JP2000018007A - Bleed control valve for steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form the width of a bleed control valve narrow, miniaturize a rotor, improve an efficiency of a steam turbine, and standardize a casing by forming a ring shaped groove on a partition plate having a steam nozzle and a steam passage, and inserting a grid-like valve having a ball between a valve seat and a valve element in the groove. SOLUTION: In a partition plate 4, its outer periphery is brought into contact with a casing 1, its inner circumference is sealed with a rotor, and a steam nozzle and a steam passage communicated with the steam nozzle are mounted. A bleed control valve 7 is arranged on the partition plate 4 so as to communicate with the steam passage 6 according to the steam nozzle. Namely, a valve seat 10 and a valve element 12 having grid-like steam passages (b), (a) are inserted into a ring groove 11 formed on a high pressure surface side of the partition plate 4 at a prescribed intervals. The valve element 12 keeps a clearance which is necessary for the valve seat 10 through the ball 13, and hold rotatably. Grid-like valves 10, 12, 13 are assembled with the partition plate 4 so as to constitute the bleed control valve 7. Accordingly, a bleed valve installing part is shortened to the utmost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bleed control valve for a steam turbine.

[0002]

2. Description of the Related Art A steam turbine is provided with an inlet steam chamber on the inlet side and an exhaust chamber on the outlet side, and is provided with a steam inlet valve and a steam outlet valve, respectively. In the art, a steam chamber is formed by providing a partition plate, and a bleed nozzle and a bleed control valve are provided to extract steam from the middle and use the steam for another purpose.

[0003] For example, a spherical extraction control valve is used as a high pressure extraction control valve, a spool type extraction control valve is used at medium pressure, and a lattice extraction control valve is used at low pressure. The conventional lattice-shaped bleed control valve has a valve seat and a valve body in surface contact and requires a large operating force due to friction of a sliding surface, and thus cannot be applied to a high differential pressure portion. In addition, there is also a disadvantage that uneven operation occurs due to wear of the friction surface and uneven frictional force.

On the other hand, in a steam turbine, it is important to keep the distance between bearings of a rotor as short as possible in order to secure turbine efficiency and operational safety. However, in the valve structure as described above, the mounting portion of the bleed control valve becomes longer in the axial direction of the rotor, thereby increasing the shaft diameter of the rotor, causing labyrinth leakage of steam, increasing pressure loss, and increasing efficiency. Was causing the decline. Accordingly, if the width of the bleed control valve can be reduced and the length of the mounting portion in the axial direction can be reduced, efficiency can be increased.

In this bleed control, the bleed pressure, the bleed amount, the mounting position of the bleed nozzle and the like are determined by the arrangement of the turbine and the specifications in use. Had become. That is, the conventional bleeding nozzle is cast and formed integrally with the casing. For this reason, the casing was not standardized and had to be manufactured individually, so a wooden mold had to be manufactured each time. Therefore, if the bleed nozzle is manufactured separately and installed by machining, the casing can be standardized,
The wooden form can also be saved.

[0006]

SUMMARY OF THE INVENTION The present invention aims at shortening the distance between the bearings of the rotor and reducing the diameter of the rotor by reducing the width of the bleeding control valve and suppressing the length of the mounting portion in the axial direction. It is an object of the present invention to obtain a steam turbine bleed control valve capable of standardizing a casing by manufacturing a bleed nozzle separately and mounting the bleed nozzle by machining while improving the efficiency and operation stability of the steam turbine.

[0007]

A bleed control valve for a steam turbine, wherein a lattice valve having a ball between a valve seat and a valve body is used, and the lattice valve is incorporated in a partition plate. . The lattice valve was disposed through the casing and was driven to rotate by a reciprocating connecting rod. Further, the bleeding nozzle was formed by drilling a hole in the casing upstream of the partition plate by machining, and attached by welding. Further, a steam port narrow in the axial direction of the rotor and wide and flat in the circumferential direction was formed in the extraction nozzle.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below. FIG. 1 is a partial side sectional view of a steam turbine incorporating a bleed control valve according to the present invention, and FIG.
FIG. 2 is a front sectional view taken along line A. In the figure, 1 is a casing, 2 is a rotor, and 3 is a blade fixed to the rotor 2. Reference numeral 4 denotes a partition plate whose outer periphery is in contact with the casing 1 and whose inner periphery is labyrinth-sealed by the rotor 2 to partition the internal pressure of the casing.

Reference numeral 5 denotes a steam nozzle provided on the partition plate 4, and reference numeral 6 denotes a steam passage communicating with the steam nozzle 5. The steam nozzle 5 is arranged over the entire circumference of the partition plate 4 when performing full-circulation injection, and is partially disposed when performing partial injection. The steam passage 6 is arranged corresponding to the steam nozzle 5.

Reference numeral 7 denotes a bleed control valve incorporated in the partition plate 4 so as to communicate with the steam passage 6. The bleed control valve 7 is arranged corresponding to the arrangement of the steam nozzle 5. Reference numeral 8 denotes a bleed nozzle that opens on the high-pressure side of the partition plate 4, and has a steam port 9 that is thin in the axial direction of the rotor 2 and that is wide and flat in the circumferential direction. The steam port 9 is formed by machining. It is set in the drilled hole, and its periphery is welded and attached. In the illustrated example, the steam port 9 is set by being inserted into a hole.

