EP3669114A1

EP3669114A1 - Device and method for supplying fuel to a power-generating facility

Info

Publication number: EP3669114A1
Application number: EP18720649.5A
Authority: EP
Inventors: Bernard Aoun; Pavel BORISEVICH; Guillaume GELIN; Romain NARME
Original assignee: Gaztransport et Technigaz SA
Current assignee: Gaztransport et Technigaz SA
Priority date: 2017-05-12
Filing date: 2018-05-07
Publication date: 2020-06-24
Also published as: FR3066189A1; WO2018206511A1; RU2019139558A; CN109257936A; JP2020519828A; FR3066189B1; CN109257936B; KR20200005414A; JP7242555B2; KR102610000B1

Abstract

The invention relates to a device (10, 110, 210) for supplying fluid fuel to a facility (12) for generating power, in particular installed on-board a ship (14), characterised in that it comprises a main tank (16) of liquefied gas, at least one first buffer tank (18) of liquefied gas, a first pipe (32) for transferring liquefied gas from the first buffer tank (18) to said facility (12), a first end (32a) of which opens into said first buffer tank (18) and a second end (32b) of which is connected to said facility (12), in order to supply fluid fuel to said facility, a second pipe (22) for transferring liquefied gas from the main tank (16) to the first buffer tank (18), said second pipe (22) comprising a first end (22a) intended for being submerged into the liquefied gas (24) contained in said main tank (16), and a second end (22b) leading into said first buffer tank (18), in order to supply liquefied gas to said first buffer tank, and means (20, 36) for applying negative pressure to said first buffer tank (18) relative to said main tank (16), which comprise at least one compressor (20) configured to apply an operating pressure lower than the atmospheric pressure to said first buffer tank.

Description

DEVICE AND METHOD FOR FUEL SUPPLYING AN ENERGY GENERATION PLANT

TECHNICAL AREA

The invention relates to a device and a method for supplying fuel to a power generation installation, in particular on board a ship.

STATE OF THE ART

The state of the art notably includes the documents WO-A1 - 2012/089891 and WO-A1-2015 / 183966.

In order to more easily transport gas, such as natural gas, over long distances, the gas is generally liquefied (to become liquefied natural gas - LNG) by cooling it to cryogenic temperatures, for example -163 ° C at atmospheric pressure. The liquefied gas is then loaded into specialized vessels.

In a liquefied gas transport vessel, for example of the LNG type, an energy production facility is provided to meet the energy requirements of the operation of the ship, in particular for the propulsion of the ship and / or the production of electricity for the vessels. equipment on board.

Such an installation commonly includes thermal machines consuming gas from an evaporator that is fed from the cargo of liquefied gas transported in the tank or tanks of the ship.

The document FR-A-2 837 783 provides for feeding such an evaporator and / or other systems necessary for propulsion by means of a submerged pump at the bottom of a tank of the ship.

A pump thus placed has disadvantages. It must undergo regular inspection operations according to the IACS (International Association of Classification Societies) code. An inspection operation of the pump may require the opening of the main tank, resulting in the vessel being immobilized and possibly damaging the tank. One solution to this problem would be to provide an opening at the bottom of the tank and to evacuate the liquefied gas from the main tank from this opening. However, the IGF and IGC (International Code for Construction and Equipment of Ships Carrying Liquefied Gases in Bulk) codes prohibit such opening in large tanks, which is the case of the main tank of a tank. ship.

The present invention provides an improvement to the present technique, which is simple, effective and economical.

SUMMARY OF THE INVENTION

The invention proposes a device for supplying combustible fluid to an energy production installation, in particular onboard a ship, comprising:

- a main tank of liquefied gas,

at least a first buffer tank of liquefied gas,

a first liquid or liquefied gas transfer line from the first buffer tank to said installation, a first end of which opens into said first buffer tank and a second end of which is connected to said installation, for supplying combustible fluid said installation,

a second liquefied gas transfer line from the main tank to the first buffer tank, said second pipe having a first end intended to be immersed in the liquefied gas contained in said main tank, and a second end opening into said first tank; buffer, for supplying said first buffer tank with liquefied gas, and

means for depressurizing said first buffer tank with respect to said main tank, which are configured to draw fluid into said first buffer tank and to apply in said first buffer tank an operating pressure lower than the pressure in said main tank, so that liquefied gas from said main tank is transferred by means of said second line and feeds said first buffer tank, characterized in that said vacuum means comprises at least one compressor and in that said operating pressure is preferably lower than atmospheric pressure.

The device according to the invention thus makes it possible to respond to the problem of the prior art. A pump immersed in the main tank is not necessary here to route liquefied gas from the main tank to the buffer tank. The depression in the buffer tank, that is to say the pressure difference between the buffer tank and the main tank, is here such that it can supply liquefied gas to the buffer tank with liquefied gas contained in the main tank. The liquefied gas thus flows in the second pipe from the main tank to the buffer tank. Conventionally, BOG contained in the main tank can be used to power the installation of a ship. In the present case, the device makes it possible to add to this source of BOG additional fluid, in gaseous or liquid form, available in the buffer tank and can be conveyed by the first pipe until installation.

The first buffer tank is adapted to be depressurized at a pressure below atmospheric pressure (and which is for example a pressure between -600 mbar and -100 mbar, or between -800 mbar and -200m barg). The compressor is capable of obtaining such a vacuum, in order to transfer the liquefied gas from the main tank to the buffer tank, even when the latter is at a pressure close to atmospheric pressure, and for example between -100 mbar and 100 mbar. or between -100 mbar and 250 mbar or between -100 mbar and 400 mbar.

This allows an immediate gas supply of the installation comprising for example engines, while on the contrary, according to the state of the art, it is necessary to wait for the increase in pressure of the main reservoir to a level sufficient to supply these engines. It should be noted in this case that the pressure must be at levels compatible with the motors, for example 8 barg or more, and that the tank and in particular the type of tank can be chosen according to its resistance to pressure. . The device according to the invention comprises one or more of the following characteristics, taken separately from each other or in combination with each other:

