A VALVE ACTUATOR SYSTEM FOR CONTROLLING OF VALVES

Abstract: A valve actuator system for use above or under water, wherein at least one gas generator (1, 2) is provided for controlling the system. The gas generator (s) can be actuated by remote control, by use of electric cables or hydro acoustically without the use of cables, and locking mechanisms may be provided in order to lock the actuators in open and/or closed position. The locking mechanisms may be actuated by the gas generator(s). Each gas generator is equipped with its own safety system, in that the charge itself is protected by means of a piston (26), thermal insulation (32) and a burst disc (31). The valve actuator is protected against excessive pressure in that a safety shear disc (13, 14) is connected with a dead volume (10). Two-way control of actuators is achiev ed by using a bisected piston system.

Description: A Valve Actuator System for Controlling of Valves. The present invention relates to a valve actuator system for controlling or actuation of valves, above or under water. It is known to control valves hydraulically, pneumatically and mechanically. Such control is used for instance by offshore hydrocarbon production. A disadvantage of the control is that all the necessary energy for the movement of the shut-off members of the valves must be supplied partly over long distances, from a fixed or floating installation. Another disadvantage, in particular of hydraulic systems, is that these systems are very complicated and expensive, and in connection with emergency shut-off valves which are rarely used the hydraulic systems also are little economical, with much maintenance work without daily use of the systems. In accordance with the present invention it has been found that gas generators can be used to operate valve actuators for emergency shut-off valves and other suitable valves. Here, gas generator means a generator which by combustion of gunpowder inside of the generator develops a gas, which because of its pressure is able to shift a movable member in the valve actuator, such as a piston. Such gas generators may be fired by use of electric current. This may take place by use of a hydro acoustic system for control of accumulators for supply of current, and coded pulses through the water may be used. Thereby, the firing may take place without any direct connection between the gas generators and the place where the control is carried out, and uniquely coded pulses may be used for different operations and different gas generators, so that a completely selective remote control is achieved without any other connection than the water itself. In accordance with the invention it has been achieved a gas generator device for control or actuation of valve actuators, whereby each actuator is associated to at least one gas generator, for movement of the piston of the actuator (valve actuator) by means of the gas generator or generators. The firing of the gas generators may, as an alternative to electric firing, be carried out by mechanical detonators, chemical systems or by means of laser technique through optical fibre cables. The invention will in the following be explained closer, with reference to the accompanying drawings. Figs. 1, 2, 3 and 4 show principles and the functioning of the valve actuator. Fig. 1 shows a valve actuator based on the use of gas generators which generate gunpowder gas. In Fig. 1 are only shown gas generators 1, 2 for the closing and opening function. It will be understood implicitly that there may be several gas generators for repeated opening and closing functions. The broken lines show the valve in a closed position. The actuator is equipped with two pistons, a main piston 3 and a sub piston 4. The sub piston runs freely on the piston rod 5. Fig. 2 shows the geometry of the sub piston seen from above. The ribs 6 form a cavity 7 between the sub piston 4 and the main piston 3. The piston rod 5 is connected to the valve itself (not shown) . The purpose of two pistons will be explained below. Behind the two pistons in the cylinder chamber 8 of the actuator has been filled a liquid which will control the movement of the actuator during the closing function. By actuation the liquid is discharged out to the atmosphere through a shear disc 9 or to a separate tank (not shown) by under water use. The shear disc 9 may also be replaced by a usual check valve. Further, the actuator is provided with a dead volume 10 for protection against excessive pressure. The dead volume is connected to the passages 11, 12 from the gas generators 1, 2 through safety shear discs 13, 14. When the valve actuator is used under water it may be necessary to vent the residual pressure in the cylinder of the actuator when used several times or once. In Fig. 1 this has been shown in that an expansion tank 15 has been associated with the cylinder chamber 8 of the actuator through a labyrinth passage 16. In Fig. 4 is shown an alternative where the venting takes place by means of a tube 17 to the surface through the same labyrinth passage. The purpose of the labyrinth passage is to prevent that any substantial pressure is lost during the operation. The gas generators 1, 2 have been screwed directly into the cylinder wall 18 of the actuator. The gas generators may also be connected with the cylinder wall 18 of the actuator through tubes. This alternative has not been shown. The gas generators 1, 2 have been shown detailed in Fig. 3. The functioning of the gas generators is explained in the following. The purpose of the system described below is to protect each gas generator against the others when several gas generators have been assembled in a system. It is necessary to protect the powder charge 19 against pressure and temperature. The housing 20 having a passage 21 for the electric cords (not shown) and an igniter device 22 is connected to the discharge portion 23 through the connecting part 25. A valve 26 is also provided here, having a valve seat 27 in the coupling part 24. The valve 26 is mounted in the system by means of a second coupling part 28 having a pre-tensioning nut 29. The valve stem 30 is connected to the coupling part 28 through a burst disc 31. Behind the valve seat 27 is provided thermal insulation 32. During the assembly the pre-tension nut 29 is tightened, so that the valve 26 is fastened to the valve seat 27. This will make a safe barrier against influence of pressure on the powder charge 19. The thermal insulation 32 protects against the influence of the temperature. By actuation of the powder charge a current is supplied to resistance cords 22 which ignite the powder charge 19. The built up pressure causes that the valve 26 moves backwardly and bursts the disc 31. The gas will flow out into the passages 25 through the filters 33, to the cylinder chamber 8 of the valve actuator through a check valve 34, 35. The system comprising a valve 26 and a burst disc 31 has been chosen in order to avoid that parts of traditional burst discs shall be able to destroy piston surfaces in the actuator and clog passages etc. By actuation of a gas generator 1, 2 as explained above the locking mechanism 36 will open and the main piston 3 and the sub piston 4 of the actuator will move to the position shown with broken lines in Figs. 1 and 4. If it is desired to lock the actuator in the closed position a locking mechanism 37 as shown in Fig. 1 and 4 can be used. The pressure in the liquid behind the pistons will cause that the shear disc 9 bursts and the liquid will then flow out as explained earlier and will control the valve actuator movement hydraulically. If the pistons 3, 4 in the valve actuator from some reason are not able to be moved the pressure ahead of the main piston will build up, so that the safety shear disc 13, 14 will be ruptured and the liquid is conducted into the dead volume 10. Thus, this is a safety function in the system. By multi- operations each gas generator will have its own passage to the dead volume, so that several attempts of operating the actuator may be made. By opening (reversing) of the actuator the gas generator 2 will be actuated and the gas will flow in between the main piston 3 and the sub piston 4 in the broken line position. The locking mechanism 37 will open up and the main piston 3 will move towards open position. The opening velocity is less critical than the closing velocity for pure emergency shut- off valves. Therefore the opening velocity is controlled by the combustion time of the gas generator. The purpose of using a two-piston solution is that it would be adverse to conduct the hot gas into a cavity filled with liquid. By multi-operations new liquid must be pumped in behind the sub piston 4, so that it will move up towards the main piston 3 as shown in closed position in Figs. 1 and 4.

