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 appliances. The present invention relates to a gas supply system (1) for a high pressure gas-consuming appliance (4) of a floating structure (20) comprising at least one tank (8), comprising: - at least one first supply circuit (2) for the high pressure gas-consuming appliance (4), comprising a first heat exchanger (6), a second heat exchanger (7), and a pump (10); characterized in that the supply system (1) comprises a pre-cooling system (17) for the first heat exchanger (6) configured to draw gas in liquid form from the tank (8), the pre-cooling system (17) comprising a pre-cooling line (19) and a regulating valve (21) for 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 ships for the storage and / or transport of gas in liquid form and more particularly concerns a gas supply system for consuming appliances included within such ships.

[0002] During a voyage undertaken by a vessel carrying a tank of liquid gas intended for consumption and / or delivery to a destination, said vessel may be capable of using at least some of said liquid gas to power at least one of its engines, via a gas supply system. This is the case for vessels equipped with an ME-GI type propulsion engine. In order to power this type of engine, the gas must be compressed to very high pressure by special compressors capable of compressing the gas up to 300 bar, but such compressors are expensive, generate significant maintenance costs, and induce vibrations within the vessel.

[0003] An alternative to installing these high-pressure compressors is to vaporize the gas in liquid form at 300 bar before it is sent to the propulsion engine. Since this solution does not eliminate the gas in vapor form (or BOG, which stands for "boil-off gas") that naturally forms 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 at which the engines can be supplied with gas. The size of the components that need to be brought to temperature is likely to affect the time required for such pre-cooling; thus, preparing 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 bring large components, such as a heat exchanger, up to temperature is reduced so as to accelerate the time of starting up the gas supply system.

[0006] The main object of the present invention is therefore a gas supply system of at least one high-pressure gas-consuming appliance and at least one low-pressure gas-consuming appliance of a floating structure comprising at least one tank configured to contain the gas, the supply system comprising: at least one first gas supply circuit for the high-pressure gas-consuming appliance, comprising at least one first pump configured to pump the gas taken in liquid form from the tank, at least one first heat exchanger, a second heat exchanger, a second pump disposed 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 appliance, comprising at least one compressor configured to compress gas drawn in vapor form from the tank to an operating pressure of the low-pressure gas-consuming appliance. According to the invention, the supply system comprises a pre-cooling system for the first heat exchanger configured to draw gas in liquid form 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 gas circulation 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 appliances. More specifically, the first gas supply circuit provides the fuel requirements of the high-pressure gas consuming appliance. This appliance may, for example, be the means of propulsion for the floating structure, such as an ME-GI engine. The first supply circuit extends from the tank to the high-pressure gas consuming appliance. The first pump is installed at the bottom of the tank and pumps the gas in its liquid state so that it can circulate in the first supply circuit.

[0008] Since the gas must be in a vapor state 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 a heat exchange between the gas in a liquid state circulating in the first supply circuit and a heat transfer fluid, for example, glycol water, seawater, or steam. The latter must be at a sufficiently high temperature to induce a change of state in the gas so that it transitions to a vapor or supercritical state in order to supply the high-pressure gas-consuming device.

[0009] Before the liquid gas circulating in the first supply circuit is vaporized by the high-pressure evaporator, the liquid gas passes through the first heat exchanger and then the second heat exchanger. To achieve this, the first and second heat exchangers are connected by a portion of the first supply circuit so that the liquid gas can pass through both heat exchangers sequentially. The temperature of the liquid gas thus tends to increase before it passes through the high-pressure evaporator. Consequently, 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, the gas contained in the tank can naturally, or be forced by the floating structure, into a vapor state. The gas within the tank that vaporizes must be vented to prevent overpressure within the tank. This function is performed by the second gas supply circuit of the low-pressure gas-consuming device. This 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 located on the second supply circuit is responsible for drawing in the gas present in the tank head in order to both supply the low-pressure gas-consuming device and regulate the pressure within the tank. At the compressor outlet, the gas in a 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 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 increases the pressure of the liquid gas circulating in the first supply circuit so that it has a pressure suitable for supplying the high-pressure gas-consuming device.

