Carbon dioxide capture system for ship

Abstract

The carbon dioxide collection system for a ship according to the present invention comprises: a carbon dioxide collection device for removing carbon dioxide included in exhaust gas of a main engine; the low-temperature steam generator exchanges heat with exhaust gas of the auxiliary engine to generate steam; and a low-temperature steam supply line for supplying the steam generated by the low-temperature steam generator to the carbon dioxide capture device.

Description

TECHNICAL FIELD

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0030726, filed on March 8, 2023, Korean Patent Application No. 10-2023-0093363, filed on July 18, 2023, Korean Patent Application No. 10-2024-0032863, filed on March 7, 2024, and Korean Patent Application No. 10-2024-0032864, filed on March 7, 2024, the entire contents of which are incorporated by reference into the present specification. TECHNICAL FIELD

[0004] The present application relates to a carbon dioxide capture system for a ship, and more particularly, to a carbon dioxide capture system for a ship that generates low-temperature steam using waste heat of exhaust gas to heat an absorbent to a regeneration temperature and separate carbon dioxide. BACKGROUND

[0005] Maritime shipping accounts for about 80% of the global trade volume, and is the most economical and most common mode of transportation for long-distance cargo transportation. The engines of large cargo ships or cruise ships generally use heavy oil with a high sulfur content. When heavy oil with a high sulfur content as described above is used as fuel, a large amount of carbon dioxide (CO2) and sulfur dioxide (SO2) and the like are contained in exhaust gas. These pollutants are not only harmful to the human body, but also cause environmental pollution when the pollutants are emitted into the atmosphere without being filtered.

[0006] Accordingly, the United Nations has entrusted the International Maritime Organization (IMO) with regulating the exhaust gas emission of ships sailing in global waters, and the IMO is promoting various exhaust gas emission reduction measures with the goal of reducing the amount of environmental pollutants emitted from exhaust gas of ships by 40% compared to 2008 by 2030, and by 50% by 2050.

[0007] In Korea, in order to achieve the 2030 greenhouse gas emission reduction goal proposed by the IMO, a medium- and long-term roadmap has been established and research projects are being carried out. Accordingly, the shipping and shipbuilding industries are in need of solutions to reduce the emission of representative pollutants, carbon dioxide and sulfur dioxide, contained in exhaust gas in order to develop eco-friendly ships by actively developing technologies to reduce greenhouse gases generated by ships.

[0008] In order to remove carbon dioxide, exhaust gas passes through a carbon dioxide absorbent to remove carbon dioxide in the exhaust gas. Since the use of a new carbon dioxide absorbent each time increases the cost including disposal and transportation fees, the carbon dioxide absorbent can be regenerated and reused.

[0009] However, in the case of reusing the absorbent, the regeneration temperature of the absorbent is significantly different from the CO2 absorption temperature, resulting in additional CO2 emission during the absorbent regeneration heating process and an increase in the cost of heating the absorbent.

[0010] DISCLOSURE

[0011] TECHNICAL PROBLEM

[0012] An object of the present application is to provide a CO2 capture system for a ship, which can save fuel consumed for absorbent regeneration by generating low-temperature steam using waste heat of exhaust gas to increase the temperature of the absorbent to the regeneration temperature of the CO2 absorbent.

[0013] Another object of the present application is to improve the efficiency of the CO2 absorption process by lowering the temperature of the exhaust gas used in the CO2 absorption process.

[0014] Still another object of the present application is to provide a CO2 capture system for a ship, which is suitable for an amine-based absorbent by being able to supply low-temperature steam to a reboiler, thereby preventing the amine-based absorbent from deteriorating in performance due to high temperature.

[0015] Still another object of the present application is to provide a CO2 capture system for a ship, which saves fuel consumed for absorbent regeneration by generating low-temperature steam using waste heat of high-temperature exhaust gas from a methane oxidation catalyst reactor.

[0016] TECHNICAL SOLUTION

[0017] According to an embodiment of the present application, a CO2 capture system for a ship includes a CO2 capture device that removes CO2 contained in main engine exhaust gas, a low-temperature steam generator that generates steam by exchanging heat with exhaust gas of an auxiliary engine, and a low-temperature steam supply line that supplies steam generated from the low-temperature steam generator to the CO2 capture device.

[0018] According to an embodiment of the present application, the CO2 capture system can further include a methane oxidation catalyst reactor disposed between the auxiliary engine and the low-temperature steam generator to remove methane contained in the exhaust gas of the auxiliary engine, wherein the low-temperature steam generator can generate steam by exchanging heat with the exhaust gas passing through the methane oxidation catalyst reactor.

[0019] According to an embodiment of the present application, the low-temperature steam supply line can be disposed in a steam drum for separating liquid water in the steam.

[0020] According to an embodiment of the present application, the low-temperature steam generator can be a sub-economizer, and the steam can be low-temperature steam having a temperature condition of 100°C or higher and lower than 165°C under a pressure condition of lower than 6 bar gauge.

[0021] According to an embodiment of the present application, the carbon dioxide capturing system can include a first steam valve disposed on a low-temperature steam supply line and controlling an amount of steam supplied to the carbon dioxide capturing device.

