WO2014087966A1

WO2014087966A1 - Centrifugal compressor, supercharger with same, and method for operating centrifugal compressor

Info

Publication number: WO2014087966A1
Application number: PCT/JP2013/082346
Authority: WO
Inventors: 浩一坂元; 白石　啓一
Original assignee: 三菱重工業株式会社
Priority date: 2012-12-05
Filing date: 2013-12-02
Publication date: 2014-06-12
Also published as: EP2930370A4; JP2014111905A; CN104903586A; EP2930370A1; KR20150081342A

Abstract

This centrifugal compressor is provided with an impeller (20) which rotates about an axis (L) and a labyrinth seal section (1) which seals between a wall section located on the rear surface side of the impeller (20) and the rear surface of the impeller (20). The labyrinth seal (1) has labyrinth grooves which are circumferential grooves centered on the axis (L). A cooling hole through which a cooling medium flows is connected to at least one of the labyrinth grooves.

Description

Centrifugal compressor, supercharger equipped with the same, and operating method of centrifugal compressor

The present invention relates to a centrifugal compressor and a turbocharger equipped with the same, and a method of operating the centrifugal compressor, and more specifically to cooling of the centrifugal compressor.

In the conventional centrifugal compressor, the temperature of the air at the outlet of the impeller is high according to the pressure ratio of the centrifugal compressor, and for example, even when air at normal temperature is sucked, the pressure ratio is about 4.5. The temperature of the air at the car exit reaches 200 ° C. or more. When this high temperature air passes through the labyrinth seal that seals between the outlet of the impeller and the space formed in the back of the impeller, the frictional heat generated by the relative rotation between the labyrinth seal and the fins of the impeller The air is further heated, and the high heat causes the back of the impeller to be heated. Generally, in a single-stage centrifugal compressor that absorbs such air, an aluminum alloy is used as a material of the impeller. However, since the strength of the material rapidly decreases as the temperature of the aluminum alloy rises from 220 ° C. to 250 ° C. or more, it has been difficult to design and operate at a high pressure ratio.
Therefore, Patent Document 1 discloses a technique of providing an air passage at an intermediate portion of the labyrinth seal portion and supplying cooling air to prevent the temperature rise of the impeller.
In addition, Patent Document 2 discloses a technique in which a cooling medium flows in from the outer peripheral side of the impeller.

Patent No. 2934530 Patent No. 4503726

However, even with the technology disclosed in Patent Document 1, the distance from the air passage of the intermediate portion to which the cooling air is supplied is longer than the impeller outer peripheral side where the impeller temperature is the highest. The cooling effect on the impeller outer peripheral side is low. Furthermore, an air passage separate from the labyrinth groove is provided in the middle of the labyrinth seal portion, and this air passage is widened in order to make the flow uniform in the circumferential direction. Therefore, the presence of the wide air passage reduces the number of labyrinth grooves, resulting in a reduction in sealing performance.
On the other hand, in the technology disclosed in Patent Document 2, the cooling effect is low because the cooling medium is not directly led to the impeller outer peripheral side where the impeller temperature is the highest.

The present invention has been made in view of such circumstances, and is provided with a centrifugal compressor capable of cooling an impeller and reducing metal temperature while securing the sealability of a labyrinth seal portion, and a centrifugal compressor including the same. It is an object of the present invention to provide a method of operating a supercharger and a centrifugal compressor.

In order to solve the above-mentioned subject, the centrifugal compressor of the present invention, the supercharger provided with this, and the operating method of a centrifugal compressor adopt the following means.
That is, in the centrifugal compressor according to the first aspect of the present invention, an impeller rotating around an axis, a labyrinth seal for sealing between a wall portion positioned on the back side of the impeller and the back of the impeller In the centrifugal compressor, the labyrinth seal section has a plurality of labyrinth grooves formed as a plurality of circumferential grooves centered on the axis, and at least one of the plurality of labyrinth grooves is cooled. There are connected cooling holes through which the medium flows.

