CN118090269A

CN118090269A - Multi-cabin replacement system and method for gas ship

Info

Publication number: CN118090269A
Application number: CN202410090508.9A
Authority: CN
Inventors: 贺隆坤; 董三国; 王哲; 张成友
Original assignee: Jiangnan Shipyard Group Co Ltd; China State Shipbuilding Corp Ltd
Current assignee: Jiangnan Shipyard Group Co Ltd; China State Shipbuilding Corp Ltd
Priority date: 2024-01-23
Filing date: 2024-01-23
Publication date: 2024-05-28

Abstract

The application provides a multi-cabin replacement system and a multi-cabin replacement method for a gas ship. The system comprises a tank car, a filling pipe, a condensing pipe, an auxiliary filling pipe, an exhaust pipe and a flare stack. The tank car is used for loading liquefied gas; the filling pipe is connected with the tank car and the fourth cargo tank, the condensing pipe is used for connecting the fourth cargo tank with the tank car, the condensing pipe is connected with the filling pipe in parallel, and the auxiliary filling pipe is connected between the filling pipe and the condensing pipe; the exhaust pipe is connected between two adjacent cargo tanks. According to the application, the plurality of cargo tanks are connected in series through the exhaust pipe, and cargo vapor generated in the processes of replacing the front cargo tank, the cold cargo tank and filling is fully utilized to replace the rear cargo tank, so that the replacement of the other cargo tanks is completed while the liquid cargo is filled in the cold cargo tank, and additional cargo is not consumed, thereby realizing the efficient utilization of the cargo vapor; the tank wagon is connected with one cargo tank, so that replacement of a plurality of cabins can be completed, the use amount of gas cargoes is saved, and the conditions of environmental pollution and the like caused by outward discharge of cargo steam are avoided.

Description

Multi-cabin replacement system and method for gas ship

Technical Field

The application relates to the technical field of gas ship liquid cargo systems, in particular to a gas ship multi-cabin replacement system and method.

Background

Before a newly built gas ship such as an LPG or LNG ship is delivered to a shipside, a gas test is required to be carried out, the functions and safety of a liquid cargo treatment and fuel supply system, auxiliary key equipment and the like of the gas ship are verified, and the gas test is a final checkpoint for ensuring smooth delivery of the gas ship and is one of links with highest dangerous grade and highest cost in the construction process of the gas ship.

The gas test flow before sea test mainly comprises liquid cargo tank drying and inerting, replacement, cold tank, filling and the like, wherein the replacement flow is to replace nitrogen in the liquid cargo tank with cargo vapor such as LPG or LNG, the replacement flow is one of the operation flows of longest time consumption, longest cargo consumption such as LPG or LNG and the like and maximum cargo vapor emission into the environment in the gas test process, and if the cargo vapor and the nitrogen in the tank are not well layered in the replacement process, the stirring together of the cargo vapor is greatly increased.

At present, a plurality of cabins are connected in parallel at the same time for a conventional gas test scheme, replacement is carried out sequentially, and cold cabins and filling operation are carried out after replacement of each cabin is completed.

In view of the foregoing, there is a need to provide an improved solution to the above-mentioned deficiencies of the prior art.

Disclosure of Invention

The embodiment of the application aims to provide a multi-cabin replacement system and a multi-cabin replacement method for a gas ship, which can fully utilize cargo steam generated in the processes of front cabin replacement, cold cabin and filling to replace a rear cabin.

In a first aspect, there is provided a gas ship multi-pod replacement system comprising:

the plurality of cargo tanks sequentially comprise a fourth cargo tank, a third cargo tank, a second cargo tank and a first cargo tank along the direction from the stern to the bow;

A tank car for loading liquefied gas;

A filling pipe for connecting the tank wagon and the fourth cargo tank, wherein a gasification heater is arranged on the filling pipe and is used for heating liquefied gas into gas with a preset temperature, and the liquefied gas is injected into the bottom of the fourth cargo tank through the filling pipe;

the condensing pipe is arranged at the top of the fourth cargo tank and is used for connecting the fourth cargo tank with the tank car, and the condensing pipe is connected with the filling pipe in parallel; a nozzle is arranged at the joint of the condensing pipe and the fourth cargo tank, and the nozzle is used for spraying and cooling the fourth cargo tank;

an auxiliary filler pipe connected between the filler pipe and the condenser pipe;

The exhaust pipe is connected between two adjacent cargo tanks, one end of the exhaust pipe is an air inlet, the other end of the exhaust pipe is an air outlet, the air inlet is arranged at the top of the cargo tanks, and the air outlet extends into the bottom of the cargo tanks;

and the torch tower is connected to the top of the first cargo tank and is used for discharging tail gases such as nitrogen and burning cargo steam.

