KR20160137895A - Fuel gas supplying system in ships - Google Patents

Abstract

Disclosed is a fuel gas supplying system. The fuel gas supplying system according to an embodiment of the present invention includes: a storage tank accommodating a liquefied gas and a boil-off gas; a first fuel gas supply line which comprises a compression part pressurizing the boil-off gas of the storage tank, and supplies the boil-off gas pressurized by passing through the compression part to a first engine; a reliquefaction line being supplied with a part of the pressurized boil-off gas and then reliquefying the supplied part of the pressurized boil-off gas; and a second fuel gas supply line supplying the boil-off gas whose part is pressurized by the compression part to a second engine while being branched from a stop part of the compression part. The reliquefaction line includes: a cooling part cooling the pressurized boil-off gas; a first expansion valve decompressing the pressurized boil-off gas passing through the cooling part primarily; a first gas-liquid separating apparatus separating the boil-off gas in a gas-liquid mixed state by passing through the first expansion valve into a liquid component and a gas component containing a nitrogen component denser than the liquid component; and a boil-off gas circulation line supplying the gas component containing the nitrogen component of high density separated in the first gas-liquid separating apparatus to the second engine. The second fuel gas supply line and the boil-off circulation line can be prepared so that at least one of the partially pressurized boil-off gas and the gas component containing the nitrogen component of high density is consumed in the second engine as a fuel gas.

Description

[0001] FUEL GAS SUPPLYING SYSTEM IN SHIPS [0002]

The present invention relates to a fuel gas supply system, and more particularly, to a fuel gas supply system for a ship capable of efficiently using and managing fuel gas.

As IMO regulations on the emission of greenhouse gases and various air pollutants are strengthened, shipbuilding and marine industries are replacing the use of conventional oil and diesel oil with natural gas, which is a clean energy source, In many cases.

Natural gas is typically a liquefied natural gas (Liquefied Natural Gas), a colorless transparent cryogenic liquid with a volume reduced to 1/600 by cooling the natural gas to about -162 degrees Celsius for ease of storage and transportation. Management and operation.

Such liquefied natural gas is contained in a storage tank installed in an insulated manner on the hull and stored and transported. However, since it is virtually impossible to completely contain the liquefied natural gas, the external heat is continuously transferred to the inside of the storage tank, and the evaporated gas generated by naturally vaporizing the liquefied natural gas is accumulated in the storage tank . It is necessary to treat and remove the evaporated gas since the evaporated gas may increase the internal pressure of the storage tank and cause deformation and damage of the storage tank.

Conventionally, evaporation gas is flowed into a vent mast provided on the upper side of a storage tank, or a method of burning evaporation gas by using a GCU (Gas Combustion Unit) has been used. However, this is not desirable from the viewpoint of energy efficiency. Therefore, a method of re-liquefying the evaporation gas by supplying the evaporation gas with the liquefied natural gas or the fuel gas to the engine of the ship respectively, or using the re- .

Natural gas, on the other hand, is a mixture containing not only methane but also ethane, propane, butane, nitrogen and the like. The nitrogen boiling point is about -195.8 degrees Celsius, which is much lower than that of methane (boiling point -161.5 degrees) and ethane (boiling point-89 degrees Celsius).

Accordingly, the evaporation gas generated by naturally vaporizing in the storage tank contains a large amount of nitrogen component having a relatively low boiling point, which causes deterioration of the re-liquefaction efficiency of the evaporation gas, thereby affecting the utilization and treatment of the evaporation gas I am crazy.

In addition, when the evaporation gas is supplied to the engine of the ship as the fuel gas, the nitrogen component of the evaporation gas affects the decrease in the calorific value of the fuel gas, thereby improving the liquefaction efficiency of the evaporation gas and the calorific value of the fuel gas, It is necessary to plan for citation and management.

Korean Patent Publication No. 10-2010-0035223 (published on Apr. 05, 2010)

An embodiment of the present invention is to provide a fuel gas supply system capable of improving the re-liquefaction efficiency of evaporation gas.

An embodiment of the present invention seeks to provide a fuel gas supply system that can efficiently use and manage fuel gas.

An embodiment of the present invention is intended to provide a fuel gas supply system capable of effectively regulating and maintaining the calorific value of the fuel gas supplied to the engine.

