SAFETY DEVICE FOR A LINEAR ACTUATED PROCESS VALVE

Description

[0001] The present invention relates to a safety device for a linearly actuated process valve and a system comprising the safety device. Background of the invention

[0002] In deep-sea oil and gas production facilities, process valves are used to regulate or shut off the flow rate of the extracted medium. These process valves are actuated by electrohydraulic actuators, such as a hydrostatic linear actuator. This actuator may contain a hydraulic cylinder with one or more springs that, in the event of a hydraulic actuator failure, move the piston of the hydraulic cylinder to a predetermined position. This ensures that the process valve is safely closed in case of a malfunction.

[0003] DE 10 2020 200 263 A1 discloses a hydrostatic linear actuator that exerts a tensile force on a safety-relevant component in an emergency, the tensile force initially being generated by a relaxing emergency spring. In the final part of the movement, a hydraulic accumulator is engaged via a displacement-dependent control system, the hydraulic fluid of which is pumped into a cylinder chamber that acts on a piston to which the component is coupled.

[0004] EP 2 989 360 A1 discloses a system comprising a remotely controlled vehicle, a spring pack housing, a vehicle adapter and a connecting adapter which can be detachably connected to the spring pack housing by means of a quick-coupling device.

[0005] US 2002 / 124889 A1 concerns a hydraulic underwater drive and method for a gate valve.

[0006] US patent 2016 / 245425 A1 discloses an actuator for a valve in an underwater installation.

[0007] WO 02 / 081932 A2 discloses a valve actuator with a safety mechanism. The actuator is hydraulically operated and closes a valve with spring assistance in the event of pressure loss (fail-closed).

[0008] US 4 651 970 A relates to a drive arrangement with an auxiliary energy storage device in the form of a coil spring.

[0009] A disadvantage of a linear actuator according to DE 10 2020 200 263 A1 is its increased weight due to the safety components integrated into the actuator (spring systems, additional hydraulic components). This makes it more difficult to replace a defective linear actuator at great depths using an underwater vehicle (Remotely Operated Vehicle - ROV). Disclosure of the invention

[0010] According to the invention, a safety device for a linearly actuated process valve and a system comprising the safety device are proposed, with the features of the independent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

[0011] The invention provides a compact and simple safety device for linearly actuated process valves as a separate module, possessing purely mechanical properties (i.e., it does not include an electrical, hydraulic, or pneumatic drive unit). The safety device can be arranged between a linear actuator and a process valve using standard mechanical interfaces.

[0012] The safety device for a linearly actuated process valve comprises a housing and a piston rod, which is linearly displaceable within the housing and connectable to the process valve. The piston rod of the safety device can be connected, for example, to a shut-off device of the process valve by means of a mechanical connection. This mechanical connection can be, for example, a connection made via a second mechanical interface, a screw connection, or a weld. Preferably, the process valve is a disc valve that uses a disc as a shut-off device.

[0013] Furthermore, the safety device includes a piston connected to the piston rod and at least one spring clamped between the piston and an end face of the housing. This means that the piston rod and piston are held in a predetermined position (end position) by the spring force as long as no external force greater than or opposite to the spring force acts on the piston rod. Preferably, a process valve connected to the safety device is in a safe position at this end position of the piston rod. A closed position of the process valve is particularly preferred as the safe position.

[0014] Furthermore, the safety device comprises a first mechanical interface by means of which the safety device can be detachably connected to a linear actuator. Preferably, the first and / or second mechanical interface can include a quick-release fastener, in particular a rotary fastener (i.e., a connection that can be closed by rotating one of the components involved, preferably by a maximum of 360°, 180°, 90°, or 45°), e.g., a bayonet fastener or a quick-release fastener according to EN ISO 13628-8, "Linear (push) interface", type A or type C. This quick-release fastener has a flange with recesses on one side, arranged around a first shaft. Claw-shaped projections of a second shaft on the opposite side can be axially inserted into the recesses of the flange, and the two sides of the quick-release fastener can be connected to each other by rotating the second shaft 45° clockwise.By rotating the second shaft 45° clockwise, its claw-shaped projections lie axially and radially against the flange of the first shaft, thus creating a positive locking connection between the two sides of the quick-release fastener.

