Subsea closed loop cooling system

Abstract

The invention relates to a closed loop subsea cooling system with subsea coolers. A coolant pump assembly (2) is located in a dedicated sealed, gas-filled coolant pump housing (8a) in coolant fluid connection with at least one subsea cooler (4a, 4b, 4c). Heat sinks (3a, 3b, 3c) in a dedicated sealed, gas-filled electronics housing (8b, 8c, 8d) are in coolant fluid connection with the subsea coolers (4a, 4b, 4c). An accumulator is in coolant fluid connection with the subsea coolers (4a, 4b, 4c), whereby the electric coolant pump (2) is adapted to pump coolant through at least one subsea cooler (4a, 4b, 4c), at least one heat sink (3a, 3b, 3c) and back to at least one electric coolant pump assembly (2), thereby forming a closed loop subsea cooling circuit.

Description

Technical Field

[0001] This invention relates to a closed-loop cooling system for the seabed. Background Technology

[0002] Traditional shell-and-tube heat exchangers do not allow cooling of electronic components / equipment, but only of fluids. Using seawater as a cooling medium carries the risk of scaling and clogging, making it unsuitable for cooling electronic components or for use in narrow conduits. Summary of the Invention

[0003] This invention provides a closed-loop subsea cooling system for cooling electronic devices using glycol / water-based fluids under low pressure (without compensation from surrounding seawater). The system typically includes a top-side centrifugal pump housed within an atmospheric sampling tank, a natural convection cooler, an accumulator, distribution piping, and heat sinks for cooling electrical and electronic circuitry. The closed-loop system allows for the use of a wide range of fluids, while operating pressure remains unaffected by water depth. Furthermore, the closed-loop system eliminates internal structural and contamination issues, while maintaining antifreeze and corrosion inhibitors within the system. Positioning the coolant pump within an atmospheric-pressure tank enables the top-side coolant pump to be used in protected environments.

[0004] The cooling system is modular, and a single coolant pump can distribute coolant to multiple radiators and multiple coolers. Radiators and coolers can be arranged in series and / or parallel to optimize various system aspects, such as coolant pump differential pressure and flow rate, cooler size, operating pressure, etc.

[0005] This invention relates to a subsea cooling system having a closed-loop cooling circuit. The closed-loop subsea cooling system includes at least one subsea cooler, at least one electric coolant pump assembly in a dedicated sealed, gas-filled coolant pump housing, at least one radiator in a dedicated sealed, gas-filled electronic device housing in the closed-loop cooling circuit, and at least one coolant volume compensation unit in the closed-loop cooling circuit. The at least one electric coolant pump assembly is adapted to pump coolant at least through the at least one subsea cooler and the at least one radiator, and return it to the at least one electric coolant pump assembly.

[0006] At least one coolant volume compensation unit compensates for volume changes in the fluid circuit and fluid volume changes that are typically caused by temperature fluctuations. The circuit is closed, and compensation is not performed due to external pressure on the closed circuit.

[0007] The pressure in a closed-loop subsea cooling circuit can typically be below 1000 kPa. Due to flow resistance, there will be some pressure differentials throughout the cooling circuit. Additionally, there will be some less noticeable pressure differentials due to the hydrostatic pressure difference across the circuit.

[0008] The pressure in the coolant pump housing with a dedicated seal and filled gas and at least one electronic device housing with a dedicated seal and filled gas can typically be in the range between 50 kPa and 150 kPa.

[0009] At least one subsea cooler, at least one electric coolant pump assembly, and at least one radiator of the closed-loop subsea cooling circuit are located at substantially the same level and are rated to be less than 1000 kPa.

[0010] A closed-loop subsea cooling system may include multiple heat sinks, each housed within a dedicated, sealed, gas-filled electronic device housing. Each sealed electronic device housing may include several heat sinks connected in parallel or series.

[0011] A closed-loop subsea cooling system may include multiple subsea coolers.

[0012] A closed-loop subsea cooling system may include multiple subsea coolers, and the number of subsea coolers is only limited by the specific problem.

