阅读说明：本技术 一种高可靠性双燃料船舶lng供气系统 (High-reliability LNG (liquefied Natural gas) supply system for dual-fuel ship ) 是由 武彦峰 林文胜 田雅洁 于 2018-08-10 设计创作，主要内容包括：本发明公开一种高可靠性双燃料船舶LNG供气系统,包括：两组独立的第一LNG供气管线和第二LNG供气管线通过管路连通后互为冗余备份；一控制模块,其连接所述第一LNG供气管线和第二LNG供气管线中的各设备及阀门,并采集所述各设备和阀门的工作数据；根据采集的数据判定各所述设备和阀门的工作状态并发出相应控制指令；当其中任一所述LNG供气管线异常时,所述控制模块发送控制指令控制另一LNG供气管线进行供气管线的切换,或当其中任一所述LNG供气管线核心设备异常时,所述控制模块发送控制指令进行核心设备的切换。本发明将大大提高整个LNG供气系统的可靠性和稳定性。(The invention discloses a high-reliability LNG gas supply system for a dual-fuel ship, which comprises: the two groups of independent first LNG gas supply pipelines and two groups of independent second LNG gas supply pipelines are communicated through pipelines and then are mutually redundant; the control module is connected with each device and valve in the first LNG gas supply pipeline and the second LNG gas supply pipeline and collects working data of each device and valve; judging the working state of each device and each valve according to the acquired data and sending out corresponding control instructions; when any one of the LNG gas supply pipelines is abnormal, the control module sends a control instruction to control the other LNG gas supply pipeline to switch the gas supply pipeline, or when any one of the LNG gas supply pipeline core equipment is abnormal, the control module sends a control instruction to switch the core equipment. The invention can greatly improve the reliability and stability of the whole LNG gas supply system.)

1. A high reliability dual fuel boats and ships LNG gas supply system which characterized in that includes:

the two groups of independent first LNG gas supply pipelines and two groups of independent second LNG gas supply pipelines are communicated through pipelines and then are mutually redundant;

the control module is connected with each device and valve in the first LNG gas supply pipeline and the second LNG gas supply pipeline and collects working data of each device and valve; judging the working state of each device and each valve according to the acquired data and sending out corresponding control instructions; when any one of the LNG gas supply pipelines is abnormal, the control module sends a control instruction to control the other LNG gas supply pipeline to switch the gas supply pipeline, or when any one of the LNG gas supply pipeline core equipment is abnormal, the control module sends a control instruction to switch the core equipment.

2. The high reliability dual-fuel ship LNG gas supply system of claim 1, wherein the high reliability dual-fuel ship LNG gas supply system comprises a first gas supply line, which specifically comprises a first LNG storage tank, a first booster pump, a first vaporizer, a first heater, a first water glycol heat exchange module, and a first surge tank; the first LNG storage tank is connected with the first booster pump through a first pipeline and a first valve, the first booster pump is connected with the first gasifier through a second pipeline and a second valve, the first gasifier is connected with the first heater through a pipeline and then connected with the first pressure stabilizing tank through a third pipeline and a third valve, and the first water glycol heat exchange module is connected with the first gasifier and the first heater through pipelines to form a loop;

the high-reliability dual-fuel ship LNG gas supply system further comprises a second gas supply pipeline, and the second gas supply pipeline specifically comprises a second LNG storage tank, a second booster pump, a second vaporizer, a second heater, a second water glycol heat exchange module and a second pressure stabilizing tank; the second LNG storage tank with link to each other through fourth pipeline and fourth valve between the second booster pump, the second booster pump with link to each other through fifth pipeline and fifth valve between the second vaporizer, the second vaporizer passes through the tube coupling rethread sixth pipeline and sixth valve are connected behind the second heater the second surge tank, second water ethylene glycol heat transfer module with first vaporizer with connect into the loop through the pipeline between the first heater.

