JP2020519828A - Apparatus and method for supplying fuel to a power generation facility - Google Patents

Abstract

The invention relates to a device (10, 110, 210) for supplying a fluid fuel, in particular to a power generation facility (12) mounted on a ship (14), comprising a main tank (16) of liquefied gas and at least A first liquefied gas first buffer tank (18) and a first pipe (32) for transferring liquefied gas from the first buffer tank to the facility (12), the first pipe (32) One end (32a) opens into the first buffer tank (18) and the second end (32b) of the first pipe (32) supplies the facility with fluid fuel. A first pipe (32) connected to the first pipe (32) and a second pipe (22) for transferring a liquefied gas from the main tank (16) to the first buffer tank (18). A first end portion (22a) intended to be immersed in the liquefied gas (24) contained in (1) and a first buffer tank (18) for supplying the liquefied gas to the first buffer tank. A second pipe (22) having an open second end (22b) and means (20, 36) for decompressing the first buffer tank (18) with respect to the main tank (16). Means (20, 36) comprising at least one compressor (20) configured to apply an operating pressure below atmospheric pressure to the first buffer tank (10, 110). , 210).

Description

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

The prior art includes, inter alia, documents WO-A1-2012/089891 and WO-A1-2015/183966.

In order to more easily transport a gas such as natural gas over a long distance, the gas is liquefied by cooling to a cryogenic temperature at atmospheric pressure, for example, to -163° C. (which is liquefied natural gas (LNG). To)). After that, the liquefied gas is carried into the special ship.

For example, a methane tanker type ship for transporting liquefied gas is provided with energy production equipment to meet the energy demands of the operation of the ship, especially the propulsion of the ship and/or the production of electricity for onboard equipment. There is.

This type of installation typically includes a thermomechanical that consumes gas from an evaporator powered by a cargo of liquefied gas that is transported to the tank or tanks of the vessel.

Document FR-A-2 837 783 defines power supply to this type of evaporator and/or other systems necessary for propulsion with a pump submerged in the bottom of the tank of a ship.

Pumps arranged in this way have drawbacks. According to the IACS (International Association of Classification Societys) code, pumps must be inspected on a regular basis. Inspection of the pump requires the main tank to be opened, so the ship may be stationary and may damage the tank.

The solution to this problem is to provide an opening in the bottom of the tank and to discharge the liquefied gas from the main tank through this opening. However, the IGF and IGC Codes (International Regulations on the Structure and Equipment of Ships for Bulk Transport of Liquefied Gases) prohibit such openings in large capacity tanks, such as in the case of the main tank of a ship.

The present invention proposes a simple, effective and economical improvement over the current state of the art.

The present invention is
In particular, a device for supplying a fuel fluid to a power generation facility mounted on a ship,
-Main liquefied gas tank,
-At least one first liquefied gas buffer tank,
A first pipe for transferring a fluid or a liquefied gas from the first buffer tank to the installation, the first end of the first pipe opening into the first buffer tank, the first pipe A second end of the first pipe connecting to the facility for supplying fuel fluid to the facility;
A second pipe for transferring liquefied gas from the main tank to the first buffer tank, the first end intended to be immersed in the liquefied gas housed in the main tank; A second pipe having a second end opening into the first buffer tank to supply liquefied gas to the first buffer tank;
-Means for lowering the pressure in the first buffer tank with respect to the main tank, sucking the fluid in the first buffer tank, and in the first buffer tank, Means adapted to transfer a liquefied gas from the main tank through the second pipe to supply the first buffer tank by applying a low operating pressure;
In a device including
The pressure reducing means includes at least one compressor,
A device is proposed, characterized in that the operating pressure is preferably below atmospheric pressure.

The device according to the invention thus addresses the problems of the prior art. Here, the pump immersed in the main tank is not essential for sending the liquefied gas from the main tank to the buffer tank. The reduced pressure in the buffer tank, that is, the pressure difference between the buffer tank and the main tank may cause the buffer tank to supply the liquefied gas contained in the main tank. Therefore, the liquefied gas flows from the main tank to the buffer tank in the second pipe. The BOG housed in the main tank can be conventionally used to supply the equipment of a ship. Here, the device makes it possible to add to this BOG source an additional fluid which is available in the gas or liquid state in the buffer tank and which can be sent to the installation by means of the first pipe.

The first buffer tank may have a pressure reduced to a pressure lower than atmospheric pressure (for example, −600 mbar or more and −100 mbarg or less, or −600 mbarg or more and −200 mbarg or less). Even if the buffer tank has a pressure close to atmospheric pressure, for example, -100 mbar or more and 100 mbarg or less, or -100 mbarg or more and 250 mbarg or less, or -s 100 mbarg or more and 400 mbarg or less, the liquefied gas is transferred from the main tank to the buffer tank. The compressor can produce this kind of pressure drop.

This allows, for example, an immediate supply of gas to equipment including a motor, while the prior art requires waiting until the pressure in the main tank rises to a level sufficient to supply the motor. There is. Furthermore, it should be noted that in this case the pressure must be at a level compatible with the motor, for example above 6 barg, and that the tank and especially the tank type can be selected depending on its pressure resistance.

The device according to the invention has one or more of the following features, either individually or in combination with one another.
-The main tank is a membrane type. That is, its wall, in particular its inner wall, comprises at least one metal layer forming a sealing membrane and at least one heat insulating layer.
The main tank is configured to withstand a pressure of 3000 mbarg or less, preferably 750 mbarg or less.
The main tank is of the membraneless type.
The main tank is configured to withstand a pressure of 3000 mbarg or higher, preferably 6000 mbarg or higher.
The pressure reducing means has an outlet intended to connect to the installation.
-The pressure reducing means comprises at least one compressor.
A pump is arranged to connect to the first pipe and to suck liquefied gas from the first buffer tank.
-The compressor is connected to a third pipe so as to reduce the pressure in the first buffer tank, the first end of the third pipe opening into the first buffer tank, The second end is connected to the inlet of the compressor, and the third pipe is configured to suck the boil-off gas in the first buffer tank and supply the boil-off gas to the compressor.
-The compressor has an outlet connecting to the facility for supplying fuel gas to the facility.
The second end of the third pipe is connected to the compressor by a first circuit of a heat exchanger.
The device comprises a fourth pipe for transferring gas from the main tank to the compressor.
-The fourth pipe has a first end opening to the main tank and a second end connecting to the compressor.
The second end of the fourth pipe is connected with the second pipe to the inlet of the first circuit of the heat exchanger, the outlet of the heat exchanger being connected to the compressor.
-The first end of the second pipe does not have a pump.
-The first pipe comprises at least a pump, and/or a pressure reducing valve, and/or a heat exchanger. The heat exchanger may be configured to vaporize the liquefied gas flowing through the first pipe to supply the fuel gas to the facility.
-The pump is arranged to be controlled according to the fuel gas demand of the installation.
-The device comprises a fifth pipe for returning fluid from the decompression means to the main tank, the first end of the fifth pipe being connected to the outlet of the decompression means, Two ends open to the main tank.
-The device comprises a second liquefied gas buffer tank.
-The second buffer tank is
A first pipe that is the first pipe and has a third end that opens into the second buffer tank;
A second pipe having the third end opening to the second buffer tank, which is the second pipe;
Connect to.
-The second buffer tank is connected to the third pipe, the third pipe having a third end opening into the second buffer tank.
-The device comprises a fifth pipe for supplying gas to the first buffer tank and the second buffer tank, the first end of the fifth pipe being connected to the outlet of the pressure reducing means, The second end of the fifth pipe opens into the first buffer tank, the third end of the fifth pipe opens into the second buffer tank, and the fifth pipe opens into the first buffer tank. And/or is configured to supply compressed gas to the buffer tank.
-The first pipe is connected by a sixth pipe to a manifold for spraying liquefied gas into the main tank, and the manifold sprays liquefied gas in a droplet state onto boil-off gas in the main tank. It is configured to condense at least a portion of the boil-off gas.
-Each tank is provided with a pressure sensor and/or a level sensor.
-The or each buffer tank is arranged below the upper end of the main tank.
-The or each buffer tank is arranged outside the main tank.
-The or each buffer tank may have expansion and/or separation functions. At least a part of the liquefied gas supplied to the buffer tank may be partially evaporated and phase-separated in the tank. Less than half, or less than 10% of the aspirated liquefied gas can thus be evaporated. The gas outlets in liquid and gaseous form can be connected to the installation without passing through the main tank or again. Since a small part (1% to 10%) of the extracted LNG evaporates in the upstream of the compressor, a compressor having a small flow rate can be used. In fact (for gas LNG demand with energy production facilities), less suction is needed than if only gas was sucked in (gas volume is approximately 600 times liquid volume).
-The gas comprises at least one pure substance or gas.
For example,
-The first pipe transfers (in liquid form) at least part of the pure gas and optionally other gases from the buffer tank to the facility, and/or
-The compressor draws at least a portion of the pure gas, optionally mixed with other gases, and/or
-The compressor supplies the facility with pure gas (optionally mixed with other gases).

As used herein, “pure” refers to a single chemical species or substance with respect to a mixture of substances or species. The pure gas is, for example, a light gas or a heavy gas.

In the present application, heavy gas and light gas respectively mean a heavy gas, ie a gas with a high molar volume, and a light gas, ie a gas with a low molar mass. In the liquefied gas, the light gas is generally methane. In the liquefied gas, the light fraction may contain a small amount of nitrogen. Smaller heavy fractions include, for example, in the case of liquefied gases, propane, butane and ethane (thus it evaporates at higher temperatures or lower pressures). In the liquefied gas, the heavy gas corresponds to 5.2% to 49.8% of the total mass of the liquefied gas. The heavy gas has, for example, a molar mass that is 25% to 500% greater than the molar mass of the light gas.

The invention further relates to a ship, in particular for transporting liquefied gas, comprising at least one device as described above. The invention has particular application to LNG-propelled vessels, which are a special case of vessels for transporting liquefied gas, where the propulsion tank is also considered to have a transport function.

The present invention further comprises
In particular, a method for supplying fuel to an energy production facility mounted on a ship by the above-mentioned device,
-A step A of transferring liquefied gas from the main tank to the first buffer tank by lowering the pressure in the first buffer tank with respect to the main tank, and filling the first buffer tank;
And a method comprising:

The method according to the invention may comprise or have one or more of the following steps, or one or more of the following features, either separately from one another or in combination with one another.
The method comprises a step B1 of sucking the gas in the first buffer tank by the compressor to supply it to the installation.
-In step B1, the equipment is supplied by the compressor by taking in gas in the main tank and the first buffer tank.
-The method comprises a step B2 of supplying the equipment by supplying gas to the first and/or second buffer tanks by the compressor to force liquefied gas to flow through the first pipe. ..
-In step B1 or B2, the liquefied gas is transferred from the main tank to the second buffer tank by lowering the pressure in the second buffer tank with respect to the main tank by the compressor, and the second buffer Supply liquefied gas to the tank.
-In step A, the pressure in the main tank is controlled by adjusting the flow rate of the gas flowing through the fourth pipe and/or the fifth pipe.
-In or after step A, the pump of the first pipe is supplied with liquefied gas from the first buffer tank.
The method comprises a step B3 of supplying the equipment via the first pipe by operating the pump.
-In step A, the reduced pressure is continuously maintained for a predetermined time.
-The hydrostatic pressure generated by the substantially linear vertical height of the second pipe, which is the pressure difference between the buffer tank and the main tank, and where necessary the head loss in the second pipe is subtracted. The pressure is reduced by applying a larger pressure difference.
-The pump is controlled according to the fuel gas demand of the installation.
-At least some valves provided in one or more of the pipes are controlled according to the fuel gas demand of the installation.
-As soon as the liquefied gas level in the buffer tank falls below a predetermined threshold level, the pressure difference between the buffer tank and the main tank is immediately increased to increase the flow rate of the liquefied gas supplied from the buffer tank. Let
The pressure difference between one of the buffer tanks and the main tank is adjusted according to the rate at which the other buffer tank is filled with liquefied gas from the main tank.
-The liquefied gas stored in the buffer tank is sent to the spray manifold by the first and sixth pipes.

