JP5268401B2 - Heat pump dryer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump type dryer assembly capable of carrying out energy-saving, capable of carrying out dehumidification of air with a low dew point by positively removing frost adhered to an evaporator and circulating the air to the evaporator, and capable of achieving efficient drying. <P>SOLUTION: The heat pump type dryer assembly is provided with a coolant line 10 connecting a compressor 5, a condenser 6, an expansion valve 7, and a first evaporator 8 or a second evaporator 9, an air line 11 connecting a blower 4, the condenser 6, a drying hopper 3, and the first evaporator 8 or the second evaporator 9, a three-way valve 31, a first opening and closing valve 29, a second opening and closing valve 30, and a CPU 50. The CPU 50 sets the three-way valve 31 in a second position so as to carry out change-over from the first evaporator 8 connected to the coolant line 10 to the second evaporator 9 not connected to the coolant line 10, and closes the first opening and closing valve 29 and opens the second opening and closing valve 30 so as to carry out change-over from the first evaporator 8 connected to the air line 11 to the second evaporator 9 not connected to the air line 11. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a heat pump drying apparatus, and more particularly to a heat pump drying apparatus that includes a heat pump unit and is used for drying a resin.

Conventionally, a drying apparatus including a heat pump unit including a refrigerant circuit to which a compressor, a radiator, a throttle mechanism, and an evaporator are connected is known. For example, a drying apparatus including a heat pump device in which a refrigerant circulates in the order of a compressor, a radiator, a throttle mechanism, a first evaporator, and a second evaporator has been proposed (see, for example, Patent Document 1).
JP 2005-16779 A

  The heat pump device of the drying apparatus proposed in Patent Document 1 can efficiently remove moisture in the air in drying such as clothes drying using the first evaporator and the second evaporator. On the other hand, when drying an object to be dried, for example, a resin before molding, with dry air having a low dew point less than 0 ° C., the dry air needs to be cooled to less than 0 ° C. In such a case, moisture in the air becomes frost and adheres to these evaporators. Then, since the frost adhering to these evaporators inhibits heat exchange with a refrigerant | coolant and air, it is necessary to remove the frost of these evaporators. In order to remove the frost in the evaporator, for example, by circulating the refrigerant in the reverse direction in the refrigerant circuit, the high-temperature and high-pressure gas refrigerant discharged from the compressor is supplied to the evaporator, and the frost applied by the heat It is tentative to remove. However, during such a defrosting operation, there is a problem in that drying must be interrupted and efficient drying cannot be achieved.

  The object of the present invention is to provide a heat pump type drying device that saves energy by applying a heat medium having high energy efficiency to the drying device, and also reliably removes frost adhering to the evaporator, An object of the present invention is to provide a heat pump type drying apparatus that can circulate air through an evaporator to dehumidify air having a low dew point and achieve efficient drying.

  In order to achieve the above object, a heat pump type drying apparatus of the present invention includes a heat pump unit including a compressor, a condenser, an expansion valve, and a plurality of evaporators, a drying tank in which resin is dried, and air in the drying tank. A heat medium line for connecting the compressor, the condenser, the expansion valve, and any of the evaporators, and circulating a heat medium, and the air blowing means, the condenser, An air line through which air is circulated, a heat medium switching means for switching the evaporator connected to the heat medium line, and the air line connected to the air line, connecting the drying tank and any of the evaporators An air switching means for switching the evaporator, and a control means for controlling the heat medium switching means and the air switching means, the control means being connected to the heat medium line. Any of the evaporators that controls the heat medium switching means and is connected to the air line so that the evaporator is switched to another evaporator that is not connected to the heat medium line. The air switching means is controlled to switch to another evaporator not connected to the air line.

  According to this heat pump type drying apparatus, when frost adheres to any evaporator connected to the heat medium line, the heat medium switching means is controlled by the control means, and any heat evaporation is performed in the heat medium line. The connection is switched from one evaporator to another. Further, the air switching means is controlled by the control means, and the connection is switched from an arbitrary evaporator to another evaporator in the air line.

Therefore, the supply of air containing a large amount of heat medium and moisture is stopped to any evaporator after switching. Therefore, further generation of frost can be prevented, and the temperature of an arbitrary evaporator rises due to heat transfer from the surroundings, so that frost adhering to the evaporator can be reliably removed.
On the other hand, air containing a large amount of heat medium and moisture is supplied to the other evaporators after switching. Therefore, the dehumidification of air can be continued from another evaporator by another evaporator.

As a result, it is possible to continue dehumidification of air while preventing further generation of frost and reliably removing frost attached to the evaporator. Therefore, it is possible to increase the drying efficiency of the resin by drying air with a low dew point while saving energy.
Further, in the heat pump type drying apparatus of the present invention, the evaporator is provided with temperature detection means for detecting the temperature of the evaporator, and the control means is based on temperature detection of the temperature detection means, It is preferable to control the heat medium switching unit and the air switching unit.

