WO2019004280A1

WO2019004280A1 - Liquefied gas discharge system and discharge method

Info

Publication number: WO2019004280A1
Application number: PCT/JP2018/024357
Authority: WO
Inventors: 直樹渡邊; 常則風間; 和宏星野; 俊浩江藤; 良治小木曽; 基樹入倉; 隆寛石神
Original assignee: 千代田化工建設株式会社
Priority date: 2017-06-30
Filing date: 2018-06-27
Publication date: 2019-01-03
Also published as: JP2019011814A; JP6709195B2; CN110869663B; KR20200015727A; KR102476384B1; CN110869663A

Abstract

[Problem] To enable stable discharge of liquefied gas remaining in a floating hose on the sea, regardless of the capability of a gas producing device which produces a discharge gas. [Solution] A liquefied gas discharge system 5 consists of: a gas producing device 15 which produces a discharge gas having a condensation point lower than that of liquefied gas; a compressor 22 which compresses the discharge gas produced by the gas producing device 15; a pressure accumulating vessel 25 which is filled with the discharge gas that has been compressed by the compressor 22; and a discharge gas supply line 31 for supplying the discharge gas with which the pressure accumulating vessel 25 has been filled to a floating hose 3.

Description

Liquefied gas discharge system and method

The present invention relates to a discharge system and a discharge method for discharging liquefied gas remaining in a hose at sea after completing transfer of liquefied gas in a floating hose used for transferring liquefied gas from a delivery facility to a receiving facility. About.

Natural gas consists mostly of methane and the other major constituents are nitrogen, ethane, propane and butane. As liquefied gas, there is LPG which is a single component or mixed component of each of LNG, ethane, propane and butane which is a main component of methane.

Conventionally, in the transfer of liquefied gas from the land dispensing facility to the hull, from the hull to the land receiving facility or from the hull to the hull, the hull is attached to a jetty attached to the land dispensing / receiving facility or in the case of liquefied gas transfer between hulls. The hulls are placed side-by-side and implemented by means of an articulated loading arm or by means of a flexible hose of short length. In order to ensure the safety in the separation operation after completion of the transfer, a step of discharging the liquefied gas remaining in the transfer line connecting the dispensing facility and the receiving facility from the transfer line is generally performed. When discharging the liquefied gas from the loading arm or the like, an inert gas (nitrogen gas or the like) is used as a discharging gas.

However, it is possible to arrange the hulls side by side with liquefied gas transfer between the hulls only under the condition that the sea is extremely quiet. Therefore, in the case of a rough sea, it has been proposed to use a floating hose to separate and transport the hulls by a safe distance of at least 50 m to 300 m. Also, as an alternative to a jetty attached to a liquefied gas land delivery / reception facility, a transfer facility using a floating hose similar to liquefied gas transfer between hulls has been proposed.

When a floating hose is used, the delivery hose becomes longer and there is a rising portion at the connection between the hull and the hose. In order to discharge LNG (Liquefied Natural Gas) or the like from such a transfer line, a large amount of gas for discharge is required as compared with the prior art, for example, a gas having the same composition as LNG (Defrost Gas) Alternatively, a method using boil-off gas (BOG) or the like may be considered. On the other hand, when a gas having the same composition as that of LNG is used as the discharge gas, the discharge gas in contact with the cryogenic LNG remaining in the transfer line when the discharge gas is injected into the transfer line is Rapid condensation may cause troubles such as hammering.

On the other hand, a technology using an inert gas (nitrogen gas etc.) as a discharge gas is known, for example, after transferring liquefied gas from a tank of a carrier ship to a receiving base, the inside of a loading arm constituting a transfer line is There is a technique for automatically replacing with an inert gas (see Patent Document 1).

Japanese Utility Model Application Publication No. 5-34399

By the way, in the prior art described in the above-mentioned patent documents 1, although it is necessary to prepare the inactive gas used as gas for discharge, it aims only at discharging the liquefied gas which remains in the loading arm of a transfer line. It does not aim at the discharge of liquefied gas remaining in the whole transfer line from the production base including the LNG LNG (Floating Liquefied Natural Gas) to the carrier and from the carrier to the receiving base. Also, in order to discharge the liquefied gas remaining in the entire transfer line, the amount of inert gas required increases, but the apparatus for manufacturing inert gas that meets the amount required for production bases, carriers and receiving bases There is a problem that the installation of is not worth the cost.