- said main reservoir is of the membrane type, that is to say that its walls, in particular lateral, comprise at least one metal layer forming a sealed membrane and at least one layer of thermal insulation;

said main reservoir is configured to withstand a pressure of less than or equal to 3000 mbar, and preferably less than or equal to 750 mbar;

said main reservoir is of the type without membrane;

said main tank is configured to withstand a pressure greater than or equal to 3000 mbar, and preferably greater than or equal to 6000 mbar;

said depression means comprise an output intended to be connected to said installation;

said depression means comprise at least one compressor;

a pump is connected to said first pipe and is configured to draw liquefied gas from said first buffer tank;

said compressor is connected to a third line of depression of said first buffer tank, a first end of which opens into said first buffer tank, and a second end of which is connected to an inlet of said compressor, said third pipe being configured to suck evaporation gas in said first buffer tank and for supplying said compressor with evaporation gas;

said compressor comprises an output connected to said installation for the supply of fuel gas to said installation;

said second end of said third pipe is connected to said compressor by a first circuit of a heat exchanger;

the device comprises a fourth gas transfer line from the main tank to the compressor;

said fourth pipe comprises a first end opening into said main tank, and a second end connected to said compressor; said second end of said fourth pipe is connected with said second pipe to an inlet of said first circuit of the heat exchanger, an outlet of which is connected to said compressor;

said first end of said second conduit is devoid of a pump;

said first pipe comprises at least one pump and / or a depressurization valve and / or a heat exchanger; this heat exchanger can be configured to cause the vaporization of the liquefied gas flowing in said first pipe, for the purpose of supplying fuel gas to said installation;

said pump is configured to be controlled according to a fuel gas requirement of said installation;

- The device comprises a fifth fluid return line from said vacuum means to the main tank, a first end is connected to an outlet of said vacuum means and a second end opens into said main tank;

the device comprises a second liquefied gas buffer tank;

said second buffer tank is connected to:

Said first conduit which comprises a third end opening into said second buffer tank, and

Said second pipe which comprises a third end opening into said second buffer tank;

said second buffer tank is connected to said third pipe which comprises a third end opening into said second buffer tank;

the device comprises a fifth gas supply line of said first buffer tank and said second buffer tank, a first end of which is connected to an outlet of said depressurizing means, a second end opens into said first buffer tank, and third end opens into said second buffer tank, said fifth pipe being configured to supply compressed gas to said first buffer tank and / or said second buffer tank;

said first pipe is connected by a sixth pipe to a liquefied gas spray bar in said main tank, said ramp being configured to spray liquefied gas in the form of droplets into evaporation gas of said main tank in order to condense at least a part of this evaporation gas;

each of said reservoirs is equipped with a pressure sensor and / or a level sensor;

the or each buffer tank is located below an upper end of said main tank;

the or each buffer tank is located outside said main tank;

the or each buffer tank may have a relaxation and / or separation function; at least a portion of the liquefied gas supplying a buffer tank can undergo partial vaporization and phase separation in the tank; less than half or less than 10% of the liquefied gas sucked can be vaporized in this way; the gas outlets, in liquid and gaseous form, can be connected to said installation, without (re) passing through the main tank; a small part (1 to 10%) of the LNG taken is evaporated upstream of the compressor, which makes it possible to use a reduced flow compressor; it is indeed necessary (for a gaseous LNG requirement of the given energy production installation) to suck less than when aspiring only gas (the volume of gas is approximately 600 times greater than the liquid);

said liquefied gas comprises at least one gas or pure substance; for example :

- The first pipe transfers (possibly mixed with another gas) at least partly this pure gas (in liquid form) from the buffer tank to the installation, and / or - said compressor sucks (possibly mixed with another gas ) at least partly this pure gas, and / or

said compressor supplies the installation with pure gas

(possibly mixed with another gas). In the present application, "pure" is understood to mean a single chemical body or species as opposed to a mixture of bodies or species. A pure gas is for example a light or heavy.

In the present application, the term heavy and light, respectively heavy gas or high molecular weight and a light gas or low molecular weight. In liquefied gas, the light gas in general methane. In liquefied gas, there may also be some nitrogen in the light part. The minor heavy part comprises, for example for liquefied gas propane, butane and ethane (which evaporates at a higher temperature or a lower pressure). In liquefied gas, heavy goods account for between 5.2% and 49.8% of the total liquefied gas mass. The heavies have for example molar masses between 25 and 500% greater than those of light).

The present invention also relates to a vessel, in particular for transporting liquefied gas, comprising at least one device as described above. The invention is particularly applicable to a vessel propelled by LNG (this is a particular case of liquefied gas transport vessels, if it is considered that a propulsion tank also has a transport function).

The present invention also relates to a method for supplying fuel to an energy production installation, in particular on board a ship, by means of a device as described above, characterized in that it comprises:

a step A of filling said first buffer tank, creating a depression in said first buffer tank with respect to said main tank, so that liquefied gas is transferred from the main tank to the first buffer tank.

The method according to the invention may comprise one or more of the following steps or characteristics, taken separately from each other or in combination with each other:

the method comprises a step B1 of supplying said installation by means of said compressor, by suction of gas into said first buffer tank; during step B1, said plant is powered by means of said compressor, by sampling gas from said main tank and said first buffer tank;

the method comprises a step B2 supplying said installation by means of said compressor by supplying gas to said first and / or second buffer tank to force liquefied gas to flow in said first pipe;

during step B1 or B2, said second buffer tank is supplied with liquefied gas by creating, by means of said compressor, a depression in said second buffer tank with respect to said main reservoir, so that liquefied gas is transferred from the reservoir; principal to the second buffer tank;

during step A, the pressure inside said main tank is controlled by regulating the flow of gas flowing in said fourth pipe and / or in said fifth pipe;

during step A or after step A, the pump of said first pipe is fed with liquefied gas from said first buffer tank;

the method comprises a step B3 feeding said installation via said first pipe, by actuating said pump;

during step A, the depression is maintained continuously for a predetermined duration;

the depression is carried out by applying a pressure difference between said buffer tank and said main tank, which is greater than a hydrostatic pressure generated by a substantially straight and vertical height of said second pipe, with possibly a deduction of the pressure drops in this second conduct;

said pump is controlled according to a fuel gas requirement of said installation;

- At least some valves that equip one or more of said pipes are controlled according to a fuel gas requirement of said installation; the pressure difference between the buffer tank and the main tank is increased, in order to increase the liquefied gas feed rate of the buffer tank, as soon as the level of liquefied gas in the buffer tank is below one certain threshold level;

- The pressure difference between one of the buffer tanks and the main tank is adjusted according to the filling speed of the other buffer tanks, by liquefied gas from said main tank;

- Liquefied gas contained in said first buffer tank is conveyed by said first and sixth lines to said spray boom.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description which follows, given by way of non-limiting example and with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a first embodiment of a device according to the invention, which here equips a ship,

FIGS. 2 to 6 are schematic views corresponding to FIG. 1 and illustrating steps of a method according to the invention,

FIG. 7 is a schematic view of a second embodiment of a device according to the invention, which equips a ship here,

FIGS. 8 to 12 are schematic views corresponding to FIG. 7 and illustrating steps of a method according to the invention, and

- Figure 13 is a schematic view of a third embodiment of a device according to the invention, which team here a ship.