3. The high reliability dual fuel marine LNG supply system of claim 2,

one end of a seventh pipeline is connected between the outlet of the first LNG storage tank and the first valve, the other end of the seventh pipeline is connected between the outlet of the second LNG storage tank and the fourth valve, and a seventh valve is arranged on the seventh pipeline;

one end of an eighth pipeline is connected to a second pipeline between the outlet of the first booster pump and the second valve; a fifth pipeline between the outlet of the second booster pump and the fifth valve is connected with the other end of an eighth pipeline, and the eighth pipeline is provided with an eighth valve;

when the first booster pump or the second booster pump is abnormal, the pipeline is switched by controlling the closing and opening of the valve through the control module, and the first booster pump or the second booster pump is used for replacement;

when the first LNG storage tank or the second LNG storage tank is abnormal, the pipeline is switched by controlling the closing and opening of the valve through the control module, and the intact second LNG storage tank or the intact first LNG storage tank is used for replacement;

when the first vaporizer, the first heater or the second vaporizer and the second heater are abnormal, the control module controls the valve to be closed and opened to switch the pipeline, and the pipeline is replaced by the second vaporizer, the second heater or the first vaporizer and the first heater which are intact.

4. The high reliability dual fuel marine LNG supply system of claim 3,

the first LNG storage tank is provided with a first inlet, the second LNG storage tank is provided with a first inlet, the two first inlets are communicated through a ninth pipeline, and the ninth pipeline is provided with a ninth valve and a tenth valve respectively;

a first inlet on the first LNG storage tank is connected with a first heater through a tenth pipeline and an eleventh valve; a first inlet on the second LNG storage tank is connected with a second heater through an eleventh pipeline and a twelfth valve;

when excessive BOG is generated in the first LNG storage tank and/or the second LNG storage tank, the control module controls the valve to be closed and opened to switch the pipeline, and the excess BOG in the first LNG storage tank and/or the second LNG storage tank is supplied to a user through the first heater or the second heater to maintain the pressure in the first LNG storage tank and/or the second LNG storage tank within a normal range.

5. The high reliability dual-fuel marine LNG gas supply system of claim 4, further comprising a BOG reliquefaction process module, an inlet of which is connected to the ninth pipeline between the ninth valve and the tenth valve through a pipeline and a valve; and the outlet of the BOG reliquefaction processing module is respectively connected with the first LNG storage tank and the second LNG storage tank through two pipelines, and the two pipelines are respectively provided with a valve.

6. The high reliability dual fuel marine LNG supply system of claim 4,

the first LNG storage tank is connected to a second pipeline between the outlet of the first booster pump and the second valve through a twelfth pipeline, and a thirteenth valve is arranged on the twelfth pipeline;

the second LNG storage tank is connected to a fifth pipeline between the outlet of the second booster pump and the fifth valve through a thirteenth pipeline, and a fourteenth valve is arranged on the thirteenth pipeline;

when the first LNG storage tank or the second LNG storage tank is abnormal, the pipeline is switched by controlling the closing and opening of the valve through the control module, so that the switching between the first LNG storage tank and the second LNG storage tank or the emergency transfer of LNG is realized.

7. The high reliability dual fuel vessel LNG gas supply system of claim 2, wherein the first surge tank and the second surge tank are the same surge tank; the first water glycol heat exchange module and the second water glycol heat exchange module are the same water glycol heat exchange module.

Technical Field

The invention relates to the field of ship manufacturing, in particular to a high-reliability LNG (liquefied natural gas) supply system for a dual-fuel ship.

Background

In recent years, global control of harmful gas emissions from ships has become more stringent, and the latest clear restriction measures of the International Maritime Organization (IMO) are: from 1/2020, global ship sulfur emissions must be below the 0.5% limit. It is a trend that ships use natural gas fuel to meet the requirements of sulfur emissions and other emission limits. However, the LNG fuel cannot completely replace the original fuel oil combustion mode in a short period of time, so that the international mainstream commercial ships will consider using the dual-fuel engine more and more in a long period of time in the future.

The LNG gas supply technology applied to the existing ships is mainly suitable for small and medium-sized ships, the storage tank is small in size, the engine is an engine which is transformed from an original fuel mode engine or is in a pure fuel mode, the reliability and the stability are general, and the requirement of stable and reliable gas supply of an international mainstream dual-fuel engine cannot be met. The main reasons are as follows: the current technology generally has only a single gas supply pipeline for realizing the flow of LNG gas supply. The low-temperature booster pump, the core low-temperature heat exchanger, the key low-temperature valve and the like in the LNG supply flow process are generally only in single configuration. Any problem occurs to the core equipment with the highest use frequency, the whole system is stopped, the function of the system is completely lost, and the ship cannot use fuel gas, so that the normal operation of the ship is influenced. The prior art does not have the capability of supplying air and finishing maintenance at the same time, and even if a tiny repairable fault occurs, due to the uniqueness of a system pipeline and equipment, the problem of sitting sight only exists or even continues to be enlarged unless the system is stopped, so that the problem of influencing the normal operation of the system is developed. Therefore, there are significant problems with the system reliability and stability of existing LNG supply systems.

