JP2005046744A - Apparatus for dehumidifying compressed air - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive, sure method for automatically controlling the electromagnetic drain trap of a drain discharge apparatus by efficiently detecting a drain storage speed in an air compressor, especially in the cooler of an apparatus for dehumidifying compressed air. <P>SOLUTION: In the apparatus for dehumidifying compressed air having at least an inverter-controlled cooling medium compressor, a heat exchanger, and an apparatus for discharging drain in a compressed air supply path equipped with the electromagnetic drain trap, the actuation interval of the electromagnetic drain trap is changed over corresponding to the operation frequency of the cooling medium compressor. When the average of the operation frequency of the compressor during 45 seconds is 45-90 Hz, the operation interval of an electromagnetic valve is made 45 seconds. When the average is 0-44 Hz, the actuation interval of the electromagnetic valve is made 90 seconds. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technology for optimizing the operation of a drain discharge device having an electromagnetic drain trap in a drain discharge device for removing drain from a compressed air supply path of a compressed air device, particularly a compressed air dehumidifier.

  Since drain water generated in compressed air equipment causes various problems in use, it is known to provide a dehumidifier for compressed air and install a drain discharge device equipped with an electromagnetic drain trap in its cooler. The electromagnetic drain trap operates intermittently during the generation of compressed air, and discharges the drain water accumulated in the cooler to the drain processing unit using the compressed air from the main pipe.

  The amount of drain generated from the compressed air dehumidifier varies depending on various factors such as the flow rate of compressed air, the temperature of the intake air (atmosphere), and humidity. At this time, if the number of operation of the drain trap is less than the amount of drain generated, drain water will remain in the equipment and cause harm, so conventionally the operation time and operation interval of the drain trap were determined according to the maximum drain amount. . However, when the flow rate of compressed air decreases or the intake air temperature decreases, the number of operations is too many, and the pressure of the main pipe is consumed, resulting in loss of energy.

  In the drain discharge device of the dehumidifier that manually switches the operation interval of the drain trap to reduce the air loss, it is often necessary to perform a switching operation when there is a large fluctuation in a short time such as a difference in time every day. It was inconvenient in practice. On the other hand, the method of constantly monitoring the accumulation of drain with a level sensor or the like has drawbacks such as the possibility of failure and power consumption. Therefore, in order to provide a practical drain discharge device, it is an important problem how to detect the drain storage speed and at what timing to operate the drain trap.

The invention described in Japanese Patent Application Laid-Open No. 9-317994 proposes that the operation of the drain trap of the drain discharge device of the compressed air piping is linked to the load of the air compressor, and the specific means is based on the pressure in the compressed air tank. The operation of the air compressor is switched between the unloader system (output is controlled by opening and closing the valve) and the pressure switching system (output is controlled by the compressor switch). At the start of loading during unloader operation, ON during pressure switching operation Sometimes a method of operating the drain trap once is disclosed. In addition, when an increase in the drain amount is predicted from information from various sensors or the like, it is described that the drain discharge time per operation is changed. It also describes that when a drain trap is provided in the compressed air supply path of the dehumidifier, the drain discharge time per operation is changed by the measured value of a thermometer installed in the refrigerant pipe.
JP-A-9-317994

Next, the invention described in Japanese Patent Application Laid-Open No. 11-351497 is provided with an integration counter that integrates the operating time of the air compressor in the drain trap of the compressed air piping, and an electromagnetic drain trap every time the integration value reaches a certain value. Have been proposed, and a drain trap is operated periodically, and a drain discharge time per operation is increased or decreased according to the integrated value.
JP-A-11-351497

  In the case where the operation interval is interlocked with the load of the air compressor of the main pipe as in the inventions described in Patent Documents 1 and 2, the operation interval is ultimately determined according to the pressure in the compressed air tank, that is, the amount of compressed air used. Therefore, there is a possibility that the load of the air compressor and the amount of drain to be discharged are not necessarily linked, for example, even if the load of the air compressor is large due to the season or the weather, the actual amount of drain generation is small. Although it is also described that the drain discharge time per time is changed from the output of various sensors, manual switching is difficult to cope with fluctuations in a short time, while in the case of automatic, the control device is complicated. There is a problem of increasing costs.

  The present invention provides an inexpensive and reliable method for efficiently detecting the drain storage speed in the cooler of an air compression device, particularly a compressed air dehumidifier, and automatically controlling the electromagnetic drain trap of the drain discharge device. The purpose is to do.