[0022] According to an embodiment of the present application, the carbon dioxide capturing system can include a main economizer heat-exchanging with exhaust gas of a main engine to generate main steam, a boiler receiving the main steam preheated by the main economizer to generate high-temperature boiler steam, and a second steam valve disposed on a further supply line supplying the high-temperature boiler steam generated by the boiler to the carbon dioxide capturing device to convert the high-temperature boiler steam into low-temperature steam.

[0023] According to an embodiment of the present application, the carbon dioxide capturing system can further include a main economizer disposed on a main engine exhaust line connecting between the main engine and the carbon dioxide capturing device, and heat-exchanging with exhaust gas of the main engine to generate main steam, a second low-temperature steam generator disposed on the main engine exhaust line at a rear end of the main economizer, and heat-exchanging with the exhaust gas of the main engine passing through the main economizer to generate second steam, and a second low-temperature steam supply line supplying the second steam generated by the second low-temperature steam generator to the carbon dioxide capturing device.

[0024] According to an embodiment of the present application, the main engine or the auxiliary engine can use dual fuel.

[0025] According to an embodiment of the present application, a carbon dioxide capturing system for a ship includes a carbon dioxide capturing device removing carbon dioxide contained in exhaust gas of a main engine, a main economizer heat-exchanging with the exhaust gas of the main engine to generate main steam, a compound low-temperature steam generator receiving together the exhaust gas of the main engine passing through the main economizer and exhaust gas of an auxiliary engine to generate steam, and a low-temperature steam supply line supplying the steam generated by the compound low-temperature steam generator to the carbon dioxide capturing device.

[0026] According to an embodiment of the present application, the carbon dioxide capturing system can further include a boiler receiving the main steam preheated by the main economizer to generate high-temperature boiler steam, wherein at least a portion of boiler exhaust gas generated from the boiler can be supplied to the compound low-temperature steam generator.

[0027] According to an embodiment of the present invention, a carbon dioxide capturing system for a ship includes: a carbon dioxide capturing device that removes carbon dioxide contained in exhaust gas of a main engine; a low-temperature steam generator that exchanges heat with exhaust gas of an auxiliary engine to generate steam; and a low-temperature steam supply line that supplies steam generated from the low-temperature steam generator to the carbon dioxide capturing device, wherein at least a portion of the exhaust gas of the auxiliary engine passing through the low-temperature steam generator is joined to a main engine exhaust line connecting between the main engine and the carbon dioxide capturing device.

[0028] The carbon dioxide capturing system can further include: a main economizer disposed on the main engine exhaust line and exchanging heat with the exhaust gas of the main engine to generate main steam, wherein at least a portion of the exhaust gas of the auxiliary engine passing through the low-temperature steam generator can be joined to the main engine exhaust line at a rear end of the main economizer.

[0029] The carbon dioxide capturing system according to an embodiment of the present invention can further include: a boiler that receives the main steam preheated by the main economizer to generate high-temperature boiler steam, wherein at least a portion of boiler exhaust gas generated from the boiler can be joined to the main engine exhaust line at the rear end of the main economizer.

[0030] The carbon dioxide capturing system according to an embodiment of the present invention can include: a main economizer disposed on the main engine exhaust line and exchanging heat with the exhaust gas of the main engine to generate main steam; and a branch line branched from the main engine exhaust line at a rear end of the main economizer and connected to an auxiliary engine exhaust line connecting between the auxiliary engine and the low-temperature steam generator, wherein at least a portion of the exhaust gas of the main engine passing through the main economizer can be supplied to the low-temperature steam generator through the branch line.

[0031] The main engine or the auxiliary engine according to an embodiment of the present invention can use liquid fuel.

[0032] Advantageous effects

[0033] According to the present invention, low-temperature steam is generated using waste heat of exhaust gas to raise the temperature of a carbon dioxide absorbent to a regeneration temperature, thereby saving fuel consumed for absorbent regeneration.

[0034] In addition, carbon dioxide additionally generated for capturing carbon dioxide can be reduced.

[0035] In addition, by lowering the temperature of exhaust gas used in a carbon dioxide absorption process, the efficiency of the carbon dioxide absorption process can be improved.

[0036] In addition, by supplying low-pressure steam to a reboiler, absorbent performance deterioration due to high temperature can be prevented.

[0037] In addition, by utilizing waste heat from high-temperature exhaust gas generated by the methane oxidation catalyst reactor to generate low-temperature steam to raise the temperature of the absorbent to the regeneration temperature of the carbon dioxide absorbent, fuel consumed in regenerating the absorbent can be saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram illustrating a carbon dioxide capture system for a ship according to a first embodiment of the present invention.

[0039] Figure 2 A schematic diagram illustrating a carbon dioxide capture device for a ship according to a first embodiment of the present invention.

[0040] Figure 3 This is a table showing the loss rate according to the temperature of the amine-based absorbent.

[0041] Figure 4 Table illustrating saturated steam conditions.

[0042] Figure 5 A schematic diagram illustrating a steam-water circulation path of a carbon dioxide capture system for a ship according to a first embodiment of the present invention.

[0043] Figure 6 FIG2 is a schematic diagram illustrating a carbon dioxide capture system for a ship according to a second embodiment of the present invention.

[0044] Figure 7 A schematic diagram illustrating a carbon dioxide capture system for a ship according to a third embodiment of the present invention.

[0045] Figure 8 A schematic diagram illustrating a carbon dioxide capture system for a ship according to a fourth embodiment of the present invention.

[0046] Figure 9 A schematic diagram illustrating a carbon dioxide capture system for a ship according to a fifth embodiment of the present invention.

[0047] Figure 10 A schematic diagram illustrating a carbon dioxide capture system for a ship according to a sixth embodiment of the present invention.

[0048] Figure 11 A schematic diagram illustrating a carbon dioxide capture system for a ship according to one preferred embodiment of the present invention.

[0049] Figure 12 A schematic diagram illustrating a carbon dioxide capture system for a ship according to another preferred embodiment of the present invention.

[0050] Best Practice

[0051] Hereinafter, some embodiments of the present application will be described in detail with reference to the accompanying drawings. It should be noted that the same components are denoted by the same reference numerals wherever possible even though they are illustrated in different drawings. Also, in describing the embodiments of the present application, if it is determined that the detailed description of related known configurations or functions makes the understanding of the embodiments of the present application more difficult, the detailed description thereof will be omitted.

[0052] Also, in describing the components of the embodiments of the present application, terms such as first, second, A, B, (a), (b) can be used. These terms are used only to distinguish the components from other components, and do not limit the nature, order or sequence of the corresponding components. When a certain component is described as being "connected", "coupled" or "linked" to another component, it should be understood that the component can be directly connected or linked to the other component, but another component can also be "connected", "coupled" or "linked" between each component.

[0053] In the present specification, the front / rear, left / right, and up / down directions are mentioned for the convenience of description, and can be orthogonal directions to each other.

[0054] <First Embodiment>

[0055] Figure 1 To illustrate the exhaust gas treatment apparatus including a carbon dioxide capture system for a ship according to the first embodiment of the present application, a schematic diagram is shown. The carbon dioxide capture system for a ship includes a carbon dioxide capture device 140 that removes carbon dioxide contained in exhaust gas of a main engine 111, a low-temperature steam generator 150 that generates steam by heat exchange with exhaust gas of an auxiliary engine 121, and a low-temperature steam supply line 155 that supplies steam generated from the low-temperature steam generator 150 to the carbon dioxide capture device 140.

[0056] Exhaust gas emitted from the ship engine 111 and the ship engine 121 contains air pollutants such as nitrogen oxides (NOx), sulfur oxides (SOx), and carbon dioxide (CO2) and greenhouse gases. To reduce the pollutants in the exhaust gas, there is a method of reducing the sulfur content in the fuel based on the use of alternative fuels such as methanol, liquefied natural gas (LNG), and emulsified fuel instead of diesel as a pretreatment method to reduce nitrogen oxides, sulfur oxides, and particulate matter (PM) emissions.

[0057] Each pollutant can be removed by a post-treatment method that removes each pollutant through a process. The carbon dioxide capture system for a ship can include a nitrogen oxide absorption unit (not illustrated) for removing nitrogen oxides, a sulfur oxide removal unit (not illustrated) for removing sulfur oxides (SOx), and the carbon dioxide capture device 140 for removing carbon dioxide.

[0058] The generated pollutants can vary depending on the type of fuel supplied to the ship engine 111 and the ship engine 121, and the entire nitrogen oxide absorbing unit, and the sulfur oxide absorbing unit and the carbon dioxide capturing device 140 can be included or can be partially omitted.

[0059] The nitrogen oxide absorbing unit can remove nitrogen oxides in the exhaust gas by supplying an absorbent such as ammonia (NH3) into the chamber. Figure 1 The nitrogen oxide absorbing unit is not illustrated, but the exhaust gas passing through the nitrogen oxide removing unit can be supplied to the sulfur oxide removing unit.

[0060] Sulfur oxide removing units for reducing industrial emissions of sulfur oxides (SOx) have been used on land for about 100 years, but have been installed on ships only about 30 years ago. In the case of ships, there are differences from land scrubbers due to space limitations.

[0061] Sulfur oxides (SOx) in the exhaust gas are acidic substances, and thus an alkaline substance can be used as a sulfur oxide absorbent to neutralize the sulfur oxides (SOx), or seawater, which is a natural alkaline substance, can be used as a sulfur oxide absorbent. Seawater is weakly alkaline due to bicarbonate in seawater, and bicarbonate-containing seawater has a sulfur oxide (SOx) solubility about 2 to 3 times higher than fresh water.

[0062] Seawater (SW) is introduced into the ship and sprayed into the chamber of the sulfur oxide removing unit to which the exhaust gas is supplied. The seawater reacts with sulfur oxides such as sulfur dioxide (SO2) or sulfur trioxide (SO3) in the exhaust gas and is converted into an aqueous solution of sulfurous acid (H2SO3) or sulfuric acid (H2SO4).

[0063] The water discharged from the sulfur oxide removing unit contains sulfuric acid or sulfurous acid and thus has high acidity and contains pollutants other than sulfuric acid and sulfurous acid, and thus a water treatment system can also be included to control the acidity and remove the pollutants before the discharged water is discharged into the sea.

[0064] On the other hand, carbon dioxide (CO2) is not dissolved in seawater compared to sulfuric acid, and thus passes through the sulfur oxide removing unit, but the exhaust gas still has a high carbon dioxide (CO2) content and thus needs to be removed using a carbon dioxide absorbent.

[0065] To remove carbon dioxide, a carbon dioxide absorbent that reacts with carbon dioxide is required. The carbon dioxide absorbent includes an amino acid having an amine group, an amino acid mimic containing an amine group and a carboxyl group, an alkali metal salt thereof, etc. When these substances are dissolved in water under the action of a catalyst and pass through carbon dioxide, the substances can bind with carbon dioxide to generate byproducts.

