JPS5929703A - Control valve - Google Patents

Abstract

PURPOSE:To prevent steam from leaking from the sliding part and a valve stem from bending by fitting a bush in the guide of a steam control valve to provide the interior of the guide in the form of double back seat so as to induce steam to the sliding part of the valve stem. CONSTITUTION:A valve stem 36 to which a valve body 31 is joined is inserted through a guide 34 in the form of a shaft and a bush 46 is fit at the upper end part of the guide 34. The diameter of valve stem 36 increases downward, namely, having the first and the second shoulder 43 and 45, which abut the first and the second back seat 42 and 44 of the guide 34 in watertight state, respectively. The guide 34 has an inlet 40 and an outlet 39 of steam at the lower end part, whereby supplying low-temperature and low-pressure steam. The bush 46 and the two-stage back seat may prevent leak of steam and withstand an impact applied to the valve stem, and the steam supplied from the inlet 40 may restrain steam leak from the sliding part and preheat the valve stem 36 to reduce any excessive thermal stress so that the valve steam may be prevented from bending.

Description

DETAILED DESCRIPTION OF THE INVENTION [Branch J Field of the Invention] The present invention relates to a control valve used for controlling ultra-high temperature and high pressure steam in a steam turbine plant or the like.

[Technical background of the invention]

Figure 1 is a diagram showing the system of a steam turbine flant that uses ultra-high temperature and high pressure as the working fluid. Steam generated in the boiler (1) passes through the main steam pipe (2), Stop valve (
81, ultra-high pressure turbine section (5) via steam control valve (4)
supplied to The steam that has done work in the ultra-high pressure turbine section (5) is returned to the boiler (1) through the first low-temperature reheat pipe, and the steam heated up again here is passed through the first intercept valve (1 The high pressure turbine section (6) (2) is supplied through the first reheat stop valve (a), and the high pressure turbine section (6)
The steam that has done work is returned to the boiler (1) through the second low-temperature reheat pipe (a), and the steam heated up again here passes through the second intercept valve (211, the second It is supplied to the intermediate pressure turbine (7) via the reheat stop valve (support).

The steam that has worked in the medium-pressure evening bin (7) is transferred to the low-pressure turbine (
The 8th stitch is sent to the 2nd station, where it does work and rotates the generator (9), producing electrical output. The steam that has finished its work in the low pressure turbine (8) is collected in a condenser flO), where it is condensed to approximately room temperature. The condensed water is sent to the first low pressure feed water heater (121), the second low pressure feed water heater (181), and the intermediate pressure feed water heater (181) through the condensate pump 01, and during this time, the high pressure turbine section (6), medium pressure turbine y (7
) It exchanges heat with steam drawn from the middle stage of the low-pressure turbine (8) and is returned to the boiler (1) to aid in temperature rise, improving the thermal efficiency of the entire plant. In addition, water drained after heat exchange in the first low-pressure feed water heater (121) is drained through the pipe (121).
The water is returned to the condenser through the pump (12a) and used as condensate, while the water that has been converted into a drain after heat exchange in the second low-pressure feed water heater (19) is returned to the condenser through the pump (17). Pressure feed water heater +14.) C is sent to the water supply and can be reused.

On the other hand, in the intermediate pressure feed water heater (No. 0), the feed water whose temperature has been raised by the extracted steam from the high pressure turbine section (6) is transferred to the first high pressure feed water heater (No. 151) by the feed water pump 080.

The water is sequentially sent to the second high-pressure feedwater heater (16), during which time it is heated by exchanging heat with extracted steam from the ultra-high-pressure turbine section (5) and the high-pressure turbine section (6) one after another, raising the temperature of the boiler (1).
Returned to C1. Also, a first high pressure water heater (15),
In the second high-pressure feed water heater n6>, water that has been turned into a drain.

Feed water heaters (14) s (15
) and play a role in improving plant efficiency.

Live steam stop valve (81, steam control valve (4), first and second intercept valve (+9), arranged in the above system C,
(211 and first and second reheat stop valves @), (4
The steam valves that control the amount of steam and overspeed, such as those in However, the current boiler-generated steam has a pressure of 169 Kg/m and a % temperature of 538°C in a critical pressure plant, and a pressure of 246 KP/lri□ temperature in a supercritical pressure plant.
Although the temperature is 38°C, given the recent energy Ilp and the background of the era of conservation, it is difficult to say that energy sources are being sufficiently conserved at the current stage, and therefore, the steam conditions are currently being reduced. plant is being considered.

In response to such request C2, control valves such as the main steam stop valve and steam control valve, which occupy a central control position for the turbine, are as follows:
Due to the exposure to higher pressures and slag (more than ever), technical issues that must be solved are being raised.

That is, FIG. 2 shows an embodiment of a conventional steam valve, in which a valve seat (831 is provided on the casing body, and the valve seat 33)
A cylindrical strainer 9101 is attached to the outer peripheral edge of the tube. In addition, the upper opening C2 of the casing body υ allows the upper cover (2) 1 to pass through the collar (support)) +2
71, and a gasket +281 for airtightness is inserted between the upper & rigid body and the casing body (321). In addition, a guide bell is installed in the lower part of the casing body (C32) in close proximity to the valve seat (881, and in such a way that the valve seat (881) is not easily pulled out, and is fitted inside the kite) and engages with the valve body (81). A bar mill j is mounted on the shaft. At the upper end of the valve stem, there is a shoulder c (71) cut out, which acts as a stopper when the valve body T811 is fully opened. It is designed to come into contact with (attack).

Furthermore, a leak-off pipe 5) is provided at the bottom of the casing body 1, and is designed to send steam leakage from the sliding part formed by the guide (2) and the valve stem (i) to the outside. There is.

[Problems with background technology]

Therefore, in Fig. 1, the steam generated in the boiler (1) is shown in Fig. 2 (from arrow A to strainer 1).
, flows in the direction of arrow B through the valve body (31). In order to improve thermal efficiency, if the conventional steam conditions are further improved, in the current structure of the steam valve, the sliding part formed between the guide opening and the valve stem side must be precisely machined for airtightness. This is only a temporary measure because it is exposed to high-temperature, high-pressure steam for a very long period of time, causing deformation and steam leakage. Also, from the standpoint of preventing thermal deformation, it is possible to increase the diameter of the valve stem, but if the drive part (not shown) of the valve stem 186) is made larger, the mechanism will become complicated and the drive part may break down. In such cases, there is the inconvenience of not being able to take emergency measures, and if the mechanism becomes complicated, it is difficult to say that it will necessarily be possible to follow the promptness of valve opening and closing.

[Purpose of the invention]

The present invention has been devised from these viewpoints, and prevents steam leakage from the sliding part formed by the guide and the valve stem, and also improves the sliding part from the conventional structure C2. The purpose is to provide an ultra-high-pressure, high-temperature control valve that achieves the desired results simply by adding

[Summary of the invention]

In the present invention, the upper end C nipush of the guide is fitted.

In addition, the inside of the guide is structured as a two-stage back sea, and the sliding part of the valve stem is filled with relatively low-pressure, low-temperature steam, which prevents leakage of steam and prevents bending of the valve stem. I can figure it out.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. 3, in which the same components as in FIG. 2 are given the same reference numerals.

In C2 of the same figure, the symbol (column shows the valve stem to which the valve body (G) 1 is attached at the upper end) is shown, and the valve stem (86) advances downward f2. The first shoulder (U43) and the second shoulder (16) are cut in place to function as a so-called two-stage stopper.For this valve stem side, form a sliding part (1). A guide ■ is provided for this purpose, and a first back sheet μs4, so that the kite (the first 7iW part and the second shoulder part (3) inside the kite) are in good contact and watertight. Second back sheet (14
) is removed, the outer surface of the guide 1341 becomes a C-first trapezoid p in order to increase the mechanical strength toward its base l1.
li WIl, a second trapezoidal part 1 is formed. Therefore, even if the steam flow transiently enters the transonic or supersonic region, the valve stem will remain in the above-mentioned first condition. Second trapezoidal part, H81
11. Ru.

