JPH03164531A - Emergency gas turbine - Google Patents

Abstract

PURPOSE:To reduce thrust force acting upon a ball bearing through an impeller by partitioning a space between the impeller of a compressor and a housing into two closed spaces, and communicating the respective closed spaces with atmospheric air respectively through separate communicating passages. CONSTITUTION:In an emergency gas turbine for generating rotating power by an output turbine receiving high-temperature high pressure combustion gas generated at a gas generator, a first labyrinth seal 30 is formed at a gap between the peripheral edge of the impeller 7 of the gas generator and a bearing housing part 19c. A second labyrinth seal 32 is also formed at a gap between an annular ring-formed protruding part 7c provided protrusively on the rear face 7b of the impeller 7, and the inner periphery of a protruding part 19e, provided protrusively on the bearing housing part 19c, facing the inner periphery of the annular ring-formed protruding part 7c with a minute gap. A space between the rear face 7b of the impeller 7 and the bearing housing 19c is thereby partitioned into a first and a second closed spaces 34, 35 which are communicated with atmospheric air respectively through a first and a second communicating passages 42, 36.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an emergency gas turbine.

(Prior art) In a gas turbine compressor, air is compressed by the rotation of an impeller, so the space between the surface of the impeller opposite to the air inlet side (hereinafter referred to as the "back surface") and the impeller housing. The pressure increases, and a thrust force acts to move the impeller toward the air inlet. This thrust force is received by a bearing that rotatably supports the end of the impeller on the air inlet side. For this reason, in the case of a gas turbine mounted on a boat, a ball bearing is not used as a bearing for receiving thrust force, but a bearing having a structure that can sufficiently withstand thrust force is used.

However, in the case of an emergency gas turbine, it is necessary to start up quickly when the bearings are not sufficiently supplied with lubricating oil, so ball bearings are used to receive the thrust force. If thrust force is applied, the life will be extremely shortened.

Therefore, in the case of conventional emergency gas turbines, an annular protrusion that protrudes in the axial direction is provided on the radially intermediate portion of the back surface of the impeller, and an annular protrusion that faces the impeller protrusion is provided on the housing. A labyrinth seal was formed in the gap between the protruding part of the impeller and the protruding part of the housing, and the space on the inner peripheral side of the labyrinth seal was communicated with the atmosphere through a pipe or the like.

(Problems to be Solved by the Invention) In the case of conventional emergency gas turbines, the area of the space communicating with the atmosphere among the spaces on the back side of the impeller is small, and the reduction of thrust force is insufficient. In other words, in order to increase the area of the space open to the atmosphere, it is necessary to form the protrusion to form a labyrinth seal as far outward in the radial direction as possible. However, since the impeller rotates at high speed, the protrusion should be If it is formed on the outside, a large stress will be applied to the impeller due to centrifugal force, which will cause problems other than thrust force. For this reason, the area of the space communicating with the atmosphere cannot be made sufficiently large.

This problem is particularly important in the case of two-shaft emergency gas turbines. That is, a turbine rotor for rotating the impeller is concentrically attached to the rear end of the impeller, and this turbine rotor applies a thrust force to the impeller in the opposite direction to the above thrust force. The thrust force was reduced. However, in the case of a two-shaft emergency gas turbine, the power turbine rotor that drives the output shaft is placed downstream of the turbine rotor.
The pressure of combustion gas downstream of the turbine rotor increases,
The thrust force reduction effect of the impeller by the turbine rotor is weakened. Therefore, in the case of a two-shaft type, the thrust force acting on the impeller is larger than in the case of a single-shaft type.

