JP7022772B2 - Refrigerating equipment and how to use the refrigerating equipment - Google Patents

Description

The present invention relates to a refrigerating apparatus and a method of using the refrigerating apparatus.

From the viewpoint of preventing ozone layer depletion and warming, NH ₃ is used as the primary refrigerant, which has high cooling performance but is toxic, as a refrigerant for refrigerating equipment used for indoor air conditioning and refrigeration of foods, and is non-toxic and odorless CO ₂ . A refrigerating device using carbon dioxide as a secondary refrigerant is widely used.

In connection with this, for example, in Patent Document 1 below, the main refrigerant circuit in which the NH ₃ refrigerant circulates, an oil-cooled two-stage screw compressor composed of a low-stage compressor and a high-stage compressor, and condensation. A refrigerating apparatus provided with a vessel, an evaporator, and an expansion valve is disclosed.

Japanese Unexamined Patent Publication No. 2015-209977

In the oil-cooled two-stage screw compressor, the low-stage screw rotor and the high-stage screw rotor are rotated by a motor. Then, for example, in the initial stage when the object is started to be cooled under the load to be cooled, the suction pressure of the NH ₃ refrigerant sucked into the compressor becomes high, and the motor may be overloaded.

The present invention has been made to solve the above problems, and is a freezing device and a freezing device capable of freezing operation while suppressing an overload of a motor for driving a compressor. The purpose is to provide a usage method.

In the refrigerating apparatus according to the present invention that achieves the above object, the first refrigerant circulates, the primary refrigerant circuit in which the compressor, the condenser, the expansion valve, and the evaporator are arranged, and the second refrigerant circulates, and the above evaporation A secondary refrigerant circuit connected to the condenser and the cooling load, and a direct contact economizer provided in the primary refrigerant circuit between the condenser and the evaporator to supply the cooled primary refrigerant gas to the compressor. , A bypass path that branches from the primary refrigerant circuit on the upstream side of the expansion valve and joins the primary refrigerant circuit on the downstream side of the direct contact type economizer, and a direct contact type economizer provided in the primary refrigerant circuit. A first valve for adjusting the amount of the first refrigerant flowing into the bypass path, a second valve provided in the bypass path for adjusting the amount of the first refrigerant flowing into the bypass path, and the primary refrigerant circuit are circulated. Based on the detection unit that detects the pressure of the first refrigerant or the pressure or temperature of the second refrigerant circulating in the secondary refrigerant circuit, and the detection value of the detection unit, the first valve and the second valve. It has a control unit that controls the opening and closing of the valve. Further, the compressor is an oil-cooled multi-stage screw compressor including a high-stage compressor, a low-stage compressor, and a motor for driving the high-stage compressor and the low-stage compressor, and is a direct contact type. The economizer is a direct contact type double economyr, and the direct contact type double economyr has a high stage region connected to the high stage compressor and a low stage region connected to the low stage compressor. The primary refrigerant circuit is provided as a branch from the low-stage circuit connecting the low-stage region and the low-stage compressor, and has a connection circuit connected to the housing of the motor, and the control unit has a control unit. When the detection value of the detection unit exceeds the threshold value, the opening degree of the first valve is controlled to the first opening degree, and the second valve is opened.

Further, in the method of using the refrigerating apparatus according to the present invention that achieves the above object, a primary refrigerant circuit in which a first refrigerant circulates and a compressor, a condenser, an expansion valve, and an evaporator are arranged, and a second refrigerant are used. A secondary refrigerant circuit that circulates and is connected to the evaporator and the cooling load, and a primary refrigerant circuit provided in the primary refrigerant circuit between the condenser and the evaporator, supplies the cooled primary refrigerant gas to the compressor. A direct contact economizer, a bypass path that branches from the primary compressor circuit on the upstream side of the expansion valve and joins the primary compressor circuit on the downstream side of the direct contact economizer, and a bypass path that joins the primary compressor circuit are provided in the primary compressor circuit. A first valve that adjusts the amount of the first compressor flowing into the direct contact economizer, a second valve provided in the bypass path and adjusting the amount of the first refrigerant flowing into the bypass path, and the above. The compressor has a detector for detecting the pressure of the first refrigerant circulating in the primary compressor circuit or the pressure or temperature of the second compressor circulating in the secondary compressor circuit, and the compressor is a high-stage compressor. , A low-stage compressor, and an oil-cooled multi-stage screw compressor including the high-stage compressor and a motor for driving the low-stage compressor, wherein the direct-contact economizer is a direct-contact double economizer. The direct contact type double economizer has a high-stage region connected to the high-stage compressor and a low-stage region connected to the low-stage compressor, and the primary refrigerant circuit has the low-stage region. It is a method of using a refrigerating apparatus having a connection circuit branched from a low-stage circuit connecting the region and the low-stage compressor and connected to the housing of the motor . When the detection value of the detection unit exceeds the threshold value, the opening degree of the first valve is controlled to the first opening degree, and the second valve is opened .

