SE408328B - SAFETY VALVE DEVICE - Google Patents

Description

¿{711ovc-s sliding of a limit pressure overcomes the spring force and through its movement opens for pressure medium supply to a second piston, which through its movement provides a rapid evaluation of the control line. When large lcz-offs are set on the safety, for example at safety valves in nuclear power plants, it is usual to require an annual adjustment of the spring shaft in such a multi-stage valve, which necessitates disassembly of the valve. Assembly and disassembly is time-consuming and requires a relatively large effort of personnel.

The above-mentioned inconveniences are significantly reduced in a safety device according to the invention. The characteristics of a safety valve device according to the invention appear from the appended patent claims.

The invention will be described in the following with reference to the accompanying schematic; drawings, in which Fig. 1 shows a self-service valve device according to a first embodiment of the invention with a self-controlled main valve, which is designed according to the pressure relief principle, and Fig. 2 a second embodiment of the invention where the main valve is made according to the pressure loading principle. Fig. 5 shows the same device as on. Fig. 1 but in a more detailed manner.

In Fig. 1, a main inlet line coming from the reactor pressure tank in a nuclear reactor is shown, and 2 a self-medium controlled main valve, the inlet portion 3 of which is connected to the inlet line 1, while the outlet 4 is connected to a blow-off line 5, which in turn leads to a low pressure system.

The main valve 2 has a free-running cone. in order from below a seat 6, a constriction 7, a cone piston 8 and a guide piston 9. The cone piston has a larger diameter than the seat, but the guide piston smaller. The two pistons 8 and _9 are provided with piston rings and run in separate guide cylinders 10 and 11, respectively. A throttled connection 12 is located between the space 13 on. the upper side of the cone piston 8 and the valve housing in general. The fluid _15 is connected via openings 14 in the cylinder 11 to a control medium connection 15 'connected to a control line 15.

When the main valve is closed, the reactor pressure acts shut-off. the upper sides of the net and the pistons and opening on the underside of the cone piston 8 '.

When valve 2 is to be opened, the steam is evacuated. the upper side of the pistons by connecting the control line 15 to the blow-off line 5 via. a relief line 16-. Because the forces. on. the upper sides of the pistons 8 and 9 disappear and the force on the cone piston is greater than the force on. the top of the net, the cone is pressed up, and the main valve opens .. ao. The connection between the control line 15 and the relief line 16 is established either by means of an electrically controlled control valve 17 or by a bursting plate in an explosive plate 18 or 18 'bursting. The control valve 17 contains a feed coil 19 which is connected to the output side of an amplifier 20, the input side of which is connected to a comparator 21, where a reference value set by means of a reference value device 22 is compared with the output signal from an electric pressure sensor 25, via. a pipe 24 is connected to the inlet portion 5 of the main valve 2. The control valve 17 can also be operated manually or remotely operated by supplying the solenoid coil 19 with an operating pulse independent of the pressure sensor 25. The bursting plates 18 and 18 'are connected in series with each shut-off valve 25 and 25, respectively. '25', which. are open. when the main valve 2 is closed. One of the shut-off valves 25 teh 25 'is closed when the valve valve 2 is to be closed after a blow has been triggered by the bursting of an explosive plate into the explosive plate 18 or 18'. When the connection between the control line 15 and the relief line 16 is terminated, after a blow has been taken, etc., steam comes. one via the throttle 12 and the openings 14 is supplied with space on the flank side of the pistons.

The net force on the cone piston 8 becomes downward again and the valve 2 closes.

Extra. stàZ-ngnirngslcraft is obtained by one on. the drawing does not show the spring which is placed on, B top of the boiler piston So. as soon as the pressure in the main steam line 1 exceeds a limit value set by the reference device 22, the control valve 17 opens. This limit value constitutes a maximum of 95 73 and at least 60 s »of The task is only to constitute a reserve for the control valve 17. Often sufficient safety is achieved with only one connection in parallel with the control valve 17, which means, for example, that the components. 18 'and 25' and those directly connected thereto; the pipe sections can then be dispensed with. It is also possible to provide a device according to the invention by connecting in parallel. the control valve 17 with a connection which contains a group of bursting plates interconnected in parallel and a shut-off valve connected in series with the group. Opening the control valve 17 means the steps of reducing the pressure on the blasting plates 18 and 18 ', even if the high-pressure system's pressure cooker should continue, so the blasting plates always remain intact as long as the control valve 17 and associated control devices and connecting lines remain faultless. .

Instead of using the control system shown in Fig. 5, connected to the coil 19, the coil 19 can be connected to a current source via. a pressure medium-controlled switch, the control inlet of which is connected to the main steam line 1.

As an additional alternative to that on. In the arrangement shown, the valve 17 can be made with pneumatic or hydraulic control, the components.

Claims (1)

1 10 1. 2711076-5 1 2 4 19, 20, 21, 22, 23 in a manner known per se replaced with corresponding pneumatic or hydraulic components. The device shown in Fig. 2 contains the same components as that in Fig. 1, but in such a way that the conical piston 8 is relieved of pressure on the upper and lower side when the main valve is closed. If the control valve 17 is opened or the burst plate 18 ruptures, the underside of the cone piston 8 is thereby pressurized, and the main valve opens. Stymedium axis closure is on. Fig. 2 denotes! with 15 ". In a safety valve device according to the invention it is justified to allow longer intervals between vsräe revision than in a device which instead of blasting plates contains a corresponding number of multi-stage valves. Vfidsre are blasting plate units simple and light, which is advantageous when mounting and disassembly, and units with new blasting plates can be provided without significant cost overload, which will be immediately replaced by the old blasting assemblies in the event of a revision. which is either designed in such a manner known per se that the valve (2 ') can be opened by connecting a control media outlet (15 ") of the valve (2') to said high-pressure system (1), or in such a manner for in such a way that the valve (2) can be opened by connecting a control medium connection (15 ') of the valve (2) to said low-pressure system (S), wherein the control media connection (15 'or 15 ") is connected to one of said systems via a plurality of parallel, pressure-sensitive shut-off devices, while at least one of said shut-off devices is constituted by a control valve (electrically or by means of a special pressure means operable). 17), which is arranged open when the pressure in said high-pressure system (1) exceeds a certain limit pressure, characterized a. D by the fact that the (other) blocking device (s) contain a (each) explosive tinplate (18, 183) connected in series with an open shut-off valve (25, 25 '), while the limit pressure - is not more than 95 7! - of the pressure at which an explosive plate breaks in at least one explosive plate (18, 18'). - LEAD PUBLICATIONS: