System for supplying gas to at least one gas consuming device installed on a ship

Abstract

The present invention relates to a system (100) for supplying gas to at least one gas consuming device (300) installed on a ship (70), the supply system (100) comprising at least one gas supply pipe (123) for supplying gas to the at least one gas consuming device (300), the gas supply pipe (123) being configured to move gas taken in a liquid state from a tank (200) and subjected to a pressure lower than the pressure of the gas in the upper space (201) of the tank (200), and a first compression element (120) and a second compression element (130) configured to compress gas from the gas supply pipe (123) for supplying gas to the at least one gas consuming device (300), the first compression element (120) and the second compression element (130) being characterized in that, alternatively, the first compression element (120) and the second compression element (130) compress gas in a gaseous state from the gas supply pipe (123) and the gas taken in a gaseous state from the upper space (201) of the tank (200).

Description

[Technical Field]

[0001] The present invention relates to the field of ships having one or more engines powered by natural gas, making it possible to contain and / or transport liquefied natural gas. [Background technology]

[0002] Such ships typically include tanks that contain natural gas in a liquid state. Natural gas is liquid at atmospheric pressure and at temperatures below -162°C. Such tanks are never completely thermally insulated, and as a result, the natural gas at least partially vaporizes. Therefore, such tanks contain both liquid and gaseous natural gas. This gaseous natural gas forms a headspace above the tank, and the pressure in this headspace must be controlled to avoid damaging the tank. Therefore, as is known, at least a portion of the natural gas present in the tank in gaseous form is used, inter alia, to fuel the ship's engines.

[0003] However, when the ship is stopped, the natural gas present in the tanks in a gaseous state is no longer consumed by its engines, and therefore the consumption of natural gas by its engines is zero or almost zero. Therefore, re-liquefaction systems are installed on the ship, which enable the condensation of the vaporized natural gas present in the tanks, in order to return the vaporized natural gas in a liquid state to these tanks.

[0004] Systems for supplying engines and reliquefying gases that cannot be sent to these engines currently in use are very expensive. In particular, certain components of these supply systems are duplicated to ensure redundancy, that is, to guarantee a continuous supply to the engine even if one of these components fails. This is the case, for example, with the compressor that compresses the gas to a pressure that meets the engine's requirements. The present invention aims to overcome this drawback by proposing a gas treatment system that is at least as efficient but includes fewer components than current systems, making it possible to reduce the installation costs of such a system. Summary of the Invention

[0005] The present invention therefore relates to a system for supplying gas to at least one gas consuming device on board a ship, said supply system comprising: one gas supply pipe for supplying gas to at least one gas consuming device, the gas supply pipe being configured to receive gas taken from the tank in a liquid state and subjected to a pressure lower than the pressure of the gas in the headspace of the tank; a first compression element configured to compress gas from the gas supply line for supplying the gas to at least one gas consuming device; one second compression element; At least includes.

[0006] According to the present invention, the first compression element and the second compression element are: alternately The gas in gaseous state from the gas supply pipe and the gas taken in gaseous state from the head space of the tank are compressed.

[0007] Advantageously, the first and second compression elements are configured to independently supply at least one gas consumer, where it is understood that the two compression elements are configured to ensure that compressed gas is supplied to the gas consumer, and thus the two compression elements are redundant with respect to each other.

[0008] The ship includes a tank configured to contain liquefied gas. The term "tank headspace" means a portion of the tank where gas in a gaseous state accumulates, resulting from the natural evaporation of gas present in a liquid state in the rest of the tank. The term "tank bottom" means a portion of the tank extending from the bottom wall of the tank in a plane parallel to the bottom wall, the plane parallel to the bottom wall being located along the length of this line at most 20% of the total height of the tank measured along a line perpendicular to the bottom wall of the tank between the two ends of the tank. Advantageously, the plane parallel to the bottom wall involved in the definition of "tank bottom" can be located at 10% of the total height of the tank.

[0009] The at least one vapor consumer may for example be a DFDE (Dual Fuel Diesel Electric) generator, i.e. a gas consumer configured to supply power to a ship or an engine for propulsion of the ship, such as an ME-GI engine, an XDF engine, etc. It is understood that this is only one exemplary embodiment of the invention and that different gas consumers may be provided without departing from the context of the invention.

[0010] According to the present invention, advantageously, at least one gas consuming device makes it possible to at least partially consume gas present in gaseous state in the head space of the tank, thereby preventing the accumulation of this gas in the tank, which would result in an increase in the pressure to which the tank is subjected, which could damage the tank in the long term.

[0011] According to the invention, the first and second compression elements are interchangeable in the supply to at least one gas consumer. In other words, both the first and second compression elements are designed to compress gas in a gaseous state to a similar pressure that meets the requirements of at least one gas consumer. In this way, if one of the two compression elements fails, the other takes over, ensuring at low cost a continuous supply to at least one gas consumer while maintaining the tank's acceptable pressure, i.e., a pressure that does not risk damaging the tank.

[0012] Thus, both the first and second compression elements are configured to compress the gas from the supply line from a pressure lower than the pressure of the gas present in the headspace of the tank to a pressure equal to or higher than the pressure of the gas in the headspace of the tank. Each of the compression elements is therefore able to perform suction in the supply line thanks to the expansion caused upstream of this supply line when the supply line is under vacuum, i.e. when it is subjected to a pressure lower than the pressure of the gas present in the headspace of the tank. According to an exemplary application of the invention, the pressure of the gas in the headspace of the tank is equal to or approximately equal to 1.1 bar.

[0013] According to a feature of the invention, the system comprises at least one heat exchanger configured to perform heat exchange between the gas flowing in the supply pipe and the gas taken in liquid form from the tank. According to one embodiment of the invention, the heat exchanger can comprise at least one first passage configured to be supplied with the gas taken in liquid form from the tank of the ship, for example, and at least one second passage configured to be supplied with gas subjected to a pressure lower than the pressure of the gas in the headspace of the tank. Thus, according to this embodiment, the second passage of the heat exchanger participates in forming the supply pipe.

[0014] The system according to this embodiment of the invention comprises at least one first pump configured to supply a first passage of the heat exchanger, one second pump configured to supply a second passage of the heat exchanger, and at least one expansion means arranged in the supply pipe between the second pump and the second passage of the heat exchanger.

[0015] According to another embodiment of the invention, a heat exchanger is provided with one passage participating in the formation of the supply pipe, said heat exchanger being arranged inside the tank, i.e. in contact with the liquid gas contained in said tank, so that according to this embodiment of the invention, heat exchange takes place between the gas circulating in the first passage of the heat exchanger and subjected to a pressure lower than that of the gas in the headspace of the tank, and the gas present in the liquid state in the tank, which is in contact with the heat exchanger.

[0016] According to an operating mode of the system of the present invention, the first and second compression elements suck in gas taken from the headspace of the tank. According to this operating mode, the first and second compression elements are configured to compress the gas to a pressure that meets the requirements of at least one gas consumer. Alternatively, an expansion device can be arranged downstream of the first and second compression elements, and the expansion device is configured to reduce the pressure of the gas compressed by the first and / or second compression elements to a pressure that meets the requirements of at least one gas consumer. In other words, according to this alternative, the gas is compressed to a pressure higher than the pressure that meets the requirements of at least one gas consumer, and then the gas expands, i.e., its pressure is reduced to a pressure that meets the requirements of at least one gas consumer.

[0017] According to a feature of the present invention, the supply system includes only the first and second compression elements.

[0018] The supply system according to the invention may also comprise a system for re-liquefying the gas compressed by the at least one first compression element and / or by the second compression element, advantageously allowing gas in gaseous state not consumed by the at least one gas consumer to be recycled by condensing it and returning it to the tank.