[0012] The supply system includes a pre-cooling system for the first heat exchanger, which is used to bring this first heat exchanger to the required temperature during a preparation or pre-cooling stage of the floating structure. During the preparation stage, the temperature of the first heat exchanger is, for example, lowered to approximately -140 °C. Such a preparation stage is usually carried out when the floating structure is docked, prior to supplying its consuming equipment. For this purpose, the supply system is configured to draw gas in liquid form from the tank, if necessary by circulating it through a portion of the first supply circuit extending between the The first pump and the first heat exchanger are connected to the first supply circuit. The supply system includes 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. This line serves to vent the pre-cooled gas from the first heat exchanger. The flow of gas within this pre-cooling line is controlled by the pre-cooling system's control valve. This control valve has an open and a closed configuration; gas flow in the pre-cooling line is permitted when the control valve is open. The presence of the pre-cooling circuit allows the first heat exchanger to be pre-cooled independently of the second pump.

[0013] The pre-cooling system lowers the temperature of the first heat exchanger before it operates within the supply system. To achieve this, the pre-cooling system increases the gas flow rate through the first heat exchanger, thereby accelerating the time required for it to reach operating temperature. For example, the pre-cooling system doubles or triples the gas flow rate circulating within the first heat exchanger compared to the gas flow rate typically used when the first heat exchanger is operating to supply the high-pressure gas-consuming appliance.Thus, the time required to prepare the entire power system is reduced, as the first heat exchanger can be brought up to temperature in a similar time frame to the time required to bring other, less substantial components of the power system, such as the second pump, up to temperature.

[0014] According to an optional feature of the invention, the first supply circuit includes a first valve disposed between the first pump and the first heat exchanger and a second valve disposed 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 and second valves form a bypass circuit for the first heat exchanger. This bypass circuit, in conjunction with the pre-cooling system, allows, in particular, for purging the first pass of the heat exchanger, which is located between these two valves. In this 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. Furthermore, the bypass circuit allows for maintenance operations to be performed on the first heat exchanger.

[0016] According to an optional feature 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 feature 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 storing gas in its liquid state and an upper portion dedicated to storing gas evaporated from the gas in its liquid state, the lower portion corresponding to the tank bottom and the upper portion corresponding to the tank top. The pre-cooling line can, according to various embodiments, terminate either at the tank bottom or at the tank top. In both cases, the pre-cooling line terminates directly in the tank; that is, it is not connected to any other supply system line for the purpose of terminating in the tank.

[0019] According to an optional feature of the invention, the supply system includes 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 and second heat exchangers are each configured to perform a heat exchange between the gas circulating in the return line in vapor form and the gas in liquid form circulating in the first supply circuit. This return line is located between the compressor and the low-pressure gas-consuming device and extends to the tank. At the compressor outlet, the gas in vapor form flows through the return line if the low-pressure gas-consuming device does not require a fuel supply. The gas in vapor form circulating in the return line first passes through the second heat exchanger, then the first heat exchanger, before returning to the tank.Thanks to the heat exchange occurring between the liquid gas circulating in the first supply circuit and the vapor gas circulating in the return line, the temperature of the vapor gas decreases as it passes through the heat exchangers, until the gas condenses and returns to a liquid state approximately at the outlet of the first heat exchanger. The recondensed gas then flows back to the tank. The first heat exchanger is configured to condense the gas circulating in the return line. The first heat exchanger is the exchanger through which the liquid gas of the first supply circuit passes when said liquid gas is at its lowest temperature. Therefore, the heat exchange takes place within the first heat exchanger, which changes the state of the gas circulating in the return line from vapor to liquid. The second heat exchanger is configured to pre-cool the gas circulating in the return line before it passes through the first heat exchanger.

[0021] According to an optional feature 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 avoids the need to manufacture and install a dedicated section of line all the way to the tank.

[0023] According to an optional feature of the invention, the supply system includes a cooling system for the second pump, the cooling system including 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 including at least one gas circulation control valve within the cooling line.

[0024] The cooling system for the second pump is the counterpart to the pre-cooling system for the first heat exchanger. The cooling system for the second pump is thus used during the preparation stage of the supply system to lower the temperature of the second pump before it operates within the supply system. To this end, the cooling system draws gas in its liquid state and increases the flow rate of this liquid gas through the second pump, thereby bringing it to the required 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 circumstances, 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 feature 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. Depending on the embodiment, the cooling line may terminate at the bottom of the tank or in the tank ceiling.

[0028] According to an optional feature 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 from the inlet port of the second pump to the outlet of the second pass of the first heat exchanger. After pre-cooling the second pump, the gas in its liquid state circulates within the cooling line and then follows the return line to be conveyed to the tank. This configuration eliminates the need to manufacture and install a dedicated section of line 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 device such as a bubbling device. This allows at least a portion of the gas in vapor form to be liquefied as it returns to the tank, also resulting in a temperature increase of the gas in liquid form present in the tank.

[0031] According to an optional feature of the invention, the return line includes a pressure-reducing element disposed between the first heat exchanger and an outlet of the return line configured to open into the tank.

[0032] The expansion valve reduces the pressure of the gas circulating in the return line after it has condensed during its passage through the first heat exchanger. Thanks to the expansion valve, the gas in its liquid state is returned to the tank at a temperature close to the gas's liquid-vapor equilibrium temperature. The expansion valve also regulates the flow rate of the gas to be condensed circulating in the return line. When one or both of the pre-cooling and / or cooling lines terminate in the return line, they are connected between this expansion valve and the return line outlet; that is, they are connected downstream of the expansion valve.

[0033] According to an optional feature of the invention, the supply system includes a bypass line of the first heat exchanger, this bypass line including a regulating element.

[0034] This bypass line and the regulating element which it carries together form the bypass system of the first pass of the first heat exchanger.

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

[0036] The invention also covers a system for loading or unloading a liquid gas which combines at least one onshore and / or port installation and at least one floating structure for the storage and / or transport of liquid gas as mentioned above.

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

[0038] The invention finally relates to a method of supplying a floating structure as previously mentioned by a supply system as previously mentioned, comprising at least one prior pre-cooling stage including a sub-stage of taking gas in liquid state from the tank, a sub-stage of cooling the first heat exchanger and a sub-stage of circulating the gas within the pre-cooling line, the supply method comprising a stage of supplying the high-pressure gas-consuming device with gas in 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 allows the first heat exchanger to be brought to temperature to allow such a supply of the high-pressure gas-consuming device, and also allows, subsequently, the condensation of the gas circulating within the return line.

[0040] According to an optional feature of the invention, during the pre-cooling stage the control valve of the pre-cooling system is opened.

[0041] Opening this regulating valve allows the gas to use the pre-cooling line.

[0042] According to an optional feature of the invention, the feeding process includes at least one pre-feeding cooling step, comprising a sub-step of drawing gas in liquid state from 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 its liquid state circulates either within the first heat exchanger, and more specifically 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 features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and examples of embodiment on the other. given for illustrative purposes only and not as an exhaustive list, with reference to the attached drawings, on which:

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

[0046] [Fig.2] illustrates, schematically, the gas supply system of the [Fig.1] according to a second embodiment;

[0047] [Fig.3] illustrates, schematically, the gas supply system of the [Fig.1] according to a third embodiment;

[0048] [Fig.4] illustrates, schematically, the gas supply system of the [Fig.1] according to a fourth embodiment;

[0049] [Fig.5] illustrates, schematically, the gas supply system of the [Fig.1] according to a fifth embodiment;

[0050] [Fig.6] schematically illustrates 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 can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, 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, elements common to several figures retain the same reference. The terms "upstream" and "downstream" used in the following description are used to express the positions of components within circuits of gases in the liquid or vapor state and refer to the direction of flow of said gas within said circuit.

