JP2001221008A - Driving device of steam valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam valve driving device allowing the use of lubricating grease in a connecting part between a cross head and a driving lever in a steam valve to reduce abrasion of a bush and a connecting pin thereof. SOLUTION: This driving device of the steam vale has a steam valve body 21, a valve element 22 of a main valve, a valve rod 26, the cross head 27, a stand 24 fitted to the top of the valve element 22 main body for guiding the valve rod 26 through the bush 28, and a lever support 25 fitted to the top of the stand 24 for guiding the cross head. In the driving device, a space surrounded with the stand 24, the cross head 27 and the lever support 25 is formed as a seal structure, and an exhaust system 51 is provided for communicating the space of the seal structure with an external ground capacitor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam valve in a steam turbine power plant, and more particularly, to a steam valve driving apparatus for reducing abrasion of a connecting portion between a steam valve flow control means and a driving means therefor.

[0002]

2. Description of the Related Art Generally, in a steam turbine power plant,
A steam valve is used to regulate the amount of steam flowing into the steam turbine according to the output.

FIG. 7 shows a system diagram of a general reheat steam turbine power plant.

As shown in FIG. 7, in a reheated steam turbine power plant, high-temperature and high-pressure steam generated in a superheater 1 of a boiler passes through a main steam pipe 2, a main steam stop valve 3, and a steam control valve 4. Through the reed pipe 5 into the high-pressure turbine 6, expands into low-temperature steam, passes through the low-temperature reheat pipe 7, is reheated by the reheater 8, and is heated by the high-temperature reheat pipe 9, the reheat steam stop valve 10, It flows into the intermediate pressure turbine 12 through the intercept valve 11 and expands, enters the low pressure turbine 14 through the crossover pipe 13, turns into low pressure and low temperature steam, flows into the condenser 15, and is cooled and condensed. Become.

The condensate is condensed by the condensate pump 16 and the low-pressure heater 1
7. After passing through the deaerator 18, the pressure is increased by the water suction pump 19 to supply water, and the water is returned to the boiler superheater 1 via the high-pressure heater 20.

[0006] The drive mechanism of the steam valve such as the main steam stop valve 3, the steam control valve 4, the reheat steam stop valve 10, the intercept valve 11, etc. of the steam turbine transmits the oil pressure of the oil cylinder piston to the rod and directly operates the valve. There are a method of controlling the lift and a method of controlling the lift of the valve by amplifying the force generated in the oil cylinder by a lever.

FIG. 8 shows a conventional steam valve driving apparatus for controlling the lift of a valve by amplifying a force generated in an oil cylinder by a lever. Note that the steam valve activation device in FIG. 8 shows an example of a system in which a drive shaft (valve rod) penetrates above a valve body.

FIG. 9 shows a detailed structure of the drive device of the steam valve shown in FIG.

In the steam valve shown in FIGS. 8 and 9, the steam flows from the inlet of the main body 21 to the outlet through the throttle body (minimum area) of the valve element 22 of the main valve and the valve seat 23. The flow rate of the steam is controlled by the lift of the valve body 22.

A stand 24 is fixed above the valve element 22 of the main valve. A lever support 25 is fixed to an upper portion of the stand 24. The valve element 22 of the main valve has a valve stem 26.
The valve stem 26 has an upper end connected to the crosshead 27 by threaded portions 26a and 27a.

The valve stem 26 is vertically movably guided by a bush 28 provided inside the stand 24. The crosshead 27 is guided by a bush 29 provided inside the lever support 25.

A spring 30 is provided above the crosshead 27 so that the load of the spring 30 prevents the valve stem 26 from coming off due to the internal vapor pressure of the main body 21.

At the upper part of the stand 24, a seal steam hole 24a is provided in the gap between the bush 28 and the valve stem 26, and is connected to a steam seal system (see FIG. 9).

The crosshead 27 is driven by a drive lever system and hydraulic pressure of an oil cylinder.