[0019] According to one embodiment of the present invention, the reliquefaction system includes at least one first heat exchanger including at least one first passage configured to receive gas compressed by the first compression element and / or the second compression element and at least one second passage configured to receive gas taken in a gaseous state from the headspace of the tank. That is, it is understood that the first heat exchanger of the reliquefaction system is configured to exchange heat between the gas compressed by the first compression element and / or the second compression element and the gas taken in a gaseous state from the headspace of the tank. For example, the reliquefaction system may also include at least one second heat exchanger configured to exchange heat between the compressed gas from the first heat exchanger and the gas taken in a liquid state from the tank. In other words, the second heat exchanger includes at least one first passage configured to be supplied by the compressed gas leaving the first heat exchanger and at least one second passage configured to be supplied by the gas taken in a liquid state from the tank.

[0020] According to a feature of this embodiment of the invention, at least one first conduit is arranged between the first pump and the first passage of the heat exchanger, at least one additional conduit is arranged between the first conduit and the second heat exchanger, and at least one first control valve is arranged in this additional conduit, i.e., it is understood that the first pump is configured to supply at least the first passage of the heat exchanger and the second heat exchanger of the reliquefaction system.

[0021] The first control valve, located in the additional conduit, i.e., upstream of the second heat exchanger with respect to the direction of gas flow in this additional conduit, is configured to have an open position allowing liquid gas to flow in the additional conduit and a closed position preventing gas flow in this additional conduit. This is only an exemplary embodiment, and it will be understood that without departing from the context of the invention, the second pump can supply only the first passage of the heat exchanger and a third pump can be provided to supply the second heat exchanger.

[0022] Alternatively, the reliquefaction system does not have a second heat exchanger and the compressed gas from the first heat exchanger is returned directly to the tank, for example by means of a bubbler installed at the bottom of the tank. According to this alternative, the gas from the first heat exchanger is released in the form of bubbles which then condense in contact with the gas present in the tank in liquid state.

[0023] It is understood that these are only exemplary embodiments and that other reliquefaction systems compatible with the present invention may be contemplated.

[0024] According to a feature of the invention, the first compression element is configured to be supplied with gas having a pressure of at least 0.35 bar and at most 0.7 bar and to compress the gas to a pressure of at least 2 bar and at most 13 bar, and the second compression element is configured to be supplied with gas having a pressure equivalent to 1 bar and to compress the gas to a pressure of at least 5 bar and at most 20 bar.

[0025] According to a first exemplary embodiment of the present invention, at least one pipeline is arranged between the headspace of the tank and the intermediate inlet of the first compression element, and at least one control element is arranged in the at least one pipeline.

[0026] For example, the control device may be an all-or-nothing valve, i.e., a valve configured to have an open position that allows gas to flow through the pipeline, and a closed position that prevents gas from flowing through the pipeline.

[0027] According to a first exemplary embodiment, the first compression element comprises at least one main inlet, through which gas from the supply pipe is fed to the first compression element, and at least one intermediate inlet, through which gas taken in gaseous state from the headspace of the tank is fed to the first compression element, so that it is understood that the first compression element is designed to be fed selectively or simultaneously with vaporized gas and gas taken in gaseous state directly from the headspace of the tank.

[0028] Thus, according to this first exemplary embodiment, if the second compression element fails, the control element allows the gas to pass through the pipeline so that the gas taken in a gaseous state from the headspace of the tank can be compressed by the first compression element for delivery to the at least one gas consuming device. According to this first exemplary embodiment, the second compression element is configured to supply the gas taken in a gaseous state from the headspace of the tank to the at least one gas consuming device. In other words, regardless of which compression element fails, the supply of the gas taken in a gaseous state from the headspace of the tank to the at least one gas consuming device is guaranteed, and thus the pressure in the tank is maintained at a value allowed for this tank.

[0029] According to a second exemplary embodiment of the present invention, the first and second compression elements are arranged in series with each other. According to this second exemplary embodiment, at least one first conduit is arranged between the outlet of the first compression element and the inlet of the second compression element, and at least one pressure control means is arranged in the at least one first conduit. For example, the pressure control means can be an expansion element, i.e., an element configured to reduce the pressure of the gas flowing in the first conduit. Advantageously, this allows the first compression element to compress the gas evaporated by the heat exchanger with a sufficient pressure difference, ensuring correct operation of the first compression element and reducing wear. The gas compressed by the first compression element is thus expanded by the pressure control means before being compressed by the second compression element to a pressure suitable for the requirements of at least one gas consumer.

[0030] According to a second exemplary embodiment of the present invention, the first compression element is configured to be supplied with gas having a pressure of, for example, 0.35 bar to 0.7 bar and to compress this gas to a pressure of 2 bar to 6 bar, and the second compression element is configured to be supplied with gas having a pressure corresponding to or approximately corresponding to 1 bar and to compress this gas to a pressure of 5 bar to 20 bar.

[0031] Alternatively, the series of compressions compresses the gas to a pressure higher than the requirements of the at least one gas consuming device, and at least one expansion device is disposed between the second compression element and the at least one gas consuming device, and the expansion device is configured to reduce the pressure of the gas compressed by the first compression element and the second compression element to a pressure that meets the requirements of the at least one gas consuming device.

[0032] According to a second exemplary embodiment of the present invention, at least one second conduit can be arranged between the outlet of the second passage of the first heat exchanger and the inlet of the first compression element, and at least one first flow control means is arranged in this at least one second conduit. The first flow control means can, for example, be an all-or-nothing valve, i.e., a valve configured to take an open position that allows gas to flow in the second pipe and at least one closed position that prevents gas from flowing in the second pipe. Thus, according to this second exemplary embodiment, in the event of a failure of the first compression element, the gas consuming device is supplied with gas taken in a gaseous state from the headspace of the tank and compressed by the second compression element. In the event of a failure of the second compression element, the first flow control means can be placed in an open position so that gas taken in a gaseous state from the headspace of the tank can be supplied to the first compression element, thereby ensuring a supply of gas taken in a gaseous state from the headspace of the tank to the gas consuming device.

[0033] Alternatively, the first flow control means can be a pressure control element. According to this alternative, in the event of failure of the second compression element, the gas taken in gaseous state from the headspace of the tank is directed to the second pipe and expanded along the second pipe by the first flow control means, i.e., the pressure of the gas drops to a pressure corresponding to the pressure of the gas from the supply pipe, i.e., a pressure between 0.35 and 0.7 bar. This alternative therefore advantageously makes it possible to simultaneously supply the first compression element with gas taken in gaseous state from the headspace of the tank and gas taken in liquid state from the tank and vaporized by the supply pipe.

[0034] Therefore, the second exemplary embodiment of the present invention ensures an uninterrupted supply of gas taken in gaseous form from at least the headspace of the tank to at least one gas consuming device, thereby maintaining an acceptable pressure in the tank, i.e. a pressure that is unlikely to damage the tank.

[0035] According to a feature of the invention, the supply system comprises at least one means for distributing the gas in liquid state from the heat exchanger to the bottom of the tank, for example formed by a ramp including a plurality of orifices, according to this example distributed over the entire longitudinal length of the ramp, each of these orifices being designed to allow the gas in liquid state to exit from the heat exchanger.

[0036] Optionally, the outlet of the second heat exchanger of the reliquefaction system, through which the gas in liquid or two-phase state leaves this second heat exchanger, can also be connected to this distribution means in order to return the gas to the tank. Advantageously, such a ramp allows the gas in liquid state from the heat exchanger and / or from the second heat exchanger at the bottom of the tank to be distributed in such a way as to reduce the overall temperature of the gas present in liquid state in this tank, thus contributing to the suppression of evaporation phenomena which tend to cause the accumulation of gas in gaseous state in the tank. Alternatively, the distribution means is formed by a single pipeline.

[0037] The invention also relates to a ship for transporting liquefied gas, which ship comprises at least one liquefied gas cargo tank, at least one vaporized gas consumer and at least one system according to the invention for supplying gas to the gas consumer. The expression "liquefied gas cargo tank" refers both to a tank serving for the transport of liquefied gas, which also serves as a tank for liquefied gas used as fuel to supply at least one gas consumer, and to a tank which serves only as a tank for liquefied gas to supply at least one gas consumer.

