JP5531246B2 - Compressed air dehumidifier - Google Patents

Description

  The present invention relates to a compressed air dehumidifier.

There is a compressed air dehumidifying device that dehumidifies by cooling compressed air with a refrigeration circuit. In this compressed air dehumidifier, the compressed air is cooled, so there is a risk of dew condensation on the secondary (exit side) air piping. Therefore, the secondary side compressed air is reheated (reheated) to prevent condensation. Moreover, it is advantageous in that the amount of air can be increased by heating.
Various methods for heating the compressed air on the secondary side have been studied. One example is the use of an electric heater, but this is not preferable because the power consumption increases.

Therefore, in the compressed air dehumidifying device 10 shown in Patent Document 1, as shown in FIG. 2, the refrigerant flow path 12 from the compressor 11 is branched, and the high-temperature refrigerant flowing in the branched refrigerant flow path 13 and the secondary side of the refrigerant flow path Refrigerant reheat system that exchanges heat with compressed air is adopted.
In FIG. 2, the compressor 11, the refrigerant flow path 12, the flow rate adjusting valve 14, the condenser 15, the expansion valve 16, the evaporator 17 (cooler), and the circulation circuit of the compressor 11 constitute a cooling circuit. On the other hand, the compressed air is supplied from the compressed air inlet 18 to the heat exchanger constituted by the evaporator 17 through the pipe 19, cooled by this heat exchanger, dehumidified, and heated at a high temperature flowing through the branch refrigerant flow path 13. The refrigerant is reheated by the reheater 21 and supplied from the compressed air outlet 22 to a required location. A temperature sensor 23 is disposed at the compressed air outlet 22, and the opening degree of the flow rate adjusting valves 14, 20 is controlled by the control unit 24 so that the temperature detected by the temperature sensor 23 becomes a required set temperature. .

JP 2010-104964

With the thing of patent document 1, power consumption can be made small and energy saving can be achieved. However, in the refrigerant reheat method shown in Patent Document 1, when the compressed air circuit fluctuates from a low load (air stop or low air flow rate, at low air temperature) to a high load (rated air flow rate, at low air temperature), The temperature capability is low, the accuracy of temperature control is poor, low temperature air flows out and cannot reach the required set temperature, and there is a risk of causing condensation on the pipe surface.
The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to prevent the outflow of low-temperature air even when there is a load fluctuation as described above, and to have a high temperature control responsiveness and high accuracy. Another object of the present invention is to provide a compressed air dehumidifier capable of controlling the temperature.

  In the compressed air dehumidifying apparatus according to the present invention, the first branch of the first branch channel and the second branch channel where the refrigerant sent from the compressor to the refrigerant channel branches from the refrigerant channel. Compressed air that is distributed to the flow path by the distributor and circulated in the order of the first condenser, the first expansion valve, the first evaporator (cooler), and the compressor, and the compressed air inlet Compressed air dehumidifying device comprising: a compressed air circulation section that is cooled and dehumidified by the first evaporator (cooler) of the cooling circuit and then reheated by the reheat section and flows out from the compressed air outlet In the above, the refrigerant sent from the compressor to the refrigerant flow path is distributed from the distributor to the second branch flow path, and the second condenser (heater) and the second expansion valve constituting the reheat unit. The exhaust heat of the first condenser of the cooling circuit Heat the second evaporator, and the is characterized in that it comprises a reheat circuit is circulated to the compressor is merged into the refrigerant flow path on the downstream side of the first evaporator of the cooling circuit.

The first temperature sensor for detecting the temperature of the compressed air on the compressed air outlet side of the compressed air circulation section, and the temperature of the compressed air on the outlet side detected by the first temperature sensor become the required set temperature. As described above, the controller includes a control unit that controls the amount of refrigerant flowing through the first branch flow path and the second branch flow path by the distributor.
In addition, an air flow detection sensor that detects a flow of compressed air in the compressed air circulation section, and a second temperature sensor that detects a refrigerant temperature on the outlet side of the second condenser (heater) of the reheat circuit. The control unit is detected when the air flow flowing through the compressed air circulation unit is not detected by the air flow detection sensor, or when the air flow is smaller than a required set value, and detected by the second temperature sensor. When the temperature of the refrigerant becomes higher than a required set value, the distributor is controlled so that the refrigerant does not flow into the second branch flow path.