[0015] The safety device can have one side of the quick-release fastener described above, and a linear actuator to which the safety device can be connected can have the other side of the quick-release fastener.

[0016] The first mechanical interface allows a linear actuator connected to the safety device to be replaced with an ROV without having to remove or open the safety device. This significantly simplifies the maintenance and installation of linear actuators, especially at great depths.

[0017] The safety device offers a very simple and compact fail-safe mechanism based on proven springs and requires no electric, pneumatic, or hydraulic drive. The spring force of at least one spring in the safety device automatically moves the process valve to a predefined position (e.g., open or closed) when the actuating force is lost (e.g., due to a drive failure, power outage, deactivation, or removal of the actuator). The modular design of the components, which separates the safety device from a linear actuator, simplifies the design of new systems or allows for the retrofitting of existing ones.

[0018] According to a preferred embodiment, the safety device comprises a pre-tensioning means configured to pre-tension the at least one spring of the safety device independently of any movement of the piston rod. This allows the piston rod to be actuated with less force to open the process valve, since the spring force does not need to be overcome. Consequently, a linear actuator connectable to the safety device for actuating the process valve can be made smaller.

[0019] The preloading device preferably has a shaft that acts on the piston and exerts a force on the spring. This represents a simple and compact means of providing the preload force.

[0020] The shaft can preferably extend outwards through the housing to allow for external actuation. This eliminates the need for a power generation device, such as a hydraulic drive, within the safety device.

[0021] The shaft preferably has a third mechanical interface for detachable connection with an external drive, for example with a hydraulic drive of the linear actuator that can be connected to the safety device.

[0022] Preferably, the housing of the safety device is filled with a pressurized fluid. This pressurized fluid preferably serves to withstand external pressure acting on the safety device, as well as to protect against corrosion and to lubricate the components of the safety device. The pressurized fluid can, for example, be hydraulic oil.

[0023] According to the invention, the safety device comprises a pressure compensation device configured to equalize the pressure between the environment and the interior of the safety device. Preferably, the pressure compensation device is a diaphragm accumulator or a bladder accumulator having a fluid connection to a housing opening. A bladder accumulator is particularly preferred. The bladder accumulator can be designed with a flexible wall that encloses a predefinable bladder storage volume and can move axially and radially in response to the pressure prevailing inside the accumulator. The flexible wall of the bladder accumulator can, for example, be made of an elastomer and be designed to be fluid-tight and resistant to contact with seawater under high pressure.

[0024] The pressure compensation device is particularly advantageous when using the safety device in underwater applications.

[0025] Preferably, the pressure compensation device is configured to set a pressure inside the safety device within a range between ambient pressure and 10 bar above ambient pressure. This can be achieved, for example, by means of a spring that pre-tensions a diaphragm attached to the pressure compensation device. The pre-tension force of the spring allows the pressure inside the pressure compensation device to be set to a desired value above ambient pressure.

[0026] According to the invention, the pressure compensation device is arranged in the piston rod. This results in a particularly space-saving arrangement of the pressure compensation device within the interior of the safety device. The pressure compensation device is preferably connected to the environment outside the housing (e.g., seawater) via a bore in the piston rod.

[0027] Preferably, the safety device further comprises a second mechanical interface by means of which it can be connected to the process valve. This allows the safety device to be disconnected and replaced on the process valve, as well as several safety devices to be connected in series to increase the force required to close the process valve.

[0028] Preferably, the safety device further comprises at least one sensor designed to detect the position of the piston and / or the piston rod.

[0029] Preferably, the safety device includes a display device configured to show the position of the piston and / or piston rod on the outside of the housing. The display device may include a physical indicator (e.g., a movable arrow) that shows the position of the piston and / or piston rod on the outside of the housing. The physical indicator may be mechanically connected to the piston and / or piston rod. The display device may be used by an ROV and / or monitored by a camera.

