JPS6157443B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to steam turbine emergencies and valve failures.

The phenomenon of scale adhesion in the steam passages of steam turbines and the erosion of the steam passages caused mainly by oxidized scales in the boiler superheater and reheater tubes, which are hard and coarse scales that flow into the turbine together with the steam, have a negative impact on turbine cycle performance. It is considered to be one of the factors in deterioration over time. These scales that flow into the turbine mixed with the steam have various properties depending on the subcritical or supercritical pressure, the material of the feedwater heater tube, the method of treating the feedwater, etc.

It is almost impossible to treat the feed water in a manner that does not allow scale to adhere to the steam turbine at all, or to prevent the presence of scale that is so coarse and hard that it corrodes the steam passages of the turbine. While expecting appropriate measures from the boiler side, several methods have also been attempted to proactively prevent or eliminate the inflow of these scales from the steam turbine side. An object of the present invention is to separate coarse and hard scales that erode the steam passage of the turbine from the steam inside a break valve provided at the inlet of the turbine, and to discharge the scale to the outside. The purpose is to provide a structure that can be used in an emergency.

The present invention provides a casing having a steam inlet and an outlet, a steam chamber disposed in the casing, a plurality of holes for passing steam on the opposite side of the inlet, and a surface facing the inlet. A cylinder without the holes on the side where the holes are present, a steam strainer that is attached to the outside of the cylinder on the side where the holes are present and separates coarse scale mixed in the steam fluid from the steam flow, and a cylinder on the side where the holes are not present. A scale collector is attached to the cylinder on the side where the hole does not exist so that the collided scale will not be mixed into the steam flow again, a chamber is located below the scale collector to collect scale, and the scale collected in the chamber is removed from the valve outside. It is characterized by being equipped with piping for discharging water.

FIG. 1 shows the structure of the emergency valve and valve disconnection provided with the present invention. Valve disc 7 is fully open. Steam from the boiler reaches the steam chamber 12 via the steam inlet 4, passes through a strainer 10 cylindrically surrounding the valve disk 7, and a cylinder 11 holding this strainer, and reaches the steam chamber 13. Strainer 1
0 has a hole 10a for steam passage. The upper part of the cylinder 11 is fixed by a cover 2, and the lower part is fixed by a casing 3, and has holes 11 for steam passage. The steam in the steam chamber 13 passes through a throat portion 27 that includes a valve seat 16 that is part of the casing and a sleeve 6 that holds the spindle 8, and reaches the steam chamber 15 and the steam outlet portion 5.

During normal operation, the specific gravity of the coarse and hard scales that erode the steam passages of the turbine is much higher than that of the steam, so the scales that are carried along with the steam flow and reach the steam inlet are always at the steam inlet 4. and collides with the lower part of the cylinder 11. Several collectors 14 (three collectors are provided in FIG. 2) are provided for the purpose of preventing collided scales from being mixed into the steam flow again. The collector 14 is installed at the lower part of the part where the cylinder 11 faces the steam inlet 4 due to the above-mentioned scale flow characteristics.
As shown in FIG. 2, the cylinder 11 facing the steam inlet 4 does not have the steam passage hole 11a or the strainer 10. This protects the strainer 10 from impact forces caused by steam inflow, and
This is to prevent the scale from passing straight ahead. In other words, such a location is the collector 14
It can be said that this is a suitable place to set up. collector 1
The scale that collides with the steam chamber 4 and falls is collected in a chamber 17, which is a recess provided in the steam chamber 12. A hole 18 is provided in the casing 3 to appropriately discharge the scale collected in the chamber 17, and the pipe 1 is provided with a hole 18.
9, connected to a scale discharge pipe consisting of a pipe 22, a valve 23, a pipe 24, a valve 25, and a pipe 26. Since the scale discharge piping is a high-temperature, high-pressure steam system, valves 23 and 25 are provided to make it redundant. The valve 23 serves as a stop valve that is always fully open, and the valve 25 serves as a control valve that opens as appropriate to discharge scale together with steam. The dam 9 is a current plate for the steam flow in the steam chamber 13.

Generally, the places where these scales cause erosion to the steam passage (not shown) inside the turbine are mostly limited to specific places, and the speed of the scales brought in with the steam at this time is It is well known from experience that there is a close relationship. The speed of the introduced scale is determined by the steam flow rate, and the steam flow rate is determined by the turbine steam flow rate.
That is, when an excessive flow velocity temporarily occurs in a particular steam passage under a certain load of the turbine, it is thought that the mixed scale also has a large kinetic energy and causes an erosion phenomenon. Therefore, the timing of opening the valve 25 to discharge the scale is limited to a specific load increase during startup of the steam turbine. That is, the emergency and valve breakage provided by this patent do not significantly impede the operability and efficiency of the conventional turbine.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an emergency valve that is an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the "A"--
It is an "A" sectional view. 3...Casing, 4...Steam inlet section, 10...
...Strainer, 12...Steam room, 14...Collector, 17...Chamber, 19...Piping.

Claims (1)

[Claims] 1. A casing with a steam inlet and an outlet,
disposed in a steam chamber in the casing, and having a plurality of holes on the side opposite to the inlet portion for allowing steam to pass through;
A cylinder without the holes on the side facing the inlet, a steam strainer attached to the outside of the cylinder on the side where the holes exist to separate coarse scale mixed in the steam fluid from the steam flow, and the holes exist. A scale collector is attached to the cylinder on the side where the hole does not exist so that the scale that collided with the cylinder on the side where the hole does not exist will not be mixed into the steam flow again, a chamber located below the scale collector to collect scale, and a chamber where the scale is collected inside the chamber. A steam turbine emergency or valve breakage characterized by having piping for discharging scale to the outside of the valve.