  According to this heat pump type drying apparatus, the control means controls the heat medium switching means and the air switching means based on the temperature detection by the temperature detection means at a predetermined temperature at which frost is generated. Therefore, since the heat medium switching means and the air switching means can be switched after detecting the generation of frost in the evaporator based on the temperature detection of the temperature detection means, the frost in the evaporator can be efficiently removed. it can.

Further, in the heat pump type drying apparatus of the present invention, the control means is provided with time measuring means for measuring a time for switching the heat medium switching means and the air switching means, and the control means is configured to measure the time measurement. It is preferable to control the heat medium switching means and the air switching means based on the time measurement of the means.
According to this heat pump type drying apparatus, the control means controls the heat medium switching means and the air switching means based on the time measurement of the time measurement means. Therefore, the heat medium switching means and the air switching means can be switched after detecting the occurrence of frost in the evaporator based on the time measurement for a predetermined time when the frost is generated. Can be removed easily and efficiently.

In the heat pump type drying apparatus of the present invention, it is preferable that the air line is provided with a supply unit for supplying air to the evaporator not connected to the air line.
According to this heat pump type drying apparatus, since air can be supplied to other evaporators not connected to the air line by the supply means, the temperature of the evaporator is raised, and frost adhering to the evaporator is effectively and effectively removed. It can be removed reliably.

Moreover, in the heat pump type drying apparatus of the present invention, it is preferable that the air supplied to the evaporator not connected to the air line is 5 to 95% with respect to the air circulating in the air line. is there.
According to this heat pump type drying apparatus, frost adhering to the evaporator can be removed more effectively and reliably.

In the heat pump type drying apparatus of the present invention, it is preferable that an evaporation side bypass for air to bypass the plurality of evaporators is provided in the air line.
When air is supplied to another evaporator not connected to the air line by the supply means to remove frost adhering to the evaporator, the air is excessively supplied to the other evaporator not connected to the air line. When water is supplied to water, water droplets generated by melting of frost may be mixed in the air and circulate through the air line again.

However, according to this heat pump-type drying device, air flows into the evaporation side bypass, and the air bypasses the evaporator, thereby preventing the circulation of air mixed with water droplets generated from frost. Air can be circulated.
Moreover, in the heat pump type drying apparatus of the present invention, it is preferable that heating means for heating air is connected to the air line on the upstream side of the drying tank and the downstream side of the condenser. .

In this heat pump type drying apparatus, the air flowing in the air line can be heated to a higher temperature by the heating means, and efficient drying of the resin requiring a high drying temperature can be achieved.
Moreover, in the heat pump type drying apparatus of the present invention, it is preferable that a removal means for removing volatile components is connected to the air line on the downstream side of the drying tank and the upstream side of the evaporator. is there.

In addition to water, the air supplied from the drying tank may contain a small amount of volatile components such as monomers and additives contained in the resin. As a result, the heat exchange rate may decrease.
However, in this heat pump type drying apparatus, the removal means can remove the volatile components and prevent the volatile components from adhering to the evaporator. Therefore, it is possible to prevent the heat exchange rate of the evaporator from decreasing and to circulate the low dew point air.

Moreover, in the heat pump type drying apparatus of the present invention, it is preferable that the air line is provided with a condensing side bypass for air to bypass the condenser.
According to this heat pump type drying apparatus, when the air in the drying hopper exceeds a predetermined temperature, the air flows into the condensing side bypass, and the air bypasses the condenser. Heating can be prevented.

Moreover, in the heat pump type drying apparatus of the present invention, it is preferable that the compressor boosts the heat medium in multiple stages.
According to this heat pump type drying apparatus, the heat medium can be efficiently compressed while reducing the burden on the compressor.

  According to the heat pump type drying apparatus of the present invention, it is possible to continue dehumidification of air while preventing further generation of frost and reliably removing frost adhering to the evaporator. Therefore, it is possible to increase the drying efficiency of the resin by drying air with a low dew point while saving energy.

FIG. 1 is an apparatus configuration diagram showing an embodiment of a heat pump type drying apparatus of the present invention.
The heat pump type drying apparatus 1 is configured as a drying system for dehumidifying and drying a resin (not shown) by using the heat pump unit 2 as a heat source and a cooling source.
It does not specifically limit as resin, For example, resin etc. which become a molding material used for a molding machine are used, The shape is preferably a granular form (pellet shape).

  This heat pump type drying apparatus 1 includes a heat pump unit 2, a drying hopper 3 as a drying tank, a blower 4 as a blowing means, and a heat medium (hereinafter, the heat medium may be referred to as “refrigerant”) line 10. The air line 11, the three-way valve 31 as the heat medium switching means, the first on-off valve 29 and the second on-off valve 30 as the air switching means, and the CPU 50 as the control means are provided.