The invention will be better understood and further details, features and advantages of the invention will emerge more clearly on reading the following description, given by way of non-limiting example, with reference to the accompanying drawings, in which:

1 is a schematic view of an apparatus according to a first embodiment of the present invention, which is installed in a ship. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 3 is a schematic view of an apparatus according to a second embodiment of the present invention, which is installed in a ship. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 6 is a schematic view of an apparatus according to a third embodiment of the present invention, which is mounted on a ship.

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

FIG. 1 shows a device 10 according to a first embodiment of the invention. The device 10 is assumed to be capable of supplying fuel gas to a ship such as a ship that transports liquefied gas. Accordingly, the apparatus 10 may be used to supply fuel gas to an energy production facility 12 on board a vessel 14.

The vessel 14 includes a single tank 16 or a plurality of similar tanks 16 for storing liquefied gas. The gas is, for example, methane or a gas mixture containing methane. The tank 16 or each tank 16 may contain a gas in a liquefied state at a predetermined pressure and a predetermined temperature, for example, atmospheric pressure and a temperature of about −163° C. The tank(s) 16 of the vessel may be connected to the installation 12 by means of the device 10 according to the invention. Therefore, the number of tanks is not limited to the present invention and is, for example, 1 or more and 6 or less. Each tank 16 may have a capacity of 1000 (or 100) ^{m 3} to 50000 m ^3.

Hereinafter, the expression "tank 16" should be construed as meaning "tank 16 or each tank 16".

The tank 16 contains the liquefied gas 16aa and the gas 16ab generated from the boil-off (evaporation) of the liquefied gas 16aa in the tank 16, especially natural boil-off. The liquefied gas 16aa is naturally stored at the bottom of the tank 16, whereas the boil-off gas 16ab is located above the level (height) of the liquefied gas in the tank, which is schematically represented by the letter N.

In the following, "LNG" means liquefied gas, that is, liquid state gas, "BOG" means boil-off gas, "NBOG" means natural boil-off gas, and "FBOG" means forced boil-off gas. And These abbreviations correspond to the first letter of the relevant English word and are known to those skilled in the art.

In the embodiment shown in FIG. 1, the end 22a of the pipe 22 is immersed in the LNG 16aa in the tank 16. Preferably, there is no pump at this end so that no maintenance is required. The end is preferably located at the bottom of the tank, which ensures that the pipe is only supplied with liquid LNG, even if the tank is almost empty.

In the present application, the "bottom" of a tank means a position that is less than 1 meter from the bottom wall of the tank. This bottom wall is the wall of the tank that is closest to the center of the earth during operation.

The pipe 22 includes a branch connection and has two ends located outside the tank 16. One end 22d forms a port for filling the tank 16 with LNG, which is accessible to the user, especially when LNG is loaded into the tank of the vessel.

The other end 22b of the pipe is connected to the buffer tank 18, which is also located outside the tank 16. The valves 23d and 23b are associated with the ends 22d and 22b, respectively. The valve 23d can block the flow of fluid in the pipe 22 and thus the supply of LNG to the tank 16. The valve 23d may form a check valve. The valve 23b can block the supply of fluid to the buffer tank 18, especially during refueling of the main tank 16.

A manifold 52 for spraying LNG droplets is located above the level N at the top of the tank 16. Therefore, the manifold 52 is configured to spray LNG droplets onto the BOG in the tank. As a result, the BOG in the tank 16 can be forcibly recondensed.

The tank 16 further includes a BOG inlet 16a and a BOG outlet 16b. The outlet 16b is connected to one end 30a of the pipe 30. The pipe 30 also includes a branch connection that defines two ends located outside the tank 16. One end 30c forms a port for discharging BOG from the tank 16. The end 30c is accessible to the user, especially when loading LNG into the tank 16 of a ship.

The other end 30b of the pipe 30 is connected to the inlet 28aa of the first circuit 28a of the heat exchanger 28. The outlet 28ab of the first circuit 28a of the heat exchanger 28 is connected to the inlet 20a of the compressor 20. The first circuit 28a is a cold circuit and it is intended that the fluid flowing through the circuit 28a is heated by the second circuit 28b of the exchanger 28, ie the fluid flowing through the hot circuit.

Valves 31a, 31c are associated with each end 30a, 30c. The valve 31a can block the flow of fluid through the pipe 30, and thus the discharge of the BOG from the tank 16. The valve 31a may form a check valve. The valve 31c can block exhaust to the end 30c of the BOG and the corresponding port.

The inlet 16a of the tank 16 is connected to one end 38b of the pipe 38. The other end 38a of the pipe 38 connects to the outlet 20b of the compressor 20. A valve 39 is associated with the pipe 38 and blocks the passage of fluid from the outlet of the compressor 20 to the tank 16. The outlet 20b of the compressor 20 is further connected to the facility 12 by a valve 41.

The buffer tank 18 includes 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 and the buffer tank 18 is intended to be supplied with LNG coming directly from the tank 16.

The outlet 18b is an outlet for gas which is especially BOG, and the outlet 18c is an outlet for LNG. The outlet 18b is connected to one end 26a of the pipe 26. The opposite ends 26b of the pipes 26 are connected to the inlet 20a of the compressor 20. In the illustrated example, the BOG exiting the buffer tank 18 is preheated by the exchanger 28 before being supplied to the compressor 20. For this purpose, the pipe 26 is connected to the pipe 30 upstream of the exchanger 28 and more specifically upstream of the circuit 28a. This allows BOG coming from both tank 16 and buffer tank 18 to be fed to circuit 28a and heated prior to being fed to compressor 20.

The pipe 26 comprises a valve 27 capable of blocking the passage of fluid in the pipe 26, in particular the discharge of BOG from the buffer tank 18 to the exchanger 28.

The outlet 18c is connected to one end 32a of the pipe 32. The pipe 32 is connected to the facility 12 at the outlet 20b of the compressor 20. This pipe 32 includes or is connected to a pump 36 and is connected to a heat exchanger 34. The pipe 32 further includes two valves 33a, 33b including, for example, a pressure reducing valve 33b. In the illustrated example, the pump 36, the valve 33b, the exchanger 34, and the valve 33a are arranged from the upstream side to the downstream side, that is, from the tank 18 toward the outlet 20b of the compressor 20.

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

In the illustrated example, LNG discharged from the buffer tank 18 by the pump 36 is evaporated in the exchanger 34 before being supplied to the facility 12. For this purpose, the pipe 32 is connected to the inlet 34aa of the first circuit 34a of the heat exchanger 34. The outlet 34ab of the heat exchanger 34 is connected to the valve 33a. The first circuit 34a is a cold circuit and it is intended that the fluid flowing through the circuit 34a is heated by the fluid flowing through the second circuit of the exchanger 34, the hot circuit 34b.

If the valve 33b is a pressure reducing valve and all LNG can be evaporated as FBOG, the FBOG may be heated by the exchanger 34 before being supplied to the facility 12. Therefore, the valve 33b is advantageously configured to match the pressure at the outlet of the FBOG with the pressure at which the fuel gas is used in the facility 12.

A spray manifold 52 is connected to the pipe 32 by a pipe 50 provided with a valve 51. Its upstream end is connected to the pipe 32 between the pump 36 and the valve 33b, ie just downstream of the pump 36. Also, its downstream end is connected to the manifold 52. Therefore, as described above, it is clear that the LNG housed in the buffer tank 18 can be supplied to the spray manifold 52.

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 pressure at which LNG is stored in the tank 16. Therefore, when LNG is supplied to the buffer tank 18, the LNG is partially evaporated, FBOG is generated in the buffer tank 18 reflecting this, and the remaining LNG in the buffer tank 18 is cooled. This is called "subcooled liquefied gas". The buffer tank 18 stores a liquid-shaped gas having a predetermined pressure and a predetermined temperature.

Therefore, the buffer tank 18 contains the subcooled liquefied gas 18aa and the boil-off of the liquefied gas 16aa from the tank 16, here the gas 18ab generated by the forced boil-off. The subcooled liquefied gases (LNGs) 18aa are naturally stored at the bottom of the buffer tank 18, whereas the boil-off gas (ie FBOG) 18ab is the liquefied gas in the buffer tank 18 represented schematically by the letter L. Located above the level.

Here, the compressor 20 is used to apply an operating pressure in the buffer tank 18. Therefore, it is configured to reduce the pressure in the buffer tank 18 against the tank 16. The pressure differential between them may be sufficient to force LNG from tank 16 into buffer tank 18. Therefore, in the latter case, it is clear that the immersion pump at the end 22a of the pipe 22 is unnecessary. The conditions imposed on the buffer tank 18 by the compressor 20 are determined to produce LNGs within the buffer tank 18.

Alternatively or additionally, pump 36 may be configured to help reduce the pressure in buffer tank 18 relative to main tank 16.

If the amount of LNGs in buffer tank 18 becomes too high to reach a threshold level, LNGs may be transferred from the LNGs outlet of buffer tank 18 to spray manifold 52 in facility 12 and/or tank 16.

LNGs provide cooling power. When the cooling power is unnecessary, for example, the cooling power can be stored in the buffer tank 18 in a phase in which the amount of NBOG generated is insufficient to satisfy the demand amount.

In the illustrated example, the pressure drop in tank 18 may allow LNG to flow through pipe 22. Pipe 22 includes a vertical portion that forms a dip tube that is dipped in LNG in tank 16. Its upper end is connected to the rest of the pipe 22 by a tee. The pressure difference between the two tanks 16, 18 is preferably the height of the pipe 22 less head loss in the pipe 22 (more precisely the height of the vertical portion of the pipe 22 up to the tee above the bottom of the tank). ) Must be greater than the hydrostatic pressure created by (if tank 16 is empty, LNG must be able to be raised to this height). Alternatively, if the tank 18 (more precisely the outlet 22b) is below this height and the pipe 22 is primed (when the tank 16 is almost full, for example by a smaller pressure difference), the pressure difference will be smaller. Good.

The pressure difference can be adjusted by the following method.
-Control the pump 36 according to the gas demand of the facility 12 (the gas demand is determined, for example, by the difference between the set value of the facility 12 and the flow rate of the gas measured between the outlet 32b and the facility 12). Be done).
The tank 18 has a level sensor. When the level in the tank 18 falls below the lower threshold, the pressure difference is immediately increased to increase the flow rate to the tank 18 (also the upper threshold level is provided to reduce the pressure difference immediately upon reaching that level). Or it may be offset).

The fuel gas supply device has two main functions described below.
-The fuel gas is supplied from the main tank 16 to the equipment of the ship at a desired flow rate (for example 50 kg/h to 2000 kg/h), a predetermined pressure (for example 6 bar to 300 bar), and a predetermined temperature (for example 20°C). The fuel gas may have a gas form (vapor) or a liquid form.
-Adjust the pressure in the main tank 16 within an acceptable range (e.g. -100 mbarg to +700 mbarg, or -700 mbarg to 6000 mbarg).