Disclosure of Invention

In view of the above technical problems in the prior art, the applicant discloses a high-reliability LNG gas supply system for a dual-fuel ship, which aims to overcome the problem that the whole system cannot work when some equipment is in trouble due to a single configuration in the gas supply system.

In order to achieve the above object, the applicant adopts the following technical means:

a high reliability dual fuel ship LNG gas supply system includes: the two groups of independent first LNG gas supply pipelines and two groups of independent second LNG gas supply pipelines are communicated through pipelines and then are mutually redundant; the control module is connected with each device and valve in the first LNG gas supply pipeline and the second LNG gas supply pipeline and collects working data of each device and valve; judging the working state of each device and each valve according to the acquired data and sending out corresponding control instructions; when any one of the LNG gas supply pipelines is abnormal, the control module sends a control instruction to control the other LNG gas supply pipeline to switch the gas supply pipeline, or when any one of the LNG gas supply pipeline core equipment is abnormal, the control module sends a control instruction to switch the core equipment.

Preferably, the high-reliability dual-fuel ship LNG gas supply system includes a first gas supply line, which specifically includes a first LNG storage tank, a first booster pump, a first vaporizer, a first heater, a first water glycol heat exchange module, and a first surge tank; the first LNG storage tank is connected with the first booster pump through a first pipeline and a first valve, the first booster pump is connected with the first gasifier through a second pipeline and a second valve, the first gasifier is connected with the first heater through a pipeline and then connected with the first pressure stabilizing tank through a third pipeline and a third valve, and the first water glycol heat exchange module is connected with the first gasifier and the first heater through pipelines to form a loop; the high-reliability dual-fuel ship LNG gas supply system further comprises a second gas supply pipeline, and the second gas supply pipeline specifically comprises a second LNG storage tank, a second booster pump, a second vaporizer, a second heater, a second water glycol heat exchange module and a second pressure stabilizing tank; the second LNG storage tank with link to each other through fourth pipeline and fourth valve between the second booster pump, the second booster pump with link to each other through fifth pipeline and fifth valve between the second vaporizer, the second vaporizer passes through the tube coupling rethread sixth pipeline and sixth valve are connected behind the second heater the second surge tank, second water ethylene glycol heat transfer module with first vaporizer with connect into the loop through the pipeline between the first heater.

Preferably, one end of a seventh pipeline is connected between the outlet of the first LNG storage tank and the first valve, the other end of the seventh pipeline is connected between the outlet of the second LNG storage tank and the fourth valve, and a seventh valve is arranged on the seventh pipeline; one end of an eighth pipeline is connected to a second pipeline between the outlet of the first booster pump and the second valve; a fifth pipeline between the outlet of the second booster pump and the fifth valve is connected with the other end of an eighth pipeline, and the eighth pipeline is provided with an eighth valve; when the first booster pump or the second booster pump is abnormal, the pipeline is switched by controlling the closing and opening of the valve through the control module, and the first booster pump or the second booster pump is used for replacement; when the first LNG storage tank or the second LNG storage tank is abnormal, the pipeline is switched by controlling the closing and opening of the valve through the control module, and the intact second LNG storage tank or the intact first LNG storage tank is used for replacement; when the first vaporizer, the first heater or the second vaporizer and the second heater are abnormal, the control module controls the valve to be closed and opened to switch the pipeline, and the pipeline is replaced by the second vaporizer, the second heater or the first vaporizer and the first heater which are intact.

Preferably, a first inlet is arranged on the first LNG storage tank, a first inlet is arranged on the second LNG storage tank, the two first inlets are communicated through a ninth pipeline, and a ninth valve and a tenth valve are respectively arranged on the ninth pipeline; a first inlet on the first LNG storage tank is connected with a first heater through a tenth pipeline and an eleventh valve; a first inlet on the second LNG storage tank is connected with a second heater through an eleventh pipeline and a twelfth valve; when excessive BOG is generated in the first LNG storage tank and/or the second LNG storage tank, the control module controls the valve to be closed and opened to switch the pipeline, and the excess BOG in the first LNG storage tank and/or the second LNG storage tank is supplied to a user through the first heater or the second heater to maintain the pressure in the first LNG storage tank and/or the second LNG storage tank within a normal range.