The heat pump unit 2 is installed in the lower part of the heat pump type drying apparatus 1 and includes a compressor 5, a condenser 6, an expansion valve 7, a first evaporator 8 and a second evaporator 9.
The compressor 5 is provided in order to compress a refrigerant | coolant and to make a refrigerant | coolant into high temperature. The compressor 5 is connected to the CPU 50. As the compressor 5, for example, a reciprocating compressor, preferably a multi-stage boosting reciprocating compressor (specifically, a two-stage boosting reciprocating compressor) that boosts the refrigerant in multiple stages is used. If it is a multistage boost reciprocating compressor, the refrigerant can be efficiently compressed while reducing the load (torque) applied to the compressor 5.

The condenser 6 is provided to heat the blown air using a high-temperature refrigerant as a heat source. Specifically, the condenser 6 includes a heating source passage 21 through which a high-temperature refrigerant passes, and a blower-side passage 26 that is disposed to face the heating source passage 21 and through which blown air passes. In the condenser 6, heat is exchanged between the heating source passage 21 and the blower side passage 26.
The expansion valve 7 is provided to expand (depressurize) the refrigerant to lower the temperature of the refrigerant.

  The first evaporator 8 and the second evaporator 9 are provided to remove (dehumidify) moisture in the blown air using a low-temperature refrigerant as a cooling source, and have substantially the same device configuration. Moreover, the 1st evaporator 8 and the 2nd evaporator 9 are each arrange | positioned in parallel in the refrigerant | coolant line 10 and the air line 11 which are mentioned later. The first evaporator 8 includes a cooling-source-side first passage 19 through which a low-temperature refrigerant passes, and a dehumidification-side first passage 27 that is disposed opposite to the cooling-source-side first passage 19 and through which the blown air passes. ing. In the first evaporator 8, heat is exchanged between the cooling source side first passage 19 and the air side first passage 27.

Further, the first evaporator 8 is provided with a first temperature sensor 24 as temperature detecting means for measuring the temperature of the outer surface of the cooling source side first passage 19. The arrangement of the first temperature sensor 24 is not particularly limited. For example, the first temperature sensor 24 is arranged with an interval of 0.5 to 1.0 mm from the outer surface of the cooling source side first passage 19. The first temperature sensor 24 is connected to the CPU 50.
The second evaporator 9 includes a cooling-source-side second passage 20 through which a low-temperature refrigerant passes, and a dehumidification-side second passage 28 that is disposed opposite to the cooling-source-side second passage 20 and through which the blown air passes. It has. In the second evaporator 9, heat is exchanged between the cooling source side second passage 20 and the air side second passage 28.

Further, the second evaporator 9 is provided with a second temperature sensor 25 as temperature detecting means for measuring the temperature of the outer surface of the cooling source side second passage 20. The arrangement of the second temperature sensor 25 is not particularly limited. For example, the second temperature sensor 25 is arranged with an interval of 0.5 to 1.0 mm from the outer surface of the cooling source side second passage 20. The second temperature sensor 25 is connected to the CPU 50.
The refrigerant line 10 connects the compressor 5, the condenser 6, the expansion valve 7, and the first evaporator 8 or the second evaporator 9, and the refrigerant is circulated through the refrigerant line 10. ing.

The refrigerant is not particularly limited as long as it is a refrigerant used in a known heat pump. For example, carbon dioxide, for example, chlorofluorocarbons or other chlorofluorocarbons are used. Preferably carbon dioxide is used.
In the refrigerant line 10, the compressor 5, the condenser 6, the expansion valve 7, and the 1st evaporator 8 or the 2nd evaporator 9 are each connected by the following each line. That is, in the refrigerant line 10, the compressor 5 and the condenser 6 are connected by the first compression line 15A, and the condenser 6 and the expansion valve 7 are connected by the second compression line 15B. Further, in the refrigerant line 10, the expansion valve 7 and the first evaporator 8 or the second evaporator 9 are connected by the first pressure reducing line 16 </ b> A, and the first evaporator 8 or the second evaporator 9 and the compressor 5 are connected. Are connected by the second decompression line 16B.

The first decompression line 16A is connected to the expansion valve 7 on the upstream side, while the downstream side is branched into two branch lines (a decompression first branch line 17A and a decompression second branch line 18A), and the decompression first branch The cooling source side first passage 19 of the first evaporator 8 is connected to the line 17A, and the cooling source side second passage 20 of the second evaporator 9 is connected to the decompression second branch line 18A.
The second decompression line 16B is connected to the compressor 5 on the downstream side, while the upstream side is branched into two branch lines (a decompression third branch line 17B and a decompression fourth branch line 18B), and the decompression third branch line 17B. The cooling source side first passage 19 of the first evaporator 8 is connected to the first evaporator 8, and the cooling source side second passage 20 of the second evaporator 9 is connected to the decompression fourth branch line 18B. A three-way valve 31 is provided at a branch portion of the second decompression line 16B.