According to the refrigerating device and the method of using the refrigerating device described above, in a situation where the motor is overloaded, the motor is operated by opening and closing the first valve and the second valve so that the _NH3 refrigerant flows through the bypass path. Can be suitably suppressed from becoming an overload. Therefore, it is possible to provide a refrigerating apparatus and a method of using the refrigerating apparatus capable of refrigerating operation while suppressing an overload of the motor for driving the compressor.

It is a system diagram of the refrigerating apparatus which concerns on embodiment of this invention. It is a flowchart which shows the use method of the refrigerating apparatus which concerns on this embodiment. It is a system diagram when _NH3 refrigerant circulates in a primary refrigerant circuit in the refrigerating apparatus which concerns on this embodiment. It is a system diagram when the _NH3 refrigerant mainly circulates in the bypass path in the refrigerating apparatus which concerns on this embodiment.

An embodiment of the present invention will be described with reference to FIG. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. The dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

FIG. 1 is a system diagram of the refrigerating apparatus 1 according to the embodiment of the present invention.

As shown in FIG. 1, the refrigerating apparatus 1 includes a primary refrigerant circuit 10 in which an NH ₃ refrigerant (corresponding to a first refrigerant) circulates, and a secondary refrigerant circuit 20 in which a CO ₂ refrigerant (corresponding to a second refrigerant) circulates. , A compressor 30 provided on the primary refrigerant circuit 10, a condenser 40 provided on the primary refrigerant circuit 10, an expansion valve 45 provided on the primary refrigerant circuit 10, and an evaporator provided on the primary refrigerant circuit 10. 50, a direct contact type double economyr (hereinafter, also referred to as a double economyr) 60 provided on the primary refrigerant circuit 10, and a branch from the primary refrigerant circuit 10 on the upstream side of the double economyr 60 and a primary on the downstream side of the double economyr 60. The bypass path 70 that joins the refrigerant circuit 10, the detection unit 80 that detects the pressure of the NH ₃ refrigerant that circulates in the primary refrigerant circuit 10, or the CO ₂ refrigerant that circulates in the secondary refrigerant circuit 20, and the detection values of the detection unit 80. It has a control unit (not shown) for adjusting the flow rate of the primary refrigerant circuit 10 and the bypass path 70 based on the above.

First, the flow of the NH ₃ refrigerant during normal operation will be described. In the evaporator 50, the NH ₃ refrigerant gas evaporated by the heat of the gaseous CO ₂ refrigerant is compressed by the compressor ₃₀ , and the high temperature and high pressure NH ₃ refrigerant gas is cooled in the condenser 40 to be condensed and liquefied. The refrigerant liquid is depressurized by the variable expansion valve 12B, and a part of the refrigerant liquid evaporates in the high stage region 61 of the double economizer 60. The latent heat of vaporization is taken away by a part of the evaporated NH ₃ refrigerant, and the temperature of both the NH ₃ refrigerant liquid and the NH ₃ refrigerant gas drops. Then, only the NH ₃ refrigerant gas flows through the high-stage circuit 13 to the high-stage compressor 31 of the compressor 30.

The NH ₃ refrigerant liquid discharged from the high stage region 61 of the double economizer 60 is depressurized by the expansion valve 14A, a part of it evaporates in the low stage region 62 of the double economizer 60, and the temperatures of both the NH ₃ refrigerant liquid and the NH ₃ refrigerant gas are high. Descent. Then, only the NH ₃ refrigerant gas flows through the low-stage circuit 15 to the low-stage compressor 32 of the compressor 30. At this time, a part of the NH ₃ refrigerant gas flows through the connection circuit 16 branched from the low-stage circuit 15 and flows into the housing of the motor 33 of the compressor 30.

