RU180055U1 - AUTOMATIC PROTECTIVE VALVE DIRECT ACTION - Google Patents

Abstract

The direct-acting automatic safety valve has: a hollow axisymmetric body with two hydraulically separated mirror-symmetric compensation chambers; side fittings for connecting cameras to the bypass pipes of the protected valve on different sides of the locking element; end fittings for connecting cameras to the cavity of the valve being protected, equipped with saddles at the joints with the cameras; coaxial rods, which are located inside the specified housing with a gap between their adjacent ends, have spools at opposite ends and together with the saddles serve as the first and second valves, respectively; and means for axial movement of the rods for locking the shutters with the open valve and unlocking one of them when critical pressure is reached in the cavity of the closed valve. To prevent the simultaneous departure of the rods from the seats when a critical pressure is reached in the cavity of the closed valve between the axial displacement means of the said rods, an elastic stiffener is inserted. 2 s.p. f-ly, 4 ill.

Description

Technical field

The utility model relates to the design of direct-acting automatic safety valves for equipping mainly wedge, parallel and slide gate valves used in cooling systems of nuclear reactors, in oil and product pipelines and in piping piping of boilers of thermal power plants and some chemical apparatuses.

State of the art

It is well known that gate valves have closed cavities for accommodating locking elements removed from contact with seats. In the “open” position, these cavities communicate with the space of the inlet and outlet nozzles of the gate valves and therefore, in the “closed” position, they are always filled with the working medium. Naturally, when heated, the pressure inside such cavities increases due to the thermal expansion of the portions of the working media contained in them and that an uncontrolled increase in pressure can lead to more severe accidents, the more dangerous the working environment.

Therefore, the valves are equipped with automatic safety valves to relieve excess pressure when a predetermined critical value is exceeded.

Such valves must satisfy the requirements of reliability and safety.

Despite the rapid development of microelectronics? Indirect valves obviously do not correspond to the first requirement with respect to the indicated technical field, since disconnecting an external power source can lead to an accident in a hydraulic system that is protected against overpressure (see, for example, RU 2517951 issued to “Digital indirect safety valve with electric control ").

Direct-acting valves are, in principle, more reliable, but to ensure safety, their type and specific design must be linked to the properties of the working media and the characteristics of the protected hydraulic systems.

Thus, the drain valve of the oxidizer tank according to RU 2521431 is quite suitable for bleeding small portions of evaporated liquid oxygen into the atmosphere. However, if the tank is designed to store such an aggressive and toxic oxidizing agent as nitrogen oleum (that is, a solution of nitrogen dioxide in concentrated nitric acid), then this valve cannot provide safety.

If the safety valves are designed for nuclear power plants, their design must comply with the very strict “Rules for the design and safe operation of equipment and pipelines of nuclear power plants (NP-089-15). In particular, the safety valves must be operable at a temperature of the working medium up to 450 ° C, exclude its bleeding outside the hydraulic system and work equally in direct and reverse mode.

A direct-acting automatic safety valve is already known from UA 112480 U, which largely complies with the specified requirements and is closest to the valve proposed further in technical essence. Known valve has:

hollow axisymmetric housing with two mirror-symmetric compensation chambers hydraulically separated from one another;

lateral (in particular, radially oriented) fittings that are designed to connect these cameras to the bypass pipes of the protected valve on opposite sides of its locking element;

end fittings, which are designed to connect these cameras to the cavity of the valve being protected and are equipped with saddles at the joints with these cameras;

coaxial rods, which are located inside the specified housing with a gap between their adjacent ends, have spools at opposite ends corresponding to the indicated saddles, and together with the saddles serve as the first and second valves, respectively;

means for axial movement of said rods for locking both gates with an open valve and unlocking one of them when critical pressure is reached in the cavity of a closed valve. These means in the prototype are in the form of bellows or spring-loaded membranes, which serve as separators of the compensation chambers.

Such a protective valve with an open valve does not affect its operation, because the pressure in all cavities of the valve and valve is the same. If the valve is closed, then the pressure in that nozzle, which is connected to the pressure line, is higher than the pressure in the second nozzle connected to the empty drain line.

According to the well-known inventive concept, when the critical pressure in the cavity of the closed gate valve is reached, it, together with the pressure in the pressure port, moves the corresponding rod from its seat by the size of the gap between the adjacent ends of the rods, ensuring that part of the working medium is discharged from the valve cavity into the corresponding compensation chamber and the pressure line and pressure the second rod to its saddle from the drain line.

Unfortunately, an experimental test of the operability of the known protective valve showed that with a free gap between adjacent ends of the rods, their simultaneous displacement towards one another and, accordingly, the simultaneous opening of both shutters are not excluded. This adverse effect is all the more noticeable the lower the pressure in the discharge pipe relative to the pressure in the valve cavity.

Summary of utility model essence

The utility model is based on the task of eliminating the possibility of the simultaneous departure of the rods from the seats when the critical pressure in the cavity of the closed gate valve is reached, to create a significantly more reliable direct-acting automatic safety valve.

The problem is solved in that in an automatic protective valve direct acting, having:

hollow axisymmetric housing with two mirror-symmetric compensation chambers hydraulically separated from one another;

lateral fittings, which are designed to connect these cameras to the bypass pipes of the protected valve on different sides of its locking element;

end fittings, which are designed to connect these cameras to the cavity of the valve being protected and are equipped with saddles at the joints with these cameras;

coaxial rods, which are located inside the specified housing with a gap between their adjacent ends, have spools at opposite ends corresponding to the indicated saddles, and together with the saddles serve as the first and second valves, respectively; and

means for axial movement of said rods for locking both gates with an open valve and unlocking one of them when critical pressure is reached in the cavity of a closed valve,

according to inventive concept

between the means of axial movement of these rods inserted elastic stiffener.

