Subsea device for providing a pressurized fluid

Abstract

 The present invention relates to a subsea device (10) configured to provide a pressurized fluid for a fluid activated consumer (42). The subsea device (10) comprises a pump body (12) comprising an opening (18), a fluid accumulator (16) in fluid communication with the opening, and a piston (19) arranged within the opening (18) and movable back (29) and forth (30) in a longitudinal direction of the opening (18). The subsea device (10) comprises furthermore a solenoid (20) coupled to the piston (19) and configured to move the piston (19) in at least one of the back (29) and forth (30) directions.

Description

[0001] The present invention relates to a subsea device configured to provide a pressurized fluid for a fluid activated subsea consumer, especially to a subsea device which may be operated and arranged in a subsea environment.

[0002] In subsea applications, for example subsea oil production, hydraulic power is frequently used to operate actuators and other moving parts. A major obstacle in deep water is the extreme high pressure experienced by the equipment at these depths. Therefore, hydraulic power is typically supplied through pipelines in an umbilical from a top side facility. Providing the hydraulic power from the top side facility may increase cost and may decrease reliability due to the transmission via pipelines. However, in many subsea applications a continuous fluid volume requirement of the hydraulic consumers is limited. For example, opening or closing a valve in certain circumstances may require only a very low constant flow.

[0003] Therefore, it is an object of the present invention to provide hydraulic power for subsea applications with high reliability at low cost.

Summary of the invention

[0004] According to the present invention, this object is achieved by a subsea device configured to provide a pressurized fluid for a fluid activated consumer as defined in claim 1, a subsea system as defined in claim 8, and a subsea station as defined in claim 9. The dependent claims define preferred and advantageous embodiments of the present invention.

[0005] According to an embodiment, a subsea device is provided. The subsea device is configured to provide a pressurized fluid for a fluid activated consumer in a subsea environment. The subsea device comprises a pump body having an opening, for example a cylindrical opening, and a fluid accumulator for storing pressurized fluid. The fluid may comprise for example hydraulic oil. The fluid accumulator is in fluid communication with the opening of the pump body, for example via a hydraulic line. A piston is arranged within the opening and movable back and forth in a longitudinal direction of the opening. An outer peripheral surface of the piston may fit into an inner peripheral surface of the opening. Therefore a movement of the piston in at least one of the back and forth directions pressurizes a fluid arranged in the opening. The subsea device comprises furthermore a solenoid which is coupled to the piston such that the solenoid moves the piston in at least one of the back and forth directions upon an actuation of the solenoid. The solenoid may be actuated by electrical power supplied to the solenoid.

[0006] In subsea applications the fluid volume requirement of hydraulic consumers may be very limited and thus a very low fluid flow may be required only. An average low fluid flow can be provided by the piston powered by the solenoid. The fluid accumulator provides a standby source of hydraulic power for a short-term increased fluid flow and for maintaining a constant fluid flow. Therefore, simple components and a few reliable moving parts may provide a sufficient hydraulic power source for subsea applications. The components are robust and may be arranged in harsh subsea environments such that cost intensive pipelines for providing hydraulic power from a top side facility can be avoided.

[0007] According to another embodiment, the subsea device comprises a level indicator which is arranged at the fluid accumulator. The level indicator provides a level signal indicating a charging level of the fluid accumulator. Furthermore, the subsea device may comprise a control circuit, for example an electronic control, which is coupled to the level indicator of the fluid accumulator and to the solenoid. The control circuit may control the solenoid in response to the level signal received from the level indicator. The level signal may indicate when the fluid accumulator is completely charged with pressurized fluid. Therefore, the control circuit may actuate the solenoid to charge the fluid accumulator until the level indicator signals that the fluid accumulator is completely charged. Thus, a reliable stand-by source of hydraulic power may be provided.

