JP2018119750A - Turbo refrigerator - Google Patents

Abstract

A lubricating oil flowing from a gear casing of a compressor to a pressure equalizing tube accompanying a refrigerant gas during operation of a turbo refrigerator is separated from the refrigerant gas, and the separated lubricating oil extends downward from a bottom of the pressure equalizing tube. Provided is a centrifugal chiller that can be collected by a branch pipe. A turbo compressor (1) for compressing a refrigerant and a gear casing (11) provided in the turbo compressor (1) for storing lubricating oil, and lubricating oil is supplied to a sliding portion including a bearing of the turbo compressor (1). In a centrifugal chiller configured to collect lubricating oil after lubrication at the lower portion of the gear casing 11, the gear is connected to the gear casing 11 and a suction passage pipe 5a provided on the suction side of the turbo compressor 1. The pressure equalizing pipe 14 for equalizing the pressure in the casing 11 to the pressure on the suction side of the turbo compressor 1, and a branch pipe 15 branched from the middle of the pressure equalizing pipe 14 and extending downward from the bottom of the pressure equalizing pipe 14. [Selection diagram] Fig. 1

Description

  The present invention relates to a turbo chiller, and more particularly, to a turbo chiller configured to collect lubricating oil in a sliding portion including a bearing of a turbo compressor and collect the lubricating oil after being lubricated in a lower portion of a gear casing. Is.

  The turbo refrigerator includes a turbo compressor that is a high-speed rotating body. The turbo compressor has a built-in bearing that supports the high-speed rotating body and a speed increaser that transmits torque to the high-speed rotating body. Since heat generated in the bearings and the gearboxes is equivalent to mechanical loss, it is essential to supply lubricating oil to the compressor in order to lubricate the bearings and gearboxes and to cool the bearings and gearboxes. . Therefore, an oil tank is provided below the gear casing of the compressor, and the lubricating oil in the oil tank is supplied to the bearing and the speed increaser by the oil pump.

JP 2009-186028 A

In the above turbo compressor, in order to make it easy for the lubricating oil supplied to the bearings and the like to return to the oil tank by maintaining the oil tank provided at the lower part of the gear casing in a low pressure atmosphere, the suction of the gear casing and the turbo compressor A pressure equalizing pipe is connected to a suction passage pipe provided on the side to equalize the pressure in the gear casing to the suction side pressure of the turbo compressor.
Thus, the turbo compressor is provided with a pressure equalizing pipe that connects the gear casing and the suction passage pipe provided on the suction side of the turbo compressor, so that some lubrication occurs during the operation of the turbo refrigerator. Oil is entrained with the refrigerant gas from the gear casing through the pressure equalizing pipe to the suction passage pipe. As a result, there is a problem that the lubricating oil does not return to the oil tank below the original gear casing but flows to the evaporator and the liquid level of the oil tank is lowered.

  The present invention has been made in view of the above circumstances, and separated and separated the lubricant oil flowing from the gear casing of the compressor to the pressure equalizing pipe accompanying the refrigerant gas during operation of the turbo refrigerator. An object of the present invention is to provide a turbo chiller capable of recovering lubricating oil by a branch pipe extending downward from the bottom of the pressure equalizing pipe.

  To achieve the above object, one aspect of the present invention includes a turbo compressor that compresses a refrigerant, and a gear casing that is provided in the turbo compressor and stores lubricating oil, and includes a bearing of the turbo compressor. In the centrifugal chiller configured to collect the lubricating oil after lubricating the sliding portion by supplying the lubricating oil to the lower portion of the gear casing, the suction provided on the suction side of the gear casing and the turbo compressor A pressure equalizing pipe for connecting the road pipe to equalize the pressure in the gear casing to the suction side pressure of the turbo compressor, and a branch pipe branched from the middle of the pressure equalizing pipe and extending downward from the bottom of the pressure equalizing pipe It is characterized by comprising.

In a preferred aspect of the present invention, the lower end of the branch pipe is connected to the gear casing provided in the turbo compressor, or to an oil tank provided separately from the gear casing.
In a preferred aspect of the present invention, the connection location to the separately installed oil tank is a portion higher than the liquid level of the oil tank.
In a preferred aspect of the present invention, there is provided an oil pump that supplies lubricating oil in the gear casing provided in the turbo compressor or in an oil tank separately from the gear casing to the sliding portion. Features.
In a preferred aspect of the present invention, the inner diameter of the pressure equalizing pipe is set so that the flow velocity of the fluid flowing in the pressure equalizing pipe is a predetermined value or less.

In a preferred aspect of the present invention, the fluid is a mixed fluid composed of a refrigerant gas and lubricating oil, and the flow velocity is a predetermined value when the refrigerant gas and the lubrication are mixed before the mixed fluid reaches the branch pipe. It is characterized by a flow rate at which oil can be separated.
A preferred aspect of the present invention includes a plurality of turbo compressors connected in series, parallel, or series-parallel for compressing refrigerant gas, and the gear casings respectively provided in the plurality of turbo compressors, and the series, parallel, or series Of the plurality of turbo compressors connected in parallel, the suction path pipe having the lowest pressure is connected by the pressure equalizing pipe.
In a preferred aspect of the present invention, the branch pipe branched from the pressure equalizing pipe is provided corresponding to each of the plurality of turbo compressors.