The NH ₃ refrigerant liquid discharged from the lower region 62 of the double economizer 60 is depressurized by the expansion valve 45 and sent to the evaporator 50 to be used for cooling the gaseous CO ₂ refrigerant.

Next, the configuration of the refrigerating apparatus 1 according to the present embodiment will be described.

The primary refrigerant circuit 10 includes a first circuit 11 connecting the compressor 30 and the condenser 40, a second circuit 12 connecting the condenser 40 to the high stage region 61 of the double economizer 60, and a high stage region of the double economizer 60. The high-stage circuit 13 connecting the high-stage compressor 31 of the compressor 30 and the compressor 30, the third circuit 14 connecting the high-stage region 61 of the double economizer 60 and the low-stage region 62 of the double economizer 60, and the double economizer 60. A low-stage circuit 15 that connects the low-stage region 62 and the low-stage compressor 32 of the compressor 30, a connection circuit 16 that is branched from the low-stage circuit 15 and is connected to the housing of the motor 33, and a double economizer 60. It has a fourth circuit 17 connecting the lower region 62 and the compressor 50 of the above, and a fifth circuit 18 connecting the economizer 50 and the compressor 30.

As the refrigerating machine oil, an insoluble machine oil having good lubrication performance with respect to the NH ₃ refrigerant and having a higher specific density than the NH ₃ refrigerant (for example, alkylbenzene or the like) is used.

A solenoid valve 12A and a variable expansion valve (corresponding to the first valve) 12B are arranged in the second circuit 12 in order from the upstream. The solenoid valve 12A is always open when the refrigerating device 1 is in operation, and closed when the refrigerating device 1 is stopped. The variable expansion valve 12B is in an open state when the NH ₃ refrigerant circulates in the second circuit 12, and the amount of the NH ₃ refrigerant flowing in the second circuit 12 when the NH ₃ refrigerant circulates in the bypass path 70. Is adjusted to be less or zero.

An expansion valve 14A is arranged in the third circuit 14. The expansion valve 14A expands and depressurizes the NH ₃ refrigerant liquid emitted from the high stage region 61 of the double economizer 60.

The NH ₃ refrigerant gas flowing through the connection circuit 16 flows into the housing of the motor 33, discharges the refrigerating machine oil stored in the housing of the motor 33, and cools the motor 33.

An expansion valve 45 is arranged in the fourth circuit 17.

A first detection unit 81, which will be described later, is arranged in the fifth circuit 18.

The secondary refrigerant circuit 20 has a CO ₂ feed path 21 for sending the CO ₂ refrigerant liquid to a CO ₂ liquid reservoir (not shown) and a CO ₂ return path 22 for returning the CO ₂ refrigerant gas from the CO ₂ liquid reservoir. Have. The CO ₂ liquid reservoir is connected to the cooling load. The CO ₂ return path 22 is provided with a second detection unit 82, which will be described later.

The primary refrigerant circuit 10 and the secondary refrigerant circuit 20 are connected in the evaporator 50 as shown in FIG.

In the present embodiment, the compressor 30 is a single-machine oil-cooled two-stage screw compressor, and includes a high-stage compressor 31, a low-stage compressor 32, and a motor 33. The high-stage compressor 31, the low-stage compressor 32, and the motor 33 have a single rotor shaft and rotation shaft arranged in series and coupled in series with each other. Since the configuration of the single-machine oil-cooled two-stage screw compressor is known, detailed description thereof will be omitted.

The NH ₃ refrigerant gas discharged from the compressor 30 is sent to the condenser 40 via the first circuit 11 and condensed.

In the present embodiment, the condenser 40 is composed of a shell-and-plate heat exchanger. The condenser is not limited to the shell-and-plate heat exchanger.

A cooling circuit 41 is guided to the condenser 40. As the liquid circulating in the cooling circuit 41, it is preferable to use an antifreeze liquid from the viewpoint of preventing a freezing accident of the liquid staying in the cooling circuit 41 while the refrigerating device 1 is stopped. The antifreeze liquid circulating in the cooling circuit 41 is heated by the NH ₃ refrigerant in the condenser 40. The liquid circulating in the cooling circuit 41 is not limited to the antifreeze liquid, and may be cooling water.

The cooling circuit 41 is connected to the cooling tower. The antifreeze liquid circulates in the cooling circuit 41 by the cooling water pump. The antifreeze liquid that has absorbed the waste heat of the NH ₃ refrigerant in the condenser 40 comes into contact with the outside air and the spray water in the cooling tower, and is cooled by the latent heat of evaporation of the spray water.

The evaporator 50 is of a shell-and-plate type full-liquid type, and an NH ₃ refrigerant is introduced on the shell side and a CO ₂ refrigerant is introduced on the plate side. Inside the evaporator 50, a plate polymer composed of a large number of plates is arranged. The evaporator 50 is connected to the CO ₂ feed path 21 and the CO ₂ return path 22 of the secondary refrigerant circuit 20. The evaporator is not limited to the shell and plate type. Furthermore, the evaporator is not limited to the full liquid type.

A fifth circuit 18 of the primary refrigerant circuit 10 is connected to the upper part of the evaporator 50.

The NH ₃ refrigerant liquid flowing into the evaporator 50 via the expansion valve 45 absorbs latent heat of vaporization from the CO ₂ refrigerant gas returned from the CO ₂ return path 22 and vaporizes, and liquefies the CO ₂ refrigerant gas. The vaporized NH ₃ refrigerant is sucked into the compressor 30 via the fifth circuit 18. The liquefied CO ₂ refrigerant liquid is sent to a CO ₂ liquid reservoir (not shown) through the CO ₂ feed path 21.

The direct contact type double economizer 60 has a high step region 61 and a low step region 62. The high-stage region 61 and the low-stage region 62 are partitioned by a partition plate 63.

The inside of the high-stage region 61 and the low-stage region 62 is depressurized. The NH ₃ refrigerant liquid cooled and liquefied by the condenser 40 is depressurized by the variable expansion valve 12B and temporarily stored in the high stage region 61 of the double economizer 60. Since the inside of the high-stage region 61 is depressurized, a part of the stored NH ₃ refrigerant liquid is vaporized. When a part of the NH ₃ refrigerant is vaporized, the heat of vaporization is taken from the NH ₃ refrigerant liquid to cool it, and the vaporized NH ₃ refrigerant gas itself becomes low in temperature, and this NH ₃ refrigerant gas passes through the high-stage circuit 13. , Is supplied to the high-stage compressor 31 of the compressor 30.

On the other hand, the NH ₃ refrigerant liquid in the high stage region 61 is depressurized by the expansion valve 14A and temporarily stored in the low stage region 62 of the double economizer 60. Since the inside of the lower region 62 is depressurized, a part of the stored NH ₃ refrigerant liquid is vaporized. When a part of the NH ₃ refrigerant is vaporized, the heat of vaporization is taken from the NH ₃ refrigerant liquid to cool it _, and the vaporized NH ₃ refrigerant gas itself becomes low in temperature. , It is supplied to the low-stage compressor 32 of the compressor 30, and is also supplied into the housing of the motor 33 of the compressor 30 via the connection circuit 16.

A high-stage level sensor 61A is provided in the high-stage region 61 of the double economizer 60, and a low-stage level sensor 62A is provided in the low-stage region 62.

The high-stage level sensor 61A detects the liquid level of the NH ₃ refrigerant stored in the high-stage region 61. The low-stage level sensor 62A detects the liquid level of the NH ₃ refrigerant stored in the low-stage region 62.

The high-stage level sensor 61A and the low-stage level sensor 62A indicate that the liquid level of the NH ₃ refrigerant liquid is low when the signal of the sensor is on, and the NH ₃ refrigerant is when the signal of the sensor is off. Indicates that the liquid is full or that the sensor is out of order. In the following description, the high-stage level sensor 61A and the low-stage level sensor 62A may be collectively referred to as a level sensor.

The bypass path 70 is provided so as to branch from the primary refrigerant circuit 10 on the upstream side of the double economizer 60 and join the primary refrigerant circuit 10 on the downstream side of the double economizer 60. The bypass path 70 is provided by branching from the second circuit 12 and joins the fourth circuit 17.

