COOLING CIRCUIT FOR A SYSTEM FOR SUPPLYING AND COOLING A GAS

Abstract

A cooling circuit for a system for supplying and cooling a gas in a floating structure having a tank, the cooling circuit having a coolant flowing through it and including a main loop having: a compression device; a heat exchanger; an internal heat exchanger; and a turbocompressor, the cooling circuit includes a regulating branch connected to the main loop, the regulating branch having a valve that is configured to control the flow of coolant within the regulating branch, the main loop including a pressure sensor, the valve controlling the amount of coolant present in the main loop according to the pressure measured by the pressure sensor.

Claims

1-11. (canceled)

12. A cooling circuit for a system for supplying and cooling a gas of a gas of a floating structure comprising at least one tank configured to contain gas in the liquid state, a refrigerant fluid intended to lower the temperature of the gas in the liquid state contained in the tank flowing through the cooling circuit, the cooling circuit comprising a main loop comprising: at least one compression device providing the compression of the refrigerant fluid, at least one heat exchanger configured to make an exchange of heat between the refrigerant fluid and the gas contained in the tank, at least one internal heat exchanger comprising a first passage where the refrigerant fluid circulates at a first pressure and a second passage where the refrigerant fluid circulates at a second pressure lower than the first pressure, the first passage being arranged downstream of the compression device and upstream of the heat exchanger, the second passage being arranged downstream of the heat exchanger and upstream of the compression device, at least one turbo-compressor equipped with a compression member arranged between the compression device and the first passage of the internal heat exchanger and a turbine arranged between the first passage of the internal heat exchanger and the heat-exchanger, the compression member and the turbine being linked in rotation by a shaft, characterized in that the cooling circuit comprises a regulation branch connected to the main loop, said regulation branch comprising at least one valve configured for controlling the circulation of a refrigerant fluid within the regulation branch, the main loop comprising at least one pressure sensor, the valve controlling a quantity of refrigerant fluid present in the main loop depending on the pressure measured by the pressure sensor.

13. The cooling circuit according to claim 12, wherein the valve is configured to authorize the outlet of refrigerant fluid from the main loop via the regulation branch when the pressure measured by the pressure sensor is greater than a first pressure threshold.

14. The cooling circuit according to claim 13, wherein the valve is configured to authorize the inlet of refrigerant fluid into the main loop via the regulation branch when the pressure measured by the pressure sensor is less than a second pressure threshold, the second pressure threshold being lower than the first pressure threshold.

15. The cooling circuit according to claim 12, wherein the regulation branch is connected to the main loop downstream of the compression device and upstream of the compression member of the turbo-compressor, the pressure sensor being configured to measure the pressure within the main loop between the compression device and the compression member of the turbo-compressor.

16. The cooling circuit according to claim 12, wherein the regulation branch is connected to the main loop downstream of the second passage of the internal heat exchanger and upstream of the compression device, the pressure sensor being configured to measure the pressure within the main loop between the second passage of the internal heat exchanger and the compression device.

17. The cooling circuit according to claim 12, wherein the regulation branch is a first regulation branch connected to the main loop downstream of the compression device and upstream of the compression member of the turbo-compressor, the cooling circuit comprising a second regulation branch connected to the main loop downstream of the second passage of the internal heat exchanger and upstream of the compression device, the main loop comprising a two pressure sensors of which a first pressure sensor configured for measuring the pressure within the main loop between the compression device and the compression member of the turbo-compressor and a second pressure sensor configured to measure the pressure within the main loop between the second passage of the internal heat exchanger and the compression device.

18. The cooling circuit according to claim 17, wherein the first regulation branch controls an outlet of the refrigerant fluid out of the main loop and the second regulation branch controls the inlet of the refrigerant fluid into the main loop.

19. The cooling circuit according to claim 17, wherein the first regulation branch controls an inlet of the refrigerant fluid into the main loop and the second regulation branch controls the outlet of the refrigerant fluid out of the main loop.

