction along the vertical direction.

[0020] In addition, the compressed air dehumidifier of the present invention is equipped with a lubricant return pipe 20, which is connected at its upstream side to refrigerant pipe 15 between the expansion valve 13 and the refrigerant inlet 14a of the evaporator, and is connected at its downstream side to refrigerant return pipe 15a, which is the refrigerant pipe 15 between the refrigerant outlet 14b of the evaporator and the compressor 11, so that return lubricant oil returned to the compressor 11 bypasses the evaporator 14 and returns to the compressor 11.

[0021] The compressed air dehumidifier of the present invention is equipped with a proportional control solenoid valve 22 that is connected to a portion of the lubricant return pipe 20 that is piped so as to be located midway below the refrigerant inlet 14a of the evaporator and is arranged to adjust the flow rate of the return lubricant oil, and a control device 60 that controls the proportional control solenoid valve 22.

[0022] In the compressed air dehumidifier of the present invention, when the lubricating oil circulating in the refrigerant from the compressor 11 of the refrigeration cycle is returned to the compressor 11 through the lubricating oil return pipe 20, bypassing the evaporator 14, the lubricating oil can be returned more appropriately to the compressor 11 by the action of the lubricating oil return pipe 20 arranged in an appropriate position and the proportional control solenoid valve 22, thereby achieving the particularly advantageous effect of enabling operation with good responsiveness even under high load conditions.

[0023] That is, the upstream side of the lubricant return pipe 20 is connected to the refrigerant pipe 15 between the expansion valve 13 and the refrigerant inlet 14a of the evaporator, and the proportional control solenoid valve 22 connected to the lubricant return pipe 20 is arranged to be located below the refrigerant inlet 14a of the evaporator. Therefore, the piping configuration from the lubricant return pipe 20 (upstream return pipe 21) upstream of the proportional control solenoid valve 22 through the refrigerant pipe 15 to the refrigerant inlet 14a of the evaporator and the lower part of the evaporator 14 is arranged substantially above the height position of the proportional control solenoid valve 22, and the volume from the refrigerant inlet 14a of the evaporator to the proportional control solenoid valve 22 can be smaller than the configuration of the invention described in Patent Document 1, for example.

[0024] According to this, the upstream flow path section for the return lubricant, which is composed of the lower part of the evaporator 14 and the lubricant return piping 20 (upstream return piping 21) upstream of the proportional control solenoid valve 22 from the refrigerant inlet 14a of the evaporator through the refrigerant piping 15, is located substantially above the height position of the proportional control solenoid valve 22, so that the return lubricant is likely to be suitably retained upstream of the proportional control solenoid valve 22 due to gravity, and the return lubricant can flow smoothly due to the pressure of the refrigerant when the proportional control solenoid valve 22 opens.

[0025] In this way, the connection between the proportional control solenoid valve 22 and the upstream flow passage section of the return lubricant oil allows the return lubricant oil to flow smoothly, and the proportional control solenoid valve 22 allows appropriate control to return the accumulated lubricant oil (return lubricant oil) to the compressor 11 with good responsiveness when the refrigeration cycle device 10 is determined to be in a high load state. For example, the load state is determined by the discharge pipe temperature sensor 16, the high pressure sensor 17, and the dew point sensor 34 described later, and the opening of the proportional control solenoid valve 22 is controlled according to the load state, and the rotation speed of the compressor 11 (control of the electric motor M1) is controlled by the inverter to ensure the dew point performance, while the oil level of the lubricant oil in the compressor 11 can be controlled to be maintained within a normal range.

[0026] That is, the return lubricant oil returned from the evaporator 14 of the refrigeration cycle device 10 configured as a plate-type heat exchanger to the compressor 11 is not simply controlled to be returned during high load, but can be returned as needed without affecting the dew point, so that the return amount can be stabilized and the responsiveness can be improved. Also, by understanding the state of the refrigeration cycle device 10 from the degree of change in the dew point and the current value (rotation speed) of the compressor 11, the required amount of oil (return lubricant oil) can be returned in a timely manner.

[0027] In addition, since the solenoid valve installed in the conventional lubricant return pipe is ON / OFF open / close controlled, when it is opened, the return lubricant flows suddenly, and the refrigerant also flows in a bypass, causing a sudden change in the dew point. In contrast, in the present invention, the proportional control solenoid valve 22 can prevent a sudden change in the dew point, and the accumulated lubricant (return lubricant) can be returned to the compressor 11 with good responsiveness as described above.

