Gas supply system for high and low pressure gas consuming devices

Abstract

The invention relates to a gas supply system (1) for high pressure gas consuming appliances (4) and low pressure gas consuming appliances (5) of a floating structure comprising a tank (8) containing gas, said supply system (1) comprising a first supply circuit (2) and a second supply circuit (3), characterized in that said supply system (1) comprises a gas return line (14), said supply system (1) comprises a first heat exchanger (6) and a second heat exchanger (7), the second heat exchanger (7) being configured to exchange heat between the gas of the first supply circuit (2) and the gas circulating in the return line (14), the first supply circuit (2) comprising an additional pump (10).

Description

Technical Field

[0001] This invention relates to the field of liquid gas storage and / or transport vessels, and more particularly, to gas supply systems for consumable equipment included in such vessels. Background Technology

[0002] During a journey undertaken by a vessel that includes tanks for consuming and / or transporting liquid gas to its destination, the vessel is able to use at least a portion of the liquid gas to supply at least one of its engines via a gas supply system. This is the case for vessels equipped with ME-GI type propulsion engines. To supply this type of engine, the gas must be compressed to very high pressures by a special compressor capable of compressing the gas to 300 bar, but such compressors are expensive, increase maintenance costs considerably, and cause vibrations within the vessel.

[0003] An alternative to installing these high-pressure compressors is to vaporize the liquid gas at a pressure of 300 bar before delivering it to the propulsion engine. This solution cannot eliminate the gas in vapor form (or BOG, meaning "vaporized gas") that naturally forms in the tanks that at least partially contain the cargo. Low-pressure compressors can be installed to supply gas to the auxiliary engine, which can consume the gas in low-pressure vapor form. On the other hand, in this configuration, if the amount of vapor form present is too large, or more generally, greater than the amount required for consumption by the auxiliary engine, the unconsumed vapor form accumulates under pressure in the tanks within certain limits, and is then eliminated by combustion, or as a last resort, by releasing it into the atmosphere. This type of elimination results in fuel waste and harmful environmental consequences. Summary of the Invention

[0004] This invention eliminates this loss by providing a gas supply system for at least one high-pressure gas consuming device and at least one low-pressure gas consuming device for a floating structure. The system includes at least one tank configured to contain gas, and the supply system comprises:

[0005] The high-pressure gas consuming device includes at least one first gas supply circuit, comprising at least one pump configured to pump liquid gas collected in a tank.

[0006] At least one high-pressure evaporator is configured to evaporate the gas flowing in the first gas supply circuit.

[0007] At least one second circuit for supplying gas to a low-pressure gas-consuming device includes at least one compressor configured to compress gas extracted in a vapor state from a tank to a pressure appropriate for the requirements of the low-pressure gas-consuming device.

[0008] The system is characterized in that the supply system includes a gas return line connected downstream of the compressor to a second supply loop and extending to a tank, the supply system including at least a first heat exchanger and at least a second heat exchanger, each of the first and second heat exchangers being configured to exchange heat between gas flowing in the gas return line and liquid gas flowing in the first supply loop, the first supply loop including an additional pump disposed between the first and second heat exchangers.

[0009] With this supply system, gaseous gases present in the tank that are not consumed by low-pressure gas-consuming equipment can be condensed and thus returned to the tank in liquid form, rather than being eliminated. This at least reduces the loss of excess vaporized gas present in the tank.

[0010] The first gas supply circuit enables the fuel requirements of the high-pressure gas consumption device to be met. This device may be, for example, a propulsion system for a floating structure, such as a ME-GI engine. The first supply circuit extends from the tank to the high-pressure gas consumption device. A pump is mounted at the bottom of the tank and ensures the pumping of liquid gas, allowing it to flow through the first supply circuit.

[0011] Because the gas must be in a vapor state to be supplied to the high-pressure gas-consuming equipment, the high-pressure evaporator ensures that the gas evaporates before being supplied to the high-pressure gas-consuming equipment. The high-pressure evaporator is the site where heat exchange occurs between the liquid gas flowing in the first supply loop and the heat transfer fluid (such as ethylene glycol water, seawater, or water vapor). This heat transfer fluid must be at a sufficiently high temperature to produce a change in the gas's state, causing it to enter a vapor or supercritical state, thus enabling its supply to the high-pressure gas-consuming equipment.

[0012] Before the liquid flowing in the first supply loop evaporates in the high-pressure evaporator, the liquid gas first passes through the first heat exchanger and then the second heat exchanger. For this purpose, the first and second heat exchangers are connected to each other via a portion of the first supply loop, allowing the liquid gas to pass continuously through both heat exchangers. Therefore, the temperature of the liquid gas tends to rise before it passes through the high-pressure evaporator. Consequently, the gas flowing in the first supply loop can be in a two-phase state at the outlet of the second heat exchanger.

[0013] Generally, the gas contained in the tank can naturally turn into vapor, or be forced into vapor by the floating structure. To avoid overpressure inside the tank, the gas that has turned into vapor must be vented.

[0014] This function is provided by a second gas supply circuit for the low-pressure gas consuming device. This second supply circuit extends from the tank to the low-pressure gas consuming device. The device may be, for example, an auxiliary motor, such as a generator. A compressor arranged on the second supply circuit is responsible for drawing gas from the tank space to supply the low-pressure gas consuming device and for regulating the pressure in the tank.

[0015] At the compressor outlet, vaporized gas can be supplied to low-pressure gas-consuming equipment, or, if the low-pressure gas-consuming equipment does not require fuel intake, it can flow through the return line. Since the return line is connected downstream of the compressor, the vaporized gas drawn in by the compressor can flow through it.

[0016] The vaporized gas flowing in the return line passes through a second heat exchanger and then a first heat exchanger before returning to the tank. Due to heat exchange between the liquid gas flowing in the first supply loop and the vaporized gas flowing in the return line, the temperature of the vaporized gas decreases as it passes through the two heat exchangers until it condenses and essentially returns to a liquid state upon leaving the first heat exchanger. The recondensed gas then flows to the tank.

[0017] In one example, the first and second heat exchangers are located upstream of the high-pressure evaporator along the first supply loop. This ensures that the gas remains liquid in the portions of the first supply loop located within the first and second heat exchangers.

[0018] According to one feature of the invention, the first heat exchanger, the second heat exchanger, and the high-pressure evaporator are physically independent heat exchangers.

[0019] The additional pump allows for an increase in the pressure of the liquid gas flowing in the first supply circuit, enabling it to supply pressure compatible with high-pressure gas-consuming equipment.

[0020] It is particularly advantageous to place an auxiliary pump between the two heat exchangers. In fact, placing an auxiliary pump upstream of the first heat exchanger would cause the pressure and temperature of the liquid gas to increase as it passes through the first heat exchanger, which is detrimental to the condensation of the gaseous gas flowing through the first heat exchanger in the return line. Furthermore, since the gas flowing in the first supply loop may be in a two-phase state at the outlet of the second heat exchanger, placing an auxiliary pump downstream of the second heat exchanger could adversely affect its proper operation, as the auxiliary pump is only permitted to pump liquid fluids. Therefore, the optimal arrangement is to place the pump between the two heat exchangers.

[0021] According to one feature of the invention, the return line may include a branch point dividing the return line into a first section and a second section, both of which extend from the branch point to the tank. A first heat exchanger is configured to exchange heat between gas flowing in a vapor state in the first section of the return line and gas flowing in a liquid state in the first supply loop, while the second section bypasses the first heat exchanger. Dividing the return line into two distinct sections corresponds to a second embodiment of the supply system according to the invention, while the first embodiment corresponds to the supply system as described above, i.e., the return line has no branch point or is divided into two sections.

[0022] According to the second embodiment, gaseous gas present in the tank and not consumed by the low-pressure gas consumption device can be condensed by flowing through the first section of the return line and thus returned to the tank in liquid form instead of being eliminated.

[0023] Furthermore, when the flow rate of liquid gas flowing in the first supply loop is insufficient to condense all the gaseous gas flowing in the return line, the excess gas can be directed to the second section of the return line for direct return to the tank. This occurs when the floating structure equipped with the supply system according to the invention does not require a large amount of liquid gas for propulsion, for example, when the floating structure moves at a reduced speed. Apart from the specific characteristics of the return line described above, the first and second embodiments share the same features.

[0024] The inventors have determined that the gaseous gas flowing in the return line can only be completely condensed if the amount of liquid gas flowing in the first supply circuit is greater than or equal to six times the amount of gaseous gas flowing in the return line. This is applicable when the compressor compresses the gaseous gas to approximately 10 bar, but this ratio can be varied depending on the pressure delivered by the compressor. If this condition is met, the gaseous gas flows in the first section of the return line to be condensed. If the amount of liquid gas flowing in the first supply circuit is less than six times the amount of gaseous gas flowing in the return line, it is advantageous to allow the gaseous gas to flow at least partially in the second section of the return line, and then a portion of the gaseous gas flows in the first section in an amount sufficient for complete condensation.

[0025] The gaseous gas flowing in the return line can flow in either the first or second section from the branch point. The vaporized gas flowing in the return line first passes through a second heat exchanger and then through a first heat exchanger before returning to the tank. With this configuration, the temperature of the gaseous gas decreases as it passes through both heat exchangers due to heat exchange occurring between the liquid gas flowing in the first supply loop and the gaseous gas flowing in the return line, until the gas condenses and returns to a liquid state essentially at the outlet of the first heat exchanger. The condensed gas then flows to the tank. If the gaseous gas flows in the second section, it passes through the second exchanger and then returns directly to the tank. With this configuration, the temperature of the gaseous gas decreases due to heat exchange occurring in the second heat exchanger; however, it is not condensed. Therefore, the gas returns to the tank in a vaporized state but is still cooled.

[0026] According to one feature of the invention, the branch point can be arranged on the return line between the first and second heat exchangers. In other words, the gaseous gas flows in either the first or second section after passing through the second heat exchanger. More specifically, the main section of the return line passes through the second heat exchanger, the main section corresponding to a section of the return line upstream of the branch point relative to the flow direction of the gaseous gas. This feature relates to a second embodiment of the supply system as described above.

[0027] According to one feature of the invention, the branching point can be located on the return line between the second supply loop and the second heat exchanger, with the first and second sections passing through the second heat exchanger. This is a third embodiment of the supply system according to the invention. According to this third embodiment, the branching point is located upstream of the second heat exchanger. The second heat exchanger is configured to perform heat exchange, particularly with the vapor-state gas in the return line, with each of the first and second sections passing through it. Therefore, the second heat exchanger includes at least three channels, that is, two channels for each section of the return line, in addition to the channel through which the liquid gas from the first supply loop flows.

[0028] According to one feature of the invention, the second section of the return line includes a submerged end immersed in the liquid contained in the tank, and the second section includes a jetting member disposed at the submerged end. The jetting member makes it possible, in particular, to expand the gaseous gas flowing in the second section of the return line before the gas is dispersed into the tank. This expansion of the gaseous gas, associated with the fact that the submerged end is preferably located at the bottom of the tank, allows at least a portion of the gaseous gas to liquefy upon its return to the tank, and also results in an increase in the temperature of the liquid gas present in the tank. The jetting member can be, for example, an ejector or a bubbling device.