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

[0054] Said floating structure may, for example, be a vessel capable of storing and / or transporting gas in liquid form. The supply system 1 is in this case capable of using the gas in liquid form that the floating structure stores and / or transports to supply the high-pressure gas-consuming device 4, which may by example be 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] 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 includes a first pump 9 located within the tank 8. The first pump 9 pumps the gas in its liquid state and circulates it, in particular, within the first supply circuit 2. By drawing in the gas in its liquid state, the first pump 9 also increases its pressure to a value between 6 and 17 bar.

[0056] The gas in liquid form, in a direction of flow 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 liquid form to a value between 30 and 70 bar for use with liquefied petroleum gas, and preferably between 150 and 400 bar for use with ethane, ethylene or liquefied natural gas consisting mainly of methane.

[0057] Following passage through the second heat exchanger 7, the gas flows to a high-pressure evaporator 11. The high-pressure evaporator 11 modifies the state of the gas circulating in the first supply circuit 2, changing it to a vapor or supercritical state. This state allows the gas to be compatible for supplying the high-pressure gas-consuming device 4. The evaporation of the gas into a liquid state can, for example, be achieved by heat exchange with a heat transfer fluid at a sufficiently high temperature to evaporate the gas into a liquid state, in this case glycol water, seawater, or steam.

[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 tank 8, a portion of the gas cargo can naturally vaporize and diffuse into a tank head 12, which corresponds to an upper part of tank 8, as opposed to a tank bottom 16, which corresponds to a lower part. To prevent overpressure within tank 8, the vaporized gas contained in the tank head 12 must be vented. However, the first supply circuit 2 is configured to use the gas in its liquid state to supply the high-pressure gas-consuming device 4.

[0060] The supply system 1 includes a second gas supply circuit 3, which uses gas in its vapor state to supply the low-pressure gas-consuming device 5. The second supply circuit 3 therefore extends between the tank head 12 and the low-pressure gas-consuming device 5. In order to draw the gas in its vapor state from the tank head 12, the second supply circuit 3 includes a compressor 13. In addition to drawing the gas in its vapor state, the compressor 13 also increases the pressure of the gas in its vapor state circulating in the second supply circuit 3 to a pressure between 6 and 20 bar absolute, so that the gas in its vapor state is at a pressure suitable for supplying the low-pressure gas-consuming device 5. The second supply circuit 3 thus supplies the low-pressure gas-consuming device 5 while regulating the pressure within the tank 8 by drawing the gas in its vapor state from the tank head 12.

[0061] The presence of an excessive amount of gas in vapor form within the tank head 12 causes overpressure within the tank 8. It is therefore necessary to evacuate the gas in vapor form in order to lower the pressure within the tank 8. The excess gas in vapor form can then, for example, be eliminated by a burner 18. However, the supply system 1 according to the invention includes 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 with respect to a direction of flow of the gas in the vapor state circulating in the second supply circuit 3. According to the direction of flow of the gas in the vapor state circulating in the return line 14, said gas passes through the second heat exchanger 7 first, then passes through the first heat exchanger 6. The heat exchange 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 changes to a liquid state and returns to the tank 8 in that state, instead of being eliminated by the burner 18. More precisely, the gas flowing in the return line 14 is in a vapor state at the inlet of the first heat exchanger 6 and exits in a 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 feed circuit 2 as well as a second pass constituting the return line 14.