On the other hand, it is also conceivable to divert inert gas production equipment used in other applications in production facilities, carrier vessels or receiving bases, but to secure the flow rate and pressure necessary for discharging the liquefied gas remaining in the transfer line. There is a problem that it is difficult.

In particular, when a floating hose floating on the sea surface is used as a transfer line, a large difference in elevation occurs depending on the discharge path of liquefied gas as compared to the case of using a loading arm or the like (for example, liquefied gas in floating hose on the sea Because it is necessary to push up from the sea level position onto the carrier vessel), it may be necessary to secure a larger flow rate and pressure for the exhaust gas.

The present invention has been made in view of the problems of the prior art as described above, and the liquefied gas remaining in the floating hose on the sea is stabilized regardless of the performance of the gas producing apparatus for producing the exhaust gas. The main object of the present invention is to provide a system and method for discharging liquefied gas that can be discharged.

In the first aspect of the present invention, the floating hose used for the transfer of liquefied gas from the discharge facility (1) to the receiving facility (2) which is performed using a floating hose at least a part of which is on the sea (3) A discharge system (5) for liquefied gas remaining in the gas, the gas production apparatus (15) producing a discharge gas having a condensation point lower than the liquefied gas, and the gas production apparatus A compressor (22) for compressing the exhaust gas, an accumulator container (25) filled with the exhaust gas compressed by the compressor, and the floating hose charged with the exhaust gas filled in the accumulator container And an exhaust gas supply line (31) for supplying the hydrogen gas.

According to this, it is possible to easily secure the flow rate and pressure necessary for the discharge gas by using the pressure accumulation container filled with the discharge gas compressed by the compressor. Therefore, regardless of the performance of the gas producing apparatus producing the exhaust gas, it is possible to stably discharge the liquefied gas remaining in the floating hose on the sea.

In the second aspect of the present invention, the filling amount of the discharge gas in the pressure accumulation container can complete the discharge of the liquefied gas remaining in the floating hose by using the entire amount of the discharge gas charged. It is characterized in that it is set.

According to this, since the entire amount of the discharged gas for filling is used for discharging the liquefied gas, control or operation such as stopping the delivery of the gas for discharge from the pressure accumulation container at an appropriate timing becomes unnecessary. In addition, since it becomes easy to adjust the amount of exhaust gas used, excessive exhaust gas is sent to the receiving facility, which adversely affects the receiving facility (for example, the design pressure of the storage tank for liquefied gas is exceeded) Can be prevented. Alternatively, the excess exhaust gas is returned from the receiving facility to the dispensing facility as a return gas and mixed with the boil-off gas generated from the dispensing facility to prevent problems such as an increase in the concentration of inert gas in the boil-off gas. Can.

In the third aspect of the present invention, the capacity of the pressure accumulation container can be filled with the amount of the discharge gas necessary to discharge the liquefied gas remaining in the floating hose only once. It is characterized by being set.

According to this, the size of the pressure accumulation container is prevented from being unnecessarily increased, and a compact installation can be realized.

According to a fourth aspect of the present invention, there is provided a flow control device (37, 62, 162) which is provided in the discharge gas supply line and adjusts the flow rate of the discharge gas supplied from the pressure accumulation container to the floating hose. Furthermore, it is characterized by having.

According to this, the flow rate necessary for the exhaust gas can be easily realized, and the liquefied gas remaining in the floating hose on the sea can be discharged more stably.

According to a fifth aspect of the present invention, the liquefied gas is liquefied natural gas, and the gas for discharge is nitrogen.

According to this, it becomes easy to divert the production equipment of nitrogen gas used for other uses in the delivery facility or receiving facility of liquefied natural gas.

A sixth aspect of the present invention is characterized in that the pressure accumulation container is installed in the dispensing facility or the receiving facility together with a device (4) for winding the floating hose.

According to this, since the floating hose used for transfer of liquefied gas is limited, the size required for the pressure accumulation container can be set more reliably.

In the seventh aspect of the present invention, the exhaust gas supply line is connected to a liquefied gas transfer line (32) to which the floating hose is connected in the dispensing facility or the receiving facility. .

According to this, it is possible to easily shift to the discharge process of the liquefied gas after the transfer process of the liquefied gas is completed.

In the eighth aspect of the present invention, it is provided on the upstream side of the connection portion (33) of the discharge gas supply line in the liquefied gas transfer line, and blocks the supply of the liquefied gas to the floating hose. And a shutoff valve (51).

According to this, a part of the liquefied gas transfer line can be diverted for discharging the liquefied gas, and the system configuration becomes simple.

In the ninth aspect of the present invention, the floating hose used for the transfer of liquefied gas from the dispensing facility (1) to the receiving facility (2) which is performed using a floating hose at least a part of which is on the sea (3) A method of discharging liquefied gas remaining in the inside, comprising: a manufacturing step of manufacturing a discharge gas having a condensation point lower than that of the liquefied gas; and compressing the discharge gas manufactured in the manufacturing step A compression step, a filling step of filling the pressure-accumulating container (25) with the discharge gas compressed in the compression step, and supplying the discharge gas filled in the pressure-storage container to the floating hose; And D. discharging the liquefied gas remaining in the floating hose.

According to this, it is possible to easily secure the flow rate and pressure necessary for the discharge gas by filling the discharge gas compressed by the compressor into the pressure accumulation container. Therefore, regardless of the performance of the gas production apparatus that carries out the production process for producing the exhaust gas, it is possible to stably discharge the liquefied gas remaining in the floating hose on the sea.

A tenth aspect of the present invention is characterized in that the discharging step is performed using the entire amount of the discharging gas filled in the pressure accumulation container in the filling step.

According to this, since the entire amount of the discharged gas for filling is used for discharging the liquefied gas, control or operation such as stopping the delivery of the gas for discharge from the pressure accumulation container at an appropriate timing becomes unnecessary. In addition, since it is easy to adjust the amount of exhaust gas used, it is possible to prevent the adverse effect on the receiving facility by sending the excess exhaust gas to the receiving facility. Alternatively, the excess exhaust gas is returned from the receiving facility to the dispensing facility as a return gas and mixed with the boil-off gas generated from the dispensing facility to prevent problems such as an increase in the concentration of inert gas in the boil-off gas. Can.

As described above, according to the present invention, it is possible to discharge liquefied gas remaining in the floating hose on the sea with a simple configuration.

Explanatory drawing which shows the application example of the discharge system of the liquefied gas which concerns on embodiment. The block diagram which shows the detail of the discharge system of liquefied gas concerning an embodiment Explanatory drawing which shows the discharge method of LNG which remains in a floating hose The block diagram which shows the modification of the discharge system of the liquefied gas shown in FIG. 2

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view showing an application example of a liquefied gas discharge system 5 according to an embodiment of the present invention, FIG. 2 is a configuration diagram showing details of the liquefied gas discharge system 5, and FIG. It is explanatory drawing which shows the discharge method of LNG which remains inside.

In the sea transportation of LNG, for example, as shown in FIG. 1, the transfer of the LNG via the floating hose 3 to the LNG carrier 2 as a receiving facility for receiving the LNG from the FLNG 1 as a dispensing facility for discharging the LNG is performed.

FLNG 1 is a floating type LNG liquefaction facility, and produces LNG by purifying and liquefying natural gas (raw material gas) produced from a gas field on the seabed. The FLNG 1 includes a floating hose 3 for transferring the produced LNG to the LNG ship 2 or the like, and a winding device 4 for housing the same. Further, the FLNG 1 is provided with a discharge system 5 (see FIG. 2) for discharging the LNG remaining in the floating hose 3 after the transfer of the LNG is completed.

The floating hose 3 constitutes a transfer line of LNG, and consists of a known flexible hose used in a state in which at least a part thereof is suspended on the sea surface 6. When LNG is transferred from the FLNG 1 to the LNG carrier 2, the floating hose 3 is delivered from the winding device 4 toward the anchored LNG container 2, and as shown in FIG. 2 (more specifically, it is in a state of being connected to a piping for receiving LNG not shown).

The floating hose 3 also includes two LNG supply hoses 3A for supplying LNG from the FLNG 1 to the LNG carrier 2, and one hose for return gas for returning the return gas from the LNG carrier 2 side to the FLNG 1 And 3B. However, the configuration of the floating hose 3 (number of hoses, diameter, length, etc.) can be variously changed.