DETAILED DESCRIPTION

In the following description, the terms "upstream" and "downstream" refer to the flow of a fluid, such as a gas or a liquid, in a pipe or circuit.

Figure 1 shows a first embodiment of a device 10 according to the invention which can be considered as allowing the supply of fuel gas to a ship, such as a liquefied gas transport vessel. The device 10 can thus be used to supply fuel gas to a power generation installation 12 on board a ship 14.

A vessel 14 comprises a reservoir 16 or several similar tanks 16 for storing liquefied gas. The gas is, for example, methane or a mixture of gases comprising methane. The or each tank 16 may contain gas in liquefied form at a predetermined pressure and temperature, for example at atmospheric pressure and a temperature of the order of -163 ° C. One or more tanks 16 of the ship can be connected to the installation 12 by a device 10 according to the invention. The number of tanks is thus not limiting. It is for example between 1 and 6. Each tank 16 can have a capacity of between 1000 (or even 100) to 50 000m3.

In what follows, the expression "the tank 16" will have to be interpreted as "the or each tank 16".

The reservoir 16 contains liquefied gas 16aa as well as gas 16ab resulting from an evaporation, in particular a natural evaporation, of the liquefied gas 16aa in the tank 16. Of course, the liquefied gas 16aa is stored at the bottom of the tank 16 while the gas 16ab evaporation is located above the level of liquefied gas in the tank, schematically represented by the letter N.

In what follows, "LNG" designates liquefied gas, that is to say gas in liquid form, "BOG" designates evaporation gas, "NBOG" designates natural evaporation gas, and "FBOG Refers to forced evaporation gas, these acronyms being known to those skilled in the art because they correspond to the initials of associated English expressions.

In the embodiment shown in FIG. 1, one end 22a of a pipe 22 is immersed in the LNG 16aa of the tank 16. This end is preferably devoid of a pump, in order to avoid maintenance, and is preferably located at the bottom of the tank to ensure that the line is only fed with liquid LNG even when the tank is almost empty. In this application, the term "bottom" of tank or tank, a position located less than one meter from a bottom wall of the tank, the bottom wall being the wall of the tank closest to the center of the earth in operation.

The pipe 22 comprises a bypass and comprises two ends located outside the tank 16. One of these ends 22d forms an LNG filling port of the tank 16 and is therefore accessible by a user, in particular during the LNG loading of the tank. tank 16 of the ship.

The other end 22b of the pipe is connected to a buffer tank 18, also located outside the tank 16. A valve 23d, 23b is associated with each of the ends 22d, 22b. The valve 23d makes it possible to block the circulation of fluid in the pipe 22 and thus the supply of LNG to the tank 16. The valve 23d can also form a non-return valve. The valve 23b makes it possible to block the supply of fluid to the buffer tank 18, in particular during the bunkering of the main tank 16.

A spray boom 52 of LNG droplets is located in the upper part of the tank 16, above the level N. The ramp 52 is thus configured to spray droplets of LNG in the tank BOG. This makes it possible to force the recondensation of the BOG in the tank 16.

The reservoir 16 further comprises a BOG input 16a and a BOG output 16b. The outlet 16b is connected to an end 30a of a pipe 30 which also comprises a bypass defining two ends situated outside the tank 16. One of these ends 30c forms a BOG evacuation port of the tank 16, which is accessible by a user, in particular during the LNG loading of the tank 16 of the ship.

The other of the ends 30b of the pipe 30 is connected to an input 28aa of a first circuit 28a of a heat exchanger 28, an output 28ab of which is connected to an input 20a of a compressor 20. The first circuit 28a is a cold circuit, the fluid flowing in this circuit 28a being intended to be heated by a fluid flowing in a second circuit 28b or hot circuit of the exchanger 28. A valve 31a, 31c is associated with each of the ends 30a, 30c. The valve 31a is used to block the flow of fluid in the pipe 30 and thus the discharge of BOG tank 16. The valve 31 may also form a non-return valve. The valve 31c makes it possible to block the evacuation of BOG towards the end 30c and the associated port.

The inlet 16a of the reservoir 16 is connected to one end 38b of a pipe 38, the other end 38a is connected to an outlet 20b of the compressor 20. A valve 39 is associated with this pipe 38 and blocks the circulation of fluid since the output of the compressor 20 to the reservoir 16. The outlet 20b of the compressor 20 is further connected by a valve 41 to the installation 12.

The buffer tank 18 comprises three ports, including an inlet 18a connected to the end 22b of the pipe 22, and two outlets 18b and 18c. The inlet 18a is configured to receive LNG, the buffer tank 18 being intended to be supplied with LNG directly from the tank 16.

The output 18b is a gas outlet and in particular BOG and the output 18c is an output of LNG. The outlet 18b is connected to an end 26a of a pipe 26 whose opposite end 26b is connected to the inlet 20a of the compressor 20. In the example shown, the BOG leaving the buffer tank 18 is preheated by the exchanger 28 for supplying the compressor 20. For this, the pipe 26 is connected to the pipe 30 upstream of the exchanger 28, and more particularly upstream of the circuit 28a, so that the BOG comes from both the tank 16 and the buffer tank 18 can supply the circuit 28 and be heated before supplying the compressor 20.

The pipe 26 comprises a valve 27 able to block the circulation of fluid in the pipe 26 and in particular the evacuation of BOG from the buffer tank 18 to the exchanger 28.

The outlet 18c is connected to an end 32a of a pipe 32 which is connected to the installation 12 with the outlet 20b of the compressor 20. This pipe 32 here comprises or is connected to a pump 36 and to a heat exchanger 34. The pipe 32 further comprises two valves 33a, 33b, including for example a depressurizing valve 33b. In the example shown, from upstream to downstream, that is to say from the tank 18 to the outlet 20b of the compressor 20, are arranged the pump 36, the valve 33b, the exchanger 34, and the valve 33a.

The pipe 32 is connected to the outlet 20b of the compressor 20, just upstream of the valve 41. Furthermore, at the outlet of the valve 33a, the pipe 32 is connected by a valve 33c to the pipe 38, just downstream of the valve 39.

In the example shown, the LNG discharged from the buffer tank 18 through the pump 36 is evaporated by the exchanger 34 before supplying the installation 12. For this, the pipe 32 is connected to an input 34aa of a first circuit 34a of a heat exchanger 34, an output 34ab of which is connected to the valve 33a. The first circuit 34a is a cold circuit, the fluid flowing in this circuit 34a being intended to be heated by a fluid flowing in a second circuit 34b or hot circuit of the exchanger 34.