In one embodiment, the filling pipe arranged between the auxiliary filling pipe and the tank car is a first filling pipe, and the filling pipe arranged between the auxiliary filling pipe and the fourth cargo tank is a second filling pipe; the condenser pipe arranged between the auxiliary filling pipe and the tank car is a first condenser pipe, and the condenser pipe arranged between the auxiliary filling pipe and the fourth cargo tank is a second condenser pipe;

Opening the first filling pipe and the second filling pipe when a fourth cargo tank replacement is performed;

Opening the first condensation pipe and the second condensation pipe when the cold tank of the fourth cargo tank is performed;

when filling the fourth cargo tank, the first condenser pipe, the auxiliary filling pipe, and the second filling pipe are opened.

In one embodiment, the filler pipe is further used for discharging the cargo vapor at the bottom of the fourth liquid cargo compartment; cargo vapor is discharged upwards from the bottom of the filling pipe and flows back into the second condensing pipe through the auxiliary filling pipe so as to spray and cool the fourth cargo tank.

In one embodiment, the fourth cargo tank is connected to the third cargo tank via a first bleed line, the third cargo tank is connected to the second cargo tank via a second bleed line, the second cargo tank is connected to the first cargo tank via a third bleed line, and the first cargo tank is connected to the flare stack via a fourth bleed line.

According to a second aspect of the present application, there is also provided a gas ship multi-tank replacement method for performing gas ship multi-tank replacement using the gas ship multi-tank replacement system provided in the first aspect, comprising the steps of:

S1, before replacement, drying and inerting are completed in a plurality of liquid cargo tanks, and each liquid cargo tank is filled with nitrogen;

s2, opening a filling pipe, supplying liquefied gas to a gasification heater by a tank truck, injecting gas-phase cargoes treated by the gasification heater into the bottom of a fourth cargo tank, layering the gas-phase cargoes and nitrogen in the tank, and discharging the nitrogen in the fourth cargo tank to the bottom of a third cargo tank through a piston effect;

S3, when the volume content of the cargo vapor in the fourth liquid cargo tank is more than or equal to 95%, closing the filling pipe, opening the condensing pipe, and cooling the fourth liquid cargo tank through liquefied gas supplied by the tank wagon;

S4, replacing the third cargo tank by using cargo vapor generated during the cold tank operation of the fourth cargo tank; when the volume content of the cargo vapor in the third liquid cargo tank is more than or equal to 95%, the third liquid cargo tank finishes replacement;

S5, after the cold tank of the fourth cargo tank is completed, filling liquid cargo into the fourth cargo tank; and simultaneously completing the replacement of the second cargo tank and the first cargo tank.

In one embodiment, in step S2, samples are taken from the fourth cargo tank several times within a predetermined period of time, and the cargo vapor content of the fourth cargo tank at different points in time is measured to determine whether the replacement of the fourth cargo tank is completed.

In one implementation manner, in step S4, the following is further included: and acquiring the yield of the cargo steam generated by the fourth cargo tank in the cold tank process, judging whether the yield of the cargo steam can finish the replacement of the third cargo tank, and determining the spraying amount and the follow-up operation of the cold tank operation according to the judging result.

In one embodiment, the subsequent operations include at least:

When the temperature in the fourth cargo tank is cooled to-40 ℃, if the replacement operation of the third cargo tank is not completed, continuing to spray the fourth cargo tank until the replacement of the third cargo tank is completed; if the third cargo tank replacement has been completed, the nitrogen in the second cargo tank and in the first cargo tank is continued to be replaced with cargo vapor.