The LNG vessel 2 is a known LNG tanker used for transporting LNG, and includes an LNG tank 11 capable of storing LNG transferred from the FLNG 1.

As shown in FIG. 2, the discharge system 5 includes a nitrogen production apparatus (gas production apparatus) 15 that produces nitrogen having a condensation point lower than that of LNG. The nitrogen produced by the nitrogen producing apparatus 15 is generally used, for example, for sealing lubricants of compressors in FLNG 1, for preventing backflow of air in main piping in flare and vent equipment, and for combustible gas at maintenance. It can be used for purging and the like. Here, nitrogen produced by the nitrogen producing apparatus 15 is used as a discharge gas for discharging the liquefied gas remaining in the floating hose 3. The nitrogen used as the exhaust gas may be a gas containing nitrogen that does not affect the characteristics (in particular, having a condensation point lower than that of the liquefied gas).

As described above, by using nitrogen as the exhaust gas, it becomes possible to divert the existing nitrogen production device 15 used for other applications in the FLNG 1. Further, since nitrogen has a condensation point lower than that of LNG, it does not rapidly condense even when contacting with cryogenic LNG remaining in the floating hose 3 to cause troubles such as hammering.

Further, in the discharge system 5, the nitrogen produced by the nitrogen production apparatus 15 is compressed (that is, boosted) by being introduced into the compressor 22 through the nitrogen transport pipe 21. Furthermore, the nitrogen compressed by the compressor 22 is introduced into the pressure accumulation container 25 via the nitrogen transport pipe 24 provided with the valve 23. As a result, the pressure accumulation container 25 is filled with nitrogen at a pressure higher than that of the nitrogen produced by the nitrogen production apparatus 15.

Furthermore, in the discharge system 5, the nitrogen filled in the pressure accumulation container 25 is supplied to the floating hose 3 (hose 3A for supplying LNG) through the nitrogen transport pipe (line for supplying the discharge gas) 31. More specifically, the downstream end of the nitrogen transport pipe 31 extends to the connection site 33 to the LNG transport pipe (line for liquefied gas transport) 32 used in the transfer of LNG, whereby Nitrogen is supplied to the floating hose 3 through a part of the LNG transport pipe 32 (a downstream portion of the connection portion 33 in the LNG transport pipe 32). With such a configuration, it is possible to easily shift to the LNG discharge process after the LNG transfer process described later is completed.

In addition, the nitrogen transport pipe 31 is provided with a flow rate adjusting unit (flow rate adjusting device) 35 for adjusting the flow rate of nitrogen supplied to the floating hose 3. The flow rate adjustment unit 35 includes a flow meter 36 for detecting the flow rate of nitrogen supplied to the floating hose 3 and an upstream side of the flow meter 36, and controls the nitrogen flow rate based on the detection value of the flow meter 36. A flow control valve 37 is provided. Furthermore, in the flow rate adjustment unit 35, the

valves

38 and 39 are disposed so as to sandwich the flow meter 36 and the flow control valve 37.

Such a flow rate adjusting unit 35 can easily realize the flow rate of nitrogen required for discharging the LNG remaining in the floating hose 3, and can discharge the LNG more stably. The pressure of the pressure accumulation container 25 can be detected by a pressure gauge 42 connected to the nitrogen transport pipe 31 (or pressure accumulation container 25) via the valve 41.

In the LNG transport pipe 32,

valves

51 and 52 are provided on the upstream side and the downstream side of the connection portion 33, respectively. Moreover, the downstream end 53 of the LNG transport pipe 32 is connected to the upstream end 54 of the floating hose 3 (hose 3A for LNG supply). In FIG. 2, the winding device 4 in which the floating hose 3 is accommodated is omitted.

In the discharge system 5, before the transfer process of the LNG from the FLNG 1 to the LNG vessel 2 is performed, the nitrogen production device 15 manufactures an amount of nitrogen necessary for the transfer process (production process). The produced nitrogen is sequentially compressed by the compressor 22 (compression step) and sequentially introduced into the pressure accumulation container 25 (filling step). At this time, the valve 23 of the nitrogen transport pipe 24 is in the open state, and the

valves

38 and 39 of the nitrogen transport pipe 31 are in the closed state.

