Plant and method for providing liquefied natural gas
阅读说明：本技术 用于提供液化天然气的设备和方法 (Plant and method for providing liquefied natural gas ) 是由 H·古达查 H·马吕士 Y·泽勒福 于 2018-11-22 设计创作，主要内容包括：一种提供液化天然气的设备(100),所述液化天然气被称为LNG,所述设备包括：-蒸发气体缓冲罐(105),包括适于从第三方设备接收蒸发气体的蒸发气体的入口(110)；-转移构件(115),用于将蒸发气体从缓冲罐转移到LNG存储容器(120)；-位于转移构件(120)的下游的压缩机(140),用于压缩蒸发气体；-蒸发气体转移管道(125),用于将蒸发气体从转移构件转移到存储容器；-LNG存储容器；-LNG转移管道(130),用于将LNG从存储容器转移到第三方设备；以及-热交换器(135),用于在通过蒸发气体转移管道的蒸发气体与通过LNG转移管道的LNG之间进行热交换,热交换器被构造为液化或冷却蒸发气体。(Plant (100) for providing liquefied natural gas, referred to as LNG, comprising: -a boil-off gas buffer tank (105) comprising an inlet (110) adapted to receive boil-off gas of the boil-off gas from the third party device; -transfer means (115) for transferring boil-off gas from the buffer tank to the LNG storage vessel (120); -a compressor (140) downstream of the transfer member (120) for compressing the boil-off gas; -a boil-off gas transfer conduit (125) for transferring boil-off gas from the transfer member to the storage container; -an LNG storage vessel; -an LNG transfer conduit (130) for transferring LNG from the storage vessel to a third party facility; and-a heat exchanger (135) for exchanging heat between the boil-off gas passing through the boil-off gas transfer conduit and the LNG passing through the LNG transfer conduit, the heat exchanger being configured to liquefy or cool the boil-off gas.)
1. A plant (100, 200) for providing liquefied natural gas, referred to as LNG, characterized by comprising:
-a boil-off gas buffer tank (105) comprising an inlet (110) adapted to receive boil-off gas of the boil-off gas from the third party device;
-transfer means (120) for transferring the boil-off gas from the buffer tank to an LNG storage vessel (115);
-a compressor (140) downstream of the transfer member (120) for compressing the boil-off gas;
-a boil-off gas transfer duct (125) for transferring the boil-off gas from the transfer member to the storage container;
-the LNG storage vessel;
-an LNG transfer conduit (130) for transferring LNG from the storage vessel to a third party facility; and
-a heat exchanger (135) for exchanging heat between boil-off gas passing through the boil-off gas transfer conduit and LNG passing through the LNG transfer conduit, the heat exchanger being configured to liquefy or cool the boil-off gas.
2. The device (100, 200) according to claim 1, wherein the transfer member (120) is a valve or a drain device controlled according to a pressure value inside the buffer tank (105) measured by a pressure sensor (145).
3. The plant (100, 200) according to claim 1 or 2, wherein the boil-off gas and the LNG circulate in opposite directions within the heat exchanger (135).
4. The apparatus (100, 200) according to any of claims 1 to 3, wherein the working pressure value of the buffer tank (105) is at least 2 bar greater than the working pressure value of the storage vessel (115).
5. The apparatus (100, 200) according to any of claims 1 to 4, comprising a bypass (150) of a transfer duct (125) for liquefied or cooled boil-off gas in the heat exchanger (135) downstream of the heat exchanger, the supply of boil-off gas to the bypass being controlled in dependence on the temperature measured from the boil-off gas at the outlet of the heat exchanger by a temperature sensor (155).
6. The apparatus (100, 200) of claim 5, comprising a first valve (160) on the bypass (150) and a second valve (165) on the boil-off gas transfer conduit (125) downstream of the bypass, the opening of the first or second valve being controlled in dependence on the measured boil-off gas temperature.
7. The plant (100, 200) according to any of claims 1 to 6, comprising means (170) for transferring liquefied boil-off gas from the buffer tank (105) to the LNG transfer pipeline (130).
8. The apparatus (200) according to any one of claims 1 to 7, comprising:
-an extraction line (205) for extracting boil-off gas within the storage vessel (115);
-a compressor (210) for compressing boil-off gas passing through the extraction line; and
-a supply line (215) for supplying compressed boil-off gas to the buffer tank (105).
