JP2827801B2 - Turbo refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo refrigerator which uses a refrigerant containing no Cl as a refrigerant and which requires high efficiency and a wide operating range.

[0002]

2. Description of the Related Art CFC11, CFC12, HCFC12
3. Tar using a refrigerant containing Cl group such as HCFC22
In the refrigerating machine, the mineral oil (such as turbine oil) used as the lubricating oil for the compressor has a small amount of moisture absorption even when released to the atmosphere, so that a means for removing moisture in the oil is unnecessary. However, a so-called alternative refrigerant containing no Cl group instead of the above refrigerant, for example, HFC143a (1,1,1,2 tetrafluoroethane) is not compatible with mineral oil and has a turbo refrigerator to separate two phases. Can not use mineral oil.
Therefore, it is indispensable to use a synthetic oil (for example, an ester oil) newly designed in order to have compatibility.

[0003] Improving the reliability of centrifugal compressors for centrifugal chillers,
In terms of cost reduction, the drive motor has been downsized and the distance between bearings of the speed increasing gear shaft has been ensured. However, in order to further reduce cost, it is possible to unitize and shorten the manufacturing process. It is necessary to have a structure. Centrifugal compressors are described in, for example, “Refrigeration Mechanical Engineering Handbook” (Asakura Shoten, 196
5 years) As shown in P305 and Japanese Patent Publication No. 52-42921, the drive motor and the shaft bearing that is divided in the axial direction and directly connected to the motor rotor are partially or entirely disposed in the compressor side casing. It has a structure.

Some centrifugal compressors have a structure in which stationary blades (a plurality of blades) are arranged at equal intervals over the entire circumference of the diffuser on the outer periphery of the impeller. The diffuser flow path is formed between the blades of the stationary blade and the side wall of the diffuser. Is formed. In a low flow rate region at a high rotation speed, a separation region occurs on the negative pressure surface of the stationary blade, and a sufficient pressure rise cannot be obtained. As a result, a so-called turning stall occurs in which the peeling area turns in the circumferential direction first. When the flow rate is further reduced, a decrease in surge occurs. As a technique for moving the surge phenomenon to the low flow rate side, auxiliary wings are arranged on the inner peripheral side between the stationary wings of the stationary wings arranged at equal intervals in the diffuser, and the leading edge side of the stationary wings or auxiliary wings from the side plate side to the core plate There has been proposed a centrifugal compressor inclined in the downstream direction toward the side (Japanese Patent Laid-Open No. 1-247798).

[0005]

However, the above-mentioned synthetic oil has a property that water easily absorbs moisture, and when a large amount of water is mixed in, the synthetic oil is hydrolyzed and the function of the lubricating oil is impaired. . Further, it is unstable with respect to chlorides, and when a large amount of chlorine is mixed therein, the synthetic oil is hydrolyzed, and the function of the lubricating oil is impaired. In general, water is mixed into the lubricating oil because water during the security test using water performed before the operation of the compression refrigerator remains in the machine without being completely removed. The remaining water tends to mix into the synthetic oil.

[0006] In addition, when the compression refrigerator is cleaned using a chlorine-based cleaning agent during assembly, and the cleaning agent is not completely removed after the cleaning, the synthetic oil is unstable with respect to chlorine substances. Synthetic oils are hydrolyzed and accelerated in degradation in the same way as water, and lubricating oils lose their function.

[0007] It is an object of the present invention to provide a turbo refrigerator which removes water or chlorine mixed in synthetic oil and makes it possible to use an alternative refrigerant.

Another object of the present invention is to provide a turbo refrigerator capable of operating without generating a surge phenomenon and a rotating stall even in a low flow rate region.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an evaporator, a condenser, a compressor for compressing refrigerant gas from the evaporator, a drive for driving the compressor, and an oil system for circulating lubricating oil. In a refrigerator, this is achieved by providing a water removal device in the oil system.