[0064] In order to align the pressure of the gas flowing in the return line 14 with the pressure in the tank 8, the return line 14 may include a pressure-reducing device 15, positioned between the first heat exchanger 6 and an outlet of the return line 14 leading to the tank 8, the gas pressure is reduced to between 1 and 3 bar absolute. Once the gas is condensed in the first heat exchanger 6 and then expanded in the expansion device 15, it continues its path to the outlet of the return line 14, i.e., 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 along the direction of gas flow in the first supply circuit 2, and upstream of the first heat exchanger 6 along the direction of gas flow in the return line 14. The second heat exchanger 7 therefore provides preliminary cooling of the gas in its vapor state circulating in the return line 14 before it is condensed in the first heat exchanger 6; in other words, the second heat exchanger 7 is a pre-cooler. In the first supply circuit 2, the gas in its 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 therefore possible that, following the heat exchange occurring at the second heat exchanger 7, the gas circulating within the first supply circuit 2 exits the second heat exchanger 7 in a two-phase state. The temperature of the gas circulating in the return line 14 is thus lowered after passing through the second heat exchanger 7, implementing the pre-cooling mentioned above in relation to the second heat exchanger 7.

[0066] It should be noted that in order to optimally and promptly perform its function as a condenser of 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 of feeding the floating structure 20, is a prerequisite to implementing 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 includes a pre-cooling system 17 of 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 includes a pre-cooling line 19 which is connected differently within the supply system 1 depending on the embodiment, as well as a regulating valve 21 for the gas circulation 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 draw gas in liquid form from the tank 8, if necessary using the first pump 9, and to convey it to the first heat exchanger 6. The gas in liquid form is conveyed to the first heat exchanger 6 via a line of the first supply circuit 2 connecting the tank 8 to the first heat exchanger 6. This line therefore contributes both to supplying the high-pressure gas-consuming device 4 and to pre-cooling the first heat exchanger 6. The first heat exchanger 6 is pre-cooled when it is traversed by the gas in liquid form; it is thus understood that the greater the flow rate of gas in liquid form passing through the first heat exchanger 6, the more rapidly the temperature of this first heat exchanger 6 will be lowered.

[0070] In addition to the pre-cooling system 17, the supply system 1 includes a cooling system 24 for the second pump 10; this cooling system 24 allows, during a step prior to supplying the high-pressure gas-consuming device 4, the circulation of gas in a 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 draw gas in liquid form from the tank 8, if necessary using the first pump 9, and to convey it to the second pump 10. The gas in liquid form is conveyed to the second pump 10 in particular via the first supply circuit line 2 which connects the tank 8 to the first heat exchanger 6. This line therefore participates both in supplying the high-pressure gas-consuming device 4, in pre-cooling the first heat exchanger 6 and in cooling 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 In its closed configuration, the passage of gas in a liquid state within the cooling line 28 is prevented. Conversely, during the cooling of the second pump 10, 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 Figures 1 to 4, the cooling line 28 extends more precisely to the upper portion of the tank 8, that is to say, it opens into the tank head 12. However, without departing from the scope of the invention, alternative embodiments could be considered in which the cooling line 28 opens into the bottom of the tank 16. It should be noted that the control valve 29, which regulates the passage of gas within the cooling line 28, has a function of reducing the gas to a liquid state.Thus, the gas in liquid state circulating in the cooling line 28 has a pressure of around 9 bars between the second pump 10 and the control valve 29, i.e. upstream of this control valve 29, and a pressure of less than 2 bars, i.e. close to that of the gas in liquid state in the tank 8, between the control valve 29 and the tank 8, i.e. 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 includes 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 to 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 of gas circulating within the first heat exchanger 6 without impacting the flow of gas which is sent to the second pump 10, a surplus of gas flow being diverted into the pre-cooling line 19. .

[0076] In the first and second embodiments, illustrated in Figures 1 and 2 respectively, 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. 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, i.e., it terminates in the tank head 12. As specified for the cooling line 28, alternative embodiments could be considered in which the pre-cooling line 19 terminates in the bottom of the tank. 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 includes a bypass line 33 arranged in parallel with the first pass of the first heat exchanger 6, as well as a control element 34 carried by said bypass line 33.

