KR101966200B1 - System and Process for Liquefied Gas Filling - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquefied gas supply system and method for supplying liquefied gas from a liquefied gas storage tank for storing liquefied gas to a customer, and more particularly to a liquefied gas supply system for supplying liquefied gas to a customer where intermittent supply of liquefied gas occurs The present invention relates to a liquefied gas supply system and method capable of efficiently treating an evaporated gas and a residual liquefied gas generated on a liquefied gas supply pipe.
A liquefied gas supply system according to the present invention comprises: a liquefied gas supply line through which liquefied gas discharged from a liquefied gas storage tank flows to a liquefied gas consumer; And a residual liquefied gas recovery line branched from the liquefied gas supply line and connected to the liquefied gas storage tank, for providing a flow path so that liquefied gas remaining in the liquefied gas supply line is recovered to the liquefied gas storage tank , The residual liquefied gas recovery line is connected from the lowest position of the liquefied gas supply line to the top of the liquefied gas storage tank and the residual liquefied gas is supplied to the residual liquefied gas recovery line when the liquefied gas supply line is closed And is recovered in a liquid state by the vapor pressure.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquefied gas supply system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquefied gas supply system and method for supplying liquefied gas from a liquefied gas storage tank for storing a liquefied gas to a customer, and more particularly to a liquefied gas supply system for supplying liquefied gas to a customer where intermittent supply of liquefied gas occurs The present invention relates to a liquefied gas supply system and method capable of effectively treating an evaporated gas and a residual liquefied gas generated on a liquefied gas supply line.

Liquefied gas is a liquid that has been compressed and cooled in a gaseous state under normal temperature and normal pressure conditions. When it is in a liquid state, its volume is considerably reduced, which makes it easier to transport distant. Liquefied natural gas (LNG), for example, is a liquefied natural gas. Its volume is reduced to about 1/600 when it is in a liquid state than it is in a gaseous state. It is therefore common for natural gas to be transported and stored in LNG.

Such liquefied gas, particularly LNG, has been rapidly increasing in demand worldwide in recent years. Since LNG is an eco-friendly fuel with little air pollutants emitted during combustion, it is attracting attention in various fields such as automobiles and ships. If LNG is used as the main fuel, it is expected to be an effective countermeasure for solving environmental pollution problems such as carbon emissions and fine dusts.

The demand for LNG fuel vehicles and LNG fuel vessels, which use LNG as fuel, is intermittent. In order to universally and continuously operate a vehicle using LNG as a fuel, an LNG refueling station is provided at a specific position, such as a system using fuel oil such as conventional diesel oil as a main fuel, When the charge demand occurs, it can be moved to the LNG charging station to charge the LNG. These LNG filling stations are equipped with LNG storage tanks, LNG supply facilities, and dispensers.

LNG storage tanks are fixedly installed in a conventional LNG charging station, and the LNG stored in the LNG storage tank is gradually exhausted while operating the LNG charging station. In order to fill the exhausted LNG, LNG is filled in the LNG feeder, for example, at the LNG loading station in the LNG terminal by using a tanker or the like, and the LNG carried by the LNG filling station is installed in the LNG filling station using the tank lorry And filling with a fixed LNG storage tank.

LNG is a liquefied gas at a cryogenic temperature of about -163 ° C at 1 atmospheric pressure, so the LNG storage tank is generally heat-treated. However, even if the LNG storage tank is insulated, the LNG continuously vaporizes in the LNG storage tank due to heat invaded from the outside, thereby generating boil off gas (BOG). Evaporation gas causes the internal pressure of the LNG storage tank to increase. If the pressure of the LNG storage tank continuously increases, the explosion gas may cause a dangerous situation. Therefore, if the internal pressure of the LNG storage tank rises above the set pressure, the safety valve must be opened to vent the evaporative gas.

Evaporation gas may be generated by natural vaporization of LNG stored in LNG storage tank, but it may be generated by pressure difference or heat transfer when LNG is supplied to LNG storage tank, and LNG remaining in piping after heat- And the like. The evaporated gas generated in the pipe also causes the pressure rise of the pipe and must be discharged to the outside. However, since the evaporation gas generated by LNG vaporization is mainly composed of methane (CH ₄ ), which has the highest liquefaction point, discharging the evaporation gas to the atmosphere is a waste of LNG and there is also concern about environmental pollution. Therefore, it is most appropriate to collect the evaporated gas generated in the piping back to the LNG storage tank.