The oil cylinder comprises a main body 31, a control oil supply 32,
And a piston 33. When the pressure of the control oil supply 32 acts on the lower surface of the piston 33, the piston 33 overcomes the load of the spring 34 and moves the piston rod 35, the lower lever 36, and the crosshead 27. The passing steam flow rate is controlled by changing the lift of the valve element 22 of the main valve at the lower end.

The connection portion A between the crosshead 27 and the lower lever 36 is connected to the connection pin 37 by a nut 37a. A bush 38 is provided on the crosshead side to support a high load.

The drive lever system includes a piston rod 35, a lower lever 36, a fulcrum lever 39, and an upper lever 4
0, a tension rod 41.

The connection between the lever and the rod is mainly connected by a pin and a bush.

A connecting portion B between the lower lever 36 and the fulcrum lever 39 includes a pin 42 and a nut 42 on the lower lever side.
a, A bush 43 is provided on the fulcrum lever side to support a high load.

The lower lever 36 and the piston rod 3
5 has a pin 44 and a nut 4 on the lower lever side.
4a, a clevis 45 and a nut 45a are provided on the piston rod side (upper end), and a uniball 46 is provided inside the clevis 45 and the nut 45a, so that a high load can be supported.

The bush 28 inside the stand 24
Is prevented from coming off by the ring 54 and the bolt 55 at the upper part of the stand (see FIG. 9).

In the steam control valve having the above configuration, in normal load operation, the load on the turbine constantly changes, so that the lift of the valve element 22 of the main valve constantly changes and the opening and closing operation is repeated. For this reason, on the contact surface between the bush 38 and the connection pin 37 inside the cross head 27, the sliding with a small width is repeated, and the friction causes wear. Since this part becomes as high as around 250 ° C during operation,
High-temperature grease cannot be used, and conventionally, lubrication was carried out with a fixed lubricant as a measure against wear.

[0023]

As described above, the load of the steam control valve always changes during normal operation, and the main valve repeatedly opens and closes. Therefore, the contact surface between the bush inside the crosshead and the connecting pin in the steam control valve is always subjected to friction.

The surfaces of the connecting pins and the sliding surfaces of the bushes are subjected to a hardening treatment such as nitriding. However, this effect treatment cannot withstand repeated friction caused by a high frequency of opening and closing operations, resulting in wear. It is easy to be. As the wear progresses, the gap between the connection pin and the bush increases, and the amplitude of the steam control valve vibration increases. Also, the threaded portion 2 of the valve stem 26
The stress generated in 6a and the like increases, and the possibility of breakage of the valve stem 26 increases.

In addition, recently, it has been required to extend the inspection interval of the steam turbine power plant. In such a case, it is necessary to inspect the long gap between the contact surface between the bush inside the crosshead and the connecting pin in the steam control valve. It is now possible to exceed the allowed value during the interval.

The cause of the difficulty in preventing the abrasion is the high temperature of the contact portion between the bush of the crosshead and the connecting pin in the steam control valve.

That is, in this part, the surface temperature is 25
A high temperature grease (urea-based, etc.) of a general commercial product that has a high temperature of about 0 ° C. and can be lubricated with a grease gun, etc.
(0-200 ° C is the usage limit). For these high temperature greases, the temperature is 150-20.
If the temperature exceeds 0 ° C., a semi-solid (paste) cannot be maintained,
There has been a problem that it is liquefied or vaporized and lost from the friction surface, and lubrication cannot be secured.

For this reason, conventionally, a special lubricant (commercially available) which has been pasted with a solid lubricant (fine particles of copper, nickel, etc.) and a mineral oil has been used.
The solid lubricant remains because it evaporates at around ℃, and when a mixture of mineral oil and solid lubricant is supplied during operation, the oil supply hole is clogged and the solid lubricant cannot reach the gap between the connection pin and the bush. However, there is a problem that the lubrication effect cannot be improved even with additional lubrication.

An object of the present invention is to reduce the wear of the surface of the contact portion between the crosshead in the steam valve, the bush of the drive lever, and the connection pin in the steam valve driving device of the steam turbine power plant. Another object of the present invention is to provide a structure in which the gap between the connection pin and the surface of the bush does not reach an allowable value even when the inspection interval is lengthened, thereby preventing the occurrence of troubles such as vibration due to an excessive gap.

