RU2756951C2 - Double-closure valve - Google Patents

Abstract

FIELD: engineering elements.

SUBSTANCE: invention relates to pipeline fittings operating as part of power units characterized by difficult operating conditions, high reliability requirements and maximum restrictions on weight and size characteristics, for example, as part of nuclear power units for transport purposes, as a localising closure element on secondary steam pipelines. The double-closure valve comprises a body with an axial and a lateral branch pipes and two sealing seats, a main and an additional closure elements connected with coaxially aligned inner and outer stems sealed by a stuffing box and controlled by independent drives. The main closure member is equipped with an unloading mechanism comprised of an inner sealing seat guide, a sealing band on the inner stem, a support nut and an elastic element, wherein grooves are made on the inner surface of the main closure member, a passage is made through the support nut and the main closure member in the area of the sealing seat, and there is a cavity between the inner surface of the main closure member and the outer surface of the additional closure member providing passage of the medium into the lateral branch pipe.

EFFECT: technical result is increased reliability of the valve in emergency situations.

4 cl, 3 dwg

Description

The invention relates to pipeline valves operating as part of power plants characterized by difficult operating conditions, high reliability requirements and maximum restrictions on weight and size characteristics, for example, as part of nuclear power plants for transport purposes, as a localizing shut-off element on secondary steam pipelines.

In the body of the pipeline fittings, two sealing seats are coaxially placed, with each seat interacting with two shut-off sealing bodies, which are controlled through the telescopically located inner and outer rods by a combined drive.

A characteristic feature of the operation of the valves under consideration is the need for emergency closure when a potentially hazardous medium of the primary circuit system enters the second circuit in the event of an inter-circuit leakage.

To ensure this, the drive of one of the gates is made remotely controlled by means of a fast-acting drive, for example, a pneumatic drive. The specified shutter (hereinafter referred to as the main shutter) automatically closes on a signal from the control system. When the emergency depressurization of the primary circuit system is confirmed in relation to the secondary circuit system, the shutter (hereinafter referred to as the additional shutter) is closed by means of a manual drive.

If the emergency depressurization of the primary circuit system is not confirmed with respect to the secondary circuit system, the main gate should be open to let steam through to the turbine.

After the emergency closing of the main gate, the pressure of the working medium in the cut-off section of the second circuit increases and additional effort from the pneumatic drive is required to open the main gate.

To reduce the required opening force of the main gate, its design is made with a unloading mechanism.

Known two-stop angle valve with a combined drive according to the inventor's certificate SU No. 1635663, F16K 31/17, dated 11/17/87, in which two shut-off bodies are made in the form of one-piece cylindrical parts connected to rods having a stuffing box seal.

Such a design does not exclude the action of the working medium on the stuffing box assembly, which reduces the degree of tightness of the inner cavity relative to the external environment, thereby reducing the reliability of the valve. The opening of the shut-off elements of the valve occurs at full pressure drop of the medium, which leads to an increase in the working forces on the rods and also to a decrease in its reliability.

Also known is a valve with two closures No. 1137818, F16K 11/20 dated 06/17/85, the valve consists of two locking elements: the main one connected to the inner stem by means of a detachable connection, and an additional one connected to the outer stem using a flexible element, for example, bellows. The design of the valve provides self-alignment of the shut-off elements relative to the sealing seats of the body, which increases the degree of tightness of the valves.

The disadvantages of this valve include the fact that, in the "closed" position, the stuffing box seals of the inner and outer rods are directly influenced by the parameters of the working medium, especially when the pressure of the medium in the shut-off section of the installation is increased and for opening the main valve at an increased pressure of the working medium acting on him, an additional force is required to its stem, which entails a joint decrease in the reliability of the valve.

The closest in terms of design and most of the proposed features is a two-stop valve according to application No. 2016119296/06, containing a body with axial and lateral branch pipes and two sealing seats, interacting with the latter, the main and additional locking bodies with spools located in the inner cavity of the axial branch pipe of the body and connected to coaxially located inner and outer (tubular) rods and their independent drives, while the spool of the main locking body is connected to the outer (tubular) rod.

The disadvantage of the specified two-stop valve is that the main locking body is connected to the outer (tubular) rod, controlled by a fast-acting actuator, and when triggered to close the gland, sealing the connection of the inner rod to the outer, is exposed to the working environment, including a potentially dangerous , and if the emergency situation is not confirmed, it will require additional effort from the actuator to open it to overcome the increased pressure drop of the working medium.

Finding the stuffing box under the influence of high parameters of the medium leads to a loss of tightness of the internal cavity in relation to, which reduces the reliability of the valve.

The operation of the valve with an increased force on the stem when the main shut-off element is opened with an increased pressure drop of the medium on it, also leads to a decrease in its reliability.

The technical objective of the present invention is to create a two-stop valve, which excludes the influence of the working environment in the cut-off section of the installation on the tightness of the stuffing box seal between the inner and outer rods with respect to the external environment and reduces the working force required to open the main shut-off element.

The technical result of solving this problem is to increase the reliability of the two-stop valve.

The specified technical result is achieved due to the fact that in a two-stop valve containing a body with axial and lateral nozzles and two sealing seats, interacting with the latter, the main and additional locks connected to coaxially located inner and outer rods, sealed with a gland and controlled independent drives, the main lock is connected to the inner rod and is equipped with an unloading mechanism, consisting of an internal sealing seat of the lock, a sealing band on the inner rod, a support nut and an elastic element, moreover, grooves are made on the inner surface of the main lock, in the support nut and in the main gate in the area of the sealing the saddle has through holes, and between the inner surface of the main lock and the outer surface of the additional lock there is a cavity that allows the medium to pass into the side pipe.