(Means for Solving the Problems) In order to solve the above problems, an emergency gas turbine according to the present invention includes an emergency gas turbine in which an end of an impeller of a compressor on the air inlet side is rotatably supported by a ball bearing. , a first labyrinth seal is formed in a gap between a housing covering a surface of the impeller opposite to the air inlet side and an outer peripheral edge of the impeller, and a first labyrinth seal is formed in a gap between a housing that covers a surface of the impeller opposite to the air inlet side, and a radius of the surface of the impeller opposite to the air inlet side is formed. An annular protrusion protruding in the axial direction is provided at a direction intermediate portion, an annular protrusion opposing the impeller protrusion is protruded from the housing, and the impeller protrusion and the housing A second labyrinth seal is formed in a gap with the protrusion, and the space between the impeller and the housing is transformed into a first closed space between the first labyrinth seal and the second labyrinth seal. and a second closed space on the inner periphery side of the second labyrinth seal, and a first communication passage that communicates the first closed space with the atmosphere, and the second closed space. A second communication path communicating with the atmosphere is provided.

(Function) Since the first closed space communicates with the atmosphere through the first communication path, and the second closed space communicates with the atmosphere through the second communication path, the pressure on the back side of the impeller is sufficiently smaller than the pressure of compressed air on the air outlet side of the impeller. Therefore, the thrust force acting on the ball bearing via the impeller is small.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4.

FIG. 2 is a schematic vertical sectional front view of an emergency gas turbine according to an embodiment of the present invention, and this embodiment employs a two-shaft emergency gas turbine. On the platform 1, which also serves as an oil pan for storing lubricating oil, there is a gas generator 2 that sucks in air and generates high-temperature, high-pressure combustion gas, and a generator that generates rotational power from the combustion gas generated by the gas generator 2. Output turbine 3 to be extracted
and a speed reducer 4 that reduces the rotational power extracted by the output turbine 3 to a predetermined rotational speed are arranged in this order from left to right. An auxiliary equipment gear box 5 is attached to the left side surface of the gas generator 2, which accommodates bearings, gears, etc. of various auxiliary equipment.

The gas generator 2 includes an impeller 7 that constitutes a rotor part of a centrifugal compressor 6 that compresses air, and creates high-temperature, high-pressure combustion gas by mixing and combusting compressed air and fuel. A combustor 8, a high-pressure turbine rotor 9 that is rotationally driven by combustion gas and rotates an impeller 7,
A low-pressure turbine rotor 10, etc., which is located downstream of the high-pressure turbine rotor 9 and operates in the same manner as the high-pressure turbine rotor 9, is provided. The output turbine 3 includes a power turbine rotor 12 located downstream of the low-pressure turbine rotor 10 and rotationally driven by combustion gas, and a power turbine rotor 1 .
2, an exhaust diff user 13 that decelerates the combustion gas, that is, exhaust gas after driving the engine 2, and an exhaust duct 14 that releases the exhaust gas, and a power turbine rotor 1.
The power turbine shaft 15 and the like rotate integrally with the power turbine shaft 2.

The reduction gear device 4 is configured to reduce the rotational power of the power turbine shaft 15 to a predetermined rotational speed and transmit it to the output shaft 17.
It includes an intermediate shaft 18, a plurality of gears, and the like.

The impeller 7 is covered by a housing 19, and the housing 19 includes a substantially cylindrical nose housing body 19a, a substantially cone-shaped bearing nose housing body 19b attached to one end of the housing body 19a, and a housing body. 1
A substantially cone-shaped bearing housing portion 19c is attached to the other end of the bearing housing portion 9a. One end of the impeller 7 is connected to a ball bearing 2 attached to the bearing housing part 19b.
The other end of the impeller 7 is rotatably supported around the axis by a roller bearing 21 attached to the bearing housing portion 19C. The outer periphery of one end of the impeller 7 is connected to the bearing housing portion 1
It faces the inner periphery of an annular seal member 22 attached to 9b with a slight gap therebetween, and the seal member 22 is located closer to the other end of the impeller 7 than the ball bearing 20 is. The outer layer of the other end of the impeller 7 faces the inner periphery of an annular seal member 23 attached to the bearing housing part 19C with a slight gap, and the seal member 23 is located at one end of the impeller 7 than the roller bearing 21. Located on the side.