In one embodiment, in step S5, after the discharge of the cargo vapor generated during the filling process, the nitrogen gas is replaced continuously in the second cargo tank and in the first cargo tank.

In one embodiment, during the displacement, the tank pressures of the plurality of cargo tanks are sequentially reduced in the stern-to-bow sequence.

Compared with the prior art, the application has the beneficial effects that:

according to the technical scheme, the plurality of cargo tanks are connected in series through the exhaust pipe, cargo vapor generated in the processes of replacement of the front cargo tank, the cold cargo tank and filling is fully utilized to replace the rear cargo tank, so that the replacement of the cold cargo tank and the other cargo tanks is completed while liquid cargo is filled, no extra cargo is consumed, and the efficient utilization of the cargo vapor is realized; the tank wagon is connected with one cargo tank to replace a plurality of cabins, so that compared with the prior art, the tank wagon is required to be connected with the cargo tanks for replacement, gas cargoes used for gas tests are greatly saved, the situation that the gas is discharged to the atmosphere to pollute the environment is avoided, meanwhile, the gas test time is greatly saved, the gas test economy is improved, and popularization and use are facilitated.

Drawings

Fig. 1 is a schematic structural view of a multi-tank displacement system for a gas ship according to an embodiment of the present invention.

Fig. 2 is a schematic diagram showing replacement of a fourth cargo tank in the multi-tank replacement system for a gas ship according to the embodiment of the present invention.

Fig. 3 is a schematic diagram of a cold tank of a fourth cargo tank in a multi-tank replacement system for a gas ship according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of filling of a fourth cargo tank in a multi-tank displacement system for a gas ship according to an embodiment of the invention.

Fig. 5 is a flow chart of a multi-pod replacement method for a gas ship according to an embodiment of the present invention.

Wherein reference numerals are as follows:

1. A filling pipe; 11. a first fill tube; 12. a second filler tube; 2. a condensing tube; 21. a first condenser tube; 22. a second condenser tube; 31. a first exhaust pipe; 32. a second exhaust pipe; 33. a third exhaust pipe; 4. a tank car; 5. a flare stack; 6. an auxiliary filler pipe; CT1, a first cargo tank; CT2, a second cargo tank; CT3, a third cargo tank; CT4, a fourth cargo tank; CHV, gasification heater; v1, a first valve; v2, a second valve; v3, a third valve; v4, a fourth valve; v5, a fifth valve; v6, a sixth valve; v7, a seventh valve; v8, eighth valve.

Detailed Description

The following describes the embodiments of the present invention in further detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and are not intended to be limiting.

In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

Furthermore, in the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.

According to a first aspect of the present application, referring to fig. 1, there is provided a gas ship multi-tank displacement system, comprising: a plurality of cargo tanks (CargoTank, abbreviated as CT) that arrange in proper order along stern portion to fore direction specifically includes: fourth cargo tank CT4, third cargo tank CT3, second cargo tank CT2, and first cargo tank CT1.

A tank car 4, said tank car 4 being intended for loading liquefied natural gas (LiquefiedNaturalGas, abbreviated LNG) or liquefied petroleum gas (liquefiedpetroleumgas, abbreviated LPG), said tank car being connected to CT4 in this embodiment.

The filling pipe 1 is used for connecting the tank car 4 and the CT4, a gasification heater CHV (CargoHeater/Vaporizer, abbreviated as CHV) is arranged on the filling pipe 1 and used for heating and gasifying liquefied gas on the tank car into gas with preset temperature, namely, low-temperature liquefied gas is heated to normal-temperature gas, the temperature of the low-temperature liquefied gas is between minus 35 ℃ and minus 196 ℃, the temperature of the normal-temperature gas is between 10 ℃ and 30 ℃, the bottom of the CT4 is filled through the filling pipe 1, and the filling pipe 1 is also used for discharging cargo vapor at the bottom of a liquid cargo cabin.

The condensing pipe 2 is arranged at the top of the liquid cargo tank CT4 and is used for connecting the CT4 with the tank car, and the condensing pipe is connected with the filling pipe in parallel; and a nozzle is arranged at the joint of the condensing pipe and the CT4 and is used for spraying and cooling the CT4.

