JPS5857572A - Main steam stop valve equipped with by-pass valves - Google Patents

Abstract

PURPOSE:To damp the velocity energy of steam and consequently prevent the steam passage from being corroded by a method wherein a by-pass valve is placed within a room, the entrance of which is throttled for lowering the pressure just before the by-pass valve. CONSTITUTION:A collar 12 is provided in the arm 21a of a disc so constructed as to throttle the inlet ''q'' of steam. The arm 21a is installed from the outer periphery of a main valve 16 so as to provide collars 15a and 16a having vertically shiftable notches 18a and 18b. Furthermore, each side wall surface 32 of the steam passage 35 is curved so as to form a semi-circular round surface in order to connect to the side wall surface 33 of the collars 15a and 15b with a circular arc 19, resulting in constituting a throttled chamber at the entrance of steam. The steam throttled at the steam inlet ''q'' expands itself abruptly at the chamber of the steam passage 35 and consequently the velocity energy preserved in the steam is damped and, after that, the steam is flowed through the slightly open opening of the by-pass valve 37 into a steam passing hole 22, resulting in preventing the projection 37a of the by-pass valve 37 and the steam passing hole 22 from being corroded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam stopper with a bypass valve for a steam turbine;
In particular, the present invention relates to a structure that prevents erosion in a bypass flow path.

The main steam stop valve targeted by the present invention does not allow steam to flow to the steam turbine when an emergency situation occurs in the steam turbine.
Installed for bypass via bypass valve.

As this main steam stop valve, a steam stop valve with a bypass valve is used, in which a bypass valve is provided in the main valve. The bypass valve is provided to allow a small amount of steam to flow through the turbine in order to relieve thermal stress generated in the turbine when the turbine is started.

An example of this steam stop valve with bypass valve is shown in Figures 1, 2 and 3.

First, the structure will be explained. A fan-shaped steam population 35 is formed on the upper surface of the main valve 16 and the lower surface of the valve cap 14,
A notch 34 is provided in the part of the valve cap 14 located above the steam port 35 from below in an upward and downward direction, and a length hole 27 is provided in the vertical direction in the center of the valve cap 14.
7 into the upper full round hole 27 of the disk 21 screwed into the upper end,
Bypass valve mounting arm 21a'f fitted so as to be movable downward and formed radially on the disk 21: Bypass valve mounting arm 21a'f fitted so as to be movable upwardly in the notch 34;
A hole 36 is drilled in the axial direction, and a bypass valve 37 is inserted into this hole 36.
The bypass valve 37 is attached by fitting the bottle 23 into the hole 38 that extends through the bypass valve 37 in the radial direction.

'1. In addition, a protrusion 37a is provided at the tip of the bypass cell 37 to guide the steam flow. With the disk 21 and bypass valve 37 installed, open the valve cap 1 from above.
4, and tighten with port 31 to make it one piece.

Next, the movement of the valve and the flow of steam will be explained.

When the turbine is started, the valve stem 17 is moved by a drive mechanism (not shown).
is pushed up, the tip surface of the valve stem 17 contacts the disk 21, and the disk 21 moves upward.

When the valve stem 17 is pushed up further, the valve 1 integrated with the disk 21 is removed.
The upper surface of the lIlii 21a contacts the head and shoulder of the bypass valve 37, and finally the bypass valve 37 opens slightly, allowing steam a to flow down and the turbine to start up, opening the bypass valve 37 as necessary.
The rotation speed (load) of the turbine is controlled by adjusting the opening degree of the turbine.

During this operation, parts of the steam passage may be eroded by solid particles contained in the steam. This is the steam passage 35
has a fan shape, and the side wall surface 35a has a straight line f, and the original part of the fan shape, that is, the center side (valve stem 17 side)
Since the flow path area of the steam a decreases, the steam is accelerated.Moreover, since the peripheral area of the steam passage hole 22 of the main valve 16 is in the same direction as the steam inflow direction, in the process of the steam a flowing in, the bypass valve 37, that is, only from one side of the half circumference in the steam inflow direction. Among them, most of the steam flows in from the x and x' directions, and steam X flows in from both sides.

X′ collides with each other at the back side °°J” part, and the flow n becomes turbulent and flows down to the steam passage hole 22. Therefore, the steam flowing from around the bypass valve 17 is no longer uniform, and the steam flows into the bypass valve tip 37.
The area around a has a different erosion situation.

Furthermore, erosion will be explained with reference to FIG. Steam a passes through the steam passage 35 and flows down from the slightly opened gap between the seat portions of the bypass valve 17 and the main valve 16 while accelerating. In this case, the direction of the steam is changed by the protrusion at the tip 37a of the bypass valve 37 and passes through the steam passage hole 22. At this time, the wall surface of the protrusion 37a is eroded by the solid particles contained in the steam. Furthermore, as shown by the dotted line IItI+, the solid particles may collide with the inner wall surface of the steam passage hole 22, thereby causing erosion of the "m" portion.

