JPS5857601B2 - low boiling point media turbine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbine that uses a low-boiling point medium as a working fluid, and more particularly to a low-boiling point medium turbine that can reduce thrust generated before and after a rotor.

In general, in turbines that use a low boiling point medium as the working fluid in power generation equipment that utilizes medium-low temperature difference, in order to obtain a high heat drop, the pressure ratio between the inlet and outlet of the turbine must be large. The directional thrust also becomes extremely large depending on the output.

Therefore, effectively reducing this thrust is
The problem is even greater in low-boiling medium turbines than in regular steam or gas turbines.

Furthermore, the low boiling point medium used in this turbine is not only expensive but also toxic and explosive, and is often dangerous if it leaks outside the machine, so it is sealed and circulated using a shaft seal device. There is a need to.

Therefore, turbines that use a low boiling point medium as the working fluid have a special structure equipped with a shaft sealing device.
The development of a method that can efficiently reduce thrust using a simple device has become an important issue.

Conventionally, methods employed to reduce thrust in steam or gas turbines include the following.

In other words, first, the turbine stage is divided into two major parts,
The second method is the double flow method, in which the thrust directions are opposed on the same axis and the respective thrusts cancel each other out.The second method is the balance hole method, in which the nozzle is diaphragm-shaped and a balance hole is provided in the rotor disk.The third method is the low pressure on the rotor end surface. High-pressure steam or gas is guided to the low-pressure stage outlet and a labyrinth seal is used to maintain the pressure difference and reduce the overall ρ thrust, or a hole is provided in the disc rotor to connect the high-pressure side rotor end face with the low-pressure exhaust chamber using a balance piston. This includes methods, etc.

The first method can completely solve the problem of thrust, but has the disadvantage of increasing the overall structure.The second method cannot be expected to significantly reduce thrust, but rather improves turbine performance. This is an attempt to improve the results.

The third method is more effective than the second method, but is still not sufficient to reduce thrust.

In addition, all of the above-mentioned methods have complicated structures and have problems in terms of materials and costs.

Furthermore, even if these methods are applied to low-boiling point medium turbines, it is necessary to consider the increase in the shaft diameter and the pressure-receiving area of the thrust bearing in response to the increase in thrust, similar to conventional small and medium-sized steam turbines. A new problem arises.

For example, a conventional device employing the third method, which has a relatively simple structure and is effective in reducing thrust among the above-mentioned methods, will be described with reference to FIG.

Fig. 1 shows the configuration of a conventional waste gas turbine using a balance piston. In the figure, reference numeral 1 indicates the turbine main shaft. This main shaft 1 is supported at both ends by bearings 2. A rotor 3 and a piston 4 are provided between them.

On the surface of this rotor 3, there are a plurality of rotor blades 5, 5.
.

. . . 5 is fixed, while the rotor blades 5, 5 .・
・・・・・・A conical casing 6 between each of 5
A plurality of stationary blades 7, 7.・・・・・・7
are arranged alternately to form a turbine casing 8.

In addition, the gas is supplied to the turbine through the main stop valve 9.
The air enters the turbine casing 8 from 0, rotates the rotor 3, and is exhausted from the turbine outlet 11.

At this time, the thrust by the main stream of gas is the high pressure end face 1 of the rotor 3.
2 and rotor blades 5 to the right - in response to this thrust, the high pressure sealed air sent from the compressor 13 enters the balance piston section 14 and acts on the high pressure piston face 15 to the left in the figure, reducing the overall thrust.

This high-pressure air then passes through the labyrinth packing 16 and flows out of the machine, or enters the turbine casing 8 to also cool the rotor 3.

The conventional turbine configured in this manner requires a compressor to supply gas for the balance piston, and has the disadvantage that the shape of the rotor shaft is complicated.

Furthermore, when this was made into a shaft-sealed type, there was a problem in that it was impossible for the gas for the balance piston to leak out of the machine, making it impossible to obtain a pressure difference before and after the labyrinth seal.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a low-boiling point medium turbine that eliminates the above-mentioned drawbacks of conventional devices and can reduce thrust extremely effectively without making the overall structure complicated or large. There is a particular thing.

