Gas supply system for high and low pressure gas consuming appliances

Abstract

Title of the invention: Gas supply system for high and low pressure gas consuming devices The present invention relates to a gas supply system (1) for a high pressure gas consuming device (4) of a floating structure (20) comprising at least one tank (8), comprising: - at least a first supply circuit (2) for the high pressure consuming device (4), comprising a first heat exchanger (6), a second heat exchanger (7), a pump (10); characterized in that the supply system (1) comprises a pre-cooling system (17) for the first heat exchanger (6) configured to take gas in the liquid state from the tank (8), the pre-cooling system (17) comprising a pre-cooling line (19) and a valve (21) for regulating the circulation of the gas within the pre-cooling line (19). Abstract figure: Figure 1

Description

Title of the invention: Gas supply system for high and low pressure gas consuming appliances

[0001] The present invention relates to the field of vessels for storing and / or transporting gas in the liquid state and more particularly concerns a gas supply system for consumer devices included within such vessels.

[0002] During a journey made by a ship comprising a tank of gas in the liquid state intended to be consumed and / or to be delivered to a destination point, said ship may be able to use at least a portion of said gas in the liquid state in order to supply at least one of its engines, via a gas supply system. This is the case for ships equipped with a ME-GI type propulsion engine. In order to supply this type of engine, the gas must be compressed to very high pressure by special compressors capable of compressing the gas up to 300 bars, but such compressors are expensive, generate significant maintenance costs and induce vibrations within the ship.

[0003] An alternative to installing these high-pressure compressors is to vaporize the gas in liquid form at 300 bars before it is sent to the propulsion engine. Since such a solution does not allow the removal of the gas in vapor form (or BOG, which in English means "boil-off gas") forming naturally within a tank containing at least part of the cargo, low-pressure compressors can be installed to supply an auxiliary engine, capable of consuming the gas in vapor form at low pressure.

[0004] The use of such a gas supply system, however, requires preparation, which corresponds to pre-cooling, during which some of its components are brought to a temperature below a threshold value from which the supply of the engines can begin. The size of the components which it is necessary to bring to temperature is likely to vary the time necessary for such pre-cooling; thus, the preparation of large components will delay the activation of the gas supply system, even if smaller components are already at temperature.

[0005] The present invention aims to overcome this drawback by proposing a gas supply system in which the time required to heat up large components, such as a heat exchanger, is reduced so as to accelerate the start-up time of the gas supply system.

[0006] The present invention thus has as its main object a gas supply system of at least one high-pressure gas-consuming device and at least one low-pressure gas-consuming device of a floating structure comprising at least one tank configured to contain the gas, the supply system comprising: at least a first gas supply circuit of the high-pressure gas-consuming device, comprising at least a first pump configured to pump the gas taken in the liquid state from the tank, at least a first heat exchanger, a second heat exchanger, a second pump arranged between the first heat exchanger and the second heat exchanger and at least one high-pressure evaporator configured to evaporate the gas circulating in the first gas supply circuit;at least one second gas supply circuit for the low-pressure gas-consuming device, comprising at least one compressor configured to compress gas taken in the vapor state from the tank to an operating pressure of the low-pressure gas-consuming device. According to the invention, the supply system comprises a pre-cooling system for the first heat exchanger configured to take gas in the liquid state from the tank, the pre-cooling system comprising a pre-cooling line connected to the first supply circuit between the first heat exchanger and the second pump, the pre-cooling system comprising at least one valve for regulating the circulation of the gas within the pre-cooling line. ;

[0007] The supply system according to the invention is for example intended to equip a floating structure in order to supply gas to its consuming devices. More particularly, the first gas supply circuit makes it possible to meet the fuel needs of the high-pressure gas consuming device. The latter may for example be the means of propulsion of the floating structure, for example an ME-GI engine. The first supply circuit extends from the tank to the high-pressure gas consuming device. The first pump is installed at the bottom of the tank and ensures the pumping of the gas in the liquid state so that it can circulate in the first supply circuit.

[0008] Since the gas must be in the vapor state to be able to supply the high-pressure gas-consuming device, the high-pressure evaporator ensures the evaporation of the gas before it is supplied to the high-pressure gas-consuming device. The high-pressure evaporator is the site of an exchange of calories between the gas in the liquid state circulating in the first supply circuit and a heat transfer fluid, for example glycolated water, sea water or water vapor. The latter must be at a sufficiently high temperature to create a change of state of the gas so that the latter passes into the vapor or supercritical state in order to supply the high-pressure gas-consuming device.

[0009] Before the gas in the liquid state circulating in the first supply circuit is vaporized by means of the high-pressure evaporator, the gas in the liquid state passes through the first heat exchanger, then the second heat exchanger. For this, the first heat exchanger and the second heat exchanger are connected to each other by a portion of the first supply circuit so that the gas in the liquid state can pass through the two heat exchangers successively. The temperature of said gas in the liquid state thus tends to increase before it passes through the high-pressure evaporator. Thus, the gas circulating in the first supply circuit can be in a two-phase state at the outlet of the second heat exchanger.

[0010] Generally speaking, the gas contained in the tank can pass naturally, or forced by the floating structure, into the vapor state. The gas within the tank passing into the vapor state must be evacuated so as not to create excess pressure within the tank. Such a function is ensured by the second gas supply circuit of the low-pressure gas-consuming device. Such a second supply circuit extends from the tank to the low-pressure gas-consuming device. The latter can for example be an auxiliary engine such as an electric generator. The compressor arranged on the second supply circuit is responsible for sucking the gas present in the tank's crown in order to be able to both supply the low-pressure gas-consuming device, but also to regulate the pressure within the tank. At the compressor outlet, the gas in the vapor state can supply the low-pressure gas-consuming device.

[0011] The first heat exchanger, the second heat exchanger and the high-pressure evaporator are here physically distinct heat exchangers. For example, the first heat exchanger is a recondenser and the second heat exchanger is a pre-cooler. The second pump makes it possible to increase the pressure of the gas in the liquid state circulating in the first supply circuit, so that the latter has a pressure compatible with supplying the high-pressure gas-consuming device.