[0029] According to one feature of the invention, the second section of the return pipeline includes a flow rate regulating member. When the second heat exchanger itself is located downstream of the bifurcation point, the flow rate regulating member can be, for example, a valve located downstream of the second heat exchanger. The flow rate regulating member can also function as an expansion valve. When the second section of the return pipeline is equipped with the injection member as described above, the flow rate regulating member is selected to limit the expansion of the gaseous gas.

[0030] According to one feature of the invention, a first heat exchanger is used to condense the gas flowing in the return line. The first heat exchanger is the exchanger through which the liquid gas in the first supply loop passes when it is at its lowest temperature. Therefore, it is the heat exchange that occurs in the first heat exchanger that changes the state of the gas flowing in the return line from a gaseous state to a liquid state. In the case where the return line is divided into two sections, for example according to the second or third embodiment, only the gas flowing in the first section of the return line is condensed, because the gas flowing in the second section of the return line bypasses the first heat exchanger.

[0031] According to one feature of the invention, the second heat exchanger is configured to pre-cool the gas flowing in the return line. At the outlet of the first heat exchanger, the liquid gas flowing in the first supply loop is less cold than at the inlet of the first heat exchanger, and heat exchange has already been used to condense the vaporized gas in the return line. Subsequently, the liquid gas is compressed by an additional pump and then passes through the second heat exchanger. It also involves heat exchange in the second heat exchanger, allowing pre-cooling of the gaseous gas in the return line. Even if the flow rate of the liquid gas flowing in the first supply loop is insufficient to completely condense the gaseous gas flowing in the return line, cooling still occurs in the second heat exchanger.

[0032] According to one feature of the invention, the return line includes an expansion member disposed downstream of the first heat exchanger. Once the gas is condensed upon passing through the first heat exchanger, the expansion member allows for a reduction in the pressure of the gas flowing in the return line. By means of the expansion member, the liquid gas returns to the tank at a temperature close to the liquid-vapor equilibrium temperature of LNG. The expansion member also serves to regulate the flow rate of the gas to be condensed flowing in the return line. In the case where the return line is divided into two sections, the expansion member is located in the first section of the return line, always downstream of the first heat exchanger.

[0033] According to one feature of the invention, the supply system includes an auxiliary supply line connected upstream of a first heat exchanger to a first supply loop and extending downstream of a compressor to a second supply loop. The supply system also includes a low-pressure evaporator configured to evaporate the gas flowing through the auxiliary supply line. This auxiliary supply line is used when a low-pressure gas consuming device needs to be supplied with gaseous gas, but there is insufficient quantity in the tank space. Therefore, the auxiliary supply line allows a portion of the liquid gas flowing through the first supply loop to be discharged. This portion is then evaporated by the low-pressure evaporator, i.e., through heat exchange with a heat transfer fluid such as water glycol, seawater, or water vapor, similar to operation of a high-pressure evaporator. The low-pressure evaporator thus causes heat exchange between the liquid gas flowing through the auxiliary supply line and the heat transfer fluid.

[0034] Once it becomes vapor, the gas flows through the auxiliary supply line and is then added to the second supply circuit to supply low-pressure gas-consuming equipment.

[0035] If there is a sufficient amount of gaseous gas in the tank space, auxiliary supply lines are not used; for example, they can be shut off via valves.

[0036] According to one feature of the invention, the pump is configured to increase the pressure of the liquid gas to a value between 6 and 17 bar, and the auxiliary pump is configured to increase the pressure of the liquid gas to a value between 30 and 400 bar. This pressure range allows the liquid to be increased to a pressure suitable for each gas-consuming device.

[0037] Additional pumps can increase the pressure of liquid gases to 30 to 400 bar, especially for ammonia or hydrogen, 30 to 70 bar for liquefied petroleum gas, and 150 to 400 bar for ethane, ethylene, or liquefied natural gas which is mainly composed of methane.

[0038] Therefore, with the auxiliary supply line open, the pump installed in the tank increases the pressure of the liquid gas to a pressure that allows it to be supplied to low-pressure gas-consuming equipment.

[0039] The pump enables the pressure of the liquid gas flowing in the first high-pressure supply circuit to be increased to a pressure suitable for supplying high-pressure gas-consuming equipment.

[0040] According to one feature of the invention, the compressor is configured to increase the gas pressure to an absolute pressure value of 6 to 20 bar. This pressure value ensures compatibility between the gaseous gas present in the tank space and drawn into the second supply circuit and the low-pressure gas consumption equipment.

[0041] According to one feature of the invention, the high-pressure evaporator is arranged downstream of the second heat exchanger in the first gas supply circuit of the high-pressure gas consuming device.

[0042] According to one feature of the invention, the second heat exchanger and the high-pressure evaporator constitute a single heat exchanger. The first heat exchanger is separate and arranged upstream of the single heat exchanger that combines the second heat exchanger and the high-pressure evaporator. This configuration may be advantageous, for example, to reduce the mechanical volume of the supply system. The formed single heat exchanger includes a first channel, a second channel, and a third channel, through which liquid gas flows from a first supply loop via the first channel, gaseous gas flows from a return line via the second channel, and heat transfer fluid flows from the high-pressure evaporator via the third channel. This placement of the single heat exchanger is compatible with all the embodiments described above.

[0043] According to one feature of the invention, the ratio of the gas condensed by the heat exchanger and flowing in the return line to the amount of liquid gas flowing in the first supply circuit is 16% + / - 5%. The first supply circuit is configured such that the gas flow rate flowing in the circuit is approximately 6 tons per hour. For the six tons of liquid gas flowing through the heat exchanger per hour, approximately one ton of gaseous gas flows in the return line and is condensed per hour.

[0044] The invention also includes a floating structure for storing and / or transporting liquid gas, comprising at least one liquid gas tank, at least one high-pressure gas consuming device, at least one low-pressure gas consuming device, and at least one gas supply system for supplying gas to these devices.