An automatic safety valve having the indicated set of essential features is much more reliable in comparison with the prototype, since the elastic stiffening element keeps the shutter on the drain pipe side locked until the mentioned gap between adjacent ends of the rods is selected.

The first and second additional differences consist, respectively, in the fact that the elastic stiffening element is made either in the form of a spiral spring segment covering the gap zone between adjacent ends of the rods, or in the form of a pair of counter-oriented disk springs, each of which is fixed relative to one of the rods.

The specialist understands that the above and other additional differences can be used in arbitrary combinations with the main inventive concept, which determines the scope of rights.

Detailed description of utility model

Further, the essence of the utility model is illustrated by a detailed description of the design and operation of the improved valve with reference to the drawings, where in longitudinal sections the plane of symmetry in combination with the valve shows:

in FIG. 1 - the simplest automatic protective valve with pistons as means of axial movement of the rods and a spiral spring as an elastic stiffener;

in FIG. 2 - elastic stiffener in the form of a pair of Belleville springs;

in FIG. 3 - automatic safety valve with bellows as a means of axial movement of the rods;

in FIG. 4 - automatic safety valve with membranes as means of axial movement of the rods.

An automatic direct-acting protective valve in any embodiment of the inventive concept has (see Fig. 1):

hollow axisymmetric housing 1 with two hydraulically separated from each other mirror-symmetric compensation chambers 2 and 3;

side fittings 4 and 5, which are designed to connect these cameras to the bypass pipes of the protected valve on opposite sides of its locking element;

end fittings 6 and 7, which are designed to connect chambers 2 and 3, respectively, to the cavity of the valve being protected and are equipped with unmarked seats especially at the joints with these chambers;

coaxial rods 8 and 9, which are located inside the housing 1 with a gap between their adjacent ends, have spools 10 and 11 at the opposite ends corresponding to the said saddles, and together with them serve as the first and second valves;

means 12 and 13 of axial movement of the rods 8 and 9 for locking both shutters with an open valve and unlocking one of them when critical pressure is reached in the cavity of the closed valve and

an elastic stiffener 14, which is inserted between the means 12 and 13.

In the simplest case (see Fig. 1), the means 12 and 13 have the form of pistons that are rigidly connected to the rods 8 and 9 and directly seal the compensation chambers 2 and 3, and the elastic stiffener 14 has the form of a spiral spring segment covering the gap zone between the adjacent ends of the rods 8 and 9. This design is preferable if the protective valve is designed to equip the valves of the main oil and product pipelines that do not experience significant thermal loads.

The elastic stiffening element 14 may take the form of a pair of counter-oriented disk springs, each of which is fixed relative to one of the rods 8 and 9, as shown in FIG. 2.

In cases where the safety valves are designed to equip the valves in the cooling systems of nuclear reactors and piping piping of TPP boilers, it is preferable to use bellows or membranes as means 12 and 13 for axial movement of the rods 8 and 9 and sealing the compensation chambers 2 and 3 (see, respectively, the figures 3 and 4).

The described valve operates as follows.

In the initial position (see figures 1, 3 and 4), the pressure in the cavity of the open valve P ₃ and in both of its bypass pipes P ₁ and P _{2 is the} same, and both shutters are usually closed. After the valve is closed, the pressure in that branch pipe, which functioned as a pressure head, remains at the initial working level Р _slave , and the pressure in that branch pipe, which functioned as a drain, drops to almost zero. It does not matter in which direction the flow of the working medium passed through the valve until it is closed.

In other words, if P ₁ = P _slave , then P ₂ → 0, and vice versa, if P ₂ = P _slave , then P ₁ → 0.

As the heating medium in the cavity of the closed valve, the pressure P ₃ rises up to a predetermined critical value. As a result, one of the axial displacement means 12 (or 13) moves the corresponding rod 8 with the spool 10 (or the rod 9 with the spool 11) from its seat, compressing the elastic stiffener 14 and effectively pressing the spool from the drain pipe side to its seat. This ensures that part of the working medium is discharged from the valve cavity into the corresponding compensation chamber 2 or 3 and into the pressure line.

Industrial applicability

The proposed safety valve is suitable for mass production using available materials and components and standard metalworking equipment.

Claims (3)

1. Automatic direct-acting safety valve, having: a hollow axisymmetric body with two mirror-symmetric compensation chambers hydraulically separated from one another; lateral fittings, which are designed to connect these cameras to the bypass pipes of the protected valve on different sides of its locking element; end fittings, which are designed to connect these cameras to the cavity of the valve being protected and are equipped with saddles at the joints with these cameras; coaxial rods, which are located inside the specified housing with a gap between their adjacent ends, have spools at opposite ends corresponding to the indicated saddles, and together with the saddles serve as the first and second valves, respectively; and means for axial movement of said rods for locking both gates with an open valve and unlocking one of them when critical pressure is reached in the cavity of a closed valve, characterized in that an elastic stiffener is inserted between the means of axial movement of these rods. 2. The automatic safety valve according to claim 1, characterized in that the elastic stiffening element is made in the form of a spiral spring segment covering the gap zone between adjacent ends of the rods. 3. The automatic safety valve according to claim 1, characterized in that the elastic stiffening element is made in the form of a pair of counter-oriented disk springs, each of which is fixed relative to one of the rods.

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