KR20100061368A - A fuel gas supply system and ship with the same - Google Patents

Abstract

PURPOSE: A fuel gas supply system and a ship with the same are provided to simplify the structure of a ship by removing a front cooler for cooling evaporated gas before the evaporated gas flows from an LNG storage tank to the compressor. CONSTITUTION: A fuel gas supply system and a ship with the same comprise a compressor(30), a cooler(90), and a supply conduit(42). The compressor compresses the evaporated gas vaporized from an LNG(Liquified Natural Gas) storage tank(10) inside. The cooler installed on the lower part of the compressor cools the compressed evaporated gas. The supply conduit supplies the evaporated gas frozen by cooler to a DFDE engine(60). The amount of the evaporated gas flowing into the compressor is the same with the amount of the evaporated gas discharged from the LNG storage tank. The compressor is a multiple-stage compressor.

Description

FUEL GAS SUPPLY SYSTEM AND SHIP WITH THE SAME}

The present invention relates to a fuel gas supply system and a ship having the same, and more particularly, to a fuel gas supply system and a ship having the same for supplying vaporized gas to the dual fuel engine.

In general, liquefied natural gas (LNG) refers to a colorless, transparent cryogenic liquid whose natural gas, which contains methane as its main component, is cooled to -162 ° C and its volume is reduced to one hundredth.

As this LNG is used as an energy resource, an efficient transportation method for transporting a large amount from the production base to the destination of the demand site has been considered in order to use this gas as energy. LNG carriers have been developed for transport.

Since the storage tank of the LNG carrier in which LNG is stored during transportation of LNG receives heat from the outside continuously, the LNG in the storage tank is continuously vaporized. This vaporization gas is called a boil-off gas (BOG). When the vaporized gas accumulates in the storage tank and the pressure in the storage tank is increased, the risk of damage to the storage tank increases. Therefore, the vaporized gas is used as fuel for propelling the ship, or liquefied and returned to the storage tank.

At this time, the propulsion of the vessel by using the vaporized gas is to burn the vaporized gas in the main boiler to generate steam, and then to drive the steam turbine using the generated steam, or alternate oil and gas as needed This is achieved by using fuel as a dual fuel engine (DFDE) that can be used as fuel.

Recently, due to environmental problems, studies on such dual fuel engines are being actively conducted, and many methods have been proposed for a device for supplying gas to the engine.

In a conventional fuel gas supply system, natural vaporized gas generated in a storage tank is injected with LNG by a pre-cooler, cooled to a required temperature by a cryogenic compressor, and then sent to a mist separator to remove mist.

The mist-free vaporized gas is compressed to the pressure required by the dual fuel engine in the cryogenic compressor, and cooled or heated to the temperature required by the dual fuel engine in the rear cooler or heater and sent to the dual fuel engine.

In addition, when a larger amount of fuel gas is required than a gaseous gas naturally occurring in the dual fuel engine, the forced evaporator forcibly evaporates the liquefied gas.

At this time, when using a forced evaporator, the pump in the storage tank is driven to supply LNG in the tank to the forced evaporator. The gas produced by passing LNG through a forced evaporator is fed to a dual fuel engine via natural coolant gas, through a front cooler, a mist separator and a cryogenic compressor, and then through a rear cooler or heater.

Since the conventional fuel gas supply system uses a cryogenic compressor, the inlet gasification gas temperature of the cryogenic compressor should be kept constant. To this end, LNG is injected from the shear cooler upstream of the cryogenic compressor to cool the natural gasification gas. The low temperature vaporization gas was introduced into the cryogenic compressor.

On the other hand, the way in which a fuel gas supply system is driven in an LNG vessel is largely carried out in a state in which LNG is filled in an LNG storage tank of an LNG carrier, and an LNG carrier is operated in an empty state after carrying all LNG. It is divided into cases.

When the LNG is transported in the LNG storage tank of the LNG carrier in a state filled with LNG, since the amount of vaporized gas generated from the LNG storage tank is large, the vaporized gas remains after driving the dual fuel engine. In this case, the dual fuel engine is driven and the remaining vaporized gas is combusted in a gas combustion unit (GCU).