However, when the evaporation gas generated from the piping is recovered to the LNG storage tank, the pressure of the LNG storage tank becomes higher due to the evaporation gas spontaneously vaporized in the LNG storage tank as well as the evaporated gas recovered to the LNG storage tank. If the pressure increase rate of the LNG storage tank is rapidly increased, not only the safety risk but also the amount of the evaporated gas discharged through the safety valve opening is increased, so that the LNG storage tank is safely operated and discharged to the outside. Efforts are needed to reduce the amount of evaporative gas.

Accordingly, it is an object of the present invention to solve the above-mentioned problems, and it is an object of the present invention to provide a liquefied gas storage tank which is capable of effectively recovering evaporative gas generated in a liquefied gas supply line, And to provide a liquefied gas supply system and method that can reduce the amount of wasted evaporation gas by reducing the rate of pressure increase.

According to an aspect of the present invention, there is provided a liquefied gas supply line in which a liquefied gas discharged from a liquefied gas storage tank flows to a liquefied gas consumer; And a residual liquefied gas recovery line branched from the liquefied gas supply line and connected to the liquefied gas storage tank, for providing a flow path so that liquefied gas remaining in the liquefied gas supply line is recovered to the liquefied gas storage tank , The residual liquefied gas recovery line is connected from the lowest position of the liquefied gas supply line to the top of the liquefied gas storage tank and the residual liquefied gas is supplied to the residual liquefied gas recovery line And is recovered in a liquid state by vapor pressure along the line.

Preferably, the recovery line is connected to the liquefied gas storage tank so that the evaporated gas generated in the liquefied gas supply line is recovered to the liquefied gas storage tank; And a cooler provided in the recovery line and cooling the evaporated gas recovered in the liquefied gas storage tank.

Preferably, the apparatus further includes a flow path switching means provided in the liquefied gas supply line and switching the direction of the flow path or opening / closing the flow path, wherein the flow path switching means is selectively opened and closed to close the liquefied gas supply line, It is possible to control the flow path so that the liquefied gas flowing through the gas supply line is supplied to the liquefied gas consumer or is recovered to the liquefied gas storage tank.

Preferably, the gas-liquid separator is provided in the liquefied gas supply line and performs gas-liquid separation of the fluid flowing through the liquefied gas supply line. And a second evaporative gas recovery line connected to the recovery line from the gas-liquid separator and adapted to recover evaporated gas separated from the gas-liquid separator to the liquefied gas storage tank.

And an ejector connected to the second evaporative gas recovery line and sucking the evaporated gas separated by the gas-liquid separator, wherein the ejector is provided in the liquefied gas supply line and is recovered to the liquefied gas storage tank The evaporation gas can be sucked by the negative pressure formed by the liquefied gas.

The liquefied gas consumer may be a liquefied gas-fueled vehicle or a liquefied gas-fueled vehicle in which demand is intermittently generated, or a liquefied gas-fueled vehicle It may be a liquefied gas fuel vessel.

According to another aspect of the present invention, there is provided a liquefied gas supply system for supplying a liquefied gas from a liquefied gas storage tank to a liquefied gas consumer using a liquefied gas supply line, And the residual liquefied gas remaining in the liquefied gas supply line until the liquefied gas supply line is opened is supplied to the liquefied gas storage tank through the residual liquefied gas supply line branched from the liquefied gas supply line by the vapor pressure Wherein the liquefied gas is recovered from the liquefied gas.

Preferably, before supplying the liquefied gas to the liquefied gas consumer, the liquefied gas may be discharged from the liquefied gas storage tank to cool down the liquefied gas supply line, cool down the liquefied gas supply line, The liquefied gas recovered to the liquefied gas storage tank can be recovered by cooling in the cooler.

Preferably, the evaporation gas generated during the cooling-down of the liquefied gas supply line is separated from the gas-liquid separator provided in the liquefied gas supply line, and the liquefied gas recovered in the liquefied gas storage tank passes through the ejector And then cooled in the cooler and recovered to the liquefied gas storage tank.