The inner stem has a head with a guide collar made in the form of a torus.

A cylindrical stop is made on the head of the inner rod, located inside the elastic element and interacting with the end face of the support nut.

The elastic element is made in the form of a package of Belleville springs.

Increased reliability is achieved due to the operation of the valve with two shut-off bodies with reduced working forces by installing in the main shut-off body, an unloading mechanism fixed on the inner rod and consisting of an inner sealing seat of the gate, a sealing band on the head, an inner rod, a support nut, an elastic element and elements that ensure the passage of the working medium from the axial branch pipe to the lateral branch pipe through the cavity between the main and additional shut-off bodies.

The proposed on / off valve is shown in the drawings:

- in figure 1 - the "open" position - for the additional shut-off element and the "closed" position for the main shutter;

- figure 2 - “closed” position - for the main shut-off element, with the position of the unloading mechanism - “open”, “open” position - for an additional shutter;

- in figure 3 - "open" position - for the main shut-off element, with the position of the unloading mechanism "closed", the position of the additional shutter - "open".

The two-stop valve contains a body 1 with inlet and outlet nozzles, the main 2 and additional 3 shut-off elements connected to the coaxially located inner 4 and outer 5 rods, controlled by independent drives.

The body 1 has two sealing seats 6 and 7, located on the side of the axial branch pipe, opposite to the gland assembly 8 and the outlet of the inner 4 and outer 5 rods from the body 1.

The main shut-off body 2 has an external sealing collar 9, which interacts when closing with the sealing seat 7 of the housing 1. An additional shut-off body 3 is located in the inner cavity of the main shutter 2.

An unloading mechanism is located in the inner cavity of the main shut-off body 2, consisting of a sealing seat 10, a sealing collar 11 on the head 12 of the inner rod 4, a support nut 13, an adjusting gasket 14 and an elastic element 15, made, for example, in the form of a disk spring pack.

The sealing collar 11 is made on the end face of the head 12 of the inner rod 4, the outer surface of which has a guide collar 16 made in the form of a torus.

The support nut 13 is attached to the main shut-off element 2 by means of a threaded connection and has holes 17 for the passage of the working medium.

On the inner surface of the main closure member 2, grooves 18 are made, and grooves 19 are made on the outer cylindrical surface of the head 12, which also provide the passage of the working medium.

The main shut-off body 2 in the area of the sealing seat 10 is equipped with a through hole 20. Between the inner surface of the main shut-off body 2 and the outer surface of the additional shut-off body 3, a cavity 21 is made for the passage of the working medium into the side pipe, the volume of which is selected based on the flow area in the assembly unloading mechanism seals.

The head 12 of the inner rod 4 has a stop 22 interacting with its end face with the inner end of the support nut 13.

The two-way valve works as follows.

During the operation of the installation, both shut-off elements 2 and 3 are in the "open" position, providing steam passage to the turbine.

In the event of an emergency closure of the main shut-off element 2 from the pneumatic actuator, the force is transmitted through the inner rod 4 to the main shutter 2, moving it all the way into the sealing seat 7 of the housing 1, overlapping the flow area of the valve (see Fig. 1).

When the main shut-off element 2 is closed, the pressure of the medium in the cut-off section of the second circuit increases significantly.

To put the cut-off section into operation, it will be necessary to open the main shut-off element 2. Due to the increased pressure of the working medium acting on the main shut-off element 2, additional effort is required for this.

When the inner rod 4 moves downward from the position of the main shut-off element 2 closed (see Fig. 2), the sealing collar 11 on the head 12 moves away from the sealing seat 10, forming a flow area for the working medium. The main shut-off element 2 at the initial moment remains in the closed position until the increased pressure in the inlet pipe is released (see Fig. 3).

After releasing the pressure of the medium and further movement of the inner rod 4, the head 12 acts with the end of the stop 22 on the inner end of the support nut 13, moving the main shut-off element 2 until it opens, ensuring the passage of the working medium through the main flow section 23 (see Fig. 3) in the lateral pipe branch. The package of Belleville springs 15 presses the main shut-off element 2 against the head 12 of the inner rod 4.

Thus, the arrangement of the main and additional shut-off elements in the axial pipe is opposite to the gland assembly and the supply of the main shut-off element, connected to the internal rod, with an unloading mechanism consisting of sealing elements and power parts, makes it possible to increase the reliability of the two-stop valve.

Claims (4)

1. A two-stop valve containing a body with axial and lateral nozzles and two sealing seats, interacting with the latter, the main and additional shut-off bodies connected to coaxially located inner and outer rods, sealed by a gland and controlled by independent drives, characterized in that the main shut-off body is connected with an internal rod and is equipped with an unloading mechanism consisting of an internal sealing saddle of the valve, a sealing band on the internal rod, a support nut and an elastic element, and grooves are made on the inner surface of the main shut-off body, in the support nut and in the main shut-off body in the area of the sealing seat through holes, and between the inner surface of the main shut-off body and the outer surface of the additional shut-off body there is a cavity that provides the passage of the medium into the side pipe. 2. A two-stop valve according to claim 1, characterized in that the inner stem has a head with a guide collar made in the form of a torus. 3. A two-stop valve according to claim 1 or 2, characterized in that a cylindrical stop is made on the head of the inner rod, located inside the elastic element and interacting with the end face of the support nut. 4. Two-stop valve according to claim 1, characterized in that the elastic element is made in the form of a package of Belleville springs.

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