EP3714201A1

EP3714201A1 - Device and method for providing liquefied natural gas

Info

Publication number: EP3714201A1
Application number: EP18819541.6A
Authority: EP
Inventors: Hicham GUEDACHA; Hugues MALVOS; Yacine ZELLOUF
Original assignee: Engie SA
Current assignee: Engie SA
Priority date: 2017-11-24
Filing date: 2018-11-22
Publication date: 2020-09-30
Also published as: FR3074254A1; US20200370709A1; KR20200093571A; SG11202005304VA; CN111630312A; CN111630312B; FR3074254B1; WO2019102155A1

Abstract

The device (100) for providing liquefied natural gas, referred to as LNG, comprises: - an evaporation gas buffer tank (105) comprising an inlet (110) for evaporation gas suitable for receiving evaporation gas from a third-party device, - a member (115) for transferring evaporation gas from the buffer tank to an LNG storage capacity (120), - downstream from the transfer member (120), a compressor (140) for compressing the evaporation gas, - an evaporation gas transfer pipe (125) for transferring evaporation gas from the transfer member to the storage capacity, - the LNG storage capacity, - an LNG transfer pipe (130) for transferring LNG from the storage capacity to a third-party device and - a heat exchanger (135) for exchanging heat between evaporation gas passing through the evaporation gas transfer pipe and LNG passing through the LNG transfer pipe configured to liquefy or cool the evaporation gas.

Description

DEVICE AND METHOD FOR PROVIDING LIQUEFIED NATURAL GAS

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a device and a method for supplying LNG. It applies in particular to the field of LNG bunkering suitable for land and sea vehicles.

STATE OF THE ART

The use of liquefied natural gas (hereinafter referred to as "LNG") as a road or marine fuel is in full development, boosted by the environmental and economic benefits that LNG provides in comparison to other fossil fuels.

In general, LNG service stations consist of an LNG receiving system, a cryogenic storage system for storing LNG in the sub-cooled state, with operating pressure generally between 7 and 9 bar, a cryogenic pump for transferring the LNG and a distribution system to supply the vehicle.

Today, three categories of vehicles are likely to stock up on LNG:

a first category feeding with cold LNG (or "cold LNG"), that is to say having a pressure of 3 bar,

- a second category feeding on "saturated LNG" (LNG) with a pressure of 8 bar and

- a third category feeding LNG called "super saturated" (or "super saturated LNG") with a pressure of 18 bar.

Today, vehicles with a pressure of 8 bar are the majority. The vaporization of the LNG created by BOG, for "Boil-off gas" or evaporation gas in French, is relatively important during the full vehicles 8 bar and 18 bar. Vehicle tanks have been sized to withstand pressure surges, but the design of these equipment is nevertheless limited by a maximum allowable pressure. A gas return from the vehicle to the station is then made to avoid reaching this maximum pressure leading thereafter a significant release of gas into the atmosphere.

This gas return within the LNG storage represents a source of heat for LNG, which favors the evaporation of LNG and thus the increase of the pressure inside the storage. These evaporations or BOG must be managed without being released to the atmosphere.

In addition to the generated product losses, this adds to the operational complexity of the site.

In addition, the LNG stored in the storage tank of the service station is generally in the subcooled state. The heat source used to bring the LNG to saturation (at 8 bar and 18 bar) comes from the open air, requiring the installation of large heat exchanger surface on site.

On the other hand two methods exist to provide fuel LNG for 8 and 18 bar vehicles:

- the "Bulk saturation" method which consists in storing the LNG at saturation and

- a method of using a "LNG saturation on the fly" conditioning which aims to supply saturated LNG from sub-cooled LNG.

In the case of compressed LNG service stations, or GNLC, the storage of the gas return is known to be in a buffer tank for CNG use. Some LNG stations accept the return of gas and are not concerned about its impact on BOG generation. These stations are usually equipped with a BOG liquefaction system.

Current solutions using air vaporizers are used to obtain saturated LNG, requiring substantial exchange surfaces and a large footprint.

So-called "saturation on the fly" systems have the drawbacks of requiring high-performance and expensive exchangers and require a very complex control system, which raises a problem of operational stability.