An auxiliary filling pipe 6 connected between the filling pipe 1 and the condenser pipe 2, wherein one end of the auxiliary filling pipe 6 is connected to the filling pipe 1 between the gasification heater CHV and the CT4, and the other end of the auxiliary filling pipe 6 is connected to the middle part of the condenser pipe 2; as shown in fig. 1 and 2, the filler pipe provided between the auxiliary filler pipe 6 and the tank car is a first filler pipe 11, and the filler pipe provided between the auxiliary filler pipe 6 and the CT4 is a second filler pipe 12; the condenser pipe provided between the auxiliary filling pipe 6 and the tank car is a first condenser pipe 21, and the condenser pipe provided between the auxiliary filling pipe 6 and the CT4 is a second condenser pipe 22.

At the time of CT4 replacement, the first filling tube 11 and the second filling tube 12 are opened. In the cold room of CT4, the first condenser tube 21 and the second condenser tube 22 are opened. At the time of filling of CT4, the first condenser tube 21, the auxiliary filling tube 6, and the second filling tube 12 are opened.

When the filling pipe 1 is used for discharging the cargo vapor at the bottom of the cargo tank, the cargo vapor is discharged through the second filling pipe 12 and then flows back into the second condensation pipe 22 through the auxiliary filling pipe 6, so as to spray-cool the fourth cargo tank.

The exhaust pipe 3 is connected between two adjacent cargo tanks, one end of the exhaust pipe is an air inlet, the other end of the exhaust pipe is an air outlet, the air inlet is connected to the top of the cargo tanks, and the air outlet extends into the bottom of the cargo tanks.

Specifically, CT4 and CT3 are connected through a first exhaust pipe 31, and a fifth valve V5 is disposed on the first exhaust pipe 31; CT3 and CT2 are connected through a second exhaust pipe 32, and a sixth valve V6 is arranged on the second exhaust pipe 32; CT2 and CT1 are connected to each other through a third exhaust pipe 33, and a seventh valve V7 is provided in the third exhaust pipe 33.

And the torch tower 5 is arranged at the top of the CT1, and the torch tower 5 is used for discharging tail gases such as nitrogen and the like and burning cargo steam. CT1 is connected with flare stack 5 through the fourth blast pipe, sets up eighth valve V8 on the fourth blast pipe. The fourth exhaust pipe is connected with a gas phase pipeline of the loading and unloading station and then connected with the flare stack 5.

Specifically, as shown in fig. 1, one end of the first exhaust pipe 31 is connected to the top of the CT4, and is used for discharging the low-density gas in the liquid cargo tank, and the other end of the first exhaust pipe 31 extends into the bottom of the CT 3.

In one embodiment, a first valve V1 is provided on the first filling pipe 11 between the vaporizing heater CHV and the tank vehicle, a second valve V2 is provided on the first condenser pipe 21, a fourth valve V4 is provided on the second condenser pipe 22, and a third valve V3 is provided on the auxiliary filling pipe 6.

According to a second aspect of the present application, as shown in fig. 1 to 5, there is also provided a multi-pod replacement method for a gas ship, using the multi-pod replacement system for a gas ship provided in the first aspect, comprising the steps of:

s1, before the liquid cargo tank is replaced, drying and inerting of the liquid cargo tank are completed, and the liquid cargo tank is filled with nitrogen.

Before step S1, a plurality of pipes are connected, and the purge and the tightness check work are completed.

S2, replacing nitrogen of one or two cargo tanks along a preset direction; nitrogen or mixed gas in the plurality of liquid cargo tanks is discharged to the flare stack 5 for release.

