JP2019211170A - Refrigeration cycle device - Google Patents

Abstract

To solve the problem that erosion occurs in contact with a disc wheel of a second or subsequent stage by a coolant liquid in an injection passage flowing from a composition plane between the disc wheel and a rotary shaft to the back face of the disc wheel.SOLUTION: A velocity type compressor 3a of a refrigeration cycle device 1a comprises: a rotor 7 including a rotary shaft 5 and multiple impellers 6 fixed to the rotary shaft 5; a bearing 8 rotatably supporting the rotary shaft 5; a main passage 11 extending inside of the rotary shaft 5 from an inflow port 10 to an intake port of the compressor in a rotation axis direction; an injection passage 14 extending from a branch port which is branched from the main passage 11, to an outflow port 13 formed on a wall surface 12 of a coolant steam passage in which coolant steam flows on a surface of the impeller 6; and a disc wheel back face drain line 18. The injection channel 14 crosses a composition plane between the impeller 6 and the rotary shaft 5, and the disc wheel back face drain line 18 is connected to the composition plane and the outside of the velocity type compressor 3a.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a refrigeration cycle apparatus including a cooling mechanism for vapor compression.

  Conventionally, this type of refrigeration cycle apparatus includes a two-stage compressor, and is configured to cool the refrigerant vapor discharged from the first-stage compressor before the second-stage compressor sucks (for example, Patent Document 1).

  FIG. 5 shows a conventional refrigeration cycle apparatus described in Patent Document 1. As shown in FIG. As shown in FIG. 5, a refrigeration cycle apparatus 100 in which a centrifugal compressor 101 and a Roots compressor 102 are provided in series is described. The centrifugal compressor 101 is provided at the front stage, and the Roots compressor 102 is provided at the rear stage.

  The refrigeration cycle apparatus 100 further includes an evaporator 103, a circulation pump 104, a pipe 105, a load 106, a pipe 107, a condenser 108, a steam duct 109, and a steam cooler 110. The evaporator 103 evaporates the evaporating liquid such as water by boiling in a reduced pressure state lower than the atmospheric pressure. Water whose temperature has been lowered by boiling evaporation in the evaporator 103 is pumped out by the circulation pump 104, sent to the load 106 through the pipe line 105, and supplied for cooling. The saturated vapor generated in the evaporator 103 is first sucked into the centrifugal compressor 101 and compressed. Next, the steam compressed by the centrifugal compressor 101 is sucked and compressed by the Roots compressor 102 and then guided to the condenser 108.

  The steam cooler 110 is provided in a portion of the steam duct 109 between the centrifugal compressor 101 and the roots compressor 102. The steam cooler 110 cools the steam compressed by the centrifugal compressor 101 from the superheated steam state to the saturated steam state, or close to the saturated steam state. The cooling is performed by spraying water directly on the steam or indirectly exchanging heat between the steam and atmospheric air or cooling water.

JP 2008-122012 A

  In the conventional configuration, the suction superheat degree of the roots compressor (second stage compressor) can be reduced, while the centrifugal compressor (first stage compressor) and the roots compressor (second stage compressor) are reduced. ) Heat generated in the compressor process could not be removed, and the compressor power due to the increase in enthalpy during compression could not be reduced. Therefore, a pressure pump and piping necessary for spraying the refrigerant liquid are configured by centrifugally pressurizing the refrigerant liquid in the injection flow path inside the rotating body that rotates at a high speed of the compressor and injecting the refrigerant liquid into the refrigerant vapor flow path. Since the refrigerant vapor in the overheated state is continuously cooled without increasing the number of components such as the above, it is possible to suppress the increase in enthalpy during compression and reduce the compressor power.

  However, since the injection flow path intersects with the joint surface between the impeller of the compressor and the rotary shaft, the refrigerant liquid that flows through the injection flow path flows from the joint surface to the rear surface of the impeller. The refrigerant liquid in the injection flow path is centrifugally pressurized by the high-speed rotation of the compressor, and the maximum pressure in the injection flow path is, for example, about 1.4 MPa. On the other hand, since the pressure on the rear surface of the impeller of the compressor is close to the low-stage pressure of the refrigeration cycle apparatus, for example, about 1.7 kPa, the high-pressure refrigerant liquid in the injection flow path travels along the joint surface. Then, the refrigerant liquid flows into the rear surface of the low-pressure impeller, and the refrigerant liquid having a coarse droplet diameter flows out into the refrigerant vapor space. Thereby, in the case of the multistage compression configuration, there is a problem that erosion occurs due to contact with the second and subsequent impellers.

