Compressed air dehumidifier and control method thereof

Abstract

To provide a compressed air dehumidifier and a control method thereof, which enable control of switching to a more optimal operation state in accordance with an operation load state.SOLUTION: In a compressed air dehumidifier, compressed air on a primary side introduced from an air compressor is dehumidified by heat exchange; a dehumidifier casing 30 is provided to discharge dehumidified compressed air on a secondary side; a flow channel (e.g., an evaporator 14) for circulating a cooling medium is disposed inside the dehumidifier casing 30; and an air flow sensor 38 and an air pressure sensor 39 are disposed at a compressed air inlet 31 to which the primary side compressed air of the dehumidifier casing 30 is introduced. The compressed air dehumidifier comprises a control device 60 that determines a load state of a device (e.g., a refrigeration cycle device 10) for circulating the cooling medium on the basis of detection information for a flow rate and pressure related to the primary side compressed air detected by the air flow sensor 38 and the air pressure sensor 39 to control operation of the device for circulating the cooling medium according to the load state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a compressed air dehumidifier in which a dehumidifier housing is provided to dehumidify primary compressed air introduced from an air compressor through heat exchange and discharge the dehumidified secondary compressed air, and a flow path for circulating a cooling medium is arranged inside the dehumidifier housing so as to dehumidify the compressed air by cooling the compressed air and condensing the moisture in the compressed air, and a control method thereof. [Background technology]

[0002] In conventional dryers (compressed air dehumidifiers) equipped with a compressor driven by an electric motor at a constant speed of refrigeration cycle equipment, the rotation speed cannot be controlled even if the load state changes, so the dryer always operates at a constant power and 100% capacity, and there is a possibility of freezing when there is no load or low load in a low temperature environment. Also, because the dryer always operates at 100% capacity even under conditions of low pressure and increased airflow, a large amount of drain water is generated, and when the flow velocity is high, the drain water is easily carried away.

[0003] In contrast, an example of a conventional compressed air dehumidifier has been proposed by the present applicant, which includes a heat exchanger that cools compressed air introduced from a gas inlet in an evaporator in a refrigeration cycle, dehumidifies the air by condensing the moisture in the compressed air, and discharges it from a gas outlet, a refrigerant compressor that compresses a refrigerant to cool the evaporator, a dehumidification load measuring means (temperature sensor and control unit) that measures the dehumidification load on the compressed air to be dehumidified, and a control unit that controls the operating state of the refrigerant compressor based on the measurement result of the dehumidification load measuring means, and when the measurement result of the dehumidification load measuring means is below a predetermined load amount, the control unit controls the refrigerant compressor to either intermittent operation or stopped operation for at least a predetermined time period (see Patent Document 1).

[0004] Furthermore, the present applicant has proposed an example of a compressed air dehumidifier equipped with a conventional plate-type heat exchanger, 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 which executes a "first process" (see Patent Document 2) in which, when the control unit detects a predetermined high-load state, it controls the solenoid valve to increase the flow rate of fluid moving through the lubricating oil discharge pipe.

[0005] The present applicant has also proposed a conventional vertical cylindrical compressed air dehumidifier in which a heat exchanger is provided in two stages, a first heat exchanger section and a second heat exchanger section, the two heat exchanger sections being arranged vertically next to each other and built into an outer wall cylindrical main body, the first small chamber being located below the two heat exchanger sections, into which the air outlet of the second heat exchanger section and the inlet of the reheating flow path are opened, the first small chamber being provided with a drain section at its lower end, a second small chamber being located above the two heat exchanger sections and for retaining the compressed air immediately before it is discharged, an extended air vent section being extended downward so that the air outlet of the second heat exchanger section is located below the inlet of the reheating flow path, and a demister being disposed at the lower end within the extended air vent section and through which the compressed air passes (see Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-246336 A (Page 1) [Patent Document 2] JP 2014-124565 A (Page 1) [Patent Document 3] JP 2017-127801 A (Page 1) Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved regarding compressed air dehumidifiers and control methods thereof is that, although conventionally, as in Patent Document 1, a temperature sensor has been primarily provided as a dehumidification load measuring means, there has been no proposal regarding a compressed air dehumidifier and control method thereof that can grasp the operating load state of the compressed air dehumidifier by combining with other sensors and control switching to a more optimal operating state in accordance with that operating load state.

[0008] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a compressed air dehumidifier and a control method thereof that are capable of controlling switching to a more optimal operating state in accordance with the operating load state. [Means for solving the problem]

[0009] 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 dehumidifier housing is provided to dehumidify primary compressed air introduced from an air compressor by heat exchange and to discharge the dehumidified secondary compressed air, and a flow path for circulating a cooling medium is arranged inside the dehumidifier housing so as to cool the compressed air and dehumidify the moisture in the compressed air by condensing it, in the compressed air dehumidifier, an air flow sensor and an air pressure sensor are disposed at a compressed air inlet into which the primary compressed air of the dehumidifier housing is introduced, and a control device is provided which determines the load state of a device that circulates the cooling medium based on detection information of the flow rate and pressure of the primary compressed air detected by the air flow sensor and the air pressure sensor, and controls the operation of the device that circulates the cooling medium in accordance with the load state.

[0010] Furthermore, in one embodiment of the compressed air dehumidifier according to 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 to dehumidify the primary side compressed air introduced from the air compressor by heat exchange and discharge the dehumidified secondary side compressed air, and the evaporator of the refrigeration cycle device is installed inside the dehumidifier housing so as to cool the compressed air and condense the moisture in the compressed air to dehumidify it. In this compressed air dehumidifier, an air flow sensor and an air pressure sensor are disposed at a compressed air inlet into which the primary side compressed air of the dehumidifier housing is introduced, and a control device is provided which determines the load state of the refrigeration cycle device based on detection information of the flow rate and pressure related to the primary side compressed air detected by the air flow sensor and the air pressure sensor, and controls the operation of the compressor and the operation of a condenser cooling fan, which is a component of the condenser, according to the load state.

[0011] In addition, according to one aspect of the compressed air dehumidifier of the present invention, the operation control may be performed by inverter control.

[0012] Furthermore, according to one embodiment of the compressed air dehumidifier of the present invention, a heat exchanger is provided inside the dehumidifier housing in two stages, a first heat exchanger section and a second heat exchanger section, the first heat exchanger section 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 section is provided to cool the compressed air pre-cooled in the first heat exchanger section using the evaporator to cause condensation and dehumidify the compressed air.

[0013] In addition, according to one aspect of the compressed air dehumidifier of the present invention, the evaporator is a plate type heat exchanger.

[0014] In addition, according to one example of a control method for a compressed air dehumidifier of the present invention, there is provided a control method for switching operation modes in response to changes in the flow rate and pressure of the primary side compressed air introduced using the compressed air dehumidifier described above, and the control method can include a first judgment step of determining whether the flow rate is equal to or less than a certain percentage of the rated load and the pressure is maintained at or below a certain level, a first switching step of determining that the load is no load or low load and switching operation to a low load mode if a positive judgment is made in the first judgment step, a second judgment step of determining whether the flow rate is equal to or more than the rated load and the pressure is maintained at or below a certain level if a negative judgment is made in the first judgment step, a second switching step of determining that the load is a low pressure increased air load and switching operation to a roll-up prevention mode which is a mode for reducing the generation of drain water, which is a collection of condensation of moisture, if a negative judgment is made in the second judgment step, and an operation maintenance step of maintaining normal operation if a negative judgment is made in the second judgment step. Effect of the Invention

[0015] The compressed air dehumidifier and the control method thereof according to the present invention have a particularly advantageous effect of enabling control to switch to a more optimal operating state in accordance with the operating load state. [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. 4 is a flowchart showing an example of a method for controlling a compressed air dehumidifier according to the present invention. [Diagram 3] FIG. 1 is a schematic diagram showing an example of an embodiment in which a refrigeration cycle device is provided in addition to a 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 to 3).

