JP2003027904A - Steam valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam valve capable of compatibly reducing the cost and the size and reducing the steam leakage. SOLUTION: A stop valve 40 comprises a stop valve side valve element 45, and a stop valve side valve stem 47 which is inserted in a bush 46 to open/ close the stop valve side valve element 45. A governing valve 42 comprises a governing valve side valve element 50 which is inserted in the stop valve side valve element 45 to be opened/closed in the same direction as that of the stop valve side valve element 45, and a governing valve side valve stem 48 which is inserted in the stop valve side valve stem 47 to open/close the governing valve side valve element 50. Back sheets 55 and 56 are provided between the stop valve side valve element 45 and the bush 46, and between the governing valve side valve element 50 and the stop valve side valve stem 47.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam valve used for controlling a steam flow in a steam turbine, for example. 2. Description of the Related Art An example of this type of conventional steam valve will be described below with reference to FIG. The steam valve shown in FIG.
When the operation of a steam turbine (not shown) is started, control oil (high-pressure oil) is first supplied to the oil cylinder 3 of the stop valve 1, and the stop valve 1 and the control valve 2 are integrated. The stop valve 1 is fully opened by moving the valve stem 5 and the valve body 6 upward through the paper through the arrow. Accordingly, the steam S can be flowed into the steam turbine from the steam outlet E at any time by opening the control valve 2. Next, control oil is supplied to the oil cylinder 7 of the control valve 2 or discharged from the oil cylinder 7 according to a control signal of the steam turbine, thereby controlling the control valve via the lever 8 and the valve rod 9. The opening of the second valve body 10 is adjusted, and the flow rate of the steam S flowing into the steam turbine is adjusted. Thereby, the rotation speed or the load of the steam turbine is controlled. [0003] When the steam turbine trips, first, the control oil is discharged from the oil cylinder 3 of the stop valve 1 to release the oil pressure that opens the valve body 6, and the valve rod 5 is moved by the reaction force of the spring 11 to the paper space. Push down. Thereby, the valve element 6 is fully closed. Next, the control oil is discharged from the oil cylinder 7 of the control valve 2 to release the pressure at which the valve body 10 is opened.
The valve rod 9 is pushed downward by the reaction force of the
Fully close. By completely closing both the stop valve 1 and the control valve 2 in this manner, the delivery of the steam S is stopped, and the steam turbine is stopped. By the way, in this conventional steam valve, each bonnet 13 of the stop valve 1 and the control valve 2,
Since the valve stems 14 are provided vertically and the respective stems 5 and 9 are inserted from above and below, the size of the valve body is expected to be large, and it is difficult to reduce the cost, and a large installation space is required. Was a problem. To solve such a problem, a steam valve having a structure shown in FIG. 7 is being developed. The steam valve shown in FIG.
Is inserted coaxially into the control valve 20 so that the control valve 2
The stop valve 21 opens and closes in the same direction as the opening and closing direction of 0, and shuts off or permits the flow of steam S, and a valve box 22 accommodating the control valve 20 and the stop valve 21. Note that reference numeral 23 shown in the figure denotes a bonnet, and reference numeral 24 denotes a bush 26 provided on the bonnet 23 and rotatably supporting the valve rod 25 of the control valve 20 in the axial direction thereof. According to the steam valve, when the operation of a steam turbine (not shown) is started, first, control oil (high-pressure oil) is supplied to the oil cylinder 27 of the stop valve 21, and the piston 28 and the lever 2 are supplied.
The stop valve 21 can be fully opened by moving the valve stem 30 and the valve element 31 upward through the paper 9 via the paper.