A solenoid valve 70A (corresponding to a second valve) and an expansion valve 70B are provided in the bypass path 70 in order from the upstream. The solenoid valve 70A is closed when the NH ₃ refrigerant circulates in the primary refrigerant circuit 10, and is opened when the NH ₃ refrigerant circulates in the bypass path 70. The expansion valve 70B can appropriately reduce the pressure when the NH ₃ refrigerant passes through the bypass path 70.

The detection unit 80 is provided in the fifth circuit 18, the first detection unit 81 for detecting the inflow pressure of the NH ₃ refrigerant flowing into the low-stage compressor 32 of the compressor 30, and the CO ₂ return path 22. The second detection unit 82 that detects the pressure of the CO ₂ refrigerant circulating in the secondary refrigerant circuit 20 and the pressure of the NH ₃ refrigerant flowing into the high-stage compressor 31 of the compressor 30 provided in the high-stage circuit 13 are detected. It has a third detection unit 83 and a third detection unit 83. A known pressure sensor can be used as the first detection unit 81 to the third detection unit 83.

Next, a method of using the refrigerating apparatus 1 according to the above-described embodiment will be described with reference to FIGS. 2 to 4. FIG. 2 is a flowchart showing a method of using the refrigerating apparatus 1 according to the present embodiment. FIG. 3 is a system diagram when the NH ₃ refrigerant circulates in the primary refrigerant circuit 10 in the refrigerating apparatus 1 according to the present embodiment. FIG. 4 is a system diagram of the refrigerating apparatus 1 according to the present embodiment when the NH ₃ refrigerant mainly circulates in the bypass path 70.

First, the operation of the refrigerating device 1 is started. At this time, since the pressure value detected by the first detection unit 81 to the third detection unit 83 is higher than the threshold value, as shown in FIG. 4, the variable expansion valve 12B so that the NH ₃ refrigerant flows through the bypass path 70. The opening degree of the solenoid valve 70A is set to 30%, and the solenoid valve 70A is opened (S101). The opening degree of the variable expansion valve 12B at this time is not limited to 30%.

Next, it is detected whether the signal of the level sensor of the double economizer 60 is off (S102).

When the signal of the level sensor of the double economizer 60 is off (S102: YES), the solenoid valve 70A is opened and the opening degree of the variable expansion valve 12B is set to 30% (S103). The opening degree of the variable expansion valve 12B at this time is not limited to 30%. Here, the fact that the signal of the level sensor of the double economizer 60 is off means that the inside of the double economizer 60 is full or the level sensor is out of order.

Next, in the state of S103, it is determined whether the signal of the level sensor is turned on within 180 seconds (S104). When the signal of the level sensor is turned on within 180 seconds in the state of S103 (S104: YES), the amount of NH ₃ refrigerant liquid inside the double economizer 60 is reduced, and the inside of the double economizer 60 is full in S102. Judging that there was, it shifts to S108. The waiting time in S104 is not limited to 180 seconds.

On the other hand, when the signal of the level sensor remains off for 180 seconds in the state of S103 (S104: NO), the opening degree of the variable expansion valve 12B is set to 55% while the solenoid valve 70A is open (S105). ). The opening degree of the variable expansion valve 12B at this time is not limited to 55%. Here, in S102, it is determined that there is a high possibility that the level sensor has failed.

Next, in the state of S105, it is determined whether the signal of the level sensor is turned on within 360 seconds (S106). When the signal of the level sensor is turned on within 360 seconds in the state of S105 (S106: YES), the amount of NH ₃ refrigerant liquid inside the double economizer 60 is reduced, and the inside of the double economizer 60 is full in S102. Judging that there was, it shifts to S108. The waiting time in S106 is not limited to 360 seconds.

On the other hand, if the signal of the level sensor remains off for 360 seconds in the state of S105 (S106: NO), it is determined that the level sensor has failed, a light alarm is issued (S107), and the process proceeds to S111. ..

In S108, it is determined whether or not the pressure value of at least one of the first detection unit 81 to the third detection unit 83 becomes equal to or higher than the threshold value when the NH ₃ refrigerant circulates in the primary refrigerant circuit 10. When it is determined that the pressure value of at least one of the first detection unit 81 to the third detection unit 83 is equal to or higher than the threshold value when the NH ₃ refrigerant circulates in the primary refrigerant circuit 10 (S108: YES), electromagnetic waves are generated. The valve 70A is opened and the opening degree of the variable expansion valve 12B is set to 30% (S109). The opening degree of the variable expansion valve 12B at this time is not limited to 30%. After S109 is performed, the process proceeds to S111.