In a preferred aspect of the present invention, the branch pipe is provided on the downstream side of the joining point where the fluids flowing out from the gear casings provided in the plurality of turbo compressors are joined by the pressure equalizing pipe.
In a preferred aspect of the present invention, the lower ends of the branch pipes of the plurality of turbo compressors are connected to one oil tank separately from the gear casing.

  According to the present invention, during operation of the centrifugal chiller, the lubricating oil accompanying the refrigerant gas and flowing from the gear casing of the compressor to the pressure equalizing pipe is separated from the refrigerant gas, and the separated lubricating oil is separated from the bottom of the pressure equalizing pipe. It can collect | recover with the branch pipe extended below. Therefore, it is possible to prevent the oil level of the lubricating oil stored in the oil tank at the lower part of the gear casing or the oil tank separate from the gear casing from being lowered.

FIG. 1 is a schematic diagram showing a first embodiment of a turbo refrigerator according to the present invention. FIG. 2 is a schematic view showing a second embodiment of the turbo refrigerator according to the present invention. FIG. 3 is a schematic diagram showing a turbo refrigerator having a configuration in which three turbo compressors are connected in series and parallel.

Hereinafter, embodiments of a turbo refrigerator according to the present invention will be described with reference to FIGS. 1 to 3. 1 to 3, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.
FIG. 1 is a schematic diagram showing a first embodiment of a turbo refrigerator according to the present invention. As shown in FIG. 1, a turbo refrigerator includes a turbo compressor 1 that compresses refrigerant, a condenser 2 that cools and compresses the compressed refrigerant gas with cooling water (cooling fluid), and cold water (cooled fluid). ), The evaporator 3 which evaporates the refrigerant and exhibits the refrigeration effect, and the economizer 4 which is an intermediate cooler disposed between the condenser 2 and the evaporator 3.

  The turbo compressor 1, the condenser 2, the economizer 4, and the evaporator 3 are connected by a refrigerant pipe 5 through which the refrigerant circulates. An orifice is provided in the refrigerant pipe 5 that connects the condenser 2 and the economizer 4, and an orifice is provided in the refrigerant pipe 5 that connects the economizer 4 and the evaporator. Of the refrigerant pipes 5 connecting the evaporator 3 and the turbo compressor 1, the refrigerant pipe provided on the suction side of the turbo compressor 1 is referred to as a suction passage pipe 5a.

  The turbo compressor 1 is composed of a multistage turbo compressor having a plurality of impellers. The turbo compressor 1 is connected to the economizer 4 by a refrigerant pipe 5, and the refrigerant gas separated by the economizer 4 is introduced into an intermediate portion of the multi-stage compression stage (two stages in this example) of the turbo compressor 1. It is like that. The turbo compressor 1 includes a gear casing 11 that accommodates a bearing and a speed increaser, and an oil tank 12 for supplying oil to the bearing and the speed increaser is provided below the gear casing 11. An oil pump 13 is installed in the lower part of the gear casing 11, and the lubricating oil in the oil tank 12 is supplied to the bearings and the speed increaser in the gear casing 11 through the oil supply pipe 16 by the oil pump 13. It is like that. In order to equalize the pressure in the gear casing 11 to the suction side pressure of the turbo compressor 1 by connecting the gear casing 11 and the suction passage pipe 5 a provided on the suction side of the turbo compressor 1 to the turbo compressor 1. Pressure equalizing pipe 14 is installed. By maintaining the oil tank 12 provided below the gear casing 11 in a low-pressure atmosphere by the pressure equalizing pipe 14, the lubricating oil supplied to the bearings and the speed increaser is easily returned to the oil tank 12.

  In the refrigeration cycle of the turbo chiller configured as shown in FIG. 1, the refrigerant circulates through the turbo compressor 1, the condenser 2, the economizer 4, and the evaporator 3, and chilled water is generated by the cold heat source obtained by the evaporator 3. The amount of heat from the evaporator 3 that is manufactured and corresponds to the load and taken into the refrigeration cycle and the amount of heat corresponding to the work of the turbo compressor 1 supplied from the motor 13 are released to the cooling water supplied to the condenser 2. Is done. On the other hand, the refrigerant gas separated by the economizer 4 is introduced into an intermediate portion of the multistage compression stage of the turbo compressor 1, merges with the refrigerant gas from the first stage impeller, and is compressed by the second stage impeller. According to the two-stage compression single stage economizer cycle, since the refrigeration effect by the economizer 4 is added, the refrigeration effect is increased by that amount, and the efficiency of the refrigeration effect can be improved compared to the case where the economizer 4 is not installed. it can.