  The invention according to claim 1 is a compressed air dehumidifying device having at least a refrigerant compressor, a heat exchanger, and a drain discharge device of a compressed air supply path provided with an electromagnetic drain trap. Accordingly, the above problem is solved by switching the operation interval of the electromagnetic drain trap. The air loss is reduced by automatically changing the operation interval of the solenoid valve according to the amount of dehumidified drain.

  While the output of the air compressor is generally controlled in accordance with the pressure in the compressed air tank or the like, that is, the amount of compressed air used, the output of the refrigerant compressor of the dehumidifier is generally a temperature sensor at the outlet of the heat exchanger and Since it is controlled by the output of the humidity sensor or the like, it is considered that the load of the refrigerant compressor better corresponds to the actual drain generation amount.

  That is, the cause of the increased drain generation amount is (1) an increase in the flow rate of compressed air, (2) an increase in the amount of water vapor contained in the intake air, (3) an increase in the amount of water droplets on the air flow, (4 ) An increase in the intake air temperature is conceivable, but only (1) is reflected in the control based on the amount of compressed air used, whereas all these factors can be reflected in the control based on the output of the refrigerant compressor. . Therefore, if the operation interval of the electromagnetic drain trap is switched in accordance with the load of the refrigerant compressor, automatic control of the drain discharge device is effectively performed with a simple configuration rather than simply controlling according to the amount of compressed air used. be able to.

  When the refrigerant compressor is an inverter type refrigerant compressor, the invention according to claim 2 solves the above problem by switching the operation interval of the electromagnetic drain trap according to the operating frequency of the inverter type refrigerant compressor. Resolve.

  In a refrigerant compressor equipped with an inverter, the amount of drain generated is estimated based on the output from a sensor such as the flow rate of compressed air, the intake air temperature, and humidity, and the number of revolutions of the motor is, for example, 0 to 90 Hz or 30 to 90 Hz. The operation frequency can be continuously varied, and the operation frequency can be output to another control device. In the dehumidifying apparatus of the present invention, the amount of drain generated by the operating frequency of the inverter compressor in the cooling circuit is approximately determined, and thereby the operation interval of the electromagnetic drain trap is switched.

  When the operation interval of the drain trap is switched discontinuously (two steps or three steps), the control can be simplified compared to the case where the operation is continuously changed. For example, when the average value of the operating frequency of the compressor in 45 seconds is 45 to 90 Hz, it is determined that the drain amount is large, and the operation interval of the solenoid valve is set to 45 seconds. When this average value is 0 to 44 Hz, the drain amount is judged to be small, and the operation interval of the solenoid valve is set to 90 seconds.

  Since the present invention efficiently detects the drain storage speed in the cooler of the air compressor, particularly the compressed air dehumidifier, as described above, it is inexpensive to automatically control the electromagnetic drain trap of the drain discharger. Can provide a reliable method.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of the configuration of an air compression device. In the figure, 1 is an air compressor, 2 is a compressed air tank, 3 is a dehumidifier, and 4 is a line filter. The air compressed by the air compressor 1 is temporarily stored in the compressed air tank 2 for pressure stabilization. However, since this compressed air contains a large amount of water vapor at a high temperature, it is necessary to remove water and oil by the dehumidifier 3. is there. The compressed air that has come out of the dehumidifying device 3 is further removed by the line filter 4 and then supplied to the user equipment. Depending on the type of the air compressor, the compressed air tank 2 may not be provided.

  FIG. 2 shows the internal structure of the dehumidifying device 3 of this embodiment. In the figure, 31 is a heat exchanger, 32 is an electromagnetic drain trap, 33 is a refrigerant compressor, 34 is a condenser, 35 is an electronic expansion valve, 38 is an accumulator, 39 is a capacity control valve, 40 is a control circuit, and 41 is a temperature. A sensor 42 is an inverter. The compressed air moistened with high temperature from the compressed air tank 2 enters the heat exchanger 31 from the air inlet, is cooled by exchanging heat with the refrigerant when passing between the fins inside, and discharged from the air outlet. At this time, the oil and water vapor are condensed and accumulated at the bottom of the heat exchanger 31 and are intermittently discharged to the drain treatment unit (not shown) by the electromagnetic drain trap 32.

