JP5469835B2 - Ammonia refrigeration equipment - Google Patents

Description

  The present invention relates to an ammonia refrigeration apparatus comprising a refrigeration cycle using ammonia as a refrigerant.

  Conventionally, chlorofluorocarbon has been used as a refrigerant in a refrigeration apparatus, but ammonia has been reviewed as a substitute for chlorofluorocarbon in order to prevent destruction of the ozone layer and global warming and protect the global environment.

  However, since ammonia is corrosive and hygroscopic, it enters the motor chamber in which the motor that drives the compressor of the refrigeration apparatus is housed, and dissolves the coating of the stator and rotor windings of the motor. It may cause peeling and cause short circuit, burnout, or disconnection of the winding.

  The ammonia refrigeration apparatus shown in FIG. 4 has a two-stage screw compressor body 3 driven by a motor 2 connected to a power source 1, an oil separator / recoverer 4, a condenser 5, an expansion valve 6, and an evaporator 7. Of the compressor body 3, check valves 9 and 10 are provided on the suction side and the discharge side of the compressor body 3, and an electromagnetic valve 11 is provided between the condenser 5 and the expansion valve 6. Oil is supplied to an oil supply portion of the compressor body 3 through an oil passage 13 having an oil cooler 12.

  During operation of the ammonia refrigeration apparatus, the discharge port of the compressor body 3 to the expansion valve 6 are in a high pressure state of, for example, 1.5 MPa (equivalent saturation temperature 40 ° C.), and the suction port of the compressor body 3 from the expansion valve 6. Up to, for example, a low pressure state of 0.1 MPa (equivalent saturation temperature −33 ° C.). When the compressor body 3 stops, high-pressure ammonia gas from the discharge port of the compressor body 3 to the discharge side check valve 10 flows back to the suction side check valve 9. As a result, between the suction side check valve 9 and the discharge side check valve 10, an intermediate pressure state of, for example, 0.7 MPa (equivalent saturation temperature 14 ° C.) is obtained. In this intermediate pressure state, when the ambient temperature becomes 14 ° C. or less, which is the equivalent saturation temperature, the ammonia gas in the motor chamber of the compressor body 3 is liquefied and comes into contact with the stator windings of the motor 2 and corrodes.

Therefore, in Patent Document 1, a liquid reservoir or a liquid reservoir is provided in the lower part of the motor chamber, and the winding of the stator is disposed in the gas phase region of the ammonia refrigerant so as not to contact the liquid phase region. Proposed.
Japanese Utility Model Publication No. 6-17354

  However, even in the prior art of the cited document 1, when the ammonia gas in the gas phase region is liquefied, the liquefied ammonia liquid may come into contact with the stator windings and cause the above-mentioned problems.

  Therefore, an object of the present invention is to provide an ammonia refrigeration apparatus that is excellent in corrosion resistance and electrical insulation, because the ammonia refrigerant that has entered the motor chamber does not liquefy.

In order to solve the above-mentioned problem, the first means is:
A refrigeration apparatus having a compressor body driven by a motor, a condenser, an expansion valve and an evaporator, comprising a refrigeration cycle using ammonia as a refrigerant, and provided with check valves on the suction side and the discharge side of the compressor body. In
An electromagnetic valve provided between the condenser and the expansion valve, which is opened when the compressor body is in operation and closed when the compressor is stopped;
Pressure detecting means for detecting the pressure in the motor chamber of the compressor body;
Temperature detecting means for detecting the temperature in the motor chamber of the compressor body;
Based on the pressure and temperature detected by the pressure detection means and the temperature detection means when the compressor body is stopped, it is determined whether the ammonia gas in the motor chamber is in a liquefied state or not. There is provided temperature adjusting means for raising the temperature in the motor chamber to a temperature equal to or higher than the saturated saturation temperature of the ammonia refrigerant when it is in a liquefied state.

  In the first means configured as described above, if the ammonia gas is liquefied in the motor chamber when the operation of the compressor body is stopped, the temperature in the motor chamber is increased by the temperature adjusting means. Does not liquefy. As a result, ammonia gas in the motor chamber does not liquefy and come into contact with the stator windings.

  The second means is the first means, wherein the temperature adjusting means comprises a jacket surrounding the motor chamber and means for supplying a heating fluid to the jacket. According to this configuration, it is possible to prevent liquefaction of ammonia gas with a simple structure using an existing jacket.

  According to the invention of the first means, when the operation of the compressor body is stopped, the temperature in the motor chamber can be raised by the temperature adjusting means, so that the ammonia gas in the motor chamber is liquefied and becomes a winding of the stator. No contact, corrosion resistance and electrical insulation are improved.

  According to the invention of the second means, since the temperature of the ammonia gas in the motor chamber can be adjusted by the jacket surrounding the motor chamber, the liquefaction of the ammonia gas can be prevented with a simple structure.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows an ammonia refrigerating apparatus according to a first embodiment of the present invention. In this ammonia refrigeration apparatus, a temperature sensor 38 and a pressure sensor 39 are provided in the motor casing 20, and based on the detected temperature and detected pressure from these sensors 38 and 39, the control device 17 supplies heating fluid to the jacket 25 when operation is stopped. Except for the supply, it is substantially the same as the conventional ammonia refrigerating apparatus shown in FIG. 4, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The heated fluid is supplied from the hot water source 40 to the jacket 25 via the pump 41. The heating fluid is not limited to hot water, and ammonia refrigerant or the like exiting the evaporator 5 can be used.