Thereafter, when the filling of the pressure storage container 25 with nitrogen is completed at the defined pressure (or volume), the valve 23 is closed, and the preparation of the step of discharging the LNG from the floating hose 3 is completed.

Next, in the LNG transfer step, LNG is supplied from the LNG transport pipe 32 to the LNG supply hose 3A with the

valves

51 and 52 open. At this time, in parallel with the supply of LNG, BOG or the like generated in the LNG vessel 2 is returned to the FLNG 1 side through the return gas hose 3B.

When the transfer process is completed, the valve (shutdown valve) 51 is closed while the valve 52 is kept open. At this time, since the inside of the floating hose 3 is substantially filled with the remaining LNG, the step of discharging the remaining LNG from the floating hose 3 before the floating hose 3 is separated from the LNG vessel 2 (discharge step) Is required.

In the process of discharging the LNG, the

valves

38 and 39 are opened, and the valve 37 is opened to supply nitrogen from the pressure accumulation container 25 to the floating hose 3 (hose 3A for supplying LNG). Thereby, as shown in FIG. 3, the LNG in the floating hose 3 is gradually pushed out to the LNG ship 2 side by the nitrogen supplied from the FLNG 1 side. Finally, when the LNG in the floating hose 3 is replaced with nitrogen, the pressure of the pressure accumulation vessel 25 is reduced to a pressure close to the pressure of the floating hose, and the

valves

38 and 39 are closed to complete the LNG discharge process.

As described above, in the LNG discharge system 5, the flow rate and pressure necessary for discharging the LNG from the floating hose 3 can be easily facilitated by using the pressure storage container 25 filled with the discharge gas (here, nitrogen). It can be secured. Therefore, regardless of the performance of the nitrogen production unit 15 (that is, even if it is difficult to discharge the LNG from the floating hose 3 by the flow rate and pressure of nitrogen from the existing nitrogen production unit 15), It becomes possible to discharge the remaining LNG stably.

In this case, the filling amount of nitrogen in the pressure accumulation container 25 may be set so as to be able to complete the process of discharging the LNG remaining in the floating hose 3 using the total amount of nitrogen charged. As a result, control or operation such as stopping the delivery of nitrogen from the pressure accumulation container 25 at an appropriate timing becomes unnecessary. In addition, since it is easy to adjust the amount of nitrogen used as the exhaust gas, the excess nitrogen is delivered to the LNG carrier 2 to adversely affect the facilities of the LNG carrier 2 (for example, the design of the LNG tank 11 Pressure) can be prevented. Furthermore, excessive nitrogen is returned to FLNG 1 as return gas via return gas hose 3B, thereby preventing troubles such as increasing the concentration of inert gas in the boil-off gas by mixing with boil-off gas generated from the dispensing facility. can do. In the discharging step, when the pressure of nitrogen in the pressure accumulation container 25 (for example, the pressure of the pressure gauge 42) becomes equal to or less than a predetermined pressure, it can be determined that the entire amount of nitrogen charged is used.

In addition, the capacity of the pressure accumulation container 25 may be set so as to be able to be filled with the amount of nitrogen necessary to carry out the process of discharging the LNG remaining in the floating hose 3 only once. As a result, the size (volume) of the pressure accumulation container 25 is prevented from becoming unnecessarily large, and a compact installation can be realized.

Further, the pressure accumulation container 25 may be installed on the FLNG 1 (or the LNG carrier 2) together with the winding device 4 of the floating hose 3. Thereby, since the floating hose 3 used for transfer of LNG is limited, the size required for the pressure accumulation container 25 can be set more reliably. Therefore, the LNG remaining in the floating hose 3 on the sea can be discharged more stably.

Example 1
Next, the simulation result based on the CFD analysis about the discharge process by the above-mentioned discharge system 5 of LNG is explained. Here, for the floating hose 3, the inner diameter was 20 inches, the length was 280 m, and the height difference between the sea surface and the hose end 7 on the LNG vessel 2 side (see length H in FIG. 3) was 25 m. . Moreover, about the supply conditions of nitrogen from the pressure accumulation container 25 to the floating hose 3, the pressure was 3.0 bara (0.3 MPa), and the flow rate was 3.0 kg / s (about 8600 Nm ³ / h).