When the LNG carrier operates in a collinear state, the amount of vaporized gas to be naturally vaporized is not large, so the vaporized gas is forcibly generated by the forced evaporator to drive the dual fuel engine.

Here, the vaporization gas supply system of the dual fuel engine according to the prior art, the cryogenic compressor in spite of the large amount of vaporization gas generated from the LNG storage tank when the LNG is transported in a state filled with LNG inside the LNG storage tank of the LNG carrier Since the LNG had to be injected from the shear cooler to lower the temperature of the vaporized gas introduced into the fuel cell, the amount of surplus vaporized gas remaining after driving the dual fuel engine was increased.

In addition, the vaporization gas supply system of the dual fuel engine according to the prior art has a problem that the life of the pump is shortened and the efficiency is lowered because the pump must be continuously operated to inject LNG from the shear cooler.

The present invention has been made to solve the above problems, it is an object of the present invention to provide a fuel gas supply system and a vessel having the same can reduce the amount of gas generated.

In order to achieve the above object, according to an aspect of the present invention, a compressor for compressing the vaporized gas vaporized from the inside of the LNG storage tank, a cooler installed in the downstream of the compressor to cool the compressed vaporized gas, And a supply conduit for supplying the cooled vaporized gas to the dual fuel engine, wherein the amount of vaporized gas introduced into the compressor is equal to the amount of vaporized gas discharged from the LNG storage tank.

The compressor may be a multistage compressor.

The compressor may be a cryogenic compressor or a reciprocating compressor. Alternatively, the fuel gas supply system described above may further include a heater for heating the vaporized gas introduced into the compressor, and the compressor may use a room temperature compressor.

The cooler may comprise a plurality of coolers each installed downstream of each stage of the multistage compressor. Here, the above-described fuel gas supply system further includes at least one bypass line installed between each of the multistage compressors, and at least one bypass valve installed in the bypass line, wherein the fuel gas supply system passes through the multistage compressor. The bypass valve may be opened and closed according to temperature.

Alternatively, the cooler of the fuel gas supply system described above may be one cooler installed downstream of the multistage compressor.

The fuel gas supply system described above may further include a feed pump installed inside the LNG storage tank and a forced evaporator for forcibly evaporating the LNG supplied from the feed pump to the compressor. The apparatus may further include a mist separator separating the mist from the vaporized gas introduced into the compressor from the forced evaporator.

In addition, the fuel gas supply system described above may further include a gas combustion unit which is installed branched from the supply conduit in which the vaporized gas cooled by the cooler is supplied to the dual fuel engine.

According to another aspect of the present invention, there is provided a vessel comprising an LNG storage tank, a dual fuel engine, and a fuel gas supply system for supplying fuel gas to a dual fuel engine as described above.

According to the present invention, since the vaporized gas from the LNG storage tank is not cooled by the LNG separately before entering the compressor, the excess vaporized gas is not generated much.

In addition, the configuration of the fuel gas supply system and the vessel equipped with the fuel gas supply system is simplified and the efficiency is improved by not installing the shear cooler to cool the vaporized gas before the vaporized gas from the LNG storage tank is introduced into the compressor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a fuel gas supply system according to a first embodiment of the present invention.

Referring to FIG. 1, the fuel gas supply system 1 according to the first embodiment of the present invention may include a multi-stage compressor 30, a cooler 90, a forced evaporator 80, and a mist connected to an LNG storage tank 10. Separator 20, feed conduit 42.

The multi-stage compressor 30 is a component for compressing the gas vaporized from the LNG storage tank 10.

For reference, the multi-stage compressor 30 may be configured in two or three stages or more according to the temperature and gas amount of the vaporized gas to be compressed. In this embodiment, the multi-stage compressor 30 includes three compressors 32 and 34. It consists of a three stage compressor consisting of 36 ,. For convenience of description, hereinafter, the compressors in which the natural vaporization gas is introduced among the three-stage compressors are first compressors 32 and compressors sequentially arranged downstream of the first compressors 32. 36).