Preferably, the BOG reliquefaction device further comprises a BOG reliquefaction processing module, wherein an inlet of the BOG reliquefaction processing module is connected to the ninth pipeline between the ninth valve and the tenth valve through a pipeline and a valve; and the outlet of the BOG reliquefaction processing module is respectively connected with the first LNG storage tank and the second LNG storage tank through two pipelines, and the two pipelines are respectively provided with a valve.

Preferably, the first LNG storage tank is connected to the second pipeline between the outlet of the first booster pump and the second valve through a twelfth pipeline, and a thirteenth valve is arranged on the twelfth pipeline; the second LNG storage tank is connected to a fifth pipeline between the outlet of the second booster pump and the fifth valve through a thirteenth pipeline, and a fourteenth valve is arranged on the thirteenth pipeline; when the first LNG storage tank or the second LNG storage tank is abnormal, the pipeline is switched by controlling the closing and opening of the valve through the control module, so that the switching between the first LNG storage tank and the second LNG storage tank or the emergency transfer of LNG is realized.

Preferably, the first surge tank and the second surge tank are the same surge tank; the first water glycol heat exchange module and the second water glycol heat exchange module are the same water glycol heat exchange module.

Due to the adoption of the technical means, the problem that when the LNG gas supply system works, the whole system loses gas supply capacity due to the fact that part of equipment fails is solved, and the problem that the LNG gas supply system only has a single gas supply pipeline and the reliability bottleneck of core equipment is solved; the LNG supply system is provided with fault tolerance and online maintenance possibility, and when tiny problems occur in individual equipment, the maintenance can be carried out through switching under the condition that the whole system is not shut down, so that the problems can be better solved, and the expansion is avoided. In conclusion, the reliability and stability of the whole LNG supply system can be greatly improved through the invention.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

FIG. 2 is a schematic view of a first gas supply line configuration according to an embodiment of the present application.

FIG. 3 is a schematic view of a second gas supply line configuration in accordance with an embodiment of the present application.

FIG. 4 is a schematic diagram illustrating the switching of the booster pump according to the present application.

Fig. 5 is a schematic diagram of switching of the heat exchange device in this embodiment.

Fig. 6 is a schematic diagram illustrating the switching of the BOG gas supply in the LNG storage tank in this embodiment.

Fig. 7 is a schematic diagram of a switching structure of an LNG storage tank in an embodiment of the present application.

Fig. 8 is a schematic diagram of an emergency transfer structure of a natural liquefied gas storage tank according to an embodiment of the present application.

Fig. 9 is a schematic view of a partial connection of the BOG reliquefaction module according to the present embodiment.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.

Fig. 1 is a schematic structural diagram of an embodiment of the present invention. The high reliability dual-fuel boats and ships LNG gas supply system in this embodiment includes: the LNG supply system comprises two independent groups of first LNG supply pipelines, second LNG supply pipelines and a control module.

The first LNG gas supply pipeline and the second LNG gas supply pipeline are communicated through a pipeline and then are mutually redundant; the control module is connected with each device and valve in the first LNG gas supply pipeline and the second LNG gas supply pipeline and collects working data of each device and valve; judging the working state of each device and each valve according to the acquired data and sending out corresponding control instructions; when any one of the LNG gas supply pipelines is abnormal, the control module sends a control instruction to control the other LNG gas supply pipeline to switch the gas supply pipeline, or when any one of the LNG gas supply pipelines is abnormal in core equipment, the control module sends a control instruction to switch the core equipment.

The technologies of collecting, judging, controlling and the like of each valve by the control module are the prior art, and are not the key points of the application, so redundant description is not needed here. The control module 700 actually collects the working data of the working modules (including the BOG reliquefaction module, the LNG storage tank, the booster pump, the vaporizer, the heater, the water glycol heat exchange module, and the surge tank) of the gas supply system in this application, which are not shown in fig. 1, but are not absent. Similarly, the technologies of collecting, determining, and controlling the working data of each working module by the control module 700 are the prior art, and redundant description is not repeated here.

