JPH08319806A - Thrust regulating device for bleeding turbine - Google Patents

Abstract

PURPOSE: To regulate thrust of a bleeding turbine without providing restricting in demand of air bleeding for a plant, and without increasing mechanical loss. CONSTITUTION: A device is constituted by a pressure sensor 12 for detecting pressure of air bleeding points 6a to 6e of respective step on a low pressure part, a switching valve 7 for selecting and switching an air bleeding point meeting thrust in the air bleeding points 6a to 6e, a second balance pipe 2b for connecting the switching valve 7 and the thrust bearing side of a second balance piston 3b to each other, a pressure sensitive sensor 9 for detecting pressure of a thrust metal 10, and a calculator 13 for being generated a signal to an actuator 8 for operating the switching valve 7 by calculating reverse flow direction pressure. The thrust applied on the thrust metal 10 is regulated to be a set value and less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thrust adjusting device for adjusting the thrust of a reaction type extraction turbine.

[0002]

2. Description of the Related Art In a reaction type turbine, about half of the pressure drop of steam is carried out by a moving blade, and the turbine is rotated by utilizing the reaction force of steam ejected from the moving blade. Produces thrust. This thrust increases almost in proportion to the flow rate of steam passing through the blade. A thrust bearing is provided to support this thrust, but since the thrust is usually much larger than the proof stress of the thrust bearing, a balance piston is used to reduce the thrust. FIG. 2 is a system diagram for explaining the function of the balance piston of the steam turbine. In Fig. 2, paragraph 1a on the axle 4
A paragraph group 1 composed of 1b is provided. Steam flows from left to right. The pressure in the passenger compartment 5a is P ₁ , the pressure in the passenger compartment 5b is P ₂ , and the pressure in the passenger compartment 5c is P ₃ . By connecting the thrust bearing side and passenger compartment 5b of the balance piston 3 by the balance tube 2, the thrust bearing side pressure P _2a of the balance piston 3 will be equal to P _2, since _{P 2 <P 1, P 2a} <
P ₁ , which causes a pressure difference on both sides of the balance piston 3, and thrust T _{1 in} paragraph 1a and thrust T ₁ in paragraph 1b.
Can be balanced with ₂ . Balance piston 3
Although it is a single casing, the high pressure section and the low pressure section operate like independent turbines. In the case of the extraction turbine, a two-stage balance piston is provided, and the front surface of the step portion of the balance piston and the pressure point in the middle paragraph are connected by balance pipes, respectively, so that the thrust can be reduced.

[0003]

In the case of a turbine without bleed air, a balance piston and a balance pipe can be used to balance the thrust acting on the rotor blades. This is because the thrust increases in proportion to the flow rate, but both the pressure on the passenger compartment side of the balance piston and the pressure on the counter flow direction side also increase in proportion to the turbine inlet flow rate. However, in the case of the extraction turbine, the pressure on the passenger compartment side is proportional to the turbine inlet flow rate, but in the wake paragraph, the pressure is affected by the extraction amount because it is extracted in the middle of the wake, and changes regardless of the turbine inlet flow rate. Therefore, even if the balance piston has two stages, the thrust acting on the moving blades of the low pressure part is reduced by the influence of the bleed air, and it becomes difficult to keep the difference between the thrust by the balance piston and the thrust acting on the moving blades small. .
Conventionally, the amount of bleed air in the plant has been limited, or the thrust bearing has been increased to increase the mechanical loss.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bleed turbine thrust adjuster for adjusting the thrust of a bleed turbine without limiting the bleed demand to the plant and without increasing mechanical loss. To do.

[0005]

In a bleed turbine for bleeding from a paragraph in the middle of a steam turbine, a pressure sensor for detecting the pressure at the bleed point of each paragraph of the low pressure section and each of the paragraphs coupled via a bleed pipe. A switching valve that selects and switches the bleeding point that matches the thrust from among the bleeding points, a balance pipe that is connected to the switching valve at one end and is connected to the thrust bearing side of the balance piston at the other end, and is provided at the turbine end. The pressure sensor for detecting the pressure of the thrust metal and the signal from the pressure sensor and the signal from the pressure sensor are input, and the thrust applied to the thrust metal is controlled so as to be equal to or less than a predetermined value. The above-mentioned object is achieved by comprising a computing unit that computes a flow direction pressure and issues a switching signal to an actuator that operates the switching valve.

[0006]

In the present invention, the pressure sensor for detecting the pressure at the extraction point of each paragraph of the low pressure section and the extraction point suitable for the thrust are selected from the extraction points of each paragraph connected through the extraction pipe. A switching valve for switching, a balance pipe having one end connected to the switching valve and the other end connected to the thrust bearing side of the balance piston, and a pressure sensor for detecting the pressure of thrust metal provided at the turbine end, Input the signal from the pressure sensor and the signal from the pressure sensor, calculate the pressure in the counter-flow direction so that the thrust applied to the thrust metal will be below the specified value, and send the switching signal to the actuator that operates the switching valve. It is composed of a computing unit that emits, and the counter pressure in the counter-flow direction is calculated by the computing unit so that the thrust is below a specified value. It is connected to the extraction point of closest paragraph pressure prompted Kawaben. In this manner, the thrust is adjusted by guiding the counter-direction pressure to the balance piston.