According to the first aspect of the present invention, the cooling holes for supplying the cooling medium to the impeller are connected to the labyrinth grooves, which are circumferential grooves. As described above, by using the labyrinth grooves also as a space for supplying the cooling medium, it is possible to cool the impeller without reducing the number of labyrinth grooves. Thereby, coexistence of cooling of an impeller and the sealability by a labyrinth seal part can be aimed at.
Further, the metal temperature of the impeller can be lowered by providing a cooling hole in the labyrinth groove and supplying the cooling medium from the cooling hole to the impeller. This can prevent the temperature of the impeller from rising and the material strength from decreasing.

Furthermore, in the centrifugal compressor according to the second aspect of the present invention, an annular space through which the cooling medium flows is provided on the back side of the labyrinth seal portion, and the cooling hole includes the annular space and the labyrinth groove. To connect them, a plurality of each are formed in a separated state.

According to the second aspect of the present invention, since the annular space through which the cooling medium flows is provided, the cooling medium can be made uniform in the circumferential direction.
Further, since the annular space for uniforming the cooling medium in the circumferential direction is disposed on the back of the labyrinth seal portion and the cooling hole is provided to connect the annular space and the labyrinth groove, as in Patent Document 1, the labyrinth groove It is not necessary to provide an air passage that can not be used as a, and the labyrinth groove can be used directly for cooling. As a result, since it is not necessary to reduce the number of steps of the labyrinth groove, the sealing performance by the labyrinth seal portion can be secured.
Furthermore, by forming a plurality of cooling holes in a separated state, it is possible to effectively cool the impeller at various places in the circumferential direction.

Further, in the centrifugal compressor according to the third aspect of the present invention, the cooling hole is connected to the outermost labyrinth groove among the plurality of labyrinth grooves centered on the axis.

According to the third aspect of the present invention, by connecting the cooling hole to the outermost labyrinth groove, it is possible to feed the cooling medium directly to the portion where the metal temperature is the highest.

In the method of operating a centrifugal compressor according to a fourth aspect of the present invention, an impeller rotating step in which an impeller rotates around an axis by rotation of an exhaust turbine, and a labyrinth seal portion located on the back of the impeller And C. a cooling medium circulating step of circulating a cooling medium through at least one of the plurality of circumferentially arranged labyrinth grooves centered on the provided axis.

According to the fourth aspect of the present invention, since the cooling medium is caused to flow through at least one of the plurality of labyrinth grooves of the labyrinth seal portion, the impeller is cooled and metal is maintained while securing the sealability of the labyrinth seal portion. The centrifugal compressor can be operated with the temperature lowered. Thereby, the life extension of the impeller can be realized.

Furthermore, in the method of operating a centrifugal compressor according to the fifth aspect of the present invention, in the cooling medium circulating step, the cooling medium is supplied to the outermost labyrinth groove among the plurality of labyrinth grooves.

According to the fifth aspect of the present invention, by connecting the cooling hole to the outermost labyrinth groove, it is possible to feed the cooling medium directly to the portion where the metal temperature is the highest.

A turbocharger according to a sixth aspect of the present invention includes the centrifugal compressor according to any one of the above and an exhaust turbine that drives the centrifugal compressor.

According to the sixth aspect of the present invention, by providing the centrifugal compressor according to any one of the above, the impeller is cooled to lower the metal temperature while securing the sealability of the labyrinth seal portion. Can be a supercharger.

According to the present invention, the cooling hole for circulating the cooling medium is connected to at least one of the plurality of labyrinth grooves of the labyrinth seal portion, so that the impeller is cooled and metal is maintained while securing the sealing property of the labyrinth seal portion. The temperature can be reduced. Thereby, the life extension of the impeller can be realized.