As a result, the steam S can enter the steam turbine from the steam outlet E at any time. Next, by supplying control oil to the oil cylinder 32 of the control valve 20 or discharging control oil from the oil cylinder 32 according to a control signal of the steam turbine, the control oil is controlled via the lever 33 and the valve rod 25. Valve 20
Of the valve body 34 is adjusted, and the flow rate of the steam S flowing into the steam turbine is adjusted. Thereby, the rotation speed or the load of the steam turbine is controlled. According to this steam valve, the control valve 20
In addition, since the valve rods 25 and 30 of the stop valve 21 can be collectively provided in one valve box 22, the cost can be reduced, and since the valve is compact, it can be installed even in a narrow space. Can play. However, in the conventional steam valve, when the control valve 20 is fully opened in order to maximize the flow rate of the steam S, the valve rod 25 and the bush 26 are not connected to each other. Leakage can be prevented by the back seat. However, when the stop valve 21 is fully opened, the back seat does not work. Therefore, steam flows through the bush 26 through the gap between the valve body 31 and the valve body 34. This leaks into the steam collection pipe 35 of the bonnet 23 through the hood 23, and causes steam loss. More specifically, as shown by the arrow b, the valve element 3
The leaked steam that has entered through the gap between the valve stem 1 and the valve body 34
It flows to the bush 26 outside the valve shaft 25 through the gap between the valve shaft 5 and the valve rod 30, and finally leaks to the steam recovery pipe 35. [0008] Since such a steam leak affects the operation efficiency of the steam turbine, it has been desired to reduce the leak as much as possible. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steam valve capable of achieving both a reduction in cost and size and a reduction in the amount of steam leakage. [0010] The present invention employs the following means in order to solve the above-mentioned problems. That is, the steam valve according to claim 1 includes a stop valve that shuts off or permits the flow of steam, a control valve that controls the flow rate of the steam, and a valve box that houses the stop valve and the control valve. In the steam valve, the stop valve includes a hollow stop valve-side valve body and a hollow stop valve-side valve rod inserted into a bush provided in the valve box to open and close the stop valve-side valve body. Wherein the control valve is inserted into the stop valve side valve body and opens and closes in the same direction as the stop valve side valve body, and is inserted into the stop valve side valve shaft. A regulating valve-side valve stem for opening and closing the regulating valve-side valve body, and when the stop valve and the regulating valve are fully opened, between the stop-valve-side valve body and the bush; and the regulating valve-side valve body. And a back seat is provided between both the stop valve side valve shaft and That. According to the first aspect of the present invention, the drive valve for the stop valve and the control valve can be installed in the same direction by incorporating the control valve inside the stop valve. Cost reduction and compactness can be achieved from the viewpoint of physique and installation state. In addition, by providing the back seat, when the stop valve and the control valve are fully opened in order to maximize the steam flow through the steam valve, for example, steam leaks from between the stop valve side valve body and the bush. If so, the amount of leakage is reduced by the backsheet provided here. Also, even if steam leaks from between the control valve side valve element and the stop valve side valve rod,
The amount of leakage is reduced by the back sheet provided here. In addition, since the control valve is incorporated inside the stop valve, even during the control valve operation, the stop valve can be fully opened so that the back seat between the stop valve side valve body and the bush is effective. The amount of steam leakage from this portion can also be reduced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the steam valve of the present invention, an example in which the present invention is applied to a main valve of a steam turbine will be described below with reference to FIGS. However, needless to say, the present invention is not limited to this. FIG. 1 is a longitudinal sectional view showing the steam valve of the present embodiment. FIG. 2 is a partial side view of a main part of the steam valve as viewed from an arrow A in FIG. Also, FIG.
It is sectional drawing which shows the other principal part of the steam valve, and is an enlarged view of the B section of FIG. 4 is a cross-sectional view showing a part of the main part of the steam valve. FIG. 4A is an enlarged view of a part C in FIG. 3, and FIG. 4B is an enlarged view of a part D in FIG. . FIG.
Fig. 2 is an enlarged view of a part B of Fig. 1 showing the main part of the steam valve,
A state in which the stop valve is fully opened and the control valve is fully closed is shown. As shown in FIGS. 1 and 2, the steam valve according to the present embodiment comprises a stop valve 40 for shutting off or permitting the flow of steam S, and a stop valve driving portion 41 for driving the stop valve 40 to open and close.