[0045] The present invention also includes a liquefied gas loading or unloading system, which incorporates at least one land and / or port facility and at least one floating structure for storing and / or transporting liquefied gas.

[0046] Finally, the present invention includes a method for loading or unloading liquid gas from a floating structure for storing and / or transporting gas, wherein pipes arranged on the deck of the floating structure for loading and / or unloading liquid gas are connected to a seaport or port terminal via suitable connectors to deliver liquid gas from or to tanks.

[0047] To address this technical problem, a gas supply system for at least one high-pressure gas consuming device and at least one low-pressure gas consuming device for a floating structure can also be provided. The floating structure includes at least one tank configured to contain gas, and the supply system includes:

[0048] The high-pressure gas consuming device includes at least one first gas supply circuit, comprising at least one pump configured to pump liquid gas collected in a tank.

[0049] At least one high-pressure evaporator is configured to evaporate the gas flowing in the first gas supply circuit.

[0050] At least one second circuit for supplying gas to a low-pressure gas-consuming device includes at least one compressor configured to compress gas extracted in a vapor state from a tank to a pressure appropriate for the requirements of the low-pressure gas-consuming device.

[0051] The system is characterized by a gas return line downstream of the compressor, connected to a second supply loop and extending to a tank. The system includes at least one individual heat exchanger that combines a high-pressure evaporator with a first and a second heat exchanger. Each of the first and second heat exchangers is configured to exchange heat between a gaseous gas flowing in the return line and a liquid gas flowing in the first supply loop. Therefore, the individual heat exchangers are a single component, allowing for a compact installation.

[0052] According to one aspect of the solution, the single-unit heat exchanger includes at least three channels: a first channel through which gas extracted in liquid form from the tank and flows in a first supply loop passes; a second channel through which gas flows in a return line passes; and a third channel through which a heat transfer fluid responsible for heating the gas removed in liquid form from the tank passes.

[0053] According to one aspect of the solution, the first channel is divided into three independent parts, specifically a first part for heat exchange with the second channel, a second part for heat exchange with the second channel, and a third part for heat exchange with the third channel.

[0054] According to one aspect of the invention, the compressor separates a first portion of the first channel from a second portion of the first channel. Attached Figure Description

[0055] Other features and advantages of the invention will become apparent from the following description and several exemplary embodiments, which are given for illustrative purposes and are not limited to the accompanying schematic diagrams, in which:

[0056] [ Figure 1 [Illustration] is a schematic diagram of a supply system according to a first embodiment of the present invention.

[0057] [ Figure 2 [Illustration] is a schematic diagram of a supply system according to a second embodiment of the present invention.

[0058] [ Figure 3 [Illustration] is a schematic diagram of a supply system according to an alternative embodiment of the present invention.

[0059] [ Figure 4 [Illustration] is a schematic diagram of a supply system according to a third embodiment of the present invention.

[0060] [ Figure 5[ ] is a schematic diagram of a supply system that solves the technical problem that forms the basis of this invention.

[0061] [ Figure 6 [Illustration] is a cross-sectional view of a floating tank and a dock for loading and / or unloading the tank. Detailed Implementation

[0062] The terms “upstream” and “downstream” used in the following description are used to indicate the location of an element in a liquid or vapor state gas circuit, referring to the direction of gas flow in the circuit.

[0063] Figures 1 to 5 A gas supply system 1 arranged on a floating structure is shown. The supply system 1 allows gas in a liquid, vapor, two-phase, or supercritical state to flow from a storage and / or transport tank 8 to a high-pressure gas consumption device 4 and / or a low-pressure gas consumption device 5 to supply fuel to said devices.

[0064] The floating structure may be, for example, a ship capable of storing and / or transporting liquid gas. In this case, the supply system 1 can use the liquid gas stored and / or transported by the floating structure to supply the high-pressure gas consuming device 4 and the low-pressure gas consuming device 5. The high-pressure gas consuming device 4 may be, for example, a propulsion engine, and the low-pressure gas consuming device 5 may be, for example, a generator that supplies power to the floating structure.

[0065] To ensure the flow of gas contained in tank 8 to high-pressure gas consumption device 4, supply system 1 is provided with a first supply circuit 2. The first supply circuit 2 includes a pumping component arranged within tank 8. Pump 9 enables the pumping of liquid gas and its flow, particularly within the first supply circuit 2. By extracting the liquid gas, pump 9 increases its pressure to a value between 6 and 17 bar.

[0066] The liquid gas flows from tank 8 to high-pressure gas consumption device 4, passing through the first heat exchanger 6, being pumped by auxiliary pump 10, and then through the second heat exchanger 7. Details regarding the two heat exchangers 6 and 7 will be described below.

[0067] After passing through the second heat exchanger 7, the gas flows to the high-pressure evaporator 11. The high-pressure evaporator 11 allows the state of the gas flowing in the first supply loop 2 to be changed to steam or a supercritical state. This state allows the gas to be suitable for supply to the high-pressure gas consumption device 4. The evaporation of the liquid gas can be carried out, for example, by heat exchange with a heat transfer fluid at a sufficiently high temperature, in which case the heat transfer fluid is ethylene glycol water, seawater, or water vapor.

[0068] according to Figure 1In the first embodiment shown, the first heat exchanger 6, the second heat exchanger 7, and the high-pressure evaporator 11 are separate heat exchangers. This configuration allows each heat exchanger to be designed and manufactured using techniques suitable for the fluid pressure passing through the heat exchangers. In this case, the first heat exchanger 6 can be manufactured using a technique that is cheaper than the technique used to manufacture the second heat exchanger 7, because the pressure in the first heat exchanger is significantly lower than the pressure in the second heat exchanger 7. The same applies to the high-pressure evaporator 11.

