Pulse safety device

Like their less sophisticated related devices, safety valves , ISPs are used to protect against mechanical destruction of vessels and pipelines by excessive pressure , by automatically discharging liquid , vapor and gaseous media from systems and vessels when pressure is exceeded. But to ensure high flow rates of the medium in emergency mode, sometimes dozens of direct-acting safety valves have to be installed due to their insufficient throughput . Under these conditions, it is advisable to use ISPs , they are successfully used to protect systems and assemblies with high operating parameters if it is necessary to dump large quantities of the working environment. Since the auxiliary energy is used for control in the control unit, the magnitude of the control efforts can be very large, since it is no longer limited by the size of the valve. This force can be effectively used both for precise triggering and for ensuring reliable tight closure of the locking element.

IPA are significantly more expensive than direct-acting valves, but with an increase in medium parameters, the difference in their cost quickly decreases ^[1] .

Consider the principle of operation of an ISP using the example of a block diagram of a device used on equipment with very high environmental parameters (in this case, steam ).

The main safety valve in the operating position is closed by a vapor medium. When the valve is closed, the pressure in the chamber "A" under the piston (3) is equal to the pressure in the chamber "B" above the piston in view of the throttle (1). In the steam discharge pipe under the spool (2), the pressure of the device for receiving the discharge medium is set. The spool (2) is pressed against the seat due to the pressure difference in these devices above and below the spool (2).

When the control pulse valve 1 or 2, or the pulse electromagnetic valve, is opened, the steam from chamber "B" via the discharge line is triggered in the receiving device and pressure is set in chamber "B", but since the piston area (3) is larger than the spool area (2) , the resultant force proportional to the pressure difference between the protected and receiving devices and the difference in the area of ​​the piston (3) and the spool (2) directed upward will act on the valve’s working body. Thus, the working body moves up, the valve opens.

The control impulse valves 1 and 2 are closed in operation under the action of the spring (4) and the additional pressing force created by the electromagnet (5). Impulse valves 1 and 2 consist of a full bore safety valve with a spring (4) and a control element made in one housing. When the set pressure is exceeded, the sensor is triggered and the electromagnets are turned off. In this case, an additional force is removed, pressing the cone (6) of the valve, and the valve remains pressed against the seat under the action of the spring (4). With a further increase in pressure, the cone (6) rises up and allows steam to enter the chamber "C" under the shut-off plate (7) of the control element. The shut-off plate (7) rises with the spool (9) of the control element and opens the discharge line (10) of the main valve. The main valve opens.

The pulse solenoid valve is equipped with an electromagnet that acts only on the valve opening (a spring acts on the closing), i.e. it can be remotely opened. During normal operation, it is closed, the closed position is ensured by the action of the spring and the pressure of the medium of the protected device. When the pressure increases more than the set one, the sensor is activated and power is supplied to the opening electromagnet, it opens and the main valve opens.

When the pressure in the protected device is less than required, the sensor is activated, the power is removed from the electromagnetic valve, it closes and the main valve closes. In pulse safety valves 1 and 2, when the pressure in the protected device decreases below the required value, the valve (6) sits in the seat under the action of the spring (4), the pressure in the chamber "C" drops and the shut-off plate (7) with the spool (9) returns to the original position, blocking the discharge line (10).

In this IPA, the pulse safety valves 1 and 2, as well as the pulse electromagnetic valve, duplicate each other, as it were, “insure” each other, they are tuned to different operating pressures and use different operating principles, different pressure measurement channels to exclude the possibility of failure for any reason safety valve.

Moreover, on extremely important equipment, for example, on the equipment of the primary circuit of nuclear power plants , there are often several such devices, for example, three or two control ones, one main. This is done for the spatial separation of safety devices and their additional duplication ^{[1] [3]} .

One of the varieties of pulse safety devices are valves, in which all the necessary load on the spool of the main valve is created by extraneous energy, for example, high-pressure compressed air . The air from the high-pressure system supplied to the piston of the main valve through the pilot device creates the necessary force to close the valve and provide the required degree of tightness. When the set pressure is reached in the system, the air is automatically reset using the pilot device and the valve opens ^[1] .