On the other hand, when all of the pressure values detected by the first detection unit 81 to the third detection unit 83 are less than the threshold value when the NH ₃ refrigerant circulates in the primary refrigerant circuit 10 (S108: NO), electromagnetic waves are generated. The valve 70A is closed and the variable expansion valve 12B is opened (S110). After S110 is performed, the process proceeds to S111.

In S111, it is determined whether the operation command of the refrigerating apparatus 1 is on. When the operation command of the refrigerating apparatus 1 is on (S111: YES), the process returns to S102.

On the other hand, when the operation of the refrigerating apparatus 1 is turned off (S111: NO), the oil recovery operation is performed (S112). At this time, the solenoid valve 70A is opened and the opening degree of the variable expansion valve 12B is set to 30%. The opening degree of the variable expansion valve 12B at this time is not limited to 30%.

Next, the solenoid valves 70A and 12A are closed, and the variable expansion valve 12B is also closed (S113). Then, the operation of the refrigerating device 1 is completed.

As described above, in the refrigerating apparatus 1 according to the present embodiment, the primary refrigerant circuit 10 in which the NH ₃ refrigerant circulates and the compressor 30, the condenser 40, the expansion valve 45, and the evaporator 50 are arranged, and the CO ₂ Refrigerant circulates and is provided in the primary refrigerant circuit 10 between the condenser 40 and the evaporator 50 and the secondary refrigerant circuit 20 connected to the evaporator 50 and the cooling load to compress the cooled NH ₃ refrigerant gas. A bypass that branches from the primary refrigerant circuit 10 on the upstream side of the direct contact type double economyr 60 and the direct contact type double economyr 60, and joins the primary refrigerant circuit 10 on the downstream side of the direct contact type double economyr 60. A variable expansion valve 12B provided in the path 70 and the primary refrigerant circuit 10 to adjust the amount of the NH ₃ refrigerant flowing into the direct contact type double economizer 60, and an NH ₃ provided in the bypass path 70 and flowing into the bypass path 70. Detection of the electromagnetic valve 70A that adjusts the amount of refrigerant, the detection unit 80 that detects the pressure of NH ₃ that circulates in the primary refrigerant circuit 10, or the pressure of the CO ₂ refrigerant that circulates in the secondary refrigerant circuit 20 and the detection unit 80. It has a control unit that controls opening and closing of the variable expansion valve 12B and the electromagnetic valve 70A based on the value. According to the refrigerating apparatus 1 configured in this way, in a situation where the motor 33 is overloaded, the variable expansion valve 12B and the solenoid valve 70A are opened and closed so that the NH ₃ refrigerant flows through the bypass path 70. , It is possible to suitably suppress the motor 33 from becoming overloaded. Therefore, the freezing operation can be performed while suppressing the overload of the motor 33 for driving the compressor 30.

Further, the compressor 30 is an oil-cooled multi-stage screw compressor including a high-stage compressor 31, a low-stage compressor 32, and a motor 33 for driving the high-stage compressor 31 and the low-stage compressor 32, and is an economizer. Is a double economyr 60, and the double economyr 60 has a high-stage region 61 connected to the high-stage compressor 31 and a low-stage region 62 connected to the low-stage compressor 32. According to the refrigerating apparatus 1 configured as described above, the present invention can be suitably applied to the oil-cooled two-stage screw compressor 60.

Further, the primary refrigerant circuit 10 has a connection circuit 16 that is branched from the low-stage circuit 15 that connects the low-stage region 62 and the low-stage compressor 32 and is connected to the housing of the motor 33, and has a control unit. Controls the opening degree of the variable expansion valve 12B to 30% and opens the solenoid valve 70A when the detection value of the detection unit 80 exceeds the threshold value. According to the refrigerating apparatus 1 configured in this way, even when the NH ₃ refrigerant flows through the bypass path 70, the NH 3 refrigerant circulates in the connection circuit 16 as well, so that the NH ₃ refrigerant continuously circulates in the housing of the motor 33. The stored refrigerating machine oil can be discharged and the motor 33 can be cooled.