[0008] According to another embodiment, the subsea device comprises a check valve arranged between the opening and the fluid accumulator. The check valve may be arranged for example in a hydraulic line with a flow direction of the check valve from the opening to the fluid accumulator. Therefore, the check valve allows a fluid flow from the opening to the fluid accumulator and prohibits a fluid flow from the fluid accumulator to the opening. A further check valve may be arranged in a further hydraulic line coupling the opening to a hydraulic fluid reservoir. The further check valve is arranged such that it allows a fluid flow from the hydraulic fluid reservoir to the opening and prohibits a fluid flow from the opening to the hydraulic fluid reservoir. By using the solenoid operated piston in a matching cylindrical opening connected to the two check valves, a low constant flow of a hydraulic fluid can be established with a simple control of the solenoid only.

[0009] The subsea device may comprise furthermore a housing for accommodating at least the pump body, the fluid accumulator, the piston and the fluid to be pressurized. The fluid to be pressurized surrounds at least partially some or all of the above-listed components. In other words, the components of the subsea device may be contained within one fluid-filled compartment and the fluid may be used as the hydraulic medium. Thus, a special fluid reservoir and a volume compensation may be omitted.

[0010] According to another embodiment of the present invention, a subsea system configured to provide a pressurized fluid for a fluid activated consumer in a subsea environment is provided. The subsea system comprises at least two subsea devices as defined above. Each subsea device comprises a corresponding output, at which the pressurized fluid is provided. The subsea system comprises furthermore a valve arrangement which is coupled to the outputs of the subsea devices in parallel. By connecting a plurality of subsea devices in parallel by means of for example check valves or solenoid valves, an increased volume flow may be provided or a reliability may be increased.

[0011] According to another embodiment, a subsea station is provided which comprises a fluid activated consumer arranged subsea and the subsea device defined above. The subsea device is coupled to the fluid activated consumer, for example a hydraulically operated equipment, and supplies the pressurized fluid to the fluid activated consumer. The subsea device is arranged subsea, in particular near to the fluid activated consumer. Therefore, short hydraulic lines are required only for providing hydraulic power to the fluid activated consumer. Thus, robustness and reliability may be increased.

[0012] Although specific features described in the above summary and in the following detailed description are described in connection with specific embodiments and aspects of the present invention, it should be understood that the features of the exemplary embodiments and aspects may be combined with each other unless specifically noted otherwise.

Brief description of the drawings

[0013] The present invention will now be described in more detail with reference to the accompanying drawings.

Fig. 1 shows schematically a subsea device according to an embodiment of the present invention for providing a pressurized fluid in a subsea environment.

Fig. 2 shows schematically a subsea station according to an embodiment of the present invention.

Detailed description of preferred embodiments

[0014] In the following, exemplary embodiments of the invention will be described in more detail. It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other unless specifically noted otherwise.

[0015] Fig. 1 shows schematically a subsea device 10 for providing a pressurized fluid in a subsea environment. The subsea device 10 comprises a housing 11 accommodating a pump body 12, a first check valve 13, a second check valve 14, a hydraulic line 15, a fluid accumulator 16, a control circuit 17 and an output 33. The subsea device 10 may comprise more components which are not shown in Fig. 1 for clarity reasons, for example a back flow hydraulic line, an electrical power supply line, an electrical control line and so on. The pump body 12 comprises an opening 18, for example a cylindrical bore, in which from one side a first end of a piston 19 is inserted. The piston 19 is arranged within the cylindrical opening 18 such that it is movable back and forth in a longitudinal direction of the cylindrical opening, i.e., to the left and to the right in Fig. 1 as shown by arrows 29 and 30, respectively. The other side of the opening 18 is connected to the hydraulic line 15, in which the check valves 13 and 14 are arranged and which couples the opening 18 to the fluid accumulator 16 and to the output 33. At a second end of the piston 19, which is not arranged within the cylindrical opening 18, a solenoid 20 is arranged which is coupled to the control circuit 17. When the solenoid 20 is powered by the control circuit 17, it may move the piston 19 in the back or in the forth directions 29 and 30, i.e., it may move the piston 19 to the left or to the right in Fig. 1. For example, the piston 19 may be biased by a spring (not shown) into the left direction 29 and may be forced by a magnetic force from the solenoid 20 into the right direction 30. Thus, by energizing and de-energizing the solenoid 20, the piston 19 is moved selectively to the left or to the right. As an alternative, the second end of the piston 19 surrounded by the solenoid 20 may comprise a permanent magnet. By controlling a polarity of a magnetic field induced by the solenoid 20, the piston 19 may be forced into the left direction 29 or into the right direction 30 without the need of a spring. The outer surface of the piston 19 and the inner surface of the cylindrical opening 18 may be sealed against each other such that a fluid in the hollow space of the opening 18 is not allowed to flow along the surface of the piston 19 in the left direction 29.

