KR102476384B1 - Discharge system and discharge method of liquefied gas - Google Patents

Abstract

[Problem] It is possible to stably discharge liquefied gas remaining in a floating hose on the sea irrespective of the performance of a gas production device that produces gas for discharge. [Solution] The liquefied gas discharge system 5 produces a gas for discharge having a condensation point lower than that of the liquefied gas, and the discharge gas produced by the gas production apparatus 15 A compressor 22 for compressing, a pressure storage container 25 in which the discharge gas compressed by the compressor 22 is filled, and a device for supplying the discharge gas filled in the pressure accumulation container 25 to the floating hose 3 It is set as the structure provided with the line 31 for discharge gas supply.

Description

Discharge system and discharge method of liquefied gas

The present invention relates to a discharge system and discharge method for discharging liquefied gas remaining in a hose at sea after completing the transfer of liquefied gas in a floating hose used for transfer of liquefied gas from a withdrawal facility to a receiving facility. it's about

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

In the past, in the transfer of liquefied gas from land take-out facilities to hulls, from hull to land take-out facilities, or from ship hulls to ship hulls, the hulls are horizontally attached to the wharf attached to the land take-out/take-out facilities, or the transfer of liquefied gas between hulls. In this case, the hulls are horizontally attached to each other and carried out by articulated loading arms or by short flexible hoses. For the purpose of securing safety in the separation operation after completion of the transfer, etc., it is common to carry out a process of discharging liquefied gas remaining in the transfer line connecting the take-out facility and the take-out facility from the transfer line. When discharging liquefied gas from a loading arm or the like, an inert gas (eg, nitrogen gas) is used as the discharging gas.

By the way, in the transfer of liquefied gas between hulls, it is possible only under the condition that the sea is very calm. Therefore, in the case of rough seas, it has been proposed to transport the hulls separated by a safe distance of at least 50m to 300m between the hulls using a floating hose. In addition, as an alternative to the pier accompanying the liquefied gas withdrawal/receiving facility, a transfer facility using a floating hose similar to the liquefied gas transfer between hulls has been proposed.

In the case of using a floating hose, the extraction hose becomes long, and a rising portion occurs at the connection portion between the hull and the hose. In order to discharge LNG (Liquefied Natural Gas) from such a transfer line, since a larger amount of discharge gas is required than before, for example, a gas having a composition equivalent to that of LNG (defrost gas or boil-off gas) A method using a gas (BOG, etc.) is also conceivable. On the other hand, in the case of using a gas having the same composition as LNG as the discharge gas, when the discharge gas is injected into the transfer line, the discharge gas in contact with the cryogenic LNG remaining in the transfer line is rapidly condensed, resulting in hammering There is a possibility that such problems may occur.

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

Patent Document 1: Japanese Unexamined Utility Model Publication No. 5-34399

By the way, in the prior art described in Patent Document 1, it is necessary to prepare an inert gas to be used as a discharge gas, but the purpose is only to discharge the liquefied gas remaining in the loading arm of the transfer line, while FLNG (Floating Liquefied It is not intended for the discharge of liquefied gas remaining in the entire transfer line from the production base containing natural gas) to the carrier and from the carrier to the receiving base. In addition, in order to discharge the liquefied gas remaining in the entire transfer line, the required amount of inert gas increases, but installing an inert gas manufacturing device suitable for the required amount at the production base, carrier ship or receiving base is a problem that does not fit the cost. there is

On the other hand, it is conceivable to divert an inert gas production device used for other purposes in production facilities, carrier ships, or receiving bases, but it is difficult to secure the flow rate or pressure necessary for discharging the liquefied gas remaining in the transfer line. have.

In particular, when a floating hose floating on the sea surface is used for a transfer line, a large height difference occurs along the discharge path of the liquefied gas compared to the case where a loading arm or the like is used (for example, the liquefied gas in the floating hose on the sea Because of the need to push up from the sea level position to the top of the carrier), it may be necessary to ensure a larger flow rate or pressure for the discharged gas.