[0038] According to a feature of the present invention, a ship comprises at least one first gas consuming device configured to be supplied with gas compressed at a first pressure and at least one second gas consuming device configured to be supplied with gas compressed at a second pressure, both of which are configured to be supplied with gas by at least one supply system according to the present invention, and the first supply pressure of the first gas consuming device is higher than the second supply pressure of the second gas consuming device.

[0039] The present invention also relates to a system integrating at least one land-based means for loading or unloading gas in liquid state with at least one vessel according to the invention for transporting gas in liquid state.

[0040] The invention also relates to a method for loading or unloading gas in liquid form from a gas carrier according to the invention. [Brief explanation of the drawings]

[0041] Other features, details and advantages of the invention will become more apparent on the one hand from reading the following description and on the other hand from reading the exemplary embodiments given by way of non-limiting example with reference to the attached drawings, in which:

[0042] [Figure 1] 1 shows a schematic diagram of a system for supplying gas to at least one gas consuming device according to a first exemplary embodiment of the present invention; [Figure 2] 2 illustrates a schematic diagram of a first mode of operation of the gas supply system according to the first exemplary embodiment shown in FIG. 1; [Figure 3] 2A and 2B illustrate a second mode of operation of the gas supply system according to the first exemplary embodiment shown in FIG. 1; [Figure 4] 2A and 2B schematically illustrate a third mode of operation of the gas supply system according to the first exemplary embodiment shown in FIG. 1; [Figure 5] 1 shows a schematic diagram of a gas supply system according to a first exemplary embodiment of the present invention, in which the first compression element has failed; [Figure 6] 1 shows a schematic diagram of a gas supply system according to a first exemplary embodiment of the present invention, in which the second compression element has failed; [Figure 7] 2 shows a schematic diagram of a system for supplying gas to at least one gas consuming device according to a second exemplary embodiment of the present invention; [Figure 8] 8 illustrates a schematic diagram of a first mode of operation of the gas supply system according to the second exemplary embodiment shown in FIG. 7; [Figure 9] 8A and 8B schematically illustrate a second mode of operation of the gas supply system according to the second exemplary embodiment shown in FIG. 7; [Figure 10] 8A and 8B schematically illustrate a third mode of operation of the gas supply system according to the second exemplary embodiment shown in FIG. 7. [Figure 11] 10 shows a schematic diagram of a gas supply system according to a second exemplary embodiment of the present invention, in which the first compression element has failed; [Figure 12] 10 shows a schematic diagram of a gas supply system according to a second exemplary embodiment of the present invention, in which the second compression element has failed; [Figure 13] 8A and 8B schematically illustrate a fourth mode of operation of the gas supply system according to the second exemplary embodiment shown in FIG. 7. [Figure 14] 8A and 8B schematically illustrate a fifth mode of operation of the gas supply system according to the second exemplary embodiment shown in FIG. 7. [Figure 15]A simplified schematic diagram of an LNG carrying tank and a terminal for loading and / or unloading this tank. DETAILED DESCRIPTION OF THE INVENTION

[0043] In the following description, the terms "upstream" and "downstream" are used to refer to the direction of gas flow through the element in question, whether in a liquid, gaseous, or two-phase state. In Figures 2-6 and 8-14, solid lines represent circuit portions through which gas in a liquid, gaseous, or two-phase state circulates, while dotted lines represent circuit portions through which gas does not circulate. The space in the tank 200 occupied by gas in its gaseous state is referred to as the "headspace 201 of the tank 200," and the terms "system 100 for supplying gas to at least one gas-consuming device 300," "supply system 100," and "system 100" are used synonymously.

[0044] The following description relates to two specific exemplary applications of the present invention, in which the ship's tank 200 contains natural gas, i.e., a gas consisting primarily of methane. It is understood that this is only one exemplary application, and that the system 100 for supplying gas to at least one gas consuming device 300 according to the present invention can be used with other types of gas, such as hydrocarbon gases or hydrogen gas. According to the present invention, the ship's tank 200 can function only as a container for containing gas for supplying gas to at least one gas consuming device 300, or the tank 200 can function both as a gas container and as a transport tank for this gas.

[0045] 1 and 7 schematically illustrate a gas supply system 100 in an off state according to a first exemplary embodiment of the present invention and a second exemplary embodiment of the present invention, respectively. The system 100 includes at least one heat exchanger 110, at least one first compression element 120, at least one second compression element 130, and at least one gas consuming device 300. According to either one of the first exemplary embodiment and the second exemplary embodiment of the present invention illustrated herein, the system 100 further includes a gas reliquefaction system 400.

[0046] Advantageously, according to both exemplary embodiments of the present invention, the supply system 100 comprises only two compression elements as compression means for supplying the gas consuming device 300, e.g., an engine. This is particularly advantageous considering the high cost of such components and the need to always have a spare means for supplying the gas consuming device 300.

[0047] The reliquefaction system 400 according to the present invention includes at least one first heat exchanger 410 and / or at least one second heat exchanger 420 arranged in series for at least one flow to pass through. The first heat exchanger 410 includes at least one first passage 411 configured to receive gas compressed by the first compression element 120 and / or the second compression element 130, and at least one second passage 412 configured to receive gas taken in a gaseous state from the headspace 201 of the tank 200. Meanwhile, the second heat exchanger 420 includes at least one first passage 421 configured to receive compressed gas flowing out of the first passage 411 of the first heat exchanger 410, and at least one second passage 422 configured to receive gas taken in a liquid state from the tank 200. As explained below, the gas taken in liquid form from the tank 200 may expand, i.e., its pressure may decrease, before being sent to the second passage 422 of the second heat exchanger 420.

[0048] The first heat exchanger 410 is therefore configured to exchange heat between the compressed gas and the gas taken in gaseous state from the headspace 201 of the tank 200. As a result, the compressed gas leaves the first passage 411 of the first heat exchanger 410 in gaseous state or in a two-phase state, i.e. a mixture of gas and liquid, and the gas taken in gaseous state from the headspace 201 of the tank 200 is warmed as it passes through the second passage 412 of the first heat exchanger 410. The gas heated as it passes through the first heat exchanger 410 is then sent to one of the compression elements 120 and 130 for compression and thereafter, at least partially, to the at least one gas consumer 300.

[0049] Meanwhile, the second heat exchanger 420 is configured to perform heat exchange between the two-phase gas from the first passage 411 of the first heat exchanger 410 and the gas taken in liquid state from the tank 200. As the two-phase gas passes through the second heat exchanger 420, it is condensed for subsequent return to the bottom 203 of the tank 200, and the gas taken in liquid state from the tank 200 is then heated as it passes through the second heat exchanger 420.

[0050] According to an example not shown in this specification, the reliquefaction system can be without a second heat exchanger. According to this example, the first passage of the first heat exchanger is connected to a bubble generator, for example, located at the bottom of the tank. The two-phase gas from the first heat exchanger is then discharged to the bottom of the tank in the form of bubbles that condense upon contact with the liquid gas present at the bottom of the tank.

[0051] The expression "bottom 203 of tank 200" means a portion of tank 200 extending between the bottom wall 202 of tank 200 and a plane parallel to bottom wall 202 that is positioned at most 20% of the total height h of the tank measured along a straight line perpendicular to bottom wall 202 of tank 200 between both ends of the tank 200.

[0052] Advantageously, the plane parallel to the bottom wall 202 involved in the definition of the "tank bottom" can be located at 10% of the total height h of the tank.

[0053] It is understood that these are only exemplary embodiments of the present invention, and that any other reliquefaction system compatible with the present invention may be used without departing from the context of the present invention, for example, a reliquefaction system may be provided that includes a different refrigeration fluid circuit.

[0054] According to the invention, the supply system 100 comprises at least one supply pipe 123 supplying at least one gas consuming device 300, the supply pipe 123 being configured to receive gas taken in liquid form from the tank 200 and subjected to a pressure lower than that of the gas in the headspace 201 of the tank 200. According to an exemplary application of the invention, the gas in the headspace 201 of the tank 200 has a pressure corresponding to or approximately corresponding to atmospheric pressure, i.e. a pressure of the order of 1 bar.