The described apparatus 10 is, for example, designed to contain a cryogenic liquid at atmospheric pressure (eg, a capacity of 1000 m ³ (or 100 m ³ ) to 10000 m ³ and a licensed pressure of −100 mbar to +700 mbarg or −700 mbarg to 6000 mbarg). And a buffer tank 18 intended to contain a cryogenic liquid (for example having a capacity of 1 m ^{3 to} 20 m ³ and an allowable pressure of −500 mbar to 6000 mbar). A compressor 20 and/or pump 36 allows a pressure differential between the main tank 16 and the buffer tank 18 (e.g. +500 mbar). The liquid in the buffer tank 18 is compressed by the pump 36 and sent to the facility 12 via the evaporation valve 33b. The level of liquid in the buffer tank 18 is controlled using suitable equipment, for example 10% to 90% of the capacity of the buffer tank. In this way, the pump 36 is always supplied with 100% liquefied gas (a mixture of natural gas in the gas and liquid states can damage the pump). The method of controlling the device and the appropriate equipment are designed such that the pressure in the main tank 16 is maintained at the required level (eg, -100 mbarg to 700 mbarg). Therefore, advantageously, each tank of the device 10 is provided with a pressure sensor and/or a level sensor.

2 to 6 show the phases of operation of the device of FIG. These operating phases may correspond to the operating phases of a ship equipped with the device.

The supply method will be described in the following three phases.
1. Minimum Consumption: Natural boil-off covers the energy needs of the facility (the ship's propulsion engine is off or operating at low load, gas is used primarily to meet electricity and heating needs). ).
2. Normal consumption: Natural boil-off does not cover the ship's energy needs.
3. No consumption (all gas consuming elements mounted on the facility 12 except the gas compressor are stopped).
4. filling.

1. Minimum consumption (see Figure 2)

In the operation phase shown in FIG. 2, the main engine of the ship is stopped and the power consumption is less than the maximum capacity of the compressor 20 (<2 to 3 MW).

The pressure of the BOG 16ab in the tank 16 rises due to the evaporation of the LNG 16aa in the tank 16. The BOG 16ab is sucked by the compressor 20, heated by the exchanger 28, and sent to the facility 12. This allows the pressure in tank 16 to be maintained below an acceptable threshold.

The following operations are possible to adjust the pressure in the tank 16.
Adjusting the flow rate of the BOG sent to the compressor 20 (if the flow rate is higher than the natural boil-off speed, the pressure in the tank 16 drops; if the flow rate is lower than the natural boil-off speed, the pressure in the tank rises).
Re-inject some of the compressed gas (exiting the compressor 20) into the main tank 16 (e.g. due to the specifications of the compressor 20 the input flow rate of the compressor is reduced below a certain value (here greater than the natural boil-off speed)) If this is not possible, some of the compressed gas is reinjected into the tank 16 via the pipe 38 and the pressure in the tank 16 is adjusted.

Thus, the device 10 supplies the required amount to the facility 12 with the gas coming from the tank 16 and maintains the pressure inside the tank at the required level (e.g. -100 mbarg to 700 mbarg).

2. Normal consumption

In the second phase of operation, consumption is normal.

The natural boil-off in tank 16 is insufficient to meet the energy demand of facility 12. Forced boil-off is required to meet the ship's energy needs. This phase includes the following two steps.
-Preparation for forced boil-off: Fill the buffer tank 18 and pump 36 with liquefied natural gas.
-Forced evaporation: the liquid from the buffer tank 18 is forcibly evaporated and sent to the facility.

-Preparation for forced evaporation (Fig. 3)

The first step is to reduce the pressure in the buffer tank 18 and/or increase the pressure in the tank 16 to create a pressure difference between the main tank 16 and the buffer tank 18 of, for example, -500 mbar. Become. As mentioned above, the pressure in tank 16 may be increased by reinjecting compressed BOG into it. The pressure in the buffer tank 18 can be lowered by sucking the natural gas in the buffer tank by the compressor 20. Due to this pressure difference, the LNG accommodated in the tank 16 can be sucked from a height of 10 m.

When the pressure rises in the tank 16, the BOG accommodated in the tank 16 tries to push the LNG out of the tank 16, so that the LNG is forced to flow through the pipe 22 to the buffer tank 18. When the pressure in the buffer tank 18 decreases, LNG is sucked from the tank 16 into the buffer tank 18. The pressure difference contributes to partial (flash) evaporation and formation of BOG in the buffer tank 18. The BOG is sucked by the compressor 20 and the pressure difference between the tanks 16 and 18 is maintained.

The second step is to fill pump 36 with liquefied natural gas. When the buffer tank 18 is filled to the required level with liquefied natural gas, for example 90% of its capacity, LNGs are fed to the pump 36 by gravity. Pump 36 must be completely filled with liquid. This is because otherwise bubbles could be generated which could damage the pump. The LNGs flow in the pipe 32 to the pump 36 and pass therethrough. Leave the pump closed.

These operations may be combined with the first operation phase to adjust the pressure in the main tank 16.

-Forced evaporation (Fig. 4)

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

LNG from the buffer tank 18 is sent to the facility 12 via the exchanger 34. The flow rate of LNGs sent to the facility 12 is adjusted by the pump 36. The facility 12 prioritizes receiving gas from the compressor 20 (which manages the pressure in the tanks 16, 18) and obtains make-up gas by the pump 36. The make-up gas is used to flow LNG through valve 33b to vaporize, preferably to completely vaporize LNG prior to heating in exchanger 34. As described above, LNG is supplied to the buffer tank 18 by lowering the pressure in the tank 18 with respect to the tank 16. The outflow of LNG from the buffer tank 18 is adjusted by the pump 36. The level of LNG in the buffer tank 18 is adjusted to be maintained at a required level, for example 10% to 90% of its capacity.

These operations may be combined with the first operation phase to adjust the pressure in the main tank 16.

3. No consumption (see Figure 5)

This operating phase is activated in an emergency. The facility 12 is stopped. That is, there is no consumption of fuel gas. The exchanger 28, the compressor 20, and the pump 36 are operated by an emergency generator.

In this phase, it is assumed that the tanks 16 and 18 contain LNG. The pump 36 allows LNG to flow from the buffer tank 18 to the manifold 52. Due to the pressure difference between the tanks 16 and 18, the LNG continues to flow from the tank 16 to the buffer tank 18 and boil off in the latter. This means that the LNG formed in the buffer tank 18 is subcooled compared to the LNG housed in the tank 16. The subcool liquefied gas from the buffer tank 18 is supplied to the manifold 52, and the manifold 52 sprays droplets of the gas onto the BOG in the tank 16. As a result, the BOG in the tank 16 can be condensed, so that the pressure reduction and the pressure maintenance in the main tank 16 are realized.

Therefore, the pressure in the tank 16 is regulated by the flow of LNG coming from the buffer tank 18 and sprayed by the manifold 52. This operating phase may be combined with the first or second phase to reduce the pressure in the main tank 16.

4. Filling (see Figure 6)

The valve 23d is opened. LNG from the filling station is sent to tank 16. BOG boiled off during filling is drained by opening valves 31a and 31c, forming a free flow of BOG to the station.

FIG. 7 shows a device 110 according to a modified embodiment of the invention. This variant embodiment differs from the device 10 in particular in that it comprises two buffer tanks 18 and 40.

The features described above with reference to device 10 apply to device 110 unless they are inconsistent with the description below.

The pipe 22 is connected to each of the tanks 18 and 40, and has an end 22b connected to the LNG inlet 18a of the tank 18 and an end 22c connected to the LNG inlet 40a of the tank 40. In addition to the valves 23b and 23d of the pipe 22, valves 23e and 23f are associated with the ends 23b and 23d, respectively.

Here, each buffer tank 18, 40 includes four ports, namely two inlets 18a, 40a, 18d, 40d and two outlets 18b, 40b, 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 is intended to be supplied with LNG coming directly from the tank 16.

The outlets 18b, 40b are outlets for gas, in particular BOG, and the outlets 18c, 40c are LNG outlets. The outlets 18b and 40b are connected to the respective ends 26a and 26c of the pipe 26. The opposite end 26b of the pipe 26 is connected to the inlet 20a of the compressor 20 or, as mentioned above, to the inlet 28aa of the circuit 28a of the exchanger 28.

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

Another pipe 42 connects the outlet 20b of the compressor 20 to the tank inlets 18d, 40d. The inlets 18d, 40d are the inlets for the compressed gas or BOG, as the compressed BOG may be supplied to the tanks 18, 40, as described in more detail below. The pipe 42 includes a valve 43 that blocks the passage of fluid from the outlet of the compressor 20 to the tanks 18, 40. Further, each inlet 18d, 40d is associated with a valve that allows the tanks to be isolated from each other.

The outlets 18c, 40c of the tanks 18, 40 are connected to the ends 32a, 32c of the pipe 32 connected to the outlet 20b of the compressor 20. This pipe 32 includes or is connected to a heat exchanger 34. The pipe further comprises two valves 33a, 33b, one of which is, for example, a pressure reducing valve 33b. In the illustrated example, the valve 33b, the exchanger 34, and the valve 33a are arranged in the direction from upstream to downstream, that is, from the tanks 18, 40 toward the outlet 20b of the compressor 20. Valves are further associated with each outlet 18c, 40c.

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

In the illustrated example, the LNG discharged from the buffer tank 18 is preheated by the exchanger 34 before being supplied to the facility 12. For this purpose, the pipe 32 is connected to the inlet 34aa of the first circuit 34a of the heat exchanger 34 and the outlet 34ab of the first circuit 34a is connected to the valve 33a. The first circuit 34a is a low temperature circuit, and it is intended that the fluid flowing through the circuit 34a is heated by the second circuit 34b of the exchanger 34, that is, the fluid flowing through the high temperature circuit.

If the valve 33b is a pressure reducing valve and it is possible to vaporize all LNG to form the FBOG, the FBOG may be heated by an exchanger before being supplied to the facility 12. Therefore, the valve 33b is advantageously configured to match the pressure at the outlet of the FBOG with the pressure at which the fuel gas is used in the facility.

The pipe 50 connects the spray manifold 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 manifold 52. Therefore, as described above, it is clear that the LNG housed in the buffer tanks 18, 40 can be supplied to the spray manifold 52.

In the illustrated example, the pressure drop in tank 18 must allow LNG to flow through pipe 22. The pipe 22 has a vertical section that forms a dip tube that is dipped in the LNG in the tank 16. Its upper end is connected to the rest of the pipe 22 by an elbow. The pressure difference between the two tanks 16, 18 is preferably the height of the pipe 22 less the head loss in the pipe 22 (more precisely the height of the vertical part of the pipe 22 from the bottom of the tank to the elbow). -Since the tank 16 is empty, the LNG must be able to be pulled up to this height) and must be greater than the hydrostatic pressure generated by. Alternatively, if the tank 18 (more precisely the outlet 22b) is below this height and the pipe 22 is primed (when the tank 16 is almost full, for example by a smaller pressure difference), the pressure difference will be smaller. Good.

The pressure difference can be adjusted by the following method.
Controlling the valves corresponding to the outlets 18c, 40c of the tanks 18, 40 according to the gas demand of the facility 12.
-Adjust the pressure difference so that these buffer tanks are filled fast enough (thus the difference depends on the gas demand of the installation 12).

Each tank 18, 40 functions similarly to tank 18 of device 10. Furthermore, the tanks 18, 40 have a supplementary function by being connected to the outlet 20b of the compressor 20. The compressed BOG leaving the compressor 20 and supplied to the tanks 18, 40 can pressurize these tanks 18, 40 and force the LNG 18aa, 40aa through the outlets 18c, 40c. Therefore, it is not necessary to provide a pump such as the pump 36 of the device 10 at these outlets to force LNG out of the buffer tanks 18, 40.

The fuel gas supply device has two main functions described below.
-The fuel gas is supplied from the main tank 14 to the equipment 12 of the ship at a desired required flow rate (for example, 50 kg/h to 2000 kg/h), a predetermined pressure (for example, 6 bar to 300 bar), and a predetermined temperature (for example, 20°C). .. The fuel gas may have a gas form (vapor) or a liquid form.
-Adjust the pressure in the main tank 16 within an acceptable range (e.g. -100 mbarg to +700 mbarg).