The present invention has been made in view of the problems of the prior art, and discharge of liquefied gas enabling stable discharge of liquefied gas remaining in a floating hose on the sea regardless of the performance of a gas production device for producing gas for discharge. It is a primary object to provide a system and method of discharge.

In the first aspect of the present invention, in the transfer of liquefied gas from the take-out facility 1 to the receiving facility 2 performed using a floating hose at least partially on the sea, the floating hose 3 used for the transfer A system (5) for discharging liquefied gas remaining in the interior, comprising: a gas production device (15) for producing an exhaust gas having a lower condensation point than the liquefied gas; and compressing the exhaust gas produced by the gas production device. a compressor 22 for supplying the discharge gas compressed by the compressor to the floating hose; It is characterized by having a line 31 for supplying gas.

According to this, by using the pressure accumulator filled with the exhaust gas compressed by the compressor, it is possible to easily secure the flow rate and pressure necessary for the exhaust gas. Therefore, it becomes possible to stably discharge the liquefied gas remaining in the floating hose on the sea regardless of the performance of the gas production device that produces the gas for discharge.

In the second aspect of the present invention, the filling amount of the exhaust gas in the pressure storage container is such that the discharge of the liquefied gas remaining in the floating hose can be completed using the entire amount of the charged exhaust gas. characterized in that it is set.

According to this, since the entire amount of the charged exhaust gas is used for discharging the liquefied gas, control or operation such as stopping delivery of the exhaust gas from the pressure accumulator at an appropriate timing becomes unnecessary. In addition, since adjustment of the usage amount of the exhaust gas becomes easy, excess exhaust gas is sent to the receiving facility, which adversely affects the receiving facility (for example, exceeding the design pressure of the liquefied gas storage tank). that can be prevented Alternatively, problems such as an increase in the inert gas concentration in the boil-off gas can be prevented by excessive discharge gas returning from the receiving facility to the drawing facility as return gas and mixing with the boil-off gas generated from the drawing device. .

In the third aspect of the present invention, the capacity of the pressure storage container is set to be able to charge the amount of the gas for discharge required to discharge the liquefied gas remaining in the floating hose only once. .

According to this, the size of the pressure accumulator can be prevented from being unnecessarily increased, and a compact facility can be realized.

In the fourth aspect of the present invention, a flow rate adjusting device (37, 62, 162) installed in the discharge gas supply line and adjusting the flow rate of the discharge gas supplied from the pressure storage container to the floating hose is further provided. It is characterized by having.

According to this, it is possible to easily realize the flow rate required for the gas for discharge, and more stably discharge the liquefied gas remaining in the floating hose on the sea.

In the fifth aspect of the present invention, the liquefied gas is liquefied natural gas, and the exhaust gas is nitrogen.

According to this, it becomes easy to divert the nitrogen gas manufacturing apparatus used for other uses in the liquefied natural gas withdrawal facility or receiving facility.

In the sixth aspect of the present invention, it is characterized in that the pressure accumulator is installed in the take-out facility or the take-up facility together with the winding device 4 of the floating hose.

According to this, since the floating hose used for transporting the liquefied gas is limited, it is possible to more reliably set the size required for the pressure accumulator.

In the seventh aspect of the present invention, the discharge gas supply line is characterized in that it is connected to the liquefied gas transfer line 32 to which the floating hose is connected in the drawing facility or the receiving facility.

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

In the eighth aspect of the present invention, installed on the upstream side of the connection portion 33 of the discharge gas supply line in the liquefied gas transfer line, to block the supply of the liquefied gas to the floating hose. It is characterized by further comprising a shutoff valve 51.

According to this, a part of the liquefied gas transfer line can be used for discharging the liquefied gas, and the system configuration is simplified.