The vaporized gas introduced into the first compressor 32 is introduced into the first compressor 32 in a state in which the vaporized gas is evaporated from the LNG storage tank and flowed out without additional temperature control before entering the first compressor 32. At this time, in the present embodiment, since the vaporized gas introduced into the multi-stage compressor 30 without additional temperature control is a cryogenic state, the multi-stage compressor into which the vaporized gas in such a cryogenic state is introduced uses the cryogenic multistage compressor 30.

At this time, the amount of vaporized gas flowing into the first compressor 32 is formed to be equal to the amount of vaporized gas discharged from the LNG storage tank 10.

The vaporized gas compressed by the first compressor 32 flows into the first cooler 92 provided downstream of the first compressor 32. Here, the cooler 90 of the present embodiment includes a plurality of coolers 92, 94, 96 connected downstream of the stages of the first to third compressors 32, 34, and 36, respectively.

The vaporized gas passing through the first compressor 32 is cooled by the first cooler 92. According to the first embodiment of the present invention, the first cooler 92 may use a cooler cooled with fresh water. At this time, the first cooler 92 may be configured by using a general cooling device or by using a cooling system that is previously installed in a vessel (not shown).

On the other hand, a second compressor 34 is installed downstream of the first cooler 92, and a second cooler 94 is installed downstream of the second compressor 34.

The downstream side of the second cooler 94 is provided with a third compressor (36) constituting the last stage of the multi-stage compressor, the vaporized gas passing through the third compressor 36 is a dual fuel engine (3) in the third cooler (96) Cooled to an appropriate temperature for inflow to 60).

At this time, the number and performance of each compressor of the multi-stage compressor 30 may be formed differently, and also the pressure and first to third compressors 32, 34, 36 necessary for driving the dual fuel engine 60. Various selections may be made depending on the cooling performance of the first to third coolers 92, 94, and 96 installed downstream.

Coolers 92, 94, and 96 installed downstream of each compressor 32, 34, and 36 are all installed downstream of each compressor 32, 34, and 36, depending on the state of the vaporized gas to be compressed, or The cooler 92 and the second cooler 94 may be omitted.

At this time, it is preferable that the installation of the third cooler 96 for cooling the vaporized gas passing through the third compressor 36 is not omitted. This is because, in the first embodiment of the present invention, a process of cooling the vaporized gas passed through the multi-stage compressor 30 to an appropriate temperature for entering the dual fuel engine 60 is necessary.

The vaporized gas cooled through the multi-stage compressor 30 and the plurality of coolers 92, 94, and 96 at a predetermined pressure and temperature is a supply conduit connecting the third cooler 96 and the dual fuel engine 60. It enters into the dual fuel engine 60 through 42.

On the other hand, a gas combustion unit (GCU) 70 is installed in the conduit 44 branched from the supply conduit 42. The gas combustion unit 70 burns the remaining vaporized gas when the vaporized gas is excessively supplied while the vaporized gas is supplied to the dual fuel engine 60.

Meanwhile, according to the first embodiment of the present invention, a forced evaporator 80 is installed between the LNG storage tank 10 and the multistage compressor 30.

The forced evaporator 80 is a component for forcibly vaporizing LNG and supplying the dual fuel engine 60 when there is little LNG vaporization gas in the LNG storage tank 10.

The forced evaporator 80 is connected by a conduit 22 to a feed pump 50 installed inside each LNG storage tank 12, 14, 16, 18, and receives LNG supplied by the feed pump 50. Forced evaporation

The vaporized gas forcibly evaporated by the forced evaporator 80 is supplied to the first compressor 32 after the mist is separated from the mist separator 20 downstream of the forced evaporator 80.

According to the first embodiment of the present invention, vaporized gas from the plurality of LNG storage tanks 12, 14, 16, 18 is introduced into the compressor through one inlet conduit 24.

As a result, the vaporized gas discharged from the plurality of LNG storage tanks 12, 14, 16, and 18 is introduced into the first compressor 32 by forming one fluid stream in the inlet conduit 24.