As shown in fig. 1, the specific configuration of the present embodiment includes: BOG reliquefaction processing module, two LNG storage tanks, two booster pumps, two gasifiers, two heaters, a water ethylene glycol heat exchange module and a surge tank. The specific connection structure is as follows:

the first LNG gas supply line comprises: the system comprises a first LNG storage tank 201, a first booster pump 301, a first vaporizer 401, a first heater 403, a water glycol heat exchange module 500 and a surge tank 600, wherein the surge tank 600 directly supplies gas to downstream users. The first LNG storage tank 201 is connected with the first booster pump 301 through a first pipeline G1 and a first valve V1, the first booster pump 301 is connected with the first vaporizer 401 through a second pipeline G2 and a second valve V2, the first vaporizer 401 is connected with the first heater 403 through a pipeline and then connected with the surge tank 600 through a third pipeline G3 and a third valve V3, and the water glycol heat exchange module 500 is connected with the first vaporizer 401 and the first heater 403 through a pipeline to form a loop;

the second LNG gas supply line includes: a second LNG storage tank 202, a second booster pump 302, a second vaporizer 402, a second heater 404, a water glycol heat exchange module 500, and a surge tank 600. The second LNG storage tank 202 is connected to the second booster pump 302 through a fourth pipeline G4 and a fourth valve V4, the second booster pump 302 is connected to the second vaporizer 402 through a fifth pipeline G5 and a fifth valve V5, the second vaporizer 402 is connected to the second heater 404 through a pipeline and then connected to the surge tank 600 through a sixth pipeline G6 and a sixth valve V6, and the water glycol heat exchange module 500 is connected to the first vaporizer 402 and the first heater 404 through a pipeline to form a loop;

one end of a seventh pipeline G7 is connected between the outlet of the first LNG storage tank 201 and the first valve V1, the other end of the seventh pipeline G7 is connected between the outlet of the second LNG storage tank 202 and the fourth valve V4, and a seventh valve V7 is arranged on the seventh pipeline G7; one end of an eighth pipeline G8 is connected to a second pipeline G2 between the outlet of the first booster pump 301 and the second valve V2; a fifth pipeline G5 between the outlet of the second booster pump 302 and a fifth valve V5 is connected with the other end of an eighth pipeline G8, and an eighth valve V8 is arranged on an eighth pipeline G8;

the first LNG storage tank 201 is provided with a first inlet, the second LNG storage tank 202 is provided with a first inlet, the first inlets are communicated with each other through a ninth pipeline G9, and the ninth pipeline G9 is provided with a ninth valve V9 and a tenth valve V10, respectively. A first inlet on the first LNG storage tank 201 is connected to the first heater 403 through a tenth line G10 and an eleventh valve V11; a first inlet on the second LNG storage tank 202 is connected to the second heater 404 through an eleventh line G11 and a twelfth valve V12;

the first LNG storage tank 201 is connected to a second pipeline G2 between the outlet of the first booster pump 301 and the second valve V2 through a twelfth pipeline G12, and a thirteenth valve V13 is disposed on the twelfth pipeline G12;

the second LNG storage tank 202 is connected to a fifth pipeline G5 between the outlet of the second booster pump 302 and the fifth valve V5 through a thirteenth pipeline G13, and a fourteenth valve V14 is disposed on the thirteenth pipeline G13;

also included is a BOG reliquefaction process module 100, an inlet of the BOG reliquefaction process module 100 being connected to the ninth line G9 between the ninth valve V9 and the tenth valve V10 through a line and a fifteenth valve V15; the outlet of the BOG reliquefaction module 100 is connected to the first LNG tank 201 and the second LNG tank 202 through two pipelines, and the two pipelines are respectively provided with a valve V16 and a valve V17.

Referring to fig. 1, in this embodiment, a set of intermediate medium water ethylene glycol heat exchange module 500 and a set of surge tank 600 are configured for two sets of air supply pipelines, mainly because the water ethylene glycol heat exchange module is a normal temperature device, the difficulty and requirement of manufacturing the device are not high, and the possibility of occurrence of problems and failures is low. Also, the surge tank 600 is configured as a single set because of its low probability of problems and malfunctions.

The invention is provided with two LNG storage tanks, thereby not only effectively increasing the LNG storage capacity, but also facilitating the balance arrangement of the deck. Meanwhile, two sets of core equipment (booster pumps, heat exchangers, valves) and the like with the highest use frequency are redundantly configured in the system. Meanwhile, the invention also establishes a reasonable pipeline topological structure, and actually forms a system structure that two LNG supply pipelines are independent and can be backed up and redundant through effective pipeline connection.