20. The cooling circuit according to claim 12, comprising an additional exchanger, arranged between the compression member of the turbo-compressor and the first passage of the internal heat exchanger, the additional exchanger being configured for cooling the refrigerant fluid.

21. The cooling circuit according to claim 12, wherein the refrigerant fluid is nitrogen.

22. A system for supplying and cooling a gas of a floating structure comprising at least one tank configured for containing a gas in the liquid state, a supply circuit intended for gas to flow therethrough, the gas coming from the tank and configured for supplying gas to at least one gas consuming apparatus that equips the floating structure, characterized in that the system for supplying and cooling a gas comprises a cooling circuit according to claim 12.

Description

[0033] FIG. 1 represents a cooling circuit according to the invention comprising a regulation branch for a refrigerant fluid circulating in said cooling circuit,

[0034] FIG. 2 represents the cooling circuit according to the invention comprising two regulation branches,

[0035] FIG. 3 represents a first embodiment of a system for supplying and cooling a gas comprising a cooling circuit,

[0036] FIG. 4 represents a second embodiment of a system for supplying and cooling a gas comprising a cooling.

[0037] FIG. 1 represents a cooling circuit 4 which can be integrated into a system for supplying and cooling a gas of a floating structure transporting and/or storing gas in the liquid state and comprising a tank containing said gas, the tank not being shown herein.

[0038] The cooling circuit 4 comprises a main loop 22 within which a refrigerant fluid e.g. nitrogen circulates. The main loop 22 comprises a compression device 10, a turbo-compressor 13, an internal heat exchanger 18, a heat exchanger 17 and an additional exchanger 38. The purpose of the cooling circuit 4 is to circulate the refrigerant fluid within the main loop 22 so that the refrigerant fluid passes through the heat exchanger 17 at low temperature. Gas in the liquid state also flows through the heat exchanger 17 within a circuit of gas in the liquid state 8 partially represented in FIG. 1. As will be described in detail thereafter, the circuit of gas in the liquid state 8 allows gas in the liquid state to circulate, coming from the tank and going to the heat exchanger 17. The gas in the liquid state then returns into the tank after having flowed through said heat exchanger 17. The refrigerant fluid thereby cools the gas coming from the tank, within the heat exchanger 17. The gas in the liquid state, pumped into the tank is thus cooled further by the refrigerant fluid in the heat exchanger 17 then is sent into the tank in order to lower the average temperature of the tank and thereby allow the evaporated gas to condense and the internal pressure of the tank to be managed.

[0039] The purpose of the compression device 10 is to circulate the refrigerant fluid and to compress the refrigerant fluid to high pressure and high temperature. The fluid then circulates as far as the turbo-compressor 13. The turbo-compressor 13 comprises a compression member 14 and a turbine 15 mechanically linked to each other via a shaft 16. The shaft only links the compression member 14 to the turbine 15, the compression member 10 as such not being linked to the shaft 16. Such configuration thereby allows the compression device 10 and the compression member 14 to be rotated at a rotation speed different from each other.

[0040] The compression member 14 is arranged upstream of a first passage 23 of the internal heat exchanger 18 whereas the turbine 15 is arranged downstream of the first pass 23 of the heat exchanger 18. According to the example shown in FIG. 1, the turbine 15 is rotated by a driving member and thereby drives the shaft 16 that as such drives the compression member 14. According to another example, the driving member can rotate the compression member 14 which thereby drives the shaft 16 which as such drives the turbine 15. The additional exchanger 38, is as such interposed between the compression member 14 and the first passage 23 of the internal heat exchanger 18.