[0030] The system according to the invention for actuating a process valve comprises at least one linear actuator and one or more safety devices as described above. One or more of the safety devices is connected to the linear actuator via the first (and optionally second) mechanical interface.

[0031] Preferably, the system includes several safety devices connected in series to increase the spring force for closing the process valve.

[0032] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0033] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0034] The invention is schematically illustrated with reference to exemplary embodiments in the drawings and is described in detail below with reference to the drawings. Character description

[0035] Figures 1a and 1bshow a first preferred embodiment of a safety device not according to the invention, each in a spatial external view and in longitudinal section; Figure 2 shows a second preferred embodiment of the safety device according to the invention in longitudinal section; Figures 3a and 3b show a schematic representation of the second and a third preferred embodiment of the safety device, each in relaxed and pre-tensioned state in longitudinal section; Figure 4 shows a hydraulic circuit diagram of a linear actuator according to a preferred embodiment of the system according to the invention; Figure 5 shows an example of a mechanical interface between a linear actuator and a safety device according to a preferred embodiment of the system according to the invention in longitudinal section; and Figure 6Figure 1 shows a linear actuator and a safety device according to a preferred embodiment of the system according to the invention in a spatial external view.

[0036] The figures contain identical elements with the same reference symbols. Therefore, repetitive descriptions are omitted where necessary. Detailed description of the drawing

[0037] Figures 1a and 1b show a first preferred embodiment of a non-inventive

[0038] Safety device 10. Figure 1a This shows it in a spatial exterior view and Figure 1b It shows a longitudinal section. The illustrated safety device 10 comprises a housing 1, on the first end face 1a of which a mechanical interface 2 is attached. The interface 2 is subsequently described in connection with Figure 5 more precisely described.

[0039] The housing 1 is filled with a hydraulic fluid, such as hydraulic oil. A piston rod 3 is axially displaceable within a bushing 5 in the housing 1. The piston rod 3 is shown here as a hollow example and advantageously includes openings for the hydraulic fluid to pass through (not shown). The bushing 5 also has openings for the hydraulic fluid to pass through (not shown). The piston rod 3 is connected to a piston 4.

[0040] Inside the housing 1, a spring 6 is arranged, which surrounds the piston rod 3 and is clamped between the piston 4 and a second end face 1b of the housing 1. Ends 3a, 3b of the piston rod 3 each pass through the end faces 1a, 1b of the housing.

[0041] In Figure 1bThe safety device 10 is shown in a state in which the end 3a of the piston rod 3 is not subjected to an external force. Consequently, the spring 6 presses the piston 4 against the end face 1a of the housing 1, thereby bringing the piston rod 3 with the piston 4 into a predetermined position (end position). When the end 3b of the piston rod 3 is connected to a process valve, this end position brings the latter into a safe position. Preferably, this is the closed position of the process valve.

[0042] Figure 2 A second preferred embodiment of the safety device according to the invention is shown in longitudinal section. In addition to the features shown in Figure 1bThe elements of the first embodiment of the safety valve described in the invention comprise a pressure compensation device 7, which is particularly suitable for use of the safety device in underwater applications. Figure 2The pressure compensation device 7 shown is arranged inside the piston rod 3 and is designed as a bladder accumulator 7. Positioning the bladder accumulator 7 within the piston rod 3 results in a particularly space-saving arrangement of the pressure compensation device 7. The bladder accumulator 7 is connected to the environment, e.g., seawater, via a bore 3c in the piston rod 3. The bladder accumulator 7 can be designed with a flexible wall that encloses a predefinable bladder storage volume and can move axially and radially in response to the pressure prevailing inside the piston rod 3. The flexible wall of the bladder accumulator 7 can, for example, be made of an elastomer and be designed to be fluid-tight and resistant to contact with seawater under high pressure. At normal pressure, i.e., as long as the safety device is above water, the accumulator is advantageously empty and has the smallest possible volume.When submerged below the water's surface, it fills with water as the external pressure increases and expands accordingly, leading to a pressure equalization between internal and external pressure.