[0030]

According to a first aspect of the present invention, there is provided a driving apparatus for a steam valve, comprising a main body having a steam flow passage and a valve seat, and a valve body of a main valve at a lower end. A possible valve stem, a crosshead screwed to the upper end of the valve stem and driven by a drive lever, attached to the top of the body,
A stand that guides the movement of the valve stem by holding a part of the valve stem through a bush provided on the inside thereof; and a cross-section attached to the upper portion of the stand via a bush provided inside the stand. A lever support for holding the head and guiding the movement of the crosshead, the drive device for a steam valve of a steam turbine power plant, comprising: an upper end of the stand, a lower end of the crosshead, and the lever support. Space that has been sealed
A passage is provided inside the stand or the lever support for communicating the space of the seal structure with an external ground capacitor.

Since the passage and the ground condenser are provided, steam rising between the valve stem and the bush of the stand is discharged to the outside through the passage. The crosshead is prevented from being heated, and high-temperature grease can be used, and the lubrication oil during operation causes wear of the contact part between the crosshead in the steam valve, the bush of the drive lever, and the connection pin. Can be prevented.

The steam valve driving device according to the second aspect of the present invention comprises:
2. The drive device for a steam valve according to claim 1, wherein an oil supply unit that connects an outer peripheral surface of the connection pin and an external lubricant supply source is provided on a connection pin between the crosshead and the drive lever. 3. Things.

The lubricating means enables high-temperature grease to be supplied directly to the contact portion between the cross head, the drive lever bush, and the connection pin in the cooled steam valve.

According to a third aspect of the present invention, there is provided a steam valve driving device,
2. The steam valve driving device according to claim 1, wherein the crosshead is provided with air cooling means for communicating an outer circumference of a bush holding the crosshead and a connection pin of the drive lever with an external cooling air supply source. It is characterized by the following.

Through the air cooling means, cooling air can be sent from an external cooling air supply source to the outer periphery of the bush holding the connection pin. Accordingly, it is possible to prevent the temperature of the relevant portion from becoming high, and it is possible to realize the prevention of wear due to the use of high-temperature grease.

The steam valve driving device according to claim 4 of the present application is
2. The steam valve drive device according to claim 1, wherein a bush for holding the connection pin of the crosshead and the drive lever has a double structure, and the connection pin has an outer peripheral surface of the connection pin and an external lubricant supply source. 3. Or an air cooling means for communicating between the double bush and an external cooling air supply source, or the oil supply means and the air cooling means are provided on the crosshead. Are provided.

Lubricating oil can be supplied from the oil supply means to the outer peripheral surface of the connection pin, and cooling air can be sent between the double bushes from the air cooling means, thereby having advantages of both cooling and lubrication. be able to.

The steam valve driving device according to claim 5 of the present application is
2. The steam valve driving device according to claim 1, wherein the crosshead is provided with air cooling means for communicating an upper space of a screw portion of the valve stem with an external cooling air supply source. is there.

According to the present steam valve driving device, the cooling air can be sent from the external cooling air supply source to the upper space of the screw portion of the valve stem through the air cooling means.

As a result, the entire crosshead is cooled, the temperature of the crosshead can be prevented from increasing, and wear can be prevented by using high-temperature grease.

[0041]

Embodiments of the present invention will be described below with reference to the drawings. In the following description, for the sake of simplicity, the same parts as those in FIGS. 7 to 9 are denoted by the same reference numerals, and description of overlapping parts will be omitted.

FIG. 1 shows a structure around a crosshead of a steam control valve according to a first embodiment of the present invention.

In the first embodiment of the present invention, the stand 24
The space surrounded by the upper end of the cross head 27 and the lower end of the cross head 27 and the lever support 25 is a sealed structure, and a passage 51a is provided inside the stand 24 for communicating the space of the sealed structure with an external ground capacitor. It is.