Specifically, the predetermined direction is a direction from the stern to the bow. Cryogenic liquefied gas is supplied through the tank car at a predetermined flow rate of 1.8-2.2t/h, and is connected to the liquid phase pipeline of the loading and unloading station on the ship through the filling pipe 1. The first valve V1, the fifth valve V5, the sixth valve V6, the seventh valve V7, and the eighth valve V8 are opened, and the vaporizing heater CHV. The tank car supplies liquid cargo with small flow, is connected to a liquid phase pipeline of a loading and unloading station on a ship through the filling pipe 1, is gasified and heated into normal-temperature gas-phase cargo through the gasification heater CHV after passing through the first valve V1, is injected into the CT4 cabin through the bottom filling pipe, the gas-phase cargo and nitrogen in the cabin form layering, the nitrogen in the cabin is replaced from the first exhaust pipe 31 through a piston effect, and the nitrogen in the cabin or nitrogen cargo vapor mixed gas is discharged to the CT3 through the first exhaust pipe 31 to replace the nitrogen in the CT3 continuously. CT4, CT3, CT2 and CT1 are connected in series in sequence, and the final tail gas is discharged to a flare stack 5 through an exhaust pipe 1 at the top of the CT1 cabin to be released.

It should be noted that, since the density ratio of liquefied gas cargo to gas cargo is 200:1, thus maintaining a low flow of injected liquefied gas cargo during the displacement process.

In one embodiment, as shown in fig. 2, in step S2, the replacing nitrogen in one or both cargo tanks includes at least the following:

and determining to replace CT4 or simultaneously completing the replacement of CT4 and CT3 according to the volumes of the liquid cargo tanks, the pressure to be maintained in the refrigerated rear cargo tank and the loaded cargo quantity.

And S21, calculating the vapor contents of the goods in the CT3, CT2 and CT1 cabins when the vapor content of the goods in the CT4 cabin reaches 100%.

And S22, calculating the vapor content of cargoes in the cabins CT3, CT2 and CT1 when the cold cabin of CT4 is completed.

And S23, calculating the vapor content of cargoes in the cabins CT3, CT2 and CT1 when the filling of the CT4 is completed.

S24, determining whether the content of the cargo steam in the CT1 cabin is more than or equal to 95%; when the content of the cargo vapor in the CT1 cabin is more than or equal to 95%, only CT4 is replaced. At a cargo vapor content of less than 95% in the CT1 compartment, CT4 and CT3 are replaced.

And S25, the sum of the steam content of the CT3 cargo when the replacement is completed and the steam content of the cargo in the CT1 cabin when the filling is completed is 100%.

In one embodiment, in step S2, during the replacement process, samples are taken from the up-sampling point, the middle-sampling point, and the down-sampling point in the CT4 cabin after a predetermined period of time, respectively, and the cargo vapor contents at different time points are measured to determine whether the replacement is completed.

And S3, when the content of the cargo vapor in the fourth liquid cargo compartment is more than or equal to 95%, closing the filling pipe 1, opening the condensing pipe 2, and cooling the CT4 by the liquefied gas supplied by the tank wagon 4.

Specifically, as shown in fig. 3, CT4 is cooled first, the first valve V1, the second valve V2 and the fourth valve V4 are closed, the flow of low-temperature liquefied gas is increased by the tank car 4, and the low-temperature liquefied gas is sprayed to cool CT4 after being atomized by the second valve V2 and the fourth valve V4 and the spray head at the tail part of the condensing tube.

And S4, replacing the subsequent cargo tanks by utilizing cargo vapor generated by the cold tank operation. When the volume content of the cargo vapor in the CT3 is more than or equal to 95%, the CT3 finishes replacement.

Because the temperature in the CT4 cabin is high, the low-temperature liquefied gas absorbs heat and gasifies rapidly in the cold cabin process, and a large amount of cargo vapor is generated, and the cargo vapor is injected into the bilge of the CT3 through the first exhaust pipe 31 and the fifth valve V5 to replace nitrogen in the CT3 cabin. Because the temperature of the evaporating gas is lower, the density is higher than that of the original normal-temperature nitrogen in the CT3 cabin, so that the evaporating gas is injected from the bottom of the CT3 cabin, the layering of the evaporating gas and the nitrogen is convenient, a piston effect is formed, and the replacement efficiency is improved.

In one implementation manner, in step S4, the following is further included: and acquiring the cargo vapor amount generated by the CT4 in the cold cabin process, judging whether the cargo vapor amount can complete the replacement of the CT3, and determining the cold cabin spraying amount and the follow-up operation according to the judging result.