In the case where the valve 33b is a depressurization valve and would vaporize the entire LNG FBOG, FBOG would be heated by the exchanger 34 before supplying the installation 12. Thus, advantageously, the valve 33b is configured so that the output FBOG pressure corresponds to the operating pressure of the fuel gas in the installation 12.

A pipe 50 equipped with a valve 51 connects the spray boom

52 to the pipe 32. Its upstream end is connected to the pipe 32, between the pump 36 and the valve 33b, that is to say just downstream of the pump 36, and its downstream end is connected to the ramp 52 It is thus understood that LNG contained in the buffer tank 18 can feed the spray boom 52, as mentioned in the foregoing.

The buffer tank 18 is intended to be supplied with LNG from the tank 16. The operating pressure inside the buffer tank 18 is lower than the storage pressure of the LNG inside the tank 16. The supply of the tank buffer 18 LNG will therefore cause a partial vaporization of the LNG, resulting on the one hand by the generation of FBOG in the buffer tank 18, and the cooling of the remaining LNG in the buffer tank 18, which is called "subcooled liquefied gas". The buffer tank 18 contains gas in liquefied form at a predetermined pressure and temperature.

The buffer tank 18 thus contains subcooled liquefied gas 18aa as well as gas 18ab resulting from evaporation, here forced, liquefied gas 16aa from the tank 16. Naturally, the liquefied gas liquefied (or LNG) 18aa is stored at the bottom of the buffer tank 1 8 while the evaporation gas (or FBOG) 18ab is located above the level of liquefied gas in the buffer tank 18, schematically represented by the letter L.

The compressor 20 is here used to apply the operating pressure inside the buffer tank 18. It is thus configured to depressurize the buffer tank 18 with respect to the tank 16. The pressure difference between them can be such that it is sufficient to force the circulation of LNG from the tank 16 to the buffer tank 18. In the latter case, it is therefore understood that a pump immersed at the end 22a of the pipe 22 is not necessary. The conditions imposed by the compressor 20 on the buffer tank 18 are determined to generate LNG in the buffer tank 18.

As an alternative or additional feature, the pump 36 could be configured to participate in the depression of the buffer tank 18 vis-à-vis the main tank 16.

When the amount of LNG in the buffer tank 18 is too large and a threshold level is likely to be reached, LNG can be transferred from the LNG outlet of the buffer tank 18 to the plant 12 and / or the ramp. spray 52 in the tank 16.

The LNG forms a cooling capacity that can be stored in the buffer tank 18 when it is not necessary, for example during phases where the amount of NBOG produced is insufficient to meet the demand.

In the example shown, the vacuum in the tank 18 must be such that it allows the flow of LNG in the pipe 22. The pipe 22 has a vertical portion forming a plunger and immersed in the LNG tank 16, its upper end being connected by a T to the rest of the pipe 22. The pressure difference between the two tanks 16, 18 should preferably be greater than the hydrostatic pressure generated by the height of the pipe 22 (more precisely the height of the vertical portion 22 from the bottom of the tank to T - car when the tank 16 is empty, the LNG must be able to be raised to this height), less the pressure drop in the pipe 22. In a variant, the pressure difference may be smaller if the tank 18 (and more precisely the outlet 22b) is lower than this height, and if the pipe 22 is primed (for example by a lower pressure difference when the tank 16 is almost full).

The pressure difference can be regulated as follows:

the gas requirement for the installation 12 controls the pump 36 (the gas requirement being determined, for example, by the difference between the measured gas flow rate between the outlet 32b and the installation 12, and the set point of the installation 12) ,

the reservoir 18 has a level sensor; as soon as the level in this reservoir 18 is lower than a lower threshold level, the pressure difference is increased in order to increase the flow rate in the reservoir 18 (in the same way, an upper threshold level can be provided, the pressure difference being diminished or canceled as soon as such a level is reached).

A fuel gas supply device has two main functions:

supplying fuel gas from the main tank to the vessel's installation at a desired flow rate (for example from 50 to 2000 kg / h), at a pressure (for example from 6 to 300 bar) and at a temperature (for example 20 ° C) predetermined; the fuel gas can be either in gaseous form (vapors) or in liquid form;

adjusting the pressure inside the main tank 16 in an acceptable range (for example between -100 and +700 mbar or between -700 and 6000 mbar).

The device 10 presented is composed of the main tank 16 designed to contain cryogenic liquid, for example at atmospheric pressure. (For example with a volume of 1000 (or even 100) to 10 000 m3 and a permissible pressure of -100 to +700 mbarg or between -700 and 6000 mbarg) and the buffer tank 18 for containing cryogenic liquids (for example with a volume of 1 to 20 m3 and with a permissible pressure of -500 to 6000 mbarg). A pressure difference is created with the compressor 20 and / or the pump 36, between the main tank 16 and the buffer tank 18 (for example +500 mbar in the main tank with respect to the buffer tank) in order to be able to transfer liquid from the main tank 16 to the buffer tank 18. The liquid in the buffer tank 18 is compressed by the pump 36 and sent to the installation 12 via the spray valve 33b. The level of the liquid in the buffer tank 18 is controlled with appropriate instrumentation between, for example, 10% and 90% of the volume of the buffer tank. In this way, the pump 36 is always supplied with 100% liquid gas (a mixture of liquid and gaseous natural gas would damage the pump). The control of the device and the appropriate instrumentation are designed to maintain the pressure in the main tank 16 at the desired level (for example between -100 and 700 mbar). Thus, each reservoir of the device 10 is advantageously equipped with a pressure sensor and / or a level sensor.

FIGS. 2 to 6 illustrate phases of operation of the device of FIG. 1, which may correspond to the speed phases of the ship equipped with this device.

The feeding process is described here in three phases:

1. Minimum consumption: natural evaporation covers the energy demand of the installation (the propulsion engines of the ship are stopped or operate at low load, the gas is mainly used to meet the needs for electricity and heating).

2. Normal consumption: natural evaporation does not cover the energy demand of the ship.

3. No consumption (all on-board gas consumers of plant 12 are shut down except for the gas compressor). 4. Filling.

1. Minimum consumption (see Figure 2)

In the operation phase illustrated in Figure 2, the main engine of the vessel is stopped and the power consumption is less than the maximum capacity capacity of the compressor 20 (<2 ~ 3 MW).

The evaporation of the LNG 16aa in the tank 16 causes an increase in the pressure of the BOG 16ab in the tank 16. The BOG 16ab is sucked by the compressor 20, heated in the exchanger 28 and sent to the installation 12. This allows to maintain the pressure in the tank 16 below an acceptable threshold value.