As shown in FIG. 1, the turbo compressor 1 is provided with a pressure equalizing pipe 14 that connects the gear casing 11 and a suction passage pipe 5 a provided on the suction side of the turbo compressor 1. During this operation, a part of the lubricating oil is entrained together with the refrigerant gas from the gear casing 11 through the pressure equalizing pipe 14 to the suction passage pipe 5a. As a result, there is a problem that the lubricating oil does not return to the oil tank 12 below the original gear casing 11 but flows into the evaporator 3 and the liquid level of the oil tank 12 is lowered.
Therefore, in the present invention, as shown in FIG. 1, a branch pipe 15 that branches from the middle of the pressure equalizing pipe 14 and extends downward from the bottom of the pressure equalizing pipe 14 is provided. The lower end of the branch pipe 15 is connected to a portion higher than the liquid level of the oil tank 12. Connecting to a portion lower than the liquid level of the oil tank 12 is not preferable because the lower end of the branch pipe 15 becomes a part of the oil tank 12 and the amount of oil retained in the oil tank 12 increases. The inner diameter of the pressure equalizing tube 14 is set so that the flow velocity of the fluid flowing in the pressure equalizing tube 14 is not more than a predetermined value, for example, 3 m / sec or less if the refrigerant is HFC-245fa and its lubricating oil. As a result, gas-liquid separation of the fluid flowing in the pressure equalizing pipe 14 is promoted, and the lubricating oil is separated downward by gravity so as to flow under the pressure equalizing pipe 14. There are several refrigerants, and there are also some lubricating oils. Since there are several combinations of the refrigerant and the lubricating oil, the predetermined value of the flow velocity of the fluid flowing in the pressure equalizing pipe 14 may be appropriately determined by experiment according to the combination. When the lubricating oil flows through the lower part of the pressure equalizing pipe 14 and reaches the branch pipe 15, the lubricating oil flows down through the branch pipe 15 and returns to the oil tank 12 provided at the lower part of the gear casing 11 to prevent outflow from the gear casing. In addition, the liquid level of the oil tank 12 can be prevented from being lowered. The branch pipe 15 may be connected to a separate oil tank from the gear casing 11 and may be connected to the separate oil tank, whichever is connected in consideration of workability and piping length. You just have to decide.

  As described above, according to the present invention, the lubricating oil that flows along with the refrigerant gas and flows from the gear casing 11 of the compressor to the pressure equalizing pipe 14 during the operation of the turbo refrigerator is separated from the refrigerant gas, and the separated lubricating oil is obtained. Can be recovered by the branch pipe 15 extending downward from the bottom of the pressure equalizing pipe 14. Therefore, it is possible to prevent the oil level of the lubricating oil stored in the oil tank 12 below the gear casing 11 or the oil tank separate from the gear casing from being lowered.

  The lubricating oil used in the turbo compressor 1 slightly leaks into the refrigerant system through a shaft seal mechanism (not shown) and dissolves in the refrigerant. The leaked lubricating oil accumulates in the liquid phase refrigerant in the evaporator 3 having the lowest pressure. In order to recover the lubricating oil contained in the refrigerant from the evaporator 3, an oil recovery mechanism including an ejector 17 is provided. The evaporator 3 is connected to an ejector 17 through an oil recovery pipe 18. The oil recovery pipe 18 is provided with a heater 21 for heating a refrigerant liquid containing lubricating oil. A driving gas supply pipe 19 branches from a refrigerant pipe 5 that connects the turbo compressor 1 and the condenser 2, and the driving gas supply pipe 19 is connected to an ejector 17. The discharge port of the ejector 17 is connected to the gas phase portion in the lower portion of the gear casing 11 through the mixed fluid recovery pipe 20.

  In the oil recovery mechanism configured as shown in FIG. 1, the high-pressure refrigerant gas compressed by the turbo compressor 1 passes through the ejector 17, thereby forming a negative pressure in the ejector 17, and lubricating the evaporator 3. The refrigerant liquid containing oil is sucked into the ejector 17. The refrigerant liquid containing the lubricating oil sucked into the ejector 17 is introduced into the heater 21 through the oil recovery pipe 18 and heated by the refrigerant gas (driving gas) passing through the driving gas supply pipe 19. As a result, the refrigerant liquid is vaporized while the lubricating oil remains in the liquid phase. The heated lubricating oil and the vaporized refrigerant (that is, refrigerant gas) are introduced into the ejector 17 and mixed with the refrigerant gas (driving gas) and transferred to the lower portion of the gear casing 11 of the turbo compressor 1 through the mixed fluid recovery pipe 20. Is done. The same applies to a turbo refrigerator in which turbo compressors for compressing refrigerant gas are connected in parallel to increase the refrigerating capacity.

  FIG. 2 is a schematic view showing a second embodiment of the turbo refrigerator according to the present invention. As shown in FIG. 2, the turbo chiller includes a first turbo compressor 1-1 and a second turbo compressor 1-2 that compress refrigerant gas in multiple stages, and cooling water (cooling) Between the condenser 2 and the evaporator 3, the condenser 2 that cools and condenses with the fluid), the evaporator 3 that takes heat away from the brine (cooled fluid) and evaporates the refrigerant to exert the refrigeration effect. And an economizer 4 that is an intermediate cooler that is connected to each other by a refrigerant pipe 5 through which a refrigerant circulates. Of the refrigerant pipes 5 connecting the evaporator 3 and the first turbo compressor 1-1, the refrigerant pipe provided on the suction side of the first turbo compressor 1-1 is referred to as a suction passage pipe 5a.