  According to the present invention, even if there is a load fluctuation (air flow stoppage or air flow fluctuation), the compressed air dehumidifier is capable of controlling the temperature with high accuracy without causing low temperature air to flow out, having good temperature control responsiveness. Can provide.

It is a circuit diagram which shows the cooling circuit and compressed air circulation part of the compressed air dehumidification apparatus in this Embodiment. It is a circuit diagram which shows the cooling circuit and compressed air circulation part of the conventional compressed air dehumidification apparatus.

Hereinafter, a preferred embodiment of a compressed air dehumidifying device 30 according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a circuit diagram showing a cooling circuit X and a compressed air circulation part Y of the compressed air dehumidifying device 30 in the present embodiment.
In the cooling circuit X, the refrigerant sent from the compressor 31 that compresses the refrigerant to the refrigerant flow channel 32 is the first of the first branch flow channel 33 and the second branch flow channel 34 that branch from the refrigerant flow channel 32. Distributed to one branch channel 33 by a distributor (flow rate adjusting valves 35, 36), a first condenser 37, a first expansion valve 38, a first evaporator (cooler: heat exchanger) 39, and a compressor It is circulated in the order of 31. The opening degree of the flow rate adjusting valves 35 and 36 can be controlled by the control unit 40. In this case, the sum of the refrigerant flow rates of the flow rate adjustment valve 35 and the flow rate adjustment valve 36 is controlled to be always 100%.
Although the distributor is composed of the two flow control valves 35 and 36, it may be composed of one three-way flow control valve. The expansion valve 38 is an example of a pressure reducing mechanism that adiabatically expands the refrigerant. However, the expansion valve 38 is used in a concept including a capillary tube in addition to an electronic expansion valve (an expansion valve 49 in the reheat circuit Z described later is also the same). .

  In the compressed air circulation part Y, the compressed air flowing in from the compressed air inlet 42 is cooled by passing through the first evaporator (cooler) 39 of the cooling circuit X through the pipe 43, and the generated water droplets are not shown. It is dehumidified by being discharged through the drain valve, and then reheated by a second condenser (heater) 48 which is a reheat part in a reheat circuit Z described later, and then flows out from the compressed air outlet 44.

  In the reheat circuit Z, the refrigerant sent from the compressor 31 to the refrigerant flow path 32 is distributed from the distributor (flow rate adjusting valves 35 and 36) to the second branch flow path 34, and the second condensation constituting the reheat section. Downstream of the first evaporator (cooler) 39 in the cooling circuit X, and the second evaporator 50 that absorbs the exhaust heat of the first condenser 37 in the cooling circuit X, the second expansion valve 49, the second expansion valve 49 The refrigerant flows into the refrigerant flow path 32 on the side and is circulated to the compressor 31.

The second condenser 48 in the reheat circuit Z is reheated to the required temperature by reheating the low-temperature compressed air that has been cooled and dehumidified by the first evaporator 39 with the refrigerant that has been compressed by the compressor 31 to a high temperature. Let
Further, the first condenser 37 of the cooling circuit X and the second evaporator 50 of the reheat circuit Z are arranged in series (in series as the wind flow of the blower fan 51), and the exhaust heat of the first condenser 37 is blown. Heat is efficiently exchanged by blowing to the second evaporator 50 by the fan 51. That is, the reheat circuit Z is configured as a heat pump circuit that effectively uses the exhaust heat on the cooling circuit X side, and efficiently reheats the compressed air in the second condenser (heater) 48.

The compressed air circulation section Y is provided with an air flow detection sensor 53 that detects the flow of compressed air, and detects the presence or absence of the air flow. An air flow presence / absence detection signal is input to the control unit 40. The airflow detection sensor 53 can employ various configurations.
A first temperature sensor 54 that detects the temperature of the compressed air is disposed at the compressed air outlet of the compressed air circulation section Y. A detection signal of the compressed air temperature detected by the first temperature sensor 54 is input to the control unit 40.
Further, a second temperature sensor 55 that detects the refrigerant temperature at the outlet side of the second condenser (heater) 48 as a reheat portion of the reheat circuit Z is disposed. This detected refrigerant temperature detection signal is also input to the controller 40.
A hot gas bypass circuit 57 bypasses the outlet side and the suction side of the compressor 31 and is normally closed by an on-off valve 58. As will be described later, the open / close valve 58 is opened during no-load operation. In the no-load operation with no air flow, the inside of the heat exchanger (in the first evaporator 39) is supercooled, and there is a risk of condensation water freezing. Therefore, freezing is prevented by bypassing the high-temperature and high-pressure refrigerant discharged from the compressor 31 so that the temperature in the heat exchanger (inside the first evaporator 39) does not reach the freezing temperature.

