KR20110074165A - System for capturing carbon dioxide from exhaust gas - Google Patents

Abstract

PURPOSE: A system for collecting carbon dioxide from exhaust gas is provided to prevent carbon dioxide from becoming discharged to the air since carbon dioxide in exhaust gas discharged from the engine of a ship is collected and stored. CONSTITUTION: A system for collecting carbon dioxide from exhaust gas comprises storage tanks(111, 112, 113, 114, 115, 116), a first heat exchanger(151), a second heat exchanger(155) and a compressor(154). The storage tank stores LNG. The first heat exchanger and the second heat exchanger vaporize LNG provided from the storage tank. The compressor is installed between the first heat exchanger and the second heat exchanger.

Description

CO2 capture system in exhaust gas {SYSTEM FOR CAPTURING CARBON DIOXIDE FROM EXHAUST GAS}

The present invention relates to a carbon dioxide capture system in the exhaust gas, and to a carbon dioxide capture system included in the exhaust gas of a vessel using liquefied natural gas as fuel.

As interest in increasing atmospheric carbon dioxide concentrations increases, countries are limiting the amount of carbon dioxide they can emit. In recent years, interest in carbon dioxide emitted from ships has increased, and the movement to regulate the amount of carbon dioxide emitted from ships has intensified.

As part of this, ships using liquefied natural gas as fuel, which generates less air pollutants, have started to appear, and the amount of carbon dioxide emitted when liquefied natural gas is used as fuel is only about 20%.

In particular, in the case of ships, when regulations on carbon dioxide emission are tightened, ships cannot be used, which may cause enormous losses.

The present invention has been made to solve the problems described above, according to the present invention can collect carbon dioxide from the exhaust gas of the vessel using liquefied natural gas as fuel.

In order to achieve the above object, according to an aspect of the present invention, a carbon dioxide collection system of the exhaust gas of the ship equipped with an engine for vaporizing the liquefied natural gas as a fuel, a plurality of storage for storing the liquefied natural gas A tank, a first heat exchanger and a second heat exchanger for vaporizing the liquefied natural gas supplied from the storage tank, and a compressor installed between the first heat exchanger and the second heat exchanger, wherein the vaporized liquefied natural gas is burned in the engine. The generated exhaust gas is introduced into the first heat exchanger to exchange heat with the liquefied natural gas passing through the second heat exchanger, and the exhaust gas passing through the first heat exchanger passes through the compressor to the second heat exchanger and is supplied to the second heat exchanger. A carbon dioxide capture system is provided in the exhaust gas which is heat exchanged with natural gas.

The carbon dioxide collection system of the exhaust gas may further include a condensate discharge line connected to the first heat exchanger, such that condensate generated by condensation of moisture contained in the exhaust gas in the first heat exchanger may be discharged through the condensate discharge line. . Further, the method may further include a liquefied carbon dioxide collection line connected to the second heat exchanger, so that the liquefied carbon dioxide generated by liquefying carbon dioxide included in the exhaust gas in the second heat exchanger may be discharged through the liquefied carbon dioxide collection line.

Alternatively, the carbon dioxide collection system in the exhaust gas further includes a first gas-liquid separator installed between the first heat exchanger and the compressor, and a condensate discharge line connected to the first gas-liquid separation, so that the moisture contained in the exhaust gas is supplied to the first heat exchanger. The condensate produced by condensation in the discharge may be discharged through the condensate discharge line. And a second gas-liquid separator into which the exhaust gas passing through the second heat exchanger is introduced, and a liquefied carbon dioxide collection line connected to the second gas-liquid separator, wherein carbon dioxide contained in the exhaust gas is liquefied in the second heat exchanger. Liquefied carbon dioxide can be discharged through the liquefied carbon dioxide collection line.

Here, the carbon dioxide capture system in the exhaust gas may further include a liquefied carbon dioxide storage tank connected to the liquefied carbon dioxide collection line.

Alternatively, the liquefied carbon dioxide collection line is connected to a plurality of storage tanks, and the plurality of storage tanks sequentially supply liquefied natural gas to the first heat exchanger and the second heat exchanger, and the liquefied natural gas is discharged from the plurality of storage tanks. The liquefied carbon dioxide can be stored in it. Here, the method may further include a storage tank in which liquefied carbon dioxide collected at an initial operation of the engine is stored.

The apparatus may further include a third heat exchanger installed between the engine and the first heat exchanger, and the exhaust gas passing through the second heat exchanger and the high temperature exhaust gas generated in the engine may be heat-exchanged by the third heat exchanger.

In addition, the fuel supply line installed between the plurality of storage tanks and the second heat exchanger, and further comprising an oxygen blocking means surrounding the fuel supply line, exhaust gas passing through the second heat exchanger may be introduced into the oxygen blocking means.

According to an embodiment of the present invention, by capturing and storing carbon dioxide contained in the exhaust gas discharged from the engine of the ship, it is possible to prevent carbon dioxide from being released into the atmosphere, and energy by utilizing the heat of the exhaust gas for vaporization of liquefied natural gas The use efficiency is increased, and the nitrogen gas separated from the exhaust gas can be used for preventing fire and explosion caused by gas leakage.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

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

Figure 1 is provided with a carbon dioxide capture system in the exhaust gas according to an embodiment of the present invention.

Referring to FIG. 1, a carbon dioxide collection system 100 of exhaust gas according to an embodiment of the present invention includes a plurality of storage tanks 111, 112, 113, 114, 115, and 116 and a first heat exchanger 151. , A compressor 154 and a second heat exchanger 155.

In the first to sixth storage tanks 111 to 116 are stored liquefied natural gas to be used as fuel in the engine 160 provided in the ship not shown. Carbon dioxide collection system 100 of the exhaust gas according to an embodiment of the present invention is provided with six storage tanks (111 to 116), the number of storage tanks can be added or subtracted as needed. Although not shown, only one storage tank may be provided when the capacity of the storage tank in which the liquefied natural gas is stored is large enough.

The fuel supply line 140 and the liquefied carbon dioxide collection line 156 are connected to the first to sixth storage tanks 111 to 116, respectively. First to sixth supply valves 131 to 136 are installed between the first to sixth storage tanks 111 to 116 and the fuel supply line 140, and the first to sixth storage tanks 111 to 136, respectively. The first to sixth collection valves 121 to 126 are installed between the 116 and the liquefied carbon dioxide collection line 156.

Here, "installed between" means a sequential connection relationship, which means that the liquefied natural gas and the exhaust gas to be described later are disposed on the path to move, and in terms of the actual arrangement relationship It does not mean that it is installed in '. This applies throughout this specification.

The fuel supply line 140 is sequentially supplied to the engine 160 through the second heat exchanger 155 and the first heat exchanger 151. Here, the engine 160 may use only liquefied natural gas as a fuel or a dual fuel engine, that is, a liquid fuel such as oil and vaporized liquefied natural gas may be used as fuel.

The engine 160 and the first heat exchanger 151 are connected to the exhaust line 161 so that the exhaust gas discharged from the engine 160 flows into the first heat exchanger 151. Exhaust gas introduced into the first heat exchanger 151 is compressed through a compressor 154 installed in a conduit 153 connecting between the first heat exchanger 151 and the second heat exchanger 155, and thus the second heat exchanger. Supplied to the unit 155.

The condensate discharge line 152 is connected to the first heat exchanger 151, and the liquefied carbon dioxide collection line 156 and the discharge line 157 for discharging the exhaust gas are connected to the second heat exchanger 155.

Discharge line 157 is provided with a switching valve 171, the switching valve 171 is a conduit 158 and exhaust gas for introducing the exhaust gas discharged through the discharge line 157 to the oxygen blocking means 170. An exhaust pipe 159 for discharging to the outside of the ship (not shown) is connected.

Here, the oxygen blocking means 170 is an outer tube surrounding the fuel supply line 140, the exhaust gas flows to the outside of the fuel supply line 140. One end of the oxygen blocking means 170 is connected to the conduit 158 for introducing the exhaust gas discharged through the discharge line 157, and the other end of the vessel (not shown) through the oxygen blocking means 170 Exhaust pipe 172 discharged to the outside of the) is connected.

Carbon dioxide capture system 100 of the exhaust gas according to an embodiment of the present invention having the structure as described above is operated as follows.

The liquefied natural gas stored in the first to sixth storage tanks 111 to 116 is vaporized through the second heat exchanger 155 and the first heat exchanger 151 through the fuel supply line 140, and then the engine 160. Is supplied. Here, since the high-temperature exhaust gas discharged from the engine 160 is supplied to the first heat exchanger 151 and the second heat exchanger 155 by the exhaust line 161, the liquefied natural gas is the second heat exchanger ( Through 155 and the first heat exchanger 151, heat exchange with the exhaust gas occurs to evaporate. The liquefied natural gas vaporized in this way is supplied to the engine 160 and used as fuel.

The exhaust gas discharged from the engine 160 includes carbon dioxide, nitrogen, water vapor, and the like. The high temperature exhaust gas introduced into the first heat exchanger 151 through the exhaust line 161 exchanges heat with the low temperature liquefied natural gas introduced into the first heat exchanger 151 after passing through the second heat exchanger 155. As it cools, moisture contained in the exhaust gas condenses. This moisture condenses to produce condensate, which is discharged out of the first heat exchanger 151 through the condensate discharge line 152.

Exhaust gas from which moisture is removed while passing through the first heat exchanger 151 is introduced into the compressor 154 through the conduit 153. The exhaust gas compressed by the compressor 154 flows into the second heat exchanger 155. Exhaust gas introduced into the second heat exchanger 155 may exchange heat with the cryogenic liquefied natural gas supplied from the first to sixth storage tanks 111 to 116. Liquefied natural gas is liquefied.

Here, since the triple point of the carbon dioxide is about 56.4 degrees Celsius and about 5.18 bar, the pressure of the triple point or more in the second heat exchanger 155 using the compressor 154 is liquefied carbon dioxide contained in the exhaust gas. Therefore, the exhaust gas is discharged to the outside of the ship through the discharge line 157 in a state in which carbon dioxide is removed from the second heat exchanger 155, and only nitrogen is left in the exhaust gas discharged through the discharge line 157. This will not adversely affect the atmosphere.

Here, the reason for first removing the moisture contained in the exhaust gas by using the first heat exchanger 151 is as follows. When the high temperature exhaust gas discharged from the engine 160 is directly heat exchanged with the cryogenic liquefied natural gas supplied from the first to sixth storage tanks 111 to 116, the condensed water is rapidly frozen and forms an ice layer to exchange heat. This is because the efficiency is sharply lowered.

Therefore, by first removing the moisture contained in the exhaust gas, the liquefaction efficiency of carbon dioxide may be increased in the second heat exchanger 155.

Carbon dioxide capture system 100 of the exhaust gas according to an embodiment of the present invention, using the liquefied natural gas stored in the first to sixth storage tank (111 to 116) sequentially. For example, the liquefied natural gas in the first storage tank 111 is supplied to the fuel supply line 140 by opening the first supply valve 131, and the liquefied natural gas stored in the first storage tank 111 is When all are exhausted, the first supply valve 131 is shut off and the second supply valve 132 is opened to supply liquefied natural gas to the fuel supply line 140.

All of the first to sixth collection valves 121 to 126 are in a closed state. As described above, after the liquefied natural gas stored in the first storage tank 111 is exhausted, the first collection valve 121 is opened. do. Then, the liquefied carbon dioxide collected by the second heat exchanger 155 flows into the first storage tank 111.

Since the main component of liquefied natural gas is methane, when one mole of methane is burned, about one mole of carbon dioxide is generated. Accordingly, although the amount of liquefied carbon dioxide collected may vary according to the combustion efficiency of the engine 160 or the heat exchange efficiency of the first heat exchanger 151 and the second heat exchanger 155, the first storage tank 111 may differ. The amount of liquefied carbon dioxide generated when all of the liquefied natural gas stored in the combustion is burned is an amount that can be stored in the first storage tank 111.

After the first storage tank 111 is filled with liquefied carbon dioxide and all the liquefied natural gas stored in the second storage tank 112 is exhausted, the first collection valve 121 and the second supply valve 132 are closed. The third supply valve 133 is opened to supply the liquefied natural gas to the second heat exchanger 155 through the fuel supply line 140. Then, the second collection valve 122 is opened to allow the liquid carbon dioxide to flow into the second storage tank 112 through the liquid carbon dioxide collection line 156.

As described above, the first to sixth storage tanks 111 to 116 may be used not only for storing liquefied natural gas but also for storing liquefied carbon dioxide.

In addition, any one of the first to sixth storage tanks 111 to 116 before the ship departs may be left empty without storing liquefied natural gas, or may further include an empty storage tank (not shown). In this case, since the carbon dioxide contained in the exhaust gas generated while starting to operate the engine 160 may be collected and stored, the exhaust gas containing carbon dioxide included in the exhaust gas may not be discharged from the initial operation of the engine 160. Can be.

However, in order to store the liquefied carbon dioxide in the first to sixth storage tanks 111 to 116, the first to sixth storage tanks 111 to 116 must be able to withstand an internal pressure of 7 bar or more. Here, 7 bar is the internal pressure that must be able to withstand the storage of liquefied carbon dioxide at a stable temperature and pressure conditions.

However, when the first to sixth storage tanks 111 to 116 are manufactured to withstand an internal pressure of 7 bar or more, the outer wall is made somewhat thicker, so that the load is increased, whereas the consumption of liquefied natural gas is reduced. have.

That is, the boil-off gas generated while storing the liquefied natural gas is the first to sixth storage tanks 111 to 116 in consideration of the pressure resistance performance of the first to sixth storage tanks 111 to 116. ) When the internal pressure is out of the safe range, it is incinerated by the incinerator (GCU, not shown) provided on the ship.

However, when the first to sixth storage tanks 111 to 116 can withstand the internal pressure of 7 bar or more, the first to sixth storage tanks 111 to 116 can withstand this pressure even if a considerable amount of evaporated gas is generated. Therefore, the amount of boil-off gas sent to the incinerator is significantly reduced. Therefore, the effect that the amount of liquefied natural gas that is not used as fuel and is discarded can be significantly reduced.

Although not shown, the first to sixth storage tanks 111 to 116 are used only for storing liquefied natural gas, and the liquefied carbon dioxide storage tank capable of withstanding internal pressure of 7 bar or more in the carbon dioxide collection system 100 in exhaust gas. It is also possible to install separately.

On the other hand, although not shown, a nitrogen gas generator is installed in a ship carrying liquefied natural gas, liquefied petroleum gas and crude oil, and the liquefied natural gas, liquefied petroleum gas and crude oil are installed in the nitrogen gas generated by the nitrogen gas generator. It is injected into a storage tank that stores lamps and lowers the oxygen concentration to prevent fire and explosion.

In particular, liquefied natural gas carriers are typically re-docked into the dock for maintenance at intervals of about five years. Inert gas is used to clean the storage tank. . To this end, the LNG carrier is provided with an inert gas generator and a dryer for removing moisture from the inert gas.

As described above, the carbon dioxide collection system 100 of the exhaust gas according to an embodiment of the present invention discharges nitrogen gas from which moisture is removed through the discharge line 157. Therefore, the use of nitrogen gas discharged through the discharge line 157 into the storage tank for storing liquefied natural gas, liquefied petroleum gas, crude oil, etc. to lower the oxygen concentration, or to clean the storage tank during re docking In this case, the nitrogen generator, the inert gas generator, and the dryer as described above do not need to be installed on the ship, or the capacity thereof can be reduced.

Carbon dioxide capture system 100 of the exhaust gas according to an embodiment of the present invention, the nitrogen gas discharged through the exhaust line 157 using the switching valve 171 through the exhaust pipe 159 (not shown) ) Or to the outside, or nitrogen gas flows through the oxygen blocking means 170 through the conduit 158 to be discharged to the exhaust pipe 172. That is, by blocking the contact of the fuel supply line 140 with oxygen using nitrogen gas, even if the liquefied natural gas leaks from the fuel supply line 140, an accident such as a fire and an explosion may be prevented.

Although not shown, oxygen blocking means 170 may also be applied to the fuel supply line 140 between the second heat exchanger 155 and the first heat exchanger 151, and between the first heat exchanger 151 and the engine 160. An outer tube such as) may be installed.

Figure 2 shows a carbon dioxide capture system in the exhaust gas according to another embodiment of the present invention.

2, the carbon dioxide collection system 200 in the exhaust gas according to another embodiment of the present invention is a plurality of storage tanks (211, 212, 213, 214, 215, 216), the first heat exchanger (251), The compressor 254 includes a second heat exchanger 255, a first gas liquid separator 270, a second gas liquid separator 280, and a third heat exchanger 290.

Fuel supply lines 240 for supplying liquefied natural gas stored therein to the engine 260 are connected to the first to sixth storage tanks 211 to 216, respectively. The liquefied carbon dioxide collection lines 286 are connected to the first to sixth storage tanks 211 to 216, respectively.

First to sixth supply valves 231 to 236 are respectively installed between the first to sixth storage tanks 211 to 216 and the fuel supply line 240, and the first to sixth storage tanks 211 to 216. The first to sixth collection valves 221 to 226 are installed between the liquefied carbon dioxide collection line 286.

The fuel supply line 240 is connected to the engine 260 via the second heat exchanger 255 and the first heat exchanger 251. A third heat exchanger 290 is installed between the engine 260 and the first heat exchanger 255. The exhaust gas discharged from the engine 260 flows into the third heat exchanger 290 through an exhaust line 261 connecting the engine 260 and the third heat exchanger 290.

The exhaust gas passing through the third heat exchanger 290 flows into the first heat exchanger 251. The exhaust gas introduced into the first heat exchanger 251 is heat-exchanged with the liquefied natural gas introduced into the first heat exchanger 251 through the second heat exchanger 252 to condense moisture contained in the exhaust gas.

At this time, the first gas-liquid separator 270 is installed between the first heat exchanger 251 and the compressor 254. The exhaust gas containing the condensed water flows into the first gas-liquid separator 270 to become a liquid state. Moisture is separated from the gaseous exhaust gas. Water, which has become a liquid state, is condensed water and is discharged through the condensate discharge line 272 connected to the first gas-liquid separator 270.

Exhaust gas from which water is removed while passing through the first gas-liquid separator 270 is introduced into the compressor 254 through the conduit 273, compressed, and then introduced into the second heat exchanger 255. The exhaust gas introduced into the second heat exchanger 255 is heat-exchanged with the cryogenic liquefied natural gas supplied from the first to sixth storage tanks 211 to 216, and in this process carbon dioxide contained in the exhaust gas is liquefied.

Exhaust gas containing carbon dioxide liquefied through the second heat exchanger 255 is introduced into the second gas-liquid separator 280 through the conduit 256. A capture line 286 and a discharge line 287 are connected to the second gas-liquid separator 280, so that the liquid carbon dioxide in the liquid state is introduced into the capture line 286, and the exhaust gas in the gaseous state is discharge line 287. Flows into.

The discharge line 287 is connected to the third heat exchanger 290 so that the exhaust gas passing through the second heat exchanger 255 flows into the third heat exchanger 290. Accordingly, in the third heat exchanger 290, the exhaust gas passing through the second heat exchanger 255 is discharged after heat exchange with the high temperature exhaust gas discharged from the engine 260.

According to another embodiment of the present invention, the first to sixth storage tanks 211 to 216, the first to sixth supply valves 231 to 236, and the first to sixth collections of the carbon dioxide collection system 200 in the exhaust gas according to the present invention. The valves 221 to 226 may include the first to sixth storage tanks (111 to 116 of FIG. 1) and the first to sixth tanks of the carbon dioxide collection system 100 of FIG. 1, respectively, according to an embodiment of the present invention. Since 6 supply valves (131 to 136 of FIG. 1) and 1st to 6th collection valves (121 to 126 of FIG. 1) are the same, overlapping description is abbreviate | omitted.

The carbon dioxide collection system 200 of the exhaust gas according to another embodiment of the present invention uses the first gas-liquid separator 270 to separate the moisture contained in the exhaust gas passed through the first heat exchanger 251 to the maximum, thereby obtaining a second The heat exchange efficiency of the heat exchanger 255 is improved. In addition, the carbon dioxide collection system 200 of the exhaust gas according to another embodiment of the present invention by using the second gas-liquid separator 280 to collect the efficiency of the carbon dioxide contained in the exhaust gas passed through the second heat exchanger 255 Improve.

In addition, in the carbon dioxide collection system 200 of the exhaust gas according to another embodiment of the present invention, the low temperature exhaust gas discharged through the exhaust line 287 is discharged from the engine 260 by the third heat exchanger 290. Heat exchange with hot exhaust gas from

That is, by lowering the temperature of the exhaust gas flowing into the first heat exchanger 251, condensation of moisture contained in the exhaust gas is further promoted in the first heat exchanger 251, and in the second heat exchanger 255, Since the liquefaction is further promoted, the carbon dioxide collection efficiency of the carbon dioxide capture system 200 in the exhaust gas is improved.

In addition, since the purity of the nitrogen gas of the exhaust gas discharged through the discharge line 287 is also increased, the use of reducing the oxygen concentration by injecting the exhaust gas into the storage tank as described with reference to FIG. There is an effect that is more suitable for use for cleaning the purpose and for the purpose of blocking the fuel supply line 240 in contact with oxygen.

For reference, the carbon dioxide collection system 100 and 200 of the exhaust gas according to the embodiments of the present invention may use the engine 160 in the process of vaporizing the liquefied natural gas to use the liquefied natural gas as the fuel of the engines 160 and 260. Since the heat of the exhaust gas discharged from 260 is used, the energy use efficiency is increased by not supplying additional energy to the vaporization of the liquefied natural gas.

In the above description of the carbon dioxide capture system in the exhaust gas according to an embodiment of the present invention, the spirit of the present invention is not limited to the embodiments presented herein, those skilled in the art to understand the spirit of the present invention the scope of the same idea Within the scope of the present invention, other embodiments may be easily proposed by adding, changing, deleting, adding, etc., but this is also within the scope of the present invention.

1 is a carbon dioxide capture system in the exhaust gas according to an embodiment of the present invention.

Figure 2 is a carbon dioxide capture system in the exhaust gas according to another embodiment of the present invention.

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

111, 112, 113, 114, 115, 116: storage tank

121, 122, 123, 124, 125, 126: collection valve

131, 132, 133, 134, 135, 136: fuel supply valve

140: fuel supply line 150: carbon dioxide liquefaction unit

151: first heat exchanger 152: condensate discharge line

154: compressor 155: second heat exchanger

156: collection line 157: discharge line

160: engine 161: exhaust line

170: oxygen blocking means

Claims (10)

As a carbon dioxide capture system of the exhaust gas of a ship equipped with an engine for vaporizing liquefied natural gas as a fuel, A plurality of storage tanks for storing the liquefied natural gas; A first heat exchanger and a second heat exchanger for vaporizing the liquefied natural gas supplied from the storage tank; A compressor installed between the first heat exchanger and the second heat exchanger, The vaporized liquefied natural gas is combusted in the engine and the exhaust gas is introduced into the first heat exchanger to exchange heat with the liquefied natural gas passing through the second heat exchanger, The exhaust gas passing through the first heat exchanger is passed through the compressor and introduced into the second heat exchanger and heat exchanged with the liquefied natural gas supplied to the second heat exchanger. The method of claim 1, Further comprising a condensate discharge line connected to the first heat exchanger, And condensate generated by condensation of moisture contained in the exhaust gas in the first heat exchanger through the condensate discharge line. The method of claim 2, Further comprising a liquefied carbon dioxide capture line connected to the second heat exchanger, Liquefied carbon dioxide generated by liquefying carbon dioxide contained in the exhaust gas in the second heat exchanger is discharged through the liquefied carbon dioxide collection line, carbon dioxide capture system in the exhaust gas. The method of claim 1, A first gas-liquid separator installed between the first heat exchanger and the compressor; And Further comprising a condensate discharge line connected to the first gas-liquid separation, The condensate generated by condensation of water contained in the exhaust gas in the first heat exchanger is discharged through the condensate discharge line. 5. The method of claim 4, A second gas-liquid separator through which the exhaust gas passing through the second heat exchanger is introduced; And Further comprising a liquefied carbon dioxide capture line connected to the second gas-liquid separator, Liquefied carbon dioxide generated by liquefying carbon dioxide contained in the exhaust gas in the second heat exchanger is discharged through the liquefied carbon dioxide collection line, carbon dioxide capture system in the exhaust gas. The method according to claim 3 or 5, Carbon dioxide capture system in the exhaust gas further comprises a liquefied carbon dioxide storage tank connected to the liquefied carbon dioxide collection line. The method according to claim 3 or 5, The liquefied carbon dioxide collection line is connected to the plurality of storage tanks, The plurality of storage tanks sequentially supply the liquefied natural gas to the second heat exchanger and the first heat exchanger, The carbon dioxide capture system of the exhaust gas, characterized in that the liquefied carbon dioxide is stored in the discharge of all the liquefied natural gas of the plurality of storage tanks. The method of claim 7, wherein And a storage tank for storing liquefied carbon dioxide which is collected at an initial stage of operation of the engine. The method according to claim 3 or 5, Further comprising a third heat exchanger installed between the engine and the first heat exchanger, The exhaust gas passing through the second heat exchanger and the high temperature exhaust gas generated in the engine are heat-exchanged by the third heat exchanger. The method according to claim 3 or 5, A fuel supply line installed between the plurality of storage tanks and the second heat exchanger; And Further comprising an oxygen blocking means surrounding the fuel supply line, Exhaust gas having passed through the second heat exchanger is introduced into the oxygen blocking means.

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