In order to achieve the above object, the present invention provides a turbine using a low boiling point medium as a working fluid, in which balance piston chambers are provided on the upstream side and downstream side of the rotor, and the balance piston chamber on the upstream side of the rotor and the turbine outlet exhaust gas are provided. A low-pressure piping is connected between the chamber and the balance piston chamber to communicate between the two, while a high-pressure piping is connected between the turbine inlet side and the balance piston chamber on the downstream side of the rotor, and a part of the high-pressure working fluid is transferred to the downstream side of the rotor. It is characterized by having a branch introduced into the balance piston chamber.

Embodiments of the low boiling point medium turbine according to the present invention will be described below with reference to FIGS. 2 and 3.

In FIG. 2, reference numeral 17 indicates a turbine main shaft, and this main shaft 17 is supported at both ends by bearings 18, 18, with a central rotor 19 sandwiched between the bearings 18, 18, and a piston 21 on the upstream side. A piston 22 is provided on the downstream side.

On the surface of this rotor 19, there are a plurality of rotor blades 23 , 23 ,
. . . 23 is fixed, while a frusto-conical casing 2 whose apex is on the piston 21 side covers the rotor 19 and the rotor blades 23 , 23 , . . . 23 .
4 are provided, and a plurality of stationary blades 25, 25 . . . 25 are arranged alternately adjacent to rotor blades 23, 23, . . . 23 to form a turbine casing 26.

Then, the working fluid enters the turbine casing 26 from the turbine inlet 28 through the turbine main stop valve 27, converts the stored energy into mechanical work and rotates the rotor 19, and in the process, the pressure drops and becomes low-pressure fluid. and is sent out from the turbine outlet 29.

Further, on the inlet side of the turbine casing 26, a rotor end surface 19 is provided.
A balance piston chamber 30 is provided to enclose the piston 21 in contact with a, and the outside of this balance piston chamber 30 is sealed by a shaft sealing device 31 to prevent leakage of working fluid to the outside of the machine.

Inside the balance piston chamber 30, a labyrinth packing 32 is provided between the inner wall of the piston chamber and the circumferential surface of the piston 21, and a balance piston portion is provided between the inner wall of the piston chamber and the end surface 21a of the piston 21. 33 is formed.

Furthermore, the lower part of the balance piston section 33 and the turbine outlet 29 are connected by a low pressure pipe 34, and the two are communicated with each other.

Similarly, a rotor end face 19 is provided on the outlet side of the turbine casing 26.
A balance piston chamber 35 is provided to contain the piston 22 in contact with the balance piston chamber 35.
The outside of the shaft is sealed by a shaft sealing device 36.

Further, inside the balance piston chamber 35, a labyrinth packing 3T is provided between the outer periphery of the piston 22 and the balance piston chamber wall, and a balance piston portion is provided between the end surface 22a of the piston 22 and the balance piston chamber wall. 38 is formed.

Furthermore, the balance piston section 38 here - bottle inlet 2
8 is connected by a high-pressure pipe 39, a part of the high-pressure working fluid flowing from the turbine main stop valve 27 toward the turbine inlet 28 can be bypassed and introduced into the balance piston portion 38.

Since the present invention is configured in this way, the working fluid entering the turbine casing 26 from the turbine inlet 28 flows through the high pressure side rotor end face 19a that is in contact with the upstream side balance piston chamber 30.
A rightward thrust is applied to this end face 19a.
Since the high pressure receiving area of is formed to be small lengthwise,
The rightward pressure acting on this surface is not very large.

In addition, the working fluid is connected to the piston 21 and the labyrinth packing 3.
2, the pressure decreases and the balance piston part 3
Leading to 3.

The balance piston part 33 connects the outlet exhaust chamber 29 and the low pressure pipe 3
4, so the balance piston part 33
This reduces the rightward thrust acting on the balance piston end face 21a.