[0028] In this embodiment, the volume of the flow passage of the lubricant return pipe 20 is set to be smaller than the volume of the flow passage of the refrigerant return pipe 15a. This allows the amount of retained lubricant (return lubricant) to be reduced, so that the return lubricant can be returned to the compressor 11 with good responsiveness, and the oil level (required oil amount) of the lubricant in the compressor 11 can be more appropriately maintained. If the part of the refrigerant pipe 15, which is the section of the pipe through which the return lubricant is returned from the evaporator 14 to the proportional control solenoid valve 22, and the upstream return pipe 21 are shortened as much as possible and connected to the proportional control solenoid valve 22, the amount of return lubricant can be substantially reduced, so that it can be returned to the compressor 11 more effectively.

[0029] In this embodiment, a capillary tube 23 for regulating the flow of return lubricant oil returned to the compressor 11 is connected to the middle of the lubricant oil return pipe 20. This makes it possible to restrict the flow of return lubricant oil, and therefore to restrict the flow of refrigerant that is bypassed by the flow of return lubricant oil, thereby preventing abrupt dew point fluctuations.

[0030] Furthermore, in this embodiment, the capillary tube 23 is connected to the downstream side (downstream return pipe 24 side) of the flow of return lubricant oil, which is closer to the compressor 11 than the portion of the lubricant return pipe 20 to which the proportional control solenoid valve 22 is connected. With this, the position of the capillary tube 23 is opposite to the side that is close to the evaporator 14 and is easily cooled on the upstream side (upstream return pipe 21 side) of the flow of return lubricant oil from the proportional control solenoid valve 22, across the proportional control solenoid valve 22, so that the flow of the capillary tube 23 can be easily ensured, and a more stable device configuration can be achieved.

[0031] In this embodiment, at least one of the following sensors is provided: a discharge pipe temperature sensor 16 for measuring the refrigerant temperature at the refrigerant outlet side of the compressor 11, a high pressure sensor 17 for measuring the refrigerant pressure at the refrigerant outlet side of the condenser 12, and a dew point sensor 34 for measuring the dew point of the secondary compressed air dehumidified by heat exchange by the evaporator 14 in the dehumidifier housing 30. A control device 60 is connected to the at least one sensor and determines the load state of the refrigeration cycle device 10 based on the detection information of the at least one sensor and controls the proportional control solenoid valve 22 according to the load state. The control device 60 is also provided to control the operation of the refrigeration cycle device 10 by controlling the electric motor M1 of the compressor 11 and the electric motor M2 of the condenser cooling fan 12a of the condenser 12, in addition to controlling the proportional control solenoid valve 22.

[0032] According to this, the load condition is determined using the discharge pipe temperature sensor 16, the high pressure sensor 17, and the dew point sensor 34 based on data from individual detection results or data derived from a combination of multiple detection results, and the opening of the proportional control solenoid valve 22 is controlled according to the load condition, so that the oil level of the lubricating oil in the compressor 11 can be suitably controlled while ensuring dew point performance by controlling the rotation speed of the compressor 11 (electric motor control) using an inverter.

[0033] For example, when the discharge pipe temperature sensor 16 detects that the refrigerant temperature is higher than the set temperature (when the load state is determined), the proportional control solenoid valve 22 is opened and adjusted in accordance with the degree of the detection, so that the return lubricant oil is returned to the compressor 11. Also, when the high pressure sensor 17 detects that the refrigerant pressure (condensation pressure) is higher than the set pressure (when the load state is determined), the proportional control solenoid valve 22 is opened and adjusted in accordance with the degree of the detection, so that the return lubricant oil is returned to the compressor 11. Also, when the dew point sensor 34 (temperature sensor) detects that the compressed air temperature (dew point) is higher than the set temperature (when the load state is determined), the proportional control solenoid valve 22 is opened and adjusted in accordance with the degree of the detection, so that the return lubricant oil is returned to the compressor 11. Then, in contrast to the above-mentioned state, if it is determined that the load is low, then the proportional control solenoid valve 22 may be controlled to perform the opposite operation to that performed when the load is high, such as by adjusting the opening of the proportional control solenoid valve 22 to close it.