The vaporized gas introduced into the forced evaporator 80 through the conduit 22 by the feed pump 50 from the plurality of LNG storage tanks 12, 14, 16 and 18 is evaporated by the forced evaporator 80. , Through the mist separator 20, is introduced into the inlet conduit 24 through the conduit 26.

With the above configuration, when the fuel gas supply system 1 according to the first embodiment of the present invention is applied to an LNG carrier, the LNG storage tank 10 is filled with LNG in the LNG storage tank 10. The vaporized gas which is naturally vaporized in the gas is introduced into the multi-stage compressor 30 through the inlet conduit 24, and then the gaseous gas which has passed the multi-stage compressor 30 and the plurality of coolers 90 is a dual fuel engine ( 60).

At this time, in the state in which the vaporization gas supplied to the dual fuel engine 60 is an excess supply, vaporization gas is supplied to the gas combustion unit 70 as above-mentioned, and the excess vaporization gas is combusted.

The fuel gas supply system 1 according to the first embodiment of the present invention has the inlet conduit 24 because the vaporized gas is introduced into the multi-stage compressor 30 at a pressure and a temperature in a state where the vaporized gas flows out of the LNG storage tank 10. There may be some pressure and temperature changes during the passage, but are not forcedly cooled by separate LNG before entering the multi-stage compressor 30.

Therefore, since the fuel gas supply system 1 according to the embodiment of the present invention does not additionally introduce LNG to cool the natural vaporization gas as in the conventional fuel gas supply system, The amount of gas does not increase before it enters the multistage compressor 30.

Accordingly, in the fuel gas supply system 1 according to the first embodiment of the present invention, the gaseous gas is excessively supplied to the dual fuel engine 60 so that the excessively supplied gaseous gas is combusted in the gas combustion unit 70. Can be prevented or significantly reduced.

On the other hand, in the fuel gas supply system 1 according to the first embodiment of the present invention, the amount of LNG in the LNG storage tank 10 is the same as when the LNG carrier returns to an empty state after transporting LNG to a destination. When this very small amount remains, the LNG in the LNG storage tank 10 is forcibly evaporated by the forced evaporator 80 and then supplied to the dual fuel engine 60. At this time, since the process of supplying the vaporized gas after passing through the forced evaporator 80 and the mist separator 20 is the same as described above, a redundant description thereof will be omitted.

2 shows a fuel gas supply system 2 according to a second embodiment of the invention.

The fuel gas supply system 2 according to the second embodiment shown in FIG. 2 is distinguished from the fuel gas supply system 1 according to the first embodiment of the present invention in that a heater is installed upstream of the multistage compressor. .

Hereinafter, in describing the fuel gas supply system 2 according to the second embodiment of the present invention, the same configuration as that of the fuel gas supply system 1 according to the first embodiment of the present invention will be omitted.

The fuel gas supply system 2 according to the second embodiment of the present invention, in order to heat the vaporized gas to room temperature in the process of supplying the vaporized gas from the LNG storage tank 10 to the multi-stage compressor 30a, The heater 75 is provided on the upstream side of the multistage compressor 30a in the flow direction.

The heater 75 may use a shell and tube heat exchanger.

In the second embodiment of the present invention, since the vaporized gas is heated to room temperature while passing through the heater 75, a normal temperature compressor is used as the multistage compressor 30a for compressing the vaporized gas. Accordingly, the multistage compressor 30a is formed of a plurality of room temperature compressors 32a, 34a, and 36a.

A plurality of coolers 92, 94, and 96 for cooling the vaporized gas from the multistage compressor 30a are provided on the downstream side of each of the multistage compressors 30a 32a, 34a, and 36a.

The fuel gas supply system 2 according to the second embodiment of the present invention is provided to the multistage compressor 30a and the multistage compressor 30a after the vaporized gas discharged from the LNG storage tank 10 is heated by the heater 75. Compressed and cooled by the connected cooler 90, the compressed and cooled vaporized gas is formed to be supplied to the dual fuel engine 60.