The above-mentioned seal structure includes an arbitrary seal structure that can be made by those skilled in the art by a known technique. In the present embodiment, a bush 56 is provided at the lower end on the inner side of the lever support 25, and the bush 56 is Another bush 53 to be fitted with 56 is provided.

The space of the seal structure includes a passage 51a,
The flange 51b and a leak air / steam exhaust system 51 composed of a pipe 51c communicate with an external ground condenser.

With the above configuration, the space surrounded by the stand 24, the bush 28, and the crosshead 27 has a negative pressure with respect to the atmospheric pressure, and the steam leaks from the gap between the valve stem 26 and the bush 28 inside the stand, and , The bush 56 below the lever support and the bush 53 below the crosshead
Can be discharged to the ground capacitor.

As a result, the steam accumulated in the space surrounded by the stand 24, the crosshead 27, and the lever support 25 is transferred to the valve stem 26 and the bush 27b at the lower end of the crosshead.
Can be prevented from entering the screw portion 26a of the valve stem 26 and causing pitting corrosion.

Also, the steam leaking from the peripheral surface of the valve stem 26
When flowing into the outer periphery of the crosshead 27, the crosshead 2
7 is heated. According to the structure of the present embodiment, the vapor can be sealed to prevent the temperature of the crosshead 27 from rising.

The upper portion of the stand 24 is provided with a steam seal hole 24a connected to a steam seal system.

In the above embodiment, the passage 51a is provided inside the stand 24. However, the passage 51a may be provided inside the lever support 25.

Next, a second embodiment of the present invention will be described.

FIG. 2 shows a structure around a crosshead of a steam control valve according to a second embodiment of the present invention.

The steam control valve according to the second embodiment of the present invention has the structure of the first embodiment, and supplies lubricating oil to the outer peripheral surfaces of the crosshead 27 and the connecting pin 37 of the drive lever. 52 are provided.

As shown in FIG. 2, in the present embodiment, a central hole for grease is provided at one end of a connecting pin 37 between the crosshead 27 and the lower lever 36, and a lubricating oil is provided around the entire outer diameter of the central portion. A groove is provided so that grease flows from the oil supply groove to the left and right, and grease is supplied to the entire circumference of the connection pin 37.

The lubricating oil supply means 52 includes a grease-filled container 52a for supplying lubricating grease at a head difference.
And an oil supply pipe 52b using a flexible tube or the like
And a joint 52c for the connection pin 37 and a lubrication hole 52d. The grease-containing container 52a may be replaced with a grease gun joint by mechanical force.

According to the present embodiment, as described in the first embodiment, a rise in the temperature of the crosshead 27 is prevented,
Since high-temperature lubricating grease can be used, and the lubricating grease is supplied between the connecting pin 37 and the bush 38 through the above-described lubricating oil supply means 52, lubrication can be ensured and wear of the portion can be reduced. .

Next, a third embodiment of the present invention will be described.

FIG. 3 shows the structure around the crosshead of the steam control valve according to the third embodiment of the present invention.

The steam control valve according to the third embodiment has the structure of the steam control valve of the first embodiment,
Further, an air cooling means 50 is provided for communicating the outer periphery of a bush 38 holding the connection pin 37 with an external cooling air supply source.

The air cooling means 50 comprises a pipe 50a, a pressure reducing valve 50b, a joint 50c, and a hole 50d provided in the crosshead 27.

The air cooling means 50 sends cooling air to the outer periphery of the bush 38 holding the connection pin 37, cools the bush 38 from the outside, cuts off heat conduction from the lower part of the crosshead, and connects the bush 38 with the bush 38. The center connection pin 37 is cooled, and the temperature of the friction surface between the connection pin 37 and the bush 38 is adjusted to 150 using high temperature grease such as urea.
It can be cooled to 200 ° C. or less.

Next, a fourth embodiment of the present invention will be described.

FIG. 4 shows a structure around a cross head of a steam control valve according to a fourth embodiment of the present invention.

The steam control valve according to the fourth embodiment has the structure of the steam control valve according to the first embodiment, and the bush 38 holding the connection pin 37 has a double structure. And an external cooling oil supply source. The crosshead 27 is provided with an air cooling means 50 for communicating between the double bushes 38a and 38b and an external cooling air supply source. Things.