[0043] Figures 3a and 3b Figure 1 shows a schematic representation of the second and a third preferred embodiment of the safety device 10 in longitudinal section.

[0044] Figure 3a Figure 1 schematically shows the position of the components of the safety device 10 according to the second preferred embodiment with the spring 6 relaxed (above the dashed center line) and with the spring 6 pre-tensioned (below the dotted center line). If the end 3a of the piston rod 3 is not subjected to an external force, the spring 6 is in a relaxed state (shown above the dashed center line) and pushes the piston rod 3 into its end position via the piston 4.

[0045] If, however, the end 3a of the piston rod 3 is subjected to an external force, it shifts in a direction opposite to the force acting on the spring 6 and, together with the piston 4, compresses the spring 6, thus pre-tensioning it (shown below the dashed center line). In such a position of the piston rod 3, a process valve connected to the piston rod 3 at its end 3b is in an operating position, preferably in an open position.

[0046] Figure 3bFigure 1 schematically shows the position of the components of the safety device 10 according to a third preferred embodiment with the spring 6 relaxed (above the dashed center line) and with the spring 6 pre-tensioned (below the dotted center line). In the third embodiment of the safety device 10 according to the invention, the piston is unidirectionally connected to the piston rod 3 via a driver 3d. Furthermore, the pre-tensioning of the spring 6 is independent of the movement of the piston rod 3 via a separate axis 4a, which, when force is applied, displaces the piston in a direction opposite to the force acting on the spring 6, thus pre-tensioning the spring 6 (shown below the dotted center line). Consequently, the process valve can be opened with less force on the piston rod 3 during normal operation, since the spring force does not need to be overcome.This is clearly illustrated by the positions of the outer end 3a of the piston rod 3 and the driver 3d, which are shown as solid lines in the piston rod's end position and as dashed lines when force is applied to the piston rod 3. It can be seen that the driver 3d does not come into contact with the piston 4 during normal operation. When external force is applied to the piston rod 3 and the axis 4a, the spring 6 expands and pushes the piston 4 towards the end face 1a of the housing 1. In doing so, the piston 4 comes to rest against the driver 3d and thus moves the piston rod 3 into its end position, in which a process valve connected to the end 3b of the piston rod 3 is in a secure position (shown above the dashed center line).

[0047] Figure 4Figure 1 shows a hydraulic circuit diagram of a linear actuator according to a preferred embodiment of the system according to the invention. The illustrated system comprises a linear actuator 20 and a safety device 10, which is connected to the linear actuator 20 by means of a first mechanical interface 2a. For this purpose, the first mechanical interface 2a of the safety device 10 is coupled to a corresponding interface 22 of the linear actuator 20. For coupling, the linear actuator 20 is, for example, attached to the safety device with interlocking interfaces 22 and 2a and rotated by 45°. On one side opposite the first interface 2a (i.e., at end 3b) of the safety device 10, a second interface 2b is arranged on the safety device 10, by means of which it can be connected to a process valve 30.

[0048] The process valve 30 shown includes a disc 31 which opens and closes a valve channel 34 as a result of a movement of the piston rod 3 of the safety device 10.

[0049] The in Figure 4 The linear actuator 20 shown contains a pump 27 that delivers hydraulic fluid from an interior T of the linear actuator 20 via a line 25 into a working chamber 21aa of a hydraulic cylinder 21. The hydraulic cylinder 21 shown is designed as a synchronous cylinder and comprises a piston rod 23 to which a piston 24 is attached. The piston 24 separates the working chamber 21aa from a second cylinder chamber 21ab, which is hydraulically connected to the interior of the linear actuator 20. The linear actuator 20 also includes a relief valve 28, which is likewise connected to the working chamber 21aa of the hydraulic cylinder 21 via the line 25. Figure 4This shows the position of the hydraulic cylinder 21 with the relief valve 28 open, in which the working chamber 21aa has a minimum size, while the opposite cylinder chamber 21ab has a maximum size.