Therefore, since the fuel gas supply system 2 according to the second embodiment of the present invention does not go through the process of injecting and cooling LNG in the supply process of the vaporized gas, before entering the multi-stage compressor 30a, The amount of vaporization gas does not increase. Therefore, excessive supply of vaporization gas to the dual fuel engine 60 can be prevented.

3 shows a fuel gas supply system 3 according to a third embodiment of the invention.

Referring to FIG. 3, the fuel gas supply system 3 according to the third embodiment of the present invention passes through the heater 75 by using vaporized gas that has passed through the third compressor 36a of the multistage compressor 30a. Thereby further preheating the heated vaporization gas.

The vaporized gas which has passed through the third compressor 36a is supplied to the preheater 85 through the conduit 41 and introduced into the first compressor 32a via the heater 75 while passing through the preheater 85. Preheat additionally.

Therefore, compared with the second embodiment, the fuel gas supply system 3 according to the third embodiment of the present invention can reduce the heat exchange capacity required for heating the vaporized gas in the heater 75, thereby further improving the energy efficiency. do.

4 shows a fuel gas supply system 3 according to a fourth embodiment of the invention.

In the fuel gas supply system 3 according to the fourth embodiment of the present invention shown in FIG. 4, the multistage compressor 30 is configured as a multistage compressor like the fuel gas supply system 1 according to the first embodiment of the present invention. However, a plurality of coolers are not installed downstream of each stage of each of the first to third compressors 32, 34, and 36, and a large cooler 90a is installed downstream of the third compressor 36.

That is, the fuel gas supply system 4 according to the fourth embodiment of the present invention controls the pressure and temperature of the vaporized gas flowing into the dual fuel engine 60 by using one large cooler 90a. It is distinguished from the fuel gas supply system 1 according to the first embodiment of the invention.

In this case, the large cooler 90a may be configured using low temperature fresh water mainly used in a ship, or a separate cooler may be installed.

5 shows a fuel gas supply system 5 according to a fifth embodiment of the invention.

Referring to FIG. 5, the fuel gas supply system 5 according to the fifth embodiment of the present invention includes bypass lines 33 and 35 and bypass valves 33a and 35a. Then, the reciprocating compressor is arranged in multiple stages by the multi-stage compressor 30b.

In order to increase the efficiency of the dual fuel engine 60, it is necessary to properly adjust the temperature and pressure of the vaporized gas supplied. Accordingly, the fuel gas supply system 5 according to the fifth embodiment of the present invention adjusts the temperature and pressure of the vaporized gas by using the multistage compressor 30b and the cooler 90.

In order to further improve the temperature and pressure regulating ability of such vaporized gas, the fuel gas supply system 5 according to the fifth embodiment of the present invention is provided with a bypass line to each of the multi-stage compressors 30b 32, 34, 36. 33 and 35 are provided, and bypass valves 33a and 35a are provided in the bypass lines 33 and 35.

The bypass valves 33a and 35a are opened and closed in accordance with the temperature of the vaporized gas which has passed through the multi-stage compressor 30b. That is, when the temperature of the vaporized gas passing through the multi-stage compressor 30b is higher than the temperature suitable for supplying the dual fuel engine 60, the bypass valves 33a and 35a are closed to allow the vaporized gas to cool the coolers 92 and 94. Let it pass

When the temperature of the vaporized gas is lower than a temperature suitable for supplying the dual fuel engine 60, the bypass valves 33a and 35a are opened to pass through the compressors 32b and 34b and the compressed vaporized gas is cooled to the cooler 92. 94 and pass through bypass lines 33 and 35 to prevent cooling of the vaporized gas.

To this end, although not shown, the supply conduit 42 is provided with means such as a temperature sensor for measuring the temperature of the vaporized gas, and receives the signal of the temperature sensor to control the opening and closing of the bypass valves 33a and 35a. The adjusting means is further installed.

In the reciprocating compressor, the discharge pressure is not affected by the change in the inlet temperature of the vaporized gas. That is, the vaporized gas compressed by the compressors 32b, 34b, and 36b can maintain a constant discharge pressure.