In the fourth embodiment, both the air cooling means 50 and the lubricating oil supply means 52 are provided, but only one of the air cooling means 50 and the lubricating oil supply means 52 is provided. Is also good.

According to this embodiment, the lubricating oil supply means 5
2 and the air cooling means 50 operate separately and independently. Cooling air enters the outer circumferential groove of the inner bush 38a from the center of the outer bush 38b through the ventilation hole 50e,
From this groove, air flows left and right through the minute gap between the inner bush 38a and the outer bush 38b, and the inner and outer bushes 38a,
By cooling the entire 38b, the heat transfer to the central portion can be prevented, and the temperature rise of the connection pin 37 can be prevented.

In the steam valve according to the fourth embodiment, the inner surface of the inner bush 38a is used as a friction surface (sliding surface) with the connection pin 37, and the inner surface of the inner bush 38a is connected to the inner surface of the outer bush 38b. Since the minute gap between them is used as a cooling surface, heat transfer between the inner and outer bushes 38a and 38b can be prevented, and the temperature rise of the central connection pin 37 can be completely prevented. As a result, the grease supply system 52 to the center of the connection pin 37 and the cooling air system 50 to the bush in the crosshead can be connected separately, and the respective functions can be performed without interference.

Next, a fifth embodiment of the present invention will be described.

FIG. 5 shows a structure around a crosshead of a steam control valve according to a fifth embodiment of the present invention.

The steam control valve according to the fifth embodiment has the structure of the steam control valve according to the first embodiment.
Further, an air cooling means 57 is provided for communicating the space above the threaded portion 26a of the valve stem 26 with an external cooling air supply source.

The air cooling means 57 includes a pipe 57a, a pressure reducing valve 57b, a joint 57c, and a hole 57 provided in the crosshead 27.
d. The hole 57d provided in the crosshead 27 is connected to the upper space of the screw portion 26a of the valve stem 26, that is, the upper space 27d of the screw portion 27a of the crosshead 27 on the female screw side.

The cooling air that has flowed into the upper space 27d flows through the screw portion 27a and the bush 27b into the space of the seal structure below the crosshead 27.

As a result, the screw portion 27 of the crosshead 27 is
and the threaded portion 26a of the valve stem 26 is cooled, the strength of the valve stem is improved, and the pressure in the upper space 27d becomes higher than the pressure in the space of the seal structure. Leakage of steam leaking from the vehicle can be reliably prevented.

As a result, the screw portions 26a and 27a are kept in a dry state, and pitting corrosion of the screw portions 26a and 27a due to the moist atmosphere, which is one of the causes of the breakage of the valve stem 26, can be prevented.

Next, a sixth embodiment combining the first to fifth embodiments will be described.

FIG. 6 shows the structure around the crosshead of the steam control valve according to the sixth embodiment.

Since the steam valve according to the sixth embodiment is a combination of the first to fifth embodiments, only the structure thereof is shown in FIG. 6 and the repeated description is omitted.

According to the steam valve driving apparatus according to the sixth embodiment, each of the first to fifth embodiments has the respective configuration, so that the above-described functions and effects of each embodiment can be obtained. be able to.

[0079]

As is apparent from the above description, according to the present invention, the space surrounded by the upper end of the stand, the lower end of the crosshead, and the lever support has a seal structure, and is provided inside the stand or lever support. By providing a passage that communicates the space of the seal structure with the external ground condenser, leaked steam that rises along the valve stem from the steam valve body and heats the crosshead passes through the exhaust system from the seal structure space. Can be discharged outside.
Thus, the crosshead can be prevented from being heated by the steam, and a rise in the temperature of the connection between the crosshead and the lower lever, which is subject to friction, can be suppressed. By suppressing the rise in temperature, it becomes possible to use high-temperature grease, which has not been able to be used conventionally, for the portion, and it is possible to maintain sufficient lubrication and prevent wear between the connection pin and the bush. Further, it is possible to prevent steam from entering the threaded portions of the valve stem and the crosshead, and to prevent the occurrence of pitting corrosion in the relevant portions.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a cross head peripheral portion of a steam valve driving device according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a configuration of a cross head peripheral portion of a steam valve driving device according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a configuration of a cross head peripheral portion of a steam valve driving device according to a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a configuration of a cross head peripheral portion of a steam valve driving device according to a fourth embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing a configuration of a cross head peripheral portion of a steam valve driving device according to a fifth embodiment of the present invention.