Further, the steam flows parallel to the valve stem 17 and collides with the head umbrella-shaped surface 24a of the belt housing 24 whose purpose is to guide the valve stem 17.
On '1 part may be eroded.

An object of the present invention is to prevent erosion of the steam passage portion of a main steam stop valve with a bypass valve, and to improve the reliability of a turbine.

Since steam flows at the speed of sound when the bypass valve is slightly open, it is conceivable that solid particles contained in the steam also flow in at the same speed.

Therefore, it is necessary to slow down the speed after passing through the bypass valve, and for this purpose it is conceivable to lower the pressure immediately before the bypass valve. In the present invention, the bypass valve is made into one chamber, and by narrowing the inlet of this chamber, the steam is rapidly expanded and the pressure immediately before the bypass valve is lowered.

The configuration and operation of an embodiment of the present invention will be explained below.

FIG. 5 shows the structure of the steam passage section of the present invention. The bypass valve 37 is assembled into the arm 21a of the disk 21 with the pin 23 as in the conventional method, but in the present invention, a collar 12 is provided on the arm 21a of the disk at the steam inlet portion to narrow the steam inlet "q". . On the other hand, as shown in FIGS. 6 and 7, the main valve 16
The arm 21a enters from the outer periphery of the notch and can be moved up and down!
! 18a.

18b'i - The collars 15a and 15b are provided.

Further, the side wall surface 32 of the steam passage 35 is given a curvature and formed into a semicircular R surface, and the connection with the side wall surface 33 of the brim 15a, 15b is formed by a circular vein 19. In other words, the steam passage 35
The steam inlet is shaped like a ginkgo leaf and forms a narrow chamber. In addition, the passage area of steam inlet 1 (qI+) is the same as that of bypass valve 3.
The area of the opening should be slightly larger than that of No. 7.

Next, the steam flow f will be explained.

When the valve $17 is pushed up, the disk 21 is raised, the bypass valve 37 is slightly opened, and the steam a flows in.

In this case, the steam passes through the entire passage of the two-stage throttle. In other words, the steam a, which has been throttled by the steam population ""qII, rapidly expands in the chamber of the steam passage 35, so the velocity energy of the steam is attenuated, and the steam a is drawn from the slightly open opening of the bypass valve 37 to the steam passage hole 22. and the protrusion 37a of the bypass valve 37
And erosion of the steam passage hole 22 is prevented. Also, as shown in FIG. 7, among the streams n of steam a, x-
The steam x' flows into the steam passage hole 22 along the side wall surfaces 33 of the brim 15a, 15b, the radius of curvature surface of the side wall surface 32 of the steam passage 35, and the smooth surface of the circular vein 19. Therefore, the air flows evenly from the entire circumference of the bypass valve 37, and there is no adverse effect on the bypass valve 37.

In addition, in order to avoid the steam that has passed through the bypass valve 37 from colliding with the downstream shingle housing 24, the downstream side of the steam passage hole 22a is connected to the outside of the main valve 16 (valve stem) from directly below the spherical seat of the bypass 9P37. 17) to change the direction of the flowing steam to the direction a'. [7] The outlet side of this hole is larger than the diameter directly below the spherical seat of the bypass valve 37 ('
I<'2), the steam flows down while expanding, so erosion of downstream parts can be prevented.

According to the present invention, the kinetic energy of the steam flow and solid particles can be attenuated, thereby preventing erosion of the steam passage section. In addition, erosion can be prevented by avoiding collision of the steam flow toward the downstream side.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional main steam stop valve with a built-in bypass valve, and Figures 2 and 3 are sectional views taken along the T-Tr arrow and ■-■ in Figure 2. , FIG. 4 is a partial cross-sectional view of a main steam stop valve showing locations where erosion is expected in a conventional type, and FIG. 5 is a partial cross-sectional view of a main steam stop valve according to an embodiment of the present invention.
FIG. 6 is a sectional view taken along the line ■--■ in FIG. 5, and FIG. 7 is a partially detailed view of FIG. 12...Brim, 15...Brim, 16...Main valve, 1
7... Valve stem - 118a, 18b... Notch, 19
...Arc, 21...Disk, 21a...Arm, 2
2... Steam passage hole, 23... Pin, 24... Throttle case, 30... Bypass valve, 32.33... Side wall surface,
35... Steam passage, 37... Bar 1 (¥1 Figure 4 Figure 5 Port 86 Figure 11

Claims (1)

[Claims] 1. The main valve (16) and this main valve (16) are integrally shaped like hyσ
An intermediate disk (21) is provided between the valve cap (14) and the valve cap (14) so as to be able to slide upwardly and downwardly, and the intermediate disk (21) is provided with an axial direction around the valve stem of the main valve (16). A bypass valve (30)'e is provided to open and close a plurality of bypass steam passages (35) formed in the same direction, and a bypass steam passage hole is provided around the bypass valve (30). (22) f: In the formed main steam stop valve,
A main steam stop with a bypass valve, characterized in that buckwheat is protruded from the arm ends of disks (21) corresponding to the number of bypass valves (30) to form a chamber in the bypass steam passage (35) to narrow the steam inlet. valve.