[0066] However, separate storage space and processing costs are required to store or process the absorbent that has captured the carbon dioxide. The absorbent can be regenerated and recycled, but since the regeneration temperature of the absorbent is very different from the absorption temperature of the carbon dioxide, heat is required to regenerate the absorbent. When the fuel of the boiler is used for the heat of the absorbent regeneration, there is a problem of additional carbon dioxide generation and an increase in the cost of absorbent regeneration.

[0067] Referring to Figure 2 A carbon dioxide capturing device 140 according to the present application is described. The carbon dioxide capturing device 140 can include an exhaust gas cooler 148 to cool the exhaust gas to an absorption temperature required for carbon dioxide absorption, a carbon dioxide absorption chamber 146 to which carbon dioxide absorbent from an absorption tank 149 and the exhaust gas temperature-controlled by the exhaust gas cooler 148 are supplied, an absorbent regeneration chamber 141 to regenerate the absorbent, a reboiler 142 to provide heat for the absorbent regeneration, and an exhaust gas scrubbing unit 147 to scrub the exhaust gas discharged from the carbon dioxide absorption chamber 146.

[0068] The exhaust gas cooler 148 can also be provided in the carbon dioxide capturing device 140 separately from Figure 1 the pre-cooler 115 as shown. Alternatively, only one of the pre-cooler 115 and the exhaust gas cooler 148 can be provided. To improve the carbon dioxide absorption efficiency, the exhaust gas supplied along a main engine exhaust line ML connected between the main engine 111 and the carbon dioxide capturing device 140 can be introduced into the exhaust gas cooler 148 and adjusted to a required absorption temperature (e.g., about 30 to 40°C for an amine-based absorbent) according to the type of carbon dioxide absorbent. However, in some cases, only one of the pre-cooler 115 and the exhaust gas cooler 148 can be present, and thus the number of coolers is not limited.

[0069] The carbon dioxide absorption chamber 146 includes an exhaust gas injection port to which the exhaust gas containing carbon dioxide is introduced, an absorbent supply unit to supply the regenerated carbon dioxide absorbent, a discharge port to discharge the exhaust absorbent having absorbed the carbon dioxide and introduce it into the absorbent regeneration chamber 141, and an exhaust gas outlet to discharge the exhaust gas from which the carbon dioxide is removed.

[0070] The exhaust gas injection port is located at a lower end portion of a side surface of the carbon dioxide absorption chamber 146, and the exhaust gas outlet is located at an upper side such that the exhaust gas can move from the lower portion to the upper portion of the carbon dioxide absorption chamber 146.

[0071] The carbon dioxide absorption chamber 146 can include an injection unit to inject the absorbent into the inside. The injection unit includes a nozzle to inject the absorbent in the form of fine particles and supply the absorbent into the exhaust gas inside the carbon dioxide absorption chamber 146.

[0072] The absorbent can be an amine-based absorbent, and can include at least one of monoethanolamine (MEA), methyldiethanolamine (MDEA), diethanolamine (DEA), and diglycolamine (DGA). Only representative amine-based absorbents are mentioned, and other types of amine-based absorbents can also be used.

[0073] The amine-based absorbent has excellent carbon dioxide absorption at a temperature range of about 30°C to 40°C. Thus, it is desirable to maintain the temperature (absorption temperature) within the carbon dioxide absorption chamber 146 of the carbon dioxide capturing device 140 at about 30°C to 40°C. To this end, the gas cooler 148 described above can be used.

[0074] The injection unit can be provided at the upper portion of the carbon dioxide absorption chamber 146. By injecting the absorbent from the upper portion of the carbon dioxide absorption chamber 146, the area of contact with the exhaust gas can be maximized.

[0075] After the carbon dioxide is removed in the absorbent regeneration chamber 141, the exhaust gas from which the carbon dioxide has been removed can be discharged into the atmosphere after being washed again of contaminants with water in the exhaust gas washing unit 147.

[0076] In addition, the carbon dioxide in the exhaust gas can be supplied to the absorbent regeneration chamber 141 through a drain port located at the lower portion of the carbon dioxide absorption chamber 146, while being dissolved in the absorbent.

[0077] To separate the carbon dioxide in the absorbent, the absorbent regeneration chamber 141 heats the absorbent at a high temperature to evaporate and separate the carbon dioxide in the absorbent. The regeneration temperature at which the carbon dioxide is separated in the absorbent regeneration chamber 141 is about 100°C to 120°C, which is 60°C or more different from the absorption temperature (30°C to 40°C). Thus, external heating is required for the regeneration of the absorbent, and the absorbent can be heated by the reboiler 142. However, additional carbon dioxide is generated during the combustion of the reboiler 142, and problems such as deterioration of the overall system efficiency can occur depending on the amount of use of the reboiler 142.

[0078] To compensate for the difference between the absorption temperature and the regeneration temperature, the temperature difference between the two chambers 146 and 141 can be compensated for by the absorbent heat exchanger 145, which performs heat exchange between the absorbent recovery line 143, which absorbs the carbon dioxide in the carbon dioxide absorption chamber 146 and supplies the carbon dioxide to the absorbent regeneration chamber 141, and the absorbent supply line 144, which supplies the absorbent regenerated in the absorbent regeneration chamber 141 to the carbon dioxide absorption chamber 146.