Further, the high-stage level sensor 61A that detects the liquid level of the NH ₃ refrigerant liquid stored inside the high-stage region 61 and the liquid level of the NH ₃ refrigerant liquid stored inside the low-stage region 62 are detected. Further, the control unit controls the opening degree of the variable expansion valve 12B to 45 to 65% when the high-stage level sensor 61A or the low-stage level sensor 62A fails. Open the solenoid valve 70A. According to the refrigerating apparatus 1 configured as described above, the refrigerating apparatus 1 can be suitably driven even when the high-stage level sensor 61A or the low-stage level sensor 62A fails.

Further, as described above, in the method of using the refrigerating apparatus 1 according to the present embodiment, the NH ₃ refrigerant circulates, and the compressor 30, the condenser 40, the expansion valve 45, and the evaporator 50 are arranged as the primary refrigerant. NH provided and cooled in the circuit 10, the secondary refrigerant circuit 20 in which the CO ₂ refrigerant circulates and is connected to the evaporator 50 and the cooling load, and the primary refrigerant circuit 10 between the condenser 40 and the evaporator 50. ₃ The direct contact type double economyr 60 that supplies the refrigerant gas to the compressor 30 and the primary refrigerant circuit that branches from the primary refrigerant circuit 10 on the upstream side of the direct contact type double economyr 60 and the primary refrigerant circuit on the downstream side of the direct contact type double economyr 60. A bypass path 70 that joins 10 and a variable expansion valve 12B provided in the primary refrigerant circuit 10 that adjusts the amount of NH ₃ refrigerant flowing into the direct contact type double economizer 60, and a bypass path 70 provided in the bypass path 70. An electromagnetic valve 70A that adjusts the amount of NH ₃ refrigerant flowing into the refrigerant, and a detector 80 that detects the pressure of NH ₃ circulating in the primary refrigerant circuit 10 or the pressure of the CO ₂ refrigerant circulating in the secondary refrigerant circuit 20. It is a method of using the refrigerating apparatus 1 having the above. The opening and closing of the variable expansion valve 12B and the solenoid valve 70A are controlled based on the detection value of the detection unit 80. According to the method of using the refrigerating device 1, according to the refrigerating device 1 configured as described above, in a situation where the motor 33 is overloaded, the NH ₃ refrigerant is variably expanded so as to flow through the bypass path 70. By opening and closing the valve 12B and the solenoid valve 70A, it is possible to suitably suppress the motor 33 from being overloaded. Therefore, the freezing operation can be performed while suppressing the overload of the motor 33 for driving the compressor 30.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.

For example, in the above-described embodiment, the NH ₃ refrigerant is used as the refrigerant that circulates in the primary refrigerant circuit 10, and the CO ₂ refrigerant is used as the refrigerant that circulates in the secondary refrigerant circuit 20, but the present invention is not limited thereto. Instead of the CO ₂ refrigerant, antifreeze (brine) or cooling water may be used. When an antifreeze liquid is used instead of the CO ₂ refrigerant, the second detection unit 82 may detect the temperature instead of the pressure.

Further, in the above-described embodiment, the compressor 30 is an oil-cooled two-stage screw compressor, but it may be a single-stage screw compressor.

Further, in the above-described embodiment, the primary refrigerant circuit 10 has a connection circuit 16, but the primary refrigerant circuit does not have to have a connection circuit. When the connection circuit is not provided, it is not necessary to circulate the NH ₃ refrigerant in the connection circuit, so that the opening degree of the variable expansion valve 12B can be set to 0% in FIG. Further, in FIG. 4, instead of setting the opening degree of the variable expansion valve 12B to 0%, the solenoid valve 12A may be closed.

Further, in the above-described embodiment, the refrigerating device 1 has a high-stage level sensor 61A and a low-stage level sensor 62A, but the refrigerating device has a high-stage level sensor 61A and a low-stage level sensor 62A. It does not have to be.

Further, in the above-described embodiment, S105 and S106 may be omitted.