The described apparatus 10 comprises, for example, a main tank 16 designed to contain a cryogenic liquid at atmospheric pressure (for example having a capacity of 1000 m ^{3 to} 10000 m ³ and an approved pressure of −100 mbarg to +700 mbarg) and a cryogenic temperature. A buffer tank 18 intended to contain a liquid (for example having a capacity of 1 m ^{3 to} 20 m ³ and an allowable pressure of −500 mbar to 6000 mbar). The compressor 20 has a pressure difference between the main tank 16 and the buffer tanks 18, 40 so that the liquid can be transferred from the main tank 16 to the buffer tanks 18, 40 (for example, +500 mbarg for the main tank with respect to the buffer tank). Cause The liquid in the buffer tanks 18 and 40 is sent to the facility 12 via the boil-off valve 33b. The level of liquid in each buffer tank is controlled using suitable equipment, for example 10% to 90% of the capacity of the buffer tank.

The manner in which the device is controlled, and the appropriate equipment, is designed to maintain the pressure in the main tank 16 at the required level (eg, -100 mbarg to 700 mbarg). Thus, advantageously, each tank of the device 110 is provided with a pressure sensor and/or a level sensor.

8 to 12 show the operating phases of the device of FIG. These operating phases may correspond to the operating phases of a ship equipped with the device.

The liquefied gas cooling method will be described in the following four operating phases.
1. Minimum consumption: Natural boil-off covers the energy demand of the facility 12 (the ship's propulsion engine is stopped or operating at low load, gas is used mainly to meet electricity and heating needs) Be done).
2. Normal consumption: Natural boil-off does not cover the ship's energy needs.
3. No consumption (all gas consuming elements mounted on the facility 12 except the gas compressor are stopped).
4. filling.

This is a continuous method in which the buffer tanks 18 and 40 are alternately filled and emptied. Only the filling and draining of the tank 18 will be described intensively, but the process for the tank 40 is symmetrical thereto.

1. Minimum consumption (see Figure 8)

In the operation phase shown 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 to 3 MW).

The evaporation of LNG 16aa in the tank 16 increases the pressure of the BOG 16ab in the tank 16. The BOG 16ab is sucked by the compressor 20, heated by the exchanger 28, and sent to the facility 12. This allows the pressure in tank 16 to be maintained below an acceptable threshold.

The following operations are possible to adjust the pressure in the tank 16.
Adjusting the flow rate of the BOG sent to the compressor 20 (if the flow rate is higher than the natural boil-off speed, the pressure in the tank 16 drops; if the flow rate is lower than the natural boil-off speed, the pressure in the tank rises).
Re-inject some of the compressed gas (exiting the compressor 20) into the main tank 16 (e.g. due to the specifications of the compressor 20 the input flow rate of the compressor is reduced below a certain value (here greater than the natural boil-off speed)) If this is not possible, some of the compressed gas is reinjected into the tank 16 via the pipe 38.

Therefore, the device 10 supplies the required amount to the facility 12 with the gas coming from the tank 16 and maintains the pressure inside the tank at the required level (eg, -100 mbarg to 700 mbarg).

2. Normal consumption

In the second phase of operation, consumption is normal.

The natural boil-off in tank 16 is insufficient to meet the energy demand of facility 12. Forced boil-off is required to meet the ship's energy needs. This phase includes the following two steps.
-Preparation for forced boil-off: Fill buffer tank 18 with liquefied natural gas from tank 16.
-Forced evaporation: the liquid from the buffer tank 18 is sent to the exchanger and then to the installation (while filling the other buffer tank 40 with LNG).

-Preparation for forced evaporation (Fig. 9)

The first step is to reduce the pressure in the buffer tank 18 and/or increase the pressure in the tank 16 to cause a pressure difference of, for example, -500 mbar between the main tank 16 and the buffer tank 18. Consists of. The pressure in tank 16 may be increased as described in the first phase. The pressure in the buffer tank 18 can be lowered by sucking the natural gas in the buffer tank by the compressor 20. Due to this pressure difference (-500 mbar), LNG can be sucked from the tank 16 from a height of approximately 10 m.

When the pressure rises in the tank 16, the BOG from the tank 16 forces LNG to flow out of the tank and flow through the pipe 22 to the buffer tank 18. When the pressure drops in the buffer tank 18, the LNG contained in the tank 16 is sucked into the tank 18. The pressure difference contributes to the partial boil-off of LNG in the tank 18. The boil-off gas is sucked by the compressor 20 so that the pressure difference between the tanks 16, 18 can be maintained. The tank 18 is filled with liquefied natural gas, for example up to 90% of its capacity. These operations may be combined with the first operation phase to adjust the pressure in the tank 16.

-Forced evaporation (Fig. 10)

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

The tank 18 is filled with liquid and the pipe 22 and valve 23b used to draw natural gas from the tank are closed. The compressed gas exiting the compressor 20 is sent to the tank 18 (a part thereof if necessary) and is pressurized. This may force LNG from the tank 18 to flow through the exchanger 34 and the facility 12.

While LNG is being supplied from tank 18 to facility 12, tank 40 is filled with LNG from tank 16 (thus, only valves 23d and 23e are closed and valves 23b and 23f are open). Advantageously, the device 110 is designed such that the compressor 20 can be used to fill the tank 40 at a faster rate than LNG is discharged from the tank 18.

The flow rate and pressure of LNG at the outlet of the buffer tank 18 are adjusted by the valve 33b. The tank 18 is used until its LNG level is sufficiently low (eg 5% of its capacity). From this point, the tank 40 can supply LNG to the facility 12 more. Then, as described in the first step, the tank 16 is filled with LNG.

Therefore, in this phase, the tanks 18, 40 are alternately filled with LNG and compressed using the compressor 20 to supply LNG to the facility 12.

These operations may be combined with the first operation phase to adjust the pressure in the main tank 16.

3. No consumption (see Figure 11)

This operating phase is activated in an emergency. The facility 12 is stopped. That is, there is no consumption of fuel gas. The exchanger 28 and the compressor 20 are operated by an emergency generator.

In this phase, it is assumed that the tanks 16 and 18 contain LNG. A compressor 20 is used to deliver compressed gas to the tank 18 to raise the pressure within the tank. As a result, the LNG is forcibly discharged from the tank and directed toward the manifold 52, so that the LNG is sprayed onto the BOG in the tank 16. As a result, the BOG in the tank 16 can be condensed, so that the pressure reduction and the pressure maintenance in the main tank 16 are realized.

Therefore, the pressure in the tank 16 is adjusted by the flow rate of LNG coming from the buffer tank 18 and sprayed by the manifold 52.

When the tank 18 is empty, this operation is repeated using the tank 40, during which the tank 18 is refilled.

This operating phase may be combined with the first or second phase to reduce the pressure in the main tank 16.

4. Filling (see Figure 12)

The valve 23d is opened. LNG from the filling station is sent to tank 16. BOG boiled off during filling is discharged by opening valves 31a and 31c as well, forming a free flow of BOG to the station.

FIG. 13 shows a modified embodiment of the device 210 according to the invention. This variant embodiment differs from the device 110 in particular in that it includes a pump 36.

The features described above with reference to apparatus 110 apply to apparatus 2110 unless they are consistent with the description below.

The pump 36 is arranged in the pipe 54. The upstream end of the pipe 54 connects to the outlets 18c, 40c of the tanks 18, 40 immediately downstream of their valves. The downstream end of the pipe 54 is connected to the pipe 32 immediately upstream of the valve 33b. The pipe 54 includes a valve 56 and extends parallel to a portion of the pipe 32. The pipe 32 includes a further valve 58. This configuration provides the option of using or not using the pump 36 to drain the LNG contained in the tanks 18, 40 and send it to the spray manifold 525 and/or the facility 12. provide.

Therefore, the device operates in a hybrid manner with respect to the device 10, 110.

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

The prior art includes, inter alia, the documents WO-A1-2012/089891, DE-A1-102013 011 212, FR-A1-3 028 305 , and WO-A1-2015/183966.

In order to more easily transport a gas such as natural gas over a long distance, the gas is liquefied by cooling to a cryogenic temperature at atmospheric pressure, for example, to -163° C. (which is liquefied natural gas (LNG). To)). After that, the liquefied gas is carried into the special ship.

For example, a methane tanker type ship for transporting liquefied gas is provided with energy production equipment to meet the energy demands of the operation of the ship, especially the propulsion of the ship and/or the production of electricity for onboard equipment. There is.

This type of installation typically includes a thermomechanical that consumes gas from an evaporator powered by a cargo of liquefied gas that is transported to the tank or tanks of the vessel.

Document FR-A-2 837 783 defines power supply to this type of evaporator and/or other systems necessary for propulsion with a pump submerged in the bottom of the tank of a ship.

Pumps arranged in this way have drawbacks. According to the IACS (International Association of Classification Societys) code, pumps must be inspected on a regular basis. Inspection of the pump requires the main tank to be opened, so the ship may be stationary and may damage the tank.

The solution to this problem is to provide an opening in the bottom of the tank and to discharge the liquefied gas from the main tank through this opening. However, the IGF and IGC Codes (International Regulations on the Structure and Equipment of Ships for Bulk Transport of Liquefied Gases) prohibit such openings in large capacity tanks, such as in the case of the main tank of a ship.

The present invention proposes a simple, effective and economical improvement over the current state of the art.

The present invention is
In particular, a device for supplying a fuel fluid to a power generation facility mounted on a ship,
-Main liquefied fuel gas tank,
-At least one first liquefied gas buffer tank,
A first pipe for transferring a fluid or a liquefied gas from the first buffer tank to the installation, the first end of the first pipe opening into the first buffer tank, the first pipe A second end of the first pipe connecting to the facility for supplying fuel fluid to the facility;
A second pipe for transferring liquefied gas from the main tank to the first buffer tank, the first end intended to be immersed in the liquefied gas housed in the main tank; A second pipe having a second end opening into the first buffer tank to supply liquefied gas to the first buffer tank;
-Means for lowering the pressure in the first buffer tank with respect to the main tank, sucking the fluid in the first buffer tank, and in the first buffer tank, Means adapted to transfer a liquefied gas from the main tank through the second pipe to supply the first buffer tank by applying a low operating pressure;
In a device including
The pressure reducing means includes at least one compressor,
A device is proposed, characterized in that the operating pressure is preferably below atmospheric pressure.

The device according to the invention thus addresses the problems of the prior art. Here, the pump immersed in the main tank is not essential for sending the liquefied gas from the main tank to the buffer tank. The reduced pressure in the buffer tank, that is, the pressure difference between the buffer tank and the main tank may cause the buffer tank to supply the liquefied gas contained in the main tank. Therefore, the liquefied gas flows from the main tank to the buffer tank in the second pipe. The BOG housed in the main tank can be conventionally used to supply the equipment of a ship. Here, the device makes it possible to add to this BOG source an additional fluid which is available in the gas or liquid state in the buffer tank and which can be sent to the installation by means of the first pipe.

The first buffer tank may have a pressure reduced to a pressure lower than atmospheric pressure (eg, −600 mbar or more and −100 mbarg or less, or −600 mbarg or more and −200 mbarg or less). Even if the buffer tank has a pressure close to atmospheric pressure, for example, -100 mbar or more and 100 mbarg or less, or -100 mbarg or more and 250 mbarg or less, or -s 100 mbarg or more and 400 mbarg or less, the liquefied gas is transferred from the main tank to the buffer tank. The compressor can cause this kind of pressure drop.