[0012] The supply system comprises a system for pre-cooling the first heat exchanger which is used to bring this first heat exchanger to temperature during a preparation step or pre-cooling step of the floating structure. During the preparation step, the temperature of the first heat exchanger is for example lowered to approximately -140°C. Such a preparation step is usually carried out when the floating structure is at the dock, prior to supplying its consumer devices. For this purpose, the supply system is configured to take gas in the liquid state from the tank, if necessary by circulating it in a portion of the first supply circuit extending between the first pump and the first heat exchanger. The supply system comprises the pre-cooling line, which is connected to the first supply circuit at the outlet of the first heat exchanger and upstream of the second pump, and which is used to evacuate from the first heat exchanger the gas having passed through it for pre-cooling. The passage of the gas within this pre-cooling line is governed by the presence of the control valve of the pre-cooling system. This control valve has an open configuration and a closed configuration, a passage of gas in the pre-cooling line being permitted in the open configuration of the control valve. The presence of the pre-cooling circuit makes it possible to pre-cool the first heat exchanger independently of a pre-cooling of the second pump.

[0013] The pre-cooling system makes it possible to lower the temperature of the first heat exchanger prior to its operation within the supply system. To do this, the pre-cooling system increases the gas flow rate passing through the first heat exchanger, so as to accelerate the time required for it to reach temperature. The pre-cooling system makes it possible, for example, to double or triple the gas flow rate circulating within the first heat exchanger compared to a gas flow rate usually used during operation of the first heat exchanger in order to supply the high-pressure gas-consuming device.Thus, the time required to prepare the entire fuel system is reduced, as the first heat exchanger can be brought up to temperature in a time similar to that required to bring other, less large components of the fuel system up to temperature, such as the second pump.

[0014] According to an optional characteristic of the invention, the first supply circuit comprises a first valve arranged between the first pump and the first heat exchanger and a second valve arranged between the first heat exchanger and the second pump, the pre-cooling line being connected to the first supply circuit between the first heat exchanger and the second valve.

[0015] The first valve and the second valve constitute a bypass circuit of the first heat exchanger. Such a bypass circuit, associated with the pre-cooling system, makes it possible in particular to carry out a purge of a first pass of the heat exchanger, which is arranged between these two valves. In such a case of bypassing the first heat exchanger, it is possible to simultaneously pre-cool the first heat exchanger and supply gas to the second pump. The use of the bypass circuit also makes it possible to carry out maintenance operations on the first heat exchanger.

[0016] According to an optional characteristic of the invention, the pre-cooling system is configured so that the pre-cooling line opens into a lower portion of the tank.

[0017] According to an optional characteristic of the invention, the pre-cooling system is configured so that the pre-cooling line opens into an upper portion of the tank.

[0018] In other words, the pre-cooling line extends between the first supply circuit and the tank. The tank comprises a lower portion dedicated to the storage of gas in the liquid state and an upper portion dedicated to the storage of gas evaporated from the gas in the liquid state, the lower portion corresponding to a tank bottom and the upper portion corresponding to a tank top. The pre-cooling line may, according to different embodiments, open either at the tank bottom or in the tank top. In both cases, the pre-cooling line opens directly into the tank, i.e. it is not connected to any other pipe of the supply system in order to open into the tank.

[0019] According to an optional characteristic of the invention, the supply system comprises a gas return line connected to the second supply circuit and configured to return the gas to the tank, the first heat exchanger and the second heat exchanger each comprising a first pass constituting the first supply circuit and a second pass constituting the return line.

[0020] In other words, the first heat exchanger and the second heat exchanger are each configured to carry out a heat exchange between the gas circulating in the return line in the vapor state and the gas in the liquid state circulating in the first supply circuit. This return line is arranged between the compressor and the low-pressure gas-consuming device and it extends to the tank. At the outlet of the compressor, the gas in the vapor state circulates through the return line if the low-pressure gas-consuming device does not require a fuel supply. The gas in the vapor state circulating in the return line initially passes through the second heat exchanger, then the first heat exchanger, before returning to the tank.Thanks to the heat exchange taking place between the gas in the liquid state circulating in the first supply circuit and the gas in the vapor state circulating in the return line, the temperature of the gas in the vapor state decreases while passing through the heat exchangers, until said gas condenses and returns to the liquid state substantially at the outlet of the first heat exchanger. The recondensed gas then circulates to the tank. The first heat exchanger is configured to condense the gas circulating within the return line. The first heat exchanger is the exchanger crossed by the gas in the liquid state of the first supply circuit when said gas in the liquid state is at its lowest temperature. This is . so the exchange of calories taking place within the first heat exchanger which will change the state of the gas circulating in the return line to make it pass from the vapor state to the liquid state. The second heat exchanger is configured to pre-cool the gas circulating within the return line, prior to its passage within the first heat exchanger.

[0021] According to an optional characteristic of the invention, the pre-cooling line is connected to the return line between the first heat exchanger and an outlet of the return line configured to open into the tank.

[0022] In other words, the pre-cooling line comprises a first end connected to the first supply circuit and a second end connected to the return line at the outlet of the first heat exchanger, more precisely between the second pass of this first heat exchanger and the tank. Such a configuration makes it possible to avoid the manufacture and installation of a dedicated line portion up to the tank.

[0023] According to an optional characteristic of the invention, the supply system comprises a system for cooling the second pump, the cooling system comprising a cooling line connected to the first supply circuit between an inlet port of the second pump and the second heat exchanger, the cooling system comprising at least one valve for controlling the circulation of the gas within the cooling line.