Preferably, when the liquefied gas is supplied to the liquefied gas consumer, the liquefied gas supply line is connected to the liquefied gas consumer side. When the liquefied gas supply line is cooled down, the liquefied gas supply line is connected to the liquefied gas storage tank To be connected to each other.

Preferably, the liquefied gas consumer may be a liquefied gas fuel vehicle or a liquefied gas fuel vessel in which demand is intermittently generated.

The liquefied gas supply system and method according to the present invention can efficiently supply liquefied gas to a liquefied gas consumer where intermittent liquefied gas demand occurs such as an LNG fuel vehicle and can reduce the amount of evaporated gas that is discarded It is environmentally friendly and economical.

Further, it is possible to effectively recover the evaporated gas generated in the liquefied gas supply line, and in particular, to efficiently recover a large amount of the generated evaporative gas in the cool-down state.

Further, since the vaporized gas in the gaseous state is recovered in the liquefied gas supplied to the liquefied gas consumer, only the liquefied gas in the liquid state is supplied to the liquefied gas consumer, which is highly reliable and economical. Particularly, when the liquefied gas is supplied to the liquefied gas consumer after cooling down the liquefied gas supply line, the evaporated gas generated further is effectively separated by the gas-liquid separator, and the liquefied gas can be efficiently supplied to the customer.

Further, the evaporated gas separated from the gas-liquid separator can be sucked and recovered by the negative pressure formed by the liquefied gas recovered in the liquefied gas storage tank by using the ejector, thereby effectively sucking the evaporated gas.

In addition, it is possible to minimize the rate of pressure increase of the liquefied gas storage tank by cooling and recovering the evaporated gas recovered to the liquefied gas storage tank. Therefore, it is possible to safely operate the storage tank and to discharge the amount of evaporated gas, Can be reduced.

The liquefied gas supply system and method according to the present invention is a system for supplying a liquefied gas to a liquefied gas consumer and then supplying the liquefied gas remaining on the liquefied gas supply line to a liquid state until a next demand occurs, It is possible to reduce the amount of evaporation gas generated.

1 is a view showing a liquefied gas supply system according to an embodiment of the present invention, showing a state in which liquefied gas is supplied to a customer.
Fig. 2 is a view showing a liquefied gas supply system according to an embodiment of the present invention, in which the liquefied gas supply line is cooled down. Fig.
3 is a view showing a liquefied gas supply system according to an embodiment of the present invention, showing a state in which residual liquefied gas is recovered.

In order to fully understand the operational advantages of the present invention and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings, which illustrate preferred embodiments of the present invention, and to the contents of the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout. The same elements are denoted by the same reference numerals even though they are shown in different drawings.

Hereinafter, a liquefied gas supply system and method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG.

In the following embodiments, LNG (Liquefied Natural Gas) as a liquefied gas will be exemplified. Liquefied gas storage tanks are LNG storage tanks for storing LNG. Liquefied gas users are liquefied gas fuel vehicles, particularly LNG The present invention can be applied to various liquefied gases, and the following embodiments can be modified into various other forms, and the scope of the present invention is not limited thereto. It is not limited to the example.

The liquefied gas supply system (C) according to an embodiment of the present invention includes an LNG storage tank (T) for storing LNG, as shown in Figs. 1 to 3; And an LNG supply line LL connecting the LNG storage tank T and the LNG demanding site V that requires LNG stored in the LNG storage tank T. The LNG supply line LL, Flows along the LNG supply line LL.

In this embodiment, the LNG storage tank T may be a standardized International Organization for Standardization (ISO) LNG tank container T. When the LNG tank container T is completely filled with the LNG tank container T, the connection (coupling) with the LNG supply line LL is released, and the LNG tank container T and the LNG supply line LL, Can be reconnected.

That is, the empty LNG tank container T disconnected from the LNG supply line LL can be replaced with a new LNG tank container T filled with the LNG.

Therefore, according to the present embodiment, since the conventional LNG storage tank is fixedly provided, the process of filling LNG in the LNG storage tank T at the site where the liquefied gas supply system according to the present embodiment is applied is omitted, The amount of LNG that is lost due to the generation of a large amount of evaporative gas or flash gas in the process can be remarkably reduced. Further, it is possible to prevent the pressure of the LNG storage tank from rising sharply.