In the ninth aspect of the present invention, in the transfer of liquefied gas from the take-out facility 1 to the receiving facility 2 performed using a floating hose at least partially on the sea, the floating hose 3 used for the transfer A method of discharging a liquefied gas remaining in the interior, comprising: a manufacturing process of producing a gas for discharge having a condensation point lower than that of the liquefied gas; a compression process of compressing the gas for discharge produced in the manufacturing process; A filling step of filling the pressure storage container 25 with the compressed exhaust gas, and a discharge process of discharging the liquefied gas remaining in the floating hose by supplying the exhaust gas filled in the pressure storage container to the floating hose. It is characterized in that it includes.

According to this, by filling the pressure accumulator with the exhaust gas compressed by the compressor, it is possible to easily secure the flow rate and pressure necessary for the exhaust gas. Therefore, it becomes possible to stably discharge the liquefied gas remaining in the floating hose on the sea irrespective of the performance of the gas production device that performs the production process of producing the gas for discharge.

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 storage container in the filling step.

According to this, since the entire amount of the charged exhaust gas is used for discharging the liquefied gas, control or operation such as stopping delivery of the exhaust gas from the pressure accumulator at an appropriate timing becomes unnecessary. Moreover, since adjustment of the usage amount of exhaust gas becomes easy, it is possible to prevent an adverse effect on the receiving facility by sending excessive exhaust gas to the receiving facility. Alternatively, problems such as an increase in the inert gas concentration in the boil-off gas can be prevented by excessive discharge gas returning from the receiving facility to the drawing facility as return gas and mixing with the boil-off gas generated from the drawing device. .

Thus, according to the present invention, it becomes possible to discharge the liquefied gas remaining in the floating hose on the sea by a simple configuration.

1 is an explanatory diagram showing an application example of a liquefied gas discharge system according to an embodiment;
Fig. 2 is a configuration diagram showing details of a liquefied gas discharge system according to an embodiment;
3 is an explanatory diagram showing a method of discharging LNG remaining in the floating hose;
Fig. 4 is a block diagram showing a modified example of the liquefied gas discharge system shown in Fig. 2;

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

1 is an explanatory diagram 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. 3 is a floating diagram. It is explanatory drawing which shows the discharge method of the LNG which remains in the hose 3.

In the maritime transport of LNG, as shown in FIG. 1, for example, a floating hose 3 is interposed from an FLNG 1 as a take-out facility for exporting LNG to an LNG carrier 2 as a receiving facility for receiving LNG. Transfer of one LNG is done.

FLNG 1 is a floating body type LNG liquefaction facility, and generates LNG by refining and liquefying natural gas (raw material gas) calculated from a gas field on the seabed at sea. The FLNG 1 is equipped with a floating hose 3 for transporting the generated LNG to an LNG carrier 2 or the like and a take-up device 4 for accommodating it. In addition, FLNG 1 is provided with a discharge system 5 (see Fig. 2) for discharging LNG remaining in the floating hose 3 after completion of the transfer of the LNG.

The floating hose 3 constitutes an LNG transfer line and is made of a known flexible hose used in a state in which at least a part of it is floating on the surface of the sea 6. When LNG is transferred from the FLNG 1 to the LNG carrier 2, the floating hose 3 is unwound from the take-up device 4 toward the anchored LNG carrier 2, and as shown in FIG. 1, The hose end part 7 is connected to the LNG ship 2 (in more detail, a piping for receiving LNG not shown).

In addition, the floating hose 3 includes two LNG supply hoses 3A for supplying LNG from the FLNG 1 to the LNG carrier 2, and the return gas from the LNG carrier 2 side to the FLNG 1 ) is composed of one return gas hose 3B for return. However, the configuration of the floating hose 3 (number of hoses, diameter, length, etc.) can be changed in various ways.