Claims: CLAI MS . 1. A valve actuator system for control of valves provided above or under water, characterized in that gas generators (1, 2) which are used for operation of the valve actuator is shielded against the influence of pressure and temperature by means of an isolated piston (26) which is fastened by means of a tightening device (29) and a burst disc (31). 2. A valve actuator system as specified in claim 1, characterized in that a dead volume (10) which protects the system against excessive pressure is provided. 3. A valve actuator system as specified in claim 1 or 2, characterized in that the residual pressure after operation of the gas generator when used several times or once under water is vented by conducting gas to an expansion tank (15). 4. A valve actuator system as specified in claim 1 or 2, characterized in that the residual pressure after operation of the gas generator when used several times or once under water is vented by conducting gas through a pipe (17) which leads to the surface. 5. A valve actuator system as specified in claim 1 to 4, characterized in that a sub piston (4) forming a cavity (7) between the sub piston (4) and the main piston (3) is provided in the valve actuator. 6. A valve actuator system as specified in claim 5, characterized in that said cavity (7) is used to carry gas of high pressure from the gas generators (1, 2) for reversing of the valve actuator.

Inventors: NARUM HENNING, NARUM, HENNING
Applicants: RAUFOSS AMMUNISJONSFABRIKKER, A/S RAUFOSS AMMUNISJONSFABRIKKER
Application year: 1986
Main classification: F16K17
IPC codes: E21B33, F15B15, F16K31