JPH06129719A - Dehumidifying device for compressed gas - Google Patents

Abstract

PURPOSE:To eliminate the damage and the like of a driving motor and a pressure switch for a cooling fan and carry out stabale operation throughout an year by a method wherein a pressure sensor, detecting a refrigerant pressure at the downstream of a compressor for a refrigerating cycle, and a control means, controlling the number of rotation of the cooling fan in accordance with the detected refrigerant pressure, are equipped. CONSTITUTION:A compressor 2 is cooled by cooling air from a cooling fan 10 while a refrigerant pressure is detected by a pressure sensor 16 at the downstream of the compressor 2 for a refrigerating cycle. A setter 19 for setting an objective refrigerant pressure is provided and the objective refrigerant pressure, set by the setter 19, is compared with the detected refrigerant pressure of the pressure sensor 16 while a frequency commanding signal is outputted to an inverter device 13 based on PID operation with respect to a pressure difference between both pressures. According to this method, the frequency of AC power, supplied to a driving motor 11 by the inverter device 13, is controlled whereby the variable speed operation of the cooling fan 10 can be effected steplessly within a wide range with a good efficiency and gas can be cooled and compressed well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a dehumidifier for compressed gas.

[0002]

2. Description of the Related Art Compressed air produced by an air compressor contains a large amount of moisture at high temperature. Therefore, the moisture is removed by a dehumidifier, which causes dew condensation in the piping system of the compressed air and adverse effects on air equipment. Need to be prevented. As the dehumidifying device, there are a chemical drying system and a freeze drying system. In the freeze drying system, a refrigeration cycle is constituted by a refrigerant compressor, a condenser, an evaporator, etc., and an evaporator is provided in a heat exchanger. The high temperature compressed air supplied into the heat exchanger is cooled by the evaporator, and the moisture in the compressed air is removed.

Further, in the above dehumidifying device, in order to cool and condense the refrigerant well in the condenser, a cooling fan that sends cooling air to the condenser is provided, and a pressure switch is provided at a location downstream of the condenser in the refrigeration cycle. It is equipped. Then, when the refrigerant pressure at the downstream portion becomes equal to or higher than the set value, the pressure switch is turned on, the cooling fan is operated, and when the refrigerant pressure becomes equal to or lower than the set value, the pressure switch is turned off and the cooling fan is turned on. Be stopped.

[0004]

By the way, when the temperature is high such as in summer, the cooling fan must be frequently driven to rotate in order to cool and condense the refrigerant well by the condenser. The operation / stop and the pressure switch on / off are frequently repeated. By the way, a large starting current flows through the drive motor of the cooling fan at the time of startup.
When the stop is frequently repeated, a large starting current frequently flows to the drive motor of the cooling fan, which causes a problem that the drive motor is damaged.

Further, there has been a problem that the contacts of the pressure switch are damaged due to the frequent on / off of the pressure switch. As described above, the conventional freeze-drying dehumidifier has a problem such as damage to the drive motor of the cooling fan and the pressure switch when the temperature is high, such as in the summer, so stable operation cannot be performed throughout the year. That was the reality. An object of the present invention is to provide a dehumidifier for compressed gas that can solve the above problems.

[0006]

To achieve the above object, the present invention is characterized in that a refrigerating cycle is constituted by a refrigerant compressor, a condenser, an evaporator, etc., and cooling air is supplied to the condenser. A cooling fan for sending is provided, and an evaporator is provided in the heat exchanger, and the high temperature compressed gas supplied into the heat exchanger is cooled by the evaporator to remove water in the compressed gas. The point is that a pressure sensor that detects the refrigerant pressure is provided downstream of the condenser of the refrigeration cycle, and a control unit that controls the rotation speed of the cooling fan in accordance with the detected refrigerant pressure. In some cases, an inverter device for supplying AC power to the drive motor of the cooling fan is provided, and the control means controls the inverter device to frequency control the AC power.

[0007]

The high-temperature and high-pressure refrigerant sent from the refrigerant compressor is cooled and condensed in the condenser, expanded and evaporated in the evaporator, and cools in the heat exchanger. In the heat exchanger, the hot compressed gas is cooled by the evaporator, which
Moisture contained in the compressed gas is condensed on the surface of the evaporator or the like, and separated and removed from the compressed gas.

In the above case, the condenser is cooled by receiving the cooling air from the cooling fan, and the pressure of the refrigerant is detected by the pressure sensor downstream of the condenser of the refrigeration cycle. Then, depending on the detected refrigerant pressure,
The rotation speed of the cooling fan is controlled. That is, the higher the detected refrigerant pressure, the higher the rotational speed of the cooling fan, and the lower the detected refrigerant pressure, the lower the rotational speed of the cooling fan.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a dehumidifier of a compressed air refrigeration system.
The refrigerant compressor 1, the condenser 2, the dryer 3, the strainer 4, the evaporator 5 composed of a capillary tube, the strainer 6, and the accumulator 7 are connected in a loop, and the refrigerant outlet side pipe line of the refrigerant compressor 1 and the accumulator 7 are connected.
And are connected via a capacity control valve 8 to form a refrigeration cycle. The capacity control valve 8 keeps the inlet side refrigerant pressure and the outlet side refrigerant pressure of the refrigerant compressor 1 constant.
Controlled. Further, as the refrigerant, for example, CFC gas is used.

A cooling fan 10 sends cooling air to the condenser 2 and is driven to rotate by a drive motor 11. An inverter device 13 rectifies the alternating current from the commercial alternating-current power supply 14 and then converts the alternating current into a three-phase alternating current of a desired frequency to supply power to the drive motor 11 to rotate the cooling fan 10 depending on the magnitude of the frequency. Control the number steplessly. For example, at a frequency of 20 Hz, the rotation speed of the cooling fan 10 is 60
The rotation speed of the cooling fan 10 is 1800 c / m at 0 c / m and a frequency of 60 Hz. Reference numeral 16 is a pressure sensor, which detects the refrigerant pressure immediately after the condenser 2 of the refrigeration cycle, and an electric signal (4 mA to 20 mA) according to the pressure change.
Is output.

Reference numeral 18 denotes an adjuster of the inverter device 13, which has a setting device 19 for setting a target refrigerant pressure, and the target refrigerant pressure and pressure sensor 16 set by the setting device 19.
The detected refrigerant pressure is compared to the frequency command signal (DC (1 to 1
5V)) is output to the inverter device 13. Reference numeral 21 denotes a heat exchanger, which communicates with a pre-cooling chamber 22 that pre-cools the high-temperature compressed air from the air compressor, a cooling chamber 23 that includes the evaporator 5 and that cools the pre-cooled compressed air, and a cooling chamber 23. It comprises a storage chamber 24 and a warming chamber 25 which is contained in the pre-cooling chamber 22 and in which the compressed air from the storage chamber 24 is heated.

Reference numeral 27 denotes an auto drain trap, which is a cooling chamber 2
Water and impurities such as oil remaining inside 3 are automatically discharged to the outside. According to the embodiment configured as described above, a part of the high-temperature and high-pressure refrigerant sent from the refrigerant compressor 1 is sent to the accumulator 7 via the capacity control valve 8 and the rest is taken to the condenser 2. , Cooled and condensed. The refrigerant condensed and cooled is dried by the dryer 3,
It is sent to the evaporator 5 via the strainer 4, and the evaporator 5
Then, after undergoing expansion and evaporation while performing a flow rate limiting action by the capillary tube and performing a cooling action in the heat exchanger 21, it returns to the refrigerant compressor 1 via the strainer 6 and the accumulator 7.

In the heat exchanger 21, the high temperature compressed air sent from the air compressor exchanges heat with the cooled compressed air in the precooling chamber 22, and after being precooled, it is cooled in the cooling chamber 23.
Finally, it is rapidly cooled to about 10 ° C. by the evaporator 5. As a result, the water contained in the compressed air is condensed on the surface of the evaporator 5 and the like, and is separated and removed from the compressed air. The compressed air from which the water has been removed enters the warming chamber 25 via the storage chamber 24, exchanges heat with the high-temperature compressed air passing through the precooling chamber 22, is heated, and has extremely high relative humidity. Externally supplied as low dry air.

In the above case, the condenser 2 is cooled by receiving the cooling air from the cooling fan 10 and the refrigerant pressure is detected by the pressure sensor 16 downstream of the condenser 2 in the refrigeration cycle. . Then, the controller 18 controls the target refrigerant pressure by the setter 19 and the pressure sensor 16
Is compared with the detected refrigerant pressure and the frequency command signal is output to the inverter device 13 based on the PID operation for the pressure deviation between the two.

As a result, the AC power supplied from the inverter device 13 to the drive motor 11 is frequency-controlled, and the cooling fan 10 is operated in a wide range efficiently and steplessly at a variable speed. That is, as the detected refrigerant pressure becomes higher than the target refrigerant pressure, the frequency is increased and the rotation speed of the cooling fan 10 is increased, and as the detected refrigerant pressure becomes lower than the target refrigerant pressure, the frequency is decreased. As a result, the rotation speed of the cooling fan 10 is reduced. By the above control, the condenser 2
Thus, good cooling and condensation of the refrigerant is performed. The example is
Although the present invention is applied to a dehumidifier for compressed air,
INDUSTRIAL APPLICABILITY The present invention can be applied to a dehumidifying device for compressed gas other than compressed air.

[0016]

As described in detail above, according to the present invention,
Since a pressure sensor that detects the refrigerant pressure downstream of the condenser of the refrigeration cycle and a control unit that controls the rotation speed of the cooling fan according to the detected refrigerant pressure are provided, the cooling fan is constantly driven to rotate. There is no fear that a large starting current will frequently flow to the drive motor of the cooling fan and damage the drive motor, etc., allowing stable operation of the dehumidifier throughout the year and cooling the condenser well at all times. it can. According to the second aspect, the cooling fan can be efficiently operated over a wide range in a stepless manner at a variable speed, and the condenser can be cooled even better.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Refrigerant compressor, 2 ... Condenser, 5 ... Evaporator, 10 ... Cooling fan, 11 ... Drive motor, 13 ... Inverter device, 1
6 ... Pressure sensor, 18 ... Regulator, 21 ... Heat exchanger.

Claims (2)

[Claims] 1. A refrigeration cycle is constituted by a refrigerant compressor, a condenser, an evaporator, etc., a cooling fan for sending cooling air to the condenser is provided, and an evaporator is provided for a heat exchanger,
A high-pressure compressed gas supplied into the heat exchanger is cooled by an evaporator to remove moisture in the compressed gas, and a pressure sensor that detects the refrigerant pressure downstream of the condenser of the refrigeration cycle, A dehumidifying device for compressed gas, comprising: a control unit that controls the rotation speed of a cooling fan according to the detected refrigerant pressure. 2. A dehumidification device for compressed air according to claim 1, further comprising an inverter device for supplying AC power to a drive motor of the cooling fan, and the control means controls the inverter device to frequency control the AC power. .