[0013] A closed-loop subsea cooling system may include multiple heat sinks connected in parallel, each located in a dedicated, sealed, gas-filled electronic device housing, and the number of heat sinks is limited only by the specific problem.

[0014] A closed-loop subsea cooling system may include multiple heat sinks connected in series, each located in a dedicated, sealed, gas-filled electronic device housing, and the number of heat sinks is limited only by the specific problem.

[0015] The pump assembly and at least one radiator may be top-side graded components.

[0016] At least one coolant volume compensation unit may be located outside the closed-loop cooling circuit.

[0017] At least one coolant volume compensation unit may be located inside at least one sealed housing within a sealed housing.

[0018] A closed-loop subsea cooling system may include several radiators in each tank and any combination of multiple radiators and tanks connected in parallel or in series, and the combinations suggested above are merely to illustrate different embodiments of the invention.

[0019] The pump in the pump assembly can be a centrifugal pump. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the seabed closed-loop cooling system according to the first embodiment of the present invention;

[0021] Figure 2This is a schematic diagram of the seabed closed-loop cooling system according to the second embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the seabed closed-loop cooling system according to the third embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the seabed closed-loop cooling system according to the fourth embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of the seabed closed-loop cooling system according to the fifth embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of the seabed closed-loop cooling system according to the sixth embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of the seabed closed-loop cooling system according to the seventh embodiment of the present invention;

[0027] Figure 8 This is a perspective view of a typical layout of the sixth embodiment of the present invention; and

[0028] Figure 9 This is a cross-section of a typical coolant pump assembly within the coolant pump housing. Detailed Implementation

[0029] Figure 1 The subsea closed-loop cooling system 1 of the present invention is shown in its simplest form. The closed-loop cooling system is isolated from the surrounding seawater pressure. The components of the system are located at approximately the same height to minimize the static pressure head within the system and reduce the overall pressure level.

[0030] Coolant pump assembly 2 requires a non-liquid environment and is typically a top-side centrifugal coolant pump housed within a sealed coolant pump housing 8a. Coolant pump assembly 2 and coolant pump housing 8a form a coolant pump unit. Housing 8a forms a dedicated pressure tank that protects the coolant pump assembly from ambient conditions. The stand-alone coolant pump / tank assembly is exposed to seawater and can be positioned independently of radiators and coolers. The stand-alone coolant pump assembly unit can be used for other applications such as chemical injection systems and liquid discharge.

[0031] The coolant pump assembly includes a coolant pump and an electric motor that drives the coolant pump. The hermetically sealed coolant pump housing 8a typically includes a tank, flange, and seals. An accumulator may be integrated with the hermetically sealed coolant pump housing 8a.

[0032] The outlet of the coolant pump assembly is connected via pipe 20a to the inlet of a first radiator 3a in the first sealed electronic device housing 8b, which cools the electronic device. The size of the radiator 3a is determined based on the pressure within the closed loop (typically less than 1000 kPa) and need not be designed to withstand the pressure of the surrounding seawater. Pipe 21a connects the outlet of the first radiator 3a to the inlet of a first subsea cooler 4a. Pipe 22 connects the outlet of the first subsea cooler 4a to the inlet of the coolant pump assembly 2. A coolant volume compensation unit in the form of an accumulator 5 is connected via a T-joint to pipe 22 between the first heat exchanger 4a and the coolant pump assembly 2 to allow for volume changes in the closed loop, typically due to temperature variations. Pipe 22 between the first heat exchanger 4a and the coolant pump assembly 2 also includes an isolation valve 7 between a vacuum valve 6a and a filling valve 6b. The isolation valve 7 closes when the closed loop is filled with coolant, typically a glycol and water-based fluid.

[0033] Figure 2 It shows the corresponding Figure 1 The system's closed-loop cooling system at the bottom of the sea. 1. In Figure 2 In addition to the first heat sink 3a in the first sealed electronic device housing 8b, the system also includes a second heat sink 3b in the second sealed electronic device housing 8c for cooling the electronic device. A conduit 25 connects the outlet of the first heat sink 3a to the inlet of the second heat sink 3b, and thus, the first heat sink 3a and the second heat sink 3b are connected in series.