[0024] The cooling system of the second pump is the counterpart of the pre-cooling system of the first heat exchanger. The cooling system of the second pump is thus used during the step of preparing the supply system in order to lower the temperature of the second pump prior to its operation within the supply system. For this purpose, the cooling system takes gas in the liquid state and increases the flow rate of this gas in the liquid state passing through the second pump, so as to bring it up to temperature. The cooling line is either connected directly to the second pump, or connected to the first supply circuit between this second pump and the second heat exchanger.

[0025] Depending on the case, chronologically the cooling of the second pump via the cooling system can be implemented after the pre-cooling of the first heat exchanger by the pre-cooling system, simultaneously with it or even before it.

[0026] According to an optional characteristic of the invention, the cooling system is configured so that the cooling line opens into the tank.

[0027] In other words, the cooling line extends between the pump and the tank. The cooling line may, depending on the embodiments, open out at the bottom of the tank or into the tank sky.

[0028] According to an optional characteristic of the invention, the cooling line opens into the return line between the first heat exchanger and the outlet of the return line configured to open into the tank.

[0029] Thus, the cooling line extends between the inlet port of the second pump and the outlet of the second pass of the first heat exchanger. After precooling the second pump, the gas in the liquid state circulates within the cooling line and then takes the return line to be conducted to the tank. Such a configuration makes it possible to avoid the manufacture and installation of a dedicated portion of line up to the tank.

[0030] For embodiments where the return line opens into the bottom of the tank, the outlet of this return line may be equipped with an ejection member such as a bubbling member. This makes it possible to liquefy at least part of the gas in the vapor state when the latter returns to the tank, also causing an increase in temperature of the gas in liquid form present in the tank.

[0031] According to an optional characteristic of the invention, the return line comprises an expansion member arranged between the first heat exchanger and an outlet of the return line configured to open into the tank.

[0032] The expansion member allows the pressure of the gas circulating in the return line to be lowered, once it has condensed during its passage through the first heat exchanger. Thanks to the expansion member, the gas in the liquid state is returned to the tank at a temperature close to the liquid-vapor equilibrium temperature of the gas. The expansion member also has the role of regulating the flow rate of gas to be condensed circulating in the return line. When one and / or the other of the pre-cooling line and the cooling line open into the return line, they are connected between this expansion member and the outlet of the return line, that is to say they are connected downstream of the expansion member.

[0033] According to an optional characteristic of the invention, the supply system comprises a bypass line of the first heat exchanger, this bypass line comprising a regulation member.

[0034] This bypass line and the regulating member which it carries participate in forming the bypass system of the first pass of the first heat exchanger.

[0035] The invention also relates to a floating structure for storing and / or transporting gas in the liquid state, comprising at least one tank configured to contain gas in the liquid state, at least one high-pressure gas-consuming device, at least one low-pressure gas-consuming device and at least one system for supplying gas to these consuming devices as mentioned above.

[0036] The invention further covers a system for loading or unloading liquid gas which combines at least one onshore and / or port installation and at least one floating structure for storing and / or transporting liquid gas as mentioned above.

[0037] The invention relates to a method for loading or unloading a liquid gas from a floating gas storage and / or transport structure as mentioned above, in which pipelines for loading and / or unloading gas in the liquid state arranged on an upper deck of the floating structure can be connected, by means of appropriate connectors, to a maritime or port terminal in order to transfer the gas in the liquid state from or to the tank.

[0038] The invention finally relates to a method for supplying a floating structure as mentioned above by a supply system as mentioned above, comprising at least one preliminary pre-cooling step comprising a sub-step of sampling gas in the liquid state in the tank, a sub-step of cooling the first heat exchanger and a sub-step of circulating the gas within the pre-cooling line, the supply method comprising a step of supplying the high-pressure gas-consuming apparatus with gas in the liquid state taken from the tank.

[0039] Thus, the pre-cooling step is necessary for the implementation of the supply system in order to supply in particular its high-pressure gas-consuming device; it makes it possible to bring the first heat exchanger up to temperature to allow such supply of the high-pressure gas-consuming device, and also subsequently allows the condensation of the gas circulating within the return line.

[0040] According to an optional characteristic of the invention, during the pre-cooling step the control valve of the pre-cooling system is open.

[0041] Opening this control valve allows the gas to pass through the pre-cooling line.

[0042] According to an optional characteristic of the invention, the supply method comprises at least one cooling step prior to the supply step, comprising a sub-step of sampling gas in the liquid state in the tank, a sub-step of cooling the second pump and a sub-step of circulating the gas within the cooling line.

[0043] During this cooling step, the gas in the liquid state circulates either within the first heat exchanger, and more precisely its first pass, or within the bypass line of the bypass circuit. The cooling step is for example simultaneous with the pre-cooling step.

[0044] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and on the other hand, examples of embodiment given for informational and non-limiting purposes with reference to the attached drawings on the other hand, in which:

[0045] [Fig.l] illustrates, schematically, a gas supply system according to the invention according to a first embodiment;

[0046] [Fig.2] illustrates, schematically, the gas supply system of [Fig.l] according to a second embodiment;

[0047] [Fig.3] illustrates, schematically, the gas supply system of [Fig.l] according to a third embodiment;

[0048] [Fig.4] illustrates, schematically, the gas supply system of [Fig.l] according to a fourth embodiment;

[0049] [Fig.5] illustrates, schematically, the gas supply system of [Fig.l] according to a fifth embodiment;

[0050] [Fig.6] illustrates, schematically, a tank of a floating structure according to the invention and of a loading and / or unloading terminal for this tank.

[0051] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0052] In the figures, the elements common to several figures retain the same reference. The terms “upstream” and “downstream” used in the following description are used to express positions of components within gas circuits in the liquid state or in the vapor state and refer to the direction of circulation of said gas within said circuit.

[0053] Figures 1 to 5 thus illustrate, schematically, a gas supply system 1 according to the invention, which is here integrated within a floating structure. The supply system 1 makes it possible to circulate gas which may be in the liquid state, in the vapor state, in the two-phase state or in the supercritical state, and this from a storage and / or transport tank 8 and to a high-pressure gas-consuming device 4 and / or a low-pressure gas-consuming device 5 in order to supply the latter with fuel.