According to another aspect of the present invention, there is provided a centrifugal compressor having a diffuser in which a stationary vane is arranged in a diffuser of a compressor and kinetic energy of a fluid discharged from an impeller is converted into pressure energy by the stationary vane. Auxiliary wings in which the leading edge of the stationary blade is inclined in the downstream direction from the side plate side to the core plate side, the chord length is shorter than the stationary blade, and the leading edge is inclined in the downstream direction from the side plate side to the core plate side. , And one of the wing surfaces of the auxiliary wing is arranged on the inner peripheral side of the stationary wing such that the wing surface faces the stationary wing.

Further, in order to achieve the above object, the present invention provides a centrifugal compressor provided with a stationary blade in a diffuser of a compressor, and a diffuser for converting kinetic energy of a discharge fluid of an impeller into pressure energy by the stationary blade. In the diffuser, the leading edge of the stationary blade arranged unevenly in the diffuser is inclined in the downstream direction from the side plate side to the core plate side, the chord length is shorter than the stationary blade, the leading edge is from the side plate side to the core plate side. An auxiliary wing that is inclined in the downstream direction is obtained by arranging a stationary wing on an outer periphery of an impeller arranged on an inner peripheral side of the stationary wing such that one of the wing surfaces of the auxiliary wing faces the stationary wing. .

[0012]

The moisture removing device used for removing moisture is made of a material that absorbs only moisture, and when the lubricant passes through the moisture removing device, only the moisture in the lubricant is collected. Therefore, the moisture in the lubricating oil is removed.

[0013] Since both the stationary blade and the auxiliary blade can have the leading edge on the side plate side closer to the impeller than the conventional one, the flow near the connection direction can be strongly guided toward the stationary blade. As a result, a backflow is unlikely to occur, so that a surge phenomenon does not occur even in a low flow rate region. In addition, since the auxiliary wings were arranged in the coarse part and the dense part with the stationary wings and the blade spacing was unevenly distributed with the auxiliary wings, the stall was initially performed faster in the coarse passages in the wing spacing than in the dense passage. As a result, the passing flow rate of the stalled inter-blade passage becomes smaller than the passing flow rate of the non-stalled inter-blade passage, and the passing flow rate of the non-stalled inter-blade passage is increased by the reduced amount to cause a rotating stall. It becomes difficult.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, a turbo refrigerator has a condenser 1,
Evaporator 2, compressor (turbo compressor) 3, and this compressor 3
And a driving source 5 for driving. The condenser 1 has a built-in heat transfer tube 1A for introducing cooling water from outside to cool the high-temperature and high-pressure refrigerant gas, and the evaporator 2 has a built-in heat transfer tube 2A for taking out cold water to the outside. The condenser 1, the evaporator 2, and the compressor 3 are connected by a refrigerant system 14, and an expansion valve 14A is interposed between the condenser 1 and the evaporator 2. An oil tank 4 for storing lubricating oil is provided below the compressor 3, and an oil pump 6 for lubricating the lubricating oil is provided in the oil tank 4. The lubricating oil system 7 includes the oil pump 6 and the compressor 3
And the drive source 5 to circulate the lubricating oil to the bearings 51A, 51B, 51C. The lubricating oil system 7 is provided with a moisture removing device 8, a moisture detector 9, an oil cooler 10, an oil strainer (filter) 11, partition valves 12, 13, and the like.

FIG. 2 is a detailed view of the water removing device 8. A desiccant 21 is filled in a container 20. Desiccant 21
For example, a molecular sieve (molecular sieve) having pores smaller than the molecular diameter of the refrigerant and having a function of adsorbing moisture is used. The spring 22 is for fixing the desiccant 21 in the container 20.

Although a so-called alternative refrigerant containing no Cl is used as the refrigerant, the present embodiment uses the HFC134a (the same applies to other embodiments described below). Although a synthetic oil is used as the lubricating oil, an ester oil is used in this embodiment (the same applies to other embodiments described below).