The embodiment of the present invention is intended to provide a fuel gas supply system that can achieve efficient facility operation with a simple structure.

An embodiment of the present invention is to provide a fuel gas supply system capable of improving energy efficiency.

According to an aspect of the present invention, there is provided a gas turbine comprising a storage tank for storing a liquefied gas and an evaporated gas, a compression unit for compressing the evaporated gas of the storage tank, A fuel gas supply line, a re-liquefaction line for re-liquefying a portion of the pressurized evaporated gas, and a second fuel supplying portion for supplying an evaporative gas branched from the intermediate portion of the compressed portion and partially pressurized by the compressing portion to the second engine A first expansion valve for primarily depressurizing the pressurized evaporative gas that has passed through the cooling section, and a second expansion valve for first reducing the pressure of the pressurized evaporative gas passing through the cooling section, A first gas-liquid separator for separating the vaporized gas passing through the valve into the gas-liquid mixed state into a gas component containing a liquid component and a nitrogen component at a higher concentration than the liquid component And an evaporation gas circulation line for supplying the gas component containing the nitrogen component at a high concentration separated from the first gas-liquid separator to the second engine, wherein the second fuel gas supply line and the evaporation gas circulation line And the gas component containing the partially pressurized evaporated gas and the nitrogen component at the high concentration may be supplied to the second engine as fuel gas.

And a second expansion valve for separating the gas component and the liquid component from the evaporation gas in the vapor-liquid mixed state through the second expansion valve, wherein the second liquid- Liquid separator, an evaporation gas recovery line for supplying gas components separated from the second gas-liquid separator to the upstream side of the compression section on the storage tank or the first fuel gas supply line, and an evaporator for recovering the liquid separated from the second gas- And a liquefied gas recovery line for supplying the components to the storage tank.

The cooling unit may be provided with a heat exchanger for heat-exchanging the pressurized evaporative gas with at least one of evaporative gas at the upstream of the compression unit and gas components separated from the first gas-liquid separator.

The first expansion valve may reduce the pressure of the pressurized evaporative gas to a pressure condition corresponding to a fuel gas pressure condition required by the second engine or a pressure of the partially pressurized evaporative gas to be supplied to the first gas- have.

A first expansion valve for primarily reducing the evaporated gas that has passed through the cooling section and cooled; a second expansion valve for expanding the first expansion valve, A first gas-liquid separator for primarily separating the evaporated gas, which has passed through the first decompression passage, into a gas component containing a liquid component and a nitrogen component having a higher concentration than the liquid component, A second fuel gas supply line branched from the intermediate portion of the compression unit to supply an evaporated gas partially pressurized by the compression unit to the second engine, and a second fuel gas supply line branched from the intermediate portion of the compression unit, And a re-liquefaction line for re-liquefying a part of the gas component, wherein the re-liquefaction line supplies the gas component primarily separated by the first gas-liquid separator to the second engine Wherein the second fuel gas supply line and the evaporation gas circulation line include at least one of a partially pressurized evaporation gas and a gas component containing the nitrogen component at a high concentration to the second engine And may be provided and provided for consumption as gas.

The fuel gas supply system according to the embodiment of the present invention has the effect of improving the efficiency and performance of re-liquefaction of the evaporation gas.

The fuel gas supply system according to the embodiment of the present invention has the effect of efficiently utilizing and managing the fuel gas.

The fuel gas supply system according to the embodiment of the present invention has the effect of effectively controlling and maintaining the calorific value of the fuel gas.

The fuel gas supply system according to the embodiment of the present invention has an effect of improving the energy efficiency.

The fuel gas supply system according to the embodiment of the present invention has an effect of enabling efficient facility operation as a simple structure.

1 is a conceptual diagram showing a fuel gas supply system according to an embodiment of the present invention.
2 is a conceptual diagram showing a fuel gas supply system according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to fully convey the spirit of the present invention to a person having ordinary skill in the art to which the present invention belongs. The present invention is not limited to the embodiments shown herein but may be embodied in other forms. For the sake of clarity, the drawings are not drawn to scale, and the size of the elements may be slightly exaggerated to facilitate understanding.

1 is a conceptual diagram showing a fuel gas supply system 100 according to an embodiment of the present invention.

Referring to FIG. 1, a fuel gas supply system 100 according to an embodiment of the present invention includes a storage tank 110, a compression unit 121 for pressurizing the evaporation gas of the storage tank 110, A first fuel gas supply line 120 for supplying the pressurized evaporative gas to the first engine 121, a re-liquefaction line 130 for re-liquefying the pressurized evaporative gas, A second fuel gas supply line 140 for supplying a partially pressurized evaporated gas to the second engine, and a calorific value adjustment unit for measuring and controlling the calorific value of the fuel gas supplied to the second engine.

In the following examples, liquefied natural gas and evaporative gas generated therefrom are used as an example to help understand the present invention. However, the present invention is not limited thereto, and various liquefied gases such as liquefied ethane gas and liquefied hydrocarbon gas, The same technical idea should be understood in the same way.

The storage tank 110 is provided to receive or store the liquefied natural gas and the evaporative gas generated therefrom. The storage tank 110 may be provided with a membrane-type cargo hold that is heat-treated to minimize vaporization of liquefied natural gas due to external heat penetration. The storage tank 110 stores the liquefied natural gas and the evaporation gas in a stable manner until the liquefied natural gas is received from the production site of the natural gas, The power generation engine of the present invention can be used as a fuel gas.

Since the storage tank 110 is generally installed in a heat-treated state, it is practically difficult to shut off the intrusion of external heat completely. Therefore, there is an evaporative gas generated by naturally vaporizing the liquefied natural gas in the storage tank 110 do. Such evaporated gas raises the internal pressure of the storage tank 110, and there is a risk of deformation and explosion of the storage tank 110. Therefore, it is necessary to remove or treat the evaporated gas from the storage tank 110. [ The evaporated gas generated in the storage tank 110 may be used as the fuel gas of the engine by the first fuel gas supply line 120 or the second fuel gas supply line 140 as in the embodiment of the present invention, Liquefied by the liquefaction line 130 and re-supplied to the storage tank 110. In addition, although not shown in the drawing, the evaporation gas may be supplied or consumed by supplying a vent mast (not shown) provided at an upper portion of the storage tank 110.

The engine may be supplied with fuel gas such as liquefied natural gas and vaporized gas stored in the storage tank 110 to generate propulsive force of the ship or generate electric power for power generation such as internal equipment of the ship. The engine may include a first engine that generates an output by receiving a relatively high-pressure fuel gas, and a second engine that generates an output by receiving a relatively low-pressure fuel gas. For example, the first engine may be an ME-GI engine or an X-DF engine capable of generating an output with a relatively high-pressure fuel gas, and the second engine may include a DFDE An engine, or the like. However, the present invention is not limited thereto, and it should be equally understood that various numbers of engines and various kinds of engines are used.

The first fuel gas supply line 120 may be provided to pressurize the evaporation gas present in the storage tank 110 and supply the pressurized gas to the first engine and the refueling line 130. The first fuel gas supply line 120 has an inlet end connected to the interior of the storage tank 110 and an outlet end connected to the first engine via the first fuel gas supply line 120 . The first fuel gas supply line 120 is provided with a compression section 121 having a plurality of stages of compressors 121a so that the evaporation gas can be processed in accordance with the conditions required by the engine, A re-liquefaction line 130 to be described later may be branched from the first fuel gas supply line 120.

The compression unit 121 may include a compressor 121a for compressing the evaporated gas and a cooler 121b for cooling the heated evaporated gas while being compressed. In the case where the engine is composed of a plurality of engines having different pressure conditions, the second fuel gas supply line 140, which will be described later, branches from the intermediate portion of the compression section 121 to supply the partially pressurized evaporative gas to the second engine .

1, the compression unit 121 is composed of five compressors 121a and a cooler 121b. However, the compression unit 121 may have various numbers of compressors A compressor 121a and a cooler 121b. Further, a cooling unit 131 of a re-liquefaction line 130, which will be described later, may be installed on the upstream side of the compression unit 121 on the first fuel gas supply line 120, and a detailed description thereof will be given later.

The re-liquefaction line (130) is provided to pass through the compression section (121) of the first fuel gas supply line (120) and to supply a part of the pressurized evaporation gas to re-liquefy it.

The re-liquefaction line 130 includes a cooling section 131 for cooling the pressurized evaporated gas, a first expansion valve 132 for primarily depressurizing the pressurized evaporated gas that has passed through the cooling section 131, A first gas-liquid separator 133 for passing the gas component passed through the first gas-liquid separator 133 into a gas component and a liquid component, A circulation line 134, a second expansion valve 136 for secondarily reducing the liquid component separated by the first gas-liquid separator 133, and a second expansion valve 136 to supply a vapor- Liquid separator 137 and the second gas-liquid separator 137 to the storage tank 110 or the first fuel gas supply line 120. The first gas-liquid separator 137 and the second gas- Liquid 138 separated from the second gas-liquid separator 137 to the storage tank 110 A gas recovery line 139 may be included.

The cooling unit 131 is provided to cool the pressurized evaporative gas supplied to the refueling line 130. The cooling unit 131 supplies the pressurized evaporated gas to the evaporation gas at the upstream end of the compression unit 121 conveyed along the first fuel gas supply line 120 and the first vapor phase gas conveyed along the evaporation gas circulation line 134 And a heat exchanger for exchanging heat with gas components separated in the separator 133. Since the pressurized evaporated gas is pressurized by the compressing section 121 and the temperature and pressure are increased, the low-temperature evaporation gas before passing through the compression section 121 of the first fuel gas supply line 120, Temperature gas component supplied to the liquid refining line 130 by heat exchange with the low-temperature gas component transferred along the line 134, as shown in FIG. Since the cooling unit 131 is provided as a heat exchanger, it is possible to cool the pressurized evaporated gas even without using a separate cooling device, thereby avoiding unnecessary waste of the power source, simplifying the facility, and improving facility operation efficiency.

The first expansion valve 132 may be provided at a rear end of the cooling unit 131. [ The first expansion valve 132 is capable of realizing re-liquefaction by cooling and expanding by primarily depressurizing the pressurized evaporated gas that has passed through the cooling section 131. The first expansion valve 132 may be, for example, a Joule-Thomson valve. The first expansion valve 132 may reduce the pressurized evaporated gas passing through the cooling section 131 to a pressure level corresponding to the fuel gas pressure condition required by the second engine. A detailed description thereof will be described later.

The first gas-liquid separator 133 is provided to separate the gas component and the liquid component from the vaporized gas in the vapor-liquid mixed state through the first expansion valve 132 and primarily cooled and decompressed. While the pressurized evaporated gas passes through the first expansion valve 132, it is cooled and decompressed to be re-liquefied, but a flash gas may be generated during the depressurization process. Accordingly, the first gas-liquid separator 133 receives the evaporated gas that has passed through the first expansion valve 132 and is in a gas-liquid mixed state, separates the gas and liquid components to thereby ensure the reliability of the re-liquefaction process, The components can be handled separately.

On the other hand, natural gas is a mixture containing not only methane as the main component but also ethane, propane, butane, nitrogen and the like. Among them, the boiling point of nitrogen is about -195.8 degrees Celsius, which is much lower than that of methane (boiling point -161.5 degrees Celsius) and ethane (boiling point -89 degrees Celsius). Since the nitrogen component has a very low boiling point, the evaporation gas generated by naturally vaporizing the inside of the storage tank 110 is relatively vaporized first by the nitrogen component to contain a large amount of nitrogen component. Further, the nitrogen component There is a problem that the re-liquefaction efficiency of the evaporation gas is decreased as the concentration of the gas is increased.

Especially, when the evaporation gas is pressurized by the compression unit 121 and the compressed evaporation gas is cooled by the cooling unit 131 in order to re-liquefy the evaporation gas, the evaporation gas pressurized by the first expansion valve 132 is decompressed A gas component such as flash gas separated by the first gas-liquid separator 133 contains a nitrogen component having a low boiling point at a high concentration. When the gaseous component containing the nitrogen component at a high concentration is circulated again in the fuel gas system 100, not only the re-liquefaction efficiency of the evaporation gas is lowered, but also the compressor 121a of the compression section 121, There is a problem that a load is generated on the back of the compressor 121 or the installation of a high-compression compressor 121a is required, resulting in inefficiency of facility operation.

The evaporation gas circulation line 134 is provided to supply a gas component containing a high concentration nitrogen component to the second engine as fuel gas, which is separated from the first gas-liquid separator 133. As described above, a nitrogen component at a relatively high concentration is contained relative to the gas component generated in the process of decompressing the evaporated gas cooled and pressurized through the first expansion valve 132. The evaporation gas circulation line 134 supplies the gas component having a low re-liquefaction efficiency to the second engine and supplies the gas component to the second engine as fuel gas, thereby efficiently utilizing the fuel gas, So that the re-liquefaction efficiency of the liquid component containing the relatively low concentration nitrogen component can be increased.

The first expansion valve 132 may be provided to supply the pressurized evaporated gas passed through the cooling section 131 to the first gas-liquid separator 133 by reducing the pressure to a level corresponding to the pressure condition required by the second engine . As described above, the cooled evaporated gas that has passed through the cooling section 131 is primarily depressurized by the first expansion valve 132, and the evaporated gas that has passed through the first expansion valve 132 and becomes a vapor-liquid mixed state The gas component, which is supplied to the first gas-liquid separator 133 to be separated into the liquid component and the gas component, and which contains the separated high-concentration nitrogen component, is consumed as the fuel gas in the second engine along the evaporation gas circulation line 134 . At this time, the gaseous component containing the nitrogen component at a high concentration conveyed along the evaporation gas circulation line 134 is supplied to the second engine so that the second component can be stably consumed and utilized as the fuel gas. It is necessary to have a corresponding pressure level. The first expansion valve 132 sequentially passes through the compression section 121 of the first fuel gas supply line 120 and the cooling section 131 of the re-liquefaction line 130 to sequentially pressurize and cool the evaporated gas The evaporation gas circulation line 134 can be decompressed only to a level corresponding to the fuel gas pressure condition required by the second engine so that the gas component containing the nitrogen component at a high concentration separated from the first gas- Can be directly supplied to the second engine as the fuel gas.

The evaporation gas circulation line 134 is provided so as to pass through a cooling part 131 constituted by a heat exchanger. The cooling liquid of the pressurized evaporation gas flowing along the re-liquefaction line 130 is cooled using the cold component of the gas component containing the high concentration nitrogen component flowing along the evaporation gas circulation line 134, Temperature heat of the pressurized evaporation gas flowing along the evaporation gas circulation line 134 to the temperature of the gas component flowing along the evaporation gas circulation line 134 to a level corresponding to the temperature condition of the fuel gas required by the second engine.

The evaporation gas circulation line 134 is provided with a flow rate regulating valve 152 of a calorific value regulator to be described later so that the supply amount of the fuel gas transferred along the evaporation gas circulation line 134 can be adjusted, do.

The liquid component containing the low concentration nitrogen component separated by the first gas-liquid separator 133 is conveyed along the liquefied gas circulation line 135 and the second expansion valve 136, in which the liquefied gas circulation line 135 is provided, Lt; RTI ID = 0.0 > re-liquefied < / RTI > As described above, the liquefaction efficiency of the evaporation gas is improved as the nitrogen component of low concentration is contained. As the liquid component separated by the first gas-liquid separator 133 contains the nitrogen component of low concentration, the second expansion valve 136 ), The generation of gas components such as flash gas is reduced and the liquefaction efficiency can be improved. The second expansion valve 136 may comprise, for example, a Joule-Thomson valve and the second expansion valve 136 may be evacuated to a pressure level corresponding to the internal pressure of the storage tank 110 have.

The second gas-liquid separator 137 is provided to separate the gas component and the liquid component from the vaporized gas in the vapor-liquid mixed state through the second expansion valve 136 and then cooled and depressurized. Although the liquid component of the first gas-liquid separator 133, which is further depressurized by the second expansion valve 136, contains a low concentration of nitrogen component and is largely re-liquidized, not only a small amount of nitrogen component is present, Is practically impossible. Accordingly, the evaporated gas that has passed through the second expansion valve 136 and becomes in the vapor-liquid mixed state is separated into the gas component and the liquid component in the second gas-liquid separator 137 to improve the reliability of the re-liquefaction process, can do.

The evaporated gas recovery line 138 is connected to the second gas-liquid separator 137 and the second gas-liquid separator 137 so as to supply the separated gas components to the storage tank 110 or the first fuel gas supply line 120 by the second gas- And may be provided between the tank 110 or the second gas-liquid separator 137 and the first fuel gas supply line 120. 1, the evaporation gas recovery line 138 is shown to re-supply the gas component of the second gas-liquid separator 137 to the upstream side of the compression section 121 on the first fuel gas supply line 120. However, 2 gas-liquid separator 137 to the storage tank 110, or re-supplied to the first fuel gas supply line 120 and the storage tank 110 together.

The liquefied gas recovery line 139 may be provided between the second gas-liquid separator 137 and the storage tank 110 so as to re-supply the liquid component separated by the second gas-liquid separator 137 to the storage tank 110 . The liquefied gas recovery line 139 may be provided in such a manner that its inlet-side end communicates with the lower side of the second gas-liquid separator 137 and its outlet-side end communicates with the inside of the storage tank 110. The liquefied gas recovery line 139 may be provided with an on-off valve (not shown) for regulating the supply amount of the re-liquefied liquefied natural gas recovered to the storage tank 110.

The second fuel gas supply line 140 is branched from the intermediate portion of the compression unit 121 of the first fuel gas supply line 120 so as to supply the partially pressurized evaporative gas to the second engine. The second fuel gas supply line 140 is provided with an inlet side end connected to the intermediate portion of the compression portion 121 and an outlet side end joined to the evaporation gas circulation line 134 to be connected to the second engine .

Since the second engine generates the output by receiving the relatively low-pressure fuel gas, the second engine is branched from the intermediate portion of the compression unit 121 that compresses the evaporated gas, And can be supplied with the fuel gas along with the gas component containing the nitrogen component at a high concentration conveyed along the evaporation gas circulation line 134 described above. Although not shown in FIG. 1, when the supply amount of the fuel gas supplied through the second fuel gas supply line 140 and the evaporation gas circulation line 134 is larger than the supply amount of the fuel gas required by the second engine, And the outlet side end of the second fuel gas supply line 140 may be branched and connected together with the GCU.

The calorific value adjustment unit is provided to measure and adjust the calorific value of the fuel gas supplied to the second engine.

The heating value means the amount of heat released when the fuel gas of a unit mass is completely burned. Methane, butane, and propane in natural gas have a relatively high calorific value, which increases the calorific value of the fuel gas (the calorific value of methane is about 12,000 kcal / kg, the calorific value of butane is about 11,863 kcal / kg and the calorific value of propane is about 2,000 kcal / kg), whereas the calorific value of nitrogen is very low (calorific value of nitrogen: about 60 kcal / kg). The higher the absolute content or concentration of nitrogen component, the lower the total calorific value of the fuel gas. If the total calorific value of the fuel gas supplied to the engine is too low to meet the minimum calorific value required by the engine, it affects the output of the engine and causes an unnecessary load on the engine.

As described above, in order to raise the liquefaction efficiency of the re-liquefaction line 130, a liquid component containing a relatively low concentration nitrogen component separated by the first gas-liquid separator 133 is supplied to the second expansion valve 136 side , A gas component containing a relatively high concentration of nitrogen component is supplied to the second engine through the evaporation gas circulation line 134 and is supplied to the second engine by the high concentration nitrogen component flowing along the evaporation gas circulation line 134 There is a possibility that the calorific value of the supplied fuel gas becomes lower than the calorific value required by the second engine.

Referring to FIG. 1, the calorific value adjustment unit of the fuel gas supply system 100 according to an embodiment of the present invention includes a calorific value measuring device 150 for measuring or calculating the calorific value of the fuel gas supplied to the second engine, And flow control valves 151 and 152 installed in the supply line 140 and the evaporation gas circulation line 134, respectively.

The calorific value gauge 150 is connected to the first gas-liquid separator 133, which is supplied to the second engine through the second pressurized evaporative gas and the evaporative gas circulation line 134 supplied to the second engine through the second fuel gas supply line 140, ) Can be measured in real time. The calorific value gauge 150 transmits the calorific value information of the fuel gas measured by a display unit (not shown) such as a display to notify the occupant of the vessel, or transmits calorific value information of the measured fuel gas to a control unit The control unit can control the degree of opening and closing of the flow rate control valve, which will be described later, by comparing and analyzing the conditionally calorific value of the input second engine and the calorific value information of the fuel gas transmitted from the calorific value measuring device 150. [

In FIG. 1, the calorific value measuring device 150 is provided at the rear end of the point where the evaporative gas circulation line 134 on the second fuel gas supply line 140 joins to measure the calorific value of the fuel gas. However, If the calorific value of the supplied fuel gas can be measured, its position can be variously modified.