[0054] Said floating structure may for example be a ship capable of storing and / or transporting gas in the liquid state. The supply system 1 is in this case capable of using the gas in the liquid state that the floating structure stores and / or transports to supply the high-pressure gas-consuming device 4, which may by example being a propulsion engine, and the low-pressure gas-consuming device 5, which could for example be an electric generator supplying the floating structure with electricity.

[0055] In order to ensure the circulation of the gas contained in the tank 8 to the high-pressure gas-consuming device 4, the supply system 1 is provided with a first gas supply circuit 2. The first supply circuit 2 comprises a first pump 9 arranged within the tank 8. The first pump 9 makes it possible to pump the gas in the liquid state and to circulate it in particular within the first supply circuit 2. By sucking in the gas in the liquid state, the first pump 9 also makes it possible to raise the pressure thereof to a value between 6 and 17 bars.

[0056] The gas in the liquid state, in a direction of circulation going from the tank 8 to the high-pressure gas-consuming device 4, passes through a first heat exchanger 6, is pumped by a second pump 10 and passes through a second heat exchanger 7. The second pump 10 makes it possible to raise the pressure of the gas in the liquid state to a value between 30 and 70 bars for use with liquefied petroleum gas, and preferably between 150 and 400 bars for use with ethane, ethylene or even with liquefied natural gas consisting mainly of methane.

[0057] After passing through the second heat exchanger 7, the gas circulates to a high-pressure evaporator 11. The high-pressure evaporator 11 makes it possible to modify the state of the gas circulating in the first supply circuit 2 in order to change it to the vapor or supercritical state. Such a state makes the gas compatible for supplying the high-pressure gas-consuming device 4. The evaporation of the gas to the liquid state can, for example, be done by heat exchange with a heat transfer fluid at a temperature high enough to evaporate the gas to the liquid state, here glycolated water, sea water or water vapor.

[0058] Thanks to the combination of the second pump 10 and the high-pressure evaporator 11, the gas is at a pressure and in a state compatible for supplying the high-pressure consumer device 4. Such a configuration makes it possible to avoid the installation of high-pressure compressors on the first supply circuit 2 which present cost constraints and generate strong vibrations.

[0059] Within the tank 8, a portion of the gas cargo can naturally pass into the vapor state and diffuse into a tank headspace 12, which corresponds to an upper portion of the tank 8, as opposed to a tank bottom 16 which corresponds to a lower portion thereof. In order to avoid overpressure within the tank 8, the gas in the vapor state contained in the tank headspace 12 must be evacuated. However, the first supply circuit 2 is configured to use the gas in the liquid state to supply the high-pressure gas-consuming device 4.

[0060] The supply system 1 comprises a second gas supply circuit 3, which uses the gas in the vapor state to supply the low-pressure gas-consuming device 5. The second supply circuit 3 therefore extends between the tank canopy 12 and the low-pressure gas-consuming device 5. In order to suck in the gas in the vapor state contained in the tank canopy 12, the second supply circuit 3 comprises a compressor 13. In addition to sucking in the gas in the vapor state, the compressor 13 also makes it possible to raise a pressure of the gas in the vapor state circulating in the second supply circuit 3 to a pressure of between 6 and 20 bars absolute, so that the gas in the vapor state is at a pressure compatible with supplying the low-pressure gas-consuming device 5. The second supply circuit 3 thus makes it possible to supply the low-pressure gas-consuming device 5 while regulating the pressure within the tank 8 by sucking in the gas in the vapor state present in the tank canopy 12. tank 12.

[0061] The presence of gas in the vapor state in excessive quantity within the tank ceiling 12 causes an overpressure within the tank 8. It is therefore necessary to evacuate the gas in the vapor state in order to lower the pressure within the tank 8. The excess gas in the vapor state can then for example be eliminated by a burner 18. However, the supply system 1 according to the invention comprises a return line 14 which extends from the second supply circuit 3 to the tank 8.

[0062] The return line 14 is connected to the second supply circuit 3 downstream of the compressor 13 relative to a direction of circulation of the gas in the vapor state circulating in the second supply circuit 3. Depending on the direction of circulation of the gas in the vapor state circulating in the return line 14, said gas passes through the second heat exchanger 7 initially, then passes through the first heat exchanger 6. The exchange of calories taking place within the first heat exchanger 6 and the second heat exchanger 7 is therefore between the gas in the liquid state circulating in the first supply circuit 2 and the gas in the vapor state circulating in the return line 14.

[0063] The objective of this heat exchange is to condense the gas in the vapor state of the return line 14, so that it passes into the liquid state and returns to the tank 8 in this state, instead of being eliminated by the burner 18. More precisely, the gas circulating in the return line 14 is in the vapor state at the inlet of the first heat exchanger 6 and leaves in the liquid state due to the heat exchange taking place within the first heat exchanger 6. It is understood from the above that the first heat exchanger 6 and the second heat exchanger 7 each comprise a first pass constituting the first supply circuit 2 as well as a second pass constituting the return line 14.

[0064] In order to align the pressure of the gas circulating in the return line 14 with the pressure prevailing in the tank 8, the return line 14 may comprise an expansion member 15, arranged between the first heat exchanger 6 and an outlet of the return line 14 opening into the tank 8, which lowers the gas pressure to a pressure of between 1 and 3 bars absolute. Once the gas is condensed in the first heat exchanger 6 and then expanded in the expansion member 15, the latter continues its course to the outlet of the return line 14, that is to say to the tank 8. The first heat exchanger 6 therefore acts as a condenser or recondenser.