[0055] The supply system 100 according to the invention comprises at least one pump 141 arranged at the bottom 203 of the tank 200 and at least one expansion means 170 arranged between said pump 141 and the supply pipe 123, the pump 141 and the expansion means 170 being configured to ensure supply to the supply pipe 123. The following description provides an exemplary embodiment of said supply pipe 123, but it is understood that said supply pipe 123 can take different forms without departing from the context of the invention.

[0056] At least one first conduit 101 is disposed between the first pump 140 and the first passage 111 of the heat exchanger 110. At least one second conduit 102 is disposed between the second pump 141 and the second passage 112 of the heat exchanger 110. The first pump 140 and the second pump 141 are both disposed at the bottom 203 of the tank 200 for taking in gas in a liquid state and delivering it to the first passage 111 and the second passage 112 of the heat exchanger 110. A third conduit 103 extends between the second passage 112 of the heat exchanger 110 and the first compression element 120, and the second passage 112 and the third conduit 103 at least partially form the supply pipe 123 of the at least one gas consumer 300. More specifically, the third conduit 103 extends between the second passage 112 of the heat exchanger 110 and the main inlet 121 of the first compression element 120.

[0057] According to the invention, at least one expansion means 170 is arranged in the second conduit 102, i.e., between the second pump 141 and the second passage 112 of the heat exchanger 110. This expansion means 170 is therefore arranged to expand the liquid gas conveyed by the second pump 141, i.e., to reduce the pressure of this liquid gas before it joins the second passage 112 of the heat exchanger 110. In other words, the expansion means 170 arranged upstream of the heat exchanger 110 makes it possible to create a pressure difference between the gas flowing in the first passage 111 and the gas flowing in the second passage 112 of this heat exchanger 110. Thus, the liquid gas circulating in the first passage 111 of the heat exchanger 110 has a pressure that is the same or nearly the same as the pressure of the gas contained in the liquid state in the tank 200, while the gas circulating in the second passage 112 of the heat exchanger 110 has a pressure that is lower than the pressure of the gas contained in the liquid state in the tank 200. Therefore, the gas flowing through the second passage 112 is vaporized as it passes through the second passage 112 of the heat exchanger 110 .

[0058] As a result, heat exchange occurs within the heat exchanger 110 such that the liquid gas is cooled as it passes through the first passage 111 of the heat exchanger 110, and the expanded liquid gas is vaporized as it passes through the second passage 112 of the heat exchanger 110.

[0059] According to an exemplary embodiment of the invention not shown here, the heat exchanger may also include one first passageway supplied by a gas subjected to a pressure lower than that of the gas in the headspace of the tank and may be immersed in contact with the gas contained in liquid form in the tank. According to this exemplary embodiment, a heat exchange similar to that described above occurs between the expanded gas circulating in the heat exchanger and the liquid gas with which it is placed in contact.

[0060] An additional conduit 423 is disposed between the first conduit 101 and the second passage 422 of the second heat exchanger 420, and at least one first control valve 171 is disposed in the additional conduit 423. The first control valve 171 is configured to have an open position that allows liquid gas to circulate in the additional conduit 423, and a closed position that prevents gas from circulating in the additional conduit 423.

[0061] A fourth conduit 104 is arranged between the first passage 111 of the heat exchanger 110 and the bottom 203 of the tank 200. As shown, this fourth conduit 104 is arranged more particularly between the first passage 111 of the heat exchanger 110 and means 210 for distributing the gas in liquid state at the bottom 203 of the tank 200. According to the example shown here, this distribution means 210 is formed by a ramp 212 arranged at the bottom 203 of the tank 200. As will be explained in more detail below, this ramp 212 advantageously allows the gas cooled when passing through the heat exchanger 110 to be distributed at the bottom 203 of the tank 200. According to an exemplary embodiment not shown here, this distribution means 210 can simply be formed by the fourth conduit 104, which opens directly into the bottom 203 of the tank 200.

[0062] Meanwhile, a fifth conduit 105 extends between the first compression element 120 and a sixth conduit 106 connected to at least one gas consuming device 300. That is, the gas taken in liquid form from the tank 200 by the second pump 141 and vaporized as it passes through the second passage 112 of the heat exchanger 110 is intended to be supplied to at least one gas consuming device 300.

[0063] It can also be seen that a seventh conduit 107 is arranged between the second compression element 130 and the sixth conduit 106. This seventh conduit 107 makes it possible, in particular, to supply gas taken in gaseous form from the upper space 201 of the tank 200 and compressed by the second compression element 130 to at least one gas consuming device 300.

[0064] It will be understood that both the first compression element 120 and the second compression element 130 are designed to independently supply at least one gas consuming device 300. Thus, both the first compression element 120 and the second compression element 130 are configured to compress gas to a pressure suited to the requirements of the gas consuming device 300, i.e., to an absolute pressure of between 5 and 20 bar or to a pressure higher than 150 bar, depending on the type of gas consuming device 300 to be supplied. The first compression element 120 is further designed to compress gas from the second passage 112 of the heat exchanger 110 from a pressure lower than the pressure of the gas present in a gaseous state in the headspace 201 of the tank 200 to a pressure higher than or equal to the pressure of the gas present in a gaseous state in the headspace 201 of the tank 200. For example, the first compression element 120 is designed to compress gas from the second passage 112 of the heat exchanger 110 from an absolute pressure of 0.35 bar to 0.7 bar to a pressure higher than 1.1 bar, for example 5 bar to 20 bar, that meets the requirements of at least one gas consuming device 300.

[0065] The same applies to the second compression element 130, which is designed to compress the gas from the second passage 112 of the heat exchanger 110 from a pressure lower than the pressure of the gas present in gaseous state in the headspace 201 of the tank 200 to a pressure higher than or equal to the pressure of the gas present in gaseous state in the headspace 201 of the tank 200. For example, the second compression element 130 is designed to compress the gas from the second passage 112 of the heat exchanger 110 from an absolute pressure of between 0.35 and 0.7 bar to a pressure that is compatible with the requirements of the at least one gas consuming device 300, i.e. a pressure higher than 1.1 bar, for example between 5 and 20 bar.

[0066] According to an exemplary embodiment not shown in the drawings, the first and second compression elements are configured to compress the gas supplied to at least one gas consumer, respectively, to a pressure higher than that compatible with the requirements of the at least one gas consumer. According to this exemplary embodiment, at least one expansion device can be arranged downstream of the first and second compression elements and upstream of the gas consumer, and the expansion device is configured to reduce the pressure of the gas compressed by the first and / or second compression elements to a pressure compatible with the requirements of the gas consumer. For example, the expansion device can be arranged in the sixth conduit.

[0067] The eighth conduit 108 extends between the sixth conduit 106 and the aforementioned reliquefaction system 400, i.e., between the sixth conduit 106 and a first passage 411 of a first heat exchanger 410 of the reliquefaction system 400. As will be described in more detail below, at least one second control valve 180 is disposed in the eighth conduit 108 to either allow the compressed gas flowing through the sixth conduit 106 to pass therethrough or to prevent the compressed gas from passing therethrough. For example, the second control valve 180 may be an "all-or-nothing" type valve, i.e., a valve configured to have an open position that allows the compressed gas to pass through the eighth conduit 108 and a closed position that prevents the flow of gas through the eighth conduit 108.

[0068] A ninth conduit 109 is arranged between the second passage 412 of the first heat exchanger 410 and one of the compression elements 120, 130. In other words, this ninth conduit 109 enables the first compression element and / or the second compression element to ensure the supply of gas that is taken in a gaseous state from the upper space 201 of the tank 200 and intended to be supplied to at least one gas consuming device 300.