[0018] In the compressed air dehumidifier according to the present invention, as a basic configuration, a dehumidifier housing 30 is provided to dehumidify the primary compressed air introduced from an air compressor by heat exchange and discharge the dehumidified secondary compressed air, and a flow path for circulating a cooling medium is arranged inside the dehumidifier housing 30 so that the compressed air is cooled and the moisture in the compressed air is dehumidified by condensing it. Examples of the flow path for circulating the cooling medium include a flow path for circulating a refrigerant for a refrigeration cycle as described later, and a flow path for cold water introduced from a cold water source such as a chiller device or groundwater.

[0019] Alternatively, in the compressed air dehumidifier of the present invention, as a basic configuration, a refrigeration cycle device 10 equipped with a compressor 11, a condenser 12, an expansion valve 13 and an evaporator 14 is provided, and a dehumidifier housing 30 is provided to dehumidify the primary compressed air introduced from the air compressor by heat exchange and discharge the dehumidified secondary compressed air, and the evaporator 14 of the refrigeration cycle device 10 is installed inside the dehumidifier housing 30 so as to dehumidify the compressed air by cooling it and condensing the moisture in the compressed air.

[0020] In the compressed air dehumidifier of the present invention, an air flow sensor 38 and an air pressure sensor 39 are disposed at the compressed air inlet 31, through which the primary side compressed air of the dehumidifier housing 30 is introduced, so as to measure the flow rate and pressure of the primary side compressed air.

[0021] The compressed air dehumidifier according to the present invention is also provided with a control device 60 that determines the load state of the device that circulates the cooling medium based on the detection information of the flow rate and pressure of the primary compressed air detected by the air flow sensor 38 and the air pressure sensor 39, and controls the operation of the device that circulates the cooling medium according to the load state. Examples of the device that circulates the cooling medium include a refrigeration cycle device that circulates a refrigerant for a refrigeration cycle as described below, a chiller device equipped with a pump function that can supply cold water while adjusting the flow rate, and a cold water supply device that supplies cold water from a cold water source such as groundwater.

[0022] Alternatively, the compressed air dehumidifier according to the present invention includes a control device that determines the load state of the refrigeration cycle device 10 based on the detection information of the flow rate and pressure of the compressed air on the primary side detected by the air flow rate 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. Note that 12b is a heat dissipation fin. Also, the control device 60 can control the proportional control solenoid valve 22 as described later.

[0023] The compressed air dehumidifier according to the present invention has a special advantageous effect of being able to control switching to a more optimal operating state in accordance with the operating load state. That is, according to the compressed air dehumidifier according to the present invention, when the pressure of the compressed air (compressed air on the primary side) introduced into the dehumidifier housing 30 drops and the flow rate increases, the air flow sensor 38 and the air pressure sensor 39 arranged in the compressed air inlet 31 determine that the operating state is in a low-pressure increased air state and switch the operating state to an operating control that suppresses the take-out of drain water (for example, control that reduces the rotation speed of the compressor 11 and the condenser cooling fan 12a and reduces the dehumidification capacity), and when it determines that the no-load or low-load state has been reached, it is possible to switch to anti-freeze and energy-saving operating control (for example, control that sets the rotation speed of the compressor 11 and the condenser cooling fan 12a to the minimum rotation speed and does not reduce the refrigerant temperature), thereby enabling more optimal operation in accordance with the operating load state.

[0024] In addition, in this embodiment, the above-mentioned operation control is characterized by being performed by inverter control, which allows stepless control of the operation of the compressor 11 (control of the rotation speed of the electric motor) and the operation of the condenser cooling fan 12a, which is a component of the condenser 12 (control of the rotation speed of the electric motor), and allows control to switch to a more accurate and optimal operation state according to the operating load state.

[0025] Furthermore, in this embodiment, the evaporator 14 is a plate-type heat exchanger, which will be described in detail below.