Therefore, the fuel gas supply system 5 according to the fifth embodiment of the present invention can adjust the temperature and pressure of the vaporized gas to a temperature and pressure suitable for supplying the dual fuel engine 60, the dual fuel engine 60 ) Can maximize the efficiency.

Here, the fuel gas supply system 5 according to the fifth embodiment of the present invention has been described as having two bypass lines 33 and 35 and two bypass valves 33a and 35a installed. The number of 33 and 35 and the bypass valves 33a and 35a can be added or subtracted as needed.

In the fuel gas supply system and the ship having the same according to the embodiments of the present invention described above, the number and capacity of the coolers installed in the multistage compressor may be variously modified according to the state and capacity of the vaporized gas to be cooled. Can be. The cooler lowers the temperature of the vaporized gas so as to be appropriately supplied to the dual fuel engine, and may act to increase the temperature of the vaporized gas when the temperature of the vaporized gas is lower than the appropriate temperature.

As such, the number and capacity of coolers, the type of compressor, and the like do not limit the spirit of the present invention.

For reference, the fuel gas supply system according to embodiments of the present invention may be applied to a vessel equipped with a dual fuel engine, and in particular, when applied to LNG carriers, BOG generated from an LNG storage tank may be used as a propulsion fuel of a vessel. The effect can be obtained.

Although the fuel gas supply system and the ship having the same according to embodiments of the present invention have been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention Within the scope of the same idea, other embodiments may be easily proposed by adding, changing, deleting or adding components, but this will also fall within the scope of the present invention.

1 is a configuration diagram of a fuel gas supply system according to a first embodiment of the present invention.

2 is a configuration diagram of a fuel gas supply system according to a second embodiment of the present invention.

3 is a configuration diagram of a fuel gas supply system according to a third embodiment of the present invention.

4 is a configuration diagram of a fuel gas supply system according to a fourth embodiment of the present invention.

5 is a configuration diagram of a fuel gas supply system according to a fifth embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

1, 2, 3, 4, 5: fuel gas supply system

10: LNG storage tank 20: mist separator

30, 30a, 30b: multistage compressor 50: feed pump

60: dual fuel engine 70: gas combustion unit

75: heater 80: forced evaporator

85: preheater 90, 90a: cooler

Claims (11)

A compressor for compressing the vaporized gas vaporized from inside the LNG storage tank; A cooler installed downstream of the compressor to cool the compressed vaporized gas; And A supply conduit for supplying the vaporized gas cooled by the cooler to the dual fuel engine, The amount of vaporized gas introduced into the compressor is the same as the amount of vaporized gas discharged from the LNG storage tank. The method of claim 1, And said compressor is a multistage compressor. The method of claim 2, The compressor is a fuel gas supply system, characterized in that the cryogenic compressor or reciprocating compressor. The method of claim 2, Further comprising a heater for heating the vaporized gas flowing into the compressor, The compressor is a fuel gas supply system, characterized in that the room temperature compressor. The method according to any one of claims 2 to 4, And said cooler comprises a plurality of coolers respectively installed downstream of each stage of said multistage compressor. The method of claim 5, At least one bypass line disposed between each of the multistage compressors; And At least one bypass valve installed in the bypass line, And the bypass valve opens and closes according to the temperature of the vaporized gas passing through the multi-stage compressor. The method according to any one of claims 2 to 4, And said cooler is one cooler installed downstream of said multi-stage compressor. The method of claim 1, A feed pump installed inside the LNG storage tank; And And a forced evaporator for forcibly evaporating the LNG supplied from the feed pump to the compressor. The method of claim 8, And a mist separator for separating mist from vaporized gas introduced from the forced evaporator to the compressor. The method of claim 1, And a gas combustion unit in which vaporized gas cooled by the cooler is branched from the supply conduit supplied to the dual fuel engine. LNG storage tanks; Dual fuel engine; And A ship provided with a fuel gas supply system according to any one of claims 1 to 4, for supplying fuel gas to the dual fuel engine.

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