  The first turbo compressor 1-1 and the second turbo compressor 1-2 that compress the refrigerant gas in multiple stages are connected in series via an economizer 4. That is, the low-temperature and low-pressure refrigerant gas discharged from the evaporator 3 is compressed by the first turbo compressor 1-1, and the refrigerant gas discharged from the first turbo compressor 1-1 is passed through the economizer 4. It is led to the second turbo compressor 1-2, and further compressed by the second turbo compressor 1-2 to be a high-temperature and high-pressure refrigerant gas.

The first turbo compressor 1-1 and the second turbo compressor 1-2 are provided with gear casings 11-1 and 11-2 for housing bearings and gearboxes, respectively. First oil tanks 12-1 and 12-2 are provided below 11-2. The gear casings 11-1 and 11-2 are connected to the suction passage pipe 5a provided on the suction side of the first turbo compressor 1-1 so that the pressure in the gear casings 11-1 and 11-2 is first. A pressure equalizing pipe 14 for equalizing the suction side pressure of the turbo compressor 1-1 is installed. By maintaining the first oil tanks 12-1 and 12-2 provided below the gear casings 11-1 and 11-2 in a low pressure atmosphere by the pressure equalizing pipe 14, the pressure equalizing pipe 14 is supplied to the bearings and the speed increaser. The lubricating oil is easily returned to the first oil tanks 12-1 and 12-2. Here, when the multistage compressors according to the present embodiment are connected in series, the amount of oil leaking from the gear casing varies depending on the difference in internal pressure of each gear casing, so there is a difference in the liquid level in the gear casing. This causes problems such as a decrease in the liquid level of one of the gear casings. In order to eliminate this, the oil tanks 12-1 and 12-2 communicate with the second oil tank 22 through the oil communication pipes 24 and 25, and the manual valves V 1 and V 2 are connected to the pipes extending from the respective gear casings to the pressure equalizing pipe 14. The liquid levels of the oil tanks 12-1 and 12-2 may be made substantially the same by providing V2 and adjusting the opening of the manual valves V1 and V2.
As described above, the gear casing is used for the purpose of adjusting the liquid level of the oil tanks 12-1 and 12-2 and preventing the lubricating oil supplied to the gear casing from flowing out of the gear casing through the impeller shaft and the speed increaser shaft. The suction passage pipe connected by the pressure equalizing pipe is connected to the suction passage pipe having the lowest pressure.

  In the refrigeration cycle of the low-temperature turbo refrigerator configured as shown in FIG. 2, the first turbo compressor 1-1, the second turbo compressor 1-2, the condenser 2, the evaporator 3, and the economizer 4 are provided. The refrigerant circulates, and the brine is cooled to a low temperature (−5 ° C. to −25 ° C.) by the evaporator 3 to cope with the load, and is supplied from the compressor motor and the amount of heat from the evaporator 3 taken into the refrigeration cycle. The amount of heat corresponding to the work of the turbo compressors 1-1 and 1-2 is released to the cooling water supplied to the condenser 2. On the other hand, the gas refrigerant separated by the economizer 4 merges with the gas refrigerant from the first turbo compressor 1-1 and is compressed by the second turbo compressor 1-2. According to the economizer cycle, since the refrigeration effect portion by the economizer 4 is added, the refrigeration effect is increased by that amount, and the efficiency of the refrigeration effect can be increased as compared with the case where the economizer 4 is not installed.

As shown in FIG. 2, the first turbo compressor 1-1 and the second turbo compressor 1-2 have suction of the gear casings 11-1 and 11-2 and the first turbo compressor 1-1. Since the pressure equalizing pipe 14 connected to the suction passage pipe 5a provided on the side is installed, some lubricating oil passes through the pressure equalizing pipe 14 from the gear casings 11-1 and 11-2 during the operation of the turbo refrigerator. It will be accompanied with the refrigerant gas to the suction pipe 5a. As a result, the lubricating oil does not return to the first oil tanks 12-1 and 12-2 below the original gear casings 11-1 and 11-2, but flows to the evaporator 3 etc. There exists a problem that the liquid level of -1,12-2 falls. In particular, in the case of a low-temperature turbo chiller as shown in FIG. 2, two or more compressors are connected in series, but if two are connected, the leakage of lubricating oil to the suction port of the compressor is doubled. When the temperature becomes low, the pressure of the evaporator 3 becomes low, and the suction pressure of the ejector decreases, so that there is a problem that the amount of recovered lubricating oil decreases.
Therefore, in the turbo chiller shown in FIG. 2, two branch pipes 15-1 and 15-2 that branch from the middle of the pressure equalizing pipe 14 and extend downward from the bottom of the pressure equalizing pipe 14 are installed. The lower end of the branch pipe 15-1 is connected to a portion higher than the liquid level of the oil tank 12-1 of the first turbo compressor 1-1. The lower end of the branch pipe 15-2 is connected to a portion higher than the liquid level of the oil tank 12-2 of the second turbo compressor 1-2. When connected to a portion lower than the liquid level of the oil tanks 12-1 and 12-2, the lower ends of the branch pipes 15-1 and 15-2 become part of the oil tanks 12-1 and 12-2, and the oil tank 12-1 , 12-2 is not preferable because the oil holding amount increases. The inner diameter of the pressure equalizing tube 14 is set so that the flow velocity of the fluid flowing in the pressure equalizing tube 14 is not more than a predetermined value, for example, 3 m / sec or less if the refrigerant is HFC-245fa and its lubricating oil. As a result, gas-liquid separation of the fluid flowing in the pressure equalizing pipe 14 is promoted, and the lubricating oil is separated downward by gravity so as to flow under the pressure equalizing pipe 14. There are several refrigerants, and there are also some lubricating oils. Since there are several combinations of the refrigerant and the lubricating oil, the predetermined value of the flow velocity of the fluid flowing in the pressure equalizing pipe 14 may be appropriately determined by experiment according to the combination. When the lubricating oil flows under the pressure equalizing pipe 14 and reaches the branch pipes 15-1 and 15-2, the lubricating oil flows down through the branch pipes 15-1 and 15-2 and below the gear casings 11-1 and 11-2. Returning to the first oil tanks 12-1 and 12-2 provided in, the outflow to the outside of the gear casing can be prevented, and the liquid level of the oil tanks 12-1 and 12-2 can be prevented from being lowered.