9. The apparatus (200) of claim 8, wherein the boil-off gas compressor (210) comprises an inlet (110) for boil-off gas, the inlet (110) being adapted to receive the boil-off gas from a third party apparatus.
10. The apparatus (200) according to any one of claims 1 to 9, comprising means (126) for cooling the evaporation gas flow downstream of the transfer member (120).
11. The plant (200) according to claim 10, comprising a regulator (136) for the gas flow downstream of the heat exchanger (135), the regulator (136) being configured to expand the liquefied natural gas to a defined pressure.
12. The apparatus (200) according to claims 11 and 5, comprising a gas/liquid separator (137) downstream of the regulator (136), the gaseous boil-off gas being supplied to the bypass (150) and the liquid boil-off gas being supplied to the storage vessel (115).
13. A method (300) for providing liquefied natural gas, referred to as LNG, characterized by comprising:
-a step (305) of storing boil-off gas from a third party device in a boil-off gas buffer tank comprising an inlet adapted to receive boil-off gas of the boil-off gas from the third party device;
-a step (310) of transferring boil-off gas from the buffer tank to an LNG storage vessel;
-a compression step (330) for compressing the boil-off gas, located downstream of the transfer step (310);
-a step (315) of heat exchanging between the transferred boil-off gas and the LNG transferred from the LNG storage vessel to the third party device to liquefy or cool the boil-off gas;
-a step (320) of storing LNG in the storage vessel;
-a step (325) of transferring LNG from the storage vessel to a third party facility.
Technical Field
The present invention relates to an apparatus and method for providing liquefied natural gas. It finds particular application in the field of LNG supply for land and ocean-going vessels.
Background
The environmental and economic advantages of liquefied natural gas (hereinafter "LNG"), as compared to other fossil fuels, have driven the rapid expansion of LNG for use as a road or marine fuel.
In general, an LNG service station is composed of an LNG receiving system, a cryogenic storage device that allows LNG to be stored in a supercooled state at an operating pressure of 7 to 9 bar, a cryogenic pump that can transfer LNG, and a distribution system that refuels vehicles.
Today, three types of vehicles may be fueled using LNG:
the first type is fuelled with cold LNG at a pressure of 3 bar;
the second type is fuelled with saturated LNG at a pressure of 8 bar; and
the third category is fuelled with super saturated LNG at a pressure of 18 bar.
Currently, the pressure of most vehicles is 8 bar. At 8 bar and 18 bar vehicle fueling, LNG vaporizes to a relatively high degree, producing BOG (boil off gas). The size of the vehicle gas tank may withstand the pressure increase, but the design of the device is still limited by the maximum allowable pressure.
Therefore, to prevent the maximum pressure from being reached, there is a return of gas from the vehicle to the filling station, which results in a release of a large amount of gas into the atmosphere.
The gas returned to the LNG storage is the heat source for the LNG, thereby promoting vaporization of the LNG and thus increasing the pressure in the storage. These vaporizations or BOG must be controlled without release to the atmosphere.
This increases the operational complexity of the station, as does product loss.
Further, LNG stored in the storage tank of the service station is generally in a supercooled state. The heat sources that allow LNG saturation (8 bar and 18 bar) come from the open air, thus requiring the installation of a large number of heat exchanger surfaces at the site.
In addition, there are two methods of providing LNG fuel for 8 bar and 18 bar vehicles:
-bulk saturation process comprising storage of LNG in saturated state;
-a method comprising using an "in flight LNG saturation" module designed to provide LNG in a saturated state from subcooled LNG.
For compressed lng (clng) service stations, it is known to store the returned gas in a buffer tank for CNG. Some LNG plants accept returned natural gas without concern for its effect on BOG production. These stations are typically equipped with BOG liquefaction systems.
Current solutions use air vaporizers to obtain saturated LNG, which requires very large exchange surfaces and large occupied space.
The "saturation in flight" system has the disadvantage of requiring very efficient but expensive exchangers and of requiring very complex control systems, which present problems of operational stability.
Finally, the bulk saturation system does not provide fuel for vehicles operating at 3 bar pressure and reduces storage capacity and storage time.