[0069] 1 , a pipeline 119 is also arranged between the ninth conduit 109 and the intermediate inlet 122 of the first compression element 120, and at least one control element 181 is arranged in this pipeline 119. The intermediate inlet 122 of the first compression element 120, through which gas taken in gaseous state from the headspace 201 of the tank 200 is supplied to this first compression element 120, is separated from the main inlet 121 of the first compression element 120, through which gas vaporized during passage through the heat exchanger 110 is supplied to this first compression element 120. These two separate inlets allow the first compression device 120 to be supplied with two different compression levels. Indeed, as previously mentioned, the vaporized gas leaves the heat exchanger 110 at a pressure lower than the pressure of the gas present in gaseous state in the headspace 201 of the tank 200. For example, the vaporized gas leaves the heat exchanger 110 at an absolute pressure of less than 1 bar, between 0.35 and 0.7 bar, while the gas taken in gaseous state from the headspace 201 of the tank 200 has an absolute pressure of about 1 bar. Thus, the intermediate inlet 122 allows the gas taken in gaseous state from the headspace 201 of the tank 200 to join the compressed stream from the heat exchanger 110 after intermediate compression. This is particularly true when the first compression element 120 and / or the second compression element 130 are multi-stage elements.

[0070] 7, at least one first conduit 128 is arranged between the fifth conduit 105 and the ninth conduit 109, and at least one pressure control means 182 is arranged in this first conduit 128. The first conduit 128 therefore extends between the outlet 124 of the first compression element 120 and the inlet 131 of the second compression element 130, allowing the gas vaporized by the heat exchanger 110 and compressed by the first compression element 120 to be supplied to the second compression element 130. The pressure control means 182 can be, for example, an expansion element configured to reduce the pressure of the gas compressed by the first compression element 120 before it is supplied to the second compression element 130. Furthermore, the pressure control means 182 is configured to assume a closed position that prevents gas from circulating in the first conduit 128. Advantageously, the pressure control means 182 ensures that there is a sufficient pressure difference between the inlet 125 and the outlet 124 of the first compression element 120 for the first compression element 120 to operate optimally. That is, gas is compressed by the first compression element 120 to a first pressure and expanded by the pressure control means 182 before being compressed again by the second compression element 130 to a pressure compatible with the requirements of the gas consuming device 300. For example, the first compression element 120 is configured to compress gas at a pressure of between 0.35 and 0.7 bar to a pressure of between 2 and 6 bar. The gas is then expanded by the pressure control means 182 to a pressure of approximately 1 bar, and the second compression element 130 is configured to compress the gas from 1 bar to a pressure of between 5 and 20 bar, i.e., a pressure compatible with the requirements of the gas consuming device 300.

[0071] At least one second conduit 129 is arranged between the ninth conduit 109 and the inlet 125 of the first compression element 120, and at least one first flow control means 183 is arranged in this second conduit 129. According to this second exemplary embodiment of the present invention, a second flow control means 184 is also arranged in the fifth conduit 105, i.e., between the first compression element 120 and the gas consuming device 300. For example, the first flow control means 183 and the second flow control means 184 may be "all-or-nothing" valves, i.e., valves configured to have an open position that allows gas to pass through the conduits in which they are arranged, and a closed position that prevents gas from passing through these conduits. Alternatively, as will be explained in more detail below with reference to Figure 13, the first flow control means 183 may be a pressure control element, i.e., an element configured to reduce the pressure of gas passing through it. According to yet another alternative, the first flow control means 183 may be an all-or-nothing valve, and a branch comprising a pressure control element may be arranged in parallel with this second conduit 129 comprising the first flow control means. The gas is configured to flow through the second conduit 129 or the branch parallel to this second conduit 129 depending on the operating mode of the system 100.

[0072] The second exemplary embodiment of the present invention differs from the first exemplary embodiment in that two gas recirculation pipes, not shown here, are provided in parallel with the first compression element 120 and the second compression element 130, respectively, and each of these recirculation pipes comprises at least one pressure control means. Advantageously, these pressure control means enable the first compression element 120 and the second compression element 130 to compress the gas supplied to them to different pressures, for example depending on the requirements of the at least one gas consuming device 300.

[0073] For example, the at least one gas consuming device 300 may be a DFDE (Dual Fuel Diesel Electric) generator, i.e. a gas consuming device configured to supply power to the vessel. The gas consuming device 300 may also be at least one propulsion engine of the vessel, such as an ME-GI engine or an XDF engine. It is understood that this is just one exemplary embodiment of the present invention and that different gas consuming devices may be provided without departing from the context of the present invention.

[0074] Now, with reference to the first exemplary embodiment of the present invention, three operating modes will be described: a first operating mode in which only a portion of the gas present in a gaseous state in the headspace 201 of the tank 200 is consumed by at least one gas consuming device 300, and another portion of this gas present in a gaseous state in the headspace 201 of the tank 200 is reliquefied by the reliquefaction system 400 before being returned to the tank bottom 203; a second operating mode and a third operating mode in which the amount of gas present in a gaseous state in the headspace 201 of the tank 200 to supply to the at least one gas consuming device 300 is insufficient, and gas is taken in a liquid state from the tank 200 and vaporized by the heat exchanger 110 to make up for this shortage. As described below, the second operating mode differs from the third operating mode in that in the second operating mode, at least one gas consuming device 300 is supplied with gas compressed by the first compression element 120 and gas compressed by the second compression element 130, whereas in the third operating mode, at least one gas consuming device 300 is supplied with gas compressed only by the first compression element.

[0075] 2 thus illustrates a first mode of operation of the system 100 according to a first exemplary embodiment of the present invention. As shown, the at least one gas consuming device 300 is supplied with gas taken in a gaseous state from the headspace 201 of the tank 200, which gas passes through a first heat exchanger 410 before being compressed by the second compression element 130 to a pressure suitable for the requirements of the at least one gas consuming device 300. A portion of the gas thus compressed is supplied to the gas consuming device 300, while another portion of this compressed gas is sent to the re-liquefaction system 400. This situation may arise, for example, when the gas consuming device 300 consumes less gas than is evaporated in the tank 200.

[0076] Thus, a portion of the compressed gas sent to the reliquefaction system 400 is first partially cooled in the first heat exchanger 410 by heat exchange with gas taken in gaseous state from the headspace 201 of the tank 200. This gas leaving the first heat exchanger 410 in gaseous or two-phase state completes its condensation by heat exchange carried out in the second heat exchanger 420 with gas taken in liquid state from the tank 200 and expanded by the first control valve 171. The gas thus condensed at the outlet of the second heat exchanger 420 is returned to the tank bottom through the fourth conduit 104. As mentioned above, this fourth conduit 104 is connected to a ramp 212 having a plurality of orifices 211 and configured to discharge and distribute the liquid gas reaching said ramp over its large surface.

[0077] Furthermore, the heat exchanger 110 is not powered, i.e. the second pump 141 is stopped. In fact, as mentioned above, this heat exchanger 110 makes it possible to vaporize the gas taken in liquid state from the tank 200 in order to supply it to the gas consuming device 300. If the gas present in gaseous state in the head space 201 of the tank 200 is sufficient to supply the gas consuming device 300, this heat exchanger 110 does not need to operate, and therefore the second pump 141 can be stopped.

[0078] On the other hand, if there is an insufficient amount of gas present in a gaseous state in the headspace 201 of the tank 200 to supply the gas consuming device 300, the second pump 141 is activated to supply the heat exchanger 110. This is shown, for example, in Fig. 3, which illustrates a second operating mode of the system 100 according to the first exemplary embodiment of the present invention. Thus, according to this second operating mode, the first pump 140 and the second pump 141 are both turned on to supply the heat exchanger 110 and thus to supply vaporized gas to the gas consuming device 300, and then the reliquefaction system 400 is turned off, i.e., the second control valve 180 is in its closed position, the first control valve 171 prevents gas from circulating in the additional pipe 423, and all of the gas present in a gaseous state in the headspace 201 of the tank 200 and compressed by the second compression element 130 is consumed by the gas consuming device 300. Therefore, according to this second operating mode, at least one gas consumption device 300 is supplied with gas that is taken in a liquid state from the tank 200, vaporized in the heat exchanger 110, and compressed by the first compression element 120, and also with gas that is taken in a gaseous state from the upper space 201 of the tank 200 and compressed by the second compression element 130.