The compressed air dehumidifier 30 in the present embodiment is configured as described above.
During normal operation in which compressed air is circulated through the compressed air circulation section Y, the refrigerant from the compressor 31 is distributed to the cooling circuit X and the reheat circuit Z through the distributors (flow rate adjusting valves 35 and 36). It is circulated and dehumidified and reheated.
That is, the compressed air containing moisture flowing into the pipe 43 from the compressed air inlet 42 is cooled by the first evaporator (cooler) 39, and the generated water droplets are discharged through a drain valve (not shown). Dehumidified. The dehumidified compressed air in the low temperature state is reheated by the second condenser (heater) 48 serving as a reheat portion by the refrigerant which has been compressed by the compressor 31 and becomes a high temperature. The temperature of the reheated compressed air is detected by the first temperature detection sensor 54, and this detection signal is input to the control unit 40 so that the detection temperature becomes a preset temperature set in advance. In addition, the temperature is adjusted by adjusting the amount of refrigerant flowing through the cooling circuit X and the reheat circuit Z by adjusting the opening degree of the flow rate adjusting valves 35 and 36.

  As described above, in the present embodiment, a heat pump balance control system that adjusts the flow rate of the refrigerant by the distributors (flow rate adjusting valves 35 and 36) and balances the cooling by the cooling circuit X and the reheating by the reheat circuit Z is used. Adopted. And since the exhaust heat in the 1st condenser 37 of the cooling circuit X absorbs heat effectively by the 2nd evaporator 50 of the reheat circuit Z of a heat pump, it becomes excellent in thermal efficiency. Further, since the exhaust heat is recovered, the temperature rise around the apparatus can be prevented, and the environmental load can be reduced.

  More specifically, in the case of the conventional simple reheat method as shown in FIG. 2, the entire amount of the refrigerant is used for cooling by the evaporator (cooler) of the air dryer. In this form (heat pump balance control system), the cooling circuit X and the reheat circuit Z are provided independently, so that only the refrigerant of the cooling circuit X is supplied to the evaporator (cooler) 39 of the compressed air dehumidifier. The Further, the condenser 48 as a reheat part of the reheat circuit Z is an independent circuit, and the exhaust heat of the condenser 37 is also used, so that the heating capacity is improved. When compared with the outlet air temperature, it becomes possible to control the temperature up to +5 deg higher than the conventional reheat method.

In the case of the conventional reheat method, the temperature control function is given priority over the compressed air dehumidification function, so the cooling capacity is 100%, the heating capacity is 130%, and the cooling and heating are one circuit, so the actual heating capacity is only 30%. Absent. In this regard, in the case of the heat pump balance control system, the cooling and heating circuits are independent of each other, so that the cooling capacity is 100% to 0%, the heating capacity is 130% to 0%, and 100% when cooling is not required. Can be heated. Therefore, compared with the conventional reheat system, it has a heating capacity of 130/30 = 4.3 times and can be heated quickly.
Further, in the case of the heat pump balance control method, the cooling circuit X and the reheat circuit Z are independent and the refrigerant distribution ratio can be controlled, so that fine distribution control can be performed with respect to fluctuations in the inlet air temperature (load). The temperature can be controlled with high accuracy (± 0.1 ° C.).

  The compressed air dehumidifier may be operated without load. The no-load operation refers to an operation in a state where there is no flow in the compressed air circuit and no load is applied to the compressed air dehumidifier. That is, in the case of compressed air, if the user does not use air, the air pressure is applied but the flow is stopped. In this case, heat exchange in the second condenser 48 that is a reheat portion is eliminated, so that the temperature of the refrigerant in the second condenser 48 may be excessively increased.