Thereby, the refrigerant line 10 is configured as a closed circuit of the heat pump unit 2.
The three-way valve 31 is provided to selectively switch the cooling source side first passage 19 or the cooling source side second passage 20 with respect to the refrigerant line 10.
The drying hopper 3 is installed on the upper side of the heat pump type drying apparatus 1, and the resin to be dried is temporarily stored.

In the drying hopper 3, the drying hopper 3 is arranged so as to face the drying hopper 3, and an air inlet 41 for ventilating the air (high-temperature dehumidified air) blown by the blower 4 to the drying hopper 3, An air outlet 42 is provided in the upper part and is used to allow the air after ventilation (air containing a large amount of moisture) to flow into the first evaporator 8 or the second evaporator 9.
In addition, the drying hopper 3 is supplied with a supply port (not shown) connected to a supply line for supplying resin from, for example, an aerodynamic transporter, and the lower part with a supply port for supplying a resin to a molding machine or the like. And a discharge port (not shown) to which a discharge line is connected. A third temperature sensor 45 is provided inside the drying hopper 3. The third temperature sensor 45 is connected to the CPU 50.

The blower 4 is installed beside the heat pump unit 2 (side portion. In FIG. 1, it is shown below the heat pump unit 2), and is provided to blow air to the drying hopper 3. .
The air line 11 connects the blower 4, the condenser 6, the drying hopper 3, and the first evaporator 8 or the second evaporator 9. Air is circulated through the air line 11. Yes.

  In the air line 11, the blower 4, the condenser 6, the drying hopper 3, and the first evaporator 8 or the second evaporator 9 are connected to each other by the following lines. That is, in the air line 11, the blower 4 and the condenser 6 are connected by the first heating line 23A, and the condenser 6 and the drying hopper 3 are connected by the second heating line 23B. Further, in the air line 11, the drying hopper 3 and the first evaporator 8 or the second evaporator 9 are connected by the first dehumidifying line 22A, and the first evaporator 8 or the second evaporator 9 and the blower 4 are connected. Are connected by the second dehumidification line 22B.

  The first heating line 23 </ b> A and the second heating line 23 </ b> B are provided with a third bypass 12 as a condensation side bypass for bypassing the air flowing into the condenser 6. That is, the third bypass 12 branches from the middle of the air flow direction of the first heating line 23A, and is connected to the middle of the air flow direction of the second heating line 23B. The third bypass 12 is provided with a third on-off valve 36. The third on-off valve 36 is connected to the CPU 50.

Further, the first dehumidification line 22A is connected to the drying hopper 3 on the upstream side, and the downstream side is branched into two branch lines (dehumidification first branch line 43A and dehumidification second branch line 44A) to dehumidify the first branch. The dehumidification side first passage 27 is connected to the line 43A, and the dehumidification side second passage 28 is connected to the dehumidification second branch line 44A.
Further, the second dehumidification line 22B is connected to the blower 4 on the downstream side, while the upstream side is branched into two branch lines (dehumidification third branch line 43B and dehumidification fourth branch line 44B), and the dehumidification third branch line. The dehumidifying side first passage 27 is connected to 43B, and the dehumidifying side second passage 28 is connected to the dehumidifying fourth branch line 44B.

  The first on-off valve 29 and the second on-off valve 30 are provided for switching between the first evaporator 8 and the second evaporator 9, and have substantially the same device configuration. Moreover, the 1st on-off valve 29 and the 2nd on-off valve 30 are each provided in the two branch lines of 22 A of 1st dehumidification lines. Specifically, the first on-off valve 29 is interposed in the middle of the air flow direction of the dehumidifying first branch line 43A. Moreover, the 2nd on-off valve 30 is interposed in the air flow direction middle of the dehumidification 2nd branch line 44A.

In addition, a first bypass 13 and a second bypass 14 as supply means are provided in the two branch lines of the first dehumidification line 22A, respectively.
The first bypass 13 is provided so that air bypasses the first on-off valve 29 in the dehumidifying first branch line 43 </ b> A. Specifically, the first bypass 13 branches from the upstream side of the dehumidification first branch line 43A to the first on-off valve 29 and is connected to the downstream side of the dehumidification first branch line 43A to the first on-off valve 29. . A first throttle valve 34 is provided midway in the air flow direction of the first bypass 13. The first throttle valve 34 is a flow rate adjustment valve that adjusts the flow rate of the air that passes through the first bypass 13 and is supplied to the first evaporator 8 depending on the opening degree.

  The second bypass 14 is provided so that air bypasses the second on-off valve 30 in the dehumidifying second branch line 44A. Specifically, the second bypass 14 branches from the upstream side of the dehumidifying second branch line 44A with respect to the second on-off valve 30, and is connected to the downstream side of the dehumidifying second branch line 44A with respect to the second on-off valve 30. . A second throttle valve 35 is provided midway in the air flow direction of the second bypass 14. The second throttle valve 35 is a flow rate adjusting valve that adjusts the flow rate of the air that passes through the second bypass 14 and is supplied to the second evaporator 9 depending on the opening degree.