When the cabin temperature of the CT4 is cooled to-40 ℃, if the replacement operation of the CT3 is not completed, namely the volume content of the cargo vapor in the CT3 is less than 95%, spraying the low Wen Yehuo to the CT4 cabin until the replacement of the CT3 cabin is completed. If the CT3 pod replacement has been completed, then the nitrogen in the CT2 and CT1 pods are continually replaced with cargo vapor.

Specifically, the method comprises the following steps:

S41, calculating the cargo vapor quantity q1 in the liquid cargo tank at the beginning of the cold tank according to the volume, the pressure and the temperature of the liquid cargo tank.

S42, calculating the cargo vapor quantity q2 in the liquid cargo tank when the cold cargo tank is completed according to the volume, the pressure and the temperature of the liquid cargo tank.

And S43, calculating the generation quantity qc=q2-q 1 of the cargo steam during cold room.

S44, the demand qg=1.7×tank volume of cargo vapor at the time of replacement is calculated.

S45, comparing the generation amount qc of the cargo steam during cold cabin and the demand amount qg of the cargo steam during replacement.

S46, when qc is larger than qg, CT2 is replaced continuously; and when qc is less than or equal to qg, continuously spraying low-temperature cargoes on to CT 4.

It should be noted that, for LPG gas ships, after CT4 completes the cold box operation, CT3 has completed the replacement, and the nitrogen of CT2 has also completed the partial replacement.

S5, after the cold cabin of the CT4 is completed, filling liquid goods into the CT4, and simultaneously completing the replacement of the CT2 and the CT 1.

Specifically, as shown in fig. 4, the fourth valve V4 is closed, the third valve V3 is opened, and the liquefied gas cargo in the tank car is filled into the CT4 through the second valve V2, the third valve V3, and the filling pipe. The cargo vapor generated in the filling process is discharged through the fifth valve V5 and the first exhaust pipe 31 to continuously perform nitrogen replacement on the CT2 and the CT1, so that the nitrogen replacement on the CT2 and the CT1 can be completed while the filling of the CT4 is performed. And cargo vapor generated in the filling process of the CT4 sequentially passes through the CT3, the CT2 and the CT1 to finish the replacement of nitrogen in the cabins of the CT2 and the CT1 until the volume content of the cargo vapor in the CT1 is more than or equal to 95 percent.

In the filling process, the liquid level of the CT4 and the cargo vapor volume concentration of the CT1 are obtained in real time, and the filling is stopped when the liquid level of the CT4 reaches a required value. At this time, if the cargo vapor volume concentration of CT1 is 95% or more, the replacement is completed; if the volume concentration of the cargo vapor of the CT1 is less than 95%, the nitrogen in the CT1 cabin is continuously replaced by the cargo vapor generated by slowly evaporating the liquefied gas in the CT4 cabin until the volume concentration of the cargo vapor reaches more than 95%.

In one embodiment, to prevent that some of the nitrogen in the CT1 compartment is not replaced when the filling of CT4 is completed, the total amount Q of cargo vapor produced during the filling of CT4 is calculated to determine the degree of replacement of both the CT4 and CT3 compartments during the initial replacement operation.

Specifically, step S5 further includes at least the following:

And S51, calculating the replaced cargo vapor quantity Q1 when the volume of the liquid cargo in the liquid cargo tank is increased in the filling process.

And S52, calculating the cargo vapor quantity Q2 generated when the liquid cargo tank insulating layer is cooled in the filling process.

And S53, calculating the vapor quantity Q3 of the goods generated after the external environment invades through the heat of the insulating layer in the filling process.

And S54, calculating the cargo vapor quantity Q4 generated after the heat of the cargo pipeline invades in the filling process.

And S55, calculating the cargo vapor quantity Q5 generated by flash evaporation caused by the pressure difference between the tank wagon and the cargo tank in the filling process.

And S56, determining the total cargo vapor generation quantity Q=Q1+Q2+Q3+Q4+Q5 in the filling process.

In one embodiment, during the displacement process, the plurality of cargo tanks are sequentially depressurized along the stern to the bow, so that cargo vapor can smoothly flow.