[0079] As mentioned above, the supply system 100 according to the present invention also makes it possible to supply gas taken in gaseous state from the headspace 201 of the tank 200 and gas taken in liquid and vaporized state to at least one gas consuming device 300 in an advantageous manner using only the first compression element 120. Such an operating mode corresponds to the third operating mode shown in Figure 4.

[0080] This third operating mode differs from the second operating mode in particular in that the second compression element 130 is deactivated and the control element 181 is in an open position, allowing gas to circulate in the pipe 119. As previously mentioned, the gas vaporized during passage through the heat exchanger 110 reaches the first compression element 120, where it is compressed to a pressure suitable for the requirements of the gas consuming device 300. The gas taken in gaseous state from the headspace 201 of the tank 200 passes through the first heat exchanger 410, where it undergoes no temperature or pressure changes other than those related to its intake volume and the pressure drops inherent in the transport of this type of fluid, and it flows through the pipe 119 and joins the first compression element 120 through the intermediate inlet 122. The first compression element 120 is then configured to compress this gas to a pressure suitable for the requirements of the gas consuming device 300.

[0081] According to this third operating mode, the first compression element 120 can be, for example, a multi-stage compressor. In this way, the vaporized gas supplied to the first compression element 120 through the main inlet 121 is compressed to a pressure corresponding to the pressure of the gas present in the gaseous state in the headspace 201 of the tank 200. The intermediate inlet 122 of the first compression element 120 is then arranged so that the gas taken in the gaseous state from the headspace 201 of the tank 200 and the vaporized gas are mixed at a position in the first compression element 120 where the vaporized gas has already been compressed to the pressure of the gas present in the headspace 201 of the tank 200. The first compression element 120 is then designed to compress the gas mixture thus formed to a pressure suitable for the requirements of at least one gas consuming device 300.

[0082] Advantageously, this third operating mode also compensates for possible failure of the second compression element 130, i.e., makes it possible to maintain supply to at least one gas consuming device 300 with gas taken in gaseous state from the head space 201 of the tank 200 and gas taken in liquid state from the tank 200 and vaporized by the heat exchanger 110.

[0083] There is also a fourth operating mode, not shown here, called "equilibrium", in which the amount of gas contained in the headspace of the tank in gaseous state corresponds or approximately corresponds to the demand of at least one gas consuming device. Thus, according to this fourth operating mode, the first and second pumps are stopped, neither the heat exchanger nor the reliquefaction system is in operation, and the gas consuming device is supplied by the first or second compression element sucking in the gas present in gaseous state in the headspace 201 of the tank 200.

[0084] Figure 5 shows the gas supply system 100 according to a first exemplary embodiment of the present invention, in which the first compression element 120 has failed. It can be seen from this figure that in the event of a failure of the first compression element 120, the supply to the gas consuming device 300 remains guaranteed by gas taken in gaseous form from the headspace 201 of the tank 200, so that the pressure in the tank 200 can also be maintained at an acceptable value. In this situation, this figure 5 shows a mode identical to the first operating mode of the system 100 shown in figure 2.

[0085] 6 illustrates a first operating mode applied to the first exemplary embodiment, in which the second compression element 130 has failed. As illustrated, in the event of a failure of the second compression element 130, the control element 181 is opened to allow gas taken in gaseous form from the headspace of the tank 200 to reach the first compression element 120, where the pressure of the gas is increased to a pressure compatible with the requirements of the gas-consuming device 300. In this illustration illustrating the first operating mode, the reliquefaction system is operational, i.e., the second control valve 180 is open, the first pump 140 is operating to supply the second heat exchanger 420, and the heat exchanger 110 is off. In this respect, the description of FIG. 2 applies mutatis mutandis to FIG. 5.

[0086] The gas supply system 100 according to the first exemplary embodiment of the present invention thus allows a continuous supply of gas taken in gaseous state from the headspace 201 of the tank 200 to at least one gas consuming device 300, thereby ensuring that the pressure inside the tank 200 is maintained at a value acceptable for this tank 200, i.e. at a pressure that is unlikely to damage the tank 200. Also in parallel with this aspect, the two compression elements are designed to suck in the vaporized gas at an absolute pressure of between 0.35 and 0.7 bar in the first passage 112 of the heat exchanger 110 and to raise this gas to an absolute pressure of between 5 and 20 bar, or higher than 150 bar, depending on the gas consuming device 300 in question.

[0087] The description of the first operating mode just given with reference to the first exemplary embodiment also applies mutatis mutandis to the first operating mode of the second exemplary embodiment shown in Figure 8. That is, according to the first operating mode, the second pump 141 is stopped, all three of the pressure control means 182, the first flow control means 183 and the second flow control means 184 are in their closed positions, the first compression element 120 is off and the supply to the gas consuming device 300 is ensured by gas taken in gaseous state from the headspace 201 of the tank 200 and compressed by the second compression element 130. For the operation of the reliquefaction system the description given with reference to Figure 2 applies.

[0088] With respect to the second operating mode shown in FIG. 9, the system 100 according to the second exemplary embodiment differs from the first embodiment, particularly in that the first compression element 120 and the second compression element 130 act in series on the gas flow.

[0089] 9 illustrates a second mode of operation applied to a second exemplary embodiment of the present invention. In the following description, only the features that differentiate the second mode of operation applied to the second exemplary embodiment from the second mode of operation applied to the first exemplary embodiment will be described.

[0090] As shown, according to this second exemplary embodiment, the vaporized gas exiting the second passage 112 of the heat exchanger 110 is first compressed by the first compression element 120 and flows through the first conduit 128 to the second compression element 130 where it undergoes a second compression before being supplied to the gas consuming device 300. That is, the pressure control means 182 allows the gas to flow through the first conduit 128 and the first flow control means 183 and the second flow control means 184 are in their closed positions. According to the present invention, the vaporized gas leaves the heat exchanger 110 at an absolute pressure of between 0.35 and 0.7 bar and is compressed by the first compression element 120 to an absolute pressure of between 2 and 6 bar, advantageously to a pressure of about 3 bar. This gas, at an absolute pressure of about 3 bar, then passes through the first pipe 128, during which it undergoes expansion brought about by the pressure control means 182, i.e. its pressure is reduced to a pressure equal to or approximately equal to 1 bar. The gas is then compressed by the second compression element 130 to a pressure matching the requirements of the gas consuming device 300, for example a pressure between 5 bar and 20 bar, or higher than 150 bar, depending on whether the gas consuming device 300 is a so-called low-pressure consumer or a high-pressure consumer.

[0091] 10 shows a third operation mode of the second exemplary embodiment, in which at least one gas consuming device 300 is supplied with gas taken in liquid state from the tank 200, vaporized by the heat exchanger 110 and compressed by the first compression element 120, and also with gas taken in gaseous state from the headspace 201 of the tank 200 and compressed by the second compression element 130. Thus, as shown, according to this third operation mode, the pressure control means 182 and the first flow control means 183 are in their closed positions, and the second flow control means 184 is in its open position. Thus, the gas taken in gaseous state from the headspace 201 of the tank 200 passes through the first heat exchanger 410 and is sent to the gas consuming device 300 without significant changes in temperature or pressure in the first heat exchanger 410 before being compressed by the second compression element 130 to a pressure suitable for the requirements of the gas consuming device 300. The gas taken in liquid state from the tank 200 is vaporized thanks to the heat exchange taking place in the heat exchanger 110 and is compressed by the first compression element 120 to a pressure suitable for the requirements of the gas consuming device 300 so that it can be supplied to this gas consuming device 300. Thus, according to this second exemplary embodiment, the first compression element 120 is configured to compress the gas from the heat exchanger 110 from a pressure of 0.35 to 0.7 bar to a pressure of 5 to 20 bar or higher, depending on the gas consuming device being supplied, and the second compression element 130 is configured to compress the gas taken in gaseous state from the headspace 201 of the tank 200 from a pressure approximately equal to 1 bar to a pressure of 5 to 20 bar or higher, depending on the gas consuming device being supplied.

