JPH0431601A - Controller for rotor thrust of gas turbine - Google Patents

Abstract

PURPOSE:To prevent skiding damage in a thrust bearing and the like from occurring due to over- or less-thrust of a rotor shaft by providing a differential equalizing valve for introducing a compressor outlet air to a balance piston chamber while maintaining a constant voltage. CONSTITUTION:In a balance piston 7, the pressure receiving area, that is an annular area generated by a diametrical difference between labyrinth seals 11 on the outer and inner circumferential sides is set so that a product of the pressure in a balance piston chamber 12 at the time when it is equal to a compressor outlet air pressure, that is the pressure at the time when the compressor outlet air is led into the balance piston chamber 12 without working a leaf spring 9, and the pressure receiving area of the balance piston 7, may be equal to the thrust value of a gas generator shaft 1. Then the spring force is set so that a differential pressure which is equal to the pressure obtained by dividing the force almost equal to the lower limit thrust generating no skiding in a thrust bearing 3 by the above pressure receiving area may be generated. Then a differential pressure equalizing valve is constituted of the leaf spring 9 and a valve 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotor thrust control device for a gas turbine engine.

[Conventional technology]

In conventional gas turbine engines, in order to control the thrust of the rotor, it is common to introduce compressor outlet air into the balance piston chamber directly or through a certain restriction.

In engines using multistage compressors, intermediate stage compressor outlet air may be introduced directly into the balance piston chamber.

[Problem to be solved by the invention]

The conventional rotor thrust control device described above has the following problems to be solved.

In other words, in recent gas turbines, the DN value of the thrust bearing (
If the rotational speed (rpm x bearing inner diameter) exceeds 2 million and the rotor shaft thrust is too small, skinning
(slip phenomenon) and cause damage. On the other hand, under excessive thrust, it generates heat and shortens its life.

Therefore, it is important to control the rotor thrust to a substantially constant lower limit value that does not cause skidding of the bearing under all operating conditions.

Conventional devices have a problem in that the thrust of the rotor changes significantly with changes in engine speed, changes in the labyrinth seal gap used in the balance piston chamber, or changes in operating altitude. Further, in engines having variable stator vanes at the compressor inlet, there is a problem in that the rotor thrust changes significantly depending on the operation of the variable stator vanes.

[Failure to solve the problem]

The present invention provides a means for solving the above-mentioned problems, and is directed to a gas turbine having a balance piston chamber constructed of a labyrinth seal or the like between a rotating part and a stationary part for the purpose of adjusting the thrust of the shaft of a gas generator consisting of a pressure vM machine and a turbine. Provided is a rotor thrust control device for a gas turbine, characterized in that the device is equipped with a constant differential pressure valve that is installed to maintain a constant differential pressure and introduce compressor outlet air into a balance piston chamber. This is what I am trying to do.

[Effect]

Since the present invention is configured as described above, it has the following effects.

In other words, the thrust of the gas generator shaft is almost dependent on the compressor outlet pressure under various operating conditions, and since the thrust of the gas generator shaft does not change significantly depending on the engine operating conditions, a pressure equal to the compressor outlet pressure acts on the balance piston. When this happens, determine the effective pressure-receiving area of the balance piston so that the thrust of the gas generator shaft becomes almost zero.

Next, when the compressor outlet air is introduced into the balance piston chamber through a constant pressure differential valve that has a differential pressure equal to the pressure obtained by dividing the load equal to the lower limit thrust at which skinning does not occur in the thrust bearing by the effective pressure receiving area of the balance piston. , the load generated by the pressure difference is applied to the thrust bearing, and the thrust bearing does not skin.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a cross-sectional view of a rotor thrust control device for a centrifugal compressor type gas turbine according to this embodiment, showing only one side of a gas generator shaft 1.

In the figure, 1 is the gas generator shaft, 2 is the compressor, and 3
1 is a thrust bearing that is located between the end of the gas generator shaft 1 and the casing side and receives the thrust of the gas generator shaft 1; 4 is a combustor for generating gas; 12 is a balance piston chamber to be described later.