The redundant system structure not only can be used for mutual backup between the two gas supply pipelines, but also can be used for mutual backup between the two LNG storage tanks, the two LNG booster pumps and the two sets of low-temperature heat exchangers. Failure of any single device is not sufficient to cause a loss of the actual gas supply capacity of the system. Meanwhile, the system is supplemented with other designs (a reliquefaction device and a pressure stabilizing tank) to improve the reliability and the stability of the gas supply system as much as possible, so that the LNG gas supply system provided by the invention really becomes a gas supply system which meets the high requirements of the international mainstream medium-large dual-fuel ship engine and has high reliability and stability capability.

The use of each switching pattern is described in detail below in conjunction with the figures.

Switching of system air supply pipeline

Referring to fig. 1 and 2, fig. 2 is a schematic view of a first gas supply line structure according to an embodiment of the present application.

During normal operation of the first gas supply line, valves V1, V2, and V3 are open, and the remaining valves are closed. The LNG is pressurized from the first LNG tank 201 to a desired pressure by the first booster pump 301, and is pumped to the first vaporizer 401 and the first heat exchanger 403, and the LNG reaches a desired supply gas temperature after passing through the first vaporizer 401 and the first heat exchanger 403, and then enters the surge tank 600.

Referring to fig. 1 and 3, fig. 3 is a schematic view of a second gas supply line structure according to an embodiment of the present application.

In normal operation of the second gas supply line, valves V4, V5, and V6 are open and the remaining valves are closed. The LNG is pressurized from the second LNG storage tank 202 to a desired pressure by the second booster pump 302, and pumped to the second vaporizer 402 and the second heat exchanger 404, and the LNG reaches a desired supply gas temperature after passing through the second vaporizer 402 and the second heat exchanger 404, and then enters the surge tank 600.

The two gas supply lines are redundant with each other. When a problem occurs with the first air supply line, a second air supply line may be used for replacement under the control of the control module 700.

(II) switching of system core devices

In normal operation of the first or second gas supply line, the seventh and eighth valves V7, V8 are closed.

(1) See fig. 1 and 4. FIG. 4 is a schematic diagram illustrating the switching of the booster pump according to the present application.

If the first air supply line supplies air normally, when the second air supply line is under the backup condition, only the first valve V1, the second valve V2 and the third valve V3 are opened, if the first booster pump 301 is abnormal, the control module monitors the abnormality of pressure and equipment information, an instruction is sent to close the first valve, the seventh valve V7 is opened, the eighth valve V8 and the fourth valve V4 are opened, the fifth valve V5 is kept in a closed state, the second booster pump 302 is connected into the actual air supply line to replace the first booster pump 301, at the moment, the whole air supply system can still continue to work normally, the disconnected first booster pump 301 does not influence the system any more, and the system can be overhauled in time. Conversely, the replacement of the second booster pump 302 with the first booster pump 301 may be accomplished.

(2) Referring to fig. 1 and 5, fig. 5 is a schematic diagram of switching of the heat exchange device in the present embodiment.

If the first air supply line is supplying air normally, the second air supply line is in a standby condition. If the first gasifier 401 and the first heater 403 have problems or faults, the control module monitors the abnormality of pressure, temperature and equipment information, and sends out instructions to close the second valve V2 and the third valve V3 and open the eighth valve V8, the fifth valve V5 and the sixth valve V6, so that the second gasifier 402 and the second heater 404 are connected to an actual gas supply line to replace the first gasifier 401 and the first heater 403, the system can still keep normal operation at this time, the disconnected first gasifier 401 and the disconnected first heater 403 do not affect the system any more, and the system can be overhauled in time. Conversely, the replacement of the second vaporizer 402 and the second heater 404 may also be accomplished with the first vaporizer 401 and the first heater 403.

(3) Referring to fig. 1 and 6, fig. 6 is a schematic diagram illustrating the switching of the BOG gas supply in the LNG storage tank according to the present embodiment.

When the LNG is stored in the first LNG tank 201 for a long time and more BOG is generated, the BOG may be supplied to the user through the first heater 403 by opening the eleventh valve V11 through the tenth pipe G10, or may be supplied to the user through the second heater 404 by opening the ninth valve V9 and the tenth valve V10 through the ninth pipe G9.