[0092] 5 and 6, the supply system 100 according to the second exemplary embodiment provides redundancy of compression elements 120, 130, on the one hand to ensure a continuous supply to the gas consuming device 300, and on the other hand to ensure that the pressure in the tank 200 is maintained at a value acceptable for this tank 200. Figures 11 and 12 illustrate this redundancy of compression elements 120, 130.

[0093] 11 shows a gas supply system 100 according to a second exemplary embodiment of the present invention in which the first compression element 120 has failed. As shown, in the event of a failure of the first compression element 120, the supply of gas taken in a gaseous state from the headspace 201 of the tank 200 to the gas consuming device 300 is ensured by the second compression element 130, and the pressure control means 182, the first flow control means 183, and the second flow control means 184 are all in their closed positions, i.e., preventing the circulation of gas in the first conduit 128, the second conduit 129, and the fifth conduit 105, respectively. In this situation, this FIG. 9 shows the same mode of operation as the first mode of operation of the system 100 shown in FIG. 8, and reference may be made to the explanation given above with reference to this FIG. 8.

[0094] 12 shows a system 100 for supplying gas to at least one gas consuming device 300 according to a second exemplary embodiment of the present invention, in which the second compression element 130 has failed. In this situation, the pressure control means 182 is moved to its closed position, so that gas does not flow through the first conduit 128, the first flow control means 183 is moved to its open position, and the second flow control means 184 is also moved to its open position. Thus, gas taken in a gaseous state from the headspace 201 of the tank 200 passes through the second conduit 129 to the first compression element 120, which is configured to compress the gas to a pressure suitable for the requirements of the gas consuming device 300. The gas thus compressed then passes through the fifth conduit 105 and the sixth conduit 106 to the gas consuming device 300. Meanwhile, the second pump 141 is stopped so that no heat exchange occurs in the heat exchanger 110.

[0095] As described above, if the first compression element 120 fails, the gas consuming device 300 is supplied with gas that has been taken in a gaseous state from the upper space 201 of the tank 200 and compressed by the second compression element 130. If the second compression element 130 fails, the first flow control means 183 opens to supply the gas that has been taken in a gaseous state from the upper space 201 of the tank 200 to the first compression element 120, and as a result, the gas that has been taken in a gaseous state from the upper space 201 of the tank 200 is supplied to the gas consuming device 300. Thus, the system 100 according to the second exemplary embodiment makes it possible to supply gas taken in a gaseous state from the headspace 201 of the tank 200 to the gas consuming device 300, ensuring that the pressure in the tank 200 is maintained at an acceptable value for the tank 200 under all circumstances, particularly in the event of failure of the first compression element 120 or the second compression element 130.

[0096] 13 and 14 illustrate fourth and fifth modes of operation of the system 100 according to the second exemplary embodiment of the present invention.

[0097] 13 therefore shows a fourth operating mode of the system 100. According to this fourth operating mode, the first flow control means 183 provided in the second conduit 129 is a pressure control element. This fourth operating mode corresponds to an operating mode in which the amount of gas taken in gaseous state from the headspace 201 of the tank 200 is insufficient to adequately supply the at least one gas consuming device 300. Therefore, the first pump 140 is operated so as to be able to supply the at least one gas consuming device 300 with gas vaporized by the heat exchanger 110. Furthermore, according to this fourth operating mode, the circulation of gas in the seventh conduit 107 is prevented, for example by means of an all-or-nothing valve not shown here, so that the gas taken in gaseous state from the headspace 201 of the tank 200 is directed towards the second conduit 129 and experiences expansion along this conduit caused by the first flow control means 183. Thus, gas taken in at an absolute pressure of about 1 bar is expanded to a pressure of between 0.35 bar and 0.7 bar so as to be mixed with gas taken in liquid state from tank 200 and vaporized by heat exchanger 110, and is then compressed by first compression element 120 and ultimately used to supply gas consuming device 300. In other words, this fourth operating mode advantageously makes it possible to supply first compression element 120, via the same inlet 125 of first compression element 120, with gas taken in liquid state from tank 200 and vaporized by heat exchanger 110, and gas taken in gaseous state from headspace 201 of tank 200.

[0098] 14 illustrates a fifth mode of operation of the system 100 according to the second exemplary embodiment. According to this illustrated fifth mode of operation, the system 100 is configured to supply two gas consuming devices 300, 301, a first gas consuming device 300 configured to be supplied with gas at a first pressure, and a second gas consuming device 301 configured to be supplied with gas at a second pressure that is lower than the first pressure.

[0099] According to this fifth operating mode, a tenth conduit 190 extends between the second flow control means 184 and the second gas consumer 301, so that the first compression element 120 and the second compression element 130 can supply gas in parallel and independently of each other to the first gas consumer 300 and the second gas consumer 301. An eleventh conduit 191 is also arranged between the tenth conduit 190 and the sixth conduit 106 connected to the first gas consumer 300, and this eleventh conduit 191 is provided with a pressure control element 192.

[0100] 14 corresponds to an operating mode in which the amount of gas present in a gaseous state in the headspace 201 of the tank 200 is insufficient to adequately supply the gas consumers 300, 301, and as a result the first pump 140 is activated to supply the heat exchanger 110. Thus, similar to what has been described above, the gas taken in a liquid state from the tank 200 is vaporized as it passes through the heat exchanger 110 and can then participate in the supply to the gas consumers 300, 301. Thus, according to this fifth operating mode, the first compression element 120 is configured to compress the gas taken in a liquid state from the tank 200 and vaporized as it passes through the heat exchanger 110 from an absolute pressure of 0.35 to 0.7 bar to a pressure of 2 to 6 bar, i.e. a pressure corresponding to the supply pressure of the second gas consumer 301. On the other hand, the second compression element 130 is configured to compress the gas taken in in a gaseous state from the upper space 201 of the tank 200 from an absolute pressure of approximately 1 bar to a pressure of 5 bar or more and 20 bar or less, which corresponds to the supply pressure of the first gas consumption device 300.

[0101] Optionally, the pressure control element 192 provided in the eleventh conduit 191 can be placed in an open position, so that gas compressed by the second compression element 130 can pass through this eleventh conduit 191. The gas from this second compression element 130 is thus expanded so that it can be supplied to the second gas consumer 301 if required.

[0102] 14 shows a situation in which the amount of gas taken in in liquid state and vaporized by the heat exchanger 110 is greater than the amount of gas required to supply the second gas consumer 301. In this case, the pressure control means 182 provided in the first conduit 128 is placed in its open position to allow gas compressed by the first compression element 120 to pass through this first conduit 128. As mentioned above, the control means 182 is configured to reduce the pressure of the gas passing through this control means 182. Thus, gas leaving the first compression element 120 at a pressure of between 2 and 6 bar undergoes expansion to a pressure of about 1 bar provided by the control means 182, and can be compressed by the second compression element 130 to a pressure of between 5 and 20 bar, mixed with gas taken in in gaseous state from the headspace 201 of the tank 200, to be supplied to the first gas consumer 300.

[0103] The description of the redundant system provided in the event of failure of the first compression element 120 or the second compression element 130 described above with reference to Figures 11 and 12 applies mutatis mutandis to these fourth and fifth operating modes.

[0104] Finally, Figure 15 is a simplified diagram of a vessel 70 showing a generally prismatic tank 200 mounted on the vessel's double hull 72, which contains natural gas in both liquid and gaseous states. The tank 200 may be part of an LNG carrier, but may also be a vessel in the case where the gas is operated as fuel for gas-consuming devices.

[0105] The wall of the tank 200 includes a primary sealing membrane intended to be in contact with the liquid state gas contained in the tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the vessel 70, and two insulating barriers arranged between the primary sealing membrane and the secondary sealing membrane and between the secondary sealing membrane and the double hull 72, respectively.

[0106] A loading and / or unloading pipeline 73 located on the upper deck of the vessel can be connected to a marine or port terminal using appropriate coupling devices to transfer the natural gas cargo in liquid form to or from the tank 200.