1 Refrigerator,
10 Primary refrigerant circuit,
12B variable expansion valve (first valve),
13 High-stage circuit,
15 low-stage circuit,
16 connection circuit,
20 Secondary refrigerant circuit,
30 compressor,
31 High-stage compressor,
32 low-stage compressor,
33 motor,
40 condenser,
45 expansion valve,
50 evaporator,
60 Direct contact double economizer,
61 High dan area,
61A high level sensor,
62 Low stage area,
62A low level sensor,
70 Bypass,
70A solenoid valve (second valve),
80 Detection unit.

Claims (4)

A primary refrigerant circuit in which the first refrigerant circulates and a compressor, condenser, expansion valve, and evaporator are arranged.
The secondary refrigerant circuit in which the second refrigerant circulates and is connected to the evaporator and the cooling load,
A direct contact economizer provided in the primary refrigerant circuit between the condenser and the evaporator to supply the cooled first refrigerant gas to the compressor.
A bypass path that branches off from the primary refrigerant circuit on the upstream side of the direct contact economizer and joins the primary refrigerant circuit on the downstream side of the direct contact economizer.
A first valve provided in the primary refrigerant circuit and adjusting the amount of the first refrigerant flowing into the direct contact economizer.
A second valve provided in the bypass path and adjusting the amount of the first refrigerant flowing into the bypass path,
A detector that detects the pressure of the first refrigerant circulating in the primary refrigerant circuit or the pressure or temperature of the second refrigerant circulating in the secondary refrigerant circuit.
It has a control unit for controlling the opening and closing of the first valve and the second valve based on the detection value of the detection unit.
The compressor is an oil-cooled multi-stage screw compressor including a high-stage compressor, a low-stage compressor, and a motor for driving the high-stage compressor and the low-stage compressor.
The direct contact type economizer is a direct contact type double economizer.
The direct contact type double economizer has a high-stage region connected to the high-stage compressor and a low-stage region connected to the low-stage compressor.
The primary refrigerant circuit has a connection circuit that is branched from the low-stage circuit that connects the low-stage region and the low-stage compressor and is connected to the housing of the motor.
The control unit is a refrigerating device that controls the opening degree of the first valve to the first opening degree and opens the second valve when the detection value of the detection unit exceeds the threshold value . A high-stage level sensor that detects the liquid level of the first refrigerant stored inside the high-stage region, and a high-stage level sensor.
Further, a low-stage level sensor for detecting the liquid level of the first refrigerant stored inside the low-stage region is provided.
The first aspect of the present invention, wherein the control unit controls the opening degree of the first valve to the second opening degree and opens the second valve when the high-stage level sensor or the low-stage level sensor fails. Refrigeration equipment. The refrigerating apparatus according to claim 1 or 2 , wherein the first refrigerant is an NH ₃ refrigerant and the second refrigerant is a CO ₂ refrigerant. A primary refrigerant circuit in which the first refrigerant circulates and a compressor, condenser, expansion valve, and evaporator are arranged.
The secondary refrigerant circuit in which the second refrigerant circulates and is connected to the evaporator and the cooling load,
A direct contact economizer provided in the primary refrigerant circuit between the condenser and the evaporator to supply cooled primary refrigerant gas to the compressor.
A bypass path that branches off from the primary refrigerant circuit on the upstream side of the expansion valve and joins the primary refrigerant circuit on the downstream side of the direct contact economizer.
A first valve provided in the primary refrigerant circuit and adjusting the amount of the first refrigerant flowing into the direct contact economizer.
A second valve provided in the bypass path and adjusting the amount of the first refrigerant flowing into the bypass path,
It has a detector for detecting the pressure of the first refrigerant circulating in the primary refrigerant circuit or the pressure or temperature of the second refrigerant circulating in the secondary refrigerant circuit.
The compressor is an oil-cooled multi-stage screw compressor including a high-stage compressor, a low-stage compressor, and a motor for driving the high-stage compressor and the low-stage compressor.
The direct contact type economizer is a direct contact type double economizer.
The direct contact type double economizer has a high-stage region connected to the high-stage compressor and a low-stage region connected to the low-stage compressor.
The primary refrigerant circuit is a method of using a refrigerating apparatus having a connection circuit branched from the low-stage circuit connecting the low-stage region and the low-stage compressor and connected to the housing of the motor. hand,
A method of using a freezing device that controls the opening degree of the first valve to the first opening degree and opens the second valve when the detection value of the detection unit exceeds a threshold value.

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