  As described above, according to the present invention, the lubricating oil accompanying the refrigerant gas flowing from the compressor gear casings 11-1 and 11-2 to the pressure equalizing pipe 14 during operation of the turbo refrigerator is separated from the refrigerant gas. The separated lubricating oil can be recovered by the branch pipes 15-1 and 15-2 extending downward from the bottom of the pressure equalizing pipe 14. Accordingly, the oil level of the lubricating oil stored in the first oil tanks 12-1 and 12-2 or the second oil tank 22 provided separately from the gear casings 11-1 and 11-2 at the lower part of the gear casing. Can be prevented.

  The lubricating oil used in the first turbo compressor 1-1 and the second turbo compressor 1-2 is slightly leaked into the refrigerant system through a shaft seal mechanism (not shown) and is dissolved in the refrigerant. The leaked lubricating oil accumulates in the liquid phase refrigerant in the evaporator 3 having the lowest pressure. In order to recover the lubricating oil contained in the refrigerant from the evaporator 3, an oil recovery mechanism including an ejector 17 is provided. The evaporator 3 is connected to an ejector 17 through an oil recovery pipe 18. The oil recovery pipe 18 is provided with a heater 21 for heating a refrigerant liquid containing lubricating oil. A driving gas supply pipe 19 branches from a refrigerant pipe 5 that connects the first turbo compressor 1-1 and the economizer 4. The driving gas supply pipe 19 is connected to an ejector 17. The discharge port of the ejector 17 is connected to the lower part of the gear casing 11-1 of the first turbo compressor 1-1 through the mixed fluid recovery pipe 20.

  In the oil recovery mechanism configured as shown in FIG. 2, the high-pressure refrigerant gas compressed by the first turbo compressor 1-1 passes through the ejector 17, thereby forming a negative pressure in the ejector 17 and evaporating. The refrigerant liquid containing the lubricating oil in the vessel 3 is sucked into the ejector 17. The refrigerant liquid containing the lubricating oil sucked into the ejector 17 is introduced into the heater 21 through the oil recovery pipe 18 and heated by the refrigerant gas (driving gas) passing through the driving gas supply pipe 19. As a result, the refrigerant liquid is vaporized while the lubricating oil remains in the liquid phase. The heated lubricating oil and the vaporized refrigerant (i.e., refrigerant gas) are introduced into the ejector 17 and mixed with the refrigerant gas (driving gas), and the gear casing of the first turbo compressor 1-1 through the mixed fluid recovery pipe 20. It is transferred to the lower part of 11-1.

  As shown in FIG. 2, the first oil tank 12-1 provided below the gear casings 11-1 and 11-2 in the first turbo compressor 1-1 and the second turbo compressor 1-2. , 12-2, a second oil tank 22 is disposed. The second oil tank 22 is not built in the compressor, and is installed independently of the compressor. The first oil tank 12-1 and the second oil tank 22 of the first turbo compressor 1-1 are connected by an oil communication pipe 24. Accordingly, the lubricating oil in the first oil tank 12-1 of the first turbo compressor 1-1 flows into the second oil tank 22 through the oil communication pipe 24. The first oil tank 12-2 and the second oil tank 22 of the second turbo compressor 1-2 are connected by an oil communication pipe 25. Accordingly, the lubricating oil in the first oil tank 12-2 of the second turbo compressor 1-2 flows into the second oil tank 22 via the oil communication pipe 25.