This allows, for example, an immediate supply of gas to equipment including a motor, while the prior art requires waiting until the pressure in the main tank rises to a level sufficient to supply the motor. There is. Furthermore, it should be noted that in this case the pressure must be at a level compatible with the motor, for example above 6 barg, and that the tank and especially the tank type can be selected depending on its pressure resistance.

The device according to the invention has one or more of the following features, either individually or in combination with one another.
-The main tank is a membrane type. That is, its wall, in particular its inner wall, comprises at least one metal layer forming a sealing membrane and at least one heat insulating layer.
The main tank is configured to withstand a pressure of 3000 mbarg or less, preferably 750 mbarg or less.
The main tank is of the membraneless type.
The main tank is configured to withstand a pressure of 3000 mbarg or higher, preferably 6000 mbarg or higher.
The pressure reducing means has an outlet intended to connect to the installation.
-The pressure reducing means comprises at least one compressor.
A pump is arranged to connect to the first pipe and to suck liquefied gas from the first buffer tank.
-The compressor is connected to a third pipe so as to reduce the pressure in the first buffer tank, the first end of the third pipe opening into the first buffer tank, The second end is connected to the inlet of the compressor, and the third pipe is configured to suck the boil-off gas in the first buffer tank and supply the boil-off gas to the compressor.
-The compressor has an outlet connecting to the facility for supplying fuel gas to the facility.
The second end of the third pipe is connected to the compressor by a first circuit of a heat exchanger.
The device comprises a fourth pipe for transferring gas from the main tank to the compressor.
-The fourth pipe has a first end opening to the main tank and a second end connecting to the compressor.
The second end of the fourth pipe is connected with the second pipe to the inlet of the first circuit of the heat exchanger, the outlet of the heat exchanger being connected to the compressor.
-The first end of the second pipe does not have a pump.
-The first pipe comprises at least a pump, and/or a pressure reducing valve, and/or a heat exchanger. The heat exchanger may be configured to vaporize the liquefied gas flowing through the first pipe to supply the fuel gas to the facility.
-The pump is arranged to be controlled according to the fuel gas demand of the installation.
-The device comprises a fifth pipe for returning fluid from the decompression means to the main tank, the first end of the fifth pipe being connected to the outlet of the decompression means, Two ends open to the main tank.
-The device comprises a second liquefied gas buffer tank.
-The second buffer tank is
A first pipe that is the first pipe and has a third end that opens into the second buffer tank;
A second pipe having the third end opening to the second buffer tank, which is the second pipe;
Connect to.
-The second buffer tank is connected to the third pipe, the third pipe having a third end opening into the second buffer tank.
-The device comprises a fifth pipe for supplying gas to the first buffer tank and the second buffer tank, the first end of the fifth pipe being connected to the outlet of the pressure reducing means, The second end of the fifth pipe opens into the first buffer tank, the third end of the fifth pipe opens into the second buffer tank, and the fifth pipe opens into the first buffer tank. And/or is configured to supply compressed gas to the buffer tank.
-The first pipe is connected by a sixth pipe to a manifold for spraying liquefied gas into the main tank, and the manifold sprays liquefied gas in a droplet state onto boil-off gas in the main tank. It is configured to condense at least a portion of the boil-off gas.
-Each tank is provided with a pressure sensor and/or a level sensor.
-The or each buffer tank is arranged below the upper end of the main tank.
-The or each buffer tank is arranged outside the main tank.
-The or each buffer tank may have expansion and/or separation functions. At least a part of the liquefied gas supplied to the buffer tank may be partially evaporated and phase-separated in the tank. Less than half, or less than 10% of the aspirated liquefied gas can thus be evaporated. The gas outlets in liquid and gaseous form can be connected to the installation without passing through the main tank or again. Since a small part (1% to 10%) of the taken out LNG evaporates in the upstream of the compressor, a compressor having a small flow rate can be used. In fact (for gas LNG demand with energy production facilities) less suction is needed than if only gas was sucked in (gas volume is approximately 600 times liquid volume).
-The gas comprises at least one pure substance or gas.
For example,
-The first pipe transfers (in liquid form) at least part of the pure gas and optionally other gases from the buffer tank to the facility, and/or
-The compressor draws at least a portion of the pure gas, optionally mixed with other gases, and/or
-The compressor supplies the facility with pure gas (optionally mixed with other gases).

As used herein, “pure” refers to a single chemical species or substance with respect to a mixture of substances or species. The pure gas is, for example, a light gas or a heavy gas.

In the present application, heavy gas and light gas respectively mean a heavy gas, ie a gas with a high molar volume, and a light gas, ie a gas with a low molar mass. In the liquefied gas, the light gas is generally methane. In the liquefied gas, the light fraction may contain a small amount of nitrogen. Smaller heavy fractions include, for example, in the case of liquefied gases, propane, butane and ethane (thus it evaporates at higher temperatures or lower pressures). In the liquefied gas, the heavy gas corresponds to 5.2% to 49.8% of the total mass of the liquefied gas. The heavy gas has, for example, a molar mass that is 25% to 500% greater than the molar mass of the light gas.

The invention further relates to a ship, in particular for transporting liquefied gas, comprising at least one device as described above. The invention has particular application to ships propelled by liquefied fuel gas, such as LNG. This is the case, for example , in the case of ships for transporting liquefied gas , if the propulsion tank is also considered to have a transport function).

The present invention further comprises
In particular, a method for supplying fuel to an energy production facility mounted on a ship by the above-mentioned device,
-A step A of transferring liquefied gas from the main tank to the first buffer tank by lowering the pressure in the first buffer tank with respect to the main tank, and filling the first buffer tank;
And a method comprising:

The method according to the invention may comprise or have one or more of the following steps, or one or more of the following features, either separately from one another or in combination with one another.
The method comprises a step B1 of sucking the gas in the first buffer tank by the compressor to supply it to the installation.
-In step B1, the equipment is supplied by the compressor by taking in gas in the main tank and the first buffer tank.
-The method comprises a step B2 of supplying the equipment by supplying gas to the first and/or second buffer tanks by the compressor to force liquefied gas to flow through the first pipe. ..
-In step B1 or B2, the liquefied gas is transferred from the main tank to the second buffer tank by lowering the pressure in the second buffer tank with respect to the main tank by the compressor, and the second buffer Supply liquefied gas to the tank.
-In step A, the pressure in the main tank is controlled by adjusting the flow rate of the gas flowing through the fourth pipe and/or the fifth pipe.
-In or after step A, the pump of the first pipe is supplied with liquefied gas from the first buffer tank.
The method comprises a step B3 of supplying the equipment via the first pipe by operating the pump.
-In step A, the reduced pressure is continuously maintained for a predetermined time.
-The hydrostatic pressure generated by the substantially linear vertical height of the second pipe, which is the pressure difference between the buffer tank and the main tank, and where necessary the head loss in the second pipe is subtracted. The pressure is reduced by applying a larger pressure difference.
-The pump is controlled according to the fuel gas demand of the installation.
-At least some valves provided in one or more of the pipes are controlled according to the fuel gas demand of the installation.
-As soon as the liquefied gas level in the buffer tank falls below a predetermined threshold level, the pressure difference between the buffer tank and the main tank is immediately increased to increase the liquefied gas flow rate supplied from the buffer tank. Let
The pressure difference between one of the buffer tanks and the main tank is adjusted according to the rate at which the other buffer tank is filled with liquefied gas from the main tank.
-The liquefied gas stored in the buffer tank is sent to the spray manifold by the first and sixth pipes.

The invention will be better understood and further details, features and advantages of the invention will emerge more clearly on reading the following description, given by way of non-limiting example, with reference to the accompanying drawings, in which:

1 is a schematic view of an apparatus according to a first embodiment of the present invention, which is installed in a ship. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 2 is a schematic diagram corresponding to FIG. 1 and showing the steps of the method according to the invention. FIG. 3 is a schematic view of an apparatus according to a second embodiment of the present invention, which is installed in a ship. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 8 is a schematic diagram corresponding to FIG. 7, showing the steps of the method according to the invention. FIG. 6 is a schematic view of an apparatus according to a third embodiment of the present invention, which is mounted on a ship.

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

FIG. 1 shows a device 10 according to a first embodiment of the invention. The device 10 is assumed to be capable of supplying fuel gas to a ship such as a ship that transports liquefied gas. Accordingly, the apparatus 10 may be used to supply fuel gas to an energy production facility 12 on board a vessel 14.

The vessel 14 includes a single tank 16 or a plurality of similar tanks 16 for storing liquefied gas. The gas is, for example, methane or a gas mixture containing methane. The tank 16 or each tank 16 may contain a gas in a liquefied state at a predetermined pressure and a predetermined temperature, for example, atmospheric pressure and a temperature of about −163° C. The tank(s) 16 of the vessel may be connected to the installation 12 by means of the device 10 according to the invention. Therefore, the number of tanks is not limited to the present invention and is, for example, 1 or more and 6 or less. Each tank 16 may have a capacity of 1000 (or 100) ^{m 3} to 50000 m ^3.

Hereinafter, the expression "tank 16" should be construed as meaning "tank 16 or each tank 16".

The tank 16 contains the liquefied gas 16aa and the gas 16ab generated from the boil-off (evaporation) of the liquefied gas 16aa in the tank 16, especially natural boil-off. The liquefied gas 16aa is naturally stored at the bottom of the tank 16, whereas the boil-off gas 16ab is located above the level (height) of the liquefied gas in the tank, which is schematically represented by the letter N.

In the following, "LNG" means liquefied gas, that is, liquid state gas, "BOG" means boil-off gas, "NBOG" means natural boil-off gas, and "FBOG" means forced boil-off gas. And These abbreviations correspond to the first letter of the relevant English word and are known to those skilled in the art.

In the embodiment shown in FIG. 1, the end 22a of the pipe 22 is immersed in the LNG 16aa in the tank 16. Preferably, there is no pump at this end so that no maintenance is required. The end is preferably located at the bottom of the tank, which ensures that the pipe is only supplied with liquid LNG, even if the tank is almost empty.

In the present application, the "bottom" of a tank means a position that is less than 1 meter from the bottom wall of the tank. This bottom wall is the wall of the tank that is closest to the center of the earth during operation.

The pipe 22 includes a branch connection and has two ends located outside the tank 16. One end 22d forms a port for filling the tank 16 with LNG, which is accessible to the user, especially when LNG is loaded into the tank of the vessel.

The other end 22b of the pipe is connected to the buffer tank 18, which is also located outside the tank 16. The valves 23d and 23b are associated with the ends 22d and 22b, respectively. The valve 23d can block the flow of fluid in the pipe 22 and thus the supply of LNG to the tank 16. The valve 23d may form a check valve. The valve 23b can block the supply of fluid to the buffer tank 18, especially during refueling of the main tank 16.

A manifold 52 for spraying LNG droplets is located above the level N at the top of the tank 16. Therefore, the manifold 52 is configured to spray LNG droplets onto the BOG in the tank. As a result, the BOG in the tank 16 can be forcibly recondensed.

The tank 16 further includes a BOG inlet 16a and a BOG outlet 16b. The outlet 16b is connected to the one end 30a of the fourth pipe 30. The pipe 30 also includes a branch connection that defines two ends located outside the tank 16. One end 30c forms a port for discharging BOG from the tank 16. The end 30c is accessible to the user, especially when loading LNG into the tank 16 of a ship.

The other end 30b of the pipe 30 is connected to the inlet 28aa of the first circuit 28a of the heat exchanger 28. The outlet 28ab of the first circuit 28a of the heat exchanger 28 is connected to the inlet 20a of the compressor 20. The first circuit 28a is a cold circuit and it is intended that the fluid flowing through the circuit 28a is heated by the second circuit 28b of the exchanger 28, ie the fluid flowing through the hot circuit.

