JPH04216109A - Pressure reducing valve with temperature regulating function - Google Patents

Abstract

PURPOSE:To enable a pressure reducing valve which maintains the pressure of a fluid on the secondary side at a desired level to also lower the temperature of a superheated steam on the primary side to a desired level when the pressure of the superheated steam is reduced. CONSTITUTION:In a pilot type pressure reducing valve, temperature responsive valve 26 which is, by the action of a bimetal 36, closed when the temperature of a fluid passing through a passage 20 is higher than a set temperature and opened when the temperature is lower than the set temperature is provided in the passage 20 which leads a primary-side fluid to a space on a piston 14. Then, by setting the valve 26 at the saturated temperature of the primary-side steam pressure by means of an adjusting screw 38, the valve 26 is opened so that the primary-side fluid can act on the upper surface of the piston 14 when the steam temperature is lower than the set temperature and, as a result, the pressure reducing valve is opened by the driving force of the piston 14 and the primary-side steam is made to flow to the secondary side. In addition, when the primary-side steam becomes superheated steam at temperature higher than the saturated temperature, the valve 26 is closed and no primary- side fluid is supplied to the upper surface of the piston 14. As a result, the pressure reducing valve is closed and the fluid does not flow. Therefore, the primary-side steam temperature is lowered by radiation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure reducing valve for steam that maintains a fluid pressure on a secondary side at a desired set pressure, and more particularly to a pressure reducing valve having the function of setting a pressure and setting a temperature at the same time.

0002

[Prior art] A conventional pressure reducing valve
This will be explained with reference to the publication. The elastic force of the pressure setting spring is applied to the upper surface of the diaphragm, and the secondary side pressure is applied to the lower surface, and the balance of both forces opens and closes the pilot valve provided in the passage communicating the primary side and the space above the piston.

By opening and closing the pilot valve, fluid on the primary side acts on the upper surface of the piston to generate driving force. The driving force of the piston operates the main valve connected to the lower part of the piston to open and close the valve port, allowing fluid from the primary side to pass to the secondary side. When the desired pressure is reached on the secondary side, the pilot valve is actuated in the closing direction via the diaphragm, thereby throttling the valve opening.

0004

[Problems to be Solved by the Invention] Generally, when saturated steam on the primary side is reduced in pressure with a pressure reducing valve, the pressure is at the set pressure, but the temperature becomes higher than the saturation temperature for the set pressure. In other words, it is well known that it becomes superheated steam, but
When the saturated steam on the primary side is depressurized at a not-so-large decompression ratio, the degree of superheating is slight and poses no problem in actual use. However, when the pressure reduction ratio is particularly large and two-stage pressure reduction is performed, the primary side of the second pressure reduction valve is always superheated steam as mentioned above, and this superheated steam is further reduced in pressure, so the pressure is reduced. The steam becomes even more superheated, making it difficult to obtain the desired secondary side temperature. Therefore, in order to obtain steam at the required temperature, water is injected into the superheated steam using a control valve to reduce the temperature. In other words, it is easy to reduce the pressure of steam to obtain a desired pressure, but it is difficult to obtain a desired temperature.

[0005] Therefore, the technical problem of the present invention is to enable the temperature to be reduced to a desired temperature when the pressure of superheated steam on the primary side is reduced by a pressure reducing valve.

[0006]

[Means for Solving the Problems] The technical means of the present invention taken to solve the above problems is that in a pilot type pressure reducing valve, the passage for introducing the primary fluid into the space above the piston is A temperature-responsive valve is installed that closes when the temperature of the fluid passing through it exceeds a set temperature and opens when the temperature falls below.

[0007]

[Operation] The set temperature of the temperature-responsive valve is set to, for example, the saturation temperature of the steam pressure on the primary side of the pressure reducing valve. If the steam temperature is below the set temperature, the response valve opens to allow the primary side fluid to act on the upper surface of the piston, and the generated driving force of the piston opens the valve opening to transfer the primary side steam to the secondary side. flow to At this time, since the steam temperature on the primary side is the saturated temperature, the secondary side is also slightly overheated steam.

[0008] When the steam on the primary side becomes superheated steam and becomes higher than the saturation temperature, the temperature-responsive valve closes and the fluid on the primary side is no longer supplied to the upper surface of the piston, so the valve port closes and the fluid does not flow. do not have. When the fluid flow stops, the temperature of the steam on the primary side decreases due to heat radiation, and as a result, the temperature-responsive valve opens, opening the valve port as described above and allowing the fluid on the primary side to pass to the secondary side. Then, if the temperature rises again, the above is repeated, and this is performed continuously.

[0009]

[Example] An example showing a specific example of the above technical means will be described (see FIG. 1). The entire casing as a pressure reducing valve is a spring case A containing a pressure setting spring 52.
, a valve case B in which a pilot valve 24 is arranged, a main body C in which a piston 14, a cylinder 16, and a valve seat member 8 are housed, and a holder D. This will be explained in more detail below.