[0050] A check valve 26 is arranged in line 25 between pump 27 and a port 29 of the pressure relief valve 28. This check valve prevents backflow of the hydraulic fluid into pump 27 when the working chamber 21aa is emptied. Additionally, a variable throttle 28aa is located upstream of the pressure relief valve 28, which allows the amount of hydraulic fluid flowing from the working chamber 21aa to be controlled / regulated.

[0051] When the relief valve 28 is opened, the spring force of the spring 6 of the safety device 10 acts on its piston 4 and displaces – via the piston rod 3 of the safety device 10 and the interface 2a, 22 between the safety device 10 and the linear actuator 20 – the piston rod 23 with the piston 24, until the working chamber 21aa has reached its minimum volume. In this, in Figure 4 In the depicted state, the piston rod 3 with the piston 4 of the safety device 10 is in the predetermined position (end position) and the valve channel 34 of the process valve 30 is closed by the disc 31. Advantageously, the relief valve 28 is a normally open (NO) valve that opens when the control voltage is released.

[0052] If, however, the relief valve 28 is closed and hydraulic fluid is pumped from the pump 27 into the working chamber 21aa, the force of the hydraulic cylinder 21 acts against the spring force of the spring 6 of the safety device 10, so that the spring 6 is pre-tensioned / compressed. The piston rods 23, 3 of the linear actuator 20 and the safety device 10 move in the opposite direction to the spring force and displace the associated disk 31 of the process valve 30 such that the valve channel 34 is opened (not shown).

[0053] Figure 5 Shows an example of a mechanical interface between a linear actuator and a safety device according to a preferred embodiment of the system according to the invention in longitudinal section. On the right side of Figure 5Figure 1 shows a section of the safety device 10, depicting parts of the piston rod 3, the piston 4, and the spring 6, as well as the end face 1a of the housing 1 facing the linear actuator 20, with the first mechanical interface 2a. The interface 2a is designed as a quick-release fastener (“Linear (push) interface”, type A or type C) according to EN ISO 13628-8. It comprises a first shaft 2aa around which a flange 2ab with recesses (not shown) is arranged. The linear actuator 20 is coupled to this interface 2a by means of the interface 22, which is the counterpart of the quick-release fastener. The one on the left side of Figure 5The depicted section of the linear actuator 20 shows, next to the interface 22, a part of the hydraulic cylinder 21 facing the safety device 10, including the piston rod 23. The interface 22 of the linear actuator 20 comprises a second shaft 22aa with claw-shaped projections 22ab in the manner of an inner flange, which engage the flange 2ab of the safety device 10. To connect the linear actuator 20 to the safety device 10, the claw-shaped projections 22ab are inserted axially into the recesses (not shown) of the flange 2ab and engaged with the flange 2ab by rotating the linear actuator 20 45° clockwise. Thus, in the Figure 5In the closed state of the quick-release fastener 2a, 22 shown, the claw-shaped projections 22ab engage axially and radially with the flange 2ab of the first shaft, thus creating a positive-locking connection between the two sides of the quick-release fastener 2a, 22. Due to this connection via the quick-release fastener 2a, 22, the opposite ends of the piston rods 23, 3 of the linear actuator 20 and the safety device 10 are frictionally connected to each other.

[0054] The quick-release fastener 2a, 22 makes it possible, in particular, to replace the linear actuator 20 with an ROV without having to remove or open the safety device. This significantly simplifies the maintenance and installation of the linear actuator, especially at great depths.

[0055] Figure 6Figure 1 shows a linear actuator and a locking device according to a preferred embodiment of the system according to the invention in a spatial external view. In this figure, the linear actuator 20 and the locking device 10 are shown connected by means of the quick-release fastener 2a, 22, as in Figure 2. Figure 5 shown, connected. Standardized handles 202, 204, 205 for mounting / dismounting the linear actuator 20 using an ROV are attached to the outside of the linear actuator 20.