  The refrigerant is first pressurized by the refrigerant compressor 33, condensed by fan cooling by the condenser 34, rapidly depressurized by the electronic expansion valve 35, evaporated inside the heat exchanger 31, and cools the compressed air by heat of vaporization. . The refrigerant discharged from the heat exchanger 31 is converted into a complete gas by the accumulator 38 and returned to the refrigerant compressor 33. The capacity control valve 39 adjusts the load of the refrigerant compressor 33 as necessary.

  The control circuit 40 is connected to the temperature sensor 41 provided in the heat exchanger 31, the inverter 42 of the refrigerant compressor 33, the capacity control valve 39, and the electromagnetic drain trap 32, and the temperature sensor 41, The control circuit 40, the electromagnetic drain trap 32, and a drain processing unit (not shown) constitute a drain discharge device of the compressed air dehumidifier of this embodiment.

  The control circuit 40 monitors the intake air temperature of the compressed air, controls the inverter 42 so that the temperature of the compressed air (dew point temperature) is below a predetermined temperature, and sets the operating frequency of the refrigerant compressor 33 to 0 (or 30) to While changing continuously between 90 Hz, the capacity | capacitance control valve 39 is opened and closed as needed. Then, the average value of the operating frequency of the refrigerant compressor 33 in a certain time (45 seconds) is calculated. When the operating frequency is 45 to 90 Hz, that is, when the drain amount is relatively large, the electromagnetic drain trap 32 is spaced at 45 second intervals. When the operation frequency of the refrigerant compressor 33 is 0 (or 30) to 44 Hz, that is, when the amount of drain is relatively small, the electromagnetic drain trap 32 is set at intervals of 90 seconds (operation frequency). Is small).

  Since the operating frequency of the compressor always changes and is unstable as a reference for switching the operation of the solenoid valve, in this embodiment, the operation is switched depending on the value of the operating frequency for a fixed time (45 seconds). In order to determine the amount of drainage, the operation frequency of the compressor is divided into two, and the determination is made based on which range the operation frequency is in. In one operation of the solenoid valve, the valve opening time is constant at 0.3 seconds. Therefore, when the operating frequency of the compressor is 45 Hz or higher, drain twice as much as when 44 Hz or lower is discharged. Become. This relationship is shown in FIG. The operation frequency of the compressor may be determined in three stages of 30 Hz or less, 31-60 Hz, 61-90 Hz, and the operation interval of the solenoid valve may be switched to three stages.

  In the present embodiment, the refrigerant compressor 33 is controlled by the inverter 42. However, in the control of the refrigerant compressor, a method (opening / closing method) of turning on / off the compressor according to the outlet temperature of the heat exchanger, A system (unloader system) that controls the load by opening and closing the air regulating valve may be used. In order to apply the present invention to these cooling methods, the operation interval of the electromagnetic drain trap is reduced during power ON or during load operation, and the operation interval is increased during power OFF or during unload operation. Good.

  The present invention proposes a simple control method for the drain trap by paying attention to the fact that the output of the refrigerant compressor of the dehumidifying device and the drain storage amount correspond well, and further uses a compressed air flow sensor, a humidity sensor, etc. Thus, the present invention can be similarly applied to a case where the refrigerant compressor is controlled. Moreover, the position of the drain trap is not limited to the dehumidifying device, and can be installed in other places.

The figure which shows an example of a structure of an air compression apparatus The figure which shows the internal structure of the dehumidification apparatus 3 of Example 1. FIG. The figure which shows the amount of drains in Example 1, an operation frequency, and operation | movement of a solenoid valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air compressor 2 Compressed air tank 3 Dehumidifier 4 Line filter 31 Heat exchanger 32 Electromagnetic drain trap 33 Refrigerant compressor 34 Condenser 35 Electronic expansion valve 38 Accumulator 39 Capacity control valve 40 Control circuit 41 Temperature sensor 42 Inverter

Claims (2)

Operation of an electromagnetic drain trap according to a load of a refrigerant compressor in a compressed air dehumidifying device having at least a refrigerant compressor, a heat exchanger, and a drain discharge device of a compressed air supply path provided with an electromagnetic drain trap A compressed air dehumidifying device characterized by switching the interval. A dehumidifying device for compressed air, wherein the refrigerant compressor is an inverter type refrigerant compressor, and the operation interval of the electromagnetic drain trap is switched in accordance with the operating frequency of the inverter type refrigerant compressor.