The first dehumidifying line 22A has a first filter 51 and an oil separator 33 as a removing means interposed on the upstream side thereof.
That is, the first filter 51 is provided to remove dust contained in a small amount in the air supplied from the drying hopper 3. The oil separator 33 is provided to mainly remove a volatile component (oil component) contained in a small amount in the air supplied from the drying hopper 3. More specifically, it is disposed downstream of the first filter 51 and upstream of the branch portion of the first dehumidification line 22A. Moreover, as an oil separator, a filter type can be used, for example.

A second filter 52 is interposed on the downstream side of the second dehumidification line 22B.
That is, the second filter 52 is provided to remove a mist component contained in a small amount in the air supplied from the first evaporator 8 and the second evaporator 9.
Further, an auxiliary heater 32 as heating means indicated by a virtual line is interposed in the second heating line 23B as necessary. Specifically, the auxiliary heater 32 is provided to assist heating of the air in the blower-side passage 26 in the condenser 6, and is in the middle of the air flow direction of the second heating line 23 </ b> B and upstream of the drying hopper 3. And on the downstream side of the condenser 6.

Next, a method for drying the resin using the heat pump type drying apparatus 1 will be described.
In this heat pump type drying apparatus 1, a predetermined amount of resin is always supplied from a supply port to a drying hopper 3 via a supply line (not shown), and after staying for a predetermined time, is discharged from a discharge port (not shown) to a discharge line. .

  In this method, the compressor 5 and the blower 4 are activated. Before starting the compressor 5 and the blower 4, the three-way valve 31 is closed between the decompression fourth branch line 18B and the second decompression line 16B, and the decompression second branch line 17B and the second decompression line. It is set at a position (first position) where the space between 16B is opened. At the same time, the first on-off valve 29 is opened and the second on-off valve 30 is closed.

Further, the first throttle valve 34 and the second throttle valve 35 are also adjusted to a predetermined opening degree before starting the compressor 5 and the blower 4.
That is, when the first on-off valve 29 is opened and the second on-off valve 30 is closed, for example, 5 to 95%, preferably 5 to 80%, and more preferably with respect to the air flowing through the air line 11. The opening degree of the second throttle valve 35 is adjusted so that 5 to 20% of the air bypasses the second opening / closing valve 30 and passes through the second bypass 14.

On the other hand, when the second on-off valve 30 is opened and the first on-off valve 29 is closed, for example, 5 to 95%, preferably 10 to 80%, more preferably with respect to the air flowing through the air line 11, The opening degree of the first throttle valve 34 is adjusted so that 5 to 20% of the air bypasses the first opening / closing valve 29 and passes through the first bypass 13.
In the refrigerant line 10, the refrigerant is circulated by starting the compressor 5.

  That is, the compressor 5 compresses the refrigerant to heat the refrigerant, and the high temperature refrigerant reaches the condenser 6 via the first compression line 15A. In the condenser 6, the air in the blower side passage 26 is heated using the heating source passage 21 as a heating source. In addition, the temperature of the air heated in the condenser 6 is 120 degreeC or more (usually 160 degrees C or less), for example. Next, the refrigerant discharged from the condenser 6 reaches the expansion valve 7 via the second compression line 15B. Then, the refrigerant is expanded by the expansion valve 7 to cool the refrigerant.

  Next, the low-temperature refrigerant reaches the first evaporator 8 through the upstream side of the first decompression line 16A and the decompression first branch line 17A. In the first evaporator 8, the air in the dehumidification side first passage 27 is dehumidified using the cooling source side first passage 19 as a cooling source. The temperature of the dehumidified air is, for example, −20 ° C. or lower, specifically −40 to −20 ° C. Next, the refrigerant discharged from the dehumidifying side first passage 27 reaches the compressor 5 via the downstream side of the decompression third branch line 17B and the second decompression line 16B. Thus, the circulation of the refrigerant is continued in the refrigerant line 10 to which the first evaporator 8 is connected.

On the other hand, in the air line 11, air is circulated by the activation of the blower 4.
That is, the air blown by the blower 4 reaches the condenser 6 via the first heating line 23A. In the condenser 6, the air in the blower-side passage 26 is heated by the heating source passage 21, and then the high-temperature air discharged from the condenser 6 passes through the second heating line 23 </ b> B and the air inlet 41 to the drying hopper. 3 is introduced.

  Next, in the drying hopper 3, high-temperature air is blown onto the resin, and then air containing a large amount of moisture is discharged from the air outlet 42 to dry the resin. In this drying, the internal temperature of the drying hopper 3 is measured by the third temperature sensor 45. After that, the air containing a large amount of moisture reaches the middle of the first dehumidification line 22A (the branch portion between the dehumidification first branch line 43A and the dehumidification second branch line 44A).