It should be noted that for stations equipped with BOG liquefaction systems, these systems are expensive and have no potential return on investment.
Disclosure of Invention
The present invention aims to remedy all or part of these drawbacks.
To this end, according to a first aspect, the present invention envisages a plant for providing liquefied natural gas (referred to as LNG) comprising:
-a buffer tank for boil-off gas comprising an inlet for receiving boil-off gas of the boil-off gas from a third party device;
-transfer means for transferring boil-off gas from the buffer tank to the LNG storage vessel;
-a compressor downstream of the transfer member for compressing the boil-off gas;
-a boil-off gas transfer conduit for transferring boil-off gas from the transfer member to the storage container;
-an LNG storage vessel;
-an LNG transfer conduit for transferring LNG from the storage vessel to a third party facility; and
-a heat exchanger for heat exchange between boil-off gas passing through the boil-off gas transfer conduit and LNG passing through the LNG transfer conduit, the heat exchanger being configured to liquefy or cool the boil-off gas.
Due to these arrangements, boil-off gas transferred from the buffer tank to the storage vessel is liquefied, which enables LNG stored in the vessel to be maintained at a low temperature, thereby reducing the formation of BOG in the vessel.
These arrangements also improve the performance of the apparatus in terms of liquefaction of boil-off gas.
In some embodiments, the transfer member is a valve or drain that is controlled according to the value of the pressure within the buffer tank measured by the pressure sensor.
In some embodiments, the boil-off gas and the LNG circulate in opposite directions within the heat exchanger.
These embodiments improve the performance of the apparatus in terms of liquefaction of boil-off gas.
In some embodiments, the buffer tank has an operating pressure value that is at least 2 bar greater than the operating pressure value of the storage vessel.
These embodiments allow the boil-off gas to flow naturally from the buffer tank to the storage container.
In some embodiments, the plant that is the subject of the invention comprises a bypass of the transfer conduit for the liquefied or cooled boil-off gas in the heat exchanger, downstream of the heat exchanger, the supply of boil-off gas to the bypass being controlled as a function of the temperature measured by the temperature sensor for the boil-off gas at the outlet from the heat exchanger.
These embodiments allow recirculation of boil-off gas that has not yet reached a defined temperature value.
In some embodiments, the apparatus according to the inventive subject matter includes a first valve on the bypass and a second valve on the boil-off gas transfer conduit downstream of the bypass, the opening of the first valve or the second valve being controlled in dependence on the measured boil-off gas temperature.
These embodiments allow recirculation of boil-off gas that has not yet reached a defined temperature value.
In some embodiments, a plant according to the inventive subject matter includes means for transferring liquefied boil-off gas from a buffer tank to an LNG transfer pipeline.
These embodiments enable the saturation of LNG transferred to third party equipment.
In some embodiments, an apparatus according to the inventive subject matter includes:
-an extraction line for extracting boil-off gas from the storage vessel;
-a compressor for compressing the boil-off gas through the extraction line; and
-a supply line for supplying compressed boil-off gas to the buffer tank.
These embodiments allow the storage volume required for the buffer tank to be minimized.
In some embodiments, the boil-off gas compressor comprises an inlet for boil-off gas, the inlet being adapted to receive boil-off gas from a third party device.
In some embodiments, an apparatus according to the inventive subject matter includes a means for cooling the evaporative airflow downstream of the transfer member.
These embodiments make it possible to partially or completely cool or liquefy the boil-off gas stream exiting the heat exchanger.
In some embodiments, a plant according to the inventive subject matter includes a regulator for a gas stream downstream of the heat exchanger, the regulator configured to expand liquefied natural gas to a defined pressure.
In some embodiments, an apparatus according to the inventive subject matter includes a gas/liquid separator downstream of the regulator, the gaseous boil-off gas being supplied to the bypass and the liquid boil-off gas being supplied to the storage vessel.
According to a second aspect of the invention, the invention envisages a method of providing liquefied natural gas, referred to as LNG, comprising:
-a step of storing the boil-off gas from the third party device in a boil-off gas buffer tank, the boil-off gas buffer tank comprising an inlet adapted to receive boil-off gas from the third party device;
-a step of transferring boil-off gas from the buffer tank to the LNG storage vessel;
-a compression step, downstream of the transfer step, for compressing the evaporation gas;
-a step of heat exchange between the transferred boil-off gas and the LNG transferred from the LNG storage vessel to the third party device to liquefy or cool the boil-off gas;
-a step of storing LNG in a storage vessel;
-a step of transferring LNG from the storage vessel to a third party facility.