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

As shown in FIG. 2 , the discharge system 5 includes a nitrogen producing device (gas producing device) 15 that produces nitrogen having a lower condensation point than LNG. Nitrogen produced by this nitrogen production device 15 is usually used, for example, for sealing the lubricating oil of the compressor in the FLNG 1, for preventing backflow of air in the main piping in the flare-vent facility, and for maintenance. It can be used for purging of combustible gas in the city, etc. Here, nitrogen produced by the nitrogen production device 15 is used as the exhaust gas for discharging the liquefied gas remaining in the floating hose 3. Further, the nitrogen used as the exhaust gas may be a gas containing nitrogen to a degree that does not affect its characteristics (in particular, having a condensation point lower than that of the liquefied gas).

In this way, by using nitrogen as the discharge gas, it becomes possible to divert the already installed nitrogen production device 15 used for other purposes in the FLNG 1. In addition, since nitrogen has a lower condensation point than LNG, it is rapidly condensed even when it comes into contact with the cryogenic LNG remaining in the floating hose 3, so that troubles such as hammering do not occur.

Further, in the exhaust system 5, the nitrogen produced by the nitrogen production device 15 is compressed (ie, the pressure is increased) 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 accumulator 25 via the nitrogen transport pipe 24 provided with the valve 23 . As a result, the pressure accumulator 25 is filled with nitrogen at a higher pressure than the nitrogen produced by the nitrogen production device 15 .

Furthermore, in the discharge system 5, the nitrogen filled in the pressure storage container 25 passes through the nitrogen transport pipe (gas supply line for discharge) 31 through the floating hose 3 (LNG supply hose 3A). supplied to More specifically, the downstream end of the nitrogen transport pipe 31 extends to the connection site 33 to the LNG transport pipe (liquefied gas transport line) 32 used at the time of transporting LNG, whereby , Nitrogen from the pressure accumulator 25 is supplied to the floating hose 3 via a part of the LNG transportation pipe 32 (the downstream part of the connection part 33 in the LNG transportation pipe 32). With this structure, it becomes possible to easily move 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 regulator 35 includes a flow meter 36 that detects the flow rate of nitrogen supplied to the floating hose 3, and is disposed upstream of the flow meter 36, based on the detection value of the flow meter 36 to obtain nitrogen. A flow control valve 37 for controlling the flow rate is installed. Furthermore, in the flow rate adjusting unit 35, valves 38 and 39 are arranged so as to interpose the flow meter 36 and the flow control valve 37.

With this flow rate adjusting unit 35, the flow rate of nitrogen required for discharging the LNG remaining in the floating hose 3 can be easily realized, and it becomes possible to discharge the LNG more stably. In addition, the pressure of the pressure accumulator 25 can be detected by the pressure gauge 42 connected to the nitrogen transport pipe 31 (or the pressure accumulator 25) via the valve 41.

In the LNG transport pipe 32, valves 51 and 52 are provided on the upstream and downstream sides 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 (LNG supply hose 3A). In addition, in FIG. 2, the winding device 4 in which the floating hose 3 is accommodated is abbreviate|omitted.

In the discharge system 5, before the LNG transfer process from the FLNG 1 to the LNG carrier 2 is performed, nitrogen in an amount required for the transfer process is previously produced by the nitrogen production device 15 (manufacturing process). The produced nitrogen is sequentially compressed by the compressor 22 (compression process) and is sequentially introduced into the pressure accumulator 25 (filling process). At this time, the valve 23 of the nitrogen transport pipe 24 is in an open state, and the valves 38 and 39 of the nitrogen transport pipe 31 are in a closed state.

Thereafter, when filling of the pressure storage container 25 with nitrogen at a prescribed pressure (or capacity) is completed, the valve 23 is closed, and preparation for the process of discharging LNG from the floating hose 3 is completed.

Next, in the LNG transfer process, 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 ship 2 is returned to the FLNG 1 side via the hose 3B for return gas.