Next, the operation of the centrifugal chiller having the above configuration will be described.

The high-temperature and high-pressure refrigerant gas compressed by the compressor 3 is introduced into the condenser 1, where it is cooled by the cooling water flowing through the heat transfer tube 1A and liquefied to become a liquid refrigerant. When passing through the expansion valve 14, the low-temperature and high-pressure liquid refrigerant that has exited the condenser 1 is further lowered in temperature, becomes low-temperature and low-pressure liquid refrigerant, and accumulates in the evaporator 2. Here, for example, when the heat exchange tube 2A exchanges heat with the liquid refrigerant, the liquid refrigerant evaporates to become a refrigerant gas by exchanging heat with the air by the external air-conditioning load and returning the cooled water. This refrigerant gas is compressed by the compressor 3 to become high-temperature and high-pressure refrigerant gas again, introduced into the condenser 1, where it is cooled by the cooling water flowing through the heat transfer tube 1A, liquefied, and a cycle of becoming a liquid refrigerant is repeated. When the oil pump 6 is operated, the lubricating oil passes through the moisture removing device 8, the moisture detector 9, the oil cooler 10, and the oil strainer 11, and the moisture in the lubricating oil is adsorbed when passing through the moisture removing device 8, and the lubricating oil is lubricated. Moisture is removed from the oil.
The water can also be removed by operating the oil pump 6 alone without operating the refrigerator and lubricating the lubricating oil. For example, an indicator whose color changes depending on the moisture content can be used as the moisture detector 9 so that the replacement time of the moisture removal device 8 can be known (otherwise, moisture detection means for notifying the replacement time by an alarm may be used). The oil cooler 10 cools the lubricating oil to prevent the oil temperature from rising.
In addition, the oil strainer 11 removes particulate matter mixed into the oil. Since the replacement of the water removing device 8 is performed with the partition valves 12 and 13 closed, there is no need to recover the refrigerant in the device for the replacement.

FIG. 3 shows a container 20 filled with a moisture removing / strainer 23 in which a desiccant is solidified in order to have a function of removing moisture and removing particulates.

FIG. 4 shows another embodiment of the present invention, which is a turbo refrigerator provided with an automatic oil recovery function. Only parts different from the above-described embodiment will be described.

The lubricating oil branch system 3 branched from the lubricating oil system 7
0 is returned to the oil tank 4. This branch system 30
Is provided with an ejector 31. A refrigerant system 32 is provided below the refrigerant liquid level of the evaporator 2 and near the refrigerant liquid level, and is connected to the oil recovery unit 33. The heater 34 is for heating the refrigerant liquid in the oil recovery unit 33. The recovered oil system 35 is provided at the bottom of the oil recovery unit 33 and is connected to the ejector 31.
It is connected to the. Further, a refrigerant system 36 for recovering the refrigerant is provided above the oil recovery unit 33, and is connected to the refrigerant system 14 between the evaporator 2 and the compressor 3.

The function of the centrifugal chiller having the above configuration is as follows.

In the vicinity of the refrigerant level of the evaporator 2, the lubricating oil leaking from the compressor 3 is dissolved in the refrigerant, and the lubricating oil content in the refrigerant is larger than that at the bottom of the evaporator 2. . From this part, the refrigerant liquid is supplied to the oil recovery device 33 to the refrigerant system 32.
Capture via. In the oil recovery unit 3, the refrigerant gas from the condenser 1 is passed through a pipe 34, and this heat heats the refrigerant liquid in the oil recovery unit 33 to increase the concentration of the lubricating oil. On the other hand, the water mixed in the lubricating oil is sucked up from the oil collecting device 33 by the negative pressure generated in the ejector 31 together with the lubricating oil in the oil collecting device 33, and the water is removed together with the lubricating oil by the water removing device 8 and the water detecting device. In the process of returning to the oil tank 4 via 11, moisture is removed by the moisture removing device 8. The water removing device 8 can be arranged between the oil pump 6 and the ejector 31, between the oil pump 6 and the ejector 31, or between the ejector 31 and the oil collecting device 33, in addition to between the oil strainer 11 and the ejector 31.

