JPS61127981A - Operational pressure adjusting device in safety valve - Google Patents

Abstract

PURPOSE:To easily adjust a blowdown pressure, by providing a back pressure adjusting safety valve adapted to open when pressure in a back pressure chamber reaches a predetermined pressure. CONSTITUTION:When a safety valve reaches under a popping pressure, a valve member is lifted to increase a back pressure in a back pressure chamber 14. As a result, a valve member 36 supported by a spring 38 in a back pressure adjusting safety valve 32 is lifted to fully open a valve seat 35 and rapidly decrease the back pressure in the back pressure chamber 14. Therefore, the valve member is lifted to a fixed lift position, and is stabilized. In lowering of the valve member, the back pressure is decreased to close the back pressure adjusting safety valve. As a result, an opening area at a back pressure portion is rapidly decreased, and accordingly, the back pressure is rapidly increased to firmly close the valve member.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention uses a safety valve (4) attached to a device that uses pressure steam, such as a steam boiler, to control the operating pressure during blowing and when the blowing stops. The invention relates to a device for adjusting.

[Conventional technology]

A conventional safety valve is shown in FIG.

In this figure, reference numeral 1 denotes a main body, in which a cylindrical valve seat 2 is fixed in its lower part, an air outlet 3 is provided on the side, and an adjusting wheel 4 is screwed into the outer side of the upper end of the valve seat 2.

5 is a cylindrical guide tube whose upper end is fixed to the inside upper part of the main body 1. An adjustment ring 8 is screwed into the outer lower end of the guide tube 5, and a cylindrical valve holder 6 is movably raised and lowered inside the guide tube 5. The valve body 7 is fixed to the lower end of the valve body.

Reference numeral 10 denotes a valve stem guide fixed on the guide tube 5, through which a valve stem 11 passes through the center of the guide so as to be freely movable up and down.

Reference numeral 12 denotes a lid fixed on the main body 1. The lower part of this lid 12 becomes a back pressure chamber 14, and this back pressure chamber 14 and the inside of the guide cylinder 5 are connected through a plurality of through holes 15 provided in the valve stem guide 10. It's communicating.

Further, as shown in FIG. 4, a lid 12 through which the valve stem 11 passes
A central orifice 16 is provided in the center of the lid 12.
A side orifice 18 having an exhaust pipe 17 is provided on the − side.

Further, there is an exhaust pipe 20 having a needle valve 19 as a throttle valve for adjusting back pressure.

A plurality of legs 22 and a support base 23 are integrally formed on the M12, and a spring box 24 is fixed thereon.

The valve rod 11 passes through the spring box 24, and a coiled spring 26 is fitted on the outside thereof.The lower end of the spring box 24 is supported by a spring receiver 27 that moves up and down with the valve rod 11, and the upper end is held down by a spring retainer 28.

Reference numeral 30 denotes a tubular adjustment screw screwed into a screw hole at the upper end of the spring box 24, through which the valve rod 11 passes freely up and down, and the lower end of the screw 30 is in contact with the spring retainer 28.

In the conventional safety valve as described above, when the steam pressure of a pressure device such as a boiler rises and reaches the blowout pressure of the safety valve, the load of the push-up blade and the spring 26 applied from inside the valve seat 2 to the valve body 7 is balanced. As a result, a slight gap is created between the mating surfaces of the valve body 7 and the valve seat 2, and steam begins to leak from the valve seat surface. Steam is accumulated in the charged chamber formed by the upper end of the ring 4, and this pressure rapidly increases the hot water valve force applied to the valve body 7, causing the valve body 7 to rise instantaneously and steam to be blown out from the valve seat opening.

When the steam begins to blow out vigorously in this way, the valve body 7 maintains a stable lift by reaching a specified lift due to the reaction force of the blown steam and the static pressure applied to the pressure-receiving surface of the cylinder holder 6.

However, if the action of the back pressure chamber 14 becomes excessive, it may cause chatter, so it is necessary to adjust the back pressure appropriately. .

Next, as mentioned above, when the valve body 7 of the safety valve rises to the specified lift and the steam pressure of the device decreases, the restoring force of the spring 26 overcomes the hot water valve force and the valve body 7 descends, causing the valve seat 2 and close the valve.

[Problem that the invention seeks to solve]

The pressure at the time of the above-mentioned blow-off must be adjusted to approximately below the blow-out pressure and above the normal pressure within the device.

Such adjustment is performed using the upper control wheel 8 and the needle valve 19 provided in the back pressure chamber 14, but this adjustment is extremely difficult and must be adjusted to a blowdown pressure of 4% or less (relative to the blowout pressure). This is not an easy task, and it is nearly impossible for an inexperienced person to adjust the downflow to less than 4%.

The reason why it is difficult to adjust the stop pressure is that while the safety valve is blowing, a back pressure regulator such as the needle valve 19 stabilizes the valve body 7 at a specified lift, and when the pressure reaches a low pressure near the stop pressure, the back pressure regulator The point is that a single back pressure adjustment device must perform contradictory tasks such as having to operate in the opposite direction.

