Energy-saving type LNG transport ship fuel gas supply system

Abstract

The utility model discloses an energy-saving type gas supply system for an LNG (liquefied natural gas) transport ship, which can meet the requirement of a dual-fuel engine on inlet gas temperature by cooling BOG (boil-off gas) gas subjected to primary compression and secondary compression by utilizing cold energy of the BOG from an LNG storage cabin, does not need to be provided with an intercooler, an aftercooler, a fresh water cooling pipe system and the like, and is energy-saving and environment-friendly. The system composition of the fuel gas supply system is greatly simplified, the initial investment cost is reduced, and the ship operation cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to shipbuilding technical field especially relates to an energy -conserving LNG transport ship gas supply system. BACKGROUND

[0002] On the LNG transport ship, LNG gas supply system needs to be configured. LNG gas supply system is usually composed of BOG compressor, intercooler, aftercooler, fresh water cooling system, etc. BOG from LNG storage cabin passes through primary compressor, intercooler, secondary compressor, aftercooler in turn, and then reaches dual fuel engine.

[0003] The existing LNG gas supply system mainly has the following deficiencies:

[0004] BOG temperature after primary compression of compressor is as high as about 110 DEG C, cannot satisfy secondary compressor inlet temperature requirement, needs to pass through intercooler cooling and then enters secondary compressor, BOG temperature after secondary compression of compressor is also as high as about 110 DEG C, cannot satisfy LNG dual fuel engine 0 DEG to 60 DEG C inlet temperature requirement, needs to pass through aftercooler cooling and then reaches dual fuel engine. Intercooler and aftercooler are cooled by fresh water, therefore need to configure fresh water cooling system including fresh water circulating pump, fresh water pipeline, etc., and fresh water system needs to be cooled by seawater, therefore still need to configure fresh water / seawater heat exchanger or need to increase fresh water / seawater heat exchanger capacity, gas supply system constitutes complexity, cost is high. SUMMARY

[0005] Therefore, the utility model provides an energy -conserving LNG transport ship gas supply system, this system does not need to set intercooler, aftercooler and fresh water cooling pipe system etc., utilizes the cold energy of BOG from LNG storage cabin and can cool the BOG gas after primary compression and secondary compression, greatly simplifies the system constitution of gas supply system, reduces initial investment cost, reduces ship operation cost.

[0006] An energy -conserving LNG transport ship gas supply system, including preheater, multistage compressor,

[0007] The cold side end inlet of the preheater is connected with the gas outlet of the LNG tank through a first gas conveying pipe, and the cold side end outlet is connected with the gas inlet of the first stage compressor of the multi-stage compressor through a second gas conveying pipe.

[0008] Preferably, a first regulating pipe is connected between the gas input pipe of the later stage compressor and the gas output pipe of the former stage compressor.

[0009] Preferably, a first regulating valve is arranged at the connection between the first regulating pipe and the gas output pipe of the former stage compressor.

[0010] Preferably, a second regulating pipe is connected between the gas output pipe of the last stage compressor and the third gas conveying pipe.

[0011] Preferably, a second regulating valve is arranged at the connection between the second regulating pipe and the gas output pipe of the last stage compressor.

[0012] Preferably, the gas inlet of the first stage compressor is further connected with a nitrogen conveying pipe.

[0013] Preferably, a breather pipe is further connected to the pipe section of the third gas conveying pipe close to the gas inlet of the dual-fuel engine, and a breather valve is arranged on the breather pipe.

[0014] Preferably, a first gas loop is connected between the gas input pipe of the later stage compressor and the gas input pipe of the former stage compressor, a second gas loop is connected between the pipe section of the third gas conveying pipe close to the gas inlet of the dual-fuel engine and the gas input pipe of the first stage compressor, and a control valve is arranged at the gas inlet of the dual-fuel engine.