Similarly, when the LNG is stored in the second LNG tank 202 for a long time and a large amount of BOG is generated, the BOG may be supplied to the user through the second heater 404 by opening the twelfth valve V12 through the eleventh pipe G11, or may be supplied to the user through the first heater 403 by opening the tenth valve V10 and the ninth valve V9 through the ninth pipe G9. The control module 700 may make the selection based on the actual operating air supply line. The BOG is supplied to a user for combustion, so that the pressure in the storage tank can be effectively reduced, the pressure is always in a normal allowable range, and the reliability of the system is improved.

(III) LNG tank switching and LNG emergency transfer

(1) See fig. 1 and 7. Fig. 7 is a schematic diagram of a switching structure of an LNG storage tank in an embodiment of the present application.

The first LNG storage tank 201 may be sequentially supplied with gas through the seventh pipeline to the second gas supply line by closing the first valve V1, and opening the seventh valve V7 and the fourth valve V4; likewise, the second LNG storage tank 202 may be sequentially supplied to the first gas supply line through the seventh pipeline by closing the fourth valve V4 and opening the seventh valve V7 and the first valve V1.

Even the LNG storage tank breaks down, also can in time empty the isolation with problem LNG storage tank through a series of urgent transfer processing, utilize another LNG storage tank to continue to store the LNG that shifts, realize the function of continuing the gas feed, avoid appearing the influence that the problem probably caused by the LNG storage tank.

(2) See fig. 1 and 8. Fig. 8 is a schematic diagram of an emergency transfer structure of an LNG storage tank in an embodiment of the present application.

When one LNG storage tank fails or the pressure may exceed an allowable value, and the LNG in the LNG storage tank needs to be transferred to another LNG storage tank in an emergency, a loop for transferring LNG between the first LNG storage tank 201 and the second LNG storage tank 202 may be formed by opening or closing related valves, and the operations are as follows: when it is desired to transfer LNG from the first LNG tank 201 to the second LNG tank 202, the first valve V1 is kept closed, the seventh valve V7, the fourth valve V4, and the fourteenth valve V14 are opened, and LNG is transferred to the second LNG tank 202 by the second booster pump 302. When it is required to transfer LNG from the second LNG tank 202 to the first LNG tank 201, as shown in fig. 1, the fourth valve V4 is kept closed, and the seventh valve V7, the first valve V1, and the thirteenth valve V13 are opened, and LNG is transferred to the first LNG tank 201 by the first booster pump 301.

A new gas supply pipeline is formed by controlling a corresponding valve or the emergency transfer of the LNG is completed, so that the reliability and the safety of the system are greatly improved.

Referring to fig. 1 and 9 again, fig. 9 is a schematic view of a partial connection of the BOG reliquefaction module in this embodiment.

In order to improve the reliability of the gas supply system, the BOG reliquefaction processing module 100 is also configured in the invention, and BOG reliquefaction can be recovered to the LNG storage tank for storage again. When the first LNG storage tank 201 has a large amount of BOG, the ninth valve V9 and the fifteenth valve V15 may be opened to allow the BOG to enter the BOG reliquefaction processing module 100; when the amount of BOG in the second LNG storage tank 202 is large, the tenth valve V10 and the fifteenth valve V15 may be opened to allow the BOG to enter the BOG reliquefaction processing module 100; the BOG reliquefaction processing module 100 may also process BOG in the first LNG storage tank 201 and the second LNG storage tank 202 at the same time, so as to ensure that the pressure in the LNG storage tanks is always within a normal allowable range. The reliquefied LNG is returned to the first LNG tank 201 through the valve V16 or to the second LNG tank 202 through the valve V17, and is flexibly selectable. The design of the BOG reliquefaction process module 100 can fundamentally ensure the reliability of the system for long-term storage of LNG.

The surge tank 600 is connected to a user (901, 902.. 90n) of the LNG supply system, and the gas is supplied to the user in a relatively stable state due to the stabilization of the surge tank. When a large-scale user such as a dual-fuel ship engine and the like starts an operation stage, the pressure of a pipeline also changes obviously due to the change of the flow in an air supply pipeline; in addition, when the working conditions of users such as an engine and the like change, the air consumption changes along with the change, and pipeline pressure fluctuation can also be caused. Based on these circumstances, in order to improve the stability of the system, the surge tank 600 is provided in the present invention.

The above-described embodiments are merely illustrative of the present invention and are not intended to limit the scope of the present invention. All equivalent changes and modifications of the invention that may occur to those skilled in the art are intended to be covered by the appended claims.