[0065] The second heat exchanger 7 is located downstream of the first heat exchanger 6 in the direction of circulation of the gas in the first supply circuit 2, and upstream of the first heat exchanger 6 in the direction of circulation of the gas in the return line 14. The second heat exchanger 7 therefore ensures pre-cooling of the gas in the vapor state circulating in the return line 14 before it is condensed within the first heat exchanger 6; in other words, the second heat exchanger 7 is a pre-cooler. At the first supply circuit 2, the gas in the liquid state at the inlet of the second heat exchanger 7 has previously passed through the first heat exchanger 6 and has been pumped by the additional pump 10, which has therefore increased its temperature and pressure.It is thus possible that following the exchange of calories occurring at the second heat exchanger 7, the gas circulating within the first supply circuit 2 leaves the second heat exchanger 7 in a two-phase state. The temperature of the gas circulating in the return line 14 is therefore lowered after passing through the second heat exchanger 7, implementing the pre-cooling indicated above in relation to the second heat exchanger 7.

[0066] It should be noted that in order to be able to optimally and without delay ensure its function as a condenser for the gas circulating in the return line 14, the first heat exchanger 6 must be pre-cooled. Such pre-cooling, which will be described later in relation to a method for supplying the floating structure 20, is a step prior to the implementation of the first heat exchanger 6 as a condenser for the return line 14.

[0067] For this purpose, according to the invention the supply system 1 comprises a pre-cooling system 17 for the first heat exchanger 6. The supply system 1 and its pre-cooling system 17 are illustrated according to a first embodiment in [Fig. 1], according to a second embodiment in [Fig. 2], according to a third embodiment in [Fig. 3], according to a fourth embodiment in [Fig. 4] and according to a fifth embodiment in [Fig. 5].

[0068] The pre-cooling system 17 comprises a pre-cooling line 19 which is connected differently within the supply system 1 according to the embodiments, as well as a regulating valve 21 for the circulation of the gas within the pre-cooling line 19. This regulating valve 21 is carried by the line of pre-cooling 19 and controls the circulation of gas in vapor state or gas in liquid state within it.

[0069] The pre-cooling system 17 is configured to take gas in the liquid state from the tank 8, if necessary using the first pump 9, and to convey it to the first heat exchanger 6. The gas in the liquid state is conveyed to the first heat exchanger 6 via a pipe of the first supply circuit 2 connecting the tank 8 to the first heat exchanger 6. This pipe therefore participates both in the supply of the high-pressure gas-consuming device 4 and in the pre-cooling of the first heat exchanger 6. The first heat exchanger 6 is pre-cooled when it is crossed by the gas in the liquid state; it is thus understood that the greater the flow rate of gas in the liquid state passing through the first heat exchanger 6, the more quickly the temperature of this first heat exchanger 6 will be lowered.

[0070] In addition to the pre-cooling system 17, the supply system 1 comprises a cooling system 24 for the second pump 10; this cooling system 24 makes it possible, during a step prior to supplying the high-pressure gas-consuming device 4, to circulate gas in the liquid state within the second pump 10 to bring it to a suitable temperature. The cooling system 24 comprises, on the one hand, a cooling line 28 and, on the other hand, a control valve 29 which is carried by the cooling line 28. It is understood that the control valve 29 controls the circulation of the gas within the cooling line 28.

[0071] The cooling system 24 is configured to take gas in the liquid state from the tank 8, if necessary using the first pump 9, and to convey it to the second pump 10. The gas in the liquid state is conveyed to the second pump 10 in particular via the pipe of the first supply circuit 2 which connects the tank 8 to the first heat exchanger 6. This pipe therefore participates both in the supply of the high-pressure gas-consuming device 4, in the pre-cooling of the first heat exchanger 6 and in the cooling of the second pump 10.

[0072] The cooling line 28 is connected to the first supply circuit 2 between an inlet port of the second pump 10 and the second heat exchanger 7. Thus, either the cooling line 28 is connected to the second pump 10, as illustrated in the figures, or it is connected to the first supply circuit 2 between an outlet of this second pump 10 and an inlet of the second heat exchanger 7.

[0073] The control valve 29 is a proportional valve, which has a fully open configuration, a closed configuration, and at least one intermediate configuration in which it is partially open. When the control valve is in its closed configuration, the passage of gas to the liquid state within the cooling line 28 is prevented. Conversely, when the second pump 10 is cooling, the control valve 29 is in its fully open configuration.

[0074] The cooling line 28 extends, for the first four embodiments, from the first supply circuit 1 to the tank 8. In the embodiments of FIGS. 1 to 4, the cooling line 28 extends more precisely to the upper portion of the tank 8, that is to say that it opens into the tank crown 12. However, without departing from the scope of the invention, it is possible to envisage alternative embodiments in which the cooling line 28 would open into the tank bottom 16. It should be noted that the control valve 29 which governs the passage of gas within the cooling line 28 has a function of expanding the gas to the liquid state.Thus, the gas in the liquid state circulating in the cooling line 28 has a pressure of the order of 9 bars between the second pump 10 and the control valve 29, that is to say upstream of this control valve 29, and a pressure of less than 2 bars, that is to say close to that of the gas in the liquid state in the tank 8, between the control valve 29 and the tank 8, that is to say downstream of the control valve 29.

[0075] With regard to the pre-cooling system 17, in the five embodiments presented here the pre-cooling line 19 of the first heat exchanger 6 is connected to the first supply circuit 2 between this first heat exchanger 6 and the second pump 10. The control valve 21 comprises an open configuration, in which the gas can circulate within the pre-cooling line 19, and a closed configuration in which such circulation is prohibited. It is understood that in this open configuration, the gas is at least partially diverted towards the pre-cooling line 19, while in the closed configuration the gas circulates to the second pump 10.The pre-cooling circuit 17 thus makes it possible to increase the flow rate of gas circulating within the first heat exchanger 6 without impacting the flow rate of gas which is sent to the second pump 10, an excess flow rate of gas being diverted into the pre-cooling line 19.