[0026] In this embodiment, as shown in FIG. 1, 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. 1) introduced from an air compressor (compressed air source) such as an air compressor by heat exchange, and to discharge (supply) the dehumidified secondary compressed air (see open arrow in FIG. 1). Inside the dehumidifier housing 30, a heat exchanger (plate-type heat exchanger) is provided in two stages, a first heat exchanger section 33 and a second heat exchanger section 40.

[0027] 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.

[0028] 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 3) 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.

[0029] The temperature sensor 34 in this embodiment is configured such that the sensing unit is disposed in a lower portion (bottom) inside the dehumidifier housing 30, in a space (flow path space) where the compressed air is cooled by a cooling medium (cold water or a 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 the control valve 36 of the drain discharge device 36. 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.

[0030] 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.

[0031] In the embodiment shown in Fig. 1, both the first heat exchanger section 33 and the second heat exchanger section 40 are plate-type heat exchangers, and the two are continuously connected to form the heat exchanger unit 50. This allows the compressed air dehumidifier to be configured in a compact and simple form. In addition, since the heat exchanger unit 50 has a box shape, the device form allows efficient use of the installation space.

[0032] Next, a flow of compressed air within the dehumidifier housing 30 of the embodiment shown in FIG. 1 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.

[0033] 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.

[0034] 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. 3). In the second heat exchanger portion 40, the refrigerant flows from the lower side to the upper side as shown by the gray arrow in FIG. 1, and the refrigerant flow path 41 and the cooled flow path 42 are arranged 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 the 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 and dripped in the direction of the gas-liquid separation flow path section 45, where it can be collected.

[0035] Next, a control method for a compressed air dehumidifier according to the present invention will be described with reference to Fig. 2. This control method uses the above-mentioned compressed air dehumidifier to switch the operation mode in response to changes in the flow rate and pressure of the primary side compressed air introduced, and can be characterized by including the following judgment and switching processes (steps). As shown in the flowchart of Fig. 2, when the dryer (compressed air dehumidifier) ​​starts operating, compressed air flows into the dryer, and then the process proceeds to a step of switching the operation state in response to the flow rate and pressure (constant judgment), and the following judgment and switching steps are executed.

[0036] First, in a first judgment step 100, it is judged whether the flow rate is equal to or less than a certain percentage of the rated load and the pressure is maintained at or below a certain level. That is, in the first judgment step 100, the control device judges whether the flow rate of compressed air measured by the air flow sensor 38 is equal to or less than a certain percentage of the rated load and the pressure of compressed air measured by the air pressure sensor 39 is maintained at or below a certain level. Note that the flow rate being equal to or less than a certain percentage of the rated load can be, for example, 20 to 40% of the rated flow rate. As a specific example, when the rated flow rate is 5 m 3 / min, 1~2m 3 / min. A constant compressed air pressure can be, for example, 70-80% of the normal pressure. As a specific example, if the normal pressure is 0.7 MPa, the pressure will be 0.49-0.56 MPa. Furthermore, the compressed air pressure can be determined by integrating the pressure fluctuation within a certain period of time, in addition to monitoring a constant value. In this case, erroneous determinations due to momentary pressure fluctuations can be eliminated, allowing for more accurate determinations.

[0037] Next, in the first switching step 200, if the first judgment step 100 is judged to be affirmative, it is judged that the load is no load or low load, and the operation is switched to the low load mode. That is, in the first switching step 200, if the control device 60 judges that the flow rate of compressed air measured by the air flow sensor 38 is equal to or lower than a certain percentage of the rated load and the pressure of compressed air measured by the air pressure sensor 39 is maintained at or below a certain level, the control device 60 judges that the load is no load or low load, and controls to switch the operation to the low load mode. Note that this low load mode can be, for example, an operation mode in which the rotation speed of the compressor 11 and the condenser cooling fan 12a is set to the minimum rotation speed, and the refrigerant temperature is controlled not to decrease (the target dew point is changed) to prevent freezing and enable energy-saving operation.