  The second oil tank 22 is provided with a first oil pump 31 for pumping the lubricating oil to the bearing of the first turbo compressor 1-1 and the speed increaser. The second oil tank 22 is provided with a second oil pump 32 for pumping the lubricating oil to the bearings of the second turbo compressor 1-2 and the speed increaser. The gas outlet 22 a of the second oil tank 22 and the gas inlet 11 a of the gear casing 11-1 of the first turbo compressor 1-1 are connected by a gas communication pipe 26. The gas communication pipe 26 is connected to a position above the highest liquid level of the first oil tank 12-1. Therefore, the refrigerant gas dissolved in the lubricating oil is returned to the space above the oil reservoir of the first oil tank 12-1 via the gas communication pipe 26, and the second oil tank 22 is It is configured to be always filled with lubricating oil. The gas communication pipe 26 is set to have a flow path cross-sectional area that is larger than that of the refrigerant gas that can be discharged into the oil when the refrigerator is started. As a result, the oil pressure in the oil communication pipe 24 and the oil communication pipe 25 is not interrupted, and the indentation pressure is applied to the suction ports of the first oil pump 31 and the second oil pump 32 by the weight of the oil. Even if the pressures of 11-1 and 11-2 are reduced, it is possible to prevent cavitation from occurring in the oil pumps 31 and 32.

According to the turbo chiller shown in FIG. 2, the first oil tank 12-1 built in the first turbo compressor 1-1 and the first oil tank 12 built in the second turbo compressor 1-2. -2 is installed at a position below -2, the first oil tank 12-1 and the second oil tank 22 are connected by an oil communication pipe 24, and the first oil tank The tank 12-2 and the second oil tank 22 are connected by an oil communication pipe 25. The first oil pump 31 is disposed in the second oil tank 22, the lubricating oil is supplied to the first turbo compressor 1-1 by the first oil pump 31, and the second oil tank 22 is supplied with the lubricating oil. A second oil pump 32 is provided, and the second oil pump 32 supplies lubricating oil to the second turbo compressor 1-2. Thus, since the hydraulic pressure due to the weight of the lubricating oil is applied to the suction ports of the oil pumps 31 and 32 by the amount that the installation position of the second oil tank 22 is lowered, the NPSH required for the oil pumps 31 and 32 is reduced. Can be secured. Accordingly, there is no performance degradation such as generation of cavitation in the pump, and oil can be supplied to the sliding portion such as the bearing of the compressor without any problem.
In FIG. 2, the lower ends of the branch pipes 15-1 and 15-2 are connected to the lower portions of the gear casings 11-1 and 11-2, but the lower ends of the branch pipes 15-1 and 15-2 are connected to the second oil tank. 22 may be connected.

Next, a turbo chiller including a plurality of turbo compressors connected in series, parallel, or series-parallel (a combination of series and parallel) will be described.
FIG. 3 is a schematic diagram showing a turbo refrigerator having a configuration in which three turbo compressors are connected in series and parallel. As shown in FIG. 3, the turbo refrigerator includes a first turbo compressor 1-1, a second turbo compressor 1-2, and a third turbo compressor 1-3 that compress refrigerant gas in multiple stages, A condenser 2 that cools and compresses the compressed refrigerant gas with hot water or cooling water (cooling fluid), and an evaporator 3 that takes heat from brine or cold water (cooled fluid) and evaporates the refrigerant to exert a refrigeration effect. And an economizer 4 that is an intermediate cooler disposed between the condenser 2 and the evaporator 3, and these devices are connected by a refrigerant pipe 5 through which a refrigerant circulates. Of the refrigerant pipes 5 connecting the evaporator 3 and the first turbo compressor 1-1 and the second turbo compressor 1-2, the first turbo compressor 1-1 and the second turbo compressor 1 are connected. The refrigerant pipe provided on the -2 suction side is referred to as a suction passage pipe 5a.

  As shown in FIG. 3, the first turbo compressor 1-1 and the second turbo compressor 1-2 are connected in parallel to the economizer 4, and the first turbo compressor 1-1 and the second turbo compressor 1-2 are connected to each other. The turbo compressor 1-2 is connected in parallel for the purpose of increasing the refrigeration capacity. That is, the low-temperature and low-pressure refrigerant gas discharged from the evaporator 3 is guided in parallel to the first turbo compressor 1-1 and the second turbo compressor 1-2 via the intake passage pipes 5a and 5a branched. The refrigerant gas is compressed by the compressors 1-1 and 1-2. The first turbo compressor 1-1, the second turbo compressor 1-2, and the third turbo compressor 1-3 are connected in series via the economizer 4. That is, the refrigerant gas compressed by the first turbo compressor 1-1 and the refrigerant gas compressed by the second turbo compressor 1-2 are passed through the economizer 4 to the third turbo compressor 1-3. Then, it is further compressed by the third turbo compressor 1-3 to be a high-temperature and high-pressure refrigerant gas.