[0015] The present application has the following advantages:

[0016] The present application can cool the BOG gas after one-stage compression and two-stage compression by using the cold energy of BOG from the LNG storage tank, so as to meet the gas inlet temperature requirement of the dual-fuel engine, without the need of setting an intermediate cooler, a post-cooler, a fresh water cooling pipe system and the like, greatly simplifying the system structure of the gas supply system, reducing the initial investment cost and the ship operation cost. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0018] Figure 1 is a structural schematic diagram of the present application.

[0019] The meanings of the reference numerals in the drawings are as follows:

[0020] 1 is a preheater, 2 is a first-stage compressor, 3 is a second-stage compressor, 4 is a dual-fuel engine, 5 is an LNG tank, 6 is a first gas delivery pipe, 7 is a second gas delivery pipe, 8 is a third gas delivery pipe, 9 is a first regulating pipe, 10 is a second regulating pipe, 11 is a first regulating valve, 12 is a second regulating valve, 13 is a nitrogen delivery pipe, 14 is a breather pipe, 15 is a breather valve, 16 is a first gas circuit, 17 is a second gas circuit, and 18 is a control valve. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be described below through specific embodiments shown in the drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0022] The terminology used in the present disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used in the present disclosure and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0023] It should be understood that, although the terms first, second, third, etc. can be employed in this disclosure to describe various information, these information should not be limited to these terms, and should not be understood as indicating or implying relative importance. These terms are only used to distinguish one type of information from another type of information. For example, without departing from the scope of the present disclosure, first information can also be referred to as second information, and similarly, second information can also be referred to as first information.

[0024] In the description of the utility model, unless otherwise specified and limited, it needs to be explained that the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be mechanical connection or electrical connection, it also can be the communication inside two elements, it can be direct connection, or it can be indirect connection through intermediate medium, for ordinary skilled person in the art, the specific meaning of the above terms can be understood according to specific circumstances.

[0025] In order to better understand the technical scheme of the utility model, the utility model is described in detail below in conjunction with the drawings.

[0026] The utility model provides a kind of energy-saving LNG transport ship gas supply system, including preheater 1, multistage compressor.

[0027] The cold side end import of the preheater 1 is connected with the gas outlet of LNG cabin 5 through first gas delivery pipe 6, and the cold side end export is connected with the gas import of the first stage compressor in multistage compressor through second gas delivery pipe 7, and multistage compressor is connected in series at the hot side end of preheater 1 to make the higher temperature gas formed after the compression of former stage compressor enter preheater 1 and exchange heat with the low-temperature gas of cold side end to become lower temperature gas, and the lower temperature gas continues to enter the compression of latter stage compressor, and the higher temperature gas formed after the compression of latter stage compressor enters preheater again and exchanges heat with the low-temperature gas of cold side end, until the higher temperature gas formed after the compression of last stage compressor exchanges heat in preheater 1 and is delivered to dual-fuel engine 4 through third gas delivery pipe 8, so that the low temperature (-140 ℃-100 ℃) of BOG gas flowing out from LNG cabin 5 can be used to cool the higher temperature BOG gas (the temperature of BOG gas compressed by compressor is about 110 ℃) after the compression of each stage compressor, so that the gas temperature entering dual-fuel engine 4 meets the air intake requirement of dual-fuel engine 4 (the air intake requirement of dual-fuel engine is 0 ℃-60 ℃).

[0028] Preferably, first regulating pipe 9 is connected between the gas input pipe of latter stage compressor and the gas output pipe of former stage compressor, first regulating valve 11 is arranged at the connection of first regulating pipe 9 and the gas output pipe of former stage compressor, or first regulating valve 11 is arranged on the pipeline of first regulating pipe 9, and the inlet temperature of latter stage compressor can be adjusted by adjusting the valve opening of first regulating valve 11, to prevent the inlet temperature of latter stage compressor being too high or too low.

[0029] Preferably, a second regulating pipe 10 is connected between the gas output pipe of the last stage compressor and the third gas delivery pipe 8, and a second regulating valve 12 is arranged at the connection between the second regulating pipe 10 and the gas output pipe of the last stage compressor, or arranged on the pipe of the second regulating pipe 10, and the valve opening of the second regulating valve 12 is adjusted to prevent the intake temperature of the dual-fuel engine 4 from being too high or too low.

