JP5820332B2 - Compression device - Google Patents

Description

  The present invention relates to a compression device including a dehumidifier.

  When air is compressed with a compressor, the temperature of the air rises. When the compressed air discharged from the compressor is supplied to the demand facility as it is through the pipe, the compressed air is cooled in the pipe, moisture in the compressed air is condensed, and so-called drain is generated in the pipe. If water is mixed in the pipe, the pipe and the demand equipment will be rusted, and the product produced by the demand equipment will be adversely affected. For example, in a food processing facility, compressed air may be sprayed onto a product. However, when air mixed with water is sprayed on food, a sanitary problem occurs.

  For this reason, generally, the compression apparatus which manufactures compressed air is provided with the dehumidifier (dryer) which removes a water | moisture content from compressed air, as described in patent document 1,2. As the dehumidifier for the compression device, one that cools the compressed air with a refrigeration device and condenses and separates moisture in the compressed air is usually used. When starting a compression apparatus equipped with such a dehumidifier, first the dehumidifier is started, and after the temperature of the flow path of the dehumidifier has sufficiently decreased, the operation of the compressor is started, so that moisture is supplied to the demand apparatus. Compressed air containing air should not be supplied.

  If the preceding operation time of such a dehumidifier is set short, when the outside air is hot and humid, etc., the compressor is started before exhibiting sufficient dehumidifying capacity, and compressed air is sent out without sufficient dehumidification. End up. The preceding operation time of the dehumidifier in a commercially available compression apparatus is set to about 3 minutes in consideration of safety. For this reason, the conventional compression apparatus may not be able to cope with a sudden increase in demand for compressed air.

Japanese Patent No. 3723459 JP 2009-56394 A

  In view of the above problems, an object of the present invention is to improve the reliability of a compression device.

The invention according to claim 1 is a compressor, which is a compressor capable of adjusting the discharge amount for compressing and discharging air, a dehumidifier for removing moisture from the compressed air discharged by the compressor, and the dehumidifying device. A supply flow path for supplying air to the demand facility with air removed from the machine, a dew point detector for directly or indirectly detecting the dew point of the compressed air after dehumidification by the dehumidifier, and a branch from the supply flow path. An exhaust passage that is opened to the atmosphere through a vent valve, a pressure detector that detects a pressure in the supply passage, and a control device that controls opening and closing of the vent valve, and When the dehumidifier is started while the compressed air discharged from the compressor is supplied, and the dew point of the compressed air flowing into the supply flow path from the dehumidifier is higher than a predetermined upper limit value, the air discharge valve is Open and discharge the compressed air to the atmosphere, dew point below the upper limit If it becomes, the compressed air is supplied to the demand facility closing said blow-off valve, wherein the control device, the pressure difference between the pressure and the atmosphere on the upstream side of the exhaust passage, and, of the exhaust passage Based on the cross-sectional area of the flow path, the discharge flow rate of the compressed air that can be discharged from the exhaust flow path is calculated, and the discharge flow rate of the compressed air discharged by the compressor when the compressed air is discharged from the exhaust flow path is calculated. The discharge flow rate is less than or equal to.

According to a second aspect of the invention, a compression apparatus according to claim 1, located downstream of the branch point of the exhaust flow path of the supply channel, from the exhaust passage of the compressed air And a stop valve that closes the supply flow path when discharging.

A third aspect of the present invention is the compression apparatus according to the second aspect , wherein the discharge flow rate of the compressed air discharged by the compressor when the compressed air is discharged is a discharge rate at a rated rotation of the compressor. Less than the flow rate.

A fourth aspect of the present invention is the compression apparatus according to any one of the first to third aspects, wherein the dew point detector is a dew point meter.

  According to the present invention, the reliability of the compression device can be improved.

It is a schematic block diagram of the compression apparatus of 1st Embodiment of this invention. It is a schematic block diagram of the compression apparatus of 2nd Embodiment of this invention.

  Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a compression apparatus 1 according to the first embodiment of the present invention. The compressor 1 sucks the air through the air filter 2, compresses and discharges the screw compressor 3, and cools the compressed air discharged by the screw compressor 3 to condense moisture in the compressed air. The dehumidifier 4 to be removed, the supply flow path 5 composed of the piping for supplying the compressed air from which the dehumidifier 4 has removed moisture to the demand facility, and branched from the supply flow path 5 and opened to the atmosphere via the air discharge valve 6 The exhaust flow path 7 is provided. The diameter of the piping of the exhaust passage 7 is smaller than that of the supply passage 5. The supply flow path 5 is provided with a check valve (not shown) to prevent air from flowing back from the demand facility to the supply flow path 5.