Finally, bulk saturation systems can not provide vehicles operating at a pressure of 3 bar and have a reduced storage capacity and storage time. It should be noted that in the case of stations equipped with BOG liquefaction systems, these systems are expensive and have no possible return on investment.

OBJECT OF THE INVENTION

The present invention aims to remedy all or part of these disadvantages.

For this purpose, according to a first aspect, the present invention aims a device for supplying liquefied natural gas, called "LNG", which comprises:

a buffer tank of evaporation gas comprising an inlet for evaporation gas adapted to receive evaporation gas from a third device,

an evaporation gas transfer member of the buffer tank to an LNG storage capacity,

downstream of the transfer member, a compressor of the evaporation gas,

an evaporation gas transfer line from the transfer member to the storage capacity,

- the storage capacity of LNG,

an LNG transfer line from the storage capacity to a third party device and

a heat exchanger between evaporation gas passing through the evaporation gas transfer pipe and LNG passing through the LNG transfer pipe configured to liquefy or cool the evaporation gas.

With these provisions, the evaporation gas transferred from the buffer tank to the storage capacity is liquefied, which keeps the LNG stored in the capacity at a low temperature limiting the formation of BOG within this capacity.

These arrangements also improve the performance of the device in liquefying the evaporation gas.

In embodiments, the transfer member is a valve controlled as a function of a pressure value inside the detected buffer tank, by a pressure sensor, or a discharger.

In embodiments, the evaporation gas and the LNG flow countercurrently within the heat exchanger. These embodiments improve the performance of the device in liquefying the evaporation gas.

In embodiments, the buffer tank has a higher operating pressure value of at least two bar than the operating pressure value of the storage capacity.

These embodiments allow a natural flow of the evaporation gas from the buffer tank to the storage capacity.

In embodiments, the device which is the subject of the present invention comprises, downstream of the heat exchanger, a deviation of the liquefied or cooled evaporation gas transfer line in the heat exchanger, the gas supply of deviation evaporation being controlled according to a temperature sensed by a temperature sensor of the evaporation gas at the outlet of the heat exchanger.

These embodiments make it possible to recycle evaporation gas that does not reach a determined temperature value.

In embodiments, the device that is the subject of the present invention comprises, on the deviation, a first valve and, on the evaporation gas transfer line downstream of the deflection, a second valve, the opening of the first or the second valve being controlled according to the sensed evaporation gas temperature.

In embodiments, the device of the present invention comprises a liquefied evaporation gas transfer member from the buffer tank to the LNG transfer line.

These embodiments make it possible to saturate the transferred LNG with the third-party device.

In embodiments, the device that is the subject of the present invention comprises:

a pipe for extracting evaporation gas inside the storage capacity,

a compressor of the evaporation gas passing through the extraction pipe and

a pipe for supplying compressed evaporation gas to the buffer tank. These embodiments make it possible to minimize the storage volume required by the buffer tank.

In embodiments, the evaporation gas compressor has the evaporative gas inlet adapted to receive evaporation gas from a third-party device.

In embodiments, the device that is the subject of the present invention comprises means for cooling the flow of evaporation gas downstream of the transfer member.

These embodiments make it possible to cool or liquefy part or all of a flow of evaporation gas at the outlet of the heat exchanger.

In embodiments, the device which is the subject of the present invention comprises, downstream of the heat exchanger, a gas flow expander configured to relax the flow of evaporation gas at a determined pressure.

In embodiments, the device which is the subject of the present invention comprises, downstream of the expander, a gas / liquid separator, the gaseous evaporation gas being supplied to the deflection and the liquid evaporation gas being supplied to the cooling capacity. storage.