The object of the present invention is to make it possible to easily reconcile such contradictory matters.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention is provided with a back pressure adjustment safety valve that opens when the valve body is pushed up during blowing and a predetermined pressure is reached in the back pressure chamber. be.

[Effect]

Since the present invention has the above-described structure, when the safety valve performs the blowing operation, the back pressure adjusting safety valve is fully opened and the valve body is smoothly raised by the specified lifter and stabilized.

In addition, the back pressure safety valve closes near the end of the blow, so the back pressure increases near the end of the blow, and even if the opening of the throttle valve remains constant, the back pressure increases, which has a large effect of closing the valve body, and the blowdown pressure increases. The blowout pressure can be easily adjusted to 4% or less.

〔Example〕

FIG. 1 shows one embodiment of the present invention, and the structure of the safety valve is almost the same as that of the conventional example shown in FIGS. 2 and 3, so the same parts are given the same reference numerals.

In FIG. 1, a safety valve 3 for adjusting back pressure is installed at the outer end of the exhaust pipe 31 in the part where the conventional side orifice was installed.
2 will be provided.

The safety valve 32 can be of any type, but in the illustrated example, a female thread at the lower end of the spring box 33 having an exhaust zero angle is screwed into a male thread at the outer periphery of the upper end of the exhaust pipe 31. The valve stem 37 of the valve body 36 that closes the valve body passes through a guide hole at the upper end of the spring box 33, and the spring 3 fitted on the outside of the valve stem 37 passes through the guide hole at the upper end of the spring box 33.
8 to press the valve body 36 onto the valve seat 35. This spring 38 is supported by a spring retainer 4o at the lower end of an adjustment screw 39 screwed into the upper end of the spring box 33 to enable adjustment.

Next, the operation will be explained, and the explanation of the operation of the parts other than FIG. 1 will be explained based on FIG. 2.

When the steam pressure of a device such as a boiler increases and reaches the blowout pressure of the safety valve, the action in the vicinity of the valve chamber 2 is the same as in the conventional example.

However, in the back pressure chamber 14, as the back pressure increases due to the rise of the valve body 7, the spring 3 of the back pressure adjustment safety valve 32 increases.
The valve body 36 supported by the valve body 8 is pushed up and the valve seat 35 is fully opened, the back pressure in the back pressure chamber 14 rapidly decreases, and the valve body 7 rises to a specified lift and becomes stable.

In this way, the safety valve is fully opened, steam is blown out, the steam pressure inside the device is reduced, and when the valve body 7 is lowered, the back pressure is also lowered, so the back pressure adjustment safety valve is closed, and the opening area of the back pressure section is Since the pressure decreases rapidly, the back pressure suddenly increases, and the valve body 7 is firmly closed.

Although the embodiment includes the central orifice 16 and the needle valve 19, one or both of these may be omitted and only the back pressure adjustment safety valve 32 and the orifice 16 or one needle valve, or the back pressure adjustment safety valve 32 may be used. In some cases, only.

〔effect〕

As described above, this invention provides a safety valve having a back pressure chamber, which is provided with both or one of an orifice and a throttle valve, or omit these and is provided with a safety valve for adjusting back pressure that blows out at a low pressure. The safety valve is fully open,
When the engine stops blowing, this safety valve is fully open, so if a throttle valve is provided, the only adjustment of the throttle valve is the adjustment of the stop pressure.

Therefore, the adjustment is much easier than in the conventional device, which requires both stabilization during blowing and adjustment of the end-of-air pressure using a single throttle valve.

[Brief explanation of drawings]

Fig. 1 is an enlarged vertical sectional front view of the main parts showing one embodiment of the present invention, Fig. 2 is a longitudinal sectional front view of a conventional safety valve, and Fig. 3 is a vertical sectional front view of a conventional safety valve.
FIG. 4 is an enlarged longitudinal sectional front view taken along line B-B in FIG. 3. 1... Main body, 2... Valve seat, 3... Air outlet, 5...
... Guide cylinder, 6 ... Cylinder anchor ■ Luda, 7 ... Valve body, 1
4... Back pressure chamber, 16... Central orifice, 1
8... Side orifice, 19... Needle valve as an example of a throttle valve, 26... Spring, 32... Safety valve for adjusting back pressure. Patent applicant: Fukui Seisakusho Co., Ltd. Agent: Kama 1) Text 2 Figure 2

Claims (1)

[Claims] A valve seat communicating with a pressure device such as a boiler is provided at the lower part of the main body with an air outlet on the side, and a cylindrical valve that can be raised and lowered is placed in a guide cylinder provided at an appropriate distance above the valve seat. A holder is provided, and at the bottom of this valve holder, a valve body that is pressed onto the valve seat is fixed by a load such as a spring, and at the top of the main body, a back pressure chamber that communicates with the inside of the guide cylinder is provided, and the back pressure in this back pressure chamber is An operating pressure adjustment device for a safety valve equipped with a back pressure adjustment safety valve that opens when the valve body is pushed up during blowing and reaches a predetermined pressure in the back pressure chamber.