[0030] Preferably, the gas inlet of the first stage compressor is further connected with a nitrogen delivery pipe 13, and a control valve is arranged on the nitrogen delivery pipe 13 to control the opening and closing of the pipe, and a gas permeation pipe 14 is further connected to the pipe section of the third gas delivery pipe 8 close to the intake of the dual-fuel engine 4, and a gas permeation valve 15 is arranged on the gas permeation pipe 14.

[0031] Preferably, a first gas loop 16 is connected between the gas input pipe of the last stage compressor and the gas input pipe of the previous stage compressor, and a second gas loop 17 is connected between the pipe section of the third gas delivery pipe 8 close to the intake of the dual-fuel engine 4 and the gas input pipe of the first stage compressor, and a control valve 18 is arranged at the intake of the dual-fuel engine 4.

[0032] In the embodiment, two stage compressors are arranged, i.e. a first stage compressor 2 and a second stage compressor 3, the cold side outlet of the preheater 1 is connected with the gas inlet of the first stage compressor 2 through a second gas delivery pipe 7, the gas outlet of the first stage compressor 2 is connected with one of the hot side inlets of the preheater 1 through a pipe, the corresponding hot side outlet of the preheater 1 is connected with the gas inlet of the second stage compressor 3 through a pipe, the gas outlet of the second stage compressor 3 is connected with the other hot side inlet of the preheater 1 through a pipe, and the corresponding hot side outlet of the preheater 1 is connected with the dual-fuel engine 4 through a third gas delivery pipe 8.

[0033] In actual use, the specific use steps of the energy-saving LNG transport ship gas supply system of the application are as follows:

[0034] First, the compressor is preheated by nitrogen delivered through the nitrogen delivery pipe 13:

[0035] Specifically, the first gas delivery pipe 6, the second gas delivery pipe 7, the third gas delivery pipe 8, the second regulating pipe 10, the gas permeation pipe 14 and the second gas circuit 17 are closed, the nitrogen delivery pipe 13, the first regulating pipe 9 and the first gas circuit 16 are opened, the valve 11 on the first regulating pipe 9 is a three-way valve in this embodiment, so that the first regulating pipe 9 is opened by closing the lower valve port of the first regulating valve 11 and opening the upper valve port and the right valve port, then the nitrogen in the nitrogen delivery pipe 13 is introduced, compressed by the primary compressor 2, and returned to the inlet of the primary compressor 2 through the first regulating pipe 9 and the first gas circuit 16 to be cyclically compressed, when the primary compressor 2 is preheated to meet the requirements, the first gas circuit 16 is closed, the second regulating pipe 10 and the second gas circuit 17 are opened, and the opening and closing states of the other pipes remain unchanged, the nitrogen in the nitrogen delivery pipe 13 is compressed by the primary compressor 2, enters the secondary compressor 2 through the first regulating pipe 9, is further compressed by the secondary compressor, and is returned to the inlet of the primary compressor 2 through the second regulating pipe 10 and the second gas circuit 17 to be cyclically compressed, until the secondary compressor 2 is preheated to meet the requirements;

[0036] When the secondary compressor 2 is preheated to meet the requirements, the lower valve ports of the first regulating valve 11 and the second regulating valve 12 are opened, and the right valve ports are opened, so that the first regulating pipe 9 and the second regulating pipe 10 are closed, the nitrogen delivery pipe 13 and the second gas circuit 17 are closed, the first gas delivery pipe 6, the second gas delivery pipe 7, the third gas delivery pipe 8 and the gas permeation pipe 14 are opened, and the control valve 18 remains closed, the BOG gas in the LNG tank enters the cold side end of the preheater 1 through the first gas delivery pipe 6, and the nitrogen remaining in the pipeline of the primary compressor 1 and the secondary compressor 2 enters the hot side end of the preheater 1, after heat exchange in the preheater 1, the remaining nitrogen is discharged through the third gas delivery pipe 8 and the gas permeation pipe 14,