According to a second aspect, the present invention relates to a process for supplying liquefied natural gas, called "LNG", which comprises:

a step of storing evaporation gas from a third device in an evaporation gas buffer tank comprising an inlet for evaporation gas adapted to receive evaporation gas from a third device,

a step of transfer of evaporation gas from the buffer tank to an LNG storage capacity,

downstream of the transfer step, a step of compression of the evaporation gas,

a step of heat exchange between the evaporation gas transferred and LNG transferred to a third device resulting from the LNG storage capacity for liquefying or cooling the evaporation gas,

a storage step of LNG in the storage capacity,

a step of transferring LNG from the storage capacity to a third-party device. Since the aims, advantages and particular characteristics of the method which are the subject of the present invention being similar to those of the device which is the subject of the present invention, they are not recalled here. BRIEF DESCRIPTION OF THE FIGURES

Other advantages, aims and particular characteristics of the invention will emerge from the following nonlimiting description of at least one particular embodiment of the device and method that are the subject of the present invention, with reference to the appended drawings, in which:

FIG. 1 represents, schematically, a first particular embodiment of the device that is the subject of the present invention,

FIG. 2 represents, schematically and in the form of a logic diagram, a particular sequence of steps of the method which is the subject of the present invention and

- Figure 3 shows schematically a second particular embodiment of the device object of the present invention.

DESCRIPTION OF EXAMPLES OF CARRYING OUT THE INVENTION

This description is given in a nonlimiting manner, each feature of an embodiment being able to be combined with any other feature of any other embodiment in an advantageous manner.

It is already noted that the figures are not to scale.

Subsequently, the term "third party device", any device consuming LNG to produce energy. Such a third party device is, for example, a land, sea, river or air vehicle.

FIG. 1, which is not to scale, shows a schematic view of an embodiment of the device 100 which is the subject of the present invention. This device 100 for supplying liquefied natural gas, called "LNG", comprises:

an evaporation gas buffer reservoir 105 having an inlet 110 for evaporation gas adapted to receive evaporation gas from a third device,

a member 120 for transfer of evaporation gas from the buffer tank to a storage capacity 115 of LNG,

a pipe 125 for transfer of evaporation gas from the transfer member to the storage capacity, - the storage capacity of LNG,

a pipe 130 for transferring LNG from the storage capacity to a third-party device and

a heat exchanger 135 between evaporation gas passing through the evaporation gas transfer pipe and LNG passing through the LNG transfer pipe configured to liquefy or cool the evaporation gas.

The reservoir 105 is, for example, an evaporation gas storage volume designed to retain a predetermined amount of evaporation gas in a given pressure range. The inlet 110 is, for example, an orifice made in the storage volume and configured to receive an injection member of the evaporation gas into the volume. Such an injection member is, for example, a nozzle or a one-way valve.

This reservoir 105 is configured, for example, to operate at an operating pressure greater than 11 barg.

This tank 105 has, for example, a capacity of one cubic meter and the capacity 115 has, for example, a capacity of eighty cubic meters.

The inlet 110 is preferably connected to a connector with the third device configured to collect the return of evaporation gas. The type of connector depends on the standard used by the third-party device and the purpose of the device 100 envisaged.

The supply of evaporation gas from the third device to the reservoir 105 is carried out, for example, by pressure gradient.

This reservoir 105 is provided, preferably in the upper part, with an evaporation gas outlet connected to the transfer member 115. The transfer member 115 is, for example, a discharger or a valve controlled as a function of a pressure value sensed inside the tank 105. This pressure value is sensed, for example, by a pressure sensor 145. . When the sensed pressure is higher than a setpoint, the valve is open.

The choice of this setpoint value is arbitrary and fixed by the operator. It depends on the design and cost objectives of the station. A set pressure of 15 or 16 bar if the station is sized to supply vehicles operating at 18 bar can be implemented, for example. The gas transfer line 125 connects the transfer member 115 to the storage capacity 115. Preferably, the device 100 comprises, downstream of the transfer member 120, a compressor 140 or a booster.

Such a compressor 140 is, for example, an alternating compressor, reciprocating compressor type preferably piston.

At the output of the compressor 140 or the booster, the gas has a sufficient pressure to overcome the pressure losses of the circuit and allow the recycle to be realized. The choice of discharge pressure is set according to the sizing objectives of the station and the operating mode desired by the operator.

The evaporation gas, compressed or not by the compressor 140 as a function of the presence of this compressor 140 in the device 100, passes through the heat exchanger 135.