FIG. 6 is a longitudinal sectional view showing a configuration of a cross head peripheral portion of a steam valve driving device according to a sixth embodiment of the present invention.

FIG. 7 is a system diagram of a general reheat steam turbine power plant.

FIG. 8 is a diagram showing an entire configuration of a conventional steam valve drive device.

FIG. 9 is a vertical cross-sectional view showing the configuration of the peripheral portion of the structure crosshead in detail of the drive device of the steam valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler superheater 2 Main steam pipe 3 Main steam stop valve 4 Steam control valve 5 Lead pipe 6 High pressure turbine 7 Low temperature reheat pipe 8 Reheater 9 High temperature reheat pipe 10 Reheat steam stop valve 11 Intercept valve 12 Medium pressure turbine 13 Cross Over pipe 14 Low pressure turbine 15 Condenser 16 Condenser pump 17 Low pressure heater 18 Deaerator 19 Water absorption pump 20 High pressure heater 21 Main body 22 Valve element 23 Valve seat 24 Stand 24a Steam seal hole 25 Lever support 26 Valve stem 26a Screw part 27 Cross head 27a Screw part 27b Screw part 28 Bush 29 Bush 30 Spring 31 Body 32 Control lubrication 33 Piston 34 Spring 35 Piston rod 36 Lower lever 37 Connection pin 37a Nut 38 Bush 39 Fulcrum lever 40 Upper lever 41 Tension rod 2 pin 42a nut 43 bush 44 pin 44a nut 45 clevis 46 uniball 50 air cooling means 50a piping 50b pressure reducing valve 50c coupling 50d hole 51 exhaust system 51a passage 51b flange 51c piping 52 lubricating oil supply means 52a grease-filled vessel 52c oil supply Joint 52d Oil supply hole 53 Bush 54 Ring 55 Bolt 56 Bush

Claims (5)

[Claims] 1. A main body having a steam flow passage and a valve seat, a valve rod having a main valve body at a lower end thereof and capable of moving up and down in the main body, and a driving lever screwed to an upper end of the valve rod. A cross head driven by the main body, a stand attached to an upper portion of the main body, and guiding a movement of the valve stem by holding a part of the valve stem via a bush provided inside the main body, and an upper portion of the stand And a lever support that guides the movement of the crosshead by holding the crosshead via a bush provided on the inside of the steam turbine power plant. The space surrounded by the lower part of the cross head and the lever support is a seal structure, and the space of the seal structure is provided inside the stand or the lever support. A drive device for a steam valve, wherein a passage for communicating with a ground condenser is provided. 2. The steam valve drive device according to claim 1, wherein a connection pin between the crosshead and the drive lever is provided with oil supply means for communicating an outer peripheral surface of the connection pin with an external lubricant supply source. A drive device for a steam valve. 3. A steam valve driving device according to claim 1, wherein said crosshead communicates an outer periphery of a bush holding said crosshead and a connection pin of said driving lever with an external cooling air supply source. A steam valve drive device comprising cooling means. 4. The steam valve driving device according to claim 1, wherein the bush for holding the connecting pin of the cross head and the driving lever has a double structure, and the connecting pin has an outer peripheral surface of the connecting pin and an external part. Oil supply means for communicating with a lubricating oil supply source is provided, or air cooling means for communicating between the double bush and an external cooling air supply source is provided on the crosshead, or And a steam valve driving device provided with both the air cooling means. 5. The steam valve driving device according to claim 1, wherein said crosshead is provided with air cooling means for communicating an upper space of a screw portion of said valve stem with an external cooling air supply source. Characteristic steam valve drive.