FIG. 3 is a partially enlarged view of FIG.
FIG. 4 is a front sectional view taken along line BB of FIG. 3. The configuration of the bleed control valve 7 will be described below with reference to FIGS. Reference numeral 10 denotes a valve seat having a lattice-shaped steam passage b at a predetermined interval, which is inserted into a ring-shaped groove 11 provided on a high-pressure side surface of the partition plate 4 and fixed by screws or the like.
Reference numeral 12 denotes a valve body having a lattice steam path a of the same shape at a predetermined interval as in the valve seat, and is inserted into the groove 11 similarly to the valve seat.

The valve body 12 maintains a required clearance (shown in FIG. 3) with the valve seat 10 via a ball 13 and is held rotatably. Reference numeral 14 denotes a metal support for the valve element 12 fixed to the partition plate 4 with screws or the like, which prevents the valve element 12 from falling off. Reference numeral 15 denotes a connecting hardware fixed to the valve body 12, 1
Reference numerals 6 and 17 denote connecting rods for connecting to a separately provided servo motor (not shown), which penetrate the casing 1 from the side and are disposed in the casing 1, and are reciprocated by the operation of the servo motor. You.

Reference numeral 18 denotes a universal joint for connecting the connecting rods 16 and 17, and 19 denotes a support frame for the connecting rod 17. The connecting rod 16 is connected to the connecting hardware 15. Therefore, the valve body 12 can be reciprocally rotated by the operating force from the servomotor. A bush is inserted into the support frame 19, and a contact surface between the bush and the connecting rod 17 has a labyrinth seal structure. In the figure, 2
Reference numeral 0 denotes a retainer applied between the balls 13 to prevent the balls 13 from being biased during operation.

The configuration of the present invention is as described above. Next, the operation thereof will be described. Now, in the state shown in FIG. 2, since the steam passage a of the valve body 12 and the steam passage b of the valve seat 10 are not communicated, steam does not flow. Therefore, when the servomotor is operated, the valve body 12 is rotated via the connecting rods 16 and 17 and the connecting hardware 15, so that the steam passage a of the valve body 12 and the steam passage b of the valve seat 10 communicate with each other. Then, the steam flows according to the area where the steam passage a communicates with the steam passage b.

Since the inside of the casing 1 is divided into a high pressure side and a low pressure side by the partition plate 4, the differential pressure acts on the valve body 12 by an amount corresponding to the degree of communication between the steam passage a and the steam passage b. Will do. However, the force that pushes the valve element 12 due to this differential pressure is received by the ball 13. Therefore, the rotation of the valve body 12 is caused by the rolling friction, so that the rotation can be performed with a small operating force.

The bleed nozzle is mounted upstream of the partition plate, and its mounting position is determined by the arrangement and use specifications of the turbine. In the present invention, a hole is drilled in the casing 1 by machining, and a bleed nozzle 8 having a vapor port 9 which is thin in the axial direction of the rotor 2 and which is flat and wide in the circumferential direction is inserted therein, set, and attached by welding. Also, since the lattice valve 7 is configured to be incorporated in the partition plate 4, the casing 1
The degree of freedom of the mounting position above is increased.

[0017]

According to the present invention, the bleed control valve of the steam turbine has a structure in which the grid-like valve is incorporated in the partition plate, so that the bleed valve mounting portion can be minimized, and the valve element has a ball support. As a result, the frictional force of the valve body can be minimized, and the lattice-shaped valve can respond to any extraction pressure, which shortens the distance between the bearings of the rotor and reduces the diameter of the rotor. As a result, the efficiency of the steam turbine and the stabilization of its operation have been enhanced by the reduction of the labyrinth leakage loss.

Further, since the bleeding nozzle is manufactured separately, a hole is drilled in the casing by machining, and the bleeding nozzle is set in the hole and attached by welding, so that it is not necessary to match the shape of the casing with the bleeding nozzle. Standardization of casing became possible. In addition, the wooden shape can be saved. Further, since the steam port of the bleeding nozzle has a flat shape, the distance between the bearings of the rotor is also reduced at the mounting portion of the bleeding nozzle.

[Brief description of the drawings]

FIG. 1 is a partial side sectional view of a steam turbine incorporating a bleed control valve of the present invention.

FIG. 2 is a front sectional view taken along the line AA of FIG. 1;

FIG. 3 is a partially enlarged view of FIG. 1;

FIG. 4 is a front sectional view taken along line BB of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 Rotor 3 Blade 4 Partition plate 5 Steam nozzle 6 Steam passage 7 Extraction control valve 8 Extraction nozzle 9 Steam port 10 Valve seat 11 Ring-shaped groove 12 Valve 13 Ball 14 Support metal 15 Connection hardware 16 and 17 Connection rod 18 Free Joint 19 Support frame 20 Retainer

Claims (4)

[Claims] A valve having a ring-shaped groove provided in a partition plate having a steam nozzle and a steam passage, a valve seat provided with a grid-shaped steam passage in the ring-shaped groove, and a valve body provided with a grid-shaped steam passage. And, insert a lattice valve having a ball between the valve seat and the valve body,
A bleeding control valve for a steam turbine, wherein a grid-like valve is incorporated in a partition plate by connecting a grid-like steam passage of a valve seat to the steam passage of the partition plate. 2. A casing is arranged so as to penetrate the casing from the side,
2. The bleed control valve for a steam turbine according to claim 1, wherein the lattice valve is rotated by a reciprocating connecting rod. 3. A bleed control valve for a steam turbine according to claim 1, wherein a hole is drilled in the casing by machining, and a bleed nozzle is set in the hole and attached by welding. 4. A bleed control valve for a steam turbine according to claim 3, wherein the bleed nozzle is provided with a steam port which is narrow in the axial direction of the rotor and wide and flat in the circumferential direction.