The dust contained in a small amount in the air is connected to the first filter 51, and the oil component contained in the air in a small amount is removed by the oil separator 33.
And since the 1st on-off valve 29 is open | released, air reaches the dehumidification side 1st channel | path 27 of the 1st evaporator 8 via the dehumidification 1st branch line 43A. In the first evaporator 8, the air in the dehumidification-side first passage 27 is dehumidified by the cooling source-side first passage 19, and then the dehumidified air discharged from the first evaporator 8 is dehumidified in the second dehumidifier. It reaches the blower 4 via the branch line 43B and the downstream side of the second dehumidification line 22B. Thereby, in the air line 11 to which the first evaporator 8 is connected, air is circulated and the air is continuously dried.

Note that the mist component contained in the air in a small amount is removed by the second filter 52. While the first on-off valve 29 is opened and the second on-off valve 30 is closed, the second throttle valve 35 of the first bypass 14 is set to the above-described opening, so that a part of the air is The second bypass valve 30 is bypassed at a rate, passes through the second bypass 14, and is supplied to the second evaporator 9.
Further, in the first evaporator 8, the outer surface of the cooling source side first passage 19 is measured by the first temperature sensor 24 during dehumidification of air containing a large amount of moisture.

  When the temperature measured by the first temperature sensor 24 measures the temperature indicating that frost is attached to the outer surface of the cooling source side first passage 19, the three-way valve 31 is controlled by the CPU 50, In the refrigerant line 10, the connection of the cooling side first passage 19 of the first evaporator 8 is switched to the cooling side second passage 20 of the second evaporator 9. The temperature indicating that frost is attached to the outer surface of the cooling source side first passage 19 depends on the relative arrangement of the first temperature sensor 24 and the cooling source side first passage 19 in the first evaporator 8. For example, it is set to 20 ° C. or lower, preferably 10 ° C. or lower, and more preferably 0 ° C. or lower.

Specifically, the three-way valve 31 is closed from the first position between the decompression third branch line 17B and the second decompression line 16B, and between the decompression fourth branch line 18B and the second decompression line 16B. Is set to a position (second position) where is opened.
At the same time, the first on-off valve 29 and the second on-off valve 30 are controlled by the CPU 50, and in the air line 11, the dehumidifying side of the second evaporator 9 is connected from the dehumidifying side first passage 27 of the first evaporator 8. The connection is switched to the second passage 28. Specifically, the second on-off valve 30 is opened and the first on-off valve 29 is closed.

Therefore, the supply of the refrigerant is stopped to the first evaporator 8 after switching. Therefore, it is possible to prevent further generation of frost, and at the same time, a part of the air flows into the cooling source side first passage 19 of the first evaporator 8 through the first bypass 13, and further, by heat transfer from the surroundings, Since the temperature of the 1st evaporator 8 rises, the frost adhering to the 1st evaporator 8 can be removed reliably.
On the other hand, the second evaporator 9 after switching is supplied with air containing a large amount of refrigerant and moisture. Therefore, the dehumidification of air can be continued by the second evaporator 9 continuously from the first evaporator 8.

As a result, it is possible to continue dehumidification of air while preventing further generation of frost and at the same time reliably removing frost attached to the first evaporator 8. Therefore, it is possible to increase the drying efficiency of the resin by drying air with a low dew point while saving energy.
Further, the CPU 50 controls switching of the three-way valve 31 and switching of the first on-off valve 29 and the second on-off valve 30 based on the temperature measurement of the first temperature sensor 24. Therefore, after detecting the generation of frost in the first evaporator 8 based on the temperature measurement of the first temperature sensor 24, the three-way valve 31, the first on-off valve 29, and the second on-off valve 30 can be switched. Since it can do, the frost in the 1st evaporator 8 can be removed efficiently.

Furthermore, after the above switching, air can be supplied to the first evaporator 8 by the first bypass 13, so that the temperature of the first evaporator 8 is raised and frost adhering to the first evaporator 8 is effectively and effectively removed. It can be removed reliably.
Furthermore, after the above switching, when the air supplied to the first evaporator 8 is 5 to 95% with respect to the air circulating in the air line 1, frost adhering to the first evaporator 8. Can be more effectively and reliably removed.

  Next, in the second evaporator 9, when the temperature measured by the second temperature sensor 25 measures the temperature indicating that frost is attached to the outer surface of the cooling source side second passage 20, the CPU 50 performs three-way measurement. The valve 31 is controlled to switch the connection of the cooling side second passage 20 of the second evaporator 9 to the cooling side first passage 19 of the first evaporator 8 in the refrigerant line 10. The temperature indicating that frost is attached to the outer surface of the cooling source side second passage 20 is the same as described above.