[0034] Figure 3 It shows the corresponding Figure 2 The system's underwater closed-loop cooling system 1. However, in Figure 3 In this system, a second subsea cooler 4b is located between the first radiator 3a and the second radiator 3b along a pipe 25 between the radiators 3a and 3b.

[0035] Figure 4 It shows the corresponding Figure 2 The system's underwater closed-loop cooling system 1. However, in Figure 4 In this configuration, two radiators 3a and 3b are connected in parallel. The pipe 20a from the outlet of the coolant pump assembly 2 is divided in the inlet manifold 10, which forms a T-junction, into a first inlet pipe 20b leading to the inlet of the first radiator 3a and a second inlet pipe 20c leading to the inlet of the second radiator 3b. Therefore, the first radiator 3a and the second radiator 3b are connected in parallel.

[0036] The coolant flow from the outlet of the first radiator 3a flows into the first outlet pipe 21b, while the coolant flow from the outlet of the second radiator 3b flows into the second outlet pipe 21c. The two outlet flows join into pipe 21a in a T-junction and flow towards the subsea cooler 4a.

[0037] Figure 5 It shows the corresponding Figure 4 The system's underwater closed-loop cooling system 1. However, in Figure 5 In the process, the first subsea cooler 4a is connected to the outlet of the first radiator 3a, and the second subsea cooler 4b is connected to the outlet of the second radiator 3b. Then, the two outlet flows are joined to the pipe 21a in the outlet manifold 11, which is formed as a T-shaped joint, and flow to the subsea cooler 4a.

[0038] Figure 6 It shows the corresponding Figure 2 The system's closed-loop cooling system at the bottom of the sea. 1. In Figure 6 In this system, multiple heat sinks 3a connected in parallel within a first sealed electronic device housing 8b, and multiple heat sinks 3b connected in parallel within a second sealed electronic device housing 8c. Additionally, the accumulator 5 is integrated with a sealed coolant pump housing 8a filled with gas.

[0039] The accumulator 5 can be integrated with any one of the sealed housings 8a-8d.

[0040] Figure 7 This is a schematic diagram of a closed-loop cooling system 1 in a typical subsea configuration. A coolant pump assembly in a gas-filled, hermetically sealed coolant pump housing 8a pumps coolant to a modular compact pump (MCP) 9 for cooling by multiple radiators 3d, and then from the MCP 9 to an inlet manifold 10 that branches the coolant-containing pipe into three branches, each branch corresponding to each of three hermetically sealed electronic housings containing variable speed drive (VSD) units 8b, 8c, and 8d. The first hermetically sealed electronic housing 8b includes multiple first radiators 3a connected in parallel, the second hermetically sealed electronic housing 8c includes multiple second radiators 3b connected in parallel, and the third hermetically sealed electronic housing 8d includes multiple third radiators 3c connected in parallel.

[0041] Subsea coolers 4a, 4b, and 4c are connected in conduits between inlet manifold 10 and each of the three hermetically sealed electronic device housings 8b, 8c, and 8d. Outlet manifold 11 connects the outlet pipes from each of the three hermetically sealed electronic device housings 8b, 8c, and 8d to a conduit that returns to the pump assembly in the hermetically sealed coolant pump housing 8a. An accumulator 5 is provided to accommodate minor volume changes in the closed-loop system.

[0042] Figure 8 It shows Figure 6 The actual layout of the subsea closed-loop cooling system 1 is shown. Coils forming subsea coolers 4a, 4b, and 4c surround each of the three VSDs in the three hermetically sealed electronic device housings 8b, 8c, and 8d. The inlet manifold 10 is located below the MCP 9, and the outlet manifold 11 is located above the MCP 9. The coolant volume compensation unit is an accumulator 5 located outside the cooling loop, and therefore not inside any of the hermetically sealed housings.