  A dew point detector 8 that is a dew point meter that detects the dew point of the compressed air after dehumidification, and a pressure detector 9 that detects the pressure of the compressed air are provided on the upstream side of the exhaust flow channel 7 of the supply flow channel 5. Is provided. The screw compressor 3 is driven by a motor 11 whose rotation speed is adjusted using an inverter 10, and the discharge flow rate is adjusted according to the rotation speed of the motor 11. The compression device 1 also has a control device 12 that controls the opening and closing of the air discharge valve 10 and sets the frequency of the inverter 10 based on the detection value of the dew point detector 8 and the detection value of the pressure detector 9. ing.

  When the compressor 1 is driven, the screw compressor 3 and the dehumidifier 4 are activated simultaneously. The dehumidifier 4 is supplied with compressed air discharged from the screw compressor 3. In addition, if compressed air is supplied at the time of starting of the dehumidifier 4, the screw compressor 3 and the dehumidifier 4 do not necessarily need to be started simultaneously. In the dehumidifier 4, the compressed air is dehumidified and the compressed air flows into the supply flow path 5. In practice, the compressed air is warmed after the dehumidification of the compressed air. In the control device 12, the dew point detector 8 detects the dew point of the compressed air flowing from the dehumidifier 4 into the supply flow path 5. When the dew point is higher than a preset upper limit value (for example, 10 ° C. under pressure), the control device 12 opens the air discharge valve 6. The control device 12 detects the pressure upstream of the exhaust flow path 7 detected by the pressure detector 9, that is, the pressure difference between the pressure in the supply flow path 5 and the atmosphere, and the flow path of the exhaust flow path 7. Based on the cross-sectional area, the discharge flow rate of the compressed air that can be discharged from the exhaust passage 7 to the atmosphere is calculated. In the control device 12, the frequency of the inverter 10 is adjusted so that the discharge flow rate of the compressed air discharged by the screw compressor 3 is equal to the discharge flow rate. Thereby, all the compressed air discharged from the screw compressor 3 is discharged | emitted from the exhaust flow path 7 to air | atmosphere. As a result, it is prevented that compressed air with high humidity is supplied to the demand facility.

  When the dew point of the dew point detector 8 is equal to or lower than the upper limit value, the air discharge valve 6 is closed, and compressed air is supplied to the demand facility through the supply flow path 5. At this time, the control device 12 is detected by the dew point detector 8 so that the dehumidifying load that increases as the discharge flow rate of the screw compressor 3 increases does not exceed the dehumidifying capacity of the dehumidifier 4, that is, the dew point detector 8. The set frequency of the inverter 10 is increased until the rotation speed reaches the rated rotation while controlling the increasing speed of the rotation speed of the screw compressor 3 so that the dew point does not exceed the upper limit again.

  As described above, the compression apparatus 1 according to the first embodiment has been described. However, in the compression apparatus that pre-cools the dehumidifier before the compressor is started, the dehumidifier is started in a state where compressed air does not flow. The dew point of the compressed air immediately after cannot be confirmed. As a result, wet compressed air may be supplied to the demand facility. Moreover, there exists a possibility that compressed air may be overcooled in a dehumidifier, and a water | moisture content will freeze. On the other hand, in the compressor 1, since the dehumidifier 4 starts in the state where compressed air flowed in, the dew point of compressed air can be confirmed. Furthermore, when the dew point is higher than the upper limit value, the compressed air is discharged from the exhaust passage 7, so that it is possible to prevent the wet compressed air from flowing into the demand facility. Since the pre-cooling of the dehumidifier 4 is not performed, the compressed air is prevented from being overcooled. Thus, in the compressor 1, since the compressed air with which the dew point was ensured can be supplied to a demand installation, reliability can be improved.

  In the compression device 1, when the compressed air is discharged from the exhaust flow path 7, the discharge flow rate of the compressed air discharged by the screw compressor 3 is made equal to the discharge flow rate that can be discharged in the exhaust flow path 7. As a result, compared with the case where the discharge flow rate of the screw compressor 3 is larger than the discharge flow rate, it is possible to efficiently discharge wet compressed air. In the compression device 1, the discharge flow rate of the screw compressor 3 may be less than the discharge flow rate. In this case, the control device 12 selects the set frequency of the inverter 10 so that the discharge flow rate of the screw compressor 3 is calculated to be equal to the value obtained by multiplying the discharge flow rate by a constant less than 1. Since the amount of compressed air supplied to the dehumidifier 4 is suppressed, the time required for the dew point to become the upper limit value or less can be shortened. As a result, it is possible to quickly supply compressed air to the demand facility.

  FIG. 2 shows a compression apparatus 1a according to the second embodiment of the present invention. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and duplicate descriptions are omitted. The supply flow path 5 of the present embodiment includes a stop valve 13 on the downstream side of the branch point with the exhaust flow path 7.

  When the compression device 1a is driven, if the detection value of the dew point detector 8 is higher than the upper limit value, the control device 12 opens the air discharge valve 6 and closes the stop valve 13. Thus, when the compressed air is discharged from the exhaust flow path 7, the stop valve 13 closes the supply flow path 5, so the discharge flow rate of the exhaust flow path 7 matches the discharge flow rate of the screw compressor 3. By closing the stop valve 13, the compressor 1a prevents the compressed air having a high dew point including a large amount of water from flowing to the demand equipment side and prevents the backflow of the compressed air from the demand equipment side, thereby reducing the loss. Reduced.

  The control device 12 sets the rotational speed of the screw compressor 3 to a preset rotational speed, for example, about 30 to 40% of the rated rotational speed until the detection value of the dew point detector 8 becomes lower than the upper limit value. Thereby, the discharge flow rate of the screw compressor 3 at the time of discharge of compressed air becomes smaller than the discharge flow rate at the time of rated rotation, and the amount of compressed air flowing into the dehumidifier 4 can be suppressed. As a result, the time required for the dew point to become the upper limit value or less can be shortened, and the supply of compressed air to the demand facility can be performed quickly.

  Also in 2nd Embodiment, since the compressed air with which the dew point was ensured can be supplied to a demand installation, the reliability of the compressor 1a can be improved. In the compressor 1a, the screw compressor 3 may be driven at the rated rotational speed as long as the compressed air can be discharged efficiently.

  In the second embodiment, a pressure detector may be provided on the supply flow path 5. When the pressure in the supply flow path 5 is low, when the screw compressor 3 and the dehumidifier 4 are started, the discharge valve 6 and the stop valve 13 are closed for several seconds to increase the pressure in the supply flow path 5 to a certain pressure. In the control device 12, the discharge flow rate is calculated based on the pressure difference between the pressure detected by the pressure detector and the atmosphere and the cross-sectional area of the exhaust flow channel 7. The compressed air is discharged from the exhaust passage 7 while controlling the screw compressor 3 so that the discharge flow rate and the discharge flow rate of the screw compressor 3 become equal. Thereby, the pressure in the supply flow path 5 can be maintained constant.

  As mentioned above, although embodiment of this invention was described, this invention can be variously changed. For example, the supply channel and the exhaust channel of the present invention may be configured in a dehumidifier package. In this case, a drain mechanism of a commercially available dehumidifier is used as the exhaust passage. In the present embodiment, a dehumidifier other than the cooling type may be used. A compressor other than a screw compressor may be used. Instead of the pressure detector 9, a flow meter may be provided.

  The dew point detector 8 may be provided in the dehumidifier 4. The dew point detector is not limited to a sensor that directly detects the dew point of the compressed air, but may be one that indirectly detects the dew point of the compressed air by detecting the temperature inside the dehumidifier or the pressure of the refrigerant. Further, the dew point detector is not limited to one that detects an analog value, and may output a digital value such as a switch that switches output at a constant dew point temperature or other corresponding value.

  Further, in the present invention, the discharge amount of the compressor may be adjusted by controlling the opening degree of the intake regulating valve in addition to the rotational speed control.

DESCRIPTION OF SYMBOLS 1, 1a ... Compression apparatus 2 ... Air filter 3 ... Screw compressor 4 ... Dehumidifier 5 ... Supply flow path 6 ... Air discharge valve 7 ... Exhaust flow path 8 ... Dew point detector 9 ... Pressure detector 10 ... Inverter 11 ... Motor 12 ... Control device 13 ... Stop valve

Claims (4)

A compressor capable of adjusting the discharge amount for compressing and discharging air; and
A dehumidifier that removes moisture from the compressed air discharged by the compressor;
A supply flow path for supplying air from which the dehumidifier has removed moisture to a demand facility;
A dew point detector for directly or indirectly detecting the dew point of the compressed air after dehumidification by the dehumidifier;
An exhaust passage that branches off from the supply passage and is opened to the atmosphere via a vent valve;
A control device for detecting the pressure in the supply flow path, and for controlling the opening and closing of the discharge valve;
With
When the dehumidifier is activated while compressed air discharged from the compressor is supplied, and the dew point of the compressed air flowing from the dehumidifier into the supply flow path is higher than a predetermined upper limit value, the air discharge valve To release the compressed air to the atmosphere, and when the dew point is less than or equal to the upper limit, close the vent valve and supply the compressed air to the demand equipment ,
The control device determines the discharge flow rate of the compressed air that can be discharged from the exhaust flow path based on the pressure difference between the pressure upstream of the exhaust flow path and the atmosphere and the cross-sectional area of the exhaust flow path. A compression device that calculates and discharges the compressed air discharged by the compressor when the compressed air is discharged from the exhaust flow path to be equal to or less than the discharge flow rate . The apparatus further comprises a stop valve that is located downstream of a branch point of the supply flow channel with the exhaust flow channel and closes the supply flow channel when compressed air is discharged from the exhaust flow channel. Item 2. The compression device according to Item 1. The compressor according to claim 2 , wherein a discharge flow rate of the compressed air discharged by the compressor when the compressed air is discharged is smaller than a discharge flow rate at the rated rotation of the compressor. The dew-point detector, the compression device according to any one of 3 claims 1, characterized in that a dew-point instrument.

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