[0107] FIG. 15 also shows an example of a marine terminal having a loading and / or unloading station 75, an undersea pipeline 76, and an onshore facility 77. The loading and / or unloading station 75 is a fixed marine facility having a movable arm 74 and a tower 78 supporting the movable arm 74. The movable arm 74 carries a bundle of insulated pipes 79 that can be connected to pipes 73 for loading and / or unloading. The movable arm 74 can rotate to fit any size vessel. The loading and unloading station 75 allows for loading of a vessel 70 from the onshore facility 77 and / or unloading of a vessel 70 from the onshore facility 77. The onshore facility 77 includes a liquefied gas storage tank 80 and a connecting conduit 81 that is connected to the loading or unloading station 75 by an undersea pipeline 76. The subsea pipeline 76 allows the liquefied gas to be moved over long distances, e.g., 5 km, between the loading or unloading station 75 and the onshore facility 77, thereby allowing the vessel 70 to remain a long distance from shore during loading and / or unloading operations.

[0108] To generate the pressure required to move the liquefied gas, one or more discharge pumps provided in the loading and / or unloading tower of the tank 200 and / or pumps provided in the onshore facility 77 and / or pumps provided in the loading and unloading station 75 are used.

[0109] Of course, the invention is not limited to the examples described above, and many adjustments can be made to these examples without departing from the scope of the invention.

[0110] The invention therefore proposes a system for supplying gas to at least one gas consuming device, which system is installed on board the ship and allows the supply of the gas consuming devices present on board the ship at limited costs, since advantageously only two compression elements are required, while ensuring that the pressure in the tank containing the gas is maintained at an acceptable value for this tank under all circumstances.

[0111] However, the invention is not limited to the means and arrangements described and illustrated herein, but extends to any equivalent means and arrangements and to any technically possible combination of such means. In particular, features described with reference to various exemplary embodiments may be combined unless they are mutually inconsistent.

Claims

1. A gas supply system (100) for supplying gas to at least one gas consuming device (300) mounted on a ship (70), comprising: one gas supply pipe (123) for supplying gas to the at least one gas consuming device (300), the gas supply pipe (123) being configured to pass gas taken in a liquid state from the tank (200) and subjected to a pressure lower than the pressure of the gas in the head space (201) of the tank (200); a first compression element (120) configured to compress the gas from the gas supply pipe (123) for supplying the gas to the at least one gas consuming device (300); and at least one second compression element (130), a ninth conduit (109) for supplying gas taken in a gaseous state from the upper space (201) of the tank (200) to the second compression element (130); at least one second conduit (129) arranged between the ninth conduit (109) and an inlet (125) of the first compression element (120); and at least one first flow control means (183) arranged in the second conduit (129); When the first compression element (120) breaks down, the gas consumption device (300) is supplied with gas taken in a gaseous state from the upper space (201) of the tank (200) and compressed by the second compression element (130), When the second compression element (130) fails, the first flow control means (183) is opened to supply the gas taken in a gaseous state from the upper space (201) of the tank (200) to the first compression element (120), thereby supplying the gas taken in a gaseous state from the upper space (201) of the tank (200) to the gas consumption device (300).

2. 2. The gas supply system (100) of claim 1, comprising at least one heat exchanger (110) configured to perform heat exchange between the gas flowing in the gas supply pipe (123) and gas taken in a liquid state from the tank (200).

3. 3. The gas supply system (100) of claim 2, wherein the heat exchanger (110) includes at least one first passage (111) configured to be supplied with the gas taken in a liquid state from the tank (200) of the ship (70), and at least one second passage (112) configured to be supplied with the gas under a pressure lower than the pressure of the gas in the head space (201) of the tank (200).

4. 4. The gas supply system (100) of claim 3, comprising at least one first pump (140) configured to supply the first passage (111) of the heat exchanger (110), one second pump (141) configured to supply the second passage (112) of the heat exchanger (110), and at least one expansion means (170) arranged in the gas supply pipe (123) between the second pump (141) and the second passage (112) of the heat exchanger (110).

5. The gas supply system (100) according to any one of claims 1 to 4, wherein the first compression element (120) and the second compression element (130) suck in the gas taken in from the upper space (201) of the tank (200).

6. The gas supply system (100) according to any one of claims 1 to 5, comprising only the first compression element (120) and the second compression element (130) as compression elements.

7. 7. The gas supply system (100) according to any one of claims 1 to 6, comprising at least one re-liquefaction system (400) for gas compressed by the first compression element (120) and / or by the second compression element (130).

8. 8. The gas supply system of claim 7, wherein the reliquefaction system includes at least one first heat exchanger including at least one first passageway configured to pass gas compressed by the first compression element and / or the second compression element, and at least one second passageway configured to pass gas taken in a gaseous state from the upper space of the tank.

9. 9. The gas supply system (100) of claim 8, wherein the reliquefaction system (400) includes at least one second heat exchanger (420) configured to perform heat exchange between compressed gas from the first passage (411) of the first heat exchanger (410) and gas taken in a liquid state from the tank (200).

10. 10. The gas supply system (100) of claim 1, wherein the first compression element (120) is configured to be supplied with gas having a pressure of 0.35 bar to 0.7 bar and to compress the gas to a pressure of 2 bar to 13 bar, and the second compression element (130) is configured to be supplied with gas having a pressure equivalent to 1 bar and to compress the gas to a pressure of 5 bar to 20 bar.

11. 11. The gas supply system (100) according to claim 1, wherein at least one pipeline (119) is arranged between the headspace (201) of the tank (200) and an intermediate inlet (122) of the first compression element (120), and at least one control element (181) is arranged on the at least one pipeline (119).

12. The gas supply system (100) of any one of claims 1 to 10, wherein the first compression element (120) and the second compression element (130) are connected in series with each other.

13. 13. The gas supply system (100) of claim 12, wherein at least one first conduit (128) is arranged between an outlet (124) of the first compression element (120) and an inlet (131) of the second compression element (130), and at least one pressure control means (182) is arranged in the at least one first conduit (128).

14. at least one re-liquefaction system (400) for the gas compressed by said first compression element (120) and / or by said second compression element (130); The reliquefaction system (400) includes at least one first heat exchanger (410) including at least one first passage (411) configured to pass gas compressed by the first compression element (120) and / or the second compression element (130), and at least one second passage (412) configured to pass gas taken in a gaseous state from the headspace (201) of the tank (200), 14. The gas supply system (100) of claim 13, wherein the at least one second conduit (129) is disposed between the outlet of the second passage (412) of the first heat exchanger (410) and the inlet (125) of the first compression element (120).

15. 15. The gas supply system (100) of any one of claims 12 to 14, wherein the first compression element (120) is configured to be supplied with gas having a pressure of 0.35 bar to 0.7 bar and to compress the gas to a pressure of 2 bar to 6 bar, and the second compression element (130) is configured to be supplied with gas having a pressure corresponding to or approximately corresponding to 1 bar and to compress the gas to a pressure of 5 bar to 20 bar.

16. A ship (70) for transporting liquefied gas, comprising at least one tank (200) for a liquefied gas cargo, at least one vaporized gas consumer (300), and at least one gas supply system (100) according to any one of claims 1 to 15, for supplying gas to the at least one gas consumer (300).

17. 17. A ship (70) according to claim 16, comprising at least one first gas consuming device (300) configured to be supplied with gas compressed at a first supply pressure, and at least one second gas consuming device (301) configured to be supplied with gas compressed at a second supply pressure, wherein both the first gas consuming device (300) and the second gas consuming device (301) are configured to be supplied with gas by the at least one gas supply system (100), and wherein the first supply pressure of the first gas consuming device (300) is higher than the second supply pressure of the second gas consuming device (301).

18. 18. A gas supply system (100) for loading or unloading gas in a liquid state, the gas supply system (100) integrating at least one land-based means and at least one vessel (70) for transporting said gas in a liquid state as claimed in claim 17.

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