A control valve 42 for controlling the flow rate of steam S, and the control valve 4
2 is provided with a control valve drive unit 43 that drives the opening and closing of the valve 2 and a valve box 44 that houses the stop valve 40 and the control valve 42. The stop valve 40 is coaxially inserted into a hollow stop valve side valve body 45 and a bush 46 attached to the valve box 44, and moves in the axial direction to open and close the stop valve side valve body 45. And a hollow stop valve side valve rod 47 to be provided. One end of a link 41b of the stop valve driving section 41 is connected to an upper end 47a of the stop valve side valve rod 47. The stop valve drive section 41 includes an oil cylinder 41a, a piston (not shown) housed in the oil cylinder 41a, and the link for driving the stop valve drive shaft 47 in conjunction with the piston. 41b. Further, the piston is urged by a spring (not shown) so that when the control oil is discharged from the oil cylinder 41a, the stop valve side valve rod 47 is pushed down toward the lower side of the paper of FIG. . Therefore, when the control oil is supplied to the oil cylinder 41a, the piston receives the oil pressure, and the stop valve side valve rod 47 and the stop valve side valve body 45 are pushed up against the urging force of the spring. Valve 40 is opened. Conversely, when the control oil is discharged from the oil cylinder 41a, the stop valve side valve shaft 47 and the stop valve side valve body 45 are pushed down by the urging force of the spring, and the stop valve 40 is closed. . The control valve 42 is coaxially inserted into the stop valve side valve body 45 and opens and closes in the same direction as the stop valve side valve body 45. The control valve side valve shaft 48 is inserted coaxially inside and opens and closes the control valve side valve body 50. The central portion of a link 43b of the control valve driving section 43 is connected to an upper end 48a of the control valve side valve rod 48. The adjusting valve driving section 43 includes an oil cylinder 43a, a piston (not shown) housed in the oil cylinder 43a, and the link for driving an adjusting valve driving shaft 48 in conjunction with the piston. 43b. Further, the piston is urged by a spring (not shown) so that when the control oil is discharged from the oil cylinder 43a, the control valve-side valve rod 48 is pushed downward in FIG. . Therefore, when the control oil is supplied to the oil cylinder 43a, the piston receives the hydraulic pressure, and the controllable valve shaft 48 and the controllable valve body 50 are pushed up against the urging force of the spring. Valve 42 is opened. Conversely, when the control oil is discharged from the oil cylinder 43a, the control valve side valve rod 48 and the control valve side valve body 50 are pushed down by the urging force of the spring, and the control valve 42 is closed. . As shown in FIG. 3, a recess 46a is formed in the inner peripheral surface of the bush 46 so as to form a clearance space with a clearance t between the bush 46 and the outer peripheral surface of the valve stem 47 on the stop valve side. Then, as shown in FIG. 1 and FIG.
The reference symbol a is such that the leaking steam can be sent out to the steam collecting pipe 52 through the hood 51 fixed to the upper part of the valve box 44. Therefore, in order for the leaking steam to flow to the steam collecting pipe 52, it is necessary to enter the concave portion 46a from the portions C and D shown in FIG. However, in the steam valve of the present embodiment,
As shown in FIGS. 4A and 4B, when the stop valve 40 and the control valve 42 are fully opened, between the stop valve-side valve body 45 and the bush 46, the control valve-side valve body 50 and the stop valve side. Since the back seats 55 and 56 are provided on both sides of the valve shaft 47, the amount of steam leakage from the portions C and D can be extremely reduced. More specifically, convex portions 45a and 46a are formed on the stop valve side valve body 45 and the bush 46 at positions covering the periphery of the stop valve side valve shaft 47 so as to abut against each other. By bringing these convex portions 45a and 46a into surface contact with each other, it is possible to increase the surface pressure and improve the sealing performance here. Similarly, convex portions 50a and 47a are formed on the control valve-side valve body 50 and the stop valve-side valve shaft 47 at positions covering the periphery of the control valve-side valve shaft 48 so as to protrude in a direction in which they contact each other. By bringing the convex portions 50a and 47a into surface contact with each other, it is possible to increase the surface pressure and improve the sealing property here. According to the steam valve of the embodiment described above,
For example, when the stop valve 40 and the control valve 42 are fully opened as shown in FIG. 3 in order to maximize the steam flow flowing through the steam valve, the stop valve side valve body 45 and the portion C between the bush 46 Even if steam leakage is likely to occur, the amount of leakage is reduced by the back sheet 55 provided here. Further, even if steam leaks from the portion D between the control valve side valve body 50 and the stop valve side valve rod 47, the amount of leak is reduced by the back seat 56 provided here. Moreover,
As shown in FIG. 5, even when the control valve 42 is in operation, the stop valve side valve element 45 and the bush 46 can be connected. The stop valve 40 can be fully opened so as to make the back seat 55 effective, and the amount of steam leakage from this portion can also be reduced. In the steam valve of the present embodiment described above, the stop valve 40 has the stop valve side valve rod 45 and the stop valve side valve rod 4 inserted into the bush 46 to open and close the stop valve side valve body 45.
7, the adjusting valve 42 is inserted into the stop valve side valve body 45 and opens and closes in the same direction as the stop valve side valve body 45, and the inside of the stop valve side valve rod 47. And a valve stem 48 which is inserted into the opening and closing the regulator valve body 50 to open and close the regulator valve body 50, between the stop valve side valve body 45 and the bush 46, and between the regulation valve side valve body 50 and the stop valve side valve stem 47. The configuration in which the back sheets 55 and 56 are provided for both of them is adopted. According to this configuration, since the control valve 42 is incorporated inside the stop valve 40, a drive device for the stop valve and the control valve can be installed in the same direction as the stop valve 40 and the control valve 42. , From the viewpoint of the physique and installation condition of the valve body,
Cost reduction and compactness can be achieved. In addition, the back sheets 55 and 56 provided between the stop valve side valve body 45 and the bush 46 and between the control valve side valve body 50 and the stop valve side valve rod 47 invade from these contact portions. It is possible to reduce the amount of leaked steam. Therefore, according to the steam valve of the present embodiment, it is possible to achieve both reduction in cost and size and reduction in the amount of steam leakage. In the present embodiment, the case where the steam valve of the present invention is applied to a main valve of a steam turbine has been described as an example. However, the present invention is not limited to this, and is applicable to other steam valves such as a petrochemical plant. Of course, the invention may be applied. In the steam valve according to the first aspect of the present invention, the stop valve has a stop valve side valve body and a stop valve side inserted into the bush to open and close the stop valve side valve body. A valve stem, wherein the control valve is inserted into the stop valve side valve body and opens and closes in the same direction as the stop valve side valve body, and is inserted into the stop valve side valve shaft. A configuration in which a control valve side valve rod for opening and closing the control valve side valve element is provided, and a back sheet is provided both between the stop valve side valve element and the bush and between the control valve side valve element and the stop valve side valve rod. It was adopted. According to this configuration, since a control valve is incorporated inside the stop valve, there is no need to provide a bonnet or the like dedicated to each of the stop valve and the control valve, so that cost reduction and compactness can be achieved. In addition, between the stop valve side valve body and the bush,
By the back seats provided between the control valve side valve element and the stop valve side valve rod, it is possible to reduce the amount of steam leakage that enters and leaks from these contact portions. In addition, since the control valve is incorporated inside the stop valve, even during the control valve operation, the stop valve can be fully opened so that the back seat between the stop valve side valve body and the bush is effective. The amount of steam leakage from this portion can be reduced as well. Therefore, according to the steam valve of the present invention, attaining low cost and compactness,
It is possible to achieve both a reduction in the amount of steam leakage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing one embodiment of a steam valve of the present invention. FIG. 2 is a partial side view of a main part of the steam valve when viewed from an arrow A in FIG. FIG. 3 is a sectional view showing another main part of the steam valve,
It is the B section enlarged view of FIG. 4 is a sectional view showing a part of the essential part of the steam valve, in which (a) is an enlarged view of a part C in FIG. 3, and (b) is a sectional view of FIG.
It is a D section enlarged view of. FIG. 5 is an enlarged view of a portion B of FIG. 1 showing the main part of the steam valve, showing a state in which a stop valve is fully opened and a control valve is fully closed. FIG. 6 is a longitudinal sectional view showing an example of a conventional steam valve. FIG. 7 is a longitudinal sectional view showing another conventional steam valve. [Description of Symbols] S: Steam 40: Stop valve 42: Adjusting valve 44: Valve box 45: Stop valve side valve body 46: Bush 47: Stop valve side valve Shaft 48 ... Adjustable valve side valve shaft 50 ... Adjustable valve side valve body 55, 56 ... Back seat

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Claims (1)

Claims: 1. A stop valve for shutting off or permitting the flow of steam, a control valve for controlling the flow rate of the steam, and a steam valve containing the stop valve and the control valve in one valve box. In the above, the stop valve comprises a hollow stop valve side valve body, and a hollow stop valve side valve rod inserted into a bush provided in the valve box to open and close the stop valve side valve body, The adjusting valve is inserted into the stop valve-side valve element and opens and closes in the same direction as the stop valve-side valve element;
A control valve-side valve rod inserted into the stop valve-side valve rod to open and close the control valve-side valve element, the stop valve-side valve element when the stop valve and the control valve are fully opened. And a back seat provided between the bush and between the control valve side valve body and the stop valve side valve shaft.