In order to regulate the pressure in the tank 16, it is possible to:

setting the BOG flow rate sent to the compressor 20 (if this flow rate is greater than the natural evaporation rate, the pressure in the reservoir 16 decreases, and if this flow rate is lower than the natural evaporation rate, the pressure in the reservoir increases );

- reinjecting a portion of compressed gas (leaving the compressor 20) in the main tank 16 (for example, if the specifications of the compressor 20 do not reduce the compressor inlet flow below a certain value (which is here higher than the natural rate of evaporation), a portion of the compressed gas is reinjected into the tank 16 through the pipe 38, to adjust the pressure in the tank 16).

The device 10 thus supplies the needs of the installation 12 of gas coming from the tank 16, and maintains the pressure inside this tank at the desired level (for example between -100 and 700 mbar).

2. Normal consumption

In the second phase of operation, the consumption is normal.

The natural evaporation in the tank 16 is insufficient to meet the energy demand of the installation 12. A forced evaporation is necessary to meet the energy demand of the ship. This phase includes two steps:

- Prepare the forced evaporation: fill the buffer tank 18 and the pump 36 with liquid natural gas.

- Forced evaporation: the liquid from the buffer tank 18 is sent to the installation forcing its vaporization.

- Prepare forced evaporation (Figure 3)

The first step consists in creating a pressure difference between the main tank 16 and the buffer tank 18, for example -500 mbar. By reducing the pressure in the buffer tank 18 and / or by increasing the pressure in the reservoir 16. The pressure in the reservoir 16 can be increased as described above by re-injecting compressed BOG. The pressure in the buffer tank 18 can be reduced by drawing natural gas into the buffer tank by means of the compressor 20. With this pressure difference, it is possible to suck up the LNG contained in the tank 16, from a height of 10 m. .

If the pressure is increased in the reservoir 16, the BOG contained in the tank 16 tends to push the LNG out of the tank 16 and thus to force its circulation in the pipe 22 to the buffer tank 18. If the pressure decreases in the buffer tank 18, the LNG is sucked from the tank 16 to the buffer tank 18. The pressure difference contributes to the partial evaporation (flash) and the formation of BOG in the buffer tank 18. This BOG is sucked by the compressor 20 so as to maintain the pressure difference between the reservoirs 16, 18.

The second step is to fill the pump 36 with liquid natural gas. Once the buffer tank 18 filled with liquid natural gas at the desired level, for example up to 90% of its volume, the LNG is sent by gravity to the pump 36. The pump 36 must be filled completely with liquid, otherwise bubbles may appear and damage the pump. LNG flows in line 32 to pump 36 and passes through it, keeping pump 36 stopped. These operations can be combined with the first phase of operation, to regulate the pressure in the main tank 16.

- forced evaporation (Figure 4)

The liquid from the buffer tank 18 is sent by forcing the flow of fluid to the installation 12.

LNGs from the buffer tank 18 are sent to the installation 12 via the exchanger 34. The LNG flow rate sent to the installation 12 is regulated by the pump 36. The installation 12 primarily accepts the gas from compressor 20 (which manages the pressure in the tanks 16, 18), the additional gas being obtained by the pump 36 which is used to circulate the LNG to the valve 33b for vaporization, preferably complete the LNG, before its reheating in the exchanger 34. As described above, the LNG feed of the buffer tank 18 is obtained by depressurizing the reservoir 18 vis-à-vis the reservoir 16. The LNG outlet of the buffer tank 18 is regulated by the pump 36. The level of LNG in the buffer tank 18 is regulated to be maintained at the desired level, for example between 10% and 90% of its volume.

These operations can be combined with the first phase of operation, in order to regulate the pressure in the main tank 16.

3. No consumption (see Figure 5)

This operating phase is activated in case of emergency. The installation 12 is closed, that is to say that no fuel gas consumption occurs. The exchanger 28, the compressor 20 and the pump 36 operate by means of an emergency electricity generator.

For this phase, we consider that the tanks 16, 18 contain LNG. The pump 36 circulates LNG from the buffer tank 18 to the ramp 52. Since there is a pressure difference between the tanks 16, 18, LNG continues to flow from the tank 16 to the buffer tank 18 and vaporizes in the latter. This means that the LNG formed in the buffer tank 18 is subcooled by comparison with the LNG contained in the tank 16. The ramp 52 is fed with sub-cooled liquefied gas from the buffer tank 18 and sprays droplets of this liquefied gas into the tank BOG 16 This allows BOG to be condensed in the tank 16, and thus participate in the reduction and maintenance of the pressure in the main tank 16.

The pressure in the tank 16 is thus regulated by the flow of LNG from the buffer tank 18 and sprayed by the boom 52. This operating phase can be combined with the first or the second phase, to reduce the pressure in the main tank. .

4. Filling (see Figure 6)

The valve 23d is open. The LNG of a filling station is sent into the tank 16. The BOG which evaporates during filling is evacuated by also opening the valves 31a and 31c, so as to create a free flow of BOG to the station.

FIG. 7 represents an alternative embodiment of the device 1 10 according to the invention, which differs from the device 10 in particular in that it comprises two buffer tanks 18 and 40.

The features described above in connection with the device 10 apply to the device 1 10 in that they do not contradict the following.

The pipe 22 is connected to each tank 18, 40 and comprises an end 22b connected to an LNG inlet 18a of the tank 18 and an end 22c connected to an LNG inlet 40a of the tank 40. A valve 23e, 23f is associated with each of these ends 23b, 23d, in addition to the above-mentioned valves 23b, 23d of the pipe 22.

Each buffer tank 18, 40 here comprises four ports, including two inputs 18a, 40a, 18d, 40d and two outputs 18b, 40b and 18c, 40c. The inlets 18a, 40a are respectively connected to the ends 22b, 22c of the pipe 22 and are configured to receive LNG, each buffer tank 18, 40 being intended to be supplied with LNG coming directly from the tank 16. The outputs 18b, 40b are gas outlets and in particular BOG and the outputs 18c, 40c are LNG outputs. The outlets 18b, 40b are connected to ends 26a, 26c, respectively, of the pipe 26, the opposite end 26b of which is connected to the inlet 20a of the compressor 20 or to the inlet 28a of the circuit 28 of the exchanger 28 as mentioned in the foregoing.

In addition to the valve 27, the pipe 26 comprises a valve associated with each of its ends 26a, 26b.