The first turbo compressor 1-1, the second turbo compressor 1-2, and the third turbo compressor 1-3 are gear casings 11-1, 11-2 that house bearings and gearboxes, respectively. 11-3, and first oil tanks 12-1, 12-2, 12-3 are provided below the gear casings 11-1, 11-2, 11-3. The gear casings 11-1, 11-2, and 11-3 are connected to the suction passage pipe 5a provided on the suction side of the first turbo compressor 1-1 and the second turbo compressor 1-2. A pressure equalizing pipe 14 for equalizing the pressure in the gear casings 11-1, 11-2, 11-3 to the suction side pressure of the first turbo compressor 1-1, the second turbo compressor 1-2 is installed. Has been. The pressure equalizing pipe 14 maintains the first oil tanks 12-1, 12-2, 12-3 provided in the lower portions of the gear casings 11-1, 11-2, 11-3 in a low pressure atmosphere. In addition, the lubricating oil supplied to the speed increaser is easily returned to the first oil tanks 12-1, 12-2, 12-3. Here, when the multistage compressors according to the present embodiment are connected in series and parallel, the amount of oil leaking from the gear casing varies depending on the difference in internal pressure of each gear casing, so there is a difference in the liquid level in the gear casing. And a problem such as a drop in the liquid level of any gear casing occurs. In order to solve this problem, the oil tanks 12-1, 12-2, 12-3 communicate with the second oil tank 22 through the oil communication pipes 24, 25, 27, and reach the pressure equalizing pipe 14 from each gear casing. By providing manual valves V1, V2, and V3 in the piping and adjusting the opening degree of the manual valves V1, V2, and V3, the liquid levels of the oil tanks 12-1, 12-2, and 12-3 are almost the same. It may be.
Thus, the liquid level adjustment of the oil tanks 12-1, 12-2, and 12-3 and the purpose of preventing the lubricating oil supplied to the gear casing from flowing out of the gear casing through the impeller shaft and the speed increaser shaft. Thus, the suction path pipe connected to the gear casing by the pressure equalizing pipe is connected to the suction path pipe having the lowest pressure.

  In the turbo refrigerator shown in FIG. 3, three branch pipes 15-1, 15-2, and 15-3 branch from the middle of the pressure equalizing pipe 14 and extend downward from the bottom of the pressure equalizing pipe 14. The lower end of the branch pipe 15-1 is connected to a portion higher than the liquid level of the oil tank 12-1 of the first turbo compressor 1-1. The lower end of the branch pipe 15-2 is connected to a portion higher than the liquid level of the oil tank 12-2 of the second turbo compressor 1-2. The lower end of the branch pipe 15-3 is connected to a portion higher than the liquid level of the oil tank 12-3 of the third turbo compressor 1-3. When connected to the lower part of the liquid level of the oil tanks 12-1, 12-2, 12-3, the lower ends of the branch pipes 15-1, 15-2, 15-3 are oil tanks 12-1, 12-2, 12 -3, and the oil holding amount of the oil tanks 12-1, 12-2, 12-3 increases, which is not preferable. The inner diameter of the pressure equalizing tube 14 is set so that the flow velocity of the fluid flowing in the pressure equalizing tube 14 is not more than a predetermined value, for example, 3 m / sec or less if the refrigerant is HFC-245fa and its lubricating oil. As a result, gas-liquid separation of the fluid flowing in the pressure equalizing pipe 14 is promoted, and the lubricating oil is separated downward by gravity so as to flow under the pressure equalizing pipe 14. There are several refrigerants, and there are also some lubricating oils. Since there are several combinations of the refrigerant and the lubricating oil, the predetermined value of the flow velocity of the fluid flowing in the pressure equalizing pipe 14 may be appropriately determined by experiment according to the combination. When the lubricating oil flows under the pressure equalizing pipe 14 and reaches the branch pipes 15-1, 15-2, 15-3, the lubricating oil flows down the branch pipes 15-1, 15-2, 15-3, and the gear casing 11 -1, 11-2, 11-3, returned to the first oil tanks 12-1, 12-2, 12-3 provided at the bottom of the oil casing 12-1 to prevent the oil tank 12-1 from flowing out of the gear casing. , 12-2, 12-3 can be prevented from lowering the liquid level.

  As described above, according to the present invention, the lubricating oil accompanying the refrigerant gas flowing from the gear casings 11-1, 11-2, 11-3 of the compressor to the pressure equalizing pipe 14 during the operation of the turbo chiller can be obtained. The lubricant oil separated from the refrigerant gas can be recovered by the branch pipes 15-1, 15-2, 15-3 extending downward from the bottom of the pressure equalizing pipe 14. Therefore, the first oil tanks 12-1, 12-2, 12-3 or the gear casings 11-1, 11-2, 11-3 below the gear casings 11-1, 11-2, 11-3 Can prevent the oil level of the lubricating oil stored in the separate oil tank 22 from being lowered. Also in the present embodiment, an oil recovery mechanism including an ejector 17 is provided in order to recover the lubricating oil contained in the refrigerant from the evaporator 3. The evaporator 3 is connected to an ejector 17 through an oil recovery pipe 18. The oil recovery pipe 18 is provided with a heater 21 for heating a refrigerant liquid containing lubricating oil. A driving gas supply pipe 19 branches from a refrigerant pipe 5 that connects the first turbo compressor 1-1 and the economizer 4. The driving gas supply pipe 19 is connected to an ejector 17. The discharge port of the ejector 17 is connected to the lower part of the gear casing 11-1 of the first turbo compressor 1-1 through the mixed fluid recovery pipe 20.