[0034] As an example of the embodiment according to the present invention, the upstream return pipe 21, which is the pipe upstream of the proportional control solenoid valve 22 of the lubricant return pipe 20 in the flow of return lubricant, may be configured to be insulated by a heat insulating material. This allows the upstream return pipe 21 to be insulated from the outside air, and the occurrence of condensation can be prevented.

[0035] As an example of the embodiment according to the present invention, the downstream return pipe 24, which is a pipe downstream of the proportional control solenoid valve 22 of the lubricant return pipe 20 in the flow of the return lubricant, may be arranged in a position where it is heated by the exhaust heat of the refrigeration cycle device 10. For example, the downstream return pipe 24 may be arranged near the inlet pipe of the condenser 12. This allows the return lubricant to be appropriately heated and the fluidity of the return lubricant to be increased, thereby improving the response of the control of the flow of the return lubricant and stabilizing the amount of return lubricant to the compressor 11.

[0036] In this embodiment, as shown in FIG. 2, a dehumidifier housing 30 is provided as the main body of a heat exchanger unit 50 so as to dehumidify primary compressed air (see black arrow in FIG. 2) introduced from an air compressor (compressed air source) such as an air compressor by heat exchange and discharge (supply) the dehumidified secondary compressed air (see open arrow in FIG. 2). Inside the dehumidifier housing 30, a heat exchanger (a plate-type heat exchanger) is provided in two stages, a first heat exchanger section 33 and a second heat exchanger section 40.

[0037] The first heat exchanger section 33 is provided by arranging a pre-cooling flow path 33a for the primary compressed air and a re-heating flow path 33b for the secondary compressed air so as to intersect with each other so as to pre-cool the primary compressed air and re-heat the secondary compressed air, and the second heat exchanger section 40 is provided so as to cool the compressed air pre-cooled by the first heat exchanger section 33 with an evaporator 14 to cause condensation and dehumidify the air. This allows the primary compressed air to be rationally and efficiently cooled and dehumidified, and the secondary compressed air to be suitably reheated and discharged.

[0038] In this embodiment, the second heat exchanger section 40 is arranged to introduce primary-side compressed air from above and discharge secondary-side compressed air to the below, and is equipped with a secondary-side communication passage 55 that communicates the secondary-side compressed air from the second heat exchanger section 40 to the first heat exchanger section 33, a gas-liquid separation flow passage section 45 that is a space below the second heat exchanger section 40 and allows drain water 70 generated by condensation to drip and accumulate at the bottom, and is formed to communicate the secondary-side compressed air to the secondary-side communication passage 55, a drain discharge port 35 that is provided to discharge drain water to the lower end of the gas-liquid separation flow passage section 45 or the secondary-side communication passage 55, and a temperature sensor 34 (see Figure 1) with a sensing section that detects temperature, located in an upper portion of the space of the gas-liquid separation flow passage section 45 where the drain water 70 does not accumulate.

[0039] The temperature sensor 34 in this embodiment is configured such that the sensing unit is disposed in a space (flow path space) at the lower part (bottom) inside the dehumidifier housing 30, where the compressed air is cooled by a cooling medium (cold water or refrigerant flowing through the evaporator 14) in the second heat exchanger unit 40 and the temperature is at its lowest. Note that the drain discharge port 35 is connected to, for example, a drain discharge circuit device (not shown), which is a component connected to a control valve 36 of the drain discharge device. As the drain discharge circuit device, for example, a drain treatment machine including a gas-liquid separation tank and an adsorption treatment tank (oil-water separator) is connected.

[0040] In addition, in this embodiment, the first heat exchanger section 33 and the second heat exchanger section 40 are arranged at one end side 51 and the other end side 52 in the horizontal direction of the dehumidifier housing 30, the first heat exchanger section 33 is arranged to communicate the primary side compressed air from the lower side to the upper side and the secondary side compressed air from the upper side to the lower side, and the secondary side communication passage 55 is provided in the horizontal intermediate part of the dehumidifier housing 30 between the first heat exchanger section 33 and the second heat exchanger section 40 and is arranged to communicate the secondary side compressed air from the lower side to the upper side.

[0041] 2, the first heat exchanger section 33 and the second heat exchanger section 40 are plate-type heat exchangers, and are continuously connected to form a heat exchanger unit 50. This allows the compressed air dehumidifier to be configured in a compact and simple form. In addition, the heat exchanger unit 50 has a box-like shape, making it possible to efficiently utilize the installation space.