  The present disclosure solves the above-described conventional problems, and reduces the compressor power due to the increase in enthalpy during compression, while the refrigerant liquid in the injection passage does not leak from the joint surface to the rear surface of the impeller, and the second stage. An object of the present invention is to provide a refrigeration cycle apparatus that suppresses subsequent erosion of an impeller.

The refrigeration cycle apparatus of the present disclosure includes
An evaporator that evaporates the refrigerant liquid and generates refrigerant vapor;
A speed type compressor that sucks, compresses and discharges refrigerant vapor generated in the evaporator;
A condenser that introduces and condenses the refrigerant vapor discharged from the speed compressor to generate the refrigerant liquid,
The speed compressor is
A rotation axis;
A rotating body including a plurality of impellers fixed to the rotating shaft;
A bearing that rotatably supports the rotating shaft;
Inside the rotating shaft, a main flow path extending in the rotating shaft direction from an inlet formed at an end of the rotating shaft to an inlet of the compressor;
An injection flow path extending from a branch port branched from the main flow path to an outlet formed in a wall surface of the refrigerant vapor flow path through which the refrigerant vapor flows on the impeller surface;
The ejection flow path is in contact with a joint surface between the impeller and the rotating shaft,
A part of the joint surface disposed on the bearing side is a refrigeration cycle apparatus connected to the outside of the speed compressor.

  According to the above aspect, the refrigerant liquid is supplied from the main flow path of the rotating shaft, and is centrifugally pressurized in the injection flow path inside the rotating body that rotates at high speed and injected into the refrigerant vapor flow path. Therefore, the overheated refrigerant vapor is continuously cooled. Will be. At this time, the refrigerant liquid leaking from the joint surface between the first stage impeller and the rotating shaft out of the refrigerant liquid flowing through the injection flow path is drained to the outside of the speed compressor through the joint surface. Thereby, since the refrigerant liquid does not flow into the rear surface of the impeller, erosion of the second and subsequent impellers is suppressed.

  The refrigeration cycle apparatus of the present disclosure can suppress erosion of the second and subsequent impellers without causing the refrigerant liquid in the injection flow channel to leak from the joint surface to the rear surface of the impeller.

Configuration diagram of refrigeration cycle apparatus according to Embodiment 1 of the present disclosure Configuration diagram of speed-type compressor in Embodiment 1 of the present disclosure Sectional view of the speed type compressor along line II in FIG. First modified example of refrigeration cycle apparatus according to Embodiment 1 Configuration diagram of conventional refrigeration cycle equipment

The first aspect of the present disclosure is:
An evaporator that evaporates the refrigerant liquid and generates refrigerant vapor;
A speed type compressor that sucks, compresses and discharges refrigerant vapor generated in the evaporator;
A condenser that introduces and condenses the refrigerant vapor discharged from the speed compressor to generate the refrigerant liquid,
The speed compressor is
A rotation axis;
A rotating body including a plurality of impellers fixed to the rotating shaft;
A bearing that rotatably supports the rotating shaft;
Inside the rotating shaft, a main flow path extending in the rotating shaft direction from an inlet formed at an end of the rotating shaft to an inlet of the compressor;
An injection flow path extending from a branch port branched from the main flow path to an outlet formed in a wall surface of the refrigerant vapor flow path through which the refrigerant vapor flows on the impeller surface;
The ejection flow path is in contact with a joint surface between the impeller and the rotating shaft,
A part of the joint surface disposed on the bearing side is a refrigeration cycle apparatus connected to the outside of the speed compressor.

  According to the above aspect, the refrigerant liquid is supplied from the main flow path of the rotating shaft, and is centrifugally pressurized in the injection flow path inside the rotating body that rotates at high speed and injected into the refrigerant vapor flow path. Therefore, the overheated refrigerant vapor is continuously cooled. Will be. At this time, the refrigerant liquid leaking from the joint surface between the first stage impeller and the rotating shaft out of the refrigerant liquid flowing through the injection flow path is drained to the outside of the speed compressor through the joint surface. Thereby, since the refrigerant liquid does not flow into the rear surface of the impeller, erosion of the second and subsequent impellers is suppressed.