According to this embodiment, not only the lubricating oil system 7 but also the water in the refrigerant system 32 can be removed.

Next, the structure of the compressor 3 will be described with reference to FIG. The figure is a longitudinal sectional view of a drive unit of the compressor 3, and the drive unit includes a drive motor 62, a rotor 62a, and a stator 62b. 63 is a first member directly connected to the rotor 62a.
The first shaft 63 has a gear 63a fitted to a shaft end of the rotor 62a opposite to the motor. The first shaft 63 is supported by bearings 65-1 and 65-2. The bearings 65-1 and 65-2 are mounted on a bearing support frame 60a formed integrally with the motor casing 60. Reference numeral 64 denotes a second pinion having a pinion 64a meshed with the speed increasing gear 63a, and an impeller 64b attached thereto.
Axis. The second shaft 64 has bearings 66-1, 66-
2, and these bearings 66-1 and 66-2 are mounted on a bearing support frame 68 of the gear casing 61. The gear casing 61 includes a flange portion 61 a for attaching the motor casing 60 and a motor casing 6.
An opening 61b is provided for inserting the speed-increasing gear 63a into the gear casing 61 when the 0 is attached. Reference numeral 67 denotes an oil supply hole for supplying lubricating oil to the bearings 65-1, 65-2 and the bearings 66-1, 66-2.

Next, the operation of assembling the driving section will be described.

First, the motor unit is assembled by mounting the stator 62b and the bearings 65-1 and 65-2 on the motor casing 60.
Attach. Next, the first shaft 6 fitted with the rotor 62a
3 is assembled in the direction of the bearing 65-1 from the mounting side of the bearing 65-2, and the speed increasing gear 63a is further fitted. In this state, the motor unit is completed. In the unit test of the motor, a test collar may be attached instead of the speed increasing gear 63a.

Each bearing is lubricated through the lubrication hole 67 in the state of the motor unit, and a rotation test of the motor is performed. Disassembly of the rotating body after the test is completed is unnecessary.

Next, the second shaft 64 and the bearings 66-1, 6
The motor unit is assembled in the gear casing 61 in which 6-2 is incorporated. In this case, the speed increasing gear 63a is mounted so as to mesh with the counterpart pinion 64a through the opening 61b provided in the gear casing 61. The relative positional accuracy between the first shaft 63 and the second shaft 64 is determined by a spigot provided on the flange 61 a of the motor casing 60.

The assembly is completed by the above assembly work.

Next, the diffuser of the centrifugal compressor will be described with reference to FIGS.

FIG. 6 is a sectional view of the centrifugal compressor viewed from the direction of the rotation axis of the impeller, FIG. 7 is a sectional view of a diffuser portion, and FIG.
FIG. 3 is a layout diagram of stationary wings and auxiliary wings. In the drawing, a so-called diffuser is provided between the impeller 1 and the casing 5, and converts the kinetic energy of the flow flowing out of the impeller 71 into pressure. At the leading edge of the stationary blade 72, an attached stationary blade 7 whose height is equal to or smaller than the stationary blade 72 and whose leading edge is inclined downstream from the side plate 77 side to the core plate 78 side.
3 are integrally formed. Further, an auxiliary wing 74 having a smaller chord length and height than the stationary wing 72 is provided between the wings of the plurality of stationary wings 72, and only one of the wing surfaces is the stationary wing 72.
And a so-called vaned diffuser. The leading edge of the auxiliary wing 74 is inclined downstream from the side plate 77 side to the core plate 78 side. The plurality of stationary blades 72 and the auxiliary blades 74 form a casing 75 in a flow path forming a scroll shape (including a scroll in which the spiral flow path gradually narrows or a collector in which the spiral flow path is uniform).
Are coarsely arranged in the vicinity of the tongue 76 (within about one-half of the entire circumference), and are densely arranged in the vicinity other than the vicinity of the tongue 76. Further, when the auxiliary wing 74 is disposed only in the portion other than the vicinity of the tongue portion 76 (within about one-half of the entire circumference) of the stationary wing 72, the result of preventing the rotating stall is further improved.