Under these conditions, in the LNG discharging step, by continuing supplying nitrogen to the floating hose 3 for about 3 minutes, the LNG remaining in the floating hose 3 becomes about 10 vol% or less.

In order to prevent a large amount of nitrogen from flowing to the LNG vessel 2 side, the total supply amount of nitrogen is about 56 m ^{3 under} the condition of nitrogen of -163 ° C. and 3.0 bara. In this case, regarding the pressure accumulation container 25, the pressure accumulation condition of nitrogen is 30 ° C., 25 bara (2.5 MPa), and the pressure of nitrogen in the pressure accumulation container 25 after the discharge step is 4.0 bara. For example, the inner diameter of the cylindrical cross section can be 2300 mm, and the length between tangent lines (see length L in FIG. 2) can be 5000 mm. In the general nitrogen production apparatus 15, for example, the pressure of nitrogen to be produced is 6 to 8 bara, and the supply amount thereof is about 1000 to 2000 Nm ³ / h. Is inadequate.

(Example 2)
The simulation result at the time of changing the form of the floating hose 3 on the supply conditions of nitrogen similar to the above-mentioned Example 1 is demonstrated. Here, as for the floating hose 3, the inner diameter is 6 inches, the length is 280 m, and the height difference between the sea surface and the hose end portion 7 on the LNG vessel 2 side is 15 m.

As described above, in order to prevent the nitrogen vessel 2 from blowing a large amount of nitrogen, the total supply amount of nitrogen is 5.2 m ^{3 under} the conditions of nitrogen of -163 ° C. and 3.0 bara. Further, the size of the pressure accumulation container 25 can be, for example, an inner diameter of a cylindrical cross section and 1000 mm, and a length between tangent lines can be 2500 mm.

In addition, the discharge system 5 can implement a discharge process with respect to the floating hose 3 and the receiving installation 2 of various forms not only in the above-mentioned example.

FIG. 4 is a block diagram showing a modification of the liquefied gas discharge system 5 shown in FIG. Here, the same components as those of the discharge system 5 shown in FIG. 2 are denoted by the same reference numerals. Moreover, about the matter which does not mention in particular below, suppose that it is the same as that of the discharge system 5 shown in FIG.

In the discharge system 5 of the modification shown in FIG. 4, the configurations of the discharge system 5 and the flow rate adjustment unit 35 shown in FIG. 2 are different. A restriction orifice 62 is provided on the downstream side of the valve 38 in the flow rate adjustment unit 35 of the nitrogen transport pipe 31, and a branch pipe 131 which branches from the main body of the nitrogen transport pipe 31 and extends in parallel on the upstream side of the valve 38. A similar arrangement (valve 138 and restriction orifice 162) is also provided. The downstream end of the branch pipe 131 is connected to the main body of the nitrogen transport pipe 31 on the upstream side of the valve 39.

In the LNG discharging process, the

valves

38 and 39 are first opened, and after the pressure in the pressure accumulation container is gradually decreased, the valve 138 is then opened next, and the flow rates of nitrogen supplied to the floating hose 3 are plural. Adjusted by the restriction orifices 62, 162.

Although the present invention has been described above based on the specific embodiments, these embodiments are merely examples, and the present invention is not limited by these embodiments. In the above-described embodiment, an example in which FLNG is used as the dispensing facility and an LNG carrier is used as the receiving facility is shown, but the invention is not limited thereto. Any facility (for example, as long as it can transfer LNG using a floating hose) , FSO (Floating Storage & Offloading Unit): Floating storage and unloading facility, FSU (Floating Storage Unit): Floating LNG receiving base, FSRU (Floating Storage & Regasification Unit): Floating storage and regasification unit, FPSO (FPSO (Floating) Production, Storage & Offloading Unit): A floating production storage and delivery facility etc.) can be the delivery facility and the receiving facility, respectively. It is also possible that one of the dispensing facility and the receiving facility is installed on land.

In the above embodiment, although the liquefied gas to be discharged is LNG, the present invention is not limited to this, but at least as long as transfer is possible using a floating hose, another liquefied gas (for example, LPG (Liquefied Petroleum Gas)) ) May be the target of discharge.