[0076] In the first embodiment and in the second embodiment, which are respectively illustrated in Figures 1 and 2, the pre-cooling line 19 extends between the first heat exchanger 6 and the second pump 10 on the one hand and the tank 8 on the other hand. In other words, the pre-cooling line 19 extends from the first supply circuit 2 to the tank 8. In Figures 1 and 2, the pre-cooling line 19 extends more precisely to the upper portion of the tank 8, that is to say that it opens into the tank crown 12. As has been specified for the cooling line 28, it would however be possible to envisage alternative embodiments in which the pre-cooling line 19 would open into the tank bottom. 16.

[0077] It should be noted that in the second embodiment, the supply system 1 uses a bypass circuit 32 of the first heat exchanger 6. This bypass circuit 32 comprises a bypass line 33 arranged in parallel with the first pass of the first heat exchanger 6, as well as a regulating member 34 carried by said bypass line 33.

[0078] The bypass circuit 32 makes it possible to prevent gas from passing through the first heat exchanger 6, in particular for the purpose of purging the latter, for example during a maintenance operation on said first heat exchanger 6. To do this, the bypass circuit 32 is used in conjunction with valves arranged on the first supply circuit 2 on either side of the first heat exchanger 6, with more precisely a first valve 35 arranged upstream of the heat exchanger 6 and a second valve 36 arranged downstream thereof. As illustrated in [Fig. 2], the bypass line 33 is connected to the first supply circuit 2 upstream of the first valve 35 and downstream of the second valve 36.In other words, the bypass line 33 extends in parallel with the first supply circuit 2 between, on the one hand, a first point between the tank 8 and the first heat exchanger 6, more precisely between the tank 8 and the first valve 35, and on the other hand a second point between the first heat exchanger 6 and the second pump 10, more particularly between the second valve 36 and the second pump 10. It is understood that the first and second valves 35, 36 are not integrated into the bypass circuit 32 but that they form part of a portion of the first supply circuit 2 that the bypass circuit 32 makes it possible to avoid.

[0079] The regulating member 34, when open, allows a passage of gas in the liquid state within the bypass line 33. The first valve 35 allows a passage of gas in the liquid state within the first pass of the first heat exchanger 6 when it is open and prevents such a passage when it is closed. The second valve 35 allows the circulation of gas to the second pump 10 and by extension to the high-pressure gas-consuming device 4 when it is open and prevents such a passage when it is closed. It follows from the above that the purging of the first heat exchanger 6 is implemented when the regulating member 34 is open, the first valve 35 is closed and when the pre-cooling system 17 is in operation, that is to say when the regulating valve 21 is in its open configuration.

[0080] It should be noted that the bypass circuit 32 can also be used when the first heat exchanger 6 has temperatures that are too high, which would risk vaporizing the gas circulating within it, which would risk damaging the second pump 10 which would then be supplied with gas in the vapor state rather than with gas in the liquid. The bypass circuit 32 makes it possible, in this context, to bypass the first heat exchanger 6 and thus to ensure that the second pump 10 is always supplied with gas in the liquid state so as to allow its optimal operation.

[0081] Furthermore, thanks to the second embodiment of [Fig. 2], it is possible to carry out, simultaneously, a supply of the high-pressure gas-consuming device 4 and a pre-cooling of the first heat exchanger 6. In this case, the regulating member 34 is open, so that gas in the liquid state can circulate in the bypass line 33 then again within the first supply circuit 2 to the high-pressure gas-consuming device 4. The second valve 36 is closed in order to prevent a reflux of the gas towards the first heat exchanger 6. In parallel, the first valve 35 is open, so that a portion of gas in the liquid state coming from the tank 8 passes through the first heat exchanger 6 before circulating within the pre-cooling line 19. To do this, the regulating valve 21 of this pre-cooling line 19 is in its open configuration.A mixture between the gas having passed through the first heat exchanger 6 and the gas having circulated within the bypass line 33 is prevented by the second valve 36 which is closed. The second embodiment therefore makes it possible to manage the pre-cooling of the first heat exchanger 6 while supplying the high-pressure gas-consuming device 4, which in particular makes it possible to start the floating structure simultaneously with the heating of the first heat exchanger 6.

[0082] The third embodiment, which is illustrated in [Fig. 3], differs from the first embodiment of [Fig. 1] in that the pre-cooling line 19 is not connected directly to the tank 8; in other words, the pre-cooling line 19 does not open into the tank 8. Here, on the contrary, the pre-cooling line 19 is connected to the cooling line 28. More precisely, the pre-cooling line 19 is connected to the cooling line 28 downstream of the control valve 29, that is to say between this control valve 29 and the tank 8. The pre-cooling line 19 then extends from the first supply circuit 2 to the cooling line 28.

[0083] In the fourth embodiment, shown in [Fig. 4], the pre-cooling line 19 also does not open directly into the tank 8. Here, the pre-cooling line 19 is connected to the return line 14 by a convergence point 37. More particularly, the pre-cooling line 19 is connected to the return line 14 at the convergence point 37 downstream of the expansion member 15, that is to say between this expansion member 15 and the outlet of the return line 14 which opens into the tank 8. If necessary, the outlet of the return line 14 can be equipped with an ejection member such as a bubbling member, not shown here. In this fourth embodiment, as mentioned previously, the cooling line 28 opens into the tank 8.

[0084] The fifth embodiment, illustrated in [Fig. 5], is a variant of the fourth embodiment. Indeed, in this fifth embodiment the pre-cooling line 19 is connected to the return line 14 downstream of the expansion member 15 within the convergence point 37 as is the case in the fourth embodiment. The fifth embodiment, however, differs from this fourth embodiment with regard to the connection of the cooling line 28. Thus, here the cooling line 28 is also connected to the return line 14 at the convergence point 37. It follows from the above that the pre-cooling line 19 and the cooling line 28 are both connected to the return line 14 via the convergence point 37.

[0085] It should be noted that since they are not incompatible, the characteristics presented in relation to one of the five embodiments are, unless otherwise stated, likely to apply, mutatis mutandis, to one or more other of these embodiments without departing from the scope of the invention.