Valves 31a, 31c are associated with each end 30a, 30c. The valve 31a can block the flow of fluid through the pipe 30, and thus the discharge of the BOG from the tank 16. The valve 31a may form a check valve. The valve 31c can block exhaust to the end 30c of the BOG and the corresponding port.

The inlet 16a of the tank 16 is connected to one end 38b of the pipe 38. The other end 38a of the pipe 38 connects to the outlet 20b of the compressor 20. A valve 39 is associated with the pipe 38 and blocks the passage of fluid from the outlet of the compressor 20 to the tank 16. The outlet 20b of the compressor 20 is further connected to the facility 12 by a valve 41.

The buffer tank 18 includes 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 and the buffer tank 18 is intended to be supplied with LNG coming directly from the tank 16.

The outlet 18b is an outlet for gas which is especially BOG, and the outlet 18c is an outlet for LNG. The outlet 18b is connected to one end 26a of the pipe 26. The opposite ends 26b of the pipes 26 are connected to the inlet 20a of the compressor 20. In the illustrated example, the BOG exiting the buffer tank 18 is preheated by the exchanger 28 before being supplied to the compressor 20. For this purpose, the pipe 26 is connected to the pipe 30 upstream of the exchanger 28 and more specifically upstream of the first circuit 28a. Thereby, BOG coming from both the tank 16 and the buffer tank 18 can be supplied to the first circuit 28 a and heated before being supplied to the compressor 20.

The pipe 26 comprises a valve 27 capable of blocking the passage of fluid in the pipe 26, in particular the discharge of BOG from the buffer tank 18 to the exchanger 28.

The outlet 18c is connected to one end 32a of the pipe 32. The pipe 32 is connected to the facility 12 at the outlet 20b of the compressor 20. This pipe 32 includes or is connected to a pump 36 and is connected to a heat exchanger 34. The pipe 32 further includes two valves 33a, 33b including, for example, a pressure reducing valve 33b. In the illustrated example, the pump 36, the valve 33b, the exchanger 34, and the valve 33a are arranged from the upstream side to the downstream side, that is, from the tank 18 toward the outlet 20b of the compressor 20.

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

In the illustrated example, LNG discharged from the buffer tank 18 by the pump 36 is evaporated in the exchanger 34 before being supplied to the facility 12. For this purpose, the pipe 32 is connected to the inlet 34aa of the first circuit 34a of the heat exchanger 34. The outlet 34ab of the heat exchanger 34 is connected to the valve 33a. The first circuit 34a is a cold circuit and it is intended that the fluid flowing through the circuit 34a is heated by the fluid flowing through the second circuit of the exchanger 34, the hot circuit 34b.

If the valve 33b is a pressure reducing valve and all LNG can be evaporated as FBOG, the FBOG may be heated by the exchanger 34 before being supplied to the facility 12. Therefore, the valve 33b is advantageously configured to match the pressure at the outlet of the FBOG with the pressure at which the fuel gas is used in the facility 12.

A spray manifold 52 is connected to the pipe 32 by a pipe 50 provided with a valve 51. Its upstream end is connected to the pipe 32 between the pump 36 and the valve 33b, ie just downstream of the pump 36. Also, its downstream end is connected to the manifold 52. Therefore, as described above, it is clear that the LNG housed in the buffer tank 18 can be supplied to the spray manifold 52.

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 pressure at which LNG is stored in the tank 16. Therefore, when LNG is supplied to the buffer tank 18, the LNG is partially evaporated, FBOG is generated in the buffer tank 18 reflecting this, and the remaining LNG in the buffer tank 18 is cooled. This is called "subcooled liquefied gas". The buffer tank 18 stores a liquid-shaped gas having a predetermined pressure and a predetermined temperature.

Therefore, the buffer tank 18 contains the subcooled liquefied gas 18aa and the boil-off of the liquefied gas 16aa from the tank 16, here the gas 18ab generated by the forced boil-off. The subcooled liquefied gases (LNGs) 18aa are naturally stored at the bottom of the buffer tank 18, whereas the boil-off gas (ie FBOG) 18ab is the liquefied gas in the buffer tank 18 represented schematically by the letter L. Located above the level.

Here, the compressor 20 is used to apply an operating pressure in the buffer tank 18. Therefore, it is configured to reduce the pressure in the buffer tank 18 against the tank 16. The pressure differential between them may be sufficient to force LNG from tank 16 into buffer tank 18. Therefore, in the latter case, it is clear that the immersion pump at the end 22a of the pipe 22 is unnecessary. The conditions imposed on the buffer tank 18 by the compressor 20 are determined to produce LNGs within the buffer tank 18.

Alternatively or additionally, pump 36 may be configured to help reduce the pressure in buffer tank 18 relative to main tank 16.

If the amount of LNGs in buffer tank 18 becomes too high to reach a threshold level, LNGs may be transferred from the LNGs outlet of buffer tank 18 to spray manifold 52 in facility 12 and/or tank 16.

LNGs provide cooling power. When the cooling power is unnecessary, for example, the cooling power can be stored in the buffer tank 18 in a phase in which the amount of NBOG generated is insufficient to satisfy the demand amount.

In the illustrated example, the pressure drop in tank 18 may allow LNG to flow through pipe 22. Pipe 22 includes a vertical portion that forms a dip tube that is dipped in LNG in tank 16. Its upper end is connected to the rest of the pipe 22 by a tee. The pressure difference between the two tanks 16, 18 should preferably be greater than the hydrostatic pressure created by the height of the pipe 22 minus the head loss in the pipe 22. More precisely, this is the height of the vertical portion of the pipe 22 up to the tee above the bottom of the tank (because the LNG must be able to be raised to this height when the tank 16 is empty). From). Alternatively, if the tank 18 (more precisely the outlet 22b) is below this height and the pipe 22 is primed (when the tank 16 is almost full, for example by a smaller pressure difference), the pressure difference will be smaller. Good.

The pressure difference can be adjusted by the following method.
-Control the pump 36 according to the gas demand of the facility 12 (the gas demand is determined, for example, by the difference between the set value of the facility 12 and the flow rate of the gas measured between the outlet 32b and the facility 12). Be done).
The tank 18 has a level sensor. When the level in the tank 18 falls below the lower threshold, the pressure difference is immediately increased to increase the flow rate to the tank 18 (also the upper threshold level is provided to reduce the pressure difference immediately upon reaching that level). Or it may be offset).

The fuel gas supply device has two main functions described below.
-The fuel gas is supplied from the main tank 16 to the equipment of the ship at a desired flow rate (for example 50 kg/h to 2000 kg/h), a predetermined pressure (for example 6 bar to 300 bar) and a predetermined temperature (for example 20°C). The fuel gas may have a gas form (vapor) or a liquid form.
-Adjust the pressure in the main tank 16 within an acceptable range (e.g. -100 mbarg to +700 mbarg, or -700 mbarg to 6000 mbarg).

The described apparatus 10 is, for example, designed to contain a cryogenic liquid at atmospheric pressure (eg, a capacity of 1000 m ³ (or 100 m ³ ) to 10000 m ³ and a licensed pressure of −100 mbar to +700 mbarg or −700 mbarg to 6000 mbarg). And a buffer tank 18 intended to contain a cryogenic liquid (for example having a capacity of 1 m ^{3 to} 20 m ³ and an allowable pressure of −500 mbar to 6000 mbar). A compressor 20 and/or pump 36 allows a pressure differential between the main tank 16 and the buffer tank 18 (e.g. +500 mbar). The liquid in the buffer tank 18 is compressed by the pump 36 and sent to the facility 12 via the evaporation valve 33b. The level of liquid in the buffer tank 18 is controlled using suitable equipment, for example 10% to 90% of the capacity of the buffer tank. In this way, the pump 36 is always supplied with 100% liquefied gas (a mixture of natural gas in the gas and liquid states can damage the pump). The method of controlling the device and the appropriate equipment are designed such that the pressure in the main tank 16 is maintained at the required level (eg, -100 mbarg to 700 mbarg). Therefore, advantageously, each tank of the device 10 is provided with a pressure sensor and/or a level sensor.

2 to 6 show the phases of operation of the device of FIG. These operating phases may correspond to the operating phases of a ship equipped with the device.

The supply method will be described in the following three phases.
1. Minimum Consumption: Natural boil-off covers the energy needs of the facility (the ship's propulsion engine is off or operating at low load, gas is used primarily to meet electricity and heating needs). ).
2. Normal consumption: Natural boil-off does not cover the ship's energy needs.
3. No consumption : (All gas consumption elements mounted on the facility 12 except the gas compressor are stopped).
4. filling.

1. Minimum consumption (see Figure 2)

In the operation phase shown in FIG. 2, the main engine of the ship is stopped and the power consumption is less than the maximum capacity of the compressor 20 (<2 to 3 MW).

The pressure of the BOG 16ab in the tank 16 rises due to the evaporation of the LNG 16aa in the tank 16. The BOG 16ab is sucked by the compressor 20, heated by the exchanger 28, and sent to the facility 12. This allows the pressure in tank 16 to be maintained below an acceptable threshold.

The following operations are possible to adjust the pressure in the tank 16.
-Adjust the flow rate of BOG sent to the compressor 20. For example, when the flow velocity is higher than the natural boil-off velocity, the pressure in the tank 16 drops. When the flow velocity is lower than the natural boil-off velocity, the pressure in the tank rises.
Re-inject some of the compressed gas (exiting the compressor 20) into the main tank 16 (e.g. due to the specifications of the compressor 20 the input flow rate of the compressor is reduced below a certain value (here greater than the natural boil-off speed)) If this is not possible, some of the compressed gas is reinjected into the tank 16 via the pipe 38 and the pressure in the tank 16 is adjusted.

Thus, the device 10 supplies the required amount to the facility 12 with the gas coming from the tank 16 and maintains the pressure inside the tank at the required level (e.g. -100 mbarg to 700 mbarg).

2. Normal consumption

In the second phase of operation, consumption is normal.

The natural boil-off in tank 16 is insufficient to meet the energy demand of facility 12. Forced boil-off is required to meet the ship's energy needs. This phase includes the following two steps.
-Preparation for forced boil-off: Fill the buffer tank 18 and pump 36 with liquefied natural gas.
-Forced evaporation: the liquid from the buffer tank 18 is forcibly evaporated and sent to the facility.

-Preparation for forced evaporation (Fig. 3)

The first step is to reduce the pressure in the buffer tank 18 and/or increase the pressure in the tank 16 to create a pressure difference between the main tank 16 and the buffer tank 18 of, for example, -500 mbar. Become. As mentioned above, the pressure in tank 16 may be increased by reinjecting compressed BOG into it. The pressure in the buffer tank 18 can be lowered by sucking the natural gas in the buffer tank by the compressor 20. Due to this pressure difference, the LNG accommodated in the tank 16 can be sucked from a height of 10 m.

When the pressure rises in the tank 16, the BOG accommodated in the tank 16 tries to push the LNG out of the tank 16, so that the LNG is forced to flow through the pipe 22 to the buffer tank 18. When the pressure in the buffer tank 18 decreases, LNG is sucked from the tank 16 into the buffer tank 18. The pressure difference contributes to partial (flash) evaporation and formation of BOG in the buffer tank 18. The BOG is sucked by the compressor 20 and the pressure difference between the tanks 16 and 18 is maintained.

The second step is to fill pump 36 with liquefied natural gas. When the buffer tank 18 is filled to the required level with liquefied natural gas, for example 90% of its capacity, LNGs are fed to the pump 36 by gravity. Pump 36 must be completely filled with liquid. This is because otherwise bubbles could be generated which could damage the pump. The LNGs flow in the pipe 32 to the pump 36 and pass therethrough. Leave the pump closed.