In the above embodiment, an example using nitrogen as the discharge gas is shown, but the present invention is not limited to this, and any other gas (for example, any gas may be used if it has a condensation point lower than at least the liquefied gas to be discharged Inert gases other than nitrogen, or mixtures thereof may be used.

Moreover, in the above-mentioned embodiment, although the example which provided the discharge system 5 of LNG in the discharge | payout apparatus (FLNG1) side was shown, not only this but at least one part of the component of the discharge system 5 is a reception facility (LNG ship 2) A configuration provided on the side is also possible. In that case, the discharge of the LNG can be performed so as to backflow the LNG remaining in the LNG supply hose 3A in the transfer direction.

The components of the liquefied gas discharge system and discharge method according to the present invention described in the above-described embodiment are not necessarily all essential, and can be selected appropriately without departing from the scope of the present invention. It is possible.

1: FLNG (dispensing equipment)
2: LNG carrier (receiving facility)
3: Floating hose 3A: LNG supply hose 3B: return gas hose 4: winding device 5: discharge system 7: hose end 11: LNG tank 15: nitrogen production device 21: nitrogen transport tube 22: compressor 23: valve 24: Nitrogen transport pipe 25: Accumulating container 31: Nitrogen transport pipe (gas supply line for discharge)
32: LNG transport pipe (liquefied gas transfer line)
33: connection portion 35: flow rate adjusting unit 36: flow meter 37: flow control valve (flow adjusting device)
38: Valve 39: Valve 41: Valve 42: Pressure gauge 51: Valve 52: Valve 53: Downstream end 54: Upstream end 62: Restricted orifice (flow regulating device)
131: bypass line 138: valve 162: restricted orifice (flow regulator)

Claims

What is claimed is: 1. A system for discharging liquefied gas remaining in the floating hose used for the transfer of liquefied gas from the dispensing facility to the receiving facility performed using a floating hose at least a part of which is on the sea,
A gas production apparatus for producing an exhaust gas having a condensation point lower than the liquefied gas;
A compressor for compressing the exhaust gas produced by the gas production apparatus;
An accumulator container filled with the exhaust gas compressed by the compressor;
An exhaust gas supply line for supplying the exhaust gas filled in the pressure accumulation container to the floating hose;
A liquefied gas discharge system characterized by comprising.
The filling amount of the discharge gas in the pressure accumulation container is set such that discharge of the liquefied gas remaining in the floating hose can be completed using the entire amount of the discharge gas filled. The system for discharging liquefied gas according to claim 1.
The capacity of the pressure accumulation container is set to be able to be filled with the amount of the discharge gas necessary to carry out the discharge of the liquefied gas remaining in the floating hose only once. The discharge system of the liquefied gas according to claim 1 or claim 2.
4. The fuel cell system according to claim 1, further comprising a flow rate adjusting device provided in the exhaust gas supply line and adjusting the flow rate of the exhaust gas supplied from the pressure accumulation container to the floating hose. The liquefied gas discharge system according to any one of the above.
The liquefied gas discharge system according to any one of claims 1 to 4, wherein the liquefied gas is liquefied natural gas, and the discharge gas is nitrogen.
The liquefied gas discharge system according to any one of claims 1 to 5, wherein the pressure accumulation container is installed in the dispensing facility or the receiving facility together with a device for winding the floating hose.
7. The discharge gas supply line is connected to a liquefied gas transfer line to which the floating hose is connected in the dispensing facility or the receiving facility. Liquefied gas discharge system.
The fuel cell system further includes a shutoff valve provided upstream of the connection portion of the discharge gas supply line in the liquefied gas transfer line, for shutting off the supply of the liquefied gas to the floating hose. The liquefied gas discharge system according to claim 7.
A method of discharging liquefied gas remaining in the floating hose used for the transfer, in transfer of liquefied gas from the delivery facility to the receiving facility performed using a floating hose at least a part of which is on the sea,
A process of manufacturing an exhaust gas having a condensation point lower than the liquefied gas;
A compression step of compressing the exhaust gas produced in the production step;
Filling the storage gas container with the discharge gas compressed in the compression step;
And discharging the liquefied gas remaining in the floating hose by supplying the discharging gas filled in the pressure accumulation container to the floating hose.
The method for discharging liquefied gas according to claim 9, wherein the discharging step is performed using the whole amount of the discharging gas filled in the pressure accumulation container in the filling step.