According to a second aspect of the present disclosure, particularly in the refrigeration cycle apparatus according to the first aspect,
A rear boss portion located on the back surface of the impeller and opposite to the steam inlet side in the axial direction is a part of the impeller, and is more axial with respect to the blade end of the hub surface of the impeller. On the steam outlet side,
Inside the speed compressor, there is an impeller drainage line,
The impeller back surface drainage line is a drainage channel connected to the joint surface and the outside of the speed compressor.

  According to the above aspect, the refrigerant liquid leaking from the joint surface is drained to the outside of the speed type compressor through the impeller back surface drain line, and therefore, particularly when the refrigerant liquid spray amount from the injection flow path is large at a high rotation speed. In this case, the refrigerant liquid does not flow into the rear surface of the impeller. Thereby, the erosion of the impellers in the second and subsequent stages is suppressed.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited by the embodiment.

(Embodiment 1)
FIG. 1 is a configuration diagram of a refrigeration cycle apparatus according to the first embodiment of the present disclosure. In FIG. 1, the refrigeration cycle apparatus 1 a includes an evaporator 2, a compressor 3, and a condenser 4.

  The refrigeration cycle apparatus 1a is filled with the same type of refrigerant. As the refrigerant charged in the refrigeration cycle apparatus 1a, a chlorofluorocarbon refrigerant such as HCFC (hydrochlorofluorocarbon) and HFC (hydrofluorocarbon), a refrigerant with a low global warming coefficient such as HFO-1234yf, and a natural refrigerant such as CO2 and water are used. be able to. The refrigerant of the refrigeration cycle apparatus 1a is desirably water. When water is used, the cycle pressure ratio becomes large and the degree of superheat of the refrigerant vapor becomes excessive. Therefore, the work to be performed by the compressor 3 can be advantageously reduced by suppressing the enthalpy increase in the compression process.

  The evaporator 2 is comprised by the container which has heat insulation and pressure resistance, for example. The evaporator 2 stores liquid phase refrigerant and evaporates the refrigerant inside by exchanging heat with the outside. The temperature of the liquid-phase refrigerant stored in the evaporator 2 and the temperature of the gas-phase refrigerant generated in the evaporator 2 are 5 ° C., for example. The evaporator 2 may be an indirect heat exchanger such as a shell tube heat exchanger that indirectly exchanges heat between a liquid-phase refrigerant and another heat medium, or a spray type or a filler. It may be a direct contact type heat exchanger such as a formula.

  The compressor 3 sucks and compresses the gas-phase refrigerant generated in the evaporator 2. The compressor 3 is a speed type compressor, for example. The speed type compressor is a compressor that increases the pressure of the refrigerant by giving momentum to the refrigerant and decelerating the speed of the refrigerant. Examples of the speed type compressor (turbo compressor) include a centrifugal compressor, a mixed flow compressor, and an axial flow compressor. The compressor 3 may include a mechanism for changing the rotation speed, such as a motor driven by an inverter. The temperature of the refrigerant at the discharge port of the compressor 3 is, for example, 100 ° C to 150 ° C.

  The condenser 4 is comprised by the container which has heat insulation and pressure resistance, for example. The condenser 4 stores the liquid-phase refrigerant and condenses the refrigerant vapor inside by exchanging heat with the outside. The temperature of the refrigerant vapor introduced into the condenser 4 is 100 ° C. to 150 ° C., and the temperature of the gas-phase refrigerant condensed in the condenser 4 is, for example, 35 ° C. The condenser 4 may be an indirect heat exchanger such as a shell tube heat exchanger that indirectly exchanges heat between a liquid-phase refrigerant and another heat medium, or a spray type or a filler. It may be a direct contact type heat exchanger such as a formula.

  Next, the compressor 3 will be described in detail.

  FIG. 2 shows a configuration diagram of the speed compressor 3a.