Another line 42 connects the outlet 20b of the compressor 20 to the inlets 18d, 40d of the tanks. This is a gas inlet, or compressed BOG, reservoirs 18, 40 can be fed with compressed BOG, as will be described in more detail below. The pipe 42 comprises a valve 43 for blocking the flow of fluid from the outlet of the compressor 20 to the tanks 18, 40. In addition, each inlet 18d, 40d is associated with a valve for isolating the tanks one screw to the other.

The outlets 18c, 40c of the reservoirs 18, 40 are connected to ends 32a, 32c of a duct 32 which is connected to the outlet 20b of the compressor 20. This duct 32 here comprises or is connected to a heat exchanger 34. conduit further comprises two valves 33a, 33b, including for example a depressurizing valve 33b. In the example shown, from upstream to downstream, that is to say from the tanks 18, 40 to the outlet 20b of the compressor 20, are arranged the valve 33b, the exchanger 34, and the valve 33a. . Valves are further associated with each of the outlets 18c, 40c.

In the example shown, the LNG discharged from the buffer tank 18 is preheated by the exchanger 34 before supplying the installation 12. For this, the pipe 32 is connected to an input 34aa of a first circuit 34a of a heat exchanger 34, an output 34ab of which is connected to the valve 33a. The first circuit 34a is a cold circuit, the fluid flowing in this circuit 34a being intended to be heated by a fluid flowing in a second circuit 34b or hot circuit of the exchanger 34.

In the case where the valve 33b is a depressurization valve and would vaporize the entire LNG FBOG, FBOG would be heated by the heat exchanger before supplying the installation 12. Thus, advantageously, the valve 33b is configured so that the output FBOG pressure corresponds to the operating pressure of the combustible gas in the installation.

A pipe 50 connects the spray boom 52 to the pipe 32. Its upstream end is connected to the pipe 32, upstream of the valve 33b, and its downstream end is connected to the ramp 52. It is thus understood that LNG contained in the buffer tanks 18, 40 can feed the spray boom 52, as mentioned above.

In the example shown, the vacuum in the tank 18 must be such that it allows the flow of LNG in the pipe 22. The pipe 22 has a vertical portion forming a plunger and immersed in the LNG tank 16, its upper end being connected by a bend to the remainder of the pipe 22. The pressure difference between the two tanks 16, 18 should preferably be greater than the hydrostatic pressure generated by the height of the pipe 22 (more precisely the height of the vertical portion of the pipe 22 from the bottom of the tank to the elbow - because when the tank 16 is empty, it must be possible to raise the LNG up to this height), less the pressure drop in the pipe 22. In a variant, the pressure difference may be smaller if the reservoir 18 (and more precisely the outlet 22b) is lower than this height, and if the pipe 22 is primed (for example by a pressure difference greater than ble when the tank 16 is almost full).

The pressure difference can be regulated as follows:

the gas requirement for the installation 12 controls the valves associated with the outlets 18c, 40c of the tanks 18, 40,

the pressure difference is adjusted so as to fill the buffer tanks sufficiently quickly (thus it is also subject to the need for gas for the installation 12). Each reservoir 18, 40 functions as the reservoir 18 of the device 10. The reservoirs 18, 40 also have an additional function, because of their connection to the outlet 20b of the compressor 20. The compressed BOG exiting the compressor 20 and supplying the reservoirs 18, 40 makes it possible to pressurize these reservoirs 18, 40 and to force the passage of LNG 18aa, 40aa through their outlets 18c, 40c. It is therefore not necessary for these outlets to be equipped with a pump, such as that of the device 10, to force LNG out of the buffer tanks 18, 40.

A fuel gas supply device has two main functions:

supplying fuel gas from the main tank 14 to the ship's installation 12 at a desired flow rate (for example from 50 to 2000 kg / h), at a pressure (for example from 6 to 300 bars) and at a temperature (for example example 20 ° C) predetermined. The combustible gas can be either in gaseous form (vapors) or in liquid form;

- Set the pressure inside the main tank 16 in an acceptable range (for example between -100 and +700 mbar g).

The device 10 presented is composed of the main tank 16 designed to contain cryogenic liquid, for example at atmospheric pressure (for example with a volume of 1000 to 10,000 m3 and a pressure allowable of -100 to +700 mbar) and the buffer tanks 18 intended to contain cryogenic liquids (for example with a volume of 1 to 20 m3 and with a permissible pressure of -500 to 6000 mbar). A pressure difference is created with the compressor 20 between the main tank 16 and the buffer tanks 18, 40 (for example +500 mbar in the main tank relative to the buffer tank) in order to be able to transfer liquid from the main tank 16 to the tanks buffer 18, 40. The liquid in the buffer tanks 18, 40 is sent to the plant 12 via the spray valve 33b. The level of the liquid in each buffer tank is controlled with a appropriate instrumentation between, for example, 10% and 90% of the volume of the buffer tank.

The control of the device and the appropriate instrumentation are designed to maintain the pressure in the main tank 16 at the desired level (for example between -100 and 700 mbar). Thus, each tank of the device 1 10 is advantageously equipped with a pressure sensor and / or a level sensor.

FIGS. 8 to 12 illustrate phases of operation of the device of FIG. 7, which may correspond to the speed phases of the ship equipped with this device.

The liquefied gas cooling process is described here in three phases:

1. Minimum consumption: natural evaporation covers the energy demand of the installation 12 (the propulsion engines of the vessel are stopped or operate at low load, the gas is mainly used to meet the needs for electricity and heating).

3. No consumption (all on-board gas consumers of plant 12 are shut down except for the gas compressor).

4. Filling.

This is a sequential process, in which the buffer tanks 18 and 40 are alternately filled and emptied. This description will focus solely on the filling and emptying of the tank 18, the process for the tank 40 being symmetrical.

1. Minimum consumption (see Figure 8)

In the operation phase illustrated in FIG. 8, the main engine of the ship is stopped and the power consumption is less than the maximum capacity of the compressor 20 (<2 ~ 3 MW). The evaporation of the LNG 16aa in the tank 16 causes an increase in the pressure of the BOG 16ab in the tank 16. The BOG 16ab is sucked by the compressor 20, heated in the exchanger 28 and sent to the installation 12. This allows to maintain the pressure in the tank 16 below an acceptable threshold value.

In order to regulate the pressure in the tank 16, it is possible to:

- reinjecting a portion of compressed gas (leaving the compressor 20) in the main tank 16 (for example, if the specifications of the compressor 20 do not reduce the compressor inlet flow below a certain value (which is here greater than the natural rate of evaporation), a portion of the compressed gas is reinjected into the tank 16 via line 38).

The device 10 thus supplies the needs of the installation 12 of gas coming from the tank 16, and maintains the pressure inside this tank at the desired level (for example between -100 and 700 mbar). 2. Normal consumption

In the second phase of operation, the consumption is normal.

Natural evaporation in the tank 16 is insufficient to meet the energy demand of the installation 12. Forced evaporation is necessary to meet the energy demand of the ship. This phase includes two steps:

- Prepare the forced evaporation: fill the buffer tank 18 with liquid natural gas from the tank 16.

Forced evaporation: the liquid coming from the buffer tank is sent to the exchanger and then to the installation (while the other buffer tank 40 is filled with LNG). - Prepare forced evaporation (see Figure 9)

The first step is to create a pressure difference between the main tank 16 and the buffer tank 18, for example -500 mbar, by reducing the pressure in the tank 18 and / or by increasing the pressure in the tank 16. The pressure in the tank 16 can be increased as described in the first phase. The pressure in the tank 18 can be reduced by drawing natural gas into this tank, by means of the compressor 20. With this pressure difference (-500 mbar), it is possible to suck LNG from the main tank 16, since a height of about 10m.

If the pressure is increased in the reservoir 16, the reservoir BOG

16 forces the LNG outlet of this tank and its circulation in the pipe 22 to the tank 18. If the pressure decreases in the buffer tank 18, LNG contained in the tank 16 is sucked up to the reservoir 18. The difference pressure contributes to the partial evaporation of LNG in the tank 18. The evaporated gas is sucked by the compressor 20, which maintains a pressure difference between the tanks 16, 18. The tank 18 is filled with liquid natural gas, for example up to 90% of its volume.

These operations can be combined with the first phase of operation, in order to regulate the pressure in the tank 16.

- forced evaporation (Figure 10)

The second step consists in pressurizing the reservoir 18 with the compressed natural gas at the outlet of the compressor 20.

The pipe 22 and the valve 23b used to fill the tank 18 with liquid and to draw the natural gas from this tank are closed. Compressed gas leaving the compressor 20 is sent (partially if necessary) to the tank 18 to pressurize it. This makes it possible to force the circulation of LNG from the tank 18 to the exchanger 34 and the installation 12.

While tank 18 is used to supply LNG to the facility

12, the tank 40 is filled with LNG from the tank 16 (only the valves 23d and 23e are then closed, the valves 23b and 23f being open). The device 1 10 is advantageously designed to be able to fill the tank 40 at a speed greater than the discharge rate of the LNG of the tank 18 with the compressor 20.

The flow rate and the LNG pressure at the outlet of the buffer tank 18 are regulated by the valve 33b. The tank 18 is used until its LNG level is too low (5% of the volume for example). At this time, the tank 40 is ready to supply LNG, in turn, to the installation 12. Next, the tank 16 is filled with LNG, as described in the first step.

During this phase, the tanks 18, 40 are thus alternately filled with LNG and compressed with the compressor 20 to supply LNG to the installation 12.

These operations can be combined with the first phase of operation, in order to regulate the pressure in the tank 16. 3. No consumption (see Figure 1 1)

This operating phase is activated in case of emergency. The installation 12 is closed, that is to say that no fuel gas consumption occurs. The exchanger 28 and the compressor 20 operate by means of an emergency electricity generator.

For this phase, we consider that the tanks 16, 18 contain LNG. The compressor 20 is used to send compressed gas to the tank 18 and increase the pressure in this tank, which forces the LNG outlet of this tank to the ramp 52 for the purpose of spraying LNG into the BOG of the tank 16 This makes it possible to condense BOG in the tank 16, and thus participate in the reduction and maintenance of the pressure in the main tank 16.

The pressure in the tank 16 is thus regulated by the flow of LNG from the buffer tank 18 and sprayed by the ramp 52.

Once the reservoir 18 is empty, this operation is repeated with the reservoir 40 while the reservoir 18 is filled.

This operating phase can be combined with the first or the second phase, to reduce the pressure in the main tank 16. 4. Filling (see Figure 12)

The valve 23d is open. The LNG of the filling station is sent into the tank 16. The BOG which evaporates during filling is evacuated by also opening the valves 31a and 31c, so as to create a free flow of BOG towards the station.

FIG. 13 represents an alternative embodiment of the device 210 according to the invention, which differs from the device 1 10 notably in that it further comprises a pump 36.

The features described above in connection with the device 1 10 apply to the device 210 to the extent that they do not contradict the following.

The pump 36 is located on a pipe 54, an upstream end of which is connected to the outlets 18c, 40c of the reservoirs 18, 40, just downstream of their valves, and a downstream end of which is connected to the pipe 32, just upstream of the valve 33b. This pipe 54 comprises a valve 56 and extends in parallel with a portion of the pipe 32 which also comprises an additional valve 58. This configuration offers the possibility of using or not the pump 36 to evacuate the LNG contained in the tanks 18, 40, to the spray boom 525 and / or the installation 12.

The device thus has a hybrid operation with respect to the devices 10, 1 10.

Claims

1. Device (10, 1 10, 210) for supplying combustible fluid to a power generation installation (12), in particular on a ship (14), comprising:

a main tank (16) of liquefied gas,

at least a first buffer tank (18) of liquefied gas,

a first liquefied gas transfer line (32) from the first buffer tank (18) to said installation (12), a first end (32a) of which opens into said first buffer tank (18) and a second end thereof (32b) is connected to said installation (12), in order to supply combustible fluid to said installation,

a second liquefied gas transfer line (22) from the main tank (16) to the first buffer tank (18), said second pipe (22) having a first end (22a) intended to be immersed in the liquefied gas (24) contained in said main tank (16), and a second end (22b) opening into said first buffer tank (18), for supplying said first buffer tank with liquefied gas, and

means (20, 36) for depressurizing said first buffer tank (18) with respect to said main tank (16), which are configured to draw fluid into said first buffer tank and to apply a pressure in said first buffer tank; operating pressure lower than the pressure in said main tank, so that liquefied gas from said main tank (16) is transferred by means of said second pipe (22) and feeds said first buffer tank (18), characterized in that said vacuum means comprises at least one compressor (20) and in that said operating pressure is less than atmospheric pressure.

2. Device (10, 1 10, 210) according to the preceding claim, wherein said vacuum means comprises an outlet (20b) intended to be connected to said installation (12).

3. Device (10, 1 10, 210) according to one of the preceding claims, wherein a pump is connected to said first pipe and is configured to draw liquefied gas from said first buffer tank.

4. Device (10, 1 10, 210) according to the preceding claim, wherein said compressor (20) is connected to a third conduit (26) of depression of said first buffer tank (18), a first end (26a ) opens into said first buffer tank (18), and a second end (26b) of which is connected to an inlet (20a) of said compressor, said third pipe being configured to suck evaporation gas into said first buffer tank and to supply said compressor in evaporation gas.

