JPH0481214B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is attached to a steam piping system to control the flow rate from the primary side to the secondary side, and to set the fluid pressure on the secondary side to a predetermined value lower than that on the primary side. This invention relates to a pressure-reducing valve for steam that is maintained at a high temperature, and particularly to one that prevents foreign matter from reaching the valve opening of the pressure-reducing valve.

A pressure reducing valve uses a diaphragm made of a circular thin metal plate. The diaphragm is mounted by being sandwiched between two members forming the valve casing. Then, the elastic force of the pressure setting spring is applied to one surface of the diaphragm, and fluid pressure is applied to the other surface by guiding the fluid on the secondary side. Bring the upper end surface of the valve stem into contact with the center of the lower surface of the diaphragm.

Therefore, the diaphragm bends up and down in response to the fluid pressure on the secondary side acting on the lower surface, using the pressure setting spring as a reference value, and the bending displaces the main valve, opening and closing the valve port connecting the inlet and outlet. .

In this pressure reducing valve, if solid foreign matter such as dust or scale gets caught in the valve part, it will not be able to be completely closed, causing the disadvantage that the secondary side pressure will rise to the primary side pressure.

Prior Art Japanese Utility Model Publication No. 49-16599 discloses a device that prevents foreign matter from reaching the valve port of a pressure reducing valve. In this system, a cylindrical screen is arranged between the inlet and the outlet, below the horizontal partition forming the valve port, that is, on the inlet side. Thus, the inlet fluid flows from the outside of the screen to the inside and from the valve ports toward the outlet. At that time, garbage,
Solid foreign matter such as scale is prevented from passing through the screen.

Problems to be Solved by the Invention When a cylindrical screen is used as described above, an annular space communicating with the inlet is formed on the outer periphery of the screen, and the fluid from the inlet flows through the cylindrical screen all around the screen. Since the casing must be allowed to pass through the screen, the casing requires a certain spacing from the screen all the way around the screen, making the casing bulky and costly. Ta.

Further, in the above method, relatively large foreign matter can be captured by the screen, but there is a problem that fine foreign matter passes through the screen.

Furthermore, in pressure reducing valves used in steam piping systems, condensed water flows mixed with steam, but since it does not have a function to remove this condensate before reaching the valve opening, hunting and chattering phenomena occur. There are problems that arise.

Therefore, the technical problem of the present invention is to reduce the size of the casing that surrounds the screen, and to ensure that minute foreign matter and condensate that have passed through the screen are removed from the system before reaching the valve opening of the pressure reducing valve. That's true.

Means for Solving the Problems The technical means of the present invention taken to solve the above problems is to form an inlet and an outlet in a casing, form a valve port in a horizontal partition separating the inlet and outlet, and A horizontal bulkhead on the inlet side of the valve port in a pressure reducing valve in which the main valve, which is placed facing the port, is opened and closed by a diaphragm that bends based on the deviation between the reference value due to the elastic force of a pressure setting spring and the secondary pressure. A tapered screen that expands downward is placed below with its upper end pressed against the lower surface of the horizontal bulkhead and its lower end pressed against the cylindrical inner wall of the casing around the screen, and between the screen and the valve port. A swirling vane is arranged to swirl the fluid, and a drain valve is disposed below the swirling vane.

Effects The effects of the above technical means are as follows.
Since the screen has a tapered shape, an annular space having a triangular cross section can be formed between the outer casing and the outer periphery of the screen even if the outer casing has a cylindrical shape with an inner diameter approximately equal to the outer diameter of the maximum outer diameter portion at the lower end of the screen. This annular space with a triangular cross section allows the inlet fluid to pass around the entire circumference of the screen. At this time, relatively large foreign objects are captured by the screen. The steam, condensate, and fine foreign matter that have passed through the screen are swirled by swirling vanes, and due to the action of centrifugal force, the condensate and foreign matter, which have a mass greater than the steam, are swung out to the outside, where they fall or fall along the surrounding walls. dripping,
It is removed from the system by the drain valve. Steam with a small mass is in the center of the swirling flow and heads toward the valve opening of the pressure reducing valve.

Effect of the invention The present invention produces the following unique effects.

The casing that surrounds the outer periphery of the screen has a cylindrical shape with an inner diameter that is approximately equal to the outer diameter of the maximum outer diameter portion of the tapered screen, that is, the outer diameter of the lower end portion, so that the casing is small and low cost.

Since the screen has a tapered shape that expands downward, the upper end can be pressed against the lower surface of the horizontal bulkhead forming the valve port, and the lower end against the inner wall of the cylindrical casing around the outer periphery of the screen, without using any other mounting parts. It can be placed as follows.

Fine foreign matter and condensate passing through the screen are separated from the steam by centrifugal force and expelled from the system by the time they reach the valve opening of the pressure reducing valve. This prevents foreign matter from getting caught in the valve and prevents hunting. It never happens.

Embodiment An embodiment illustrating a specific example of the above technical means will be described (see FIG. 1 and FIG. 2).

A valve casing 1 forms an inlet 2 and an outlet 3 for fluid. The valve seat member 30 with the valve port 4 formed thereon is attached to the horizontal partition wall. Inlet 2 and outlet 3 communicate through valve port 4 . A main valve 5 is disposed on the inlet side of the valve port 4, that is, on the lower side in FIG. The main valve 5 is pressed against the valve seat member 30 by the elastic force of a coil spring arranged below.

A cylinder 7 and a piston 6 are arranged above the valve port 4. The piston 6 has a groove formed on its outer periphery, into which a piston ring is fitted, and is slidably inserted into the cylinder 7 in an airtight manner. The lower end surface of the piston rod at the lower part of the piston 6 is brought into contact with the upper end surface of the boss of the main valve 5. Further, an orifice 8 is provided on the transverse wall of the piston 6 to communicate the upper and lower spaces thereof. Therefore, the space above the transverse wall of the piston 6 (hereinafter referred to as the piston chamber) communicates with the outlet side through the orifice 8.

A primary side pressure passage 17 communicating between the inlet side and the piston chamber is provided, and is opened and closed by a pilot valve 9. Also,
A diaphragm 20 is provided, and the space below the diaphragm 20 is communicated with the outlet side through a secondary side pressure passage 22. A pressure setting spring 19 is arranged on the upper surface of the diaphragm 20.

Spring receiver 3 attached to the upper end of the pressure setting spring 19
An adjusting screw 31 is provided for displacing the spring 19 to change the elastic force of the spring 19.

A separation unit having a cylindrical partition wall 40 and swirl vanes 41 is arranged below the valve port 4. Reference number 42 is a screen, the details of which will be described later with reference to FIG.

A water reservoir 43 is formed in the lower part, and a drain valve port 45 communicating with a drain passage 44 and a spherical float valve 46 for opening and closing the drain valve port are arranged. Reference number 47 is a float cover that covers the float valve 46.

The operation of the pressure reducing valve described above will be explained. If the pressure on the outlet side is smaller than the value set by the pressure setting spring 19, the fluid pressure acting on the lower surface of the diaphragm 20 is correspondingly smaller, so the diaphragm 20 bends convexly downward, opening the pilot valve 9.
Then, the fluid on the inlet side is introduced into the piston chamber through the primary pressure passage 17, the piston 6 is pushed down, the main valve 5 moves away from the valve seat and opens the valve port 4, and the fluid at the inlet 2 passes through the screen 42. The water passes through the outer peripheral space and central opening of the cylindrical partition wall 40 and flows from the valve port 4 to the outlet 3.

Then, the fluid pressure on the outlet side is set by the pressure setting spring 1
9, the deflection of the diaphragm 20 returns due to the same action as described above, the pilot valve 9 closes, the introduction of fluid into the piston chamber stops, and the fluid in the piston chamber escapes to the outlet side through the orifice 8. The piston 6 moves upward, and the main valve 5 closes the valve port 4.

The fluid at the inlet 2 is swirled by the swirling blades 41, and water droplets are swung outward by the action of centrifugal force, flow down along the inner wall of the water reservoir 43, and flow from the drain port 45 to the drain passage 44 by the action of the float valve 46. automatically excluded.

Next, the structure of the screen 42 will be explained in detail with reference to FIG.

The screen 42 is made by winding a stainless steel thin plate with small holes on one side and forming it into a tapered shape that widens downward. The upper end surface is pressed against the lower surface 53 of the horizontal partition wall in which the mounting hole 52 of the valve seat member 30 between the inlet 2 and the outlet 3 is opened, and the lower end is placed in contact with the cylindrical inner surrounding surface 51 of the valve casing 1. do. Therefore, an annular space 54 having a triangular cross section is formed between the outer periphery of the screen 42 and the valve casing 1, and the fluid at the inlet 2 circulates around the entire outer periphery of the screen 42 through this annular space 54, and passes through the screen 42. It passes through the entire surface of 42.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a pressure reducing valve according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a screen portion. 1... Valve casing, 2... Inlet, 3... Outlet, 4... Valve port, 42... Screen, 54...
annular space.

Claims (1)

[Claims] 1. An inlet and an outlet are formed in the casing, a valve port is formed in the horizontal bulkhead separating the inlet and the outlet, and the main valve placed opposite the valve port is set to the reference value and the outlet pressure by the elastic force of the pressure setting spring. In a pressure reducing valve that opens and closes with a diaphragm that bends based on the deviation between the , a pressure reducing valve for steam that is placed against the cylindrical inner wall of the casing on the outer periphery of the lower end screen, has swirl vanes that swirl the fluid between the screen and the valve port, and has a drain valve disposed below the swirl vanes.