[0038] Next, in a second judgment step 300, it is judged whether or not the flow rate is equal to or greater than the rated load and the pressure is maintained at or below a certain level when a negative judgment is made in the first judgment step 100. That is, in the second judgment step 300, the control device 60 judges whether or not the flow rate of compressed air measured by the air flow sensor 38 is equal to or greater than the rated load and the pressure of compressed air measured by the air pressure sensor 39 is maintained at or below a certain level.

[0039] Next, in the second switching step 400, if the second judgment step 300 is positive, the load is judged to be a low pressure air increase load, and the operation is controlled to switch to the roll-up prevention mode, which is a mode for reducing the generation of drain water, which is a collection of condensation of moisture. That is, in the second switching step 400, if the control device 60 judges that the flow rate of compressed air measured by the air flow sensor 38 is equal to or higher than the rated load and the pressure of compressed air measured by the air pressure sensor 39 is maintained at a constant level or lower, the control device 60 judges that the load is a low pressure air increase load, and controls to switch to the roll-up prevention mode, which is a mode for reducing the generation of drain water, which is a collection of condensation of moisture. Note that the roll-up prevention mode can be, for example, an operation mode for reducing the amount of drain water generated by controlling the dehumidification capacity to be reduced (changing the target dew point) by reducing the rotation speed of the compressor 11 and the condenser cooling fan 12a, thereby suppressing the take-out of drain water at low pressure.

[0040] Then, in the operation maintaining step 500, control is performed to maintain normal operation if a negative determination is made in the second judgment step 300. That is, in the operation maintaining step 500, control is performed to maintain normal operation if the control device 60 determines that the flow rate of compressed air measured by the air flow sensor 38 is not less than the rated load and that the pressure of compressed air measured by the air pressure sensor 39 is not maintained at a constant level or less.

[0041] As described above, this provides the particularly advantageous effect of enabling control to be performed to switch to a more optimal operating state in accordance with the operating load state.

[0042] Next, with reference to FIG. 3, a description will be given of an embodiment in which the embodiment in FIG. 1 is combined with a refrigeration cycle device 10 to form a compressed air dehumidification device.

[0043] In the compressed air dehumidifier of this embodiment, as a basic configuration, a refrigeration cycle device 10 equipped with a compressor 11, a condenser 12, an expansion valve 13 and an evaporator 14 is provided, and a dehumidifier housing 30 is provided 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.

[0044] 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.

[0045] In addition, in this embodiment, a lubricating oil return pipe 20 is provided, which is connected at its upstream side to the refrigerant pipe 15 between the expansion valve 13 and the refrigerant inlet 14a of the evaporator, and at its downstream side to the refrigerant return pipe 15a, which is the refrigerant pipe 15 between the refrigerant outlet 14b of the evaporator and the compressor 11, thereby bypassing the evaporator 14 and returning the return lubricating oil to the compressor 11 to the compressor 11.

[0046] In this embodiment, the system 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, and a control device 60 that controls the proportional control solenoid valve 22.

[0047] According to the compressed air dehumidifier of this embodiment, 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, resulting in the particularly advantageous effect of being able to operate with good responsiveness even under high load conditions.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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 of the return lubricant oil flow (upstream return pipe 21 side) of 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.

[0056] In this embodiment, at least one of the discharge pipe temperature sensor 16 for measuring the refrigerant temperature at the refrigerant outlet side of the compressor 11, the high pressure sensor 17 for measuring the refrigerant pressure at the refrigerant outlet side of the condenser 12, and the 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 is provided, and a control device 60 for determining the load state of the refrigeration cycle device 10 based on the detection information of the at least one sensor and controlling the proportional control solenoid valve 22 according to the load state is connected to the at least one sensor. The control device 60 is provided to control not only the proportional control solenoid valve 22 but also the electric motor M1 of the compressor 11 and the electric motor M2 of the condenser cooling fan 12a of the condenser 12, thereby controlling the operation of the refrigeration cycle device 10.