The LNG tank container (T) in which the LNG has been exhausted can be recovered to the LNG supplier, for example, the LNG carrier or the LNG terminal.

Herein, the LNG tank container T in which the stored LNG has been exhausted is referred to as an LNG tank container L in which the LNG is stored at a predetermined minimum liquid level in order to stably operate the LNG tank container T T), or may refer to an LNG tank container (T) at the time of replacement.

In this specification, the LNG tank container T filled with LNG refers to an LNG tank container in which the LNG tank container T having a predetermined minimum to maximum water level is stored in order to stably operate the LNG tank container T. [ May mean an LNG tank container (T) or a LNG tank container (T) having a highest level of LNG stored therein, and may be an LNG tank container (T) at a time when it is ready to be connected to the LNG supply line (LL).

In this embodiment, the operation pressure of the LNG storage tank T may be about 4 to 6 bar, and if it exceeds 6 bar, the safety valve may be opened to discharge the evaporation gas.

Further, the LNG storage tank T may be heat-treated.

The liquefied gas supply system C according to the present embodiment may further include an LNG pump 10 provided in the LNG supply line LL and discharging the LNG from the LNG storage tank T. [ The LNG pump 10 may be provided in the pump case, and the pump case may be operated such that the LNG is maintained at a predetermined level or more. That is, the LNG is filled into the pump case from the LNG storage tank T, and the LNG filled in the pump case can be sucked into the LNG supply line LL to be discharged to the LNG consumer V through the LNG supply line LL.

Hereinafter, the pump case having the LNG pump and the LNG pump built in the pump case will be referred to as an 'LNG pump' as one member, and when it is necessary to refer to the pump case and the LNG pump respectively, .

In this embodiment, the discharge pressure of the LNG pump 10 can be a maximum design pressure of about 12 to 14 bar and an operating pressure of about 6 to 7 bar.

According to the present embodiment, the first evaporative gas recovery line LNG connected to the LNG storage tank T from the LNG pump 10 and recovering the evaporated gas discharged from the LNG pump 10 to the LNG storage tank T (BL1).

The LNG filled in the pump case can be vaporized by the heat entering from the outside and the heat generated by the operation of the LNG pump 10. [ The evaporated gas discharged from the LNG pump 10 can be recovered to the LNG storage tank T through the first evaporated gas recovery line BL1.

The first evaporative gas recovery line BL1 may extend from the top of the LNG pump 10 to the top of the LNG storage tank T and may be provided to directly connect the LNG pump 10 and the LNG storage tank T And may be arranged to be merged from the upper portion of the LNG pump 10 to a recovery line DL described later, as shown in Figs.

The point at which the first evaporated gas recovery line BL1 is merged into the recovery line DL may be single after the cooler 60 described later or as connected to the front end of the cooler 60 as shown in FIGS. It is possible. The evaporated gas recovered from the LNG pump 10 is cooled in the cooler 60 and then supplied to the LNG storage tank T ).

The LNG supply line LL according to the present embodiment includes a period in which the LNG demand destination V can be connected to and disconnected from the LNG fuel vehicle at an end thereof when the LNG demand V is irregularly supplied with LNG such as an LNG fuel vehicle can do. Hereinafter, as shown in FIG. 1, a section where connection with and disengagement from the LNG fueling vehicle is possible will be referred to as an LNG filling line CL.

The LNG charging line CL may be provided as an arm or a flexible hose. The LNG filling line (CL) can be connected to the LNG demand destination (V) so as to be detachable.

The LNG filling line (CL) may be composed of a vacuum line to minimize the generation of evaporative gas during charging of the LNG, or it is preferably arranged to be vacuum insulated.

For example, if the LNG fuel vehicle V desires to receive LNG, the LNG filling line CL is connected to the LNG fueling vehicle V to supply the LNG to the LNG fueling vehicle V and the LNG fueling vehicle V The connection between the LNG filling line CL and the LNG fuel vehicle V can be released and the LNG fuel can be supplied to the another LNG fuel vehicle V in connection with the LNG filling vehicle CL.