  As shown in FIG. 3, gear casings 11-1, 11-2, 11-3 in the first turbo compressor 1-1, the second turbo compressor 1-2, and the third turbo compressor 1-3. A second oil tank 22 is disposed below the first oil tanks 12-1, 12-2, 12-3 provided at the lower part of the first oil tank 12-1. The second oil tank 22 is not built in the compressor, and is installed independently of the compressor. The first oil tank 12-1 and the second oil tank 22 of the first turbo compressor 1-1 are connected by an oil communication pipe 24. The first oil tank 12-2 and the second oil tank 22 of the second turbo compressor 1-2 are connected by an oil communication pipe 25. The first oil tank 12-3 and the second oil tank 22 of the third turbo compressor 1-3 are connected by an oil connecting pipe 27. The gas discharge port 22a of the second oil tank 22 and the gas inlet 11a of the gear casing 11-2 of the second turbo compressor 1-2 are connected by a gas communication pipe 26. Accordingly, the refrigerant gas dissolved in the lubricating oil is returned to the space above the oil reservoir of the first oil tank 12-2 via the gas communication pipe 26, and the second oil tank 22 is It is configured to be always filled with lubricating oil. The second oil tank 22 includes a bearing for the first turbo compressor 1-1, a first oil pump 31 for pumping lubricating oil to the speed increaser, and a bearing for the second turbo compressor 1-2. And a second oil pump 32 for pumping the lubricating oil to the gearbox, a bearing for the third turbo compressor 1-3, and a third oil pump 33 for pumping the lubricant to the gearbox. It is installed.

Thus, the hydraulic pressure due to the weight of the lubricating oil is applied to the suction ports of the oil pumps 31, 32, 33 because the installation position of the second oil tank 22 is lowered downward. Necessary NPSH can be secured. Accordingly, there is no performance degradation such as generation of cavitation in the pump, and oil can be supplied to the sliding portion such as the bearing of the compressor without any problem.
In FIG. 3, the lower ends of the branch pipes 15-1, 15-2, and 15-3 are connected to the lower portions of the gear casings 11-1, 11-2, and 11-3. , 15-3 may be connected to the second oil tank 22.

  Although the embodiment of the present invention has been described so far, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention may be implemented in various different forms within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Turbo compressor 1-1 1st turbo compressor 1-2 2nd turbo compressor 1-3 3rd turbo compressor 2 Condenser 3 Evaporator 4 Economizer 5 Refrigerant piping 5a Suction path pipe 11, 11- 1, 11-2, 11-3 Gear casing 12 Oil tank 12-1, 12-2, 12-3 First oil tank 13 Oil pump 14 Pressure equalizing pipe 15, 15-1, 15-2, 15-3 Branch Pipe 16 Oil supply pipe 17 Ejector 18 Oil recovery pipe 19 Drive gas supply pipe 20 Mixed fluid recovery pipe 21 Heater 22 Second oil tank 24, 25, 27 Oil communication pipe 26 Gas communication pipe 31 First oil pump 32 Second Oil pump 33 Third oil pump V1, V2, V3 Manual valve

Claims (10)

A turbo compressor that compresses the refrigerant, and a gear casing that is provided in the turbo compressor and stores lubricating oil. Lubrication after lubricating the lubricating portion by supplying lubricating oil to a sliding portion including a bearing of the turbo compressor In the turbo refrigerator configured to collect oil in the lower part of the gear casing,
A pressure equalizing pipe for connecting the gear casing and a suction passage pipe provided on the suction side of the turbo compressor to equalize the pressure in the gear casing to the suction side pressure of the turbo compressor;
A turbo chiller comprising: a branch pipe branched from the middle of the pressure equalizing pipe and extending downward from the bottom of the pressure equalizing pipe.   The turbo refrigerator according to claim 1, wherein a lower end of the branch pipe is connected to the gear casing provided in the turbo compressor or to an oil tank provided separately from the gear casing.   The turbo chiller according to claim 2, wherein the connection location to the separate oil tank is a portion higher than the liquid level of the oil tank.   3. An oil pump for supplying lubricating oil in the gear casing provided in the turbo compressor or in an oil tank provided separately from the gear casing to the sliding portion. Turbo refrigerator.   The turbo chiller according to any one of claims 1 to 4, wherein an inner diameter of the pressure equalizing pipe is set so that a flow velocity of the fluid flowing in the pressure equalizing pipe is a predetermined value or less.   The fluid is a mixed fluid composed of refrigerant gas and lubricating oil, and the flow velocity is a predetermined value at which the refrigerant gas and the lubricating oil can be separated before the mixed fluid reaches the branch pipe. The turbo refrigerator according to claim 5, wherein the turbo refrigerator is provided.   A plurality of turbo compressors connected in series, parallel or series-parallel for compressing refrigerant gas, the gear casings respectively provided in the plurality of turbo compressors, and a plurality of turbo connected in series, parallel or series-parallel The turbo refrigerator according to any one of claims 1 to 6, wherein a suction path pipe having the lowest pressure among the compressors is connected by the pressure equalizing pipe.   The turbo refrigerator according to claim 7, wherein the branch pipe branched from the pressure equalizing pipe is provided so as to correspond to each of the plurality of turbo compressors.   The turbo refrigerator according to claim 7, wherein the branch pipe is provided on a downstream side of a joining point where fluids flowing out from gear casings provided in the plurality of turbo compressors are joined by the pressure equalizing pipe.   The turbo chiller according to any one of claims 7 to 9, wherein lower ends of branch pipes of the plurality of turbo compressors are connected to one oil tank separately from the gear casing. .

Images