FIG. 2 is an enlarged view of the box (2) in FIG. 8 is a balance piston that uses the pressure of the compressor outlet air that has flowed into the balance piston chamber 12 to offset the excessive load on the thrust bearing 3 due to the thrust of the gas generator shaft l; 8 is the balance piston 7; A balance piston cylinder forming a cylinder, 9 a leaf spring for lowering the pressure of compressor outlet air flowing into the balance piston chamber 12 by a constant pressure as described later, 10 pushed by the leaf spring 9 into the balance piston chamber 12 A valve for suppressing the inflow of compressor outlet air, 11
balance piston cylinder 8 due to the labyrinth effect
A labyrinth seal 12 is used to press the balance piston 7 in the direction of the arrow marked "Thrust J" in the figure to offset the thrust of the gas generator shaft 1 by the required value. This is the balance piston chamber.

In the above configuration, the balance piston 7 introduces the compressor outlet air into the balance piston chamber 12 at the pressure when the pressure inside the balance piston chamber 12 is equal to the compressor outlet air pressure, that is, without applying the leaf spring 9. The pressure receiving area, the diameter between the labyrinth seals 11 on the outer circumferential side and the inner circumferential side in the figure, is adjusted so that the force obtained by multiplying the pressure by the pressure receiving area of the balance piston 7 and the thrust of the gas generator shaft 1 are approximately equal. The annular area created by the difference is set. The puffing force of the plate spring 9 is not set so as to generate a pressure difference equal to the pressure obtained by dividing a force approximately equal to the lower limit thrust at which the thrust bearing 3 does not cause skinning by the pressure receiving area. That is, the leaf spring 9 and the pulp 10 constitute a constant differential pressure valve.

Since this embodiment is configured as described above, even when the compressor outlet air pressure or other fluctuations occur, the load on the thrust bearing 3 does not decrease below the lower limit value that does not cause skidding of the thrust bearing 3. This has the advantage of preventing damage to the

Furthermore, since the thrust bearing 3 is not loaded with a thrust that is larger than the thrust generated by the constant differential pressure, there is an advantage that reduction in the life of the thrust bearing 3 can be prevented.

Further, since the amount of air supplied to the balance piston chamber 12 can be suppressed to the necessary minimum by the leaf spring 9 and the valve 10, there is also the advantage that the fuel efficiency of the engine is improved.

In addition, since the lower limit value of the thrust for the thrust bearing 3 is guaranteed and excessive values are eliminated, the advantage is that the operable range of the variable inlet stator vane of the compressor 2, which is related to the acceleration/deceleration performance of the engine, can be expanded. There is.

〔Effect of the invention〕

Since the present invention is configured as described above, it has the following effects.

(1) Squeezing damage to the thrust bearing due to insufficient thrust of the rotor shaft (which usually leads to fatal damage to the engine) can be prevented.

(2) It is possible to prevent reduction in the life of the thrust bearing due to excessive thrust of the rotor shaft.

(3) Since the amount of air supplied to the balance piston can be kept to the minimum necessary by using differential pressure and drilling, it can also contribute to improving the fuel efficiency of the engine.

(4) Due to the effect of (1), it is possible to expand the operable range of the compressor inlet variable stator vane related to engine acceleration/deceleration performance.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a rotor thrust control device for a gas turbine according to an embodiment of the present invention, and FIG. 2 is a diagram showing enclosure H in FIG. 1.
It is an enlarged view of. 1...Gas generator shaft. 2... Compressor, 3... Thrust bearing. 4...Combustor, 7...Balance piston. 8...Balance piston cylinder. 9...Plate plate 10...Valve 12...Balance piston chamber.

Claims (1)

[Claims] In a rotor thrust control system for a gas turbine, which has a balance piston chamber configured with a labyrinth seal between the rotating part and the stationary part for the purpose of adjusting the thrust of the gas generator shaft, which consists of a compressor and a turbine, a constant differential pressure is maintained. 1. A rotor thrust control device for a gas turbine, comprising a constant differential pressure valve configured to introduce compressor outlet air into a balance piston chamber.