Specifically, the three-way valve 31 is set from the second position to the first position. At the same time, the first on-off valve 29 and the second on-off valve 30 are controlled by the CPU 50, and in the air line 11, the dehumidification side first of the first evaporator 8 is passed from the dehumidification side second passage 28 of the second evaporator 9. The connection is switched to the passage 27. Specifically, the first on-off valve 29 is opened and the second on-off valve 30 is closed.
Thereafter, the first evaporator 8 and the second evaporator 9 are selectively switched by repeatedly switching the three-way valve 31 and switching the first on-off valve 29 and the second on-off valve 30. Thus, the air is continuously dehumidified and dried.

In the drying hopper 3, when it is measured that the third temperature sensor 45 does not reach the predetermined temperature, the CPU 50 controls the auxiliary heater 32 provided as necessary, and the air flowing through the second heating line 23B is supplied. It can be supplementarily heated and an efficient drying of the resin requiring a high drying temperature can be achieved.
On the other hand, when the drying hopper 3 determines that the third temperature sensor 45 has exceeded the predetermined temperature, the CPU 50 causes the third on-off valve 36 of the third bypass 12 to be opened to the atmosphere and the air generated by the condenser 6 is opened. Excessive heating can be prevented. Alternatively, the CPU 50 can reduce the amount of refrigerant compressed by the compressor 5, reduce the amount of heat exchange in the condenser 6, and prevent excessive heating of the air.

In the above description, the two evaporators of the first evaporator 8 and the second evaporator 9 are provided as a plurality of evaporators, but the number is appropriately selected according to the application and purpose. Two or more can be provided.
Although not shown, a third evaporator can be provided instead of the oil separator 33. The third evaporator (not shown) is configured in the same manner as the first evaporator 8 and the second evaporator 9. The third evaporator removes volatile components (oil components) contained in a small amount in the air supplied from the drying hopper 3.

In the above description, the CPU 50 is controlled based on the temperature measurement by the first temperature sensor 24 in the first evaporator 8. For example, although not shown, the CPU 50 is provided in the CPU 50 and the first three-way valve 31 and the first A timer as time measuring means (not shown) for measuring a predetermined time for switching between the on-off valve 29 and the second on-off valve 30 can be used.
The predetermined time for switching the first on-off valve 29 and the second on-off valve 30 is appropriately set according to, for example, the capacity of the first evaporator 8, and is set to, for example, 10 to 120 minutes, preferably 30 to 60 minutes. Is done.

If a timer is used, the three-way valve 31 and the first on-off valve 29 and the second on-off valve 30 are switched by time control after detecting the occurrence of frost in the first evaporator 8 based on the time measurement. Therefore, frost in the first evaporator 8 can be easily and efficiently removed.
In the above description, the switching of the three-way valve 31 and the switching of the first on-off valve 29 and the second on-off valve 30 were performed simultaneously. For example, after a predetermined time has elapsed since the switching of the three-way valve 31, The first on-off valve 29 and the second on-off valve 30 can be switched. The predetermined time from the switching of the three-way valve 31 to the switching of the first on-off valve 29 and the second on-off valve 30 is, for example, ˜min, preferably ˜min.

  In the predetermined time from the switching of the three-way valve 31, that is, immediately after the switching of the three-way valve 31 from the first position to the second position, until the second on-off valve 30 is opened and the first on-off valve 29 is closed. Low-temperature refrigerant still remains in the cooling source side first passage 19 of the one evaporator 8. And the air which passes the dehumidification side 1st channel | path 27 of the 1st evaporator 8 can be dehumidified using the low temperature refrigerant | coolant as a cooling source. Therefore, energy saving can be achieved.

FIG. 2 is an apparatus configuration diagram showing another embodiment of the heat pump type drying apparatus of the present invention. In addition, about the part corresponding to each above-mentioned part, the same referential mark is attached | subjected in FIG. 2, and the detailed description is abbreviate | omitted.
In the above description, a resin heater or the like is not provided on the upstream side of the drying hopper 3 in the resin supply direction. For example, as shown in FIG. 2, the supply direction of the hot air line 37 inserted into the drying hopper 3 A resin heater 39 can be provided on the upstream side.

Thus, in the hot air line 37, air is heated by the resin heater 39, and hot air is blown onto the resin by the drying hopper 3 (or a second drying hopper 38 described later), thereby efficiently heating the resin. Can be dried.
Furthermore, in the above description, the single drying hopper 3 has been exemplified as the drying tank. However, for example, as shown in FIG. 2, two drying hoppers, that is, the first drying hopper 3 and the second drying hopper 3 are used. The hopper 38 can be provided in series.

The second drying hopper 38 is provided on the upstream side of the first drying hopper 3 in the resin supply direction, and is connected to the first drying hopper 3 via the supply line 40.
Thereby, in the second drying hopper 38, the resin is heated by the hot air supplied from the hot air line 37, and then the resin is supplied to the first hopper 3 through the supply line 40 and supplied from the air line 11. Dry with dehumidified air. Therefore, the first drying hopper 3 and the second drying hopper 38 can dehumidify and dry the resin more efficiently.