[0079] That is, the temperature can be compensated for by heat exchange between the low-temperature absorbent passing through the absorbent recovery line 143 and the high-temperature absorbent passing through the absorbent supply line 144, and the temperature of the absorbent supplied to the absorbent regeneration chamber 141 can be raised to a level of 70°C to 90°C.

[0080] However, even though heat exchange is performed in the absorbent heat exchanger 145, it is difficult to satisfy the regeneration temperature required for the absorbent regeneration chamber 141, and thus the absorbent regeneration chamber 141 can use a reboiler 142 to raise the absorbent to the regeneration temperature. The reboiler 142 uses steam to heat the absorbent to the regeneration temperature. A saturated steam state is used to maximize steam energy. The steam supplied to the reboiler 142 can use steam higher than the regeneration temperature, so that the absorbent of 70°C to 90°C supplied to the absorbent regeneration chamber 141 can be raised to the regeneration temperature of 100°C to 120°C. In consideration of temperature raising efficiency, the higher the steam temperature, the faster the temperature of the absorbent can be raised.

[0081] However, an amine-based absorbent is denatured at a high temperature, and thus is difficult to reuse after a certain period of time and thus needs to be replaced. Thus, when the steam temperature heated in the reboiler 142 is too high, the modification of the absorbent can be accelerated. Figure 3 A graph illustrating the rate at which an amine-based absorbent is denatured and lost according to temperature. The absorbent can include components such as monoethanolamine (MEA), methyldiethanolamine (MDEA), diethanolamine (DEA), and diglycolamine (DGA), and exhibits different characteristics according to the ratio.

[0082] The loss rate varies according to the type and mixing ratio of the absorbent, but the loss occurs at about 120°C to 150°C, and the loss of most absorbents significantly increases at 150°C to 175°C or higher than 175°C.

[0083] Thus, in order to absorbent heating efficiency and prevent absorbent loss, it is preferable to use low-temperature steam of 100°C or higher and lower than 165°C as the temperature of the absorbent supplied to the reboiler 142.

[0084] Figure 4 A table illustrating the saturated steam condition, and it can be confirmed that the temperature at which saturated steam is formed at a certain pressure. In order to form saturated steam in the above-mentioned regeneration temperature range, low-temperature steam having a temperature range of 100°C or higher and lower than 165°C can be generated at a pressure condition of lower than 6 barg. Preferably, saturated steam L having a temperature range of 134°C to 152°C at a pressure of 2 barg to 4 barg can be used.

[0085] The higher the steam temperature, the greater the energy storage capacity, so a small amount of steam can deliver a large amount of energy and the pipe size can be reduced. Therefore, steam at 165°C or higher and 6 bar gauge or higher is generally used as the steam provided by a marine boiler, and since it is a relatively high temperature compared to the steam required for absorbent regeneration, it is referred to as high-temperature steam. In addition, the steam required for absorbent regeneration is generally at a lower temperature compared to the steam provided by a marine boiler, so it is referred to as low-temperature steam.

[0086] However, when absorbent regeneration is performed using high-temperature steam generated by the existing boiler, the absorbent can be exposed to a temperature of 165°C or higher, which can increase the loss rate of the absorbent. The present invention can utilize the waste heat of the exhaust gas and generate low-temperature steam by reducing the loss rate of the absorbent to extend the service life of the absorbent, and supply the low-temperature steam to the reboiler 142 of the carbon dioxide capture device 140 through the low-temperature steam supply line 155. The low-temperature steam supply line 155 is defined as a line connecting the low-temperature steam generator 150 to the reboiler 142 of the carbon dioxide capture device 140.

[0087] To improve the efficiency of the absorbent regeneration chamber 141, at least part of the absorbent containing carbon dioxide introduced from the upper portion of the absorbent regeneration chamber 141 can be branched off through the regeneration branch line 131, and after heat exchange with the relatively high-temperature regenerated absorbent in the absorbent supply line 144 in the regeneration heat exchanger 132, it can be supplied to the absorbent regeneration chamber 141 again through the resupply line 133.

[0088] The carbon dioxide gas separated in the absorbent regeneration chamber 141 can be stored or used at a necessary site after being treated to be liquefied.

[0089] Referring back to Figure 1 , steam is generated by heat exchange with the exhaust gas of the auxiliary engine 121 in the low-temperature steam generator 150, and the steam generated from the low-temperature steam generator 150 is supplied to the reboiler 142 of the carbon dioxide capture device 140 through the low-temperature steam supply line 155. The exhaust gas temperature of the main engine 111 is about 250°C, and the exhaust gas temperature of the auxiliary engine 121 is 300°C to 400°C, so it is most ideal to utilize the waste heat of the exhaust gas of the auxiliary engine 121 in terms of energy efficiency. Therefore, the low-temperature steam generator 150 uses the exhaust gas of the auxiliary engine 121.

[0090] The low-temperature steam generator 150 can be a sub-economizer 152 that generates low-temperature steam using the waste heat of the exhaust gas of the auxiliary engine 121.