These operations may be combined with the first operation phase to adjust the pressure in the main tank 16.

-Forced evaporation (Fig. 4)

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

LNG from the buffer tank 18 is sent to the facility 12 via the exchanger 34. The flow rate of LNGs sent to the facility 12 is adjusted by the pump 36. The facility 12 prioritizes receiving gas from the compressor 20 (which manages the pressure in the tanks 16, 18) and obtains make-up gas by the pump 36. The make-up gas is used to flow LNG through valve 33b to vaporize, preferably to completely vaporize LNG prior to heating in exchanger 34. As described above, LNG is supplied to the buffer tank 18 by lowering the pressure in the tank 18 with respect to the tank 16. The outflow of LNG from the buffer tank 18 is adjusted by the pump 36. The level of LNG in the buffer tank 18 is adjusted to be maintained at a required level, for example 10% to 90% of its capacity.

These operations may be combined with the first operation phase to adjust the pressure in the main tank 16.

3. No consumption (see Figure 5)

This operating phase is activated in an emergency. The facility 12 is stopped. That is, there is no consumption of fuel gas. The exchanger 28, the compressor 20, and the pump 36 are operated by an emergency generator.

In this phase, it is assumed that the tanks 16 and 18 contain LNG. The pump 36 allows LNG to flow from the buffer tank 18 to the manifold 52. Due to the pressure difference between the tanks 16 and 18, the LNG continues to flow from the tank 16 to the buffer tank 18 and boil off in the latter. This means that the LNG formed in the buffer tank 18 is subcooled compared to the LNG housed in the tank 16. The subcool liquefied gas from the buffer tank 18 is supplied to the manifold 52, and the manifold 52 sprays droplets of the gas onto the BOG in the tank 16. As a result, the BOG in the tank 16 can be condensed, so that the pressure reduction and the pressure maintenance in the main tank 16 are realized.

Therefore, the pressure in the tank 16 is regulated by the flow of LNG coming from the buffer tank 18 and sprayed by the manifold 52. This operating phase may be combined with the first or second phase to reduce the pressure in the main tank 16.

4. Filling (see Figure 6)

The valve 23d is opened. LNG from the filling station is sent to tank 16. BOG boiled off during filling is drained by opening valves 31a and 31c, forming a free flow of BOG to the station.

FIG. 7 shows a device 110 according to a modified embodiment of the invention. This variant embodiment differs from the device 10 in particular in that it comprises two buffer tanks 18 and 40.

The features described above with reference to device 10 apply to device 110 unless they are inconsistent with the description below.

The pipe 22 is connected to each of the tanks 18 and 40, and has an end 22b connected to the LNG inlet 18a of the tank 18 and an end 22c connected to the LNG inlet 40a of the tank 40. In addition to the valves 23b and 23d of the pipe 22, valves 23e and 23f are associated with the ends 23b and 23d, respectively.

Here, each buffer tank 18, 40 includes four ports, namely two inlets 18a, 40a, 18d, 40d and two outlets 18b, 40b, 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 is intended to be supplied with LNG coming directly from the tank 16.

The outlets 18b, 40b are outlets for gas, in particular BOG, and the outlets 18c, 40c are LNG outlets. The outlets 18b and 40b are connected to the respective ends 26a and 26c of the pipe 26. The opposite end 26b of the pipe 26 is connected to the inlet 20a of the compressor 20 or, as mentioned above, to the inlet 28aa of the circuit 28a of the exchanger 28.

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

Another pipe 42 connects the outlet 20b of the compressor 20 to the tank inlets 18d, 40d. The inlets 18d, 40d are the inlets for the compressed gas or BOG, as the compressed BOG may be supplied to the tanks 18, 40, as described in more detail below. The pipe 42 includes a valve 43 that blocks the passage of fluid from the outlet of the compressor 20 to the tanks 18, 40. Further, each inlet 18d, 40d is associated with a valve that allows the tanks to be isolated from each other.

The outlets 18c, 40c of the tanks 18, 40 are connected to the ends 32a, 32c of the pipe 32 connected to the outlet 20b of the compressor 20. This pipe 32 includes or is connected to a heat exchanger 34. The pipe further comprises two valves 33a, 33b, one of which is, for example, a pressure reducing valve 33b. In the illustrated example, the valve 33b, the exchanger 34, and the valve 33a are arranged in the direction from upstream to downstream, that is, from the tanks 18, 40 toward the outlet 20b of the compressor 20. Valves are further associated with each outlet 18c, 40c.

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

In the illustrated example, the LNG discharged from the buffer tank 18 is preheated by the exchanger 34 before being supplied to the facility 12. For this purpose, the pipe 32 is connected to the inlet 34aa of the first circuit 34a of the heat exchanger 34 and the outlet 34ab of the first circuit 34a is connected to the valve 33a. The first circuit 34a is a low temperature circuit, and it is intended that the fluid flowing through the circuit 34a is heated by the second circuit 34b of the exchanger 34, that is, the fluid flowing through the high temperature circuit.

If the valve 33b is a pressure reducing valve and it is possible to vaporize all LNG to form the FBOG, the FBOG may be heated by an exchanger before being supplied to the facility 12. Therefore, the valve 33b is advantageously configured to match the pressure at the outlet of the FBOG with the pressure at which the fuel gas is used in the facility.

The pipe 50 connects the spray manifold 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 manifold 52. Therefore, as described above, it is clear that the LNG housed in the buffer tanks 18, 40 can be supplied to the spray manifold 52.

In the illustrated example, the pressure drop in tank 18 must allow LNG to flow through pipe 22. The pipe 22 has a vertical section that forms a dip tube that is dipped in the LNG in the tank 16. Its upper end is connected to the rest of the pipe 22 by an elbow. The pressure difference between the two tanks 16, 18 is preferably the height of the pipe 22 less the head loss in the pipe 22 , more precisely the height of the vertical portion of the pipe 22 from the bottom of the tank to the elbow. Must be greater than the hydrostatic pressure generated by. This is because the LNG must be able to be raised to this height when the tank 16 is empty. Alternatively, if the tank 18 (more precisely the outlet 22b) is below this height and the pipe 22 is primed (when the tank 16 is almost full, for example by a smaller pressure difference), the pressure difference will be smaller. Good.

The pressure difference can be adjusted by the following method.
Controlling the valves corresponding to the outlets 18c, 40c of the tanks 18, 40 according to the gas demand of the facility 12.
-Adjust the pressure difference so that these buffer tanks fill fast enough . Therefore, the difference also depends on the gas demand of the facility 12.

Each tank 18, 40 functions similarly to tank 18 of device 10. Furthermore, the tanks 18, 40 have a supplementary function by being connected to the outlet 20b of the compressor 20. The compressed BOG leaving the compressor 20 and supplied to the tanks 18, 40 can pressurize these tanks 18, 40 and force the LNG 18aa, 40aa through the outlets 18c, 40c. Therefore, it is not necessary to provide a pump such as the pump 36 of the device 10 at these outlets to force LNG out of the buffer tanks 18, 40.

The fuel gas supply device has two main functions described below.
-The fuel gas is supplied from the main tank 14 to the equipment 12 of the ship at a desired required flow rate (for example, 50 kg/h to 2000 kg/h), a predetermined pressure (for example, 6 bar to 300 bar), and a predetermined temperature (for example, 20°C). .. The fuel gas may have a gas form (vapor) or a liquid form.
-Adjust the pressure in the main tank 16 within an acceptable range (e.g. -100 mbarg to +700 mbarg).

The described apparatus 10 comprises, for example, a main tank 16 designed to contain a cryogenic liquid at atmospheric pressure (for example having a capacity of 1000 m ^{3 to} 10000 m ³ and an approved pressure of −100 mbarg to +700 mbarg) and a cryogenic temperature. A buffer tank 18 intended to contain a liquid (for example having a capacity of 1 m ^{3 to} 20 m ³ and an allowable pressure of −500 mbar to 6000 mbar). The compressor 20 has a pressure difference between the main tank 16 and the buffer tanks 18, 40 so that the liquid can be transferred from the main tank 16 to the buffer tanks 18, 40 (for example, +500 mbarg for the main tank with respect to the buffer tank). Cause The liquid in the buffer tanks 18 and 40 is sent to the facility 12 via the boil-off valve 33b. The level of liquid in each buffer tank is controlled using suitable equipment, for example 10% to 90% of the capacity of the buffer tank.

The manner in which the device is controlled, and the appropriate equipment, is designed to maintain the pressure in the main tank 16 at the required level (eg, -100 mbarg to 700 mbarg). Thus, advantageously, each tank of the device 110 is provided with a pressure sensor and/or a level sensor.

8 to 12 show the operating phases of the device of FIG. These operating phases may correspond to the operating phases of a ship equipped with the device.

The liquefied gas cooling method will be described in the following four operating phases.
1. Minimum Consumption: Natural boil-off covers the energy demand of facility 12 . The ship's propulsion engine is off or operating at low load, and the gas is used primarily to meet the needs of electricity and heating .
2. Normal consumption: Natural boil-off does not cover the ship's energy needs.
3. No consumption (all gas consuming elements mounted on the facility 12 except the gas compressor are stopped).
4. filling.

This is a continuous method in which the buffer tanks 18 and 40 are alternately filled and emptied. Only the filling and draining of the tank 18 will be described intensively, but the process for the tank 40 is symmetrical thereto.

1. Minimum consumption (see Figure 8)

In the operation phase shown 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 to 3 MW).

The evaporation of LNG 16aa in the tank 16 increases the pressure of the BOG 16ab in the tank 16. The BOG 16ab is sucked by the compressor 20, heated by the exchanger 28, and sent to the facility 12. This allows the pressure in tank 16 to be maintained below an acceptable threshold.

The following operations are possible to adjust the pressure in the tank 16.
Adjusting the flow rate of the BOG sent to the compressor 20 (if the flow rate is higher than the natural boil-off speed, the pressure in the tank 16 drops; if the flow rate is lower than the natural boil-off speed, the pressure in the tank rises).
Re-inject some of the compressed gas (exiting the compressor 20) into the main tank 16 (e.g. due to the specifications of the compressor 20 the input flow rate of the compressor is reduced below a certain value (here greater than the natural boil-off speed)) If this is not possible, some of the compressed gas is reinjected into the tank 16 via the pipe 38.

Thus, the device 10 supplies the required amount to the facility 12 with the gas coming from the tank 16 and maintains the pressure inside the tank at the required level (e.g. -100 mbarg to 700 mbarg).

2. Normal consumption

In the second phase of operation, consumption is normal.

The natural boil-off in tank 16 is insufficient to meet the energy demand of facility 12. Forced boil-off is required to meet the ship's energy needs. This phase includes the following two steps.
-Preparation for forced boil-off: Fill buffer tank 18 with liquefied natural gas from tank 16.
-Forced evaporation: the liquid from the buffer tank 18 is sent to the exchanger and then to the installation (while filling the other buffer tank 40 with LNG).

-Preparation for forced evaporation (Fig. 9)

The first step is to reduce the pressure in the buffer tank 18 and/or increase the pressure in the tank 16 to cause a pressure difference of, for example, -500 mbar between the main tank 16 and the buffer tank 18. Consists of. The pressure in tank 16 may be increased as described in the first phase. The pressure in the buffer tank 18 can be lowered by sucking the natural gas in the buffer tank by the compressor 20. Due to this pressure difference (-500 mbar), LNG can be sucked from the tank 16 from a height of approximately 10 m.