5. Device (10, 1 10, 210) according to the preceding claim, wherein said compressor (20) comprises an outlet (20b) connected to said installation for supplying fuel gas to said installation.

The device (10, 1, 10, 210) according to claim 4 or 5, wherein said second end of said third conduit is connected to said compressor by a first circuit of a heat exchanger.

7. Device (10, 1 10, 210) according to one of the preceding claims, wherein the device comprises a fourth gas transfer line from the main tank to the compressor.

8. Device (10, 1 10, 210) according to the preceding claim, wherein said fourth pipe has a first end opening into said main tank, and a second end connected to said compressor.

9. Device (10, 1 10, 210) according to the preceding claim, wherein said second end of said fourth pipe is connected with said second pipe to an inlet of said first circuit of the heat exchanger, an output of which is connected to said compressor.

10. Device (10, 1 10, 210) according to one of the preceding claims, wherein said first end (22a) of said second conduit (22) is devoid of pump.

1 1. Device (10, 1 10, 210) according to one of the preceding claims, wherein said first pipe comprises at least one pump and / or a depressurization valve and / or a heat exchanger.

12. Device (10, 1 10, 210) according to the preceding claim, wherein said pump is configured to be controlled according to a fuel gas requirement of said installation.

13. Device (10, 1 10, 210) according to one of the preceding claims, wherein it comprises a fifth fluid return line from said vacuum means to the main tank, a first end is connected to an outlet of said vacuum means and a second end of which opens into said main tank.

14. Device (1 10, 210) according to one of the preceding claims, wherein it comprises a second buffer tank (40) of liquefied gas.

15. Device (1 10, 210) according to the preceding claim, wherein said second buffer tank (40) is connected to:

said first conduit (32) comprising a third end (32c) opening into said second buffer tank (40), and

- said second pipe (22) which comprises a third end (22c) opening into said second buffer tank (40).

16. Device (1 10, 210) according to the preceding claim, in accordance with claim 4 or 10, wherein said second buffer tank (40) is connected to said third pipe (26) which comprises a third end (26c) opening in said second buffer tank (40).

The device (1 10, 210) according to claim 14 or 15, wherein it comprises a fifth gas supply line (42) of said first buffer tank (18) and said second buffer tank (40), a first end (42a) is connected to an outlet (20b) of said vacuum means (20), a second end (42b) opens into said first buffer tank (18), and a third end (42c) opens into said second tank buffer (40), said fifth pipe being configured to supplying compressed gas to said first buffer tank and / or said second buffer tank.

18. Device (10, 1 10, 210) according to one of the preceding claims, wherein said first conduit is connected by a sixth pipe to a liquefied gas spray bar in said main tank, said ramp being configured to spray liquefied gas in the form of droplets in evaporation gas of said main tank to condense at least a portion of this evaporation gas.

19. Device (10, 1 10, 210) according to one of the preceding claims, wherein each of said tanks is equipped with a pressure sensor and / or a level sensor.

20. Device (10, 1 10, 210) according to one of the preceding claims, wherein the or each buffer tank is located below an upper end of said main tank.

21. Device (10, 1 10, 210) according to one of the preceding claims, wherein the or each buffer tank is located outside said main tank.

22. Device (10, 1 10, 210) according to one of the preceding claims, wherein the or each buffer tank may have an expansion function and / or separation.

23. Device (10, 1 10, 210) according to one of the preceding claims, wherein said main reservoir is of the membrane type.

24. Device (10, 1 10, 210) according to the preceding claim, wherein said main tank is configured to withstand a pressure of less than or equal to 3000 mbar, and preferably less than or equal to 750 mbar.

25. Ship, in particular liquefied gas transport, comprising at least one device (10, 1 10) according to one of the preceding claims.

26. A method for supplying fuel to a power generation installation (12), in particular on a ship (14), by means of a device (10) according to one of the preceding claims, characterized in that what he understands: a step A of filling said first buffer tank (18), creating a depression in said first buffer tank (18) with respect to said main tank (16), so that liquefied gas is transferred from the main tank (16); ) to the first buffer tank (18).

27. Method according to the preceding claim, the device being as defined in claim 5, comprising:

a step B1 of supplying said installation (12) by means of said compressor (20) by suction of gas into said first buffer tank (18).

28. The method of claim 26 or 27, the device (10) being furthermore as defined in claim 17, comprising:

a step B2 supplying said installation (12) by means of said compressor (20) by supplying gas to said first and / or second buffer tank (18, 40) to force liquefied gas to flow in said first line (32); ).

29. Method according to the preceding claim, wherein, in step B1 or B2, said second buffer tank (40) is supplied with liquefied gas by creating by means of said compressor (20) a vacuum in said second buffer tank (40). ) with respect to said main tank (16), so that liquefied gas is transferred from the main tank (16) to the second buffer tank (40)

30. Method according to one of claims 26 to 29, wherein, during step A, the pressure inside said main tank is controlled by regulating the flow of gas flowing in said fourth pipe and / or in said fifth drive.

31. The method of one of claims 26 to 30, wherein in step A or after step A, the pump of said first conduit is supplied with liquefied gas from said first buffer tank.

32. Method according to one of claims 26 to 31, wherein, it comprises a step B3 supplying said installation via said first pipe, by actuating said pump.

33. Method according to one of claims 26 to 32, wherein, in step A, the depression is maintained continuously for a predetermined period.

34. Method according to one of claims 26 to 33, wherein the vacuum is achieved by applying a pressure difference between said buffer tank (18) and said main tank (16), which is greater than a hydrostatic pressure generated by a substantially rectilinear and vertical height of said second pipe, possibly with a deduction of pressure drops in this second pipe.

35. Method according to one of claims 26 to 34, wherein said pump is controlled according to a fuel gas requirement of said installation.

36. Method according to one of claims 26 to 35, wherein at least some valves that equip one or more of said pipes are controlled according to a fuel gas requirement of said installation.

37. Method according to one of claims 26 to 36, wherein the pressure difference between the buffer tank and the main tank is increased, in order to increase the supply flow rate of liquefied gas buffer tank, as soon as the level liquefied gas in the buffer tank is below a certain threshold level.

38. Method according to one of claims 26 to 37, wherein the pressure difference between one of the buffer tanks and the main reservoir is adjusted according to the filling speed of the other buffer tanks, by liquefied gas from of said main tank.

39. A method according to one of claims 26 to 38, wherein liquefied gas contained in said first buffer tank is conveyed by said first and sixth lines to said spray boom.