It is a longitudinal cross-sectional view of the exhaust gas turbocharger provided with the labyrinth seal part concerning one embodiment of the present invention. The labyrinth seal part of FIG. 1 is shown, (a) is a longitudinal cross-sectional view of a labyrinth seal part, (b) is a top view of a labyrinth seal part. FIG. 3 is a side cross-sectional view showing a state in which a cooling hole is connected to a labyrinth groove located on the outermost side in the radial direction centering on the axis in the labyrinth seal portion shown in FIG. 2; It is a principal part longitudinal cross-sectional view which showed the circumference | surroundings of a labyrinth seal part shown in FIG. It is a graph showing the relationship between the cooling hole insertion position and the impeller metal temperature, where the horizontal axis is the cooling air insertion position and the vertical axis is the impeller metal temperature.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5.
FIG. 1 shows a longitudinal cross-sectional view of an exhaust turbine turbocharger (supercharger) 10 according to the present embodiment. The exhaust turbine turbocharger 10 is configured by integrally fastening the gas inlet casing 11, the gas outlet casing 12, the bearing stand 13, and the air guide casing 14 on the compressor side by bolts (not shown). The rotor shaft 15 is rotatably supported by the thrust bearing 16 and the

radial bearings

17 and 18 in the bearing base 13, and a turbine (exhaust gas turbine) 19 constituting a turbine unit is consolidated at one end, and the other end The impeller 20 which comprises a compressor part is consolidated.

The turbine 19 has a large number of blades 19 a at the outer peripheral portion. The blade 19 a is disposed between the exhaust gas introduction passage 22 provided in the gas inlet casing 11 and the exhaust gas discharge passage 23 provided in the gas outlet casing 12.
On the other hand, the impeller 20 is disposed at the rear of the intake air introduction passage 24 provided in the air guide casing 14. The intake air introduction passage 24 is connected to the swirl chamber 25 via an impeller 20, and the swirl chamber 25 is further connected to a combustion chamber of the engine via an intake air introduction passage (not shown).
Reference numeral 26 denotes a filter that rectifies the intake air by passing the intake air at a front stage sucked into the intake air introduction passage 24.

Further, a lubricating oil supply passage 27 is formed in the bearing stand 13, and a base end of the lubricating oil supply passage 27 is connected to an oil pump (not shown) of the engine. On the other hand, the other end of the lubricating oil supply passage 27 is branched into

branch passages

28, 29 and 30 connected to the thrust bearing 16 and the

radial bearings

17 and 18, respectively.

Furthermore, a labyrinth seal portion 1 is provided at the end of the bearing stand 13 on the impeller 20 side to seal between the wall portion located on the back side of the impeller 20 and the back surface of the impeller 20. The labyrinth seal portion 1 is in sliding contact with the impeller 20 to prevent leakage of compressed air.

At the time of operation of the exhaust turbine turbocharger 10 having such a configuration, for example, the exhaust gas from the marine diesel engine passes through the exhaust gas introduction passage 22 and is generated by the axial exhaust gas flow that is static pressure expanded by the turbine nozzle. The turbine 19 is rotationally driven. Then, the exhaust gas that has driven the turbine 19 is discharged from the exhaust gas discharge passage 23 to the outside.
The rotation of the turbine 19 rotates the impeller 20 through the turbine rotor shaft 15, and the air taken in through the inlet air introduction passage 24 is pressurized by the impeller 20 and passes through the diffuser 33 and the outlet scroll 35. And supplied to marine diesel engines.

Next, the configuration of the labyrinth seal portion 1 will be described in detail.
As FIG. 2 shows, the labyrinth seal part 1 is made into the ring shape which makes the axis line L a center axis line, for example, SS400 steel materials are used suitably.
The labyrinth seal portion 1 is fixed to the casing main body 37 (see FIG. 1) by inserting bolts into the plurality of outer periphery bolt holes 8a and the plurality of inner periphery bolt holes 8b provided substantially parallel to the axis L. (A state in which the labyrinth seal portion 1 is fixed by bolts is shown in FIG. 4). The outer peripheral bolt holes 8 a and the inner peripheral bolt holes 8 b are provided at substantially equal intervals all around the labyrinth seal portion 1.
As shown in an enlarged manner in FIG. 3, a plurality of stages of labyrinth grooves 3 are formed on one end face of the labyrinth seal portion 1, that is, the end face facing the impeller 20. The labyrinth groove 3 is a plurality of circumferential grooves centered on the axis L. Here, the groove dimensions (groove depth and groove width) of the respective labyrinth grooves 3 are approximately equal.