In addition, the LNG demand source V capable of receiving the LNG from the liquefied gas supply system according to the present invention is an LNG-fueled vehicle, which is capable of receiving LNG irregularly due to intermittent demand for LNG, It may be an LNG fuel vessel. In this case, as described above, the LNG charging line (CL) is provided and the LNG supply line (LL) can be connected to and disconnected from the LNG demand destination (V).

On the other hand, LNG demand (V) may be that LNG supply lines (LL) such as factories, housing complexes, and buildings receive LNG regularly or continuously without being released from LNG demand (V). In this case, only the replacement of the LNG storage tank (T) can be performed while the LNG supply line (LL) maintains connection with the LNG demand destination (V). However, the maintenance may be temporarily released if necessary.

In the liquefied gas supply system according to the present invention, the LNG supply line LL is connected to the LNG storage tank T so that the LNG flowing through the LNG supply line LL is returned to the LNG storage tank T A recovery line DL to be provided can be further connected.

The recovery line DL can be communicated with or disconnected from the LNG supply line LL by the channel switching means 40 to be described later.

The recovery line DL includes a gaseous evaporation gas generated in a liquid LNG or LNG supply line LL which is recovered again from the LNG supply line LL to the LNG storage tank T, The resulting gas-liquid mixture may flow.

The liquefied gas supply system C according to the present embodiment further includes a flow path switching means 40 for opening and closing the LNG supply line LL or switching the flow path of the LNG flowing through the LNG supply line LL .

The flow path switching means 40 of the present embodiment may be provided as a valve and may be a three-way valve. That is, in the present embodiment, the flow path switching means 40 will be described as an example of the flow path switching valve 40 having three inlets. The three inlets are LNG supply line LL, And the LNG charging line CL are connected.

The LNG may flow from the LNG supply line LL to the LNG storage tank T through the recovery line DL and the LNG storage tank T through the LNG charge line CL, (V). Or the inlet of the flow path switching valve 40 may be closed to maintain the LNG supply line LL interval between the LNG storage tank T and the flow path switching valve 40 And may be recovered to the LNG storage tank T through a remaining LNG recovery line RL to be described later.

Alternatively, although not shown in the drawings, the flow path switching means 40 may be provided to be connected to a quick disconnect coupling connection of the LNG supply line LL, the recovery line DL and the LNG charging line CL . When the flow path switching means 40 is provided with a quick coupling connection, the flow path can be switched by replacing the connecting direction as necessary. The replacement of the connection direction can be controlled manually or automatically by a control unit (not shown).

1 to 3, the liquefied gas supply system C according to the present embodiment differs from the LNG storage tank T in which LNG branched from the LNG supply line LL and remaining in the LNG supply line LL is stored in the LNG storage tank T And a residual LNG recovery line RL connected to an upper portion of the LNG storage tank T so as to be recovered in the LNG storage tank T.

The residual LNG recovery line RL may be branched from the lowest position of the LNG supply line LL, for example, from the lowermost portion of the U-shaped pipe of the LNG supply line LL, as shown in Fig.

More specifically, the remaining LNG recovery line RL can be branched from the lowermost portion of the hermetic section.

3, when all of the openings of the flow path switching valve 40 are closed or at least the inlet connected to the LNG supply line LL and the inlet connected to the LNG filling line CL are closed, as described above, A sealed section in which a certain section between the LNG storage tank T and the passage switching valve 40 is sealed is formed.

The sealing section may be between the LNG storage tank T and the flow path switching valve 40 or between the LNG pump 10 and the flow path switching valve 40. The gas- (40).

In this embodiment, when the hermetic section is formed, the LNG remains in the hermetic section.

The LNG supply line LL and the LNG charging line CL are disconnected by controlling the flow path switching valve 40 after the LNG is supplied to the LNG demanding place V, Occurs during a periodic or irregular period of time until the engine 40 is opened to the collection line DL or the LNG charging line CL side.

For example, when the flow path switching valve 40 is opened, the flow path switching valve 40 is controlled to be opened toward the LNG filling line CL in order to supply the LNG to the next LNG demand destination V, LL) to be opened to the recovery line (DL) side in order to cool down.

As described above, when the flow path switching valve 40 is opened in one direction, the sealing section disappears.