In the downstream balance piston chamber, the high pressure fluid at the turbine inlet is transferred to the balance piston section 3 through the high pressure piping 39.
8, the pressure of this high-pressure fluid acts leftward on the balance piston end surface 22a.

Then, this working fluid passes through the labyrinth packing 37 and its pressure drops to the low exhaust pressure, and the turbine outlet 29
leak to.

Due to the action of the balance piston part, the thrust acting in the right direction in FIG.
The end backing thrust that acts on the blade a and the net blade thrust that acts on the effective part of the blade.On the contrary, the thrust that acts leftward is the thrust that acts on the end faces 22a and 19b.

These thrust forces are determined by the area of each end face, the pressure of each balance piston portion, that is, the diameter of the labyrinth packing, and the amount of pressure loss in the labyrinth and the communication pipe.

FIG. 3 shows another embodiment of the present invention. Even when a very small amount of seal oil is expected to leak from the shaft seal device, the present invention can be applied to prevent seal oil, etc. from entering the turbine casing. This is to prevent contamination.

The present embodiment will be described below with reference to FIG. 3, in which the same parts as in FIG. 2 are denoted by the same reference numerals.

First, if oil leaks from the shaft sealing device 31 on the upstream side to the inside of the machine, the flow of working fluid from the labyrinth seal 32 to the balance piston portion 33 prevents the oil from leaking into the turbine casing 26. Ru.

Even when oil leaks from the shaft sealing device 36 on the downstream side to the inside of the machine, the high-pressure working fluid introduced into the balance piston section 38 flows between the labyrinth packing 37 side and the shaft sealing device 3.
Since the flow is divided to both sides of 7, oil will not infiltrate into the turbine casing 26 against this flow.

In addition, in the case of leakage of seal oil from either the upstream or downstream shaft sealing device, the working fluid containing oil is guided to the low pressure side by the low pressure pipe 34 and the connecting pipe 40, and the oil separator 41 The oil is separated and joins the main stream at the turbine outlet.

Further, the oil accumulated in the lower portions of the balance piston parts 33 and 38 and the piston buffer chamber 42 is led to the seal oil tank 43.

As is clear from the above description, according to the present invention, a part of the working fluid of the turbine is used as gas for the balance piston, and balance piston chambers are provided on the upstream side and the downstream side of the rotor, respectively. Since the pressure difference between the end face of the high-pressure part and the end face of the low-pressure part of the piston is made to be almost equal to the pressure difference between the turbine inlet and outlet, it is possible to significantly reduce the amount of slug inflow with a simple device without making the turbine structure complicated or large. Mitigation can be done.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the configuration of a gas turbine using a conventional balance piston, Fig. 2 is a longitudinal sectional view showing an embodiment of a low boiling point medium turbine capable of reducing thrust according to the present invention, and Fig. 3 is a shaft FIG. 7 is a longitudinal cross-sectional view showing another embodiment of the present invention in which seal oil leaking from the sealing device can be prevented from entering the turbine casing. 3.19...0-1.4.21.22...
...Balance piston, 8,26...Turbine casing, 10°28...Turbine inlet, 11,2
9...Turbine outlet, 12.19a...
・High pressure side rotor end face, 15° 22a... High pressure balance piston surface, 16, 32° 37... Labyrinth packing, ・19b... Low pressure side rotor end surface, 21a... ...Low pressure ballast piston surface, 30.
...Upstream side balance piston chamber, 31, 36...
...Shaft sealing device, 34...Low pressure piping, 35.
・・・・・・Ship side balance piston chamber, 39...
・High pressure piping, 40...Connecting pipe, 41...
・Oil separator.

Claims (1)

[Claims] 1 In a turbine that uses a low-boiling point medium as the working fluid, balance piston chambers are provided on the upstream and downstream sides of the rotor, and the rotor upstream balance piston chamber and the turbine outlet exhaust chamber are connected by low-pressure piping. At the same time, high-pressure piping is used to connect the turbine inlet side and the balance piston chamber on the downstream side of the rotor, and a portion of the high-pressure working fluid is branched into the balance piston chamber on the downstream side of the rotor. A low boiling point medium turbine characterized by: