KR20230060847A - Ventilation System for LNG Fueled Ship - Google Patents

Abstract

A ventilation system for a liquefied natural gas (LNG) fueled ship is disclosed. According to the present invention, in performing ventilation on a ship's fuel gas supply line equipped with multiple engines that can be driven using LNG as fuel and a gas valve unit installed on the fuel gas supply line, by configuring a system to circulate dried compressed air by pushing it with pressure instead of using a conventional ventilation fan, it is possible to supply stable circulating air without pressure drop, and it is effective in preventing corrosion inside a double pipe by completely preventing the generation of condensate without installing an electric heater.

Description

Ventilation System for LNG Fueled Ship {Ventilation System for LNG Fueled Ship}

The present invention relates to a ventilation system for an LNG fueled vessel, and more particularly, to a ventilation system for an LNG fueled vessel equipped with an ED type gas valve unit for controlling the flow rate and pressure of LNG supplied as engine fuel. It is about.

Recently, clean fuels such as liquefied natural gas (LNG), which have low content of sulfur oxides and nitrogen oxides, are in the limelight as an alternative to conventional fuel oil as an energy source for ships, and both fuel oil and natural gas can be used. A dual fuel engine has been developed and applied to ships.

In an LNG carrier (LNGC), which is already built for the purpose of transporting large amounts of LNG, a technology is applied to produce the propulsion power and power of the ship by supplying LNG stored in the cargo hold as fuel for the engine. Recently, air pollution regulations have been applied As the use of LNG fuel is gradually strengthened, the use of LNG fuel is gradually being applied to ships other than LNGC.

On the other hand, LNG fueled ships (LFS: LNG Fueled Ships) that use LNG as fuel use LNG fuel by forcibly vaporizing LNG or using BOG (Boil-Off Gas) naturally generated from LNG as engine fuel. A fuel gas supply line for supplying fuel gas from the tank to the engine must be provided.

This fuel gas supply line is a gas pipe through which fuel gas with a risk of explosion flows. When passing through an area classified as a gas safety zone such as an engine room, it is prepared for leakage of LNG. Therefore, it must be composed of a double pipe, and ventilation must be performed so that air exchange is performed 30 times per hour with respect to the space between the inner pipe and the outer pipe of the double pipe.

In addition, the IGF Code for safety standards related to LNG ships stipulates that outside air, not internal air of the engine room, should be brought in or air from the cargo area should be suctioned and used as air for ventilation of the double pipe.

However, when outside air is brought in for air circulation of the double pipe, since the double pipe is formed with a considerable length of about 70 m or more, it is a key whether smooth air exchange by a ventilation fan can be performed.

Meanwhile, a gas valve unit (GVU) for controlling pressure and flow rate of fuel gas is installed on a fuel gas supply line for supplying fuel gas from an LNG fuel tank to an engine. Such a gas valve unit is inevitably exposed to the risk of gas leakage at all times due to the nature of being composed of valve devices that handle gas.

According to the classification rules prescribed in consideration of this risk, the gas valve unit is provided in an enclosed type (encolsed type, also referred to as 'ED type') airtightly surrounded by a housing, so that periodic ventilation for the enclosed space is performed. When equipped in an open type (also called 'OD type') without a separate housing, it must be placed in a gas danger zone where ventilation is always performed.

Conventionally, when the gas valve unit is provided as an ED type, it is common that a ventilation line and a ventilation fan for performing ventilation of the gas valve unit are independently configured. This is because air balancing is difficult when the capacity of the ventilation fan is small.

However, the prior art as described above is subject to additional facilities or constraints due to the single configuration of the ventilation line and ventilation fan for performing ventilation of the gas valve unit.

Specifically, the prior art is a redundancy concept so that the other one can be operated when one of the fans for performing ventilation for the double pipe of the ED type gas valve unit and the fuel gas supply line fails. Therefore, two units must be installed per engine, and two gas detectors must be installed for each engine to detect gas leaks in the inner tube of the double tube. For example, when a ship is provided with two engines driven by using LNG as fuel, a total of four fans and four gas detectors are required.

In addition, in gas mode, in which the engine is operated using LNG as fuel, ventilation of the double pipe of the fuel gas supply line and gas valve unit corresponding to the engine must be performed. All engines of the ship are in gas mode. When the fan is operated as the number of engines, the number of fans corresponding to the number of engines must be simultaneously operated, and therefore, there is a problem in that power consumption due to simultaneous operation of many ventilation fans increases.

In addition, structurally, the double pipe is difficult to achieve smooth air balancing during air circulation by the ventilation fan, and since it reacts sensitively to pressure drop, air circulation through the double pipe is well achieved in the test operation stage after design. A number of unresolved problems arose.

In addition, conventionally, when humid outside air is suctioned as air for performing ventilation, condensate is generated and there is a risk of corrosion of the inside of the double pipe. To prevent this, an electric heater is installed on the line for suctioning outside air. There was an inconvenience of having to perform heat tracing of the line.

An object of the present invention, proposed to solve the above conventional problems, is a fuel gas supply line for supplying fuel gas to the engine and a ventilator of a gas valve unit installed on the fuel gas supply line to control the supply of fuel gas. In performing ventilation, instead of using a conventional ventilation fan, dried compressed air is used to press and circulate air with high dryness from the beginning, so that stable circulation air can be supplied without pressure drop, and electric heaters It is to provide a ventilation system for LNG fueled ships that can prevent corrosion inside the double pipe by completely preventing the generation of condensate without the installation of

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

According to one aspect of the present invention for achieving the above object, the engine is mounted in the engine room and can be driven using LNG as fuel; a fuel gas supply line in which a pipe for supplying fuel gas to the engine is a double pipe disposed inside the engine room; a gas valve unit installed on the fuel gas supply line to control the pressure and flow rate of the fuel gas supplied to the engine, provided in an ED type sealed with a housing and disposed in the engine room; an air supply line for suctioning external air and supplying it to the external pipe in order to ventilate the outer pipe of the fuel gas supply line and the gas valve unit; a compressed air supply unit installed on the air supply line and compressing and drying the air supplied to the external tube through the air supply line; And a vent line connected to the outer pipe to discharge the air inside the outer pipe to the outside, and using the pressure of the compressed air generated by the compressed air supply unit, the outer pipe of the fuel gas supply line and the gas A ventilation system for an LNG fueled ship may be provided, characterized in that the air inside the valve unit is pushed to the vent line side and circulated.

The compressed air supply unit may include a compressor for suctioning and compressing outside air or air in the cargo area; a compressed air storage for storing air compressed by the compressor; a dryer for receiving and drying the compressed air stored in the compressed air storage; and an air control valve installed at a rear end of the dryer to control the flow rate of the dried compressed air supplied to the external pipe.

The air control valve may adjust the flow rate of air by adjusting the valve flow coefficient (Cv) to a value capable of performing air exchange 30 times per hour inside the outer pipe of the fuel gas supply line.

The engine is provided in plurality, the fuel gas supply line and the vent line are provided in plurality to correspond to the plurality of engines, respectively, and the air supply line is branched into a plurality of lines, each of the fuel gas supply line It can be connected to the outer tube.

The plurality of vent lines are integrated into one integrated line to form a final line for discharging the air of the outer pipe of the plurality of fuel gas supply lines to the outside, and the fuel gas by analyzing the components of the air circulating on the integrated line. A pair of gas detectors may be installed to detect leaks of

On the other hand, according to another aspect of the present invention for achieving the above object, a fuel gas supply line composed of a double pipe among pipelines supplying fuel gas containing LNG to an engine and a gas installed on the fuel gas supply line In performing the ventilation of the valve unit, the air circulation inside the fuel gas supply line and the gas valve unit is the supply of external air through the air supply line connected to the external pipe of the fuel gas supply line and the external pipe. It is made by discharging existing air through a vent line connected to, but the air circulation is performed by pushing using the pressure of compressed air by a compressor instead of using a ventilation fan. LNG fuel, characterized in that A ship's ventilation system may be provided.

The compressed air may be supplied to the outer pipe after moisture is removed by drying.

The ventilation system of an LNG fueled ship according to the present invention is a method of circulating air by pushing air with a high dryness from the beginning using dried compressed air instead of a method using a conventional ventilation fan, without a pressure drop. It is possible to supply stable circulating air and completely prevents the generation of condensate without installing an electric heater, which has the effect of preventing corrosion inside the double pipe.

In addition, according to the present invention, since it is possible to delete the existing ventilation fan and there is no need to install a separate electric heater for condensate generation, the structure of the ventilation system is simplified and design flexibility is improved. As a result, it can contribute to greatly improving shipbuilding and productivity.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

1 is a view schematically showing a ventilation system for an LNG fuel ship according to the present invention.

In order to fully understand the present invention and the operational advantages of the present invention and the objects and effects achieved by the practice of the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Matters represented in the drawings accompanying this specification may be somewhat different from the form actually implemented as a schematic drawing to easily explain the embodiments of the present invention, and the size of each component shown in the drawings is for explanation. They may be exaggerated or reduced and are not meant to be of actual size.

In addition, terms used in this specification are only used to describe specific embodiments and are not intended to limit the present invention. For example, in the present specification, 'including' a certain component means that other components may be further included, rather than excluding other components unless otherwise stated.

In addition, it should be understood that saying that a component is 'connected' to another component includes a direct connection as well as an indirect connection, and another component may exist between the two components. Singular expressions may be interpreted as including plural expressions unless the context clearly dictates otherwise.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the accompanying drawings. Embodiments described below are provided so that those skilled in the art can easily understand the technical idea of the present invention, and the present invention is not limited thereto.

1 is a view schematically showing a ventilation system for an LNG fuel ship according to the present invention.

Referring to FIG. 1 , a ventilation system of an LNG fueled ship according to the present invention includes a plurality of engines 11 and 12 mounted in an engine room and driven by using LNG as fuel; fuel gas supply lines SL1 and SL2 for supplying LNG as fuel to the engines 11 and 12; Compressed air supply unit for supplying dried compressed air to the double pipe of the fuel gas supply line (SL1, SL2) in order to perform ventilation (air circulation) for the pipe composed of double pipe among the fuel gas supply lines (SL1, SL2) 100); and vent lines VL1 and VL2 connected to the outer tube of the double tube of the fuel gas supply lines SL1 and SL2 to discharge air inside the outer tube.

The plurality of engines 11 and 12 may include a propulsion engine (also referred to as 'main engine') that produces the propulsive power of the ship and a power generation engine that produces the necessary power in the ship, and MDO, HFO fuel oil and natural gas It can be provided as a dual fuel engine that can be driven by using both as fuel.

Preferably, the engines 11 and 12 of the present invention may be provided as a power generation engine that generates power by power generation and supplies it to various demand places in the ship, for example, DFGE (Dual Fuel GEnerator), DFDG (Dual Fuel Diesel Generator), DFDE (Dual Fuel Diesel Electric Engine) may be provided.

Hereinafter, the installation of a total of two engines 11 and 12 in a ship is described as a preferred embodiment, but the number of engines 11 and 12 is not limited or limited thereto, and the required load level of the ship It is natural that the logarithm can be increased or decreased according to .

An engine room in which a plurality of engines 11 and 12 are mounted may be partitioned at the stern of the LNG fuel ship according to the present invention. The engine room is a space classified as a gas safety zone, and safety from the gas danger zone must be secured. According to the classification rules, direct access from the gas dangerous area to the gas safe area is prohibited (air-lock installation if necessary), and the gas piping passing through the gas safe area must be composed of a double pipe or completely closed by a duct. do.

On the other hand, although not shown in the drawing, the LNG fueled ship according to the present invention has an LNG fuel tank for storing LNG to be used as fuel for the engines 11 and 12, and an LNG stored in the LNG fuel tank or inside the LNG fuel tank. A fuel gas supply system (FGSS) that properly processes naturally occurring BOG and supplies it as fuel to the engines 11 and 12 may be provided.

The LNG fuel tank may include an appropriate level of insulation and sealing system to accommodate LNG liquefied at a cryogenic temperature. An independent type tank that can be mounted independently can be used freely without restrictions on the type.

In order for the LNG stored in the LNG fuel tank to be used as fuel, it must meet the conditions such as pressure and temperature required by the engines 11 and 12, and for this purpose, the LNG or BOG extracted from the LNG fuel tank is delivered to the fuel gas supply system After being subjected to a series of treatments including compression and heating, it is supplied to the engines 11 and 12. When the LNG in the LNG fuel tank is directly extracted and used as fuel, a process of forcibly vaporizing the LNG may be further involved. In order to perform this treatment, the fuel gas supply system may include equipment such as a high-pressure pump (HP pump), a vaporizer (vaporizer), a compressor (compressor) and a heater (heater).

LNG fuel processed by the fuel gas supply system (hereinafter referred to as 'fuel gas') may be supplied to the engines 11 and 12 along the fuel gas supply lines SL1 and SL2. At this time, since the operating conditions of the plurality of engines 11 and 12 and the required fuel gas conditions may be different from each other, the fuel gas supply lines SL1 and SL2 are provided as a plurality of lines corresponding to the respective engines 11 and 12 Can be connected individually.

Specifically, a first fuel gas supply line (SL1) for supplying fuel gas from the fuel gas supply system to the first engine 11, and a second fuel gas supply line (SL1) for supplying fuel gas to the second engine 12 from the fuel gas supply system. Fuel gas supply lines SL2 are provided respectively.

Since the fuel gas supply lines SL1 and SL2 are gas pipes through which fuel gas with a risk of explosion flows, the fuel gas supply lines SL1 and SL2 disposed in the engine room classified as a gas safety zone are configured as double pipes. Referring to the drawing, it can be seen that the fuel gas supply lines SL1 and SL2 from the weather deck leading into the engine room to the engines 11 and 12 are composed of double pipes.

Gas valve units 21 and 22 may be installed on each fuel gas supply line SL1 and SL2 to control pressure and flow rate of fuel gas supplied to each engine 11 and 12 . Specifically, on the first fuel gas supply line (SL1), the first gas valve unit 21 for controlling the pressure and flow rate of the fuel gas supplied to the first engine 11, and the second fuel gas supply line (SL2) ), the second gas valve unit 22 for controlling the pressure and flow rate of the fuel gas supplied to the second engine 12 may be respectively installed.

The gas valve units 21 and 22 are a group of valves that control the pressure and flow rate of the fuel gas supplied to the engines 11 and 12, and the pressure of the fuel gas supplied to the engines 11 and 12 is controlled by the engine. It is a device that quickly controls according to the load and cuts off the supply of fuel gas quickly and reliably as needed.

These gas valve units 21 and 22 are devices for controlling the flow of fuel gas with a risk of explosion, and when located in a gas safety area, they are provided in an ED type sealed with a housing to perform periodic ventilation, , when it is to be equipped with an OD type, it must be placed in a gas dangerous area where ventilation is always performed.

However, when the engines 11 and 12 of the present invention are provided as power generation engines, the power generation engines are supplied with fuel gas at a relatively low pressure compared to the main engine, and the flow rate of fuel gas required according to the load is flexibly changed. Therefore, if the gas valve units 21 and 22 are disposed away from the engines 11 and 12, it is difficult to adequately cope with load fluctuations of the engines 11 and 12.

In consideration of the above characteristics, the present invention configures the gas valve units 21 and 22 as an 'ED type' that seals them with a housing and places them in an engine room so that they can be positioned close to the engines 11 and 12.

On the other hand, in the present invention, the fuel gas supply lines (SL1, SL2) and the gas valve units (21, 22) composed of double pipes flow or control the flow of fuel gas having a risk of explosion, and according to classification rules It is required that proper ventilation be performed.

In order to satisfy the classification rules, the present invention is a compressed air supply unit 100 for supplying dried compressed air to the outer tube of the fuel gas supply lines (SL1, SL2) composed of double pipes and fuel gas supply lines (SL1, SL2) Provide vent lines (VL1, VL2) for discharging air in the outer pipe, and double pipes and gas valves of the fuel gas supply lines (SL1, SL2) by using the pressure of the compressed air generated by the compressed air supply unit 100 The system is configured so that the air inside the units 21 and 22 is circulated. Existing air pushed and discharged by the dried compressed air supplied by the compressed air supply unit 100 may be discharged to the outside through the vent lines VL1 and VL2.

More specifically, the compressed air supply unit 100 is installed on the air supply line AL connected to the outer tubes of the fuel gas supply lines SL1 and SL2, and includes a compressor 110 for suctioning and compressing external air; a compressed air storage 120 for storing air compressed by the compressor 110; a dryer 130 that receives and dries the compressed air stored in the compressed air storage 120; And it may include an air control valve 140 for adjusting the flow rate of the dried compressed air.

Compressor 110 may suction external air and compress it to approximately 3 to 7 bar, more preferably 5 bar. At this time, outside air may be used in an open area, not in a gas dangerous area, and for example, outside air or air in a cargo area may be used. In the present invention, the compressor 110 may be provided as a VFD TYPE controlled by a variable frequency drive (VFD).

The compressed air storage 120 may serve as a kind of buffer tank for temporarily storing air compressed by the compressor 110 . A pressure sensor 121 may be installed inside the compressed air storage 120, and the operation of the compressor 110 may be linked and controlled with reference to a pressure value measured by the pressure sensor 121.

The compressed air stored in the compressed air storage 120 is supplied to the dryer 130 and is converted into air having a very high dryness by removing moisture and then supplied to the air control valve 140.

The air control valve 140 is a device for adjusting and supplying the flow rate of air according to the amount required for ventilation, adjusting the valve flow coefficient (Cv) and supplying it to the external pipes of the fuel gas supply lines (SL1, SL2) Regulates the air flow rate. The flow rate of air supplied through the air control valve 140 may be measured by pressure sensors 151 and 152 installed at the front and rear ends of the air control valve 140 .

The valve flow coefficient (Cv) of the air control valve 140 can be adjusted to perform air exchange 30 times per hour with respect to the internal volume of the double pipe of the fuel gas supply lines (SL1, SL2), specifically The value of the valve flow coefficient (Cv) of the air control valve 140 may be determined by the following equation. Normally, 70 m ³ /h of air can be supplied.

As described above, the air compressed and dried by the compressed air supply unit 100 may be supplied along the air supply line AL to the outer tube of the double pipe of the fuel gas supply lines SL1 and SL2. At this time, the air supply line AL is branched into two lines AL-1 and AL-2 and can be connected to the first and second engines 11 and 12, respectively, and supplied through the air supply line AL. Air may be supplied to the outer tubes of the fuel gas supply lines SL1 and SL2 through the inside of the engines 11 and 12 . A double pipe for supplying fuel gas is also configured inside the engines 11 and 12, and ventilation is performed together.

The vent lines (VL1, VL2) are for discharging the air in the outer pipe of the fuel gas supply lines (SL1, SL2) to the outside, and each fuel gas supply line (SL1, SL2) has a vent line (VL1, VL2) respectively can be connected Specifically, the first vent line VL1 to the outer pipe of the first fuel gas supply line SL1 and the second vent line VL2 to the outer pipe of the second fuel gas supply line SL2 may be respectively connected. .

As described above, since the circulation of air for ventilation in the present invention can be performed by the pressure of compressed air, a separate ventilation fan is not installed on the vent lines VL1 and VL2.

The first vent line VL1 and the second vent line VL2 may then be integrated into one integrated vent line VL3 to form a final line for discharging air to the outside, and on the integrated vent line VL3. A gas detector 50, a flame screen 71, a flow switch 72, and the like may be installed.

A total of two gas detectors 50 may be installed on the integrated vent line VL3, and detect leakage of fuel gas by analyzing components of air exchanged during ventilation. When leakage of fuel gas is detected, a gas trip of the engines 11 and 12 may be performed.

The flame screen 71 serves to prevent the flame from spreading to other places in the event of an explosion accident.

The flow switch 72 is a device for detecting whether the air flow is smooth, and can give a signal indicating that the gas mode operation of the engines 11 and 12 is possible when the air flow is smooth.

The ventilation system of the NG fuel ship according to the present invention described above is a method of circulating air by pushing air with a high dryness from the beginning using compressed air instead of using a conventional ventilation fan. , It is possible to supply stable circulating air without pressure drop, and it has the effect of preventing corrosion inside the double pipe by completely preventing the generation of condensate without installing an electric heater.