A hole (
(not shown in the drawings).

A substantially cylindrical guide portion 19d that covers the blades 7a of the impeller 7 is integrally protruded from the housing body 19H, and the opening at the tip of the guide portion 19d forms an air inlet 24.

The air inlet 24 communicates with the atmosphere via a hole in the housing body 19a (not shown in the drawing) and an air intake pipe 25 connected to the housing body 19a. A passage 26 for supplying air compressed by the impeller 7 to the combustor 8 is formed between the housing body 19a and the bearing nozzle 1 housing portion 19c. The high pressure turbine rotor 9 and the low pressure turbine rotor 10 are connected to the impeller 7 by bolts 27.

FIG. 1 is an enlarged schematic longitudinal sectional front view of essential parts of an emergency gas turbine according to an embodiment of the present invention, in which a first labyrinth seal 30 is formed in the gap between the outer peripheral edge of the impeller 7 and the bearing housing part 19c. ing. As shown in detail in FIG. 3, the first labyrinth seal 30 is made up of a plurality of annular blades 31 (two in this embodiment) integrally protruding from the outer peripheral edge of the impeller 7. . Back side 7 of impeller 7
An annular protrusion 7C that protrudes toward the other end along the axial direction is integrally provided at the radially intermediate portion of the bearing housing portion 19c. A protrusion 19 faces the inner periphery of the protrusion 7C with a slight gap therebetween.
e is integrally provided in a protruding manner. A second labyrinth seal 32 is provided in the gap between the outer circumference of the protrusion 7c and the inner circumference of the protrusion 19e.
As shown in detail in FIG. 4, the second labyrinth seal 32 includes a plurality of annular blades (six in this embodiment) integrally protruding from the outer periphery of the protrusion 7C. 33. That is, the space between the back surface 7b of the impeller 7 and the bearing housing part 19c is the first closed space 34 between the first labyrinth seal 30 and the second labyrinth seal 32, and the space between the second labyrinth seal 32 and the first closed space 34 between the first labyrinth seal 30 and the second labyrinth seal 32. The second closed space 35 is also partitioned into a second closed space 35 on the inner peripheral side.
The closed space 35 communicates with the atmosphere through one or more (three in this embodiment) second communication passages 36 (not shown in FIG. 2). The communication path 36 of each node 2 connects the vibrator 37, the bearing housing portion 19c, and the housing body 19a.
It is composed of a hole 38 formed in the hole 38 and a pipe 39. Both ends of the vibrator 37 are fitted and fixed to pipe support members 40, 41 attached to the bearing housing part 19c.

The first closed space 34 communicates with the atmosphere via one or more (one in this embodiment) first communication passages 42 (not shown in FIG. 2). Although the passage 42 is not shown in detail in the drawing, it has the same configuration as the second communication passage 36, and is composed of a pipe 43 and the like.

Next, the operation will be explained. The rotation of the impeller 7 compresses the air sucked in from the air inlet 24 and supplies it to the combustor 8 through the passage 26 . This compressed air is mixed with fuel and combusted in the combustor 8 to become high-pressure combustion gas. This combustion gas rotates the high pressure turbine rotors 9, 10 and the power turbine rotor 12 at high speed, and then is exhausted through the exhaust duct 14. The impeller 7 rotates together with the rotation of the high pressure turbine rotors 9 and 10. The rotation of the power turbine rotor 12 causes the power turbine shaft 15 to rotate integrally, and its rotational force is reduced by the reducer 4 and output to the output shaft 1.
7.