[0037] When the remaining nitrogen is completely discharged, the gas permeation pipe 14 is closed, the control valve 8 is opened, the BOG gas in the LNG tank enters the cold side end of the preheater 1 through the first gas delivery pipe 6, and then enters the primary compressor 2 for compression through the second gas delivery pipe 7, the gas temperature is increased to about 110℃ after compression by the primary compressor, then the high-temperature BOG gas formed flows to the hot side end of the preheater 1 to exchange heat with the low-temperature BOG at the cold side end, the lower-temperature BOG gas formed after cooling is further compressed by the secondary compressor, the gas temperature is increased to about 110℃ again after compression by the secondary compressor, then the high-temperature BOG gas formed flows to the hot side end of the preheater 1 to exchange heat with the low-temperature BOG at the cold side end, the lower-temperature BOG gas formed after cooling is delivered to the dual-fuel engine 4 through the third gas delivery pipe 8;

[0038] When the primary compressor 2 and the secondary compressor 3 are normally compressed, if the temperature of the gas entering the secondary compressor 3 is low (less than a set value), the right valve port of the first regulating valve 11 can be slightly adjusted to increase the temperature of the gas entering the secondary compressor 3; if the temperature of the gas entering the dual-fuel engine 4 is low (less than a set value), the right valve port of the second regulating valve 12 can be slightly adjusted to increase the temperature of the gas entering the dual-fuel engine 4.

[0039] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

Claims

1. An energy-saving LNG carrier gas supply system, characterized in that, Includes preheaters and multi-stage compressors. The cold-side inlet of the preheater is connected to the gas outlet of the LNG compartment via a first gas delivery pipe, and the cold-side outlet is connected to the gas inlet of the first-stage compressor in the multi-stage compressor via a second gas delivery pipe. The multi-stage compressors are connected in series on the hot-side of the preheater so that the higher-temperature gas formed after compression by the previous stage compressor enters the preheater and exchanges heat with the low-temperature gas on the cold side to become a lower-temperature gas. The lower-temperature gas continues to enter the next stage compressor for further compression. The higher-temperature gas formed after compression by the next stage compressor enters the preheater again and exchanges heat with the low-temperature gas on the cold side until the higher-temperature gas formed after compression by the last stage compressor exchanges heat in the preheater and is then delivered to the dual-fuel engine via a third gas delivery pipe.

2. The energy-saving LNG carrier gas supply system according to claim 1, characterized in that, A first regulating pipe connects the gas inlet pipe of the subsequent compressor to the gas outlet pipe of the preceding compressor.

3. The energy-saving LNG carrier gas supply system according to claim 2, characterized in that, A first regulating valve is provided at the connection between the first regulating pipe and the gas output pipe of the preceding compressor, or a first regulating valve is provided on the pipeline of the first regulating pipe.

4. The energy-saving LNG carrier gas supply system according to claim 1, characterized in that, A second regulating pipe is connected between the gas output pipe of the final stage compressor and the third gas delivery pipe.

5. The energy-saving LNG carrier gas supply system according to claim 4, characterized in that, A second regulating valve is provided at the connection between the second regulating pipe and the gas output pipe of the final stage compressor, or a second regulating valve is provided on the pipeline of the second regulating pipe.

6. The energy-saving LNG carrier gas supply system according to claim 1, characterized in that, The gas inlet of the primary compressor is also connected to a nitrogen delivery pipe.

7. The energy-saving LNG carrier gas supply system according to claim 1, characterized in that, The section of the third gas delivery pipe near the dual-fuel engine air inlet is also connected to a vent pipe, on which a vent valve is installed.

8. The energy-saving LNG carrier gas supply system according to claim 1, characterized in that, A first gas circuit is connected between the gas input pipe of the subsequent compressor and the gas input pipe of the preceding compressor. A second gas circuit is connected between the section of the third gas delivery pipe near the air inlet of the dual-fuel engine and the gas input pipe of the first compressor. A control valve is installed at the air inlet of the dual-fuel engine.

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