[0016] The hydraulic line 15 couples the second check valve 14 to a reservoir 21. The reservoir 21 supplies a large amount of fluid, for example hydraulic oil. The reservoir 21 may be arranged inside the housing 11, or may be arranged outside the housing 11, or the housing 11 itself may represent the reservoir such that all components within the housing 11 are surrounded by the fluid or hydraulic oil. The second check valve 14 is arranged such that it allows a fluid flow from the reservoir 21 to the opening 18, but inhibits a back flow from the opening 18 to the reservoir 21. The hydraulic line 15 couples furthermore the opening 18 to the fluid accumulator 16 via the first check valve 13. The first check valve 13 is arranged such that it allows a fluid flow from the opening 18 to the fluid accumulator 16, but inhibits a back flow from the fluid accumulator to the opening 18. The hydraulic line 15 provides furthermore a fluid communication from the fluid accumulator 16 to the output 33.

[0017] The fluid accumulator may comprise an opening, for example a cylindrical opening or a cylindrical bore, in which a piston 22 is arranged. The piston 22 is biased with a spring 23. When the cylindrical bore is filled with fluid, the piston 22 is urged by the fluid against the bias force provided by the spring 23. A bar 24 arranged at the piston 22 may be used in combination with a level indicator or sensor 25 to determine the current position of the piston 22 within the cylindrical bore. A corresponding level signal indicating a charging level of the fluid accumulator 16 may be transmitted from the sensor 25 to the control circuit 17 via an electrical line as shown in Fig. 1.

[0018] At the output 33 of the subsea device 10 a further hydraulic line 26 may be provided for transmitting pressurized fluid from the subsea device 10 to a subsea consumer, which may be activated by the pressurized fluid. The subsea consumer may comprise for example a hydraulic activated valve or a hydraulic activated motor. For controlling a flow of the pressurized fluid in the hydraulic line 26, a control valve 27 may be provided. The control valve 27 may comprise a solenoid operated valve controlled by a further control unit 28.

[0019] Operation of the subsea device 10 will be described now in more detail. A fluid to be pressurized is provided in the reservoir 21. The fluid may comprise for example hydraulic oil. The piston 19 is operated by the control circuit 17 and the solenoid 20 to move back and forth in directions 29 and 30. When the piston 19 is moved in direction 29, hydraulic fluid flows from the reservoir 21 through the check valve 14 into the opening 18. When the piston 19 is moved in the opposite direction 30, the fluid is pressurized and flows, due to the check valves 13 and 14, from the opening 18 through the check valve 13 in the direction of the fluid accumulator 16 and the output 33. In case the consumer connected at the hydraulic line 26 does not consume all the pressurized fluid provided, the excess is flowing into the fluid accumulator 16, thus charging the fluid accumulator 16. While the fluid accumulator 16 is charged, the piston 22 is moved against the force of the spring 23 in direction 31. When the consumer requires more hydraulic fluid than currently provided from the pumping piston 19 or when the piston 19 is moving in direction 29, piston 22 of the fluid accumulator 16 is moved by the spring 23 into direction 32, thus providing the required fluid flow. A current charging state of the fluid accumulator 16 is monitored or sensed with the level indicator 25. When the fluid accumulator 16 is charged completely or up to a predefined level, the control circuit 17 stops actuating the piston 19 and the consumer receives pressurized fluid from the fluid accumulator 16. Thus, a constant flow of pressurized fluid can be provided to the consumer.