[0078] The bypass circuit 32 prevents gas from passing through the first heat exchanger 6, particularly for purging purposes, for example during maintenance of said first heat exchanger 6. To achieve this, the bypass circuit 32 is used in conjunction with valves located on the first supply circuit 2 on either side of the first heat exchanger 6, specifically a first valve 35 located upstream of the heat exchanger 6 and a second valve 36 located downstream of it. 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 parallel to 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 are part of a portion of the first supply circuit 2 which the bypass circuit 32 allows to be avoided.

[0079] The control device 34, when open, allows the passage of gas in a liquid state within the bypass line 33. The first valve 35 allows the passage of gas in a liquid state within the first pass of the first heat exchanger 6 when open and prevents such passage when closed. The second valve 35 allows the gas to circulate to the second pump 10 and, by extension, to the high-pressure gas-consuming device 4 when open and prevents such passage when closed. It follows from the above that the purging of the first heat exchanger 6 is carried out when the control device 34 is open, the first valve 35 is closed, and when the pre-cooling system 17 is operating, i.e., when the control valve 21 is in its open position.

[0080] It should be noted that the bypass circuit 32 can also be used when the first heat exchanger 6 has excessively high temperatures which could cause the gas circulating within it to vaporize, thereby potentially damaging the second pump 10 which would then be supplied with gas in a vapor state rather than gas in a vapor state liquid. The bypass circuit 32 allows, 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 a liquid state so as to allow its optimal operation.

[0081] Furthermore, thanks to the second embodiment of [Fig. 2], it is possible to simultaneously supply the high-pressure gas-consuming device 4 and pre-cool the first heat exchanger 6. In this case, the control element 34 is open, so that gas in a liquid state can flow in the bypass line 33 and then back into the first supply circuit 2 to the high-pressure gas-consuming device 4. The second valve 36 is closed to prevent backflow of gas to the first heat exchanger 6. In parallel, the first valve 35 is open, so that a portion of gas in a liquid state from the tank 8 passes through the first heat exchanger 6 before flowing into the pre-cooling line 19. To achieve this, the control valve 21 of this pre-cooling line 19 is in its open configuration.Mixing of the gas that has passed through the first heat exchanger 6 and the gas that has 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 notably allows the floating structure to start up simultaneously with the heating of the first heat exchanger 6.

[0082] The third embodiment, illustrated in [Fig. 3], differs from the first embodiment of [Fig. 1] in that the pre-cooling line 19 is not directly connected 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, 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 specifically, 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. Where appropriate, the outlet of the return line 14 may be equipped with an ejection member such as a bubbling member, not shown here. In this fourth embodiment, as previously mentioned, the cooling line 28 opens into the tank 8.

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

[0085] It should be noted that, provided 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 showing the tank 8 containing the gas in liquid and vapor states, this tank 8 being generally prismatic in shape mounted in a double hull 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 liquid state contained in the tank 8, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 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 hull 22.

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

[0088] Figure 6 also shows an example of a marine or port terminal comprising loading and / or unloading equipment 25, a subsea pipeline 26, and an onshore and / or port facility 27. The onshore and / or port facility 27 may, for example, be arranged on a port quay, or, in another example, be arranged on a concrete gravity platform. The onshore and / or port facility 27 includes liquid gas storage tanks 30 and connecting pipelines 31 linked by the subsea pipeline 26 to the loading and / or unloading equipment 25.

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

[0090] A method for 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 the preparation of the supply system 1 and a second part which is the supply as such to one and / or the other of the consuming devices 4, 5.

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

[0092] The pre-cooling step allows the first heat exchanger 6 to reach the required temperature. This pre-cooling step begins with a sub-step of drawing liquid gas from tank 8, during which liquid gas is drawn from 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 includes a sub-step of cooling the first heat exchanger 6, which corresponds to the circulation of the liquid gas through the heat exchanger 6. The gas is then discharged from the first heat exchanger 6 and circulates in the pre-cooling line 19 for its return to tank 8 during a circulation sub-step. For this purpose, the control valve 21 is in its open position.The gas is returned to 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 stage according to the first, third, fourth and fifth embodiments, the bypass circuit 32 is not used, so the regulating element 34 is closed. Conversely, the first valve 35 and the second valve 36 are both open.