  Therefore, in this embodiment, the air flow detection sensor 53 is provided, and when the air flow flowing through the compressed air circulation unit Y is not detected by the air flow detection sensor 53, or when the air flow is smaller than a required set value, the control unit 40 closes the flow control valve 36 in the distributor. That is, the reheat circuit Z is closed. Thereby, it can prevent that the temperature of the refrigerant | coolant in the 2nd condenser 48 of the reheat circuit Z rises too much. Further, since no-load operation is performed, as described above, the on-off valve 58 of the hot gas bypass circuit 57 is opened to prevent the condensed water from freezing in the heat exchange (in the first evaporator 39).

  Depending on the air flow detection sensor 53, there is a possibility that a minute air flow cannot be detected due to a physical or mechanical detection mechanism. That is, although it is being used little by little by the user, it may not be detected because of the minute air flow. Therefore, in addition to the detection of the air flow by the air flow detection sensor 53, the temperature of the refrigerant on the outlet side of the second condenser 48 is detected by the second temperature sensor 55, and the temperature of the refrigerant is lower than the required set value. The reheat circuit Z is closed when it becomes higher. If the temperature of the refrigerant is within the required set value, even if the air flow is not detected by the air flow detection sensor 53, the user determines that the air flow is being used but does not close the reheat circuit Z. It is.

In the present embodiment, since the reheat circuit Z that constitutes the heat pump that effectively uses the exhaust heat in the cooling circuit X as described above is provided, the above-described effect of efficiently reheating the dehumidified compressed air can be achieved. .
Furthermore, by increasing the supply amount of the dehumidified compressed air, the driving power amount of the air compressor per accumulated compressed air can be relatively lowered, and an energy saving effect can be obtained.
Furthermore, since the temperature in the piping in the compressed air dehumidifier can be increased, the occurrence of condensation can be suppressed in winter and the like. For this reason, measures, such as winding a heat insulating material around piping, can be made unnecessary.

30 Compressed air dehumidifier 31 Compressor 32 Refrigerant flow path 33 First branch flow path 34 Second branch flow path 35 Flow rate adjustment valve 36 Flow rate adjustment valve 37 First condenser 38 First expansion valve 39 First evaporator ( Cooler)
40 Control unit 42 Compressed air inlet 43 Piping 44 Compressed air outlet 48 Second condenser (heater)
49 Second expansion valve 50 Second evaporator 51 Blower fan 53 Air flow detection sensor 54 First temperature sensor 55 Second temperature sensor 57 Hot gas bypass circuit 58 On-off valve X Cooling circuit Y Compressed air circulation part Z Reheat circuit

Claims (3)

The refrigerant sent from the compressor to the refrigerant flow path is distributed by the distributor to the first branch flow path among the first branch flow path and the second branch flow path branched from the refrigerant flow path. 1 condenser, 1st expansion valve, 1st evaporator (cooler), and the cooling circuit circulated in the order of the said compressor,
Compressed air flowing from the compressed air inlet is cooled by the first evaporator (cooler) of the cooling circuit, dehumidified, reheated by the reheat unit, and discharged from the compressed air outlet. A compressed air dehumidifying device comprising:
Refrigerant sent from the compressor to the refrigerant flow path is distributed from the distributor to the second branch flow path, and includes a second condenser (heater), a second expansion valve, and the reheat unit. A second evaporator that absorbs exhaust heat of the first condenser of the cooling circuit, and a reheat circuit that is joined to the refrigerant flow path downstream of the first evaporator of the cooling circuit and circulated to the compressor A compressed air dehumidifying device comprising: A first temperature sensor for detecting the temperature of the compressed air on the compressed air outlet side of the compressed air circulation section;
The amount of refrigerant flowing through the first branch flow path and the second branch flow path by the distributor is adjusted so that the temperature of the compressed air on the outlet side detected by the first temperature sensor becomes a required set temperature. The compressed air dehumidifier according to claim 1, further comprising a control unit that controls the compressed air dehumidifier. An air flow detection sensor for detecting a flow of compressed air in the compressed air circulation section;
A second temperature sensor for detecting a refrigerant temperature on the outlet side of the second condenser (heater) of the reheat circuit,
The control unit is configured such that when the air flow flowing through the compressed air circulation unit is not detected by the air flow detection sensor, or when the air flow is smaller than a required set value, and the refrigerant detected by the second temperature sensor The compressed air dehumidifying device according to claim 2, wherein when the temperature becomes higher than a required set value, the distributor is controlled so that the refrigerant does not flow into the second branch flow path.

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