[0091] The main engine 111 is a main power source for the operation of the ship, and the auxiliary engine 121 is an electric power generation engine independent of the main engine 111 and provides electric power to the ship in addition to the main engine. Since the auxiliary engine 121 has a smaller exhaust emission amount than the main engine 111, depending on the fuel type, an exhaust gas treatment process for removing carbon dioxide or sulfur dioxide or the like from the exhaust gas can be omitted. For example, in the case of a ship using LNG as fuel or a dual fuel (gasoline / diesel) ship, the exhaust gas of the auxiliary engine 121 can be directly discharged into the atmosphere independent of the exhaust gas of the main engine 111.

[0092] The exhaust waste heat of the auxiliary engine 121 can be used to generate low-temperature steam from the sub-economizer 152. The low-temperature steam generated from the sub-economizer 152 can have a temperature range of 100°C or higher and lower than 165°C at a pressure lower than 6 bar gauge. Figure 1 It is described that the exhaust gas generated from the auxiliary engine 121 is branched from the exhaust emission pipe 123 and supplied to the sub-economizer 152 through the exhaust gas supply pipe 124, but the sub-economizer 152 can be provided on the exhaust emission pipe 123, and thus is not limited to Figure 1 It is described that the exhaust gas generated from the auxiliary engine 121 is branched from the exhaust emission pipe 123 and supplied to the sub-economizer 152 through the exhaust gas supply pipe 124, but the sub-economizer 152 can be provided on the exhaust emission pipe 123, and thus is not limited to

[0093] The low-temperature steam generated from the sub-economizer 152 can pass through the steam tank 153. Since the efficiency is reduced when water is mixed in the steam, liquid water can be removed from the steam tank 153, and only the saturated steam after the water is removed can be supplied to the reboiler 142. The steam tank 153 can be provided on the low-temperature steam supply line 155.

[0094] By utilizing the waste heat of the exhaust gas generated when the main engine 111 is driven, high-temperature steam can be generated from the main economizer 112 and the boiler 154. The main economizer 112 raises the temperature of water by utilizing the waste heat of the main engine 111, and the boiler 154 can generate high-temperature steam by using steam / water preheated in the main economizer 112. The high-temperature steam generated from the boiler 154 can be supplied to other demand sources of the ship. In addition, the high-temperature steam of the boiler 154 can also be converted into low-temperature steam by reducing the temperature and supplied to the reboiler 142. This will be described later with reference to the second steam valve V2.

[0095] After the high-temperature steam is generated from the main economizer 112, the exhaust gas discharged through the exhaust emission pipe 114 is still high in temperature, and thus it can be cooled to the absorption temperature in the pre-cooler 115 and then supplied to the carbon dioxide capture device 140. The higher the temperature of the exhaust gas supplied to the pre-cooler 115, the more heat is wasted and the larger the amount of seawater that needs to be supplied, which also causes energy loss, and thus the recovery method thereof will be described later.

[0096] Figure 1Exhaust gas generated from the main engine 111 is branched from the exhaust gas discharge pipe 114 and supplied to the carbon dioxide capturing device 140 through the exhaust gas supply pipe 119. However, the carbon dioxide capturing device 140 can be provided on the exhaust gas discharge pipe 114, and thus is not limited to Figure 1 the matters shown.

[0097] The first embodiment can be applied to a case where the main engine 111 or the auxiliary engine 121 uses dual fuel (gasoline / diesel), but is not limited thereto. In the first embodiment, low-temperature steam can be generated by utilizing exhaust gas waste heat of the auxiliary engine 121 and used for the absorbent regeneration. In the first embodiment, at least a part of the main engine 111 exhaust gas can be supplied to the carbon dioxide capturing device 140.

[0098] Figure 5 A schematic diagram of a steam-water circulation path for a carbon dioxide capturing system for a ship according to the first embodiment of the present application is illustrated. The steam-water circulation path can be equally applied to all other embodiments.

[0099] The heat capacity of the exhaust gas generated from the auxiliary engine 121 varies depending on the atmospheric temperature, fuel properties, and the amount of electricity used according to the operating conditions of the ship.

[0100] The amount of steam generated from the auxiliary economizer 152 can be greater than the amount of steam required for the reboiler 142. To prevent excess steam supply, a first steam valve V1 can be included to bypass and discharge the excess steam supplied from the steam tank 153 to the reboiler 142. The first steam valve V1 is provided on the low-temperature steam supply line 155 and can control the amount of steam supplied to the reboiler 142 of the carbon dioxide capturing device 140. The first steam valve V1 can be in the form of a three-way valve. The first steam valve can be disposed at a position as Figure 1 illustrated, and the disposition position is not limited. The excess steam generated from the auxiliary economizer 152 is supplied to the drain cooler 157 to be liquefied and stored in the feedback water tank 158 through the first steam valve V1, and then can be supplied to the boiler 154 or the steam tank 153 when needed. In addition, the excess steam generated from the auxiliary economizer 152 can be supplied to and used by other demand sources.

[0101] Meanwhile, when the amount of steam generated from the sub-economizer 152 is less than the required heat capacity of the reboiler 142, the boiler 154 can be used to additionally supply steam. The boiler 154 can be a dedicated boiler 154 for the reboiler 142, or a boiler 154 that supplies high-temperature steam for other equipment of the ship. The boiler 154 can generate steam by burning additional fuel independently of the engine. Also, the boiler 154 can generate high-temperature boiler steam by receiving main steam preheated from the main economizer 112. However, as described above, when high-temperature steam of 165°C or higher is used for absorbent regeneration, the absorbent loss rate can increase, and thus a second steam valve V2 for converting high-temperature boiler steam into low-temperature steam can be included.