 When the LNG remains in the closed section, the temperature of the LNG remaining in the closed section is increased by the heat penetrated from the outside until the closed section disappears and gradually vaporized. If the residual LNG is vaporized in the closed section, the pressure of the LNG supply line (LL) is increased. If the evaporation gas is not discharged, it may cause a dangerous situation such as damaging the piping, and the residual LNG needs to be treated.

When the residual LNG is vaporized, the pressure in the closed zone may rise up to about 10 bar to 14 bar. If the pressure of the residual LNG rises to a value higher than the above pressure, a safety accident may occur. For example, it can be around 25 minutes or so. That is, if new LNG demand does not occur within 25 minutes, the evaporated gas vaporized from the residual LNG must be released to the atmosphere. However, the maximum pressure to withstand the sealed zone and the time to reach the maximum pressure may differ depending on the thickness, diameter, and length of the LNG supply line (LL) pipe.

However, according to the present embodiment, the residual LNG can be recovered to the LNG storage tank T in a liquid state by providing the remaining LNG recovery line RL connected to the LNG storage tank T from the closed section.

As described above, the operating pressure of the LNG storage tank T of the present embodiment is about 4 bar to 6 bar and the pressure of the sealed section is stored in the LNG storage tank When the internal pressure of the tank T is higher than the internal pressure of the tank T, the residual LNG is recovered to the LNG storage tank T. At this time, the pressure rising rate of the sealed section is higher than the pressure rising rate of the LNG storage tank T, and the residual LNG is recovered to the LNG storage tank T in a liquid state by the pressure difference.

Therefore, according to the present embodiment, since the residual LNG is recovered to the LNG storage tank T in a liquid state by its own vapor pressure without any additional power, no additional energy is required, and heat invasion by driving the power source You do not have to worry.

That is, the residual LNG is vaporized in the closed section and a pressure difference with the LNG storage tank T is generated by its own pressure, and is recovered to the LNG storage tank T by the pressure difference.

The residual LNG recovery line RL of this embodiment may be provided with a micro tube whose diameter is smaller than that of the LNG supply line LL.

The liquefied gas supply system C according to the present embodiment further includes a gas-liquid separator 20 provided in the LNG supply line LL and separating the evaporated gas from the LNG flowing along the LNG supply line LL can do.

The LNG flowing in the LNG feed line (LL) can be vaporized by external heat, so that a part of the LNG can flow into the vaporized vapor-liquid mixture state. That is, according to the present embodiment, by providing the gas-liquid separator 20, it is possible to separate the vaporized gas contained in the LNG supplied to the LNG demand destination V through the LNG supply line LL, (V).

The liquefied gas supply system C according to the present embodiment may further include a flow meter 30 for measuring the flow rate of LNG supplied to the LNG demand destination V through the LNG supply line LL. The flow meter 30 may be provided at the downstream end of the gas-liquid separator 20 between the point where the LNG charging line CL is connected from the LNG supply line LL and the gas-liquid separator 20.

For example, when the LNG consumer (V) is an LNG fuel vehicle (V) fueled by LNG, if the vapor-liquid mixed gas mixture is incorporated into the fuel storage tank of the LNG fuel vehicle (V) The internal pressure is increased and the flow rate of the fuel measured by the flow meter 30 becomes an amount including the evaporated gas so that the amount of effective LNG that can be used as actual fuel is less than the amount measured by the flow meter 30,

According to the present embodiment, however, only the liquid LNG can be supplied to the LNG consumer V by separating the evaporation gas from the gas-liquid separator 20, and since the flow meter 30 can measure only the flow rate of the effective liquid, Reliability can be ensured, and it is economical.

The gas-liquid separator 20 of the present embodiment is provided with a second evaporative gas recovery line BL2 for providing a flow path for discharging evaporated gas separated from the gas-liquid separator 20 from the gas-liquid separator 20 Can be connected.

The second evaporative gas recovery line BL2 is connected to the LNG storage tank T from the upper part of the gas-liquid separator 20 and is arranged to be joined to the recovery line DL as shown in FIGS. Or may be provided to be directly connected to the LNG storage tank T.