[0057] 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 appropriately controlled while ensuring dew point performance by controlling the rotation speed of the compressor 11 and the condenser cooling fan 12a (electric motor control) using an inverter.

[0058] 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.

[0059] In addition, as an example of this embodiment, the upstream return pipe 21, which is a pipe upstream of the proportional control solenoid valve 22 of the lubricant return pipe 20 in the flow of the return lubricant, can be configured to be insulated by a heat insulating material. According to this, the upstream return pipe 21 is insulated from the outside air, and the occurrence of condensation can be prevented.

[0060] As an example of this embodiment, 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.

[0061] 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]

[0062] 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 100 First decision step 200 First Switching Step 300 Second Judgment Step 400 Second switching step 500 Operation Maintenance Steps

Claims

1. A compressed air dehumidifier is provided with a dehumidifier housing for dehumidifying primary compressed air introduced from an air compressor by heat exchange and discharging the dehumidified secondary compressed air, and a flow path for circulating a cooling medium is disposed inside the dehumidifier housing so as to dehumidify the compressed air by cooling the compressed air and condensing moisture in the compressed air, an air flow rate sensor and an air pressure sensor are disposed at a compressed air inlet into which compressed air is introduced on the primary side of the dehumidifier housing; A compressed air dehumidifier comprising a control device that determines a load state of a device that circulates a cooling medium based on detection information of the flow rate and pressure of the primary side compressed air detected by the air flow sensor and the air pressure sensor, and controls the operation of the device that circulates the cooling medium in accordance with the load state.

2. A compressed air dehumidifier is provided with a refrigeration cycle device having a compressor, a condenser, an expansion valve, and an evaporator, a dehumidifier housing is provided to dehumidify primary compressed air introduced from the air compressor by heat exchange, and the dehumidified secondary compressed air is discharged, and the evaporator of the refrigeration cycle device is installed inside the dehumidifier housing so as to dehumidify the compressed air by cooling the compressed air and condensing the moisture in the compressed air, an air flow rate sensor and an air pressure sensor are disposed at a compressed air inlet into which compressed air is introduced on the primary side of the dehumidifier housing; A compressed air dehumidifier comprising a control device that determines a load state of a refrigeration cycle device based on detection information of the flow rate and pressure of the primary side compressed air detected by the air flow sensor and the air pressure sensor, and controls the operation of the compressor and the condenser cooling fan, which is a component of the condenser, according to the load state.

3. 3. The compressed air dehumidifier according to claim 2, wherein the operation is controlled by inverter control.

4. The compressed air dehumidifier of claim 3, characterized in that a heat exchanger is provided inside the dehumidifier housing in two stages, a first heat exchanger section and a second heat exchanger section, the first heat exchanger section 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, and the second heat exchanger section is provided to cool the compressed air pre-cooled in the first heat exchanger section using the evaporator to cause condensation and dehumidify the compressed air.

5. 5. A compressed air dehumidifier according to claim 4, wherein the evaporator is a plate type heat exchanger.

6. A control method for switching an operation mode according to a change in flow rate and pressure of the primary compressed air introduced using the compressed air dehumidifier according to any one of claims 1 to 5, a first determination step of determining whether the flow rate is maintained at or below a certain percentage of the rated load and the pressure is maintained at or below a certain level; a first switching step of determining that the load is no load or low load when a positive determination is made in the first determination step and switching the operation to a low load mode; a second determination step of determining whether or not the flow rate is equal to or greater than the rated load and the pressure is maintained at or below a certain level when a negative determination is made in the first determination step; a second switching step of determining that the load is a low pressure air boost load and switching the operation to a roll-up prevention mode, which is a mode for reducing the generation of drain water, which is a collection of condensation of moisture, when a positive determination is made in the second determination step; and an operation maintaining step of maintaining normal operation when a negative determination is made in the second determination step.

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