When the operating flow rate of the compressor is large, the flow flowing out of the impeller 71 is divided into the stationary blade 72, the attached stationary blade 73,
The stationary wing 7 flows at an angle close to the entrance angle of the auxiliary wing 74.
In the passage between the two, the kinetic energy of the flow is efficiently converted to pressure. At this time, since only one wing surface of the auxiliary wing 74 is arranged so as to face the stationary wing 72, the passage between the stationary wings 72 is not narrowed by the auxiliary wing 74, so that the kinetic energy of the flow Is converted to pressure with high efficiency. When the operating flow rate of the compressor decreases, the impeller 1
Flows from the stationary blade 72, the attached stationary blade 73, and the auxiliary blade 74 at an angle in a direction away from the radial direction of the impeller 1 more than the entrance angle. For this reason, there is a strong tendency that the flow does not follow the stationary blade 2 which strongly converts the kinetic energy of the flow into pressure. This tendency is remarkable on the side plate 77 side. If the flow does not follow the stationary blade 72, a part of the flow will flow backward, causing a stall, making it difficult to convert kinetic energy into pressure, and causing unsteady phenomena such as a rotating stall, surging, and the operation of the compressor. Becomes difficult. The attached stationary blade 73 controls the flow on the side plate 77 side of the leading edge of the stationary blade 72
2, the auxiliary wing 74 guides the flow intermediate the stationary wing 72 toward the stationary wing 72. Thus, the attached stationary vane 7
3. Since the flow near the leading edge of the stationary blade 72 is strongly guided toward the stationary blade 72 by the action of both the auxiliary blade 74, the occurrence of stall is suppressed. Therefore, unsteady phenomena such as turning stall and surging hardly occur, and the operating range of the compressor in the low flow rate region can be expanded. In order to further expand the operating range of the compressor in the low flow rate range, it is necessary to prevent the rotating stall. Rotating stall is a phenomenon that occurs when the flow rate is larger than surging. Some of the stationary blades 72 stall and the stall moves in the circumferential direction. Becomes difficult. In a centrifugal compressor having a scroll flow path, the pressure at the diffuser outlet at a low flow rate is not uniform in the circumferential direction. The pressure is high near the tongue 76 and low on the opposite side. Therefore, the stationary blade 2 near the tongue 6 is more likely to stall than the stationary blade 2 on the opposite side. Excluding the attached stationary blade 73 of the stationary blade 72 near the tongue 76, the stationary blade 72 near the tongue 76 is more likely to stall than the stationary blade 72 on the opposite side. Therefore, the stationary wing 72 near the tongue 76
In the case of the stall, the stationary blade 72 on the opposite side does not stall even if the stall occurs, so that the circumferential movement of the stall hardly occurs and the turning stall is suppressed. When the stall circumferential movement does not occur even when some of the stationary blades 72 stall, the level of noise and vibration hardly increases, so that the compressor can be operated at a lower flow rate.

[0035]

According to the present invention, a compression refrigerator capable of removing water or chlorine mixed in lubricating oil and enabling the use of a so-called alternative refrigerant is obtained.

According to the present invention, the centrifugal compressor can be operated up to a low flow rate region without generating a surge phenomenon and a rotating stall.

[Brief description of the drawings]

FIG. 1 is a system diagram of an embodiment of a turbo refrigerator of the present invention.