The evaporated gas combined into the recovery line DL through the second evaporated gas recovery line BL is supplied to the second evaporated gas recovery line BL by a control operation of a separate on-off valve (not shown) Can be sucked into the recovery line (DL) by the operation of the ejector (50).

The liquefied gas supply system C according to the present embodiment is provided with the LNG provided in the recovery line DL and recovered to the LNG storage tank T through the recovery line DL and the cooler 60 ).

It is preferable that the second evaporative gas recovery line BL2 through which the evaporated gas separated from the gas-liquid separator 20 flows is merged into the recovery line DL at the front end of the cooler 60. [

That is, the evaporated gas recovered to the LNG storage tank T along the second evaporative gas recovery line BL2 is cooled in the cooler 60 and is recovered to the LNG storage tank T. The evaporated gas cooled in the cooler 60 is recovered to the LNG storage tank T, so that the pressure rising rate of the LNG storage tank T can be reduced.

The cooling source for cooling the evaporation gas or LNG in the cooler 60 may be liquefied nitrogen (LN ₂ ).

In the cooler 60, the evaporated gas is cooled, the entire amount can be recovered to the LNG storage tank T as a cooled gaseous state, and is recovered to the LNG storage tank T as a vapor-liquid mixture or a liquid part in which the liquid is partially liquefied by cooling .

The liquefied gas supply system C according to the present embodiment may further include an ejector 50 for sucking the evaporated gas separated by the gas-liquid separator 20.

The ejector 50 of this embodiment may be provided on the recovery line DL and the second evaporative gas recovery line BL2 may be connected to the ejector 50 provided on the recovery line DL.

1 to 3, the ejector 50 can suck the evaporation gas using a negative pressure generated when the LNG flowing along the recovery line DL passes through the ejector 50. [

The flow path of the LNG is switched by controlling the flow path switching valve 40 so that the LNG supply line LL and the LNG supplementary line CL, the LNG supply line LL and the recovery line DL Connected or disconnected. Hereinafter, the flow of the LNG and the evaporation gas in accordance with the flow path switching will be described with reference to Figs. 1 to 3, in which the liquefied gas supply system C is shown.

In the operation of the liquefied gas supply system C according to the present embodiment, it is preferable that the LNG supply line LL be maintained at a cryogenic temperature such that cryogenic LNG can flow stably. However, the LNG supply line LL may be warmed up by a number of factors, such as external intrusion heat or inerting for maintenance. If the LNG supply line LL is not cooled, a large amount of LNG is vaporized while flowing through the LNG supply line LL by the heat of the LNG supply line LL itself. To prevent this, A cool-down operation is required to cool the LNG supply line LL before supplying the LNG supply line LL.

In the present embodiment, when the LNG demanding party V is intermittently supplying demand like the LNG fueling vehicle, the temperature of the LNG supply line LL may rise in the standby state until the next demand occurs have.

2, before the LNG supply line LL is connected to the LNG filling line CL side when the next demand occurs, the flow path switching valve 40 is controlled to be connected to the collection line DL side , And the LNG supply line (LL) can be cooled down by flowing LNG.

The LNG whose temperature is raised while cooling down the LNG supply line LL is recovered to the LNG storage tank T through the recovery line DL. At this time, the recovered LNG is cooled in the cooler 60, and the cooled LNG in the cooler 60 is introduced into the LNG storage tank T.

The LNG and the evaporated gas whose temperature is increased while cooling down the LNG supply line LL are cooled in the cooler 60 and then recovered to the LNG storage tank T so that the pressure increase rate of the LNG storage tank T Can be prevented from rapidly increasing.

During the cool-down of the LNG supply line (LL), a large amount of evaporative gas is generated, and the evaporated gas can be separated in the gas-liquid separator (20). The evaporated gas separated in the gas-liquid separator 20 is sucked into the recovery line DL by the negative pressure formed while the LNG recovered to the LNG storage tank T passes through the ejector 50 along the recovery line DL .

When the cool-down of the LNG supply line LL is completed, as shown in FIG. 1, the LNG supply line LL is controlled to be connected to the LNG charge line CL, V). ≪ / RTI >

The control of the flow path switching valve 40 can be performed manually or automatically by a control unit (not shown).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. It is.