[0042] Next, a flow of compressed air within the dehumidifier housing 30 of the embodiment shown in FIG. 2 will be described. The compressed air inlet 31 and the compressed air outlet 32 ​​are provided at the lower part of the one end wall part 51a forming the end face of the one end side 51 of the dehumidifier housing 30, which is the side where the first heat exchanger part 33 is arranged. In addition, the second heat exchanger part inlet 40a is provided at the upper part of the secondary side communication passage 55, which communicates the primary side compressed air from the pre-cooling flow passage 33a of the first heat exchanger part 33 to the second heat exchanger part 40. In addition, the gas-liquid separation flow passage part 45 and the secondary side communication passage 55 are connected by the secondary side communication passage inlet 55a. In addition, the secondary side communication passage 55 is provided at the upper part of the secondary side communication passage 55 with the secondary side communication passage outlet 55b, which communicates the secondary side compressed air from the secondary side communication passage 55 to the reheating flow passage 33b of the first heat exchanger part 33.

[0043] According to this, primary side compressed air is introduced from the air compressor to the first heat exchanger section 33 through the compressed air inlet 31, and is introduced from the first heat exchanger section 33 to the second heat exchanger section 40 through the second heat exchanger section inlet 40a. The secondary side compressed air generated by passing through the second heat exchanger section 40 is communicated to the secondary side communication passage 55 through the secondary side communication passage inlet 55a, and communicated to the first heat exchanger section 33 through the secondary side communication passage outlet 55b. The compressed air in this embodiment flows from bottom to top in the pre-cooling flow passage 33a of the first heat exchanger section 33, flows from top to bottom in the cooled flow passage 42 of the second heat exchanger section 40, flows from bottom to top in the secondary side communication passage 55, and flows from top to bottom in the reheating flow passage 33b of the first heat exchanger section 33.

[0044] The other end wall portion 52a forms the end face of the other end side 52 of the dehumidifier housing 30, which is the side where the second heat exchanger portion 40 is arranged, and an inlet (refrigerant inlet 14a of the evaporator) for the cooling medium (refrigerant) in the second heat exchanger portion 40 is provided at the lower part thereof, and an outlet (refrigerant outlet 14b of the evaporator) for the cooling medium (refrigerant) in the second heat exchanger portion 40 is provided at the upper part thereof. A refrigerant is supplied to the inlet (refrigerant inlet 14a of the evaporator) from a refrigerant supply source (for example, the expansion valve 13 of the refrigeration cycle device 10 shown in FIG. 1). In this second heat exchanger portion 40, as shown by the gray arrow in FIG. 2, the refrigerant flows from the lower side to the upper side, and the refrigerant flow path 41 and the cooled flow path 42 are provided so as to intersect with each other, so that the compressed air flowing into the cooled flow path 42 of the second heat exchanger portion 40 is cooled, and moisture in the compressed air is condensed. The compressed air flowing through the cooled flow path 42 becomes a downward flow, which is the same direction as the direction of gravity. Therefore, the drain water 70 generated by condensation can be smoothly swept away and discharged / dried in the direction of the gas-liquid separation flow path section 45, where it can be collected.

[0045] In the compressed air dehumidifier of this embodiment, an air flow sensor 38 and an air pressure sensor 39 are disposed at the compressed air inlet 31 into which the compressed air on the primary side of the dehumidifier housing 30 is introduced. The control device 60 controls the proportional control solenoid valve 22 as described above, and determines the load state of the refrigeration cycle device based on the detection information of the flow rate and pressure of the compressed air on the primary side detected by the air flow sensor 38 and the air pressure sensor 39, and controls the operation of the compressor 11 and the condenser cooling fan 12a, which is a component of the condenser 12, according to the load state. Reference numeral 12b denotes a heat dissipation fin.