[0102] The high-temperature boiler steam of 165°C or higher generated from the boiler 154 is converted into low-temperature steam having a temperature range of 100°C or higher and lower than 165°C at a pressure condition of less than 6 bar gauge through the second steam valve V2. Preferably, it is converted into low-temperature steam having a temperature range of 134°C to 152°C at a pressure of 2 bar gauge to 4 bar gauge.

[0103] In Figure 5 In the above-described embodiment, the second steam valve V2 is provided on an additional supply line 159 connecting the boiler 154 to the low-temperature steam supply line 155, but is not limited thereto. For example, the additional supply line 159 can be defined as a pipe directly connecting the boiler 154 of the carbon dioxide capture device 140 to the reboiler 142. That is, the low-temperature steam supply line 155 passing through the sub-economizer 152 and the additional supply line 159 passing through the boiler 154 can be connected to the reboiler 142, respectively, or can be merged or connected as one line.

[0104] In addition, when the amount of steam generated from the boiler 154 and converted into low-temperature steam is greater than the amount of steam required for the reboiler 142, the excess steam generated from the boiler 154 can be discharged to the drain cooler 157 through the third steam valve V3. In addition, the excess steam generated from the boiler 154 can also be supplied to and used by other demand sources.

[0105] The low-temperature steam supplied to the absorbent from the reboiler 142 can be liquefied into water, and a water recovery line 156 for recovering the liquefied water can be included. Referring to Figure 5 The steam-water circulation path, the excess steam generated from the sub-economizer 152 can be supplied to the drain cooler 157 and liquefied through the first steam valve V1, and the excess steam generated from the boiler 154 can be supplied to the drain cooler 157 and liquefied through the third steam valve V3. The water stored in the feedback water tank 158 can be supplied to the boiler 154 or the steam tank 153 as needed.

[0106] The amount of water supplied from the feedback water tank 158 to the steam tank 153 and the boiler 154 can be controlled by the water pumps P1 and P2, respectively. To ensure stable water supply to the main economizer 112 and the auxiliary economizer 152, water can be supplied by the circulation pumps P3 and P4. Water supplied to the steam tank 153 or separated from the steam can be supplied to the auxiliary economizer 152 by the first circulation pump P3. Water of the boiler 154 can be supplied to the main economizer 112 by the second circulation pump P4.

[0107] Instead of directly supplying water from the feedback water tank 158 to the auxiliary economizer 152 or the main economizer 112, water is supplied to the steam tank 153 or the boiler 154 to maintain a constant water level of the steam tank 153 and the boiler 154, thereby enabling stable generation of steam. In addition, the amount of water supplied can be adjusted according to a change in the available heat capacity in the exhaust gas, thereby generating a maximum amount of steam.

[0108] However, if necessary, it can also be configured to directly supply water from the feedback water tank 158 to the auxiliary economizer 152 or the main economizer 112.

[0109] A water supply valve V4 can be included, which adjusts the amount of water delivered to each of the steam tank 153 or the boiler 154 according to the available heat capacity in the exhaust gas of the auxiliary engine 121. The water supply valve V4 can supply recovered water to the steam tank 153 or the boiler 154 according to the available heat capacity of the main economizer 112 and the auxiliary economizer 152. Since there can be some loss in the steam-water circulation path, a makeup water valve can be included, which additionally supplies water from the outside to the feedback water tank to maintain a stable water level.

[0110] <Second Embodiment>

[0111] Figure 6 A carbon dioxide capture system for a ship according to a second embodiment of the present application is described. The carbon dioxide capture system for a ship includes a carbon dioxide capture device 140 that removes carbon dioxide contained in exhaust gas of a main engine 111, a low-temperature steam generator 150 that generates steam by heat exchange with exhaust gas of an auxiliary engine 121, a low-temperature steam supply line 155 that supplies steam generated from the low-temperature steam generator 150 to the carbon dioxide capture device 140, a main economizer 112 that is provided on a main engine exhaust line ML connecting the main engine 111 and the carbon dioxide capture device 140, generates main steam by heat exchange with exhaust gas of the main engine 111, a second low-temperature steam generator 160 that is provided on the main engine exhaust line ML at a rear end of the main economizer 112, and generates second steam by heat exchange with exhaust gas of the main engine passing through the main economizer 112, and a second low-temperature steam supply line 161 that supplies the second steam generated from the second low-temperature steam generator to the carbon dioxide capture device 140.

[0112] After high-temperature steam is generated from the main economizer 112, the temperature of the exhaust gas discharged through the exhaust gas discharge pipe 114 is still high, and thus the exhaust gas needs to be cooled to an absorption temperature required by the carbon dioxide capturing device 140 in the pre-cooler 115 and then supplied to the carbon dioxide capturing device 140. The higher the temperature of the exhaust gas supplied to the pre-cooler 115, the more heat is wasted, and the more seawater is required to be supplied, which also causes energy loss.

[0113] The carbon dioxide capturing system according to the second embodiment provides a separate second low-temperature steam generator 160 at the rear end of the main economizer 112 to further reduce the temperature of the exhaust gas supplied to the pre-cooler 115, and thus the exhaust gas waste heat of the main engine passing through the main economizer 112 can be reused in the second low-temperature steam generator 160. Accordingly, the yield of low-temperature steam can be increased, and the temperature of the exhaust gas of the main engine supplied to the pre-cooler 115 can be reduced. Since the temperature of the exhaust gas of the main engine introduced into the pre-cooler 115 is reduced, the amount of cooling water (seawater) supplied to the pre-cooler 115 can be reduced, thereby improving the efficiency of the system.