[0041] The refrigerant fluid is thus initially compresses by the compression member 14, then flows through the additional exchanger 38 where same is cooled by a third fluid e.g. by sea water. The cooling via the additional exchanger 38 subsequently allows a more efficient expansion by the turbine 15 to occur. The refrigerant fluid then flows through the first passage 23 of the internal heat exchanger 18 and is subsequently expanded by the turbine 15. The expansion produces a decrease in temperature of the refrigerant fluid that circulates through the heat exchanger 17 at low temperature in order to cool the gas in the liquid state coming from the tank, such as described hereinabove.

[0042] At the outlet of the heat exchanger 17, the refrigerant fluid then flows through a second passage 24 of the internal heat exchanger 18. An exchange of heat thus takes place between the refrigerant fluid circulating at first pressure within the first passage 23 of the internal heat exchanger 18 and the refrigerant fluid circulating at a second pressure lower than the first pressure, within the second passage 24 of the internal heat exchanger 18, in order to regulate the temperature of the refrigerant fluid circulating in the cooling circuit 4.

[0043] During the functioning of the cooling circuit, it is possible that the refrigerant fluid circulating in the main loop 22 is present in too large quantity or in too low quantity, which can hinder the functioning of the cooling circuit 3 and/or the cooling performances thereof. The monitoring of the quantity of refrigerant fluid in the main loop 22 is provided by a pressure sensor 27 arranged in the main loop 22 and measuring the pressure of the refrigerant fluid in real-time. The pressure measured is an indication of the quantity of refrigerant fluid present in the main loop 22, a too high pressure being related to an excess of refrigerant fluid and a too low pressure being related to a too low quantity of refrigerant fluid.

[0044] Moreover, in order to adjust the quantity of refrigerant fluid in the main loop 22, the cooling circuit 4 comprises a regulation branch 25 connected to the main loop 22. The regulation branch 25 comprises a valve 26 and extends up to a refrigerant fluid tank 28 and, if appropriate, to an outlet 29 to the atmosphere. In case of a non-conforming quantity of refrigerant fluid for an optimum cooling performance, the valve 26 can be opened to drive the circulation of refrigerant fluid into the regulation branch 25 in order to increase or decrease the quantity of refrigerant fluid in the main loop 22.

[0045] If the refrigerant fluid is present in excess in the main loop 22, the valve 26 opens in order that a given quantity of refrigerant fluid leaves the main loop 22 and circulates in the regulation branch 25 as far as the refrigerant fluid tank 28 or to the outlet 29 to atmosphere.

[0046] If the refrigerant fluid is present in too low quantity in the main loop 22, e.g. following an excess of refrigerant fluid escaping through the seals of the compression device 10 or of the turbo-compressor 13, the valve 26 opens in order that a given quantity of refrigerant fluid coming from the refrigerant fluid tank 28 circulates in the regulation branch 25 as far as the main loop 22.

[0047] In both cases described hereinabove, the valve 26 closes again once the quantity of refrigerant fluid present in the main loop 22 has reached an optimal quantity allowing the performances of the cooling circuit 4 to be maximized.

[0048] The opening and the closing of the valve 26 can depend on a signal emitted by the pressure sensor 27. The latter can thereby be configured to detect if the measured pressure of the refrigerant fluid exceeds a first pressure threshold, indicating an excess of refrigerant fluid in the main loop 22, in order to send a signal ensuring the opening of the valve 26 and the outlet of the refrigerant fluid.

[0049] The pressure sensor 27 can also detect if the measured pressure of the refrigerant fluid is below a second pressure threshold which is as such lower than the first pressure threshold. In such configuration, the above means that the refrigerant fluid is not present in a sufficient quantity in the main loop 22. The pressure sensor 27 can then send a signal ensuring the opening of the valve 26 and the inlet of the refrigerant fluid into the main loop 22, coming from the refrigerant fluid tank 28.