As shown in FIG. 4, an annular space 7 through which a cooling medium flows is formed on the back surface (right side in FIG. 4) of the labyrinth seal portion 1. The cooling medium supplied from the main engine is taken into the annular space 7 from the bearing stand 13 of the side of the turbocharger. The annular space 7 has an annular shape with the axis L as a central axis, and is formed so as to open toward the back of the labyrinth seal portion 1. Here, in FIG. 4, the annular space 7 has a substantially rectangular longitudinal cross section. Furthermore, the longitudinal dimension of the annular space 7, that is, the length in the direction orthogonal to the axis L (the longitudinal direction in FIG. 4) is long enough to cover a plurality of (four in the embodiment shown in FIG. 4) labyrinth grooves 3. It has become. The vertical dimension of the annular space 7 is appropriately set according to the required air amount.

The labyrinth seal portion 1 is provided with a cooling hole 5 formed from the end face on the opposite side to the end face on which the labyrinth groove 3 is formed (hereinafter referred to as "front face") (end face on the right in FIG. 4) It is done. The cooling hole 5 extends substantially in parallel with the axis L, and connects the outermost circumferential groove 3a and the annular space 7 facing the back surface. Here, the diameter of the cooling hole 5 is smaller than the diameter of the outermost peripheral groove 3a. In addition, as shown in FIG. 3, on the back side of the cooling hole 5, a taper processing for expanding the diameter toward the annular space 7 is applied, and the air flow from the annular space 7 becomes smooth. It is done.
As shown in FIG. 2B, the cooling holes 5 are provided at, for example, 24 places at substantially equal intervals all around the labyrinth seal portion 1.

FIG. 5 is a graph showing the relationship between the cooling hole insertion position and the impeller metal temperature, with the horizontal axis representing the cooling air insertion position and the vertical axis representing the impeller metal temperature (relative comparison). As shown in the figure, the metal temperature at the outermost periphery of the impeller is the highest, then the metal temperature at an intermediate position (in the impeller 20, the middle between the outermost periphery and the innermost periphery), and finally the center The order of the metal temperatures in the vicinity (near the rotor shaft 15 of the impeller 20) is the same.
Further, inserting the cooling air into the first stage (the cooling hole 5 connecting the outermost circumferential groove 3a and the annular space 7) is the highest in the cooling effect, and the second stage (the axial line L with respect to the outermost circumferential groove 3a) One cooling hole 5 located on the inner peripheral side, and finally the third step (cooling holes 5 located on the two inner peripheral sides of the outermost peripheral groove 3a with respect to the axis L).
Further, it can be seen that the cooling effect is remarkably high when the cooling air is inserted into the first stage cooling hole 5 as compared with the case where the cooling air is inserted into the second and third stage cooling holes 5. This is because when the cooling air is inserted from the second and third stages, the air entering the back of the impeller from the outer peripheral part of the impeller becomes hot due to friction, and the heat input is higher than when the cooling air is inserted from the first stage. It is to increase the number.

According to the configuration described above, according to the present embodiment, the following effects can be obtained.
Since the annular space 7 through which the cooling medium flows is provided on the back side of the labyrinth seal portion 1 and the cooling hole 5 is provided to connect the annular space 7 and the outermost peripheral groove 3a, seal air is circumferentially applied to the annular space 7 It is possible to make the flow uniform and thereafter supply the cooling air from the 24 cooling holes 5 of the labyrinth seal portion 1 to the outermost peripheral groove 3a. As a result, the number of the labyrinth grooves 3 need not be reduced, and the metal temperature of the impeller 20 raised to about 230 ° C. compared to the case where cooling is not performed while securing the sealability of the labyrinth seal portion 1 is approximately It can be lowered by 7 ° C.