As shown by phantom lines in FIGS. 1 and 2, the first dehumidification line 22 </ b> A and the second dehumidification line 22 </ b> B serve as an evaporation side bypass for bypassing the first evaporator 8 and the second evaporator 9. The fourth bypass 48 can be provided. The fourth bypass 48 branches from the first dehumidification line 22A between the first filter 51 and the oil separator 33 and is connected to the second dehumidification line 22B between the second filter 52 and the blower 4. .
The fourth bypass 48 is provided with a fourth on-off valve 49, as indicated by the phantom lines in FIGS. The fourth on-off valve 49 is connected to the CPU 50.

  Then, the connection is switched from the dehumidification side first passage 27 of the first evaporator 8 to the dehumidification side second passage 28 of the second evaporator 9, and the dehumidification side first passage of the first evaporator 8 is switched by the first bypass 13. When air is supplied to the first passage 27 and frost adhering to the dehumidifying side first passage 27 is removed, when air is excessively supplied to the dehumidifying side first passage 27, water drops ( Water) may be mixed in the air and circulate through the air line 11 again.

  However, according to this heat pump type drying apparatus 1, the fourth on-off valve 49 is controlled by the CPU 50, the fourth on-off valve 49 is opened, and the air flows into the fourth bypass 48 so that the air is on the dehumidifying side. By bypassing the one passage 27 (and the dehumidifying side second passage 28), it is possible to prevent the circulation of air mixed with water droplets (water) generated from frost and to circulate the air with a low dew point.

FIG. 1 is an apparatus configuration diagram showing an embodiment (an aspect in which one drying hopper is provided) of a heat pump type drying apparatus of the present invention. FIG. 2 is an apparatus configuration diagram showing another embodiment (an aspect in which a first drying hopper and a second drying hopper are provided) of the heat pump type drying apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat pump type drying apparatus 2 Heat pump unit 3 Drying hopper (1st drying hopper)
4 Blower 5 Compressor 6 Condenser 7 Expansion Valve 8 First Evaporator 9 Second Evaporator 10 Refrigerant Line (Heat Medium Line)
12 3rd bypass 13 1st bypass 14 2nd bypass 24 1st temperature sensor 25 2nd temperature sensor 29 1st on-off valve 30 2nd on-off valve 31 3 way valve 32 auxiliary heater 33 oil separator 38 2nd drying hopper 48 4th Bypass 50 CPU

Claims (9)

A heat pump unit comprising a compressor, a condenser, an expansion valve and a plurality of evaporators;
A drying tank in which the resin is dried;
A blowing means for blowing air to the drying tank;
A heating medium line that connects the compressor, the condenser, the expansion valve, and the optional evaporator, and in which a heating medium is circulated;
An air line for connecting the blowing means, the condenser, the drying tank and the optional evaporator, and circulating air;
A heat medium switching means for switching the evaporator connected to the heat medium line;
Air switching means for switching the evaporator connected to the air line;
Control means for controlling the heat medium switching means and the air switching means,
The control means controls the heat medium switching means to switch any evaporator connected to the heat medium line to another evaporator not connected to the heat medium line; and Controlling the air switching means to switch any evaporator connected to the air line to another evaporator not connected to the air line ;
The control means is provided with a time measuring means for measuring a time for switching the heat medium switching means and the air switching means,
The heat pump type drying apparatus, wherein the control means controls the heat medium switching means and the air switching means based on the time measurement of the time measuring means . The evaporator is provided with temperature detection means for detecting the temperature of the evaporator,
The heat pump-type drying apparatus according to claim 1, wherein the control means controls the heat medium switching means and the air switching means based on temperature detection of the temperature detection means. The heat pump-type drying apparatus according to claim 1 or 2 , wherein the air line is provided with a supply means for supplying air to the evaporator not connected to the air line. . The heat pump-type drying according to claim 3 , wherein the air supplied to the evaporator not connected to the air line is 5 to 95% with respect to the air circulating in the air line. apparatus. The heat pump drying apparatus according to any one of claims 1 to 4, wherein the air line is provided with an evaporation side bypass for allowing air to bypass the plurality of evaporators. Wherein the air line, upstream and downstream of the condenser of the drying tank, wherein the heating means for heating the air are connected, according to any of claims 1 to 5 Heat pump type drying equipment. The removal means for removing the volatile component in air is connected to the said air line in the downstream of the said drying tank, and the upstream of the said evaporator, The Claim 1-6 characterized by the above-mentioned. The heat pump type drying apparatus according to any one of the above. The heat pump dryer according to any one of claims 1 to 7 , wherein the air line is provided with a condensing side bypass for air to bypass the condenser. The heat pump drying apparatus according to any one of claims 1 to 8 , wherein the compressor compresses the heat medium in multiple stages.

Images