When the pressure rises in the tank 16, the BOG from the tank 16 forces LNG to flow out of the tank and flow through the pipe 22 to the buffer tank 18. When the pressure drops in the buffer tank 18, the LNG contained in the tank 16 is sucked into the tank 18. The pressure difference contributes to the partial boil-off of LNG in the tank 18. The boil-off gas is sucked by the compressor 20 so that the pressure difference between the tanks 16, 18 can be maintained. The tank 18 is filled with liquefied natural gas, for example up to 90% of its capacity. These operations may be combined with the first operation phase to adjust the pressure in the tank 16.

-Forced evaporation (Fig. 10)

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

The tank 18 is filled with liquid and the pipe 22 and valve 23b used to draw natural gas from the tank are closed. The compressed gas exiting the compressor 20 is sent to the tank 18 (a part thereof if necessary) and is pressurized. This may force LNG from the tank 18 to flow through the exchanger 34 and the facility 12.

While LNG is being supplied from tank 18 to facility 12, tank 40 is filled with LNG from tank 16 (thus, only valves 23d and 23e are closed and valves 23b and 23f are open). Advantageously, the device 110 is designed such that the compressor 20 can be used to fill the tank 40 at a faster rate than LNG is discharged from the tank 18.

The flow rate and pressure of LNG at the outlet of the buffer tank 18 are adjusted by the valve 33b. The tank 18 is used until its LNG level is sufficiently low (eg 5% of its capacity). From this point, the tank 40 can supply LNG to the facility 12 more. Then, as described in the first step, the tank 16 is filled with LNG.

Therefore, in this phase, the tanks 18, 40 are alternately filled with LNG and compressed using the compressor 20 to supply LNG to the facility 12.

These operations may be combined with the first operation phase to adjust the pressure in the main tank 16.

3. No consumption (see Figure 11)

This operating phase is activated in an emergency. The facility 12 is stopped. That is, there is no consumption of fuel gas. The exchanger 28 and the compressor 20 are operated by an emergency generator.

In this phase, it is assumed that the tanks 16 and 18 contain LNG. A compressor 20 is used to deliver compressed gas to the tank 18 to raise the pressure within the tank. As a result, the LNG is forcibly discharged from the tank and directed toward the manifold 52, so that the LNG is sprayed onto the BOG in the tank 16. As a result, the BOG in the tank 16 can be condensed, so that the pressure reduction and the pressure maintenance in the main tank 16 are realized.

Therefore, the pressure in the tank 16 is adjusted by the flow rate of LNG coming from the buffer tank 18 and sprayed by the manifold 52.

When the tank 18 is empty, this operation is repeated using the tank 40, during which the tank 18 is refilled.

This operating phase may be combined with the first or second phase to reduce the pressure in the main tank 16.

4. Filling (see Figure 12)

The valve 23d is opened. LNG from the filling station is sent to tank 16. BOG boiled off during filling is discharged by opening valves 31a and 31c as well, forming a free flow of BOG to the station.

FIG. 13 shows a modified embodiment of the device 210 according to the invention. This variant embodiment differs from the device 110 in particular in that it includes a pump 36.

The features described above with reference to apparatus 110 apply to apparatus 2110 unless they are consistent with the description below.

The pump 36 is arranged in the pipe 54. The upstream end of the pipe 54 connects to the outlets 18c, 40c of the tanks 18, 40 immediately downstream of their valves. The downstream end of the pipe 54 is connected to the pipe 32 immediately upstream of the valve 33b. The pipe 54 includes a valve 56 and extends parallel to a portion of the pipe 32. The pipe 32 includes a further valve 58. This configuration provides the option of using or not using the pump 36 to drain the LNG contained in the tanks 18, 40 and send it to the spray manifold 525 and/or the facility 12. provide.

Therefore, the device operates in a hybrid manner with respect to the device 10, 110.

Claims (39)

A device (10, 110, 210) for supplying a fuel fluid to a power generation facility (12) mounted on a ship (14),
-Main liquefied gas tank (16),
-At least one first liquefied gas buffer tank (18),
A first pipe (32) for transferring a liquefied gas from the first buffer tank (18) to the facility (12), wherein the first end (32a) of the first pipe (32) is A first pipe (opens into a first buffer tank (18) and a second end (32b) of the first pipe (32) connects to the facility (12) to supply fuel fluid to the facility (12). 32),
A second pipe (22) for transferring a liquefied gas from the main tank (16) to the first buffer tank (18), the liquefied gas (24) contained in the main tank (16); A first end (22a) intended to be immersed in the first buffer tank, and a second end (22b) opening into the first buffer tank (18) for supplying liquefied gas to the first buffer tank; A second pipe (22) having
-Means (20, 36) for lowering the pressure in the first buffer tank (18) with respect to the main tank (16), which sucks the fluid in the first buffer tank and By applying an operating pressure lower than the pressure in the main tank to the buffer tank, the liquefied gas is transferred from the main tank (16) through the second pipe (22) to the first buffer tank (18). Means (20, 36) configured to supply;
In a device (10, 110, 210) including
Said decompression means comprises at least one compressor (20),
The operating pressure is below atmospheric pressure,
An apparatus (10, 110, 210) characterized by the above. Said decompression means has an outlet (20b) intended to connect to said installation (12),
Device (10, 110, 210) according to the preceding claims. A pump is connected to the first pipe and configured to draw liquefied gas from the first buffer tank,
Device (10, 110, 210) according to any one of the preceding claims. The compressor (20) is connected to a third pipe (26) to reduce the pressure in the first buffer tank (18),
A first end (26a) of the third pipe (26) opens into the first buffer tank (18),
The second end (26b) of the third pipe (26) connects to the inlet (20a) of the compressor,
The third pipe is configured to suck the boil-off gas in the first buffer tank and supply the boil-off gas to the compressor.
Device (10, 110, 210) according to the preceding claims. The compressor (20) has an outlet (20b) that connects to the facility to supply fuel gas to the facility,
Device (10, 110, 210) according to the preceding claims. The second end of the third pipe is connected to the compressor by a first circuit of a heat exchanger,
Device (10, 110, 210) according to claim 4 or 5. The device includes a fourth pipe for transferring gas from the main tank to the compressor,
Device (10, 110, 210) according to any one of the preceding claims. The fourth pipe has a first end opening to the main tank and a second end connecting to the compressor.
Device (10, 110, 210) according to the preceding claims. The second end of the fourth pipe is connected to the inlet of the first circuit of the heat exchanger by the second pipe, and the outlet of the heat exchanger is connected to the compressor,
Device (10, 110, 210) according to the preceding claims. The first end (22a) of the second pipe (22) has no pump,
Device (10, 110, 210) according to any one of the preceding claims. The first pipe includes at least a pump, and/or a pressure reducing valve, and/or a heat exchanger,
Device (10, 110, 210) according to any one of the preceding claims. The pump is configured to be controlled according to the fuel gas demand of the facility,
Device (10, 110, 210) according to the preceding claims. The apparatus includes a fifth pipe for returning fluid from the decompression means to the main tank,
The first end of the fifth pipe is connected to the outlet of the pressure reducing means,
A second end of the fifth pipe opens into the main tank,
Device (10, 110, 210) according to any one of the preceding claims. Including a second liquefied gas buffer tank (40),
Device (110, 210) according to any one of the preceding claims. The second buffer tank (40)
-The first pipe (32), the first pipe (32) having a third end (32c) opening to the second buffer tank (40);
-The second pipe (22), which has a third end (22c) opening to the second buffer tank (40);
Connect to,
Device (110, 210) according to the preceding claims. The buffer tank (40) is connected to the third pipe (26),
The third pipe (26) has a third end (26c) opening to the second buffer register (40),
Device (110, 210) according to the preceding claims when dependent on claim 4 or 10. The apparatus includes a fifth pipe (42) for supplying gas to the first buffer tank (18) and the second buffer tank (40),
The first end (42a) of the fifth pipe (42) is connected to the outlet (20b) of the pressure reducing means (20),
A second end (42b) of the fifth pipe (42) opens into the first buffer tank (18),
A third end (42c) of the fifth pipe (42) opens into the second buffer tank (40),
The fifth pipe is configured to supply compressed gas to the first buffer tank and/or the buffer tank.
Device (110, 210) according to claim 14 or 15. The first pipe is connected to a manifold for spraying liquefied gas into the main tank by a sixth pipe,
The manifold is configured to spray a liquefied gas in a droplet state onto a boil-off gas in the main tank to condense at least a part of the boil-off gas.
Device (10, 110, 210) according to any one of the preceding claims. Each tank is provided with a pressure sensor and/or a level sensor,
Device (10, 110, 210) according to any one of the preceding claims. The or each buffer tank is arranged below the upper end of the main tank,
Device (10, 110, 210) according to any one of the preceding claims. The or each buffer tank is arranged outside the main tank,
Device (10, 110, 210) according to any one of the preceding claims. The or each buffer tank may have an expansion and/or separation function,
Device (10, 110, 210) according to any one of the preceding claims. The main tank is a membrane type,
Device (10, 110, 210) according to any one of the preceding claims. The main tank is configured to withstand a pressure of 3000 mbarg or less, preferably 750 mbarg or less,
Device (10, 110, 210) according to the preceding claims. Ship, in particular for transporting liquefied gas, comprising at least one device (10, 110) according to any one of the preceding claims. A method for supplying fuel by means of a device (10) according to any one of the preceding claims, in particular to an energy production facility (12) on board a ship (14),
Transferring the liquefied gas from the main tank (16) to the first buffer tank (18) by lowering the pressure in the first buffer tank (18) with respect to the main tank (16), Comprising step A of filling the first buffer tank (18),
A method characterized by the following. The device is defined in claim 5;
-Comprising step B1 of sucking the gas in the first buffer tank (18) by the compressor (20) and supplying it to the facility (12),
The method according to the preceding claims. The device is further defined in claim 17,
The facility by supplying gas to the first and/or second buffer tanks (18, 40) by the compressor (20) to force liquefied gas to flow through the first pipe (32) Including step B2 of supplying to (12),
The method according to claim 26 or 27. In step B1 or B2, the compressor (20) lowers the pressure in the second buffer tank (40) with respect to the main tank (16), so that the liquefied gas is discharged from the main tank (16) to the second tank. Transferring to a buffer tank (40) and supplying liquefied gas to the second buffer tank (40),
The method according to the preceding claims. In step A, the pressure in the main tank is controlled by adjusting the flow rate of the gas flowing through the fourth pipe and/or the fifth pipe,
30. A method according to any one of claims 26 to 29. Liquefied gas is supplied from the first buffer tank to the pump of the first pipe in step A or after step A,
31. A method according to any one of claims 26 to 30. Supplying the equipment via the first pipe by operating the pump, B3,
The method according to any one of claims 26 to 31. In step A, the reduced pressure is continuously maintained for a predetermined time,
33. A method according to any one of claims 26 to 32. A pressure difference between the buffer tank (18) and the main tank (16), which is determined by a substantially linear vertical height of the second pipe after subtracting a head loss in the second pipe as necessary. Reducing the pressure by applying a pressure differential greater than the hydrostatic pressure generated,
The method according to any one of claims 26 to 33. The pump is controlled according to the fuel gas demand of the facility,
Method according to any one of claims 26 to 34. At least some of the valves provided on one or more of the pipes are controlled according to the fuel gas demand of the installation,
The method according to any one of claims 26 to 35. When the liquefied gas level in the buffer tank falls below a predetermined threshold level, the pressure difference between the buffer tank and the main tank is immediately increased to increase the flow rate of the liquefied gas supplied from the buffer tank. ,
37. A method according to any one of claims 26 to 36. The pressure difference between one of the buffer tanks and the main tank is adjusted according to the rate at which the other buffer tank is filled with liquefied gas from the main tank,
38. A method according to any one of claims 26 to 37. The liquefied gas stored in the first buffer tank is sent to the spray manifold through the first and sixth pipes,
The method according to any one of claims 26 to 38.

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