When the transfer process is completed, the valve (blocking valve) 51 is closed while leaving the valve 52 open. At this time, since the inside of the floating hose 3 is almost filled with the remaining LNG, before the floating hose 3 is separated from the LNG carrier 2, the remaining LNG is discharged from the floating hose 3. A process (discharge process) is required.

In the LNG discharge process, the valves 38 and 39 are opened, and nitrogen is supplied from the pressure storage container 25 to the floating hose 3 (LNG supply hose 3A) by opening the valve 37. do. Thereby, as shown in FIG. 3, the LNG in the floating hose 3 is pushed out slowly toward 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 in the pressure accumulator 25 is reduced to a pressure close to that of the floating hose, and the valves 38 and 39 are closed to complete the process of discharging the LNG. .

In this way, in the LNG discharge system 5, by using the pressure accumulator 25 filled with discharge gas (here, nitrogen), the flow rate and pressure necessary for discharging LNG from the floating hose 3 can be easily adjusted. can be secured Therefore, regardless of the performance of the nitrogen production device 15 (that is, even when it is difficult to discharge LNG from the floating hose 3 with the flow rate or pressure of nitrogen from the existing nitrogen production device 15), It becomes possible to stably discharge the LNG remaining in the floating hose 3 of .

In this case, the filling amount of nitrogen in the pressure accumulator 25 may be set so that the process of discharging LNG remaining in the floating hose 3 can be completed using the entire amount of the filled nitrogen. This eliminates the need for control or operation, such as stopping delivery of nitrogen from the pressure accumulator 25 at an appropriate timing. In addition, since adjustment of the amount of nitrogen used as exhaust gas becomes easy, excess nitrogen is sent to the LNG carrier 2, which adversely affects the facilities of the LNG carrier 2 (for example, the LNG tank 11 ) exceeding the design pressure of) can be prevented. Furthermore, excess nitrogen is returned to the FLNG 1 as a return gas through the return gas hose 3B, thereby mixing with the boil-off gas generated from the drawing facility to increase the inert gas concentration in the boil-off gas. Trouble can be prevented. Further, in the discharging step, when the pressure of nitrogen in the pressure accumulator 25 (for example, the pressure of the pressure gauge 42) becomes equal to or less than a predetermined pressure, it can be judged that the entire amount of filled nitrogen has been used.

In addition, the capacity of the pressure accumulator 25 may be set so that the amount of nitrogen necessary for carrying out the discharge process of the LNG remaining in the floating hose 3 only once can be filled. This prevents the size (capacity) of the pressure accumulator 25 from being unnecessarily large, and a compact facility can be realized.

In addition, the pressure storage container 25 may be installed in the FLNG 1 (or the LNG ship 2) together with the winding device 4 of the floating hose 3. In this way, since the floating hose 3 used for transporting LNG is limited, it is possible to more reliably set the size required for the pressure storage container 25 . Therefore, it is possible to more stably discharge the LNG remaining in the floating hose 3 on the sea.

(Example 1)

Next, simulation results based on CFD analysis regarding the discharging process by the above-described LNG discharging system 5 will be described. Here, for the floating hose 3, the inner diameter is 20 inches, the length is 280 m, and the height difference between the sea surface and the hose distal end 7 on the LNG carrier 2 side (see length H in FIG. 3) is 25 m. In addition, regarding the supply conditions of nitrogen from the pressure accumulator 25 to the floating hose 3, the pressure was set to 3.0 bara (0.3 MPa) and the flow rate was set to 3.0 kg/s (about 8600 Nm 3 /h).

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

In order to prevent excessive flow of nitrogen on the side of the LNG carrier 2, the total amount of nitrogen supplied is about 56 m 3 under conditions of -163° C. and 3.0 bara nitrogen. In this case, as for the pressure accumulator 25, if the conditions for accumulating nitrogen are 30°C and 25 bara (2.5 MPa), and the pressure of nitrogen in the accumulator 25 after the discharge step is 4.0 bara, Regarding the size of the pressure accumulator 25, 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 addition, in the general nitrogen production device 15, for example, the pressure of nitrogen produced is 6 to 8 bara, and the supply amount is about 1000 to 2000 Nm3/h, so it is insufficient to use LNG as it is for discharge. .