[0086] [Fig. 6] is a cutaway view of a floating structure 20 which shows the tank 8 which contains the gas in the liquid state and in the vapor state, this tank 8 being of generally prismatic shape mounted in a double shell 22 of the floating structure 20. The wall of the tank 8 comprises a primary sealing membrane intended to be in contact with the gas in the liquid state contained in the tank 8, a secondary sealing membrane arranged between the primary sealing membrane and the double shell 22 of the floating structure 20, and two thermally insulating barriers arranged respectively between the primary sealing membrane and the secondary sealing membrane and between the secondary sealing membrane and the double shell 22.

[0087] Pipelines 23 for loading and / or unloading gas in the liquid state arranged on the upper deck of the floating structure 20 can be connected, by means of appropriate connectors, to a maritime or port terminal to transfer the cargo of gas in the liquid state from or to the tank 8.

[0088] [Fig. 6] also represents an example of a maritime or port terminal comprising loading and / or unloading equipment 25, an underwater pipeline 26 and an onshore and / or port installation 27. The onshore and / or port installation 27 may for example be arranged on the quay of a port, or according to another example be arranged on a concrete gravity platform. The onshore and / or port installation 27 comprises liquid gas storage tanks 30 and connecting pipelines 31 connected by the underwater pipeline 26 to the loading and / or unloading equipment 25.

[0089] To generate the pressure necessary to transfer the gas to the liquid state, we put in operation of the pumps equipping the land and / or port installation 27 and / or the pumps equipping the floating structure 20.

[0090] A method of supplying the floating structure 20 using the supply system 1 will now be described. Such a supply method comprises two distinct parts, namely a first part which corresponds to a preparation of the supply system 1 and a second part which is the supply as such of one and / or the other of the consumer devices 4, 5.

[0091] Thus, the supply method comprises a step of pre-cooling the first heat exchanger 6 which is prior to a step of supplying one and / or the other of the gas-consuming devices 4, 5. The supply method also comprises here a step of cooling the second pump 10, which is also prior to the step of supplying the gas-consuming devices 4, 5.

[0092] The pre-cooling step allows the first heat exchanger 6 to be brought up to temperature. This pre-cooling step begins with a sub-step of sampling gas in the liquid state in the tank 8, during which gas in the liquid state is sampled from the tank 8 using, for example, the first pump 9 and then circulates within the first supply circuit 2 to the first heat exchanger 6. The pre-cooling step then comprises a sub-step of cooling the first heat exchanger 6, which corresponds to a circulation of the gas in the liquid state through the heat exchanger 6. The gas is then evacuated from the first heat exchanger 6 and circulates in the pre-cooling line 19 with a view to its return to the tank 8 during a circulation sub-step. For this purpose, the control valve 21 is in its open configuration.The gas is returned to the tank 8 either directly, as is the case for the first and second embodiments; or via the cooling line 28 as described previously for the third embodiment; or finally via the return line 14 in the context of the fourth and fifth embodiments.

[0093] During the pre-cooling step according to the first, third, fourth and fifth embodiments, the bypass circuit 32 is not used, so that the regulating member 34 is closed. Conversely, the first valve 35 and the second valve 36 are both open.

[0094] The sub-steps of sampling, pre-cooling and circulation are implemented continuously and simultaneously until a temperature of -140°C is obtained within the first heat exchanger 6. The time required to obtain such a temperature is for example one hour, such a duration being improved here thanks to the increase in flow rate within the first heat exchanger 6 that the pre-cooling system 17 allows. It should be noted that at the start of the pre-cooling step, the first heat exchanger 6 has a particular temperature particularly high; in fact, it vaporizes the gas in the liquid state which is delivered to it, and it is therefore gas in the vapor state which circulates within the pre-cooling line 19. Conversely, at the end of the pre-cooling step, that is to say when the first heat exchanger 6 approaches its operating temperature of - 140 °C, there is no vaporization within the first heat exchanger 6 and the gas which circulates in the pre-cooling line 19 is therefore in the liquid state.

[0095] In parallel with the pre-cooling step, the supply method implements the cooling step, which allows the second pump 10 to be brought up to temperature. This cooling step has, similarly to the pre-cooling step, a sub-step of sampling gas in the liquid state in the tank 8 during which gas in the liquid state is sampled from the tank 8 using for example the first pump 9 and then circulates within the first supply circuit 2 to the second pump 10. The cooling step subsequently comprises a sub-step of cooling the second pump 10, which corresponds to the gas in the liquid state passing through said second pump 10. The cooling step ends with a sub-step of circulation of the gas having cooled the second pump 10 within the cooling line 28, such circulation being permitted because the control valve is in its fully open configuration.

[0096] In the same way as for the pre-cooling step, during the cooling step the sub-steps of sampling, cooling and circulation are implemented simultaneously and repeated until a desired temperature is obtained for the second pump 10. The time necessary to obtain such a temperature setting of the first heat exchanger 6 and the second pump 10 is for example one hour, such a duration being improved here thanks to the increase in flow rate within the first heat exchanger 6 that the pre-cooling system 17 allows, thus equalizing the cooling durations of the first heat exchanger 6 and the second pump 10.

[0097] Once the first heat exchanger 6 has been brought to its operating temperature, the pre-cooling step is completed by the control valve 21 changing from its open configuration to its closed configuration. In the same way, the cooling step of the second pump 10 is completed by the control valve 29 changing from its fully open configuration to its partially open configuration, which is compatible with a normal operating pressure of the high-pressure gas-consuming appliance 4.

[0098] The implementation of the feeding step of the feeding method is then possible. During this feeding step, gas in the liquid state is taken from the tank 8 and circulates within the first feeding circuit 2 so as to successively pass through the first heat exchanger 6, the second pump 10, the second heat exchanger 7 and the high pressure evaporator 11 in accordance with what has been described previously in order to be conveyed to the high pressure gas consuming device 4 to supply it.

[0099] Notably, in the particular case of the second embodiment, the pre-cooling step and the supply step are implemented simultaneously. During the supply method according to this second embodiment, during the sampling sub-step of the pre-cooling step, at least a portion of the gas in the liquid state taken from the tank 8 is diverted from the first heat exchanger 6 by circulating via the bypass line 33 in order to be conveyed to the high-pressure gas-consuming device. In this case, contrary to what has been described above, the regulating member 34 is open and the second valve 36 is closed.

[0100] The present invention thus proposes a gas supply system in which the heating of a heat exchanger is carried out independently of the heating of other components, the time required for this heating being reduced by increasing the flow rate of gas circulating within the heat exchanger.

[0101] The present invention cannot, however, be limited to the means and configurations described and illustrated here and it also extends to any equivalent means and configuration as well as to any technically operative combination of such means.

Claims

Claims

1. A gas supply system (1) for at least one high-pressure gas-consuming device (4) and at least one low-pressure gas-consuming device (5) of a floating structure (20) comprising at least one tank (8) configured to contain the gas, the supply system (1) comprising: - at least one first gas supply circuit (2) for the high-pressure gas-consuming device (4), comprising at least one first pump (9) configured to pump the gas taken in the liquid state from the tank (8), at least one first heat exchanger (6), a second heat exchanger (7), a second pump (10) arranged between the first heat exchanger (6) and the second heat exchanger (7) and at least one high-pressure evaporator (11) configured to evaporate the gas circulating in the first gas supply circuit (2);- at least one second gas supply circuit (3) for the low-pressure gas-consuming device (5), comprising at least one compressor (13) configured to compress gas taken in the vapor state from the tank (8) to an operating pressure of the low-pressure gas-consuming device (5), characterized in that the supply system (1) comprises a pre-cooling system (17) for the first heat exchanger (6) configured to take gas in the liquid state from the tank (8), the pre-cooling system (17) comprising a pre-cooling line (19) connected to the first supply circuit (2) between the first heat exchanger (6) and the second pump (10), the pre-cooling system (17) comprising at least one regulating valve (21) for the circulation of the gas within the pre-cooling line (19).;

2. A supply system (1) according to claim 1, wherein the first supply circuit (2) comprises a first valve (35) arranged between the first pump (9) and the first heat exchanger (6) and a second valve (36) arranged between the first heat exchanger (6) and the second pump (10), the pre-cooling line (19) being connected to the first supply circuit (2) between the first heat exchanger (6) and the second valve (36).

3. A power supply system (1) according to any one of claims 1 and 2, wherein the pre-cooling system (17) is configured so that the pre-cooling line (19) opens into a lower portion of the tank (8).

4. Feeding system (1) according to any one of claims 1 and 2, wherein the pre-cooling system (17) is configured so that the pre-cooling line (19) opens into an upper portion of the tank (8).

5. A feed system (1) according to any one of claims 1 to 4, comprising a gas return line (14) connected to the second feed circuit (3) and configured to return the gas to the tank (8), the first heat exchanger (6) and the second heat exchanger (7) each comprising a first pass constituting the first feed circuit (2) and a second pass constituting the return line (14).

6. A feed system (1) according to claim 5, wherein the pre-cooling line (19) is connected to the return line (14) between the first heat exchanger (6) and an outlet of the return line (14) configured to open into the tank (8).

7. Supply system (1) according to any one of claims 1 to 6, comprising a cooling system (24) for the second pump (10), the cooling system (24) comprising a cooling line (28) connected to the first supply circuit (2) between an inlet port of the second pump (10) and the second heat exchanger (7), the cooling system (24) comprising at least one control valve (29) for the circulation of the gas within the cooling line (28).

8. Feeding system (1) according to claim 7, wherein the cooling system (24) is configured so that the cooling line (28) opens into the tank (8).

9. Feeding system (1) according to claim 7 in combination with claim 5, wherein the cooling line (28) opens into the return line (14) between the first heat exchanger (6) and the outlet of the return line (14) configured to open into the tank (8).

10. A supply system (1) according to any one of claims 1 to 9 in combination with claim 5, wherein the return line (14) comprises an expansion member (15) disposed between the first heat exchanger (6) and an outlet of the return line (14). configured to open into the tank (8).

11. Supply system (1) according to any one of claims 1 to 10, comprising a bypass line (33) of the first heat exchanger (6), this bypass line (33) comprising a regulating member (34).

12. Floating structure (20) for storing and / or transporting gas in the liquid state, comprising at least one tank (8) configured to contain gas in the liquid state, at least one high-pressure gas-consuming device (4), at least one low-pressure gas-consuming device (5) and at least one system (1) for supplying gas to these consuming devices (4, 5) according to any one of claims 1 to 11.

13. System for loading or unloading liquid gas which combines at least one onshore and / or port installation (27) and at least one floating structure (20) for storing and / or transporting liquid gas according to the preceding claim.

14. Method for loading or unloading a liquid gas from a floating structure (20) for storing and / or transporting gas according to claim 12, in which pipelines (23) for loading and / or unloading gas in the liquid state arranged on an upper deck of the floating structure (20) can be connected, by means of suitable connectors, to a maritime or port terminal in order to transfer the gas in the liquid state from or to the tank (8).

15. Method for supplying a floating structure (20) according to claim 12 by a supply system (1), comprising at least one preliminary pre-cooling step comprising a sub-step of sampling gas in the liquid state in the tank (8), a sub-step of cooling the first heat exchanger (6) and a sub-step of circulating the gas within the pre-cooling line (19), the supply method comprising a step of supplying the high-pressure gas-consuming apparatus (4) with gas in the liquid state taken from the tank (8).

16. A feeding method according to claim 15, wherein during the pre-cooling step the control valve (21) of the pre-cooling system (17) is open.

17. Feeding method according to any one of claims 15 and 16, comprising at least one step of cooling prior to the feeding step, comprising a sub-step of sampling gas at the liquid state in the tank (8), a sub-step of cooling the second pump (10) and a sub-step of circulation of the gas within the cooling line (28).

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