Since certain objects, advantages and features of the method, which is the subject of the present invention, are similar to those of the device, which is the subject of the present invention, further description is omitted here.
Drawings
Further advantages, objects and particular features of the invention will become apparent from the following non-limiting description of at least one particular embodiment of the apparatus and method which are the subject of the invention, with reference to the accompanying drawings included in the appendix, in which:
figure 1 schematically shows a first particular embodiment of the device that is the subject of the present invention;
figure 2 schematically shows, in the form of a logic diagram, a series of specific steps of the method that is the subject of the invention; and
figure 3 schematically shows a second particular embodiment of the device that is the subject of the invention.
Detailed Description
The present description is given in a non-limiting manner, and each feature of an embodiment can be combined in an advantageous manner with any other feature of any other embodiment.
Note that the drawings are not to scale.
Subsequently, "third party equipment" refers to any equipment that uses LNG to generate energy. Such third-party devices are for example land, sea, river or air vehicles.
In fig. 1, which is not drawn to scale, a schematic diagram of an embodiment of a device 100 which is the subject of the present invention is shown. The plant 100 for providing liquefied natural gas (referred to as LNG) comprises:
a boil-off
a transfer means 120 for transferring boil-off gas from the buffer tank to the
a boil-off
-an LNG storage vessel;
an LNG transfer conduit 130 for transferring LNG from the storage vessel to a third party facility; and
a
The
The
The
Boil-off gas is supplied to the
The
The choice of this setpoint value is arbitrary and is set by the operator. Depending on the design and cost goals of the site. For example, if the station is sized to supply a vehicle operating at 18 bar, a set pressure of 15 or 16 bar may be used.
A
Such a
Upon exiting the
The evaporation gas, which is compressed or not compressed by the
The
The
Preferably, the LNG and boil-off gas are circulated in opposite directions to optimise heat exchange between the two fluids.
For example, the
The
Preferably, the operating pressure in the
The
The transfer tubing 130 is connected to a connector, the kind of which depends on the type of third party device connected to the device 100.
In some variations, the plant 100 includes a
In some preferred embodiments, such as shown in fig. 1, the apparatus 100 comprises a
In some preferred embodiments, as shown in FIG. 1, the apparatus 100 includes a
When the temperature of the boil-off gas is below the predetermined threshold temperature, the
In some preferred embodiments, as shown in fig. 1, the plant 100 comprises
Fig. 3 shows a schematic diagram of an embodiment of a
a boil-off
a transfer means 115 for transferring boil-off gas from the buffer tank to the
a
a boil-off
-an LNG storage vessel;
an LNG transfer conduit 130 for transferring LNG from the storage vessel to a third party facility; and
a
The
The
The
The
Boil-off gas is supplied to the
The
For example, the setpoint value is selected to correspond to a maximum operating pressure of the
A
At the exit from the
The evaporation gas, which is compressed or not compressed by the
In some embodiments, as shown in fig. 3, the
In some embodiments, as shown in FIG. 3, the
In some embodiments, as shown in FIG. 3, the
The separator 137 is, for example, a separator drum.
The
The
Preferably, the LNG and boil-off gas are circulated in opposite directions to optimise heat exchange between the two fluids.
For example, the
For example, the
Preferably, the operating pressure in the
The
The transfer tubing 130 is connected to a connector, the kind of which depends on the type of third party device connected to the
In some variations, the
In some preferred embodiments, as shown in fig. 3, the
In some preferred embodiments, as shown in FIG. 3, the
When the temperature of the boil-off gas is below the predetermined threshold temperature, the
In some preferred embodiments, as shown in fig. 3, the
The
In some preferred embodiments, as shown in FIG. 3, the
an
a
a
The
The
In some preferred embodiments, as shown in FIG. 3, the boil-off
Fig. 2 schematically shows a particular embodiment of a
-a
-a
a
-a
-a
a
As described with reference to fig. 1 and 3, by utilizing the
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