[0050] Preferentially, the regulation branch 25 is connected to the same section as the section where the refrigerant fluid pressure is measured by the pressure sensor 27. In FIG. 1, the pressure sensor 27 and the regulation branch 25 are positioned between the compression device 10 and the compression member 14 of the turbo-compressor 13. The cooling circuit 4 according to the invention thereby allows the quantity of refrigerant fluid circulating in the main loop 22 to be adjusted so as to perform an optimal cooling of the gas contained in the tank by means of the exchange of heat occurring in the heat exchanger 17.

[0051] FIG. 2 shows the cooling circuit 4 but with two regulation branches 25. The above is the only structural difference with the cooling circuit 4 shown in FIG. 1. We can thus refer to the description of same concerning all the elements common to the two representations of the cooling circuit 4 according to the invention.

[0052] The cooling circuit 4 shown in FIG. 2 thereby comprises a first regulation branch 71 and a second regulation branch 72. Each of the regulation branches 25 comprises its own valve 26, i.e. a first valve 73 positioned on the first regulation branch 71 and a second valve 74 positioned on the second regulation branch 72. The second regulation branch 72 is laid out at a low-pressure section of the main loop 22, more precisely between the second passage 24 of the internal heat exchanger 18 and the compression device 10. The first regulation branch 71 is positioned on the same section as the regulation branch 25 shown in FIG. 1. It should be noted that the cooling circuit 4 only includes one regulation branch 25 which can also be positioned on the section of the main loop 22 where the second regulation branch 72 shown in FIG. 2 is arranged and can alone ensure the inlet and/or outlet of refrigerant fluid into or out of the main loop 22.

[0053] The cooling circuit 4 also has two pressure sensors 27, including a first pressure sensor 75 measuring the pressure of the refrigerant fluid between the compression device 10 and the compression member 14 of the turbo-compressor 13, and a second pressure sensor 76 measuring the pressure of the refrigerant fluid between the second passage 24 of the internal heat exchanger 18 and the compression device 10. The fact of having two pressure sensors 27 allows the measurement of the pressure of the refrigerant fluid to be better controlled over time and a check to be made if one of the two pressure thresholds describe hereinabove has been crossed.

[0054] In FIG. 2, the first regulation branch 71 extends as far as the outlet 29 to the atmosphere while the second regulation branch 72 extends as far as the refrigerant fluid tank 28. It is thereby understood that the first regulation branch 71 is dedicated to an outlet, if any, of the refrigerant fluid out of the main loop 22 and the second regulation branch 72 is dedicated to an inlet, if any, of the refrigerant fluid into the main 22 loop. Such configuration is advantageous in that it is easier to discharge the refrigerant fluid out of the main loop 22 when the refrigerant fluid is at high pressure. It is also easier to inlet the refrigerant fluid into the main loop 22 when the refrigerant fluid circulating within the main loop is at low pressure. The opening and the closing of the valves 26 functions identically to what was described in FIG. 1, being dependent of the pressure of the refrigerant fluid measured by each of the pressure sensors 27.

[0055] FIG. 3 shows a first embodiment of a system for supplying and cooling a gas 1 comprising a cooling circuit 4 described hereinabove. The system for supplying and cooling a gas 1 can be laid out within a floating structure apt to transport and/or store gas in liquid form, e.g. within the tank 2. The gas is e.g. natural gas or ethane. The gas in liquid form is stored in the tank 2 at very low temperature. For various reasons, e.g. naturally during the transport, the gas in liquid form could partially evaporate at the blanket 200 of the tank 2.

[0056] The system for supplying and cooling a gas 1 comprises a supply circuit 3. The supply circuit 3 is configured to suction the evaporated gas formed in the blanket 200 of the tank 2. The gas could then be used as fuel for a first gas consuming apparatus 5 and/or a second gas consuming apparatus 6. As an example, the first gas consuming apparatus 5 could be an engine providing the propulsion of the floating structure and the second gas consuming apparatus 6 could be an auxiliary engine responsible for the electrical supply of the floating structure.