FIG. 2 is a detailed view of a water removing device used in the refrigerator of the embodiment of FIG.

FIG. 3 is a detailed view of another embodiment of the moisture removing device.

FIG. 4 is a system diagram of another embodiment of the turbo refrigerator of the present invention.

FIG. 5 is a longitudinal sectional view of a drive unit of the centrifugal compressor of the turbo refrigerator of FIG. 1;

FIG. 6 is a horizontal sectional view of an impeller of the centrifugal compressor of the turbo refrigerator of FIG. 1;

FIG. 7 is a longitudinal sectional view of a diffuser portion of the impeller of FIG. 6;

FIG. 8 is a layout diagram of stationary vanes and auxiliary wings of the impeller of FIG. 6;

[Explanation of symbols]

1 ... condenser, 2 ... evaporator, 3 ... compressor, 4 ... oil tank,
5 Drive source 6 Oil pump 7 Lubricating oil system 8 Moisture removal device (chlorine removal device) 9 Oil cooler 10 Oil strainer 11 Moisture detector 14, 32, 36 Refrigerant system 31 ... Ejector, 35 ...
Recovered oil system 60 ... motor casing, 60a, 68 ... bearing support frame 61 ... gear casing, 62 ... drive motor, 62a ... rotor, 62b ... stator 63 ... first shaft, 63a ... speed increasing gear, 64 ... Second shaft, 64a Pinion 64b Impeller, 65-1, 65-2, 66-1, 66
-2: bearing 67: oil supply hole, 71: impeller, 72: stationary blade, 73: stationary blade, 74: auxiliary wing 75: casing, 76: tongue

Claims (3)

(57) [Claims] An evaporator, a condenser, a centrifugal compressor for compressing refrigerant gas from the evaporator, a drive for driving the compressor, a lubricating oil system for circulating lubricating oil and a refrigerant system for circulating refrigerant. A first shaft directly connected to a rotor of a drive motor and having a speed increasing gear, and a second shaft having a pinion meshed with the speed increasing gear and having an impeller mounted thereon.
In the centrifugal compressor in which the first shaft and the bearings supporting the first shaft and the second shaft are housed in a casing, the first shaft directly connected to the rotor of the drive motor is increased. A second shaft bearing support frame having a pinion engaged with the first gear and the second shaft having a pinion engaged with the speed increasing gear; The centrifugal compressor is characterized in that a stationary blade is arranged in a diffuser, and a diffuser that converts the kinetic energy of the discharge fluid from the blade pressure into pressure energy by the stationary blade is provided in the centrifugal compressor. The leading edge is inclined in the downstream direction from the side plate side to the core plate side,
The auxiliary wing, which has a shorter chord length than the stationary wing and has a leading edge inclined in the downstream direction from the side plate side to the core plate side, the stationary wing so that one of the wing surfaces of the auxiliary wing faces the stationary wing. An oil recovery device that is arranged on the inner peripheral side of the wing, and on the other hand, is characterized in that a lubricating oil system is provided with a water removal device and a moisture detection unit, and an oil recovery device that collects lubricating oil mixed in the refrigerant into an oil tank. Provided in the refrigerant system, connected to the recovered oil system collected by the oil recovery unit to the ejector arranged in the lubricating oil system, return the recovered oil to the oil tank, and provided a water removal device in the lubricating oil system in which the ejector was arranged A turbo refrigerator. 2. The motor of claim 1, wherein the bearing of the first shaft is disposed between the speed increasing gear and the drive motor rotor, and the speed increasing gear and the rotor of the motor have an overhang structure. It is composed of a centrifugal compressor characterized by having
A turbo refrigerator comprising a refrigerant containing no Cl group, a synthetic oil as a lubricating oil, and a water removing device in a lubricating oil system. 3. The method according to claim 2, wherein the refrigerant is H
A turbo refrigerator using FC143a and an ester oil as a synthetic oil.