(Example 2)

Simulation results in the case where the shape of the floating hose 3 is changed under the same nitrogen supply conditions as in Example 1 described above will be described. Here, about the floating hose 3, the inner diameter was 6 inches, the length was 280 m, and the height difference between the sea surface and the hose distal end 7 on the LNG carrier 2 side was 15 m.

Similarly to the above, in order to prevent a large amount of nitrogen from leaking to the LNG carrier 2 side, the total amount of nitrogen supplied is 5.2 m 3 under the conditions of -163 ° C. and 3.0 bara nitrogen. Regarding the size of the pressure accumulator 25, for example, the inner diameter of the cylindrical cross section can be 1000 mm, and the length between tangent lines can be 2500 mm.

Moreover, the discharge system 5 is not limited to the example mentioned above, It is possible to perform the discharge process with respect to the floating hose 3 and the receiving equipment 2 of various forms.

FIG. 4 is a configuration diagram showing a modified example of the liquefied gas discharging system 5 shown in FIG. 2 . Here, the same reference numerals are assigned to components that are the same as those of the discharge system 5 shown in FIG. 2 . In addition, matters not specifically mentioned below are the same as those of the discharge system 5 shown in FIG. 2 .

The discharge system 5 of the modified example shown in FIG. 4 differs from the discharge system 5 shown in FIG. 2 in the configuration of the flow rate regulator 35 . In the flow rate regulator 35 of the nitrogen transport pipe 31, a restriction orifice 62 is provided on the downstream side of the valve 38, and further from the main body of the nitrogen transport pipe 31 on the upstream side of the valve 38. Branch pipe 131 branched and extended in parallel is provided with the same configuration (valve 138 and limiting orifice 162). 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 process of discharging LNG, the valves 38 and 39 are first opened, the pressure in the pressure storage container slowly decreases, and then the valve 138 is opened, and the nitrogen supplied to the floating hose 3 is released. The flow rate is regulated by a plurality of restricting orifices (62, 162).

As mentioned above, although this invention was demonstrated based on specific embodiment, these embodiment are only examples, and this invention is not limited by these embodiment. In the above-described embodiment, an example was shown in which FLNG was used as a take-out facility and an LNG carrier was used as a receiving facility, but it is not limited to this, and any facility (for example, , FSO (Floating Storage & Offloading Unit): floating storage and extraction facility, FSU (Floating Storage Unit): floating LNG receiving base, FSRU (Floating Storage & Regasification Unit): floating storage regasification facility, FPSO (Floating Production, Storage & Offloading Unit): Floating production, storage and extraction facilities, etc.) can be take-out and take-out facilities, respectively. In addition, a configuration in which one of the take-out facility and the take-out facility is installed on land is also possible.

In addition, in the above-described embodiment, although the liquefied gas to be discharged is LNG, other liquefied gases (eg, LPG (Liquefied Petroleum Gas)) are not limited to this, as long as transfer using at least a floating hose is possible. It can be used as an emission target.

In addition, in the above-described embodiment, an example in which nitrogen is used as the gas for discharge has been shown, but it is not limited to this, and other gases (for example, other than An inert gas or a mixed gas thereof) may be used.

In addition, in the above-described embodiment, an example in which the LNG discharge system 5 is installed on the drawing facility (FLNG(1)) side has been shown, but is not limited to this, and at least a part of the components of the discharge system 5 A configuration installed on the receiving facility (LNG ship 2) side is also possible. In that case, discharge|discharge of LNG can be performed so that the LNG which remains in 3 A of hoses for LNG supply may reversely flow with respect to a transfer direction.

In addition, not all of the components of the liquefied gas discharging system and discharging method according to the present invention shown in the above-described embodiment are necessarily all, and at least it is possible to select them appropriately without departing from the scope of the present invention. .