At this time, the first. The first labyrinth seal is separated by a second labyrinth seal 30°32. The second closed space 34°35 is the first closed space.
Since it communicates with the atmosphere via the second communication path 42.36, the first. The pressure in the second closed space 34, 35 is sufficiently low compared to the pressure in the passage 26, and therefore the thrust force acting on the impeller 7 toward one end side of the impeller 7 is reduced favorably, and the thrust force causes a ball to be formed. A reduction in the life of the bearing 20 can be effectively prevented. Therefore, even in the case of a two-shaft emergency gas turbine in which the power turbine rotor 12 is arranged downstream of the low-pressure turbine rotor 10 as in this embodiment, the thrust acting on the impeller 7 toward one end side of the impeller 7 The force can be made sufficiently small, and therefore, without sacrificing the life of the ball bearing 20, the portion upstream of the power turbine rotor 12 of the emergency gas turbine including the compressor 6 can be divided into a single-shaft type and a two-shaft type. Can be used for both. Furthermore, since the first labyrinth seal 30 is provided to form the first closed space 34, there is no need to provide the protrusion 7C as far as possible on the radial outside of the impeller 7 in order to reduce the thrust force, and the impeller 7 is subjected to large stress. can be effectively prevented from acting. Further, since the space on the side opposite to the impeller 7 side of the bearing housing portion 19c is very narrow, there is a limit to the diameter of the pipe 37 that can be arranged, and one second communication path 36 is limited to the second closed space 35.
Although the pressure of 35 pressure can be lowered sufficiently.

(Another Embodiment) In the above embodiment, an example in which the present invention is applied to a two-shaft emergency gas turbine has been described, but it goes without saying that the present invention can also be applied to a single-shaft emergency gas turbine. be.

(Effects of the Invention) As explained above, according to the emergency gas turbine of the present invention, the first. A first labyrinth seal bounded by a second labyrinth seal. The second closed space is the first. Since it communicates with the atmosphere through the second communication path, the pressure in the first and second closed spaces is sufficiently low compared to the pressure of the compressed air compressed by the impeller, and therefore the impeller acting on the impeller The thrust force applied to one end of the ball bearing is effectively reduced, and reduction in the life of the ball bearing due to the thrust force can be effectively prevented. Therefore, even in the case of a two-shaft emergency gas turbine in which the power turbine rotor is placed downstream of the low-pressure turbine rotor, the thrust force acting on the impeller toward one end of the impeller can be sufficiently reduced, and the ball A portion upstream of a power turbine rotor in a two-shaft emergency gas turbine can be used for both a single-shaft type and a two-shaft type without sacrificing bearing life. In addition, since the first labyrinth seal is provided to form the first closed space, there is no need to provide the protrusion of the impeller as far outside the impeller in the radial direction as possible to reduce thrust force, and large stress is applied to the impeller. can be effectively prevented.

[Brief explanation of the drawing]

FIG. 1 is an enlarged schematic longitudinal sectional front view of the main parts of an emergency gas turbine according to an embodiment of the present invention, FIG. 2 is a schematic longitudinal sectional front view of the same emergency gas turbine, and FIG. Enlarged sectional view, FIG. 4 is an enlarged sectional view of the second labyrinth seal. 6... Compressor, 7... Impeller, 7C... Projection, one... Housing, 19e... Projection, 20.
...Ball bearing, 30...First labyrinth seal, 32
...Second labyrinth seal, 34...First closed space, 35...Second closed space, 36...Second communication path, 42...First communication path

Claims (1)

[Claims] 1. In an emergency gas turbine in which the air inlet side end of the impeller of the compressor is rotatably supported by a ball bearing, a housing that covers the surface of the impeller opposite to the air inlet side and an outer peripheral edge of the impeller. a first labyrinth seal is formed in the gap between the impeller and the housing; An annular protrusion facing the protrusion of the impeller is provided to protrude, and a second labyrinth seal is formed in the gap between the protrusion of the impeller and the protrusion of the housing, so that the impeller and the housing can be connected to each other. A space between the first labyrinth seal and the second labyrinth seal is divided into a first closed space between the first labyrinth seal and the second labyrinth seal, and a second closed space that is inner than the second labyrinth seal. , an emergency gas turbine comprising: a first communication path that communicates the first closed space with the atmosphere; and a second communication path that communicates the second closed space with the atmosphere.