In the above-described embodiment, it has been described that the cooling holes 5 are connected to the outermost peripheral groove 3 a in the plurality of labyrinth grooves 3. However, the present invention is not limited to this. For example, the cooling hole 5 may be connected to the labyrinth groove 3 located on the inner peripheral side of one of the outermost peripheral groove 3a.
Moreover, in each embodiment mentioned above, the number of the holes of the labyrinth seal part 1 demonstrated as 24 places. However, the present invention is not limited to this, and is determined in consideration of the cooling effect, and may be an even place such as 12 places or 36 places or an odd place such as 21 places.
Moreover, in each embodiment mentioned above, the raw material of the labyrinth seal part 1 was demonstrated as SS400. However, this invention is not limited to this, For example, steel materials, such as SS490 or SS540, may be used.
Further, it has been described that the cooling holes 5 are provided substantially parallel to the axis L. However, the present invention is not limited to this, as long as the cooling hole 5 just connects the labyrinth groove 3 and the annular space 7 and may be oblique with respect to the axis L, for example.
Moreover, in each embodiment mentioned above, we decided to use air as a cooling medium. However, the present invention is not limited to this, and for example, water vapor may be used.

1 Labyrinth seal portion 3 Labyrinth groove 3a Outermost peripheral groove (Labyrinth groove located at the outermost side in the radial direction centering on the axis)
Reference Signs List 5 cooling hole 7 annular space 8a outer peripheral bolt hole 8b inner peripheral bolt hole 10 exhaust turbine turbocharger 11 gas inlet casing 12 gas outlet casing 13 bearing base 14 compressor side air guide casing 15 rotor shaft 16

thrust bearing

17, 18 radial bearing 19 Turbine 19a Blade 20 Impeller 22 Exhaust gas introduction passage 23 Exhaust gas discharge passage 24 Intake air introduction passage 25 Swirl chamber 26 Filter 27 Lubricating

oil supply passage

28, 29, 30 Branch passage 31 Compressor housing 33 Diffuser 35 Exit scroll 37 Casing body L Axis

Claims

An impeller rotating about an axis,
A labyrinth seal that seals between a wall located on the back side of the impeller and the back of the impeller;
In a centrifugal compressor equipped with
The labyrinth seal portion has labyrinth grooves formed as a plurality of circumferential grooves centered on the axis,
A centrifugal compressor characterized in that a cooling hole for circulating a cooling medium is connected to at least one of the plurality of labyrinth grooves.
An annular space through which the cooling medium flows is provided on the back side of the labyrinth seal portion,
The centrifugal compressor according to claim 1, wherein a plurality of the cooling holes are formed in a state of being separated from each other so as to connect the annular space and the labyrinth groove.
The centrifugal compressor according to claim 1 or 2, wherein the cooling hole is connected to a labyrinth groove on the outermost side among a plurality of the labyrinth grooves centered on the axis.
A centrifugal compressor according to any one of claims 1 to 3,
An exhaust turbine for driving the centrifugal compressor;
A supercharger characterized by having.
An impeller rotation process in which an impeller rotates around an axis by rotation of an exhaust turbine;
A cooling medium circulating step of circulating a cooling medium through at least one of a plurality of circumferentially spaced labyrinth grooves centered on the axis line provided in a labyrinth seal portion located on the rear surface of the impeller;
A method of operating a centrifugal compressor comprising:
The method of operating a centrifugal compressor according to claim 5, wherein in the cooling medium circulating step, the cooling medium is supplied to a labyrinth groove on the outermost side among the plurality of labyrinth grooves.