[0046] Although the present invention has been described above in various preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. [Explanation of symbols]

[0047] 10 Refrigeration cycle equipment 11 Compressor 12 Condenser 12a Condenser cooling fan 12b Heat sink fin 13 Expansion valve 14 Evaporator 14a Refrigerant inlet of evaporator 14b Refrigerant outlet of evaporator 15 Refrigerant piping 15a Refrigerant return pipe 16 Discharge pipe temperature sensor 17 High pressure sensor 20 Lubricant return pipe 21 Upstream return pipe 22 Proportional control solenoid valve 23 Capillary tube 24 Downstream return pipe 30 Dehumidifier housing 31 Compressed air inlet 32 Compressed air outlet 33 First heat exchanger section 33a Pre-cooling channel 33b Reheat channel 34 Dew point sensor 35 Drain outlet 36 Drain discharge device control valve 38 Air flow sensor 39 Air pressure sensor 40 Second heat exchanger section 40a Second heat exchanger section inlet 41 Coolant flow path 42 Cooled channel 45 Gas-liquid separation channel section 50 Heat Exchanger Unit 51 One end 51a One end wall 52 Other end side 52a Other end wall 55 Secondary side communication path 55a Secondary communication passage inlet 55b Secondary side communication passage outlet 60 Control device 70 Drain water

Claims

1. A compressed air dehumidifier comprising a refrigeration cycle device provided with a compressor, a condenser, an expansion valve, and an evaporator, and a dehumidifier housing in which the evaporator of the refrigeration cycle device is installed so as to cool compressed air introduced from an air compressor and dehumidify the compressed air by condensing moisture in the air, the evaporator being formed integrally with the dehumidifier housing as a plate-type heat exchanger, a refrigerant inlet for introducing refrigerant is provided below the evaporator, and a refrigerant outlet for discharging refrigerant is provided above the evaporator, a lubricant return pipe, the upstream side of which is connected to a refrigerant pipe between the expansion valve and the refrigerant inlet of the evaporator, and the downstream side of which is connected to a refrigerant return pipe which is a refrigerant pipe between the refrigerant outlet of the evaporator and the compressor, so that return lubricant oil returned to the compressor bypasses the evaporator; a proportional control solenoid valve connected to a portion of the lubricant return pipe that is located midway through the lubricant return pipe and is positioned below the refrigerant inlet of the evaporator, and arranged to adjust the flow rate of the return lubricant; and a control device for controlling the proportional control solenoid valve.

2. 2. The compressed air dehumidifier according to claim 1, wherein the volume of the flow passage of the lubricant return pipe is smaller than the volume of the flow passage of the refrigerant return pipe.

3. 2. The compressed air dehumidifier according to claim 1, further comprising a capillary tube connected to a midway point of the lubricant return pipe for regulating the flow of the return lubricant returned to the compressor.

4. 4. The compressed air dehumidifier according to claim 3, wherein the capillary tube is connected to a downstream side of the flow of the return lubricating oil on the compressor side relative to a portion of the lubricating oil return pipe to which the proportional control solenoid valve is connected.

5. At least one of a discharge pipe temperature sensor that measures a refrigerant temperature on a refrigerant outlet side of the compressor, a high-pressure pressure sensor that measures a refrigerant pressure on a refrigerant outlet side of the condenser, and a dew point sensor that measures a dew point of the secondary compressed air that has been dehumidified by heat exchange by the evaporator in the dehumidifier housing, 2. The compressed air dehumidifier according to claim 1, wherein the at least one sensor is connected to the control device which determines a load state of the refrigeration cycle device based on detection information from the at least one sensor and controls the proportional control solenoid valve in accordance with the load state.

6. 2. The compressed air dehumidifier according to claim 1, wherein an upstream return pipe, which is a pipe upstream of the proportional control solenoid valve in the flow of the return lubricating oil of the lubricating oil return pipe, is insulated with a heat insulating material.

7. 2. The compressed air dehumidifier according to claim 1, wherein a downstream return pipe, which is a pipe downstream of the proportional control solenoid valve in the flow of the return lubricating oil of the lubricating oil return pipe, is arranged in a position where it is heated by exhaust heat from a refrigeration cycle device.

8. The compressed air dehumidifier according to any one of claims 1 to 7, characterized in that the dehumidifier housing is provided to dehumidify primary-side compressed air introduced from an air compressor by heat exchange and discharge the dehumidified secondary-side compressed air, a heat exchanger is provided inside the dehumidifier housing in two stages, a first heat exchanger unit and a second heat exchanger unit, the first heat exchanger unit is provided by arranging a pre-cooling flow path for the primary-side compressed air and a reheating flow path for the secondary-side compressed air so as to intersect with each other so as to pre-cool the primary-side compressed air and reheat the secondary-side compressed air, and the second heat exchanger unit is provided to cool the compressed air pre-cooled in the first heat exchanger unit with the evaporator to cause condensation and dehumidify it.

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