T: LNG storage tank
V: LNG demand source
LL: LNG supply line
CL: LNG replacement line
DL: return line
RL: Residual LNG recovery line
BL1, BL2: Evaporative gas recovery line
10: LNG pump
20: gas-liquid separator
30: Flowmeter
40: Flow path switching valve
50: Ejector
60: cooler

Claims (11)

A liquefied gas supply line through which the liquefied gas discharged from the liquefied gas storage tank flows to the liquefied gas consumer;
A residual liquefied gas recovery line that branches from the liquefied gas supply line and is connected to the liquefied gas storage tank and provides a flow path so that liquefied gas remaining in the liquefied gas supply line is recovered to the liquefied gas storage tank;
A recovery line connected to the liquefied gas storage tank so that the evaporated gas generated in the liquefied gas supply line is recovered to the liquefied gas storage tank;
A gas-liquid separator provided in the liquefied gas supply line for separating the liquid flowing through the liquefied gas supply line by gas-liquid separation; And
And a second evaporative gas recovery line connected to the recovery line from the gas-liquid separator and adapted to recover evaporated gas separated from the gas-liquid separator to the liquefied gas storage tank,
The residual liquefied gas recovery line is connected from the lowest position of the liquefied gas supply line to the upper portion of the liquefied gas storage tank,
Wherein the residual liquefied gas is recovered in a liquid state by vapor pressure along the residual liquefied gas recovery line when the liquefied gas supply line is closed. The method according to claim 1,
And a cooler provided in the recovery line for cooling the evaporated gas recovered in the liquefied gas storage tank. The method of claim 2,
And a flow path switching means provided in the liquefied gas supply line for switching the direction of the flow path or opening / closing the flow path,
Wherein the flow path switching means selectively opens and closes to close the liquefied gas supply line or controls the flow path so that the liquefied gas flowing through the liquefied gas supply line is supplied to the liquefied gas consumer or is returned to the liquefied gas storage tank, . delete The method according to claim 1,
And an ejector connected to the second evaporative gas recovery line and sucking evaporative gas separated from the gas-liquid separator,
Wherein the ejector sucks the evaporation gas by a negative pressure which is provided in the liquefied gas supply line and is formed by the liquefied gas recovered in the liquefied gas storage tank. 4. The method according to any one of claims 1 to 3 and 5,
And a flowmeter provided in the liquefied gas supply line for measuring a flow rate of liquefied gas supplied to the liquefied gas consumer,
Wherein the liquefied gas consumer is a liquefied gas fuel vehicle or a liquefied gas fuel vessel in which demand is intermittently generated. The liquefied gas is supplied from the liquefied gas storage tank to the liquefied gas consumer via the liquefied gas supply line,
When the supply to the liquefied gas consumer is completed, the liquefied gas supply line is closed,
The residual liquefied gas remaining in the liquefied gas supply line until the liquefied gas supply line is opened is recovered to the liquefied gas storage tank through the residual liquefied gas supply line branched from the liquefied gas supply line by the vapor pressure,
Before supplying the liquefied gas to the liquefied gas consumer,
Discharging the liquefied gas from the liquefied gas storage tank to cool down the liquefied gas supply line,
Wherein the liquefied gas warm-up is recovered to the liquefied gas storage tank again while cooling-down the liquefied gas supply line. The method of claim 7,
Wherein the liquefied gas recovered to the liquefied gas storage tank is cooled by the cooler and recovered. The method of claim 8,
The evaporation gas generated during the cooling-down of the liquefied gas supply line is supplied to the evaporator
Liquid separator provided in the liquefied gas supply line,
Wherein the evaporation gas is sucked by using a negative pressure formed while the liquefied gas recovered in the liquefied gas storage tank passes through the ejector,
And cooled in the cooler to be returned to the liquefied gas storage tank. The method according to any one of claims 7 to 9,
When supplying the liquefied gas to the liquefied gas consumer, the liquefied gas supply line is connected to the liquefied gas consumer side,
Wherein the liquefied gas supply line is connected to the liquefied gas storage tank side when the liquefied gas supply line is cooled down. The method according to any one of claims 7 to 9,
Wherein said liquefied gas consumer is a liquefied gas fuel vehicle or a liquefied gas fuel vessel in which demand is intermittently generated.

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