[0057] In FIG. 3, it is possible to observe that the compression device 10 ensuring the circulation of the refrigerant fluid within the cooling circuit 4 can also be used within the supply circuit 3 for compressing the evaporated gas so as to send the gas to the gas consuming apparatuses. If the latter do not require an input of energy via the gas, the gas could be eliminated e.g. via a burner 7. The compression device 10 could thus be used for one or other of the circuits.

[0058] If the refrigerant fluid is nitrogen, same is not compatible for supplying gas consuming apparatuses. In order to prevent deteriorations of the apparatuses while switching the compression device 10 from the cooling circuit 4 to the supply circuit 3, the cooling circuit 4 can be purged in order to completely remove the nitrogen, e.g. by means of the regulation branches 25 before using the compression device 10 for supplying the gas consuming apparatus.

[0059] In order to isolate the compression device 10 within the supply circuit 3 or within the cooling circuit 4, the system for supplying and cooling a gas 1 comprises an arrangement of valves. Thereby, a first valve 41 is arranged on the supply circuit 3 upstream of the compression device 10 and of the connection to the cooling circuit 4, a second valve 42 is arranged on the supply circuit 3 downstream of the compression device 10 and of the connection to the cooling circuit 4, a third valve 43 is arranged on the cooling circuit 4 downstream of the compression device 10 and of the connection to the supply circuit 3 and a fourth valve 44 is arranged on the cooling circuit 4 upstream of the compression device 10 and of the connection to the supply circuit 3.

[0060] Thereby, when the first valve 41 and the second valve 42 are in the open position and the third valve 43 and the fourth valve 44 are in the closed position, the compression device 10 is integrated into the supply circuit 3 for the purpose of compressing the gas for supplying the gas consuming apparatus.

[0061] When the first valve 41 and the second valve 42 are in the closed position and the third valve 43 and the fourth valve 44 are in the open position, the compression device 10 is integrated into the cooling circuit 4 for the purpose of compressing the refrigerant fluid for cooling the gas contained in the tank 2.

[0062] The system for supplying and cooling a gas 1 also comprises the circuit for the gas in the liquid state 8 mentioned hereinabove, within which the gas in the liquid state coming from tank 2 and flowing through the heat exchanger 17, circulates. The circuit for the gas in the liquid state 8 allows the gas being evaporated into the blanket 200 of the tank 2 to be condensed and thereby participates in the management of the tank pressure.

[0063] The gas in the liquid state of the tank 2 is suctioned into the circuit for the gas in the liquid state 8 by means of a pump 19. The gas in the liquid state then circulates until flowing through the heat exchanger 17. It is thereby understood that the exchange of heat occurring within the heat exchanger 17 takes place between the refrigerant fluid circulating in the cooling circuit 4 and the gas in the liquid state circulating in the circuit for the gas in the liquid state 8. The gas in the liquid state thereby cooled leaves the heat exchanger 17.

[0064] After having been cooled, the gas in the liquid state can return to the lower part of the tank 2 via an outlet orifice 21. Such an operation participates in lowering the average temperature of the tank 2, which leads to a lowering of the saturation pressure of the tank 2 and thereby a lowering of the pressure in the tank 2.

[0065] The cooled gas in the liquid state can also be sprayed in the form of a spray into the blanket 200 of the tank 2. To this end, the circuit for the gas in the liquid state comprises a spraying member 20 ensuring the spraying of the gas in the liquid state. The spraying of the gas in the liquid state allows the gas being evaporated into the blanket 200 of the tank 2, to condense. The condensation of the gas thereby decreases the quantity of evaporated gas which hence leads to a decrease in the internal pressure of the tank 2. In order whether or not to authorize the circulation of the gas in the liquid state, the circuit for the gas in the liquid state 8 comprises an additional valve 51.

[0066] The cooling circuit 4, more particularly the regulation branches 25 of same, is structurally and functionally identical to what has been described in FIGS. 1 and 2. One will thus refer to the description of the Figures for the functioning of the regulation branches 25.