The heat exchanger 135 is, for example, a fin or plate exchanger between the evaporation gas passing through the transfer line 125 and the LNG passing through the transfer line 130. The evaporation gas acts as a hot fluid and the LNG as a cold fluid so that the outlet temperature of the evaporation gas is colder than the inlet temperature of the evaporation gas in the exchanger. thermal. Preferably, the heat exchanger 135 is designed so that the evaporation gas is liquefied or cooled at the outlet of the heat exchanger 135 for specific flow rates of LNG and evaporation gas.

The heat exchanger 135 is also designed to preferentially heat the LNG to a predetermined temperature. Depending on said temperature, the flow rate of gas passing through the transfer line 125 is adjusted. If the LNG temperature is to be increased, the gas transfer rate in line 125 is increased.

Preferentially, the LNG and evaporation gas circulate in counter-current so as to optimize the heat exchange between the two fluids.

Storage capacity 115 is, for example, an evaporation gas storage volume designed to hold a predetermined amount of LNG within a specified pressure range. The capacity 115 preferably comprises an inlet for liquefied evaporation gas. This input is, for example, an orifice made in the storage capacity and configured to receive a gas injection member of liquefied evaporation in the volume. Such an injection member is, for example, a nozzle or a one-way valve.

The capacity 115 is configured to operate, for example, at an operating pressure of between 7 and 9 bar.

Preferably, the operating pressure inside the storage capacity 115 is at least two bars less than the operating pressure inside the buffer reservoir 105.

The capacity 115 is provided with an output for LNG, preferably in the lower part, connected to the transfer line 130.

The transfer line 130 is connected to a connector whose nature depends on the type of third party device connected to the device 100.

In variants, the device 100 comprises a pump 116 configured to facilitate the transfer of the LNG from the capacity 115 to the third device.

In preferred embodiments, such as that shown in FIG. 1, the device 100 comprises, downstream of the heat exchanger 135, a deflection

150 of the liquefied or cooled evaporation gas transfer line 125 in the heat exchanger, the supply of evaporation gas to the deflection being controlled according to a temperature sensed by a gas temperature sensor 155; evaporation at the outlet of the heat exchanger.

In preferred embodiments, such as that shown in FIG.

1, the device 100 comprises, on the deflection 150, a first valve 160 and, on the evaporation gas transfer line 125 downstream of the deflection, a second valve 165, the opening of the first or the second valve being controlled according to the sensed evaporation gas temperature.

When the evaporation gas has a temperature below a predetermined threshold value, the first valve 160 is open and the second valve 165 closed. Conversely, when the evaporation gas has a temperature greater than the predetermined threshold value, the first valve 160 is closed and the second valve 165 open.

In preferred embodiments, such as that shown in FIG.

1, the device 100 comprises a liquefied evaporation gas transfer member 170 from the buffer tank 105 to the LNG transfer line 130. The member 170 is, for example, a valve controlled according to the pressure sensed inside the storage tank 105 by a pressure sensor 171.

FIG. 3, which is not to scale, shows a schematic view of an embodiment of the device 200 which is the subject of the present invention. This device 200 for supplying liquefied natural gas, called "LNG", comprises:

a member 115 for transferring evaporation gas from the buffer tank to a storage capacity 120 for LNG,

downstream of the transfer member 120, a compressor 140 of the evaporation gas,

a pipe 125 for transfer of evaporation gas from the transfer member to the storage capacity,

- the storage capacity of LNG,

The reservoir 105 is, for example, configured to operate at an operating pressure greater than 30 bar.

The inlet 110 is preferably connected to a connector with the third device configured to collect the return of evaporation gas. The type of connector depends on the standard used by the third-party device and the purpose of the device 200 envisaged.

The supply of evaporation gas from the third device to the tank 105 is carried out, for example, by pressure gradient or through the use of a booster.

The set-point value is chosen, for example, to correspond to the maximum operating pressure of the capacity 105. It should be noted that the operator can also allow remote gas transfer without this maximum pressure being reached, if necessary, by a second all-or-nothing valve, for example.

The gas transfer line 125 connects the transfer member 115 to the storage capacity 115. Preferably, the device 200 comprises, downstream of the transfer member 120, a compressor 140.

At the output of the compressor 140 the gas has, for example, a pressure greater than or equal to 50 bar.