[0069] When pumping liquefied gas, the auxiliary pump 10 ensures an increase in gas pressure. When used for liquefied petroleum gas, the auxiliary pump 10 enables the pressure of the liquefied gas to be increased to 30 to 70 bar, and preferably 150 to 400 bar when used for ethane, ethylene, or liquefied natural gas which is mainly composed of methane.

[0070] With the aid of the combination of the auxiliary pump 10 and the high-pressure evaporator 11, the gas is supplied at the pressure and in a compatible state by the high-pressure gas consumption device 4. This configuration makes it possible to avoid installing a high-pressure compressor on the first supply circuit 2, which is cost-limited and produces strong vibrations.

[0071] Inside tank 8, some gaseous cargo can naturally transform into a vapor state and diffuse into tank space 12. To avoid overpressure within tank 8, the vapor state gas contained in tank space 12 must be vented. However, the first supply circuit 2 is configured to supply high-pressure gas consuming equipment 4 using liquid gas.

[0072] Therefore, the supply system 1 includes a second supply loop 3 that supplies the low-pressure gas consuming device 5 with vaporized gas. The second supply loop 3 extends between the tank space 12 and the low-pressure gas consuming device 5. To draw in the vaporized gas contained in the tank space 12, the second supply loop 3 includes a compressor 13. In addition to drawing in the vaporized gas, the compressor 13 is also capable of increasing the pressure of the vaporized gas flowing in the second supply loop 3 to an absolute pressure of 6 to 20 bar, so that the vaporized gas is at a compatible pressure for supplying the low-pressure gas consuming device 5. Thus, the second supply loop 3 enables the supply of gas to the low-pressure gas consuming device 5 while simultaneously regulating the pressure within the tank 8 by drawing in the vaporized gas present in the tank space 12.

[0073] The presence of excessive vapor state gas within tank space 12 causes overpressure within tank 8. Therefore, to reduce the pressure within tank 8, it is necessary to vent the gaseous gas. The excess vapor state can then be eliminated, for example, by burner 18. However, the supply system 1 according to the invention includes a return line 14 extending from the second supply loop 3 to tank 8.

[0074] The return line 14 is connected to the second supply circuit 3 downstream of the compressor 13, relative to the flow direction of the vapor gas flowing in the second supply circuit 3. According to the flow direction of the gaseous gas flowing in the return line 14, the gas passes through the second heat exchanger 7 in the first step, and then through the first heat exchanger 6. The heat exchange that occurs in the first heat exchanger 6 and the second heat exchanger 7 therefore takes place between the liquid gas flowing in the first supply circuit 2 and the gaseous gas flowing in the return line 14. The purpose of this heat exchange is to condense the gaseous gas in the return line 14, so that the gaseous gas is converted into a liquid state and returned to the tank 8 in this state, rather than being eliminated by the burner 18.

[0075] The inlet of the first heat exchanger 6 is where the liquid gas in the first supply loop 2 has the lowest temperature. Therefore, after passing through the first heat exchanger 6, the gas flowing in the return line 14 is condensed. Thus, the gas from the return line 14 is in a vapor state at the inlet of the first heat exchanger 6 and leaves in a liquid state after heat exchange within the first heat exchanger 6.

[0076] To ensure that the pressure of the gas flowing in the return line matches the pressure in tank 8, the return line 14 may include an expansion member 15 that can reduce the gas pressure to 1 to 3 bar absolute pressure. Once the gas is condensed, it flows into tank 8. Therefore, the first heat exchanger 6 acts as a condenser.

[0077] The ratio between the amount of vaporized gas condensed and the amount of liquid gas flowing in the first supply circuit 2 is approximately 16% + / - 5%. In other words, for approximately 6 tons of liquid gas flowing in the first supply circuit 2 per hour, approximately 1 ton of gaseous gas flowing in the return line per hour is condensed.

[0078] The second heat exchanger 7 is located downstream of the first heat exchanger 6 in the gas flow direction of the first supply loop 2 and upstream of the first heat exchanger 6 in the gas flow direction of the return line 14. Therefore, the second heat exchanger 7 ensures pre-cooling of the gaseous gas flowing in the return line 14 before the gas condenses in the first heat exchanger 6. At the inlet of the second heat exchanger 7 in the first supply loop 2, the liquid gas has previously passed through the first heat exchanger 6 and has been pumped by the auxiliary pump 10, thus increasing its temperature and pressure. Therefore, after heat exchange occurs at the second heat exchanger 7, the gas flowing in the first supply loop 2 can leave the second heat exchanger 7 in a two-phase state. Thus, the temperature of the gas flowing in the return line 14 decreases after passing through the second heat exchanger 7, achieving the aforementioned pre-cooling.

[0079] An auxiliary pump 10 is advantageously arranged between the first heat exchanger 6 and the second heat exchanger 7. The presence of the auxiliary pump 10 between the first heat exchanger 6 and the second heat exchanger 7 ensures that only liquid gas flows through the auxiliary pump 10, rather than two-phase gas that could damage the pump.

[0080] Furthermore, the auxiliary pump 10 downstream of the first heat exchanger 6 ensures an increase in liquid gas pressure without interfering with the heat exchange occurring in the first heat exchanger 6. Therefore, the condensation of the gaseous gas flowing in the return line 14 is optimally performed.

[0081] The supply system 1 also includes an auxiliary supply line 16, which extends from the first supply circuit 2 via a tap between the pump 9 and the first heat exchanger 6 to the second supply circuit 3, connecting between the compressor 13 and the low-pressure gas consuming device 5. The auxiliary supply line 16 enables power to be supplied to the low-pressure gas consuming device 5 when the flow rate of the vaporized gas formed in the tank space 12 is insufficient.