[0067] FIG. 4 shows a second embodiment of a system for supplying and cooling a gas 1. The second embodiment is distinguished from the first embodiment in that same comprises a first compression device 11 and a second compression device 12. The first compression device 11 is installed in the supply circuit 3 whereas the second compression device 12 is installed within the cooling circuit 4. However, the function of the two compression devices is not defined by the location of the systems such as will be described in detail thereafter.

[0068] Moreover, the presence of two compression devices makes it possible to install a redundancy within the system for supplying and cooling a gas 1. Thereby, e.g., if one of the compression devices fails, the other compression device can still ensure the function thereof and keep the system for supplying and cooling a gas 1 operational.

[0069] The supply circuit 3 and the cooling circuit 4 both comprise a plurality of valves providing access to each of the compression devices so that the systems can both meet the need of gas supply to the gas consuming apparatus or the needs of supply of the refrigerant fluid of the cooling circuit. Thereby, in addition to the four valves already found in the first embodiment, the second embodiment of the system for supplying and cooling a gas 1 comprises a fifth valve 45, a sixth valve 46, a seventh valve 47, an eighth valve 48, a ninth valve 49 and a tenth valve 50.

[0070] The fifth valve 45 and the sixth valve 46 allow a connection to be made from the first compression device 11 to the cooling circuit 4 or else a connection from the second compression device 12 to the supply circuit 3, depending on the configuration of the system for supplying and cooling a gas 1.

[0071] The seventh valve 47 and the eight valve 48 are installed on either side of the first compression device 11 and allow the system to be isolated when the valves are in the closed position. The closing of the valves is useful in case of failure of the first compression device 11. The ninth valve 49 and the tenth valve 50 will allow same to be used to isolate the second compression device 12 from the rest of the system for supplying and cooling a gas 1.

[0072] All of the valves thereby allow a compression device to be dedicated to each of the circuits or else to dedicate both compression devices to the supply circuit 3 or to the cooling circuit 4. The fact of dedicating a compression device to each of the circuits allows for the simultaneous operation of the supply circuit 3 for supplying the gas to the gas consuming apparatus and to the cooling circuit 4 in order to cool the gas contained in the tank 2 using the refrigerant fluid. When both compression devices are dedicated to only one or other of the circuits, only one of the abovementioned functions is provided.

[0073] Like for the first embodiment, with the assumption of the refrigerant fluid being nitrogen, and in order to prevent deterioration of the gas consuming apparatus while switching the compression device 11 and/or the second compression device 12 from the cooling circuit 4 to the supply circuit 3, the cooling circuit 4 can be purged in order to completely remove the nitrogen, e.g. by means of the regulation branches 25 before using the compression device(s) for supplying the gas consuming apparatus.

[0074] The second embodiment is also distinguished from the first embodiment in that the first regulation branch 71 is linked to the refrigerant fluid tank 28 and in that the second regulation branch 72 is linked to the outlet 29 to the atmosphere. Such configuration can be implemented e.g. for the reasons of mechanical dimensions or stresses in the piping connections.

[0075] The rest of the system for supplying and cooling a gas 1 is structurally and/or functionally identical to what was described hereinabove or one will refer to the descriptions of FIG. 3 concerning the structural and functional details of the system for supplying and cooling a gas 1 and to the descriptions of FIGS. 1 and 2 concerning the structural and functional details of the cooling circuit 4.

[0076] Of course, the invention is not limited to the examples that have just been described and many adaptations can be made to said examples without departing from the scope of the invention.

[0077] The invention such has been just described, achieves indeed the goal set for same and allows a cooling circuit to be proposed that is apt to regulate a quantity of refrigerant fluid within the cooling circuit in order to optimize the cooling performances of a gas contained in the tank of the floating structure. Variants not described herein could be implemented without departing from the scope of the invention, as long as, according to the invention, the variants comprise a cooling circuit according to the invention.