The flow control valves 151 and 152 may be installed in the second fuel gas supply line 140 and the evaporation gas circulation line 134, respectively. Each of the flow control valves 151 and 152 is manually or manually controlled by the operator on the basis of the calorific value information of the fuel gas measured by the calorific value measuring device 150 and the calorific value information of the second engine So that the calorific value of the fuel gas can be controlled.

For example, when the calorific value of the fuel gas measured by the calorific value measuring device 150 is smaller than the calorific value of the second engine, the flow regulating valve 151 provided in the second fuel gas supply line 140 is opened, The flow regulating valve 152 provided in the line 134 may be closed or partially closed to increase the calorific value of the fuel gas. When the calorific value of the fuel gas measured by the calorific value measuring device 150 is larger than the calorific value of the second engine, the nitrogen gas component in the fuel gas supply system 100 is preferentially consumed in the evaporative gas circulation line The flow control valve 152 installed in the second fuel gas supply line 140 may be closed or the flow control valve 151 provided in the second fuel gas supply line 140 may be completely closed or partially closed.

2 is a conceptual diagram showing a fuel gas supply system 100 according to another embodiment of the present invention. Referring to FIG. 2, the calorific value adjustment unit of the fuel gas supply system 100 according to another embodiment of the present invention includes a calorific value measuring device 150 for measuring or calculating the calorific value of the fuel gas supplied to the second engine, A second fuel gas supply line 140, an evaporation gas circulation line 134, a calorific value adjustment line 153, and a heat generation amount adjustment line 153, which collect gas components supplied along the first and second fuel gas supply lines 134 and 134 to the liquefied gas circulation line 135, The flow rate control valves 151, 152, and 154 may be provided.

The fuel gas supply system 100 according to another embodiment of the present invention will now be described with reference to the accompanying drawings. It is omitted.

The calorific value adjustment line 153 is provided so that the inlet side end is connected to the evaporation gas circulation line 134 and the outlet side end is connected to the front end of the second expansion valve 136 on the liquefied gas circulation line 135 . As described above, the gas component flowing along the evaporation gas circulation line 134 contains a nitrogen component at a high concentration, and thus the calorific value is lower than that of the partially pressurized evaporation gas flowing along the second fuel gas supply line 140. Accordingly, a part of the gas component flowing along the evaporation gas circulation line 134 can be recovered to the liquefied gas circulation line 135 side, thereby raising and regulating the total calorific value of the fuel gas supplied to the second engine. At the same time, the calorific value adjustment line 153 recovers a part of the gas component flowing through the evaporative gas circulation line 134 to the liquefied gas circulation line 135, so that the amount of the fuel gas The supply amount can be efficiently controlled.

The calorific value adjustment line 153 may be provided with a flow rate regulating valve 154 for regulating the supply amount of some gas components flowing along the calorific value adjustment line 153. The flow rate control valve 154 is manually or manually controlled by the operator on the basis of the calorific value information of the fuel gas measured by the calorific value measuring device 150 and the calorific value information of the second engine, It is possible to control the supply amount of a part of the gas component flowing along the line 153. On the other hand, although not shown in the drawings, the amount of fuel supplied to the second fuel gas supply line 140 or the second engine is controlled based on the fuel gas supply amount information measured by the flow rate sensing unit (not shown) The degree of opening and closing of the flow control valve 154 may be controlled.

The fuel gas supply system 100 according to an embodiment of the present invention having such a structure is configured such that a gas component containing a relatively high concentration nitrogen component generated during the process of reducing the pressurized evaporation gas for the liquefaction process of the evaporation gas Is used as the fuel gas in the second engine and a liquid component containing a relatively low concentration of nitrogen component is supplied to the re-liquefaction process, whereby the efficient consumption of the nitrogen component in the fuel gas supply system 100 and the efficient consumption of the fuel gas system 100 ), The efficiency of re-liquefaction of the evaporated gas and the re-liquefaction performance of the re-liquefaction line are improved by continuously reducing the total nitrogen content in the re-liquefaction line.