[0082] When the amount of vaporized gas in tank space 12 is insufficient, liquid gas pumped by pump 9 can flow through the auxiliary supply line 16 to supply gas to the low-pressure gas consumption device 5. For this purpose, the auxiliary supply line 16 passes through the low-pressure evaporator 17, causing the liquid gas flowing through the auxiliary supply line 16 to become vaporized. The operation of the low-pressure evaporator 17 can be, for example, the same as the operation of the high-pressure evaporator 11, that is, the gas evaporates by exchanging heat with a heat transfer fluid at a sufficiently high temperature to vaporize the liquid gas. At the outlet of the low-pressure evaporator 17, the vaporized gas flows through the auxiliary supply line 16 and is then added to the second supply circuit 3 to supply the low-pressure gas consumption device 5.

[0083] As can be seen from the above, the auxiliary supply line 16 is only used when there is not enough vapor-state gas in the tank space 12. Therefore, the auxiliary supply line 16 includes a valve 19, which controls the flow of gas in the auxiliary supply line 16 when the gas is not needed.

[0084] Figure 2 A second embodiment of the supply system 1 according to the present invention is illustrated schematically. This second embodiment differs from the first embodiment in that the return line 14 includes a main section 56 that originates at the connection point with the second power supply circuit 3 and extends to a branch point 53. At the branch point 53, the return line 14 splits into a first section 51 and a second section 52, both of which extend from the branch point 53 to the tank 8.

[0085] According to the second embodiment, the branch point 53 is located downstream of the second heat exchanger 7. Therefore, the main section 56 of the return line 14 passes through the second heat exchanger 7.

[0086] At the outlet of the second heat exchanger 7, the gaseous gas flows to the branch point 53, and can then flow in either the first section 51 or the second section 52. The first section 51 passes through the first heat exchanger 6, while the second section 52 extends to the tank 8 by bypassing the first heat exchanger 6. In other words, the gaseous gas can flow in the first section 51 and be condensed due to the heat exchange that occurs in the first heat exchanger 6, or it can flow in the second section 52 and return to the tank 8 in a gaseous state.

[0087] The selection of the section through which the gaseous gas flows depends in particular on the flow rate of the liquid gas flowing in the first supply circuit 2, which must be sufficient to completely condense the gaseous gas flowing in the return line 14. Therefore, when the amount of liquid gas flowing in the first supply circuit is greater than or equal to six times the amount of gaseous gas flowing in the return line, the gaseous gas can be directed to the first section 51, thereby enabling its condensation.

[0088] If the amount of liquid gas flowing in the first supply circuit is less than six times the amount of gaseous gas flowing in the return line, the first portion of the gaseous gas flowing in the first section 51 causes it to completely condense in the first heat exchanger 6, while a second portion of the gaseous gas, corresponding to the amount not flowing in the first section 51, flows in the second section 52 to return directly to the tank 8. In the case where little or no liquid gas flows in the first supply circuit 2, all the gaseous gas then flows in the second section 52 to return directly to the tank 8 to avoid pressure drop due to the passage through the first heat exchanger 6. In this case, the gas returns to the tank 8 in a vapor state. This occurs when very little liquid gas is used to supply the high-pressure gas consuming device 4.

[0089] To regulate the flow in the return line 14, an expansion member 15 is arranged at the first section 51, downstream of the first heat exchanger 6, while the second section 52 includes a flow rate regulating member 54. The expansion member 15 and the flow rate regulating member 54 also provide the function of expanding the gas flowing in either section.

[0090] Advantageously, in both the first section 51 and the second section 52, the flowing gas returns to the bottom of the tank 8, or at least to the region where the gas is in a liquid state. More specifically, the gas flowing in the second section 52 in a vapor state returns to the bottom of the tank in a vapor state. Therefore, the temperature and density of the liquid gas present in the tank 8 make it possible for the gaseous gas leaving the second section 52 to condense. To facilitate this condensation of the gaseous gas, the second section 52 may include a jetting member 55 arranged at one end of the second section 52 immersed in the liquid contents of the tank 8. The jetting member 55 allows the gaseous gas flowing in the second section 52 to expand so that it condenses in the tank 8. The jetting member 55 may be, for example, an ejector or a bubbling device. The return of the gaseous gas to the tank 8 via the second section 52 causes an increase in the temperature of the liquid gas present in the tank 8.

[0091] Since the features not described in the second embodiment are the same as those in the first embodiment, reference will be made to... Figure 1 The description of common elements in both embodiments is provided.

[0092] Figure 3 An alternative to the second embodiment of supply system 1 is shown, which is similar to... Figure 2 The schemes described herein are identical in all respects, except for the following components.

[0093] According to this alternative, the second heat exchanger 7 and the high-pressure evaporator 11 constitute a single heat exchanger 21. Figure 3 The solution shown allows for the design and manufacture of a single heat exchanger 21 that combines a second heat exchanger 7 and a high-pressure evaporator 11, both of which are subjected to the same high pressure, which determines the technology used to manufacture this combined heat exchanger. This solution is also evidenced by the lack of space that prevents the second heat exchanger 7 and the high-pressure evaporator 11 from being distinct from each other.

[0094] According to an alternative embodiment of the second embodiment, the branch point 53 is located downstream of the individual heat exchanger 21. Therefore, the main section 56 of the return line 14 passes through the individual heat exchanger 21. Thus, the individual heat exchanger 21 includes a first channel 24, a second channel 28, and a third channel 29, in which liquid gas from the first supply circuit 2 flows, vaporized gas from the return line 14 flows in the second channel 28, and a heat transfer fluid flows in the third channel 29, which evaporates the liquid gas flowing in the first channel 24.

[0095] In the first supply loop 2, the liquid gas at the inlet of the individual heat exchanger 21 has previously passed through the first heat exchanger 6 and has been pumped by the auxiliary pump 10, thus increasing its temperature and pressure. Therefore, after heat exchange occurs at the individual heat exchanger 21, the gas flowing in the first channel 24 may leave the individual heat exchanger 21 in a liquid, vapor, two-phase, or supercritical state.