In the above, it has been described that the present invention is applied to a ship using LNG as fuel, but in addition to LNG, which is the most representative liquefied gas, the present invention includes LPG (Liquefied Petroleum Gas), LEG (Liquefied Ethane Gas), and liquefied ethylene gas (Liquefied Ethylene Gas). It can be applied to ships that use various liquefied gases as fuel, such as gas) and liquefied propylene gas, which can be liquefied at low temperatures to be stored and transported, and can be used as fuel for engines in a vaporized state.

In addition, in the present invention, 'ship' may be interpreted as a concept including all types of vessels using various liquefied gases as engine fuel. Representatively, ships with self-propelled power such as LNGC and LFS, as well as offshore structures floating on the sea such as LNG FPSO (Floating Production Storage Offloading) and LNG FSRU (Floating Storage Regasification Unit) are also suitable for the concept of the ship of the present invention. can be included

It is obvious to those skilled in the art that the present invention is not limited to the described embodiments, and that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, such modifications or variations should fall within the scope of the claims of the present invention.

11: first engine
12: second engine
21: first gas valve unit
22: second gas valve unit
50: gas detector
71: flame screen
72: flow switch
100: compressed air supply unit
110: compressor
120: compressed air storage
121: pressure sensor
130: dryer
140: air control valve
151, 152: pressure sensor
SL1: first fuel gas supply line
SL2: second fuel gas supply line
AL: air supply line
VL1: first vent line
VL2: second vent line
VL3: Integrated Vent Line

Claims (7)

An engine mounted in the engine room and capable of driving using LNG as fuel;
a fuel gas supply line in which a pipe for supplying fuel gas to the engine is a double pipe disposed inside the engine room;
a gas valve unit installed on the fuel gas supply line to control the pressure and flow rate of the fuel gas supplied to the engine, provided in an ED type sealed with a housing and disposed in the engine room;
an air supply line for suctioning external air and supplying it to the external pipe in order to ventilate the outer pipe of the fuel gas supply line and the gas valve unit;
a compressed air supply unit installed on the air supply line and compressing and drying the air supplied to the external tube through the air supply line; and
It includes a vent line connected to the outer tube to discharge the air inside the outer tube to the outside,
Characterized in that by using the pressure of the compressed air generated by the compressed air supply unit to push and circulate the air inside the outer pipe of the fuel gas supply line and the gas valve unit toward the vent line,
Ventilation system for LNG fueled ships. The method of claim 1,
The compressed air supply unit,
A compressor that suctions and compresses outside air or air in the cargo area;
a compressed air storage for storing air compressed by the compressor;
a dryer for receiving and drying the compressed air stored in the compressed air storage; and
An air control valve installed at the rear end of the dryer to control the flow rate of the dried compressed air supplied to the external pipe,
Ventilation system for LNG fueled ships. The method of claim 2,
Characterized in that the air control valve controls the flow rate of air by adjusting the valve flow coefficient (Cv) to a value capable of performing air exchange 30 times per hour inside the outer pipe of the fuel gas supply line,
Ventilation system for LNG fueled ships. The method of claim 2,
The engine is provided in plurality,
The fuel gas supply line and the vent line are provided in plurality to correspond to the plurality of engines, respectively,
Characterized in that the air supply line is branched into a plurality of lines and connected to the outer pipe of each fuel gas supply line,
Ventilation system for LNG fueled ships. The method of claim 4,
The plurality of vent lines are integrated into one integrated line to form a final line for discharging the air of the outer tube of the plurality of fuel gas supply lines to the outside,
Characterized in that a pair of gas detectors are installed on the integrated line to detect leakage of fuel gas by analyzing the components of circulated air.
Ventilation system for LNG fueled ships. In performing ventilation of a fuel gas supply line composed of a double pipe and a gas valve unit installed on the fuel gas supply line among piping lines for supplying fuel gas containing LNG to the engine,
Air circulation inside the fuel gas supply line and the gas valve unit is the supply of external air through an air supply line connected to the external pipe of the fuel gas supply line and the supply of existing air through a vent line connected to the external pipe. It is made by discharge, characterized in that the air circulation is made by pushing using the pressure of compressed air by a compressor instead of using a ventilation fan.
Ventilation system for LNG fueled ships. The method of claim 6,
Characterized in that the compressed air is supplied to the outer tube after moisture is removed by drying,
Ventilation system for LNG fueled ships.

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