Further, by measuring and adjusting the calorific value of the fuel gas by the calorific value adjuster, it is possible to control the heating value of the fuel gas in accordance with the calorific value required by the engine, thereby effectively using and managing the fuel gas.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, You will understand. Accordingly, the true scope of the invention should be determined only by the appended claims.

100: fuel gas supply system 110: storage tank
120: first fuel gas supply line 121: compression unit
130: Re-liquefaction line 131: Cooling unit
132: first expansion valve 133: first gas-liquid separator
134: Evaporative gas circulation line 135: Liquefied gas circulation line
136: second expansion valve 137: second gas-liquid separator
138: Evaporative gas recovery line 139: Liquefied gas recovery line
140: second fuel gas supply line 150: calorimeter
151, 152, 154: Flow control valve
153: Calorific value adjustment line

Claims (5)

A storage tank for storing the liquefied gas and the evaporated gas;
A first fuel gas supply line provided with a compression unit for pressurizing the evaporation gas of the storage tank and supplying the pressurized evaporated gas to the first engine through the compression unit;
A re-liquefaction line for supplying a part of the pressurized evaporated gas and re-liquefying it; And
And a second fuel gas supply line branched from a middle portion of the compression section and supplying an evaporated gas partially pressurized by the compression section to the second engine,
The re-liquefaction line
A first expansion valve for primarily depressurizing the pressurized evaporated gas that has passed through the cooling section, and a second expansion valve for passing the evaporated gas in a gas-liquid mixed state through the first expansion valve to a liquid Liquid separator for separating the gas component into a gas component containing a nitrogen component at a higher concentration than the liquid component, and a second gas-liquid separator for separating the gas component containing the nitrogen component at a high concentration from the first gas- Gas circulation line,
Wherein the second fuel gas supply line and the evaporation gas circulation line are connected to each other by a fuel gas which is provided to consume at least any one of the partially pressurized evaporation gas and the gas component containing the nitrogen component as high- Supply system. The method according to claim 1,
The re-liquefaction line
A second gas-liquid separator for separating the vaporized gas passing through the second expansion valve into a gas component and a liquid component; a second gas- An evaporative gas recovery line for supplying a gas component separated by the second gas-liquid separator to the upstream side of the compression section on the storage tank or the first fuel gas supply line, and a second gas-liquid separator for separating the liquid component separated in the second gas- To the fuel gas supply line. 3. The method of claim 2,
The cooling unit
And a heat exchanger for heat-exchanging the pressurized evaporated gas with at least one of an evaporative gas at a front end of the compression unit and a gas component separated at the first gas-liquid separator. The method according to claim 1,
The first expansion valve
And pressurizes the pressurized evaporation gas under a pressure condition corresponding to a fuel gas pressure condition required by the second engine or a pressure of the partially pressurized evaporation gas to supply the pressurized evaporation gas to the first gas-liquid separator. A compression unit for pressurizing the evaporation gas of the storage tank;
A cooling unit for cooling the pressurized gas passing through the compression unit;
A first expansion valve that primarily reduces the evaporated gas that has passed through the cooling section and is cooled;
A first gas-liquid separator for primarily separating the vaporized gas passing through the first expansion valve and decompressed first into a gas component containing a liquid component and a nitrogen component at a higher concentration than the liquid component;
A first fuel gas supply line through which the evaporation gas of the storage tank is supplied to the first engine through the compression unit;
A second fuel gas supply line branched from a middle portion of the compression section and supplying an evaporative gas partially pressurized by the compression section to the second engine; And
And a re-liquefaction line for supplying a part of the pressurized evaporation gas to re-liquefy,
The re-liquefaction line
And an evaporative gas circulation line for supplying the gas component, which is firstly separated by the first gas-liquid separator, to the second engine,
Wherein the second fuel gas supply line and the evaporation gas circulation line are connected to each other by a fuel gas which is provided to consume at least any one of the partially pressurized evaporation gas and the gas component containing the nitrogen component as high- Supply system.

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