The evaporation gas, compressed or not by the compressor 140 as a function of the presence of this compressor 140 in the device 200, passes through the heat exchanger 135.

In embodiments, such as that shown in Figure 3, the device 200 comprises a means 126 for cooling the evaporation gas flow downstream of the transfer member 120. This means 126 for cooling is, for example, a heat exchanger using liquid nitrogen as a cold fluid. At the outlet of the heat exchanger 135, the flow of evaporation gas is preferably two-phase, that is to say partially liquid and partly gaseous, or more generally cooled. This stream can be injected into the storage capacity 115.

In embodiments, such as that represented in FIG. 3, the device 200 comprises, downstream of the heat exchanger 135, a regulator 136 of the gas flow configured to relax the flow of evaporation gas at a predetermined pressure.

In embodiments, such as that shown in FIG. 3, the device 200 comprises, downstream of the expander 136, a gas / liquid separator 137, the gas evaporation gas being supplied at the deflection 150 and the evaporation gas liquid being supplied to the storage capacity 115.

The separator 137 is, for example, a separation flask.

Storage capacity 115 is, for example, an evaporation gas storage volume designed to hold a predetermined amount of LNG within a specified pressure range. The capacity 115 preferably comprises an inlet for liquefied evaporation gas. This inlet is, for example, an orifice made in the storage capacity and configured to receive an injection member of the liquefied evaporation gas into the volume. Such an injection member is, for example, a nozzle or a one-way valve.

The capacity 115 has, for example, an operating pressure value of between 7 and 9 bar.

Preferably, the operating pressure inside the storage capacity 115 is at least two bars less than the operating pressure inside the buffer reservoir 105. The capacity 115 is provided with an output for LNG, preferably in the lower part, connected to the transfer line 130.

The transfer line 130 is connected to a connector whose nature depends on the type of third party device connected to the device 200.

In variants, the device 200 comprises a pump 116 configured to facilitate the transfer of the LNG from the capacity 115 to the third device.

In preferred embodiments, such as that shown in FIG. 3, the device 200 comprises, downstream of the heat exchanger 135, a deflection 150 of the liquefied or cooled evaporation gas transfer line 125 in the exchanger thermal, the supply of evaporation gas to the deflection being controlled according to a temperature sensed by a temperature sensor 155 of the evaporation gas at the outlet of the heat exchanger.

In preferred embodiments, such as that shown in Figure 3, the device 200 comprises, on the deflection 150, a first valve 160 and, on the evaporation gas transfer line 125 downstream of the deflection, a second valve 165, the opening of the first or the second valve being controlled according to the sensed evaporation gas temperature.

In preferred embodiments, such as that shown in Figure 3, the device 200 comprises a liquefied evaporation gas transfer member 170 from the buffer tank 105 to the LNG transfer line 130.

The member 170 is, for example, a valve controlled according to the pressure sensed inside the storage tank 105 by a pressure sensor 171.

In preferred embodiments, such as that represented in FIG. 3, the device 200 comprises:

a pipe 205 for extracting evaporation gas inside the storage capacity 115,

a compressor 210 of the evaporation gas passing through the extraction pipe and a line 215 for supplying the compressed evaporation gas to the buffer tank 105.

The pipe 205 is preferably connected in the upper part of the storage capacity 115.

The compressor 210 is configured to, for example, increase the pressure of the gas to a value greater than 30 bar.

In preferred embodiments, such as that shown in FIG. 3, the evaporation gas compressor 210 comprises the inlet 110 for evaporation gas adapted to receive evaporation gas coming from a third device.

FIG. 2 diagrammatically shows a particular embodiment of the method 300 which is the subject of the present invention. This method 300 for supplying liquefied natural gas, called "LNG", characterized in that it comprises:

a step 305 for storing evaporation gas from a third device in an evaporation gas buffer tank comprising an inlet for evaporation gas adapted to receive evaporation gas from a third device,

a step 310 of evaporation gas transfer from the buffer tank to an LNG storage capacity,

downstream of the transfer step 310, a compression step 330 of the evaporation gas,

a step 315 of heat exchange between the evaporation gas transferred and LNG transferred to a third device resulting from the LNG storage capacity for liquefying or cooling the evaporation gas,

a step 320 for storing LNG in the storage capacity,

a step 325 of LNG transfer from the storage capacity to a third party device.