  FIG. 2 shows a detailed sectional view of the compressor body 3 of the ammonia refrigeration apparatus. The compressor body 3 includes a motor 2, a first stage compression unit 18, and a second stage compression unit 19, which are accommodated in casings 20, 21, and 22.

  The motor 2 includes a rotor 23 and a stator 24, and a jacket 25 is formed in the motor casing 20 so as to surround the outer surface thereof. Cooling water or refrigerant liquid is supplied to the jacket 25 during operation of the compressor body 3.

  The first stage compression section 18 includes a pair of male and female screw rotors 26 and 27 that are rotatably supported and mesh with each other. The male rotor 26 has a rotor shaft 28 at one end formed integrally with the output shaft of the motor 2 and is driven by the motor 2. A first stage suction port 29 communicating with the evaporator 5 is formed on the motor side of the casing 21 of the first stage compression unit 18, and a first stage discharge port 30 is formed on the opposite side. A suction-side check valve 9 is provided in the first stage suction port 29.

  The second stage compression section 19 is composed of a pair of male and female screw rotors 31 and 32 that are rotatably supported and mesh with each other. The male rotor 31 has a rotor shaft 33 at one end connected to a discharge-side rotor shaft 34 of the male rotor 26 of the first stage compression unit 18 via a coupling 35 so as to be integrally rotatable. A second suction port 36 communicating with the first-stage discharge port 30 is formed on the first-stage compression section 18 side of the male rotor 31 and the female rotor 32 of the second-stage compression section 19, and oil separation and recovery is formed on the opposite side. A second-stage discharge port 37 communicating with the container 4 is formed.

  The operation of the ammonia refrigerator having the above configuration will be described. During operation, the solenoid valve 11 is opened, and the first stage compression unit 18 and the second stage compression unit 19 are driven by the motor 2. The ammonia refrigerant sucked from the suction port 29 is compressed by the first stage compression unit 18 and the second stage compression unit 19, and is discharged from the discharge port 37 to the oil separation and recovery device 4. In the oil separator / collector 4, the lubricating oil contained in the compressed ammonia gas is separated and stored downward. The ammonia gas separated by the oil separator / recovery unit 4 passes through the discharge side check valve 10 and reaches the condenser 5 where it is condensed. The condensed ammonia refrigerant passes through the electromagnetic valve 11, is decompressed by the expansion valve 8, reaches the evaporator 7, evaporates here, and returns to the suction port 29 of the compressor body 3 through the suction check valve 9. The lubricating oil separated by the oil separator / recovery unit 4 is supplied to the closed space of the compressor body 3, a bearing, and the like via the oil flow path 13.

  When the compressor body 3 is stopped, the electromagnetic valve 11 is closed. As a result, high-pressure ammonia gas from the discharge port 37 of the compressor body 2 to the discharge-side check valve 10 flows back to the suction-side check valve 9, and from the suction-side check valve 9 to the discharge-side check valve 10. For example, the intermediate pressure state is 0.7 MPa (equivalent saturation temperature 14 ° C.). Here, the control device 17 monitors the detected temperature and detected pressure from the temperature sensor 38 and the pressure sensor 39. FIG. 3 shows the relationship between the temperature and pressure in the motor casing 20, and ammonia gas is liquefied when the state is above the curve in FIG.

  Therefore, based on the detected temperature and the detected pressure detected by the temperature sensor 38 and the pressure sensor 39, the control device 17 determines whether or not the ammonia gas in the motor casing 20 is in a state of being liquefied at a temperature equal to or lower than the saturation temperature. If the ammonia gas in the motor casing 20 is liquefied, the pump 41 is activated and the hot water from the hot water source 40 is supplied into the jacket 25. Thereby, since the inside of the motor casing 25 is maintained at a temperature equal to or higher than the saturation temperature, the ammonia gas inside the motor casing 20 does not liquefy. For this reason, the coil | winding of the stator 24 of the motor 2 does not contact ammonia liquid, and corrosion resistance increases.

1 is an overall configuration diagram of an ammonia refrigeration apparatus according to a first embodiment of the present invention. Sectional drawing of the compressor main body of the ammonia refrigerating apparatus of FIG. The figure which shows the relationship between the temperature in a motor casing, and a pressure. The whole ammonia refrigeration equipment block diagram.

Explanation of symbols

2 Motor 3 Compressor Body 5 Condenser 6 Expansion Valve 7 Evaporator 9 Suction Side Check Valve 10 Discharge Side Check Valve 11 Solenoid Valve 17 Controller 23 Rotor 24 Stator 25 Jacket 38 Temperature Sensor 39 Pressure Sensor 40 Hot Water Source 41 pump

Claims (2)

A refrigeration apparatus having a compressor body driven by a motor, a condenser, an expansion valve and an evaporator, comprising a refrigeration cycle using ammonia as a refrigerant, and provided with check valves on the suction side and the discharge side of the compressor body. In
An electromagnetic valve provided between the condenser and the expansion valve, opened when the compressor body is in operation , and closed when stopped;
Pressure detecting means for detecting the pressure in the motor chamber of the compressor body;
Temperature detecting means for detecting the temperature in the motor chamber of the compressor body;
Based on the pressure and temperature detected by the pressure detection means and the temperature detection means when the compressor body is stopped, it is determined whether the ammonia gas in the motor chamber is in a liquefied state or not. An ammonia refrigeration apparatus comprising temperature adjusting means for raising the temperature in the motor chamber to a temperature equal to or higher than a saturated saturation temperature of the ammonia refrigerant when in a liquefied state.   2. The ammonia refrigeration apparatus according to claim 1, wherein the temperature adjusting means includes a jacket surrounding the motor chamber and means for supplying a heating fluid to the jacket.

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