[0010] Main body C has inlet 2, valve port 4, and outlet 6.
The inlet 2 connects to a high pressure fluid source on the primary side and the outlet 6 connects to a low pressure region on the secondary side. The valve port 4 is formed by a valve seat member 8, and the valve seat member 8 enters from the lower part of the main body C and is screwed into the interior thereof. The main valve 10 is placed on the inlet side end of the valve 46 and is elastically biased by a coil spring 12, and the main valve shaft 10a is slidably inserted into a holder D placed at the bottom of the main body C.

The cylinder 16 into which the piston 14 is slidably inserted is arranged to be inserted from the upper opening of the main body C, and the piston rod 14b is passed through the valve port 4 and inserted into the main valve 1.
Bring it into contact with the center protruding rod of 0. Reference number 18a,b
is the piston ring. The lower surface of the piston 14 and the piston rod 14b are connected by a substantially hemispherical surface, and an orifice 14c is opened that communicates between the two surfaces.

A pilot valve 24 biased in the valve closing direction by a biasing spring 22 is disposed in a valve case B in a primary pressure passage 20 communicating between the inlet 2 and the upper space of the piston 14, that is, the piston chamber 14a. A temperature responsive valve 26 is provided in the passage 20 communicating the inlet 2 and the pilot valve 24. The temperature responsive valve 26 includes a valve body 30 that opens and closes the responsive valve port 28;
A bimetal 36 that biases the valve body 30 to open and close by bending and contracting depending on the temperature, an adjustment screw 38 that adjusts the set temperature by changing the biasing force to the bimetal 36, and the valve body 3
It is composed of a spring 34 that biases the valve in the valve opening direction, and a holder 32.

The diaphragm 40 is mounted with its outer peripheral edge sandwiched between the flange 42 of the spring case A and the flange 44 of the valve case B, and the space below the diaphragm 40 communicates with the outlet 8 through the secondary pressure detection passage 46. do. The head end surface of the valve stem 48 of the pilot valve 24 is brought into contact with the lower center surface of the diaphragm 40, and a coil spring 5 for pressure setting is attached to the upper surface of the diaphragm 40 via a spring seat 50.
2 into contact with each other, and then tighten the adjustment screw 54 onto the spring case A.
Attach with screws.

The operation will be explained below. The pressure reducing valve of this embodiment is an example used as a second pressure reducing valve in the case of two-stage pressure reduction. First, the set temperature of the response valve 26 is set to the saturation temperature of the primary steam pressure using the adjusting screw 38. In other words, the valve opens when the temperature is below the saturation temperature and closes when it is above the saturation temperature. When the adjustment screw 54 is turned left or right, the elastic force of the pressure setting spring 52 that pushes down the diaphragm 40 changes. This pressure setting spring 3
Using the elastic force of 8 as a reference value, the diaphragm 40 bends in response to the secondary pressure acting on its lower surface, displacing the valve rod 48 and opening and closing the pilot valve 24.

At this time, if the fluid temperature is at or below the saturation temperature, the primary fluid pressure is introduced into the piston chamber 14a,
The piston 14 is driven to displace the main valve 10,
Fluid at inlet 2 flows through valve port 4 to outlet 6. In this way, when the fluid pressure on the secondary side decreases, the valve port 4 opens, and when it increases, it automatically operates to close. When the primary fluid is at the saturated temperature, the degree of superheating of the secondary steam is slight, so there is virtually no problem because the temperature drops to near the saturated temperature due to heat radiation on the way to the steam-using equipment.

Since the temperature-responsive valve 26 closes when the fluid temperature on the primary side exceeds the saturation temperature, the pressure in the piston chamber 14a does not increase even if the pilot valve 24 is open, and the valve port 4 closes. Valve to stop fluid flow. When the flow stops and the temperature of the fluid decreases due to heat radiation and reaches the saturation temperature, the response valve 26
The valve opens and the valve port 4 opens again. This operation is performed continuously rather than intermittently, and almost saturated steam flows to the secondary side.

The above is an example in which the set temperature is the saturation temperature, but the steam temperature on the secondary side can be arbitrarily set by setting it higher than the saturation temperature.

In the above embodiment, if the pilot valve 24 is kept open at all times, it can be used as a pilot type temperature control trap. In other words, the temperature of the condensate is set to 36
When the temperature is detected to be lower than the set temperature, the piston 14 is operated to open the valve port 4 and a large amount of condensate can be discharged.

[0019]

[Effects of the Invention] According to the present invention, it is possible to reduce the pressure of the secondary side steam to a desired temperature, and at the same time, it is possible to reduce the temperature to a desired temperature. High-quality steam can be easily produced without the need for new equipment.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a pressure reducing valve according to an embodiment of the present invention.

[Explanation of symbols]

2 Entrance 6 Exit 14 Piston 16 Cylinder 24 Pilot valve 26 Temperature-responsive valve

Claims (1)

[Claims] Claim 1: In a pilot type pressure reducing valve, a passage for introducing primary fluid into the space above the piston is provided with a temperature at which the valve closes when the temperature of the fluid passing through the passage exceeds a set temperature and opens when the temperature falls below. A pressure reducing valve with a temperature control function characterized by the arrangement of a response valve.