[0007]

1 is a system diagram of a thrust adjusting device for an extraction turbine according to an embodiment of the present invention. 1, the same parts as those in FIG. 2 are designated by the same reference numerals. In the example of FIG. 1, the balance piston is composed of a first balance piston 3a and a second balance piston 3b in two stages, and is bleed from the exhaust side vehicle compartment 5b of the high pressure part and supplied to the process, and the remaining steam is supplied to the low pressure part. Supplied. By the first balance pipe 2a, the exhaust side vehicle compartment 5b of the high pressure portion and the second balance piston vehicle compartment side 1
4b, and the thrust is independently balanced in the high pressure section. 1a is a paragraph of a high voltage part, 1b, 1c, 1d, 1
e and 1f are paragraphs of the low pressure part. Reference numerals 5a, 5b and 5c are passenger compartments, respectively. 6a, 6b, 6c, 6d and 6e are the extraction points of the paragraphs. In the present invention, the pressure sensor 8 for detecting the pressure of the extraction points 6a to 6e of each paragraph of the low pressure portion and the extraction air corresponding to the thrust from the extraction points 6a to 6e of each paragraph connected via the extraction pipe 11. A switching valve 7 for selecting and switching points, a second balance pipe 2b having one end connected to the switching valve 7 and the other end connected to the thrust bearing side of the second balance piston 3b, and a thrust provided at the turbine end. A pressure sensitive sensor 9 for detecting the pressure of the metal 10,
The signal from the pressure sensor 9 and the signal from the pressure sensor 12 are input, and the counterflow direction pressure is calculated and the switching valve 7 is operated so that the thrust applied to the thrust metal 10 is equal to or less than a predetermined value. The thrust adjusting device is composed of the calculator 13 that issues a switching signal to the actuator 8 that operates. The counter 13 calculates the pressure in the counter-flow direction so that the thrust becomes equal to or less than the predetermined value by the calculator 13, and connects the second balance pipe 3b to the pressure point of the paragraph closest to the calculated pressure. Thus, when the extraction flow rate is large and the steam to the turbine low pressure section is small and the thrust is small, and when the extraction flow rate is low and the steam to the turbine low pressure section is large and the thrust is large, the thrust is below the specified value. Since the bleeding point is calculated and the bleeding point is switched by the actuator, the thrust does not exceed the predetermined value. For this reason, the thrust bearing can be downsized, and it is not necessary to limit the operation demand on the plant side.

[0008]

According to the present invention, the pressure sensor for detecting the pressure at the extraction point of each paragraph of the low pressure portion and the extraction point suitable for the last among the extraction points of the paragraphs connected via the extraction pipe are selected. A switching valve that selects and switches, a balance pipe that has one end connected to the switching valve and the other end connected to the thrust bearing side of the balance piston, and a pressure sensor that detects the pressure of thrust metal provided at the turbine end. , The signal from the pressure sensor and the signal from the pressure sensor are input, and the pressure in the counter-flow direction is calculated so that the thrust applied to the thrust metal becomes equal to or less than the specified value and switched to the actuator that operates the switching valve. It is composed of a calculator that emits a signal, calculates the bleeding point so that the thrust will be below the specified value, and switches it with the actuator, so adjust the thrust below the specified value. To. Therefore, the thrust bearing can be miniaturized without restricting the operation demand on the plant side.

[Brief description of drawings]

FIG. 1 is a system diagram of a thrust adjusting device for an extraction turbine according to an embodiment of the present invention.

FIG. 2 is a system diagram illustrating a function of a balance piston of a steam turbine.

[Explanation of symbols]

 1 paragraph group 1a paragraph 1b paragraph 1c paragraph 1d paragraph 1e paragraph 2 balance pipe 2a first balance pipe 2b second balance pipe 3 balance piston 3a first ballast piston 3b second balance piston 4 axle 5a vehicle compartment 5b vehicle compartment 5c vehicle compartment 6a Bleed point 6b Bleed point 6c Bleed point 6d Bleed point 6e Bleed point 7 Switching valve 8 Actuator 9 Pressure sensitive sensor 10 Thrust metal 11 Bleed tube 12 Pressure sensor 13 Arithmetic unit

Claims (1)

[Claims] 1. In a bleed turbine for bleeding from a paragraph in the middle of a steam turbine, a pressure sensor for detecting the pressure at the bleed point of each paragraph of the low pressure section and a bleed point of each of the paragraphs connected via a bleed pipe are connected. A switching valve for selecting and switching the extraction point suitable for the thrust from the inside, a balance pipe having one end connected to the switching valve and the other end connected to the thrust bearing side of the balance piston, and a thrust metal provided at the turbine end. A pressure-sensitive sensor that detects the pressure of, and a signal from the pressure-sensitive sensor and a signal from the pressure sensor are input, and the pressure in the counter-flow direction is adjusted so that the thrust applied to the thrust metal becomes equal to or less than a predetermined value. A thrust adjusting device for an extraction turbine, comprising: a calculator that calculates and outputs a switching signal to an actuator that operates the switching valve.