  In FIG. 2, the speed compressor 3 a includes a rotating body 7 including a rotating shaft 5 and a plurality of impellers 6, a bearing 8, an inlet 10 formed on a surface 9 of the rotating shaft, a main flow path 11, the rotating body 7, and a refrigerant. A wall surface 12 of the steam channel, an outlet port 13, and an injection channel 14 are provided. A rear boss portion 16 is provided on the back surface of the impeller 6. Furthermore, the impeller back surface drain line 18 is provided inside the speed type compressor 3a.

  The rotating body 7 includes a plurality of impellers 6 and a rotating shaft 5, and the impeller 6 and the rotating shaft 5 are fixed by shrinkage fitting or tension bolts as separate parts.

  The impeller 6 is connected to the rotary shaft 5 and rotates at high speed. The number of rotations is, for example, 5000 rpm to 100,000 rpm. The impeller 6 is made of, for example, aluminum, duralumin, iron, ceramic, or the like, and gives a rotational speed to the refrigerant vapor flowing through the refrigerant vapor flow path.

  The rotating shaft 5 is connected to the impeller 6 and rotates the impeller 6 by rotating at high speed. The number of rotations is, for example, 5000 rpm to 100,000 rpm. The rotating shaft 5 is made of a strong iron-based material such as S45CH.

  The bearing 8 supports the rotating shaft 5 to be rotatable. The bearing 8 may be a ball bearing or a sliding bearing, but a sliding bearing lubricated with the refrigerant of the refrigeration cycle apparatus 1a is desirable. The bearing 8 is connected to the compressor casing directly or through a bearing box (not shown).

  The inflow port 10 is opened on the surface 9 of the rotating shaft and communicates with the main flow path 11.

  The surface 9 of the rotating shaft may be an end surface of the rotating shaft 5 or a side surface of the rotating shaft 5.

  The main flow path 11 extends in the axial direction of the rotary shaft 5 and communicates with the inlet 10 and the injection flow path 14. The main flow path 11 is preferably formed at the axis of the rotary shaft 5, but may be formed at a radial position close to the axis. The main channel 11 has a diameter of, for example, 0.017 m, and the main channel 11 has an axial length of, for example, 0.09 m. The main channel 11 is a passage for supplying the refrigerant liquid to the injection channel 14. The main flow path 11 extends in the direction of the rotation axis from the inlet 10 formed at the end of the rotation shaft 5 to the suction port of the compressor.

  The outflow port 13 is an opening provided in the wall 7 of the rotating body 7 and the refrigerant vapor flow path, and communicates with the injection flow path 14. The wall surface 12 of the refrigerant vapor channel may be any surface among the side surface of the rotating shaft 5, the hub surface of the impeller 6, and the blade surface of the impeller 6.

  The impeller 6 has a rear boss portion 16 provided on the bearing side with respect to the axial direction from the blade tip 17 of the hub surface of the impeller 6. The impeller 6 and the rotating shaft 5 are fitted so that the impeller 6 is rotated by the rotating shaft 5. A surface where the impeller 6 and the rotating shaft 5 are in contact is referred to as a contact surface 31.

  The contact surface 31 between the rear boss portion 16 and the rotary shaft 5 is located on the steam outlet side with respect to the axial direction from the blade tip 17 of the hub surface of the impeller 6.

  As shown in FIG. 2, the injection flow path 14 extends from the branch port 30 branched from the main flow path 11 to the outlet 13 formed on the wall surface 12 of the refrigerant vapor flow path through which the refrigerant vapor flows on the surface of the impeller 6. Yes. Since the injection flow path 14 crosses the contact surface 31, the refrigerant liquid in the injection flow path 14 leaks from the contact surface 31 to the rear surface of the impeller. As a result, erosion of the second and subsequent impellers occurs.

  Moreover, the speed type compressor 3a is a multistage compressor, and the injection flow path 14 is formed in the impeller 6 of each stage.

  The impeller back surface drainage line 18 is a drainage channel that discharges the refrigerant liquid leaking from the contact surface 31 to the outside of the speed compressor 3a. As shown in FIG. 2, the impeller back surface drain line 18 is provided, for example, in a support flange 19 that is in contact with the inner wall of the speed type compressor 3 a and supports the rotating body 7. On the other hand, it extends vertically downward.

  Of the refrigerant liquid flowing through the injection flow path 14, the refrigerant liquid leaked from the joint surface flows into the impeller back surface drain line 18 connected to the joint surface, and is finally sent to the outside of the speed compressor 3a. As a result, erosion of the second and subsequent impellers can be suppressed by the impeller rear drain line 18 without the refrigerant liquid in the injection flow channel leaking from the joint surface to the impeller rear surface.

  FIG. 3 is a sectional view of the speed compressor 3a taken along the line II of FIG.

  The rotating body 7 is supported by a support flange 19 inside the speed type compressor 3a. The refrigerant vapor compressed by the first stage compressor is sent to the second stage compressor through the refrigerant vapor channel 15.

  The operation and action of the refrigeration cycle apparatus 1a and speed compressor 3a configured as described above will be described below.

  When the refrigeration cycle apparatus 1a is left for a certain period (for example, at night), the temperature is approximately equal to room temperature. First, when the compressor 3 is started, the refrigerant vapor pressure in the evaporator 2 decreases, and refrigerant vapor is generated by absorbing heat from the outside air. Refrigerant vapor generated in the evaporator 2 is sucked into the compressor 3, boosted and discharged. The high-pressure refrigerant vapor discharged from the compressor 3 is introduced into the condenser 4 and is condensed by radiating heat to the outside air to become a refrigerant liquid.

  A refrigerant liquid for cooling the refrigerant vapor is supplied from the inlet 10 and branches to the injection flow path 14 through the main flow path 11 of the rotating shaft 5. The refrigerant liquid is centrifugally pressurized in the injection flow path 14 inside the rotating body that rotates at high speed, is injected from the outlet 13 into the refrigerant vapor flow path, and is sucked together with the refrigerant vapor sucked into the compressor 3. When the refrigerating capacity is 880 kW as the rated condition, the spray amount of the refrigerant liquid necessary for removing the heat generated in the compressor process is, for example, 0.034 kg / s, and the diameter of the injection flow path 14 is, for example, 0. If the number of nozzles is 13 mm and the number of nozzles is 16, the injection flow path 14 is injected from the outlet 13 to the refrigerant vapor flow path at a pressure of about 1.4 MPa.

  As described above, in the present embodiment, the refrigerant liquid is centrifugally pressurized in the injection flow path 14 inside the rotating body that rotates at a high speed and injected into the refrigerant vapor flow path, so that the overheated refrigerant vapor is continuously cooled. At this time, of the refrigerant liquid flowing through the injection flow path, the refrigerant liquid leaking from the joint surface between the first stage impeller and the rotating shaft is passed through the impeller back surface drain line 18 to the speed type. Since the water is discharged to the outside of the compressor 3a, the refrigerant liquid does not flow into the rear surface of the impeller even when the amount of the refrigerant liquid sprayed from the injection flow path 14 is large at a high rotation speed. As a result, erosion of the second and subsequent impellers can be suppressed.

(Embodiment 2)
FIG. 4 is a first modification of the speed compressor 3a according to the first embodiment of the present disclosure shown in FIG. As shown in FIG. 4, the speed compressor 3 b includes a bearing water supply line 20, a bearing drain line 21, and a bearing space 22 inside the speed compressor 3 a as a modification of the first embodiment. It is configured.

  About the speed type compressor 3b comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  In the speed type compressor 3b, the bearing 8 is a sliding bearing lubricated with the refrigerant liquid of the refrigeration cycle apparatus 1a. A bearing water supply line 20 is provided inside the rotary shaft 5, and the bearing water supply line 20 is connected to the bearing space 22 between the rotary shaft 5 and the bearing 8 and the main flow path 11.

  On the other hand, the bearing drain line 21 is connected to the bearing space 22 and the outside of the speed compressor 3b. That is, the bearing water supply line 20 and the bearing drain line 21 are connected via the bearing space 22. A part of the refrigerant liquid flowing through the main flow path 11 is supplied as a lubricating fluid from the bearing water supply line 20 to the bearing space 22 and finally sent from the bearing drainage line 21 to the outside of the speed compressor 3b. . The pressure of the main flow path 11 is, for example, 0.1 MPa, and the bearing space 22 is, for example, 1.5 kPa.