[0094] The sampling, pre-cooling, and circulation substeps are carried out continuously and simultaneously until a temperature of -140 °C is reached in the first heat exchanger 6. The time required to reach such a temperature is, for example, one hour, a duration that is improved here by the increased flow rate within the first heat exchanger 6 made possible by the pre-cooling system 17. It should be noted that at the beginning of the pre-cooling step, the first heat exchanger 6 has a particular temperature lye elevated; 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 stage, that is to say when the first heat exchanger 6 is approaching 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 feeding process implements the cooling step, which allows the second pump 10 to be brought to temperature. This cooling step has, similarly to the pre-cooling step, a sub-step of drawing gas in liquid state from the tank 8 during which gas in liquid state is drawn 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 includes a sub-step of cooling the second pump 10, which corresponds to a passage through said second pump 10 by the gas in liquid state. The cooling stage ends with a sub-stage of circulating the gas that 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 stage, during the cooling stage the sub-stages of sampling, cooling and circulation are implemented simultaneously and repeated until a desired temperature is obtained for the second pump 10. The time required to obtain such a temperature of the first heat exchanger 6 and the second pump 10 is for example one hour, such duration being improved here thanks to the increase in flow within the first heat exchanger 6 which the pre-cooling system 17 allows, thus equalizing the cooling times of the first heat exchanger 6 and the second pump 10.

[0097] Once the first heat exchanger 6 has reached its operating temperature, the pre-cooling stage is completed by switching the control valve 21 from its open to its closed position. Similarly, the cooling stage of the second pump 10 is completed by switching the control valve 29 from its fully open to its partially open position, which is compatible with the normal operating pressure of the high-pressure gas-consuming device 4.

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

[0099] Notably, in the specific case of the second embodiment, the pre-cooling and feeding stages are carried out simultaneously. During the feeding process according to this second embodiment, during the sampling substage of the pre-cooling stage, at least a portion of the liquid gas drawn from the tank 8 is diverted from the first heat exchanger 6 by circulating through the bypass line 33 to be conveyed to the high-pressure gas-consuming device. In this case, contrary to what has been described above, the control device 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 is not limited to the means and configurations described and illustrated herein and also extends to any equivalent means and configuration as well as to any technically operative combination of such means.

Claims

Demands

1. Gas supply system (1) for at least one high-pressure gas-consuming appliance (4) and at least one low-pressure gas-consuming appliance (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 appliance (4), comprising at least one first pump (9) configured to pump the gas taken in liquid form from the tank (8), at least one first heat exchanger (6), a second heat exchanger (7), a second pump (10) disposed 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 vapor form 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 liquid form 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. Supply system (1) according to claim 1, wherein the first supply circuit (2) comprises a first valve (35) disposed between the first pump (9) and the first heat exchanger (6) and a second valve (36) disposed 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. Power supply system (1) according to any one of claims 1 and 2, in which 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. Supply system (1) according to any one of claims 1 to 4, comprising a gas return line (14) connected to the second supply 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 supply circuit (2) and a second pass constituting the return line (14).

6. Feeding 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 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 a pressure-reducing element (15) disposed between the first heat exchanger (6) and an outlet of the return line (14) configured to open into the tank (8).

11. Power 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 element (34).

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

13. System for loading or unloading a liquefied gas which combines at least one onshore and / or port facility (27) and at least one floating structure (20) for the storage and / or transport of liquefied gas according to the preceding claim.

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

15. Method of supplying a floating structure (20) according to claim 12 by a supply system (1), comprising at least one preliminary pre-cooling step including a sub-step of drawing gas in liquid state from 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 device (4) with gas in liquid state drawn from the tank (8).

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

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

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