The operation of this method 200 is carried out, for example, by the implementation of the devices, 100 and 300, as described with reference to FIGS. 1 and 3, all the variants and embodiments of the devices 100 and 300 being able to to be transposed as process steps 200.

Claims

1. Device (100, 200) for supplying liquefied natural gas, called "LNG", characterized in that it comprises:

an evaporation gas buffer tank (105) comprising an inlet (110) for evaporation gas adapted to receive evaporation gas from a third device,

a member (120) for transferring evaporation gas from the buffer tank to a storage tank (115) for LNG,

downstream of the transfer member (120), a compressor (140) of the evaporation gas,

a conduit (125) for transferring evaporation gas from the transfer member to the storage capacity,

- the storage capacity of LNG,

a pipe (130) for transferring LNG from the storage capacity to a third-party device and

a heat exchanger (135) between evaporation gas passing through the evaporation gas transfer pipe and LNG passing through the LNG transfer pipe configured to liquefy or cool the evaporation gas.

2. Device (100, 200) according to claim 1, wherein the transfer member (120) is a valve controlled according to a pressure value inside the buffer reservoir (105) detected by a sensor. (145) pressure, or a discharge.

3. Device (100, 200) according to one of claims 1 or 2, wherein the evaporation gas and LNG circulate against the current inside the heat exchanger (135).

4. Device (100, 200) according to one of claims 1 to 3, wherein the buffer reservoir (105) has a higher operating pressure value of at least two bar at the operating pressure value of the capacity (115). ) storage.

5. Device (100, 200) according to one of claims 1 to 4, which comprises, downstream of the heat exchanger (135), a deflection (150) of the pipe (125) for the transfer of evaporation gas liquefied or cooled in the heat exchanger, the supply of evaporation gas to the deflection being controlled according to a temperature sensed by a sensor (155) of temperature of the evaporation gas at the outlet of the heat exchanger.

6. Device (100, 200) according to claim 5, which comprises, on the deflection (150), a first valve (160) and, on the pipe (125) of evaporation gas transfer downstream of the deflection, a second valve (165), the opening of the first or the second valve being controlled according to the sensed evaporation gas temperature.

7. Device (100, 200) according to one of claims 1 to 6, which comprises a member (170) for transferring liquefied evaporation gas from the reservoir (105) buffer to the pipe (130) LNG transfer .

8. Device (200) according to one of claims 1 to 7, which comprises:

a pipe (205) for extracting evaporation gas inside the storage capacity (115),

a compressor (210) of the evaporation gas passing through the extraction pipe and

a line (215) for supplying the compressed evaporation gas to the buffer tank (105).

9. Device (200) according to claim 8, wherein the compressor (210) of evaporation gas comprises the inlet (110) for evaporation gas adapted to receive evaporation gas from a third device. 10. Device (200) according to one of claims 1 to 9, which comprises a means

(126) for cooling the evaporation gas stream downstream of the transfer member (120).

11. Device (200) according to claim 10, which comprises, downstream of the heat exchanger (135), an expander (136) of the gas flow configured to relax the flow of evaporation gas at a predetermined pressure. 12. Device (200) according to claim 11 and claim 5, which comprises, downstream of the expander (136), a gas / liquid separator (137), the gaseous evaporation gas being supplied to the deflection (150) and the liquid evaporation gas being supplied to the storage capacity (115).

13. A method (300) for supplying liquefied natural gas, called "LNG", characterized in that it comprises:

a step (305) for storing evaporation gas from a third-party device in an evaporation gas buffer tank comprising an inlet for evaporation gas adapted to receive evaporation gas from a third-party device ,

a stage (310) for transferring evaporation gas from the buffer tank to an LNG storage capacity,

downstream of the transfer step (310), a step of compression (330) of the evaporation gas,

a step (315) of heat exchange between the evaporation gas transferred and LNG transferred to a third device resulting from the LNG storage capacity for liquefying or cooling the evaporation gas,

a step (320) for storing LNG in the storage capacity,

a step (325) for transferring LNG from the storage capacity to a third-party device.