  The rear boss portion 16 is provided on the steam outlet side with respect to the axial direction from the blade tip 17 of the hub surface of the impeller 6, and further on the steam outlet side of the joint surface between the rotating shaft 5 and the impeller 6. One end of the joint surface is connected to the bearing space 22. That is, among the refrigerant liquid flowing through the injection flow path 14, the refrigerant liquid leaked from the joint surface between the rotating shaft 5 and the impeller 6 flows into the bearing space 22 connected to the joint surface, and serves as a lubricating fluid for the bearing 8. Works. The refrigerant liquid leaked from the joint surface and the refrigerant liquid supplied from the bearing water supply line 20 as a lubricating fluid are mixed in the bearing space 22 and finally sent from the bearing drain line 21 to the outside of the speed compressor 3b. . That is, the bearing drainage line 21 plays the role of the impeller backside drainage line 18 in the speed type compressor 3a. At this time, the pressure at the intersection of the joint surface and the injection flow path 14 is, for example, about 0.5 MPa, and the bearing space 22 is, for example, about 1.5 kPa. Further, the pressure on the rear surface of the impeller is, for example, about 1.7 kPa. Even if a minute space exists between the bearing space 22 and the rear surface of the impeller, the refrigerant liquid in the bearing space 22 is transferred to the rear surface of the impeller. Do not flow.

  As described above, in the present embodiment, the refrigerant liquid leaking from the joint surface flows into the bearing space 22 and acts as a lubricating fluid for the bearing 8, and then from the bearing drain line 21 to the outside of the speed compressor 3b. Drained. Thereby, the erosion of the impellers in the second and subsequent stages is suppressed without increasing the impeller rear drain line 18.

  As described above, the refrigeration cycle apparatus according to the present disclosure can generate cold with high efficiency by which the compression power can be reduced by continuously reducing the increase in enthalpy during compression. Therefore, it can be applied to applications such as central air conditioners in buildings and chillers for process cooling.

DESCRIPTION OF SYMBOLS 1a Refrigeration cycle apparatus 2 Evaporator 3a-3b Speed type compressor 4 Condenser 5 Rotating shaft 6 Impeller 7 Rotating body 8 Bearing 9 Rotating shaft surface 10 Inlet port 11 Main channel 12 Rotating body and wall surface of refrigerant vapor channel 13 Outlet port DESCRIPTION OF SYMBOLS 14 Injection flow path 15 Refrigerant vapor flow path 16 Back boss | hub part 17 Blade tip 18 Impeller back surface drain line 19 Support flange 20 Bearing water supply line 21 Bearing drain line 22 Bearing space 100 Refrigeration cycle apparatus 101 Centrifugal compressor 102 Roots type compressor DESCRIPTION OF SYMBOLS 103 Evaporator 104 Circulation pump 105 Pipe line 106 Load 107 Pipe line 108 Condenser 109 Steam duct 110 Steam cooler

Claims (2)

An evaporator that evaporates the refrigerant liquid and generates refrigerant vapor;
A speed type compressor that sucks, compresses and discharges refrigerant vapor generated in the evaporator;
A condenser that introduces and condenses the refrigerant vapor discharged from the speed compressor to generate the refrigerant liquid,
The speed compressor is
A rotation axis;
A rotating body including a plurality of impellers fixed to the rotating shaft;
A bearing that rotatably supports the rotating shaft;
Inside the rotating shaft, a main flow path extending in the rotating shaft direction from an inlet formed at an end of the rotating shaft to an inlet of the compressor;
An injection flow path extending from a branch port branched from the main flow path to an outlet formed in a wall surface of the refrigerant vapor flow path through which the refrigerant vapor flows on the impeller surface;
The ejection flow path is in contact with a joint surface between the impeller and the rotating shaft,
A part of the joint surface arranged on the bearing side is connected to the outside of the speed compressor,
Refrigeration cycle equipment. The refrigeration cycle apparatus is further positioned on the bearing side of the impeller hub surface blade tip with respect to the rotation axis direction, and on the back surface of the impeller, a rear boss portion that is a part of the impeller;
An impeller back surface drain line disposed inside the speed type compressor and connected to a part of the joint surface and the outside of the speed type compressor;
The refrigeration cycle apparatus according to claim 1.

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