[0020] Fig. 2 shows a subsea station 40 comprising a system 41 for providing a pressurized fluid to a fluid activated consumer 42. The system 41 comprises three pump subsea devices (PD1, PD2 and PD3) 43-45 and a valve arrangement 46. The subsea station 40 is arranged subsea, i.e., the subsea station 40 may be arranged in a depth of several hundred to several thousand meters, for example in a depth of 3000 meters below sea surface 47. The subsea station 40 may be for example a part of a subsea oil production or a subsea energy transmission. Each of the pump subsea devices 43-45 may comprise for example a subsea device 10 as described above in connection with Fig. 1. The outputs 33 of the pump subsea devices 43-45 are coupled to the valve arrangement 46 such that the pump subsea devices 43-45 are arranged in parallel. An output of the valve arrangement 46 is coupled to the consumer 42. The multiple pump subsea devices 43-45 connected in parallel by means of for example check valves or solenoid valves may provide an increased volume flow of the pressurized fluid to the consumer 42. Furthermore, a reliability of the system 41 may be increased. If the sum of the fluid streams provided by the pump subsea devices 43-45 is larger than required by the subsea consumer 42, even in case of a failure of one or more of the pump subsea devices 43-45 a sufficient hydraulic power may be provided to the subsea consumer 42.

Claims

1. A subsea device configured to provide a pressurized fluid for a fluid activated consumer, the subsea device (10) comprising:

- a pump body (12) comprising an opening (18),

- a fluid accumulator (16) for storing pressurized fluid, which is in fluid communication with the opening (18),

- a piston (19) arranged within the opening (18) and movable back (29) and forth (30) in a longitudinal direction of the opening (18), and

- a solenoid (20) coupled to the piston (19) and configured to move the piston (19) in at least one of the back (29) and forth (30) directions, wherein a movement of the piston (19) in at least one of the back (29) and forth (30) directions pressurizes the fluid in the opening (18).

2. The subsea device according to claim 1, further comprising:

- a level indicator (25) at the fluid accumulator (16), the level indicator (25) providing a level signal indicating a charging level of the fluid accumulator (16).

3. The subsea device according to claim 2, further comprising:

- a control circuit (17) coupled to the level indicator (25) of the fluid accumulator (16) and to the solenoid (20), the control circuit (17) being configured to control the solenoid (20) in response to the level signal received from the level indicator (25).

4. The subsea device according to claim 2 or 3, wherein the fluid accumulator (16) comprises a spring pressurized piston (22) arranged within an opening of the fluid accumulator (16), wherein the level signal of the level indicator (25) indicates a position of the spring pressurized piston (22) within the opening of the fluid accumulator (16).

5. The subsea device according to any one of the preceding claims, further comprising:

- a check valve (13) arranged in the fluid communication between the opening (18) of the pump body (12) and the fluid accumulator (16) such that the check valve (13) allows a fluid flow from the opening (18) to the fluid accumulator (16) and prohibits a fluid flow from the fluid accumulator (16) to the opening (18).

6. The subsea device according to any one of the preceding claims, further comprising:

- a further check valve (14) arranged in a further fluid communication coupling the opening (18) to a hydraulic fluid reservoir (21), the further check valve being arranged such that the further check valve (14) allows a fluid flow from the hydraulic fluid reservoir (21) to the opening (18) and prohibits a fluid flow from the opening (18) to the hydraulic fluid reservoir (21).

7. The subsea device according to any one of the preceding claims, further comprising:

- a housing (11) accommodating at least the pump body (12), the fluid accumulator (16), the piston (19) and the fluid to be pressurized, wherein the fluid to be pressurized at least partially surrounds at least one of the pump body (12), the fluid accumulator (16) and the piston (19).

8. A subsea system configured to provide a pressurized fluid for a fluid activated consumer in a subsea environment, the subsea system (41) comprising:

- at least two subsea devices (10; 43-45) according to any one of the preceding claims, wherein each subsea device of the at least two subsea devices provides pressurized fluid at a corresponding output (33) of the subsea device (10), and

- a valve arrangement (46) coupling to the outputs (33) of the at least two subsea devices in parallel.

9. A subsea station, comprising:

- a fluid activated consumer (42) arranged subsea, and

- a subsea device (10; 43-45) according to any one of claims 1-7, wherein the subsea device (10; 43-45) is coupled to the fluid activated consumer (42) for supplying the pressurized fluid to the fluid activated consumer (42), wherein the subsea device (10; 43-45) is arranged subsea.

Drawing