[0096] Since the features not described in the alternative of the second embodiment are the same as those in the first and second embodiments, reference will be made to... Figure 1 and Figure 2 The description of the common elements in the embodiments is as follows.

[0097] Figure 4 A third embodiment of the supply system 1 is illustrated schematically. As an alternative to the second embodiment, the second heat exchanger 7 and the high-pressure evaporator 11 are combined to form a single heat exchanger 21; however, this third embodiment is also applicable to cases where there is a difference between the second heat exchanger 7 and the high-pressure evaporator 11, such as... Figure 2 As shown. The difference between the third embodiment and the alternative to the second embodiment is that the branch point 53 is arranged upstream of the individual heat exchanger 21. Therefore, instead of the main section 56 passing through the individual heat exchanger 21, both the first section 51 and the second section 52 pass through the individual heat exchanger 21.

[0098] Therefore, the individual heat exchanger 21 here includes: a first channel 24 in which liquid gas flows from the first supply loop 2; a second channel 28 in which gaseous gas optionally flows from the first section 51 of the return line 14; a third channel 29 in which a heat transfer fluid flows, evaporating the liquid gas flowing in the first channel 24; and a fourth channel 32 in which gaseous gas from the second section 52 of the return line 14 optionally flows. Thus, the third embodiment of the supply system 1 differs from the alternative of the second embodiment in that the individual heat exchanger 21 includes four channels instead of three.

[0099] At the outlet of the unit heat exchanger 21, the first section 51 extends to the tank 8 by passing through the first heat exchanger 6, while the second section 52 extends to the tank 8 by bypassing the first heat exchanger 6.

[0100] Figure 5 The supply system 1 shown is consistent with the above reference in all respects. Figure 1 The descriptions given are the same, except for the following elements.

[0101] The first heat exchanger 6, the second heat exchanger 7, and the high-pressure evaporator 11 constitute a single heat exchanger. Therefore, this component includes at least three channels: a first channel 24 through which gas collected in liquid form in the tank 8 and flowing in the first supply loop 2 passes; a second channel 28 through which gas flowing in the return line 14 passes; and a third channel 29 through which a heat transfer fluid passes, responsible for heating the gas collected in liquid form in the tank 8 to evaporate it and deliver it to the high-pressure gas consumption device 4.

[0102] It should be noted that this single-unit heat exchanger 36 is similar to the first heat exchanger 6, the second heat exchanger 7, and the high-pressure evaporator 11, including a first channel 24 divided into three distinct sections: a first section 33 designed for heat exchange with the second channel 28, a second section 34 designed for heat exchange with the second channel 28, and a third section 35 designed for heat exchange with the third channel 29. The first section 33 is separated from the second section 34 due to the presence of an auxiliary pump 10, which is located outside the single-unit heat exchanger 36. The auxiliary pump 10 includes an inlet port connected to the outlet of the first section 33 and a discharge port connected to the inlet of the second section 34.

[0103] Figure 5 The solution shown makes it possible to design and manufacture a single heat exchanger 36 that combines a first heat exchanger 6, a second heat exchanger 7 and a high-pressure evaporator 11, the technology of which is imposed by a first channel 24 subjected to high pressure.

[0104] Figure 6 The diagram shows a cross-sectional view of the floating structure 20, illustrating a tank 8 containing liquid and vapor gases. The tank 8 is generally prismatic and is mounted within the twin hulls 22 of the floating structure 20. The walls of the tank 8 include a primary sealing membrane intended to contact the liquid gases contained within the tank 8, a secondary sealing membrane disposed between the primary sealing membrane and the twin hulls 22 of the floating structure 20, and two thermal barriers disposed between the primary and secondary sealing membranes and between the secondary sealing membrane and the twin hulls 22, respectively.

[0105] The liquid gas loading / unloading pipe 23, located on the upper deck of the floating structure 20, can be connected to a seaport or port terminal via a suitable connector to transfer liquid gas cargo from or to tank 8.

[0106] Figure 6An example of a maritime or port terminal including loading and / or unloading equipment 25, underwater pipelines 26, and onshore and / or port facilities 27 is also shown. Onshore and / or port facilities 27 may be arranged, for example, on a pier in a port, or, according to another example, on a concrete gravity platform. Onshore and / or port facilities 27 include storage tanks 30 for liquid gases and connecting pipes 31 that connect to the loading and unloading equipment 25 via the underwater pipelines 26.

[0107] In order to generate the pressure required for transporting liquid gas, pumps equipped on land and / or port facilities 27 and / or floating structures 20 are implemented.

[0108] Of course, the present invention is not limited to the examples just described, and many modifications can be made to these examples without departing from the scope of the present invention.

[0109] As previously stated, the present invention clearly achieves the set objectives and provides a gas supply system for high-pressure or low-pressure gas-consuming devices, with high pressure achieved using pumps and evaporators, and includes means for condensing gaseous gases before they return to the gas tank. Variations not described herein can be implemented without departing from the invention, as they include the supply system according to the invention.

Claims

1. A supply system (1) for supplying gas to 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 gas, the supply system (1) comprising: at least a first supply circuit (2) of the high-pressure gas-consuming device (4) comprising at least one pump (9) configured to pump liquid gas collected in the tank (8), at least one high-pressure vaporizer (11) configured to vaporize gas circulating in the first supply circuit (2); at least one second supply circuit (3) supplying gas to the low-pressure gas-consuming device (5), the at least one second supply circuit comprising at least one compressor (13) configured to compress gas extracted from the tank (8) in a vapor state to a pressure compatible with the requirements of the low-pressure gas-consuming device (5); characterized in that the supply system (1) comprises a return line (14) connected to the second supply circuit (3) downstream of the compressor (13) and extending to the tank (8), the supply system (1) comprising at least a first heat exchanger (6) and at least a second heat exchanger (7), each configured to exchange heat between gaseous gas circulating in the return line (14) and liquid gas circulating in the first supply circuit (2), the first supply circuit (2) comprising an additional pump (10) interposed between the first heat exchanger (6) and the second heat exchanger (7).

