Carbon dioxide capture and storage system for ship

Abstract

To improve carbon dioxide capture and storage capabilities, the present invention provides a carbon dioxide capture and storage system for a ship comprising: a fuel tank in which liquefied natural gas is stored as fuel for driving a main engine; a circulation tank in which liquefied carbon dioxide is stored; a deep cooling heat exchanger that deep cools the liquefied carbon dioxide supplied from the circulation tank using the regasification cold of the liquefied natural gas supplied from the fuel tank; a first post-treatment unit for post-treating exhaust gas generated during combustion in the main engine; a multi-stage separation and compression unit connected in series at multiple locations to repeatedly cool the exhaust gas introduced from the first post-treatment unit, separate condensate, and compress the exhaust gas; a second post-treatment unit for post-treating the exhaust gas discharged from the multi-stage separation and compression unit; and a deep cooling separation unit that separates the condensed liquefied carbon dioxide from the exhaust gas introduced from the second post-treatment unit through heat exchange with the liquefied carbon dioxide deep cooled in the deep cooling heat exchanger and drains it to the circulation tank.

Description

Technology Field

[0001] The present invention relates to a carbon dioxide capture and storage system for ships, and more specifically, to a carbon dioxide capture and storage system for ships with improved carbon dioxide capture and storage capabilities. Background Technology

[0002] Generally, due to the tightening of greenhouse gas emission regulations, there is an increasing need in the shipping industry for technologies capable of substantially reducing carbon dioxide (CO2) generated during ship operations. However, as completely replacing the existing fleet faces significant economic and time constraints, onboard carbon capture and storage (CPS) technology, which captures the aforementioned CO2 from exhaust gases during operation and stores it on board, is being considered as an alternative.

[0003] Specifically, the onboard carbon dioxide capture technology described above has a structure that pretreats the exhaust gas and then separates and concentrates the carbon dioxide through absorption, adsorption, or membrane separation methods. Accordingly, this technology is designed with a focus on improving capture efficiency and maximizing the removal rate, and improves performance by increasing the circulation flow rate.

[0004] However, since the pressure, temperature, and moisture conditions of the carbon dioxide stream generated after capture are not necessarily designed to match the downstream liquefaction storage conditions, there was a problem with limited connectivity between process steps.

[0005] Therefore, in order to store the captured carbon dioxide on board, a process of liquefying it through multi-stage compression and intermediate cooling is required. Furthermore, conventionally, a method of applying a compression-cooling-based liquefaction process utilized in industrial plants to a ship environment has been used.

[0006] Specifically, a structure is adopted in which the pressure is raised above a certain level, cooled to a low temperature through a heat exchanger, and liquefied carbon dioxide is recovered through phase separation. However, since many of these processes are designed under the premise of relatively stable conditions, there was a problem in that they could not adequately reflect load fluctuations or energy constraints during ship operation.

[0007] Specifically, the liquefaction section is highly sensitive to pressure and temperature conditions, so ensuring operational stability in the deep cold region is a critical technical challenge. However, if the condensate generated during the compression cooling process is not sufficiently removed or if residual moisture is not strictly managed, freezing or hydrate formation occurs in the low-temperature section, leading to problems such as blockage of the heat exchanger and piping.

[0008] Meanwhile, vent gas and drain streams are inevitably generated during the liquefaction process, and the non-condensing gas phase discharged from the phase separator may contain a certain amount of the carbon dioxide, and a small amount of the carbon dioxide may also be lost during the condensation and dehydration stages.

[0009] However, conventionally, there was a problem in that the loss of the carbon dioxide occurred because these loss streams were not clearly defined within the process boundaries, or the net storage amount based on the storage tank inflow was not set as a performance indicator.

[0010] Furthermore, in the case of dual-fuel liquefied natural gas (LNG)-diesel propulsion vessels, significant cold energy is generated during the LNG regasification process, which serves as a potential energy resource capable of offsetting the refrigeration load of the carbon dioxide liquefaction stage. However, there have been issues with reduced operational stability, as the utilization of this LNG cold energy is often limited to specific heat exchange sections and the capture, conditioning, compression, dehydration, liquefaction, and storage processes are not designed in an integrated manner. Prior art literature

[0011] Korean Registered Patent No. 10-2844903 The problem to be solved

[0012] In order to solve the above-mentioned problems, the present invention has as its objective to provide a carbon dioxide capture and storage system for ships. means of solving the problem

[0013] To solve the above problem, the present invention comprises: a fuel tank in which liquefied natural gas is stored as fuel for driving a main engine; a circulation tank in which liquefied carbon dioxide is stored; a deep cooling heat exchanger that deep cools the liquefied carbon dioxide supplied from the circulation tank using the regasification cold of the liquefied natural gas supplied from the fuel tank; a first post-treatment unit for post-treating exhaust gas generated during combustion in the main engine; a multi-stage separation and compression unit connected in series at multiple locations to repeatedly cool, separate condensate, and compress the exhaust gas introduced from the first post-treatment unit; and a second post-treatment unit for post-treating the exhaust gas discharged from the multi-stage separation and compression unit. The apparatus includes a deep cooling separation unit that separates condensed liquefied carbon dioxide from exhaust gas introduced from the second post-treatment unit through heat exchange with liquefied carbon dioxide deep-cooled in the deep cooling heat exchanger and drains it to the circulation tank, wherein the deep cooling separation unit includes a deep cooling cooler in which the liquefied carbon dioxide discharged from the circulation tank and deep cooling heat exchanged with the regasification cold of liquefied natural gas and the exhaust gas introduced from the second post-treatment unit exchanges heat, and a gas-liquid separator that separates the condensed liquefied carbon dioxide from the exhaust gas cooled and discharged from the deep cooling cooler and drains it to the circulation tank, and the liquefied carbon dioxide passing through the deep cooling heat exchanger and the deep cooling separation unit is recirculated to the circulation tank, and the multi-stage separation compression unit each includes a pre-cooling cooler that cools the exhaust gas by heat exchange with seawater, a separator that separates condensed water from the cooled exhaust gas, and pressurizes the exhaust gas from which the condensed water has been separated. A shipboard carbon dioxide capture and storage system is provided, characterized by including a compressor for compressing, and having multiple locations for pre-cooling and pressurizing the exhaust gas to a preset temperature and pressure for the condensation and separation of liquefied carbon dioxide through deep cooling heat exchange from the exhaust gas flowing into the deep cooling separation unit.

[0014] Meanwhile, the present invention comprises: a fuel tank in which liquefied natural gas is stored as fuel for driving a main engine; a circulation tank in which liquefied carbon dioxide is stored; a deep cooling heat exchanger that deep cools the liquefied carbon dioxide supplied from the circulation tank using the regasification cold of the liquefied natural gas supplied from the fuel tank; a first post-treatment unit for post-treating the exhaust gas generated during combustion in the main engine; a multi-stage separation and compression unit connected in series at multiple locations to pre-cool and pressurize the exhaust gas to a preset temperature and pressure for condensation and separation of the liquefied carbon dioxide through deep cooling by repeatedly cooling the exhaust gas introduced from the first post-treatment unit, separating condensate, and compressing the exhaust gas; and a second post-treatment unit for post-treating the exhaust gas discharged from the multi-stage separation and compression unit. The present invention provides a carbon dioxide capture and storage system for a ship comprising a deep cooling unit including a deep cooling cooler in which the liquefied carbon dioxide discharged from the circulation tank and subjected to deep cooling heat exchange in the deep cooling heat exchanger by the regasification cold of the liquefied natural gas, and the exhaust gas introduced from the second post-treatment unit, exchange heat; and a gas-liquid separator that separates the liquefied carbon dioxide condensed from the exhaust gas cooled and discharged from the deep cooling cooler and drains it to the circulation tank. Effects of the invention

[0015] Through the above-mentioned means of solution, the present invention provides the following effects.

[0016] First, by condensing and storing carbon dioxide from the ship's main engine exhaust gas using the cold energy generated during the regasification of liquefied natural gas, the emission of carbon dioxide from the ship can be reduced without using additional cooling energy, and operational stability can be significantly improved by reducing the risk of the ship's cooling process.

[0017] Second, by adjusting the number of multi-stage separation and compression units to pre-cool and pressurize the exhaust gas to a preset temperature and pressure using the multi-stage separation and compression units, the carbon dioxide condensation efficiency can be significantly improved during pre-cooling by the cold heat generated during the re-gasification of liquefied natural gas and deep cooling of the compressed exhaust gas. Brief explanation of the drawing

[0018] FIG. 1 is a block diagram of a carbon dioxide capture and storage system for a ship according to an embodiment of the present invention. Specific details for implementing the invention

[0019] Hereinafter, a carbon dioxide capture and storage system for ships will be described in detail with reference to the attached drawings.

[0020] First, exhaust gases may be emitted from the propulsion system of a dual-fuel vessel due to the fuel used. If such exhaust gases are directly introduced into a liquefaction process, problems such as water freezing, accumulation of impurities, and heat exchanger plugging may occur. Therefore, it is preferable to understand that the present invention performs a multi-stage separation and compression process for the capture and concentration of carbon dioxide.

[0021] FIG. 1 is a block diagram illustrating the process of capturing carbon dioxide in a carbon dioxide capture and storage system for ships according to an embodiment of the present invention.

[0022] Referring to FIG. 1, the dual-fuel vessel includes a fuel tank (1) in which liquefied natural gas (LNG) is stored as fuel for driving a main engine. And, it is preferable that the fuel tank be used to safely store the liquefied natural gas at minus 162°C.

[0023] Specifically, there is a modular tank that forms a large storage tank by combining several small modules, and a pressure tank designed to store the liquefied natural gas under high pressure, which is effective in preventing vaporization and leakage of the liquefied natural gas. Additionally, it may be provided to include at least one of a non-pressure tank designed to store a large amount of the liquefied natural gas under atmospheric pressure, and a double-walled tank having a double structure (inner wall-insulation-outer wall) to maximize leakage prevention and stability.

[0024] Then, the liquefied natural gas can be introduced into the deep cold heat exchanger (6) using a liquefied natural gas pump (1p) to supply it to the deep cold heat exchanger (6). Subsequently, the liquefied natural gas generated by heat exchange in the deep cold heat exchanger (6) can be introduced into the liquefied natural gas vaporizer (5). Furthermore, it is preferable to first feed the cold energy generated during the heat exchange process into the deep cold separation unit described later to assist in the condensation of liquid carbon dioxide (LCO2).

[0025] Subsequently, the liquefied natural gas transported to the liquefied natural gas vaporizer (5) is vaporized to supply fuel gas to the main engine (3), and at this time, cold heat is generated simultaneously with the vaporization of the liquefied natural gas. It is also preferable that this cold heat be connected to the deep cold separation unit. Meanwhile, diesel fuel stored in the diesel fuel tank (4) can also be supplied to the main engine (3) to operate the dual-fuel vessel.

[0026] Furthermore, it is preferable that the above dual-fuel vessel includes a circulation tank (2) in which liquefied carbon dioxide is stored. Specifically, it is preferable to understand the above circulation tank (2) as a device that stores the regasification cold of the liquefied natural gas supplied from the fuel tank (1) and the liquefied carbon dioxide supplied and deeply cooled from the deep cooling heat exchanger (6) that deeply cools the liquefied carbon dioxide described later.

[0027] In addition, the above circulation tank (2) is a vacuum insulated pressure vessel operated under low temperature conditions of -20°C to -50°C and high pressure conditions of about 1.5 MPa to 3.0 MPa. Therefore, it is desirable to use low-temperature high-strength materials such as stainless steel and to form an insulating structure that minimizes heat intrusion to maintain a stable liquid state.

[0028] Meanwhile, exhaust gas discharged from the main engine (3) of the above-mentioned dual-fuel vessel may be introduced into the first aftertreatment unit (20) through an exhaust pipe. At this time, since the temperature of the exhaust gas may typically be at the level of several hundred degrees, the exhaust gas may be controlled to an appropriate temperature by additionally providing a heat exchanger or cooling device for stable operation of the collection system.

[0029] In addition, pretreatment devices such as particle removal devices, mist removal devices, exhaust gas flow control devices, and temperature control devices may be included as needed. It is desirable to understand that these pretreatment processes are intended to ensure the safety of the capture process and prevent corrosion of downstream devices.

[0030] Meanwhile, the first post-treatment unit (20) preferably includes a dosing unit that doses the exhaust gas exhausted from the main engine (3) with ammonia (NH3) gas. Specifically, in the dosing unit, the ammonia gas may be introduced into a conversion reactor (26) to reduce the exhaust gas, and this may be reduced to nitrogen and water vapor by reacting with nitrogen oxides among the components of the exhaust gas.

[0031] Furthermore, diethylene glycol (DEG) may be introduced into the conversion reactor (26) to perform an absorption or cleaning function in the dosing section. The diethylene glycol can remove moisture from the exhaust gas to prevent the formation of methane hydrate, thereby preventing damage to the downstream liquefaction process.

[0032] Accordingly, impurities that could cause problems in the downstream liquefaction process can be removed in advance, a carbon dioxide-rich stream can be formed, and process stability can be improved.

[0033] Additionally, the first post-treatment unit (20) may further include a first separation control unit (25) that cools the exhaust gas introduced from the dosing unit with a first pre-cooling cooler (20a) to pre-separate the condensate with a first separator (21b) and controls the flow rate of the exhaust gas.

[0034] In detail, it is preferable that the exhaust gas introduced through the dosing section be introduced into the first pre-cooling cooler (20a). This first pre-cooling cooler (20a) may include a heat exchanger that uses seawater taken from outside the dual-fuel vessel as a cooling medium.

[0035] Specifically, it is preferable that the first pre-cooling cooler (20a) be equipped with a supply header for supplying the external fluid, which is seawater, and a recovery header for recovering the seawater after performing heat exchange with the exhaust gas. Accordingly, it is preferable to understand that the seawater is introduced into the first pre-cooling cooler (20a) through the supply header, cools the exhaust gas through heat exchange, and then the seawater is discharged through the recovery header.

[0036] In addition, stable intermediate separation can be supported by exchanging heat of the exhaust gas with seawater to reduce the temperature of the exhaust gas to a preset temperature, thereby inducing the formation of condensate and removing moisture.

[0037] In addition, the heat exchanger may include a shell-and-tube type heat exchanger, a plate type heat exchanger, or a fin type heat exchanger, and the seawater contact portion may be formed of a corrosion-resistant material such as titanium alloy or duplex stainless steel.

[0038] Afterwards, the exhaust gas cooled by the first pre-cooling cooler (20a) is moved to the first separator (21b) to remove the condensate, which is moisture contained in the exhaust gas, in the first step, and the remaining dry exhaust gas is preferably moved to the first separation control unit (25).

[0039] In addition, the first separation control unit (25) may have an excessive flow rate and composition of the carbon dioxide-rich stream contained in the exhaust gas introduced into the multi-stage separation and compression unit (30) described later. Therefore, a boundary condition setting function may be performed to force the input conditions to a feasible range for the downstream compression and liquefaction facility.

[0040] Accordingly, the flow rate and composition of the exhaust gas can be controlled to prevent overload and regime transition of the downstream compressor. Therefore, the first separation control unit (25) maintains input conditions that the compressor or the deep cryogenic separation unit can handle even when there is an engine load or fluctuation, and prevents sudden vent increase or liquefaction collapse of the downstream facility.

[0041] In addition, it is preferable to include a multi-stage separation and compression unit (30) connected in series at multiple locations to cool the exhaust gas introduced from the first post-treatment unit (10) and to repeat the separation of condensate and compression of the exhaust gas. At this time, although three locations are installed in the drawing, additional multi-stage separation and compression units (30) may be installed depending on the operating conditions of the dual-fuel vessel.

[0042] Specifically, the multi-stage separation and compression unit (30) preferably includes a pre-cooling cooler that cools the exhaust gas by exchanging heat with the external fluid, the seawater, a separator that separates the condensed water from the cooled exhaust gas, and a compressor that pressurizes and compresses the exhaust gas from which the condensed water has been separated.

[0043] First, the exhaust gas introduced from the first post-treatment unit (10) is introduced into the first compression unit (31) of the multi-stage separation and compression unit (30) and can be cooled by the second pre-cooling cooler (31a). Here, it is preferable that the second pre-cooling cooler (31a) induces cooling of the moisture by inducing the generation of condensate through heat exchange between the exhaust gas and the seawater.

[0044] Accordingly, the exhaust gas from which the condensate has been removed in the first compression section (31) can reduce the required compression power in the second compression section (35) where the next compression is performed, and induce the condensation of carbon dioxide to increase the carbon dioxide-rich stream.

[0045] Meanwhile, the exhaust gas that was introduced into the second pre-cooling cooler (31a) is moved to the second separator (32b), and the second separator (32b) can separate the condensate induced by the second pre-cooling cooler (31a) from the exhaust gas. Specifically, it is preferable that the condensate be drained through a drain line connected to the lower end of the second separator (32b). Afterward, it is preferable that the exhaust gas from which the condensate has been removed is introduced into the first compressor (33c).

[0046] In this case, it is preferable to understand that the drain stream refers to the flow of the aforementioned condensate, oil, etc., which is generated as a byproduct during the process and discarded outside the system.

[0047] Furthermore, the drain line may be measured directly or indirectly to measure the condensate flowing into the drain stream. Specifically, the drain line may be equipped with one or more of an electronic, ultrasonic, turbine, or thermal mass type that can be installed directly. Additionally, the discharge amount of the condensate may be determined by measuring based on pressure or indirectly through a velocity-measurement method.

[0048] Accordingly, since the condensate is drained through the drain line at the bottom of the second separator (32b), the inflow of moisture in the subsequent process can be blocked. Additionally, the closure of the energy balance of the dual-fuel vessel and the explicit management of the drain flow can be made possible.

[0049] Meanwhile, the separator may be a gravity-type separator capable of separating water and the liquid and gaseous carbon dioxide using the difference in fluid density. Additionally, it may be configured to include at least one of a cyclone separator that separates using the centrifugal force generated when the fluid rotates, and a co-alloying separator that separates fine droplets by colliding and combining them to form larger droplets.

[0050] Accordingly, the second separator (32b) separates the condensate condensed from the exhaust gas cooled in the second pre-cooling cooler (31a), thereby improving the purity of the carbon dioxide-rich stream supplied to the downstream process and enabling stable operation of the device.

[0051] Afterward, the exhaust gas may be moved to a first compressor (33c) and pressurized to a preset pressure to compress the exhaust gas. At this time, the gas temperature of the exhaust gas may rise significantly. Specifically, the exhaust gas has a temperature of about 40°C before compression, but after the exhaust gas is compressed, the gas temperature may rise from about 120°C to 200°C, so it is desirable to set an optimal pressure range from the perspective of system energy and operational stability rather than unconditionally high pressure.

[0052] And, it is preferable that the exhaust gas cooled and pressurized in the first compression unit (31) be moved to the second compression unit (35). Subsequently, a third pre-cooling cooler (35a) may be placed to lower the temperature of the exhaust gas that has risen due to the pressurization of the first compressor (33c) of the first compression unit (31).

[0053] In detail, in the third pre-cooling cooler (35a), the exhaust gas is compressed to a high pressure due to the pressurization in the first compression unit (31), and since the temperature of the exhaust gas becomes high due to the heat of compression, the heat of compression can be removed and the formation of the condensate can be induced.

[0054] Accordingly, the second compression unit (35) can further increase the purity of the carbon dioxide-rich stream and cool the remaining condensate once more. Specifically, the exhaust gas can be cooled by heat exchange with the seawater so that the seawater introduced through the seawater supply header provided in the third pre-cooling cooler (35a) drops below a preset temperature. And, it is preferable that the seawater be recovered through the recovery header. Afterwards, the exhaust gas can be moved to the third separator (36b).

[0055] Likewise, the condensate can be drained through the drain line provided at the bottom of the third separator (36b). By doing so, the purity of the carbon dioxide stream of the exhaust gas is further increased, and by preventing moisture from entering the compressor, damage to the compressor itself or damage to the compressor blades can be prevented in advance.

[0056] Then, the exhaust gas separated by the third separator (36b) is introduced into the second compressor (37c) and pressurized and compressed to a preset pressure. In this process, the purity of the carbon dioxide-rich stream of the exhaust gas can be increased. Afterward, the exhaust gas can be introduced into the third compression unit (39).

[0057] Accordingly, the exhaust gas pre-cooled and pressurized in the second compression unit (35) can be introduced into the third compression unit (39). Furthermore, it is preferable that before being introduced into the second post-treatment unit (50) described later, it be processed to pre-cool and pressurize at a preset temperature and pressure through the fourth pre-cooling cooler (39a), the fourth separator (40b), and the third compressor (41c). Additionally, it is preferable that the condensate be drained through the drain line provided at the bottom of the fourth separator (40b).

[0058] Accordingly, the multi-stage separation and compression unit (30) may be characterized by being provided in multiple locations to pre-cool and pressurize the exhaust gas to a preset temperature and pressure for the condensation and separation of the liquefied carbon dioxide through deep cooling heat exchange from the exhaust gas flowing into the deep cooling separation unit.

[0059] In addition, by adjusting the number of multi-stage separation and compression units (30) so that the exhaust gas is pre-cooled and pressurized to a preset temperature and pressure by the multi-stage separation and compression units (30), the condensation efficiency of the carbon dioxide can be significantly improved during the pre-cooling and deep cooling of the compressed exhaust gas by the cold heat generated during the re-gasification of the liquefied natural gas.

[0060] Specifically, in the past, the capture concentration of the carbon dioxide was only about 30%, but through the cooling and compression process of the multi-stage separation and compression unit (30), the capture concentration of the carbon dioxide can be raised to about 60%, thereby significantly increasing the net storage amount of the liquefied carbon dioxide.

[0061] In addition, the suitability for the downstream liquefaction process can be increased through the repeated cooling and compression process of the exhaust gas in the multi-stage separation and compression unit (30), thereby preventing freezing, plugging, and regime transfer in the deep cryogenic separation unit. Accordingly, the continuous operation functionality of the dual-fuel vessel can be enhanced.

[0062] In addition, the risk of freezing and hydrate can be significantly reduced by removing moisture in stages before deep cooling. Furthermore, an energy integrated design can be adopted so that the compression heat generated in the multi-stage separation compression unit (30) is not wasted but utilized as a heat source for the regasification of the liquefied natural gas, thereby allowing for excellent economic utilization.

[0063] Meanwhile, the exhaust gas, which has been pre-cooled and pressurized to a preset temperature and pressure by repeating it multiple times in the multi-stage separation and compression unit (30), can be introduced into the second post-treatment unit (50).

[0064] In addition, the second post-treatment unit (50) preferably further includes a pre-cooling cooler (50a) that cools the exhaust gas to a preset temperature once more before it is introduced into the deep cooling heat exchanger (61a). This can remove the compression heat generated during the pressurization process of the third compressor (41c) of the third compression unit (39) and induce the formation of condensate.

[0065] Accordingly, the exhaust gas cooled in the pre-cooling cooler (50a) can be introduced into the fifth separator (51b). Subsequently, it is preferable that the condensate be drained through the drain line provided at the bottom of the fifth separator (51b).

[0066] In addition, the second post-processing unit (50) preferably further includes a second separation control unit (55) which is a flow rate control means for stabilizing boundary conditions before being introduced into the deep cooling separation unit (60) and cooling, thereby lowering the sensitivity of the deep cooling condition and preventing transition to the vent surge section.

[0067] In detail, the second separation control unit (55) can stabilize the final flow rate, pressure, and temperature of the exhaust gas introduced into the deep cryogenic separation unit through a splitter or control valve. Therefore, by fixing or limiting the input boundary conditions, the stability of the deep cryogenic separation unit (60), which is sensitive to critical behavior, can be increased.

[0068] In addition, it is preferable to include a multi-stage separation and compression unit (30) connected in series to pre-cool and pressurize the exhaust gas to a preset temperature and pressure, so as to repeatedly cool the exhaust gas introduced from the first post-treatment unit (20), separate the condensate, and compress the exhaust gas to condense and separate the liquefied carbon dioxide through deep cooling.

[0069] Here, it is preferable to understand the deep cooling separation unit as a device that separates the condensed liquefied carbon dioxide from the exhaust gas introduced from the second post-treatment unit through heat exchange with the liquefied carbon dioxide deep cooling in the deep cooling heat exchanger (6) and drains it into the circulation tank.

[0070] Specifically, the deep cooling separation unit preferably includes a deep cooling cooler (61a) in which the liquefied carbon dioxide discharged from the circulation tank (2) and exchanged deep cooling heat with the regasification cold of the liquefied natural gas, and the exhaust gas introduced from the second post-treatment unit (50), exchange heat.

[0071] Here, the deep cooling cooler (61a) can facilitate the condensation of the exhaust gas by exchanging heat with the liquefied carbon dioxide that has undergone deep cooling heat exchange with the cold heat generated during the regasification process of the liquefied natural gas of the dual-fuel vessel, through the exhaust gas introduced from the second post-treatment unit (50). Accordingly, the burden on the deep cooling heat exchanger (6) can be reduced and the possibility of venting can be lowered.

[0072] Accordingly, by using the cold energy generated during the regasification process of the liquefied natural gas used in the above-mentioned dual-fuel vessel and connecting it directly to the liquefaction section, the condensation of the carbon dioxide present in the exhaust gas is caused. Accordingly, the waste of energy resources required to liquefy the exhaust gas and obtain the liquefied carbon dioxide is prevented, and the purity of the carbon dioxide-rich stream can be increased.

[0073] Additionally, the above-mentioned deep cooling separation unit (60) preferably further includes a gas-liquid separator (62) that separates the condensed liquid carbon dioxide from the exhaust gas cooled and discharged from the deep cooling cooler (61a) and drains it into the circulation tank (2).

[0074] In detail, the gas-liquid separator (62) can separate the liquefied carbon dioxide and the non-condensing gaseous phase (vent gas) generated after deep cooling. Furthermore, the non-condensing gaseous phase stream can be discharged or recirculated according to design selection, allowing for safe discharge treatment and appropriate gas concentration management.

[0075] In addition, the gas-liquid separator (62) may be further equipped with a dry drain line to discharge trace amounts of liquid and condensed components that may occur during operation, thereby increasing process reliability. Furthermore, the liquefied carbon dioxide condensed through the deep cold heat exchanger (6) and the deep cold separation unit (60) can be recirculated to the circulation tank (2) and introduced into the deep cold heat exchanger (6) by a liquefied carbon dioxide pump (2p) so that it can be heat exchanged during the regasification process of the liquefied natural gas.

[0076] Therefore, it is preferable that the above dual-fuel vessel includes a fuel tank (1) in which liquefied natural gas is stored as fuel for driving the main engine (3) and a circulation tank (2) in which liquefied carbon dioxide is stored.

[0077] In addition, it is preferable to include a deep cooling heat exchanger (6) that deep cools the liquefied carbon dioxide supplied from the circulation tank (2) using the regasification cold of the liquefied natural gas supplied from the fuel tank (1), and a first post-treatment unit (20) that post-treats the exhaust gas generated during combustion in the main engine (3). Furthermore, a multi-stage separation and compression unit (30) connected in series at multiple locations may be included to pre-cool and pressurize the exhaust gas introduced from the first post-treatment unit (20) to a preset temperature and pressure.

[0078] Furthermore, it is preferable to include a deep cooling separation unit comprising: a second post-treatment unit (50) for post-treating exhaust gas discharged from the multi-stage separation compression unit (30); a deep cooling cooler (61a) in which the liquefied carbon dioxide discharged from the circulation tank (2) and heat-exchanged in the deep cooling heat exchanger (6) by the re-gasification cold of the liquefied natural gas, and the exhaust gas introduced from the second post-treatment unit (50) undergo heat exchange; and a gas-liquid separator (62) for separating the liquefied carbon dioxide condensed from the exhaust gas cooled and discharged from the deep cooling cooler (61a) and draining it to the circulation tank.

[0079] Through this, the dual-fuel vessel reduces the emission of carbon dioxide from exhaust gases generated during operation using the carbon dioxide capture and storage system. Furthermore, by recirculating the captured liquefied carbon dioxide and using it to regasify the liquefied natural gas, energy savings can be achieved, and the dual-fuel vessel can be operated safely for a long period of time.

[0080] Meanwhile, terms such as "include," "compose," or "equip" described above, unless specifically stated otherwise, mean that the relevant component may be inherent; therefore, they should be interpreted as allowing for the inclusion of additional components rather than excluding them. All terms, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains, unless otherwise defined. Terms commonly used, such as those defined in advance, should be interpreted in accordance with their meaning in the context of the relevant technology and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this invention.

[0081] As explained above, the present invention is not limited to each of the embodiments described above, and modifications can be made by those skilled in the art without departing from the scope claimed in the claims of the present invention, and such modifications fall within the scope of the present invention. Explanation of the symbols

[0082] 1: Fuel tank 2: Circulation tank 20: 1st Post-processing Unit 30: Multi-stage Separation and Compression Unit 50: 2nd Post-processing Unit 60: Cryogenic Separation Unit

Claims

Claim 1 A fuel tank in which liquefied natural gas is stored as fuel for driving a main engine; a circulation tank in which liquefied carbon dioxide is stored; a deep cooling heat exchanger that deep cools the liquefied carbon dioxide supplied from the circulation tank using the regasification cold of the liquefied natural gas supplied from the fuel tank; a first post-treatment unit for post-treating exhaust gas generated during combustion in the main engine; a multi-stage separation and compression unit connected in series at multiple locations to repeatedly cool, separate condensate, and compress the exhaust gas introduced from the first post-treatment unit; and a second post-treatment unit for post-treating the exhaust gas discharged from the multi-stage separation and compression unit. The apparatus includes a deep cooling separation unit that separates condensed liquefied carbon dioxide from exhaust gas introduced from the second post-treatment unit through heat exchange with liquefied carbon dioxide deep-cooled in the deep cooling heat exchanger and drains it to the circulation tank, wherein the deep cooling separation unit includes a deep cooling cooler in which the liquefied carbon dioxide discharged from the circulation tank and deep cooling heat exchanged with the regasification cold of liquefied natural gas and the exhaust gas introduced from the second post-treatment unit exchanges heat, and a gas-liquid separator that separates the condensed liquefied carbon dioxide from the exhaust gas cooled and discharged from the deep cooling cooler and drains it to the circulation tank, and the liquefied carbon dioxide passing through the deep cooling heat exchanger and the deep cooling separation unit is recirculated to the circulation tank, and the multi-stage separation compression unit each includes a pre-cooling cooler that cools the exhaust gas by heat exchange with seawater, a separator that separates condensed water from the cooled exhaust gas, and pressurizes the exhaust gas from which the condensed water has been separated. A shipboard carbon dioxide capture and storage system characterized by having a plurality of locations, including a compressor for compressing, to pre-cool and pressurize the exhaust gas to a preset temperature and pressure for condensing and separating the liquefied carbon dioxide through deep cooling heat exchange from the exhaust gas flowing into the deep cooling separation unit. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 A carbon dioxide capture and storage system for ships according to claim 1, characterized in that the first post-treatment unit includes a dosing unit that doses exhaust gas exhausted from the main engine with ammonia gas. Claim 8 A carbon dioxide capture and storage system for ships according to claim 7, characterized in that the first post-treatment unit further includes a first separation control unit that cools the exhaust gas discharged from the dosing unit to pre-separate condensate and controls the flow rate of the exhaust gas. Claim 9 A carbon dioxide capture and storage system for ships according to claim 1, characterized in that the second post-treatment unit cools the exhaust gas introduced from the multi-stage separation and compression unit to subsequently separate condensate, and includes a flow control means for controlling the flow rate according to the pressure and temperature of the exhaust gas. Claim 10 delete

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