1: FLNG (take-off facility)
2: LNG carrier (acquisition facility)
3: floating hose
3A: Hose for supplying LNG
3B: Hose for return gas
4: winding device
5: Exhaust system
7: hose end
11: LNG tank
15: nitrogen production device
21: nitrogen transport pipe
22: Compressor
23: valve
24: nitrogen transport pipe
25: pressure accumulator
31: nitrogen transport pipe (line for supplying exhaust gas)
32: LNG transport pipe (line for transporting liquefied gas)
33: connection part
35: flow control unit
36: flow meter
37: flow control valve (flow regulating device)
38: valve
39: valve
41: valve
42: pressure gauge
51: valve
52: valve
53: downstream
54: upstream
62: limiting orifice (flow adjusting device)
131: bypass line
138: valve
162: limiting orifice (flow adjusting device)

Claims (10)

In the transfer of liquefied gas from a fetching facility to a receiving facility by using a floating hose at least part of which is on the sea, the liquefied gas remaining in the floating hose used for the transfer is discharged from the fetching facility to the receiving facility. As a discharge system for liquefied gas,
A gas production device for producing a gas for discharge having a lower condensation point than the liquefied gas;
a compressor for compressing the exhaust gas produced by the gas production device;
a pressure accumulator into which the exhaust gas compressed by the compressor is filled;
A discharge gas supply line for supplying the discharge gas filled in the pressure storage container to the floating hose;
The capacity of the pressure storage container is set to be able to fill the amount of the gas for discharge required to discharge the liquefied gas remaining in the floating hose only once,
The liquefied gas discharge system according to claim 1 , wherein the pressure storage container is installed in the drawing facility together with the winding device of the floating hose. The method of claim 1,
Liquefied gas, characterized in that the filling amount of the gas for discharge in the pressure accumulator is set so that the discharge of the liquefied gas remaining in the floating hose can be completed using the entire amount of the charged gas for discharge. of the exhaust system. According to claim 1 or claim 2,
The liquefied gas discharge system according to claim 1, further comprising a flow rate adjusting device installed in the discharge gas supply line and adjusting a flow rate of the discharge gas supplied from the pressure storage container to the floating hose. According to claim 1 or claim 2,
The liquefied gas is a liquefied natural gas, and the discharge gas is nitrogen. According to claim 1 or claim 2,
The liquefied gas discharge system characterized in that the discharge gas supply line is connected to a liquefied gas transfer line to which the floating hose is connected in the take-out facility in which the retractor is installed. The method of claim 5,
It is installed on the upstream side of the connection part of the discharge gas supply line in the liquefied gas transfer line, and further comprising a shutoff valve for blocking the supply of the liquefied gas to the floating hose. Discharge system for liquefied gas. In the transfer of liquefied gas from a fetching facility to a receiving facility by using a floating hose at least part of which is on the sea, the liquefied gas remaining in the floating hose used for the transfer is discharged from the fetching facility to the receiving facility. As a method of discharging liquefied gas to
A manufacturing process of producing a gas for discharge having a lower condensation point than the liquefied gas;
a compression step of compressing the exhaust gas produced in the manufacturing step;
a filling step of filling a pressure accumulator with the exhaust gas compressed in the compression step;
a discharge step of discharging the liquefied gas remaining in the floating hose by supplying the discharge gas filled in the pressure storage container to the floating hose;
The capacity of the pressure storage container is set to be able to fill the amount of the gas for discharge required to discharge the liquefied gas remaining in the floating hose only once,
The method of discharging liquefied gas, characterized in that the pressure storage container is installed in the drawing facility together with the winding device of the floating hose. The method of claim 7,
The liquefied gas discharge method according to claim 1 , wherein the discharging step is performed using the entire amount of the discharging gas filled in the pressure storage container in the filling step. delete delete

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