In summary, the plurality of cargo tanks are connected in series through the exhaust pipe, and cargo vapor generated in the processes of replacing the front cargo tank, the cold cargo tank and filling is fully utilized to replace the rear cargo tank, so that the replacement of the other cargo tanks is completed while the liquid cargo is filled in the cold cargo tank, and additional cargo is not required to be consumed, thereby realizing the efficient utilization of the cargo vapor; the tank wagon is connected with one cargo tank to replace a plurality of cabins, so that compared with the prior art, the tank wagon is required to be connected with the cargo tanks for replacement, gas cargoes used for gas tests are greatly saved, the situation that the gas is discharged to the atmosphere to pollute the environment is avoided, meanwhile, the gas test time is greatly saved, the gas test economy is improved, and popularization and use are facilitated.

The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and substitutions can be made by those skilled in the art without departing from the technical principles of the present invention, and these modifications and substitutions should also be considered as being within the scope of the present invention.

Claims

1. A gas boat multi-pod replacement system, comprising:

A tank car for loading liquefied gas;

the exhaust pipe is connected between two adjacent cargo tanks, one end of the exhaust pipe is an air inlet, the other end of the exhaust pipe is an air outlet, the air inlet is connected to the top of the cargo tanks, and the air outlet extends into the bottom of the cargo tanks;

2. A gas ship multi-tank replacement system according to claim 1, wherein a filler pipe provided between the auxiliary filler pipe and the tank car is a first filler pipe, and a filler pipe provided between the auxiliary filler pipe and the fourth cargo tank is a second filler pipe; the condenser pipe arranged between the auxiliary filling pipe and the tank car is a first condenser pipe, and the condenser pipe arranged between the auxiliary filling pipe and the fourth cargo tank is a second condenser pipe;

3. A gas ship multi-tank replacement system according to claim 2, wherein the filler pipe is further adapted to vent cargo vapors from the bottom of the fourth liquid cargo tank; cargo vapor is discharged upwards from the bottom of the filling pipe and flows back into the second condensing pipe through the auxiliary filling pipe so as to spray and cool the fourth cargo tank.

4. A gas ship multi-tank replacement system according to claim 3, wherein the fourth cargo tank is connected to the third cargo tank via a first vent pipe, the third cargo tank is connected to the second cargo tank via a second vent pipe, the second cargo tank is connected to the first cargo tank via a third vent pipe, and the first cargo tank is connected to the flare stack via a fourth vent pipe.

5. A gas ship multi-pod replacement method, characterized by performing a gas ship multi-pod replacement by a gas ship multi-pod replacement system according to any of claims 1 to 4, comprising the steps of:

s2, opening a filling pipe, supplying liquefied gas to a gasification heater by the tank truck, injecting gas-phase cargoes treated by the gasification heater into the bottom of a fourth cargo tank, layering the gas-phase cargoes and nitrogen in the tank, and discharging the nitrogen in the fourth cargo tank to the bottom of a third cargo tank through a piston effect;

s3, when the volume content of the cargo vapor in the fourth liquid cargo tank is more than or equal to 95%, closing the filling pipe, opening the condensing pipe, and cooling the fourth liquid cargo tank through the liquefied gas supplied by the tank wagon;

6. The gas ship multi-tank replacement method according to claim 5, wherein in step S2, the cargo vapor content of the fourth cargo tank is measured at different points in time by sampling from the fourth cargo tank a plurality of times within a predetermined period of time, respectively, to determine whether the replacement of the fourth cargo tank is completed.

7. The gas ship multi-tank replacement method according to claim 6, further comprising, in step S4: and acquiring the yield of the cargo steam generated by the fourth cargo tank in the cold tank process, judging whether the yield of the cargo steam can finish the replacement of the third cargo tank, and determining the spraying amount and the follow-up operation of the cold tank operation according to the judging result.

8. The gas ship multi-pod replacement method of claim 7, wherein the subsequent operations comprise at least:

9. The method according to claim 5, wherein in step S5, nitrogen gas substitution is continued for the second cargo tank and the first cargo tank after the discharge of the cargo vapor generated during the filling process.

10. The gas ship multi-tank replacement method according to claim 5, wherein the pressure in the tanks is sequentially reduced in the order of stern to bow during the replacement.