2. The supply system (1) according to claim 1, wherein the return line (14) comprises a split point (53) dividing the return line (14) into a first section (51) and a second section (52), the first section (51) and the second section (52) both extending from the split point (53) to the tank (8), the first heat exchanger (6) being configured to exchange heat between gaseous gas circulating in the first section (51) of the return line (14) and liquid gas circulating in the first supply circuit (2), the second section (52) bypassing the first heat exchanger (6).

3. The supply system (1) according to claim 2, wherein the split point (53) is provided on the return line (14) between the first heat exchanger (6) and the second heat exchanger (7).

4. The supply system (1) according to claim 2, wherein the split point (53) is arranged on the return line (14) between the connection to the second supply circuit (3) and the second heat exchanger (7), the first section (51) and the second section (52) passing through the second heat exchanger (7).

5. The supply system (1) according to any one of claims 2 to 4, wherein, the second section (52) of the return line (14) comprises an immersion end immersed in the liquid contained in the tank (8), the second section (52) comprising a jet member (55) arranged at the immersion end.

6. The supply system (1) according to any one of claims 2 to 4, wherein the second section (52) of the return line (14) comprises a flow rate adjustment member (54).

7. The supply system (1) according to any one of claims 1 to 4, wherein the first heat exchanger (6) is configured to condense gas circulating in the return line (14).

8. The supply system (1) according to any one of claims 1 to 4, wherein The second heat exchanger (7) is configured to pre-cool the gas flowing in the return line (14).

9. The supply system (1) according to any one of claims 1 to 4, wherein The return line (14) comprises an expansion member (15) arranged downstream of the first heat exchanger (6).

10. The supply system (1) according to any one of claims 1 to 4, comprising an auxiliary supply line (16) connected to the first gas supply circuit (2) upstream of the first heat exchanger (6) and extending to the second gas supply circuit (3) downstream of the compressor (13), the supply system (1) comprising a low-pressure evaporator (17) configured to evaporate the gas flowing in the auxiliary supply line (16).

11. The supply system (1) according to any one of claims 1 to 4, wherein The pump (9) is configured to raise the pressure of the liquid gas to a value between 6 and 17 bar, and the additional pump (10) is configured to raise the pressure of the liquid gas to a value between 30 and 400 bar.

12. The supply system (1) according to any one of claims 1 to 4, wherein The compressor (13) is configured to raise the pressure of the gas to a value between 6 and 20 bar absolute.

13. The supply system of any one of claims 1 to 4, wherein, The high-pressure evaporator (11) is arranged on the first gas supply circuit (2) of the high-pressure gas-consuming device (4), downstream of the second heat exchanger (7).

14. The supply system of any one of claims 1 to 4, wherein, The second heat exchanger (7) and the high-pressure evaporator (11) form a single heat exchanger (21).

15. A floating structure (20) for storing and / or transporting a liquid gas, comprising at least one tank (8) for a liquid gas, at least one high-pressure gas-consuming device (4), at least one low-pressure gas-consuming device (5) and at least one supply system (1) for supplying gas to these devices according to any one of the preceding claims.

16. A system for loading or unloading a liquefied gas, incorporating at least one onshore and / or port facility (27) and at least one floating structure (20) for storing and / or transporting a liquefied gas according to claim 15.

17. A method for loading or unloading liquid gas from a floating structure (20) for storing and / or transporting gas according to claim 15, wherein, The pipes (23) for loading and / or unloading a liquid gas arranged on the upper deck of the floating structure (20) can be connected by suitable connectors to a sea-going or port terminal in order to deliver the liquid gas to or from the tank (8). The second heat exchanger (7) is configured to pre-cool the gas flowing in the return line (14). The return line (14) comprises an expansion member (15) arranged downstream of the first heat exchanger (6).

10. The supply system (1) according to any one of claims 1 to 4, comprising an auxiliary supply line (16) connected to the first gas supply circuit (2) upstream of the first heat exchanger (6) and extending to the second gas supply circuit (3) downstream of the compressor (13), the supply system (1) comprising a low-pressure evaporator (17) configured to evaporate the gas flowing in the auxiliary supply line (16). The pump (9) is configured to raise the pressure of the liquid gas to a value between 6 and 17 bar, and the additional pump (10) is configured to raise the pressure of the liquid gas to a value between 30 and 400 bar. The compressor (13) is configured to raise the pressure of the gas to a value between 6 and 20 bar absolute. The high-pressure evaporator (11) is arranged on the first gas supply circuit (2) of the high-pressure gas-consuming device (4), downstream of the second heat exchanger (7). The second heat exchanger (7) and the high-pressure evaporator (11) form a single heat exchanger (21).

15. A floating structure (20) for storing and / or transporting a liquid gas, comprising at least one tank (8) for a liquid gas, at least one high-pressure gas-consuming device (4), at least one low-pressure gas-consuming device (5) and at least one supply system (1) for supplying gas to these devices according to any one of the preceding claims.

16. A system for loading or unloading a liquefied gas, incorporating at least one onshore and / or port facility (27) and at least one floating structure (20) for storing and / or transporting a liquefied gas according to claim 15. The pipes (23) for loading and / or unloading a liquid gas arranged on the upper deck of the floating structure (20) can be connected by suitable connectors to a sea-going or port terminal in order to deliver the liquid gas to or from the tank (8).

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