[0056] In addition, a cable guide 201 is located on the front side of the linear actuator 20, which leads to a plug connection 203, to which the power supply for an electronic control unit 40, the electric drive unit 41 and the valves 28, 28a is connected.

[0057] Furthermore, a display device 206 (schematically shown) is arranged on the front face of the linear actuator, which indicates the position of the piston 24, 4 and / or the piston rod 23, 3 of the linear actuator 20 and the safety device 10. According to Figure 6 The indicator device is in position U ("unlocked"), i.e., the system consisting of linear actuator 20 and safety device 10 is in a normal operating state in which the working chamber 21aa of the hydraulic cylinder 21 is pressurized and occupies its maximum volume, so that neither the piston 24 of the hydraulic cylinder nor the piston 4 is at their end stops (cf. Figure 4 ).

[0058] Handle 202 allows the ROV to disconnect the electrical wiring of the linear actuator 20 at connector 203. This interrupts the power supply to pump 27 and relief valve 28, causing the relief valve 28 to open and the pressure in the working chamber 21aa of hydraulic cylinder 21 to drop. Consequently, the pistons 4, 24 of safety device 10 and linear actuator 20 are pushed into their respective end stops by the spring force of spring 6 (see figure). Figure 4 ) and the display device switches to position L ("locked").

[0059] The ROV can then be attached using the handle 204 and the quick-release fastener 2a, 22 (see below). Figure 5 ) Separate the linear actuator 20 from the locking device 10 by rotating it 45° counterclockwise. The handle 205 can then be used to transport the linear actuator 20.

[0060] The invention provides a compact and simple safety device for linearly actuated process valves as a separate module with purely mechanical properties. The safety device offers a very simple and compact fail-safe mechanism based on proven springs and requires no electrical, pneumatic, or hydraulic drive. The spring force of the at least one spring in the safety device automatically moves the process valve to a predefined position (e.g., open or closed) when the actuating force is lost (e.g., due to a drive failure, power outage, deactivation, or removal of the actuator). The modular design of the components, which separates the safety device from a linear actuator, can be used to simplify the design of new systems or to retrofit existing ones.

Claims

1. Safety device (10) for a linearly activated process valve (30), comprising a housing (1); a piston rod (3) which is mounted so as to be linearly displaceable in the housing (1) and is connectable to the process valve; a piston (4) which is connected to the piston rod (3); at least one spring (6) which is clamped between the piston (4) and an end face (1b) of the housing (1), a first mechanical interface (2, 2a) by means of which the safety device (10) is releasably connectable to a linear actuator (20), characterized in that the safety device comprises a pressure compensation device (7) which is specified to effect pressure equalization between an environment and an interior of the safety device (10), wherein the pressure compensation device (7) is disposed in the piston rod (3).

2. Safety device (10) according to Claim 1, having a pre-loading means which is specified to pre-load the at least one spring (6) independently of a movement of the piston rod (3).

3. Safety device (10) according to one of the preceding claims, wherein the housing (1) is filled with a pressurized liquid.

4. Safety device (10) according to one of the preceding claims, wherein the pressure compensation device (7) is specified to set a pressure in the interior of the safety device (10) in a range between ambient pressure and 10 bar above ambient pressure.

5. Safety device (10) according to one of the preceding claims, furthermore comprising a second mechanical interface (2b) by means of which the safety device (10) is connectable to the process valve (30) or to a further safety device (10).

6. Safety device (10) according to one of the preceding claims, furthermore comprising at least one sensor which is specified to detect the position of the piston (4) and / or of the piston rod (3), and a display device which is specified to indicate the position of the piston (4) and / or piston rod (3) on an exterior of the housing (1).

7. System for linearly activating a process valve (30), comprising at least one linear actuator (20); and one or a plurality of safety devices (10) according to one of the preceding claims, wherein the one safety device, or one of the plurality of safety devices (10), is connected to the linear actuator (20) by means of the first mechanical interface (2, 2a).

8. System according to Claim 7, comprising a plurality of safety devices (10) which are connected in series.