JPS6060374A - Adjusting valve - Google Patents

Abstract

PURPOSE:To prevent generation of errosion between the closure part of a valve body and the seat part of a valve seat by forming a foreign-material catching part which forms a minute slit on the inlet flow-passage side with respect to the seat part of the valve seat. CONSTITUTION:On the inlet flow-passage side with respect to the seat part 17 of a valve seat 15, a foreign-material catching part 34 which forms a constant minute gap G1 is formed between the outer peripheral part 33 of a valve body 25, in the state where the seat part 17 and the closure part 26 are minutely opened or closed each other. Said minute gap G1 is made smaller than the gap G0 formed between the seat part 17 and the closure part 26 in the ordinary state of minutely opened valve. Therefore, the max. throttle part is formed between the outer peripheral part 33 of the valve body 25 and the foreign-material catching part 34 of the valve seat 15, and errosion is generated in this part, and the generation of errosion between the closure part 26 and the seat part 27 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control valve, and in particular, to a separation tank level control valve used in a variable pressure startup bypass system of a steam power station, which is relatively free from foreign matter such as scale in a piping system. The present invention relates to a control valve suitable for easily adjusting or shutting off the pressure and flow rate of high-temperature, high-pressure fluid.

Generally, a control valve includes a casing including an inlet flow path, an outlet flow path, and a valve chamber, a valve seat disposed within the valve chamber of the casing, and a valve seat having a seat portion, and movably disposed within the valve chamber of the casing. The valve body has a closing part that moves toward and away from the seat part of the valve seat, and a variable valve formed between the valve body and the valve seat controls the pressure and flow rate of the fluid that flows in from the inlet flow path. It is continuously adjusted by the constriction part and can be discharged from the outlet channel.

By the way, in the so-called valve slightly open state in which the variable throttle part formed between the valve body and valve seat of the control valve is used for a very short time, the ultrahigh-speed fluid that has been throttled to the maximum flows through the valve. Since it blows between the closing part of the body and the seat part of the valve seat, two lotions are generated due to fluid abrasion on the closing part and the seat part, and as a result, the closing part and the seat part are closed and the control valve is completely closed. At times, large amounts of fluid may leak between the closure and the seat.

Here, conventionally, in order to protect the closing part of the valve body and the seat part of the valve seat from erosion due to fluid abrasion when the control valve is slightly open, the closing part of the valve body and the seat part of the valve seat in the slightly open state are protected. A regulating valve is used in which a clearance area that can define a fluid passage area smaller than the fluid passage area between the valve body and the outlet flow path side with respect to the closing part of the valve body and the seat part of the valve seat is used. In other words, this control valve forms the highest constriction part under the slightly open state in the clearance area, and by causing erosion due to fluid abrasion in this part, erosion to the closing part of the valve body and the seat part of the valve seat is prevented. The aim is to avoid the occurrence of

However, in piping systems equipped with control valves, for example, in piping systems equipped with separation tank level control valves used in transformer start-up bypass systems of steam power plants, foreign matter such as scale can get mixed into the fluid. Therefore, in such a case, the clearance area provided in the control valve becomes a trap for foreign matter. When foreign matter trapped in the clearance area accumulates on the closing portion of the valve body and the seat portion of the valve seat, and the closing portion and the seat portion reach the closed state, the foreign matter may be caught between the closing portion and the seat portion. A blow-by of high-pressure fluid occurs starting from the concave part, and this blow-by causes erosion in which the fluid easily erodes the closing part and the seat part, and as a result, the outlet of the high-temperature, high-pressure fluid from the control valve. The amount of leakage to the flow path side increases over time, causing enormous energy waste.

In fact, in isolated tank level control valves used in variable pressure startup bypass systems at steam power plants, most of the damage to the valve body and valve seat that requires valve disassembly is caused by the above-mentioned closing part. This is due to erosion caused by foreign matter getting caught in the seat.

The present invention protects the closing portion of the valve body and the seat portion of the valve seat from erosion caused by ultra-high-speed fluid without depositing foreign matter between the closing portion and the seat portion of the valve seat when the valve is fully closed. The purpose of the present invention is to protect the closing part and the seat part from erosion due to foreign objects being caught in the valve when the valve is fully closed, and to obtain a safe shut-off state without fluid leakage.

In order to achieve the above object, the control valve according to the present invention has a constant distance between the closing part of the valve body and the seat part of the valve seat under a state where the closing part of the valve body and the seat part of the valve seat are slightly opened or closed. minute 81
The foreign matter trapping section defining the N is provided on the inlet flow path side of the valve seat with respect to the seat section.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a control valve according to an embodiment of the present invention;
FIG. 2 is a sectional view showing an enlarged main part of FIG. 1.

The casing 11 is formed with an inlet passage 12 and an outlet passage 13 that are orthogonal to each other, for example in the horizontal and vertical directions, and a valve chamber 14 is formed at the intersection of the inlet passage 12 and the outlet passage 13. has been done.

A valve seat 15 is integrated into the valve chamber 14 of the casing 11 while being fixed by a lock nut 16 screwed into the casing 11. Note that 17 is a seat portion of the valve seat 15, and a screw tool can be engaged with the lock nut 16 at equidistant positions in the circumferential direction, and a lock par 18 welded to the casing 11 can be engaged with it. An engaging recess 19 is formed.

Further, a valve body guide 2° is integrated into the casing 11 coaxially with respect to the valve seat 15 while being fixed by a retainer nut 21 screwed into the casing 11. In addition,
Between the casing 11 and the valve body guide 20, there is a packing press plate 22 supported on the back side by a retainer nut 21.
A gasket 23 that is held by is attached.

The valve body guide 20 integrated into the casing 11
The valve stem 24 is inserted into the valve stem 24, and the valve body guide 20 is inserted into the valve stem 24.
A valve body 25 integrated at the tip of the valve body can be guided in sliding contact with the valve body 25. That is, the valve body 25 is movable within the valve chamber 14 of the casing 11 in the direction toward and away from the valve seat l5, and the closing portion 2 is capable of coming into close contact with the seat portion 17.
6, and a plug portion 27 having a predetermined contour shape that makes the area of the fluid flow path defined between the valve seats 15 variable as the valve opening degree changes.

Further, a threaded portion 28 is formed at the base end of the valve rod 24 to which a valve opening/closing actuator (not shown) can be connected. Further, a gasket 29 is installed between the valve body guide 20 and the valve stem 24, and the gasket 29 is held under pressure between a gasket retainer 30 and a gasket retainer 32 that is supported from behind by a gasket flange 31.

Therefore, the inlet flow path 1 to the seat portion 17 of the valve seat 15
On the second side, there is a foreign matter trapping part 34 that defines a certain minute gap G1 between the outer circumferential part 33 of the valve body 25 and the seat part 17 and the closing part 26 in a state where the seat part 17 and the closing part 26 are slightly opened or closed. It is poisonous. The minute gap G1 is smaller than the gap Go defined between the seat portion 17 and the closing portion 26 when the valve is in a normal slightly open state. A plurality of annular groove-shaped foreign matter retention portions 35 are formed on the inner peripheral surface of the foreign matter trapping portion 34 in the valve seat 15 .

Note that a relief portion 36 is formed on the outlet flow path 13 side of the valve seat 15 with respect to the seat portion 17, and a relief portion 37 is formed between the closing portion 26 of the valve body 25 and the plug portion 27, and both relief portions are formed. The gap G2 defined between 36 and 37 is larger than the gap GO defined between the seat portion 17 and the closed portion 26 in the above-mentioned normal valve slightly open state.

Next, the operation of the above embodiment will be explained.

By the operation of the valve opening/closing actuator, the valve stem 24 and the valve body 25 are moved in the axial direction, and as shown in FIG. By forming the constriction part, when the fluid that has flowed into the valve chamber 14 from the inlet flow path 12 passes through this constriction part, its pressure,
The flow rate is adjusted and the fluid is discharged from the outlet channel 13. Here, when the valve body 25 moves toward the valve seat 15 by the operation of the valve opening/closing actuator, the gap formed between the plug part 27 and the valve seat 15 is determined by the valve opening degree determined by the contour shape of the plug part 27. and the fluid passage area, and the amount of fluid discharged to the outlet flow path 13 is reduced. Note that the foreign matter 40 in the fluid at this stage smoothly passes through the relatively wide gap defined between the valve seat 15 and the valve body 25.

In the valve slightly open state, as shown in FIG. 3(B), the valve body 25
The outer peripheral part 33 of the valve body 25 reaches the foreign matter trapping part 34 of the valve seat 15, and the valve body 25 is coaxially aligned with the valve seat 15, and the closing part 26 of the valve body 25 and the seat part 17 of the valve seat 15 are aligned coaxially. The gap GO is defined between the outer peripheral part 33 of the valve body 25 and the valve seat 1.
The predetermined minute gap Gl is defined between the foreign matter trapping portion 34 of the valve element 25 and the relief portion 36 of the valve seat 15.
The gap G2 is defined between the two. Under this condition, the area between the outer periphery 33 of the valve body 25, which has the smallest gap, and the foreign matter trapping part 34 of the valve seat 15 becomes the maximum fluid restriction area, and erosion due to the ultrahigh-speed flow of the fluid occurs in this area. Therefore, the closing part 26 of the valve body 25 and the valve seat 1
No erosion occurs between the seat portion 27 and the seat portion 27 of No. 5.

Furthermore, under this condition, foreign matter 40 in the fluid that has flowed into the valve chamber 14 from the inlet flow path 12 is captured on the inlet side of the foreign matter trapping section 34 . In addition, the outer circumferential portion 33 of the valve body 25 and the closing portion 2
6. Foreign matter 40 that has entered between the escape parts 3 and 7 and the foreign matter trapping part 34 of the valve seat 15, the seat part 17, and the escape part 36,
It is discharged to the outlet flow path 13 side on the fluid passing between them.

That is, under this valve slightly open state, no foreign matter 40 is deposited between the closing portion 26 of the valve body 25 and the seat portion 17 of the valve seat 15.

Therefore, in the fully closed state of the valve following the slightly opened state, as shown in FIG. 3(C), the closing portion 2 of the valve body 25 in the closed state
6 and the seat portion 17 of the valve seat 15 are in close contact with each other, making it possible to obtain a safe shut-off state without fluid leakage.

In addition, during the above series of valve slightly opening to valve fully closing processes, the valve body 25
Even if a minute foreign object 40 is caught between the outer peripheral part 33 of the valve seat 15 and the foreign object trapping part 34 of the valve seat 15, the foreign object 40 stays in the foreign object retention recess 35 of the foreign object trapping part 34, and the outer peripheral part 33
This prevents the occurrence of galling between the foreign matter trapping section 34 and the foreign matter trapping section 34.

That is, according to the above embodiment, when the valve is slightly open, the closing portion 26 of the valve body 25 and the inlet flow path 1 of the seat s17 of the valve seat 15 are closed.
By defining a minute gap on two sides, the closing part 26 and the seat part 17 are protected from erosion caused by ultra-high-speed fluid, and it is also possible to prevent foreign matter such as a minute scale from entering the fluid. In addition, these foreign substances 40 do not accumulate on the closing part 26 and the seat part 17 in the valve slightly open state, and the valve fully closed state is obtained while keeping the closing part 26 and the seat part 17 clean. make it possible. Therefore, in the past, the valve seat seat portion and the valve body were the main cause of most of the damage to the valve seat 15 and the valve body 25, and the main factor that caused a large amount of high-temperature, high-pressure energy fluid to leak toward the outlet flow path. It is possible to avoid occurrence of foreign matter biting and erosion in the closing part.

In addition, in the above-mentioned control valve, under the condition where the fluid pressure on the inlet flow path 12 side 1 is much higher than the fluid pressure on the outlet flow path 13 side, the inlet flow path 12 is moved to the side of the valve body 25. Since the outlet flow path 13 is located in front of the plug portion 27 of the valve body 25, the inlet flow path 12 is
, compared to the case where the outlet flow path 13 is arranged in the opposite direction to the valve body 25, the force exerted by the fluid pressure on the valve body 25 becomes a stronger closing blade of the valve body 25, and the valve body 25 The closing part 26 of the valve seat 15 is in complete contact with the seat part 17 of the valve seat 15, and therefore erosion occurs due to the blow-through of high-pressure fluid.
Fluid leakage can be more reliably prevented.

As described above, the control valve according to the present invention has a constant minute gap between the closing part of the valve body and the outer circumferential part of the valve body when the closing part of the valve body and the seat part of the valve seat are slightly opened or closed with respect to each other. A foreign matter trapping portion defining the valve seat is provided on the inlet flow path side of the valve seat with respect to the seat portion. Therefore, when the valve is fully closed, no foreign matter is deposited between the closing part of the valve body and the seat part of the valve seat, and the closing part and the seat part are protected from erosion caused by ultra-high-velocity fluid. However, when the valve is fully closed, it is possible to protect the closing part and the seat part from the generation of two lotions due to foreign objects being caught, and to obtain a safe shut-off state without fluid leakage.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a control valve according to an embodiment of the present invention;
Figure 2 is an enlarged sectional view of the main part of Figure 1, and Figure 3 (
A) is a sectional view of the main part showing the normal opening state of the valve in the same embodiment, FIG. 3(B) is a sectional view of the main part showing the valve in the slightly open state in the same embodiment, and FIG. 3(C) is the same. FIG. 3 is a cross-sectional view of a main part showing a fully closed state of the valve in the embodiment. 11...Casing, 12...Inlet channel, 13...
・Outlet flow path, 14... Valve chamber, 15... Valve seat, 17.
... Seat part, 25... Valve body, 26... Closing part, 3
3...Outer circumference part, 34...Foreign matter trapping part, 35...Four parts for foreign matter retention. Agent Patent Attorney Osamu Shiokawa Figure 3-497- (C) 5

Claims (1)

[Claims] (1) A casing including an inlet flow path, an outlet flow path, and a valve chamber; a valve seat disposed within the valve chamber of the casing and provided with a seat; and a valve seat movably disposed within the valve chamber of the casing and provided with a seat portion. In a control valve having a valve body having a closing part that moves toward and away from a seat part, when the closing part of the valve body and the seat part of the valve seat are slightly opened or closed with respect to each other, A control valve characterized in that a foreign matter trapping part defining a certain minute gap with the outer peripheral part of the body is provided on the inlet flow path side of the valve seat with respect to the seat part. (2. In the control valve according to claim 1,
A control valve with four foreign matter retention areas formed on the inner peripheral surface of a foreign matter trap provided on the valve seat.