On the other hand, a bushing is fitted to the upper end of the valve stem (part), and the valve body (31) suppresses bending due to impact caused by the steam flow. In addition, the lower end of the guide example) is perforated with a steam inlet and an outlet.

In the control valve configured as described above, the valve stem (861) is moved upward C by a drive unit (not shown), and the valve body (81) is opened C2 as shown in the figure.At this time, steam passes through the valve stem (■) and guides ( Steam will flow into the interior of the support tube, but steam leakage can be prevented because there is a bush fitted to the upper end C of the guide. In addition, even if the bushings are worn out due to long-term use, the first shoulder part (t) directly below the bushings will be removed.
) and the first backsheet decoy are in watertight contact with each other, so steam leakage can still be prevented at the core. Also, when the valve opens, the steam flow enters the transient C1 transonic or supersonic region,
Although a severe impact force acts on the valve stem (86I) and the valve body i8I+, it can be withstood by the bushing and the so-called two-tiered bank sheet provided inside the guide gap.

On the other hand, there is steam at a relatively low pressure and temperature from 14 of the first low-temperature recycler tube shown in Fig. 1 flowing between the inlets of the sliding part. Even if there is steam leaking from the first back sheet (between the bushings) and the first back sheet, it is sealed with water, and this water sealing is good enough to compensate for the leaked steam by 9 minutes.And The steam that has served as a water seal is sent to other equipment through the valve stem 1g) and the outlet 18g).

The water seal also functions as a preheater to prevent bending of the valve stem. In other words, since the valve stem 136) that protrudes from the guide 136) is exposed to high pressure and high temperature, sudden thermal stress may be applied to the valve stem 136), causing local bending of the valve stem 136). be. However, if relatively low-pressure, low-temperature steam is introduced into the sliding portion Hi11, the lower part of the valve stem 131i1 will be preheated, and the generation of extremely high thermal stress will be suppressed.

Or<1. The pressure is 24, which is the current supercritical pressure steam condition.
In order to improve the thermal efficiency of a turbine plant by increasing the temperature of 6 Kv/ldy and 538° C. by 1.1 degrees of iodine, the present invention employs the above structure, so even if the steam conditions are further increased, this Based on this, rapid F/D development is expected.

〔Effect of the invention〕

As explained above, according to the present invention 1, in order to improve the sealing property between the valve stem and the guide of a control valve that controls high-pressure/high-voltage fluid, and to prevent the valve stem from bending, the upper end of the guide is The above problem can be solved by lowering the bushing and making the inside of the guide a two-stage backsheet (2. By providing a water sealing part in the sliding part of the valve stem).

[Brief explanation of drawings]

Figure 1 shows the system of a conventional general reheat steam turbine plant! ¥1, FIG. 2 is a vertical cross-sectional view of a conventional control valve, and FIG. 3 is a vertical cross-sectional view of a control valve according to the present invention C. 1... Boiler 3... Live steam stop valve 4 ・
Steam control valve 5...Ultra high pressure turbine section 6...High pressure turbine section 7...Intermediate pressure turbine 8...Low pressure turbine 19...First intercept valve 20...First reheat stop valve 21 ...Second intercept valve 22...Second reheat stop valve Tagawa valve body 34...Kite: 36...Valve stem 41...Sliding part
42...First back seat 43...First shoulder section...Second back seat 15...Second
Shoulder part 41i... Bush (7317) Agent/patent attorney Kensuke Chika (#1 is one person) 1st WJ Figure 2

Claims (1)

[Claims] In a control valve that controls high-pressure and high-temperature steam using a valve stem l that has a valve body at its upper end and that slides forward and backward along a guide, a bushing is fitted to the guide and the inside of the kite is When configured into a tiered back sheet,
A control valve characterized in that relatively low pressure and low temperature steam is introduced into the sliding part of the valve stem.