[0043] Figure 9 This is a typical cross-section of a sealed coolant pump housing 8a with pump assembly 2, which includes an electric motor and a centrifugal pump. Pipe 20a provides an inlet to the coolant pump assembly. Pipe 22 provides an outlet to the coolant pump assembly 2. The sealed coolant pump housing 8a is formed as a sealed container having a bell-shaped portion 30 and a cover portion 31 that closes the bell-shaped portion 30. The internal volume of the sealed container is filled with gas, and is typically filled with an inert and stable gas to provide a dry and non-corrosive environment.

[0044] The cooling system is modular because a single coolant pump assembly can distribute coolant to multiple radiators and multiple coolers. Radiators and coolers can be arranged in series and / or parallel to optimize various system aspects such as coolant pump differential pressure and flow rate, cooler size, operating pressure, etc.

Claims

1. A closed loop subsea cooling system having a closed loop cooling circuit, comprising: at least one subsea cooler (4a, 4b, 4c) located in the closed loop cooling circuit; at least one electrically driven coolant pump assembly (2) located in a dedicated sealed, gas-filled coolant pump housing (8a) in the closed loop cooling circuit; at least one heat sink (3a, 3b, 3c) located in a dedicated sealed, gas-filled electronics housing (8b, 8c, 8d) in the closed loop cooling circuit; at least one coolant volume compensation unit located in the closed loop cooling circuit; whereby the at least one electrically driven coolant pump assembly (2) is adapted to pump coolant at least through the at least one subsea cooler (4a, 4b, 4c), the at least one heat sink (3a, 3b, 3c) and back to the at least one electrically driven coolant pump assembly (2), wherein the pressure in the dedicated sealed, gas-filled coolant pump housing (8a) and at least one dedicated sealed, gas-filled electronics housing (8b, 8c, 8d) is in the range between 50 kPa and 150 kPa.

2. The closed loop subsea cooling system according to claim 1, wherein the pressure in the closed loop subsea cooling system is less than 1000 kPa.

3. The closed loop subsea cooling system according to any one of claims 1 to 2, wherein the at least one subsea cooler (4a, 4b, 4c), the at least one electrically driven coolant pump assembly (2) and the at least one heat sink (3a, 3b, 3c) of the closed loop subsea cooling system are located substantially in one horizontal plane and are rated less than 1000 kPa.

4. The closed loop subsea cooling system according to any one of claims 1 to 2, comprising a plurality of heat sinks (3a, 3b, 3c), each located in a dedicated sealed, gas-filled electronics housing (8b, 8c, 8d).

5. The closed loop subsea cooling system according to any one of claims 1 to 2, comprising a plurality of subsea coolers (4a, 4b, 4c).

6. The closed loop subsea cooling system according to any one of claims 1 to 2, comprising a plurality of heat sinks (3a, 3b, 3c) connected in parallel, each located in a dedicated sealed, gas-filled electronics housing (8b, 8c, 8d).

7. The closed loop subsea cooling system according to any one of claims 1 to 2, comprising a plurality of heat sinks (3a, 3b, 3c) connected in series, each located in a dedicated sealed, gas-filled electronics housing (8b, 8c, 8d).

8. The closed loop subsea cooling system according to any one of claims 1 to 2, wherein the at least one electrically driven coolant pump assembly (2) and the at least one heat sink (3a, 3b, 3c) are top-side type fractional components.

9. The closed loop subsea cooling system according to any one of claims 1 to 2, wherein the pump of the at least one electrically driven coolant pump assembly (2) is a centrifugal pump.

10. The closed loop subsea cooling system according to any one of claims 1 to 2, wherein the at least one coolant volume compensation unit is externally located on the closed loop cooling circuit.

11. The closed loop subsea cooling system according to any one of claims 1 to 2, wherein the at least one coolant volume compensation unit is internally located within at least one of the dedicated sealed, gas-filled coolant pump housing (8a) and the dedicated sealed, gas-filled electronics housing (8b, 8c, 8d).

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