[0114] The second low-temperature steam generator 160 can be a second economizer, and the low-temperature steam generated from the second low-temperature steam generator 160 can be supplied to the reboiler 142 of the carbon dioxide capturing device 140 through a second low-temperature steam supply line 161. As Figure 6 shown, the second low-temperature steam supply line 161 can be connected with the low-temperature steam supply line 155, or can be separately supplied to the reboiler 142 of the carbon dioxide capturing device 140.

[0115] Further, the carbon dioxide capturing system according to the second embodiment can further include a third low-temperature steam generator 162 that generates third steam by heat exchange with the boiler exhaust gas generated from the boiler 154, and a third low-temperature steam supply line 163 that supplies the third steam generated from the third low-temperature steam generator 162 to the carbon dioxide capturing device 140. In the second embodiment, the separate third low-temperature steam generator 162 is provided so that the waste heat of the boiler exhaust gas generated from the boiler 154 can further increase the yield of low-temperature steam. The third low-temperature steam generator 162 can be a third sub-economizer, and the low-temperature steam generated from the third low-temperature steam generator 162 can be supplied to the reboiler 142 of the carbon dioxide capturing device 140 through the third low-temperature steam supply line 163. As Figure 6 shown, the third low-temperature steam supply line 163 can be connected with the low-temperature steam supply line 155, or can be separately supplied to the reboiler 142 of the carbon dioxide capturing device 140.

[0116] The second embodiment can be applied to a case where the main engine 111 and the auxiliary engine 121 use dual fuel (gasoline / diesel), but is not limited thereto. In the second embodiment, in addition to the exhaust heat of the exhaust gas of the auxiliary engine 121, the exhaust heat of the exhaust gas of the main engine 111 and the boiler 154 can also be used, and low-temperature steam can be generated by each low-temperature steam generator and used for the absorbent regeneration. In the second embodiment, at least a part of the exhaust gas of the main engine 111 can be supplied to the carbon dioxide capturing device 140.

[0117] <Third Embodiment>

[0118] Figure 7 A carbon dioxide capturing system for a ship according to a third embodiment of the present application is described. The carbon dioxide capturing system for a ship includes a carbon dioxide capturing device 140 that removes carbon dioxide contained in the exhaust gas of a main engine 111, a methane oxidation catalyst reactor 180 that removes methane contained in the exhaust gas of an auxiliary engine 121, a low-temperature steam generator 150 that is provided at a rear end of the methane oxidation catalyst reactor 180 and exchanges heat with the exhaust gas passing through the methane oxidation catalyst reactor 180 to generate steam, and a low-temperature steam supply line 155 that supplies the steam generated from the low-temperature steam generator 150 to the carbon dioxide capturing device 140.

[0119] The third embodiment is shown in FIG. 3, in which the methane oxidation catalyst reactor 180 is additionally provided between the auxiliary engine 121 and the low-temperature steam generator 150 in the first embodiment, but the methane oxidation catalyst reactor 180 can also be additionally provided between the auxiliary engine 121 and the low-temperature steam generator 150 in the same manner as in the second embodiment. Figure 7 The methane oxidation catalyst reactor 180 can be provided on the exhaust gas line of the auxiliary engine 121, and the carbon dioxide capturing device 140 can be provided on the exhaust gas line of the main engine 111 in the third embodiment. Since the methane oxidation catalyst is expensive, it is used only for a low-pressure auxiliary engine (a power generation engine) and not for a high-pressure main engine (a propulsion engine), thereby reducing the cost of the methane oxidation catalyst. Figure 6

[0120] In addition, in the third embodiment, the methane oxidation catalyst reactor 180 can be provided on the exhaust gas line of the auxiliary engine 121, and the carbon dioxide capturing device 140 can be provided on the exhaust gas line of the main engine 111. Since the methane oxidation catalyst is expensive, it is used only for a low-pressure auxiliary engine (a power generation engine) and not for a high-pressure main engine (a propulsion engine), thereby reducing the cost of the methane oxidation catalyst.

[0121] ​The third embodiment can be applied to a case where the main engine 111 and the auxiliary engine 121 use dual fuel (gas oil / diesel oil), but is not limited thereto. The third embodiment uses the exhaust gas waste heat of the auxiliary engine 121, but by utilizing the high-temperature exhaust gas waste heat of the methane oxidation catalyst reactor 180, it is possible to provide a sufficient heat source for generating low-temperature steam. In the third embodiment, at least part of the exhaust gas of the main engine 111 can be supplied to the carbon dioxide capturing device 140.

[0122] <Fourth Embodiment>

[0123] Figure 8 A carbon dioxide capturing system for a ship according to the fourth embodiment of the present application is described. The carbon dioxide capturing system for a ship includes a carbon dioxide capturing device 140 that removes carbon dioxide contained in the exhaust gas of a main engine 111, a main economizer 112 that generates main steam by heat exchange with the exhaust gas of the main engine 111, a compound low-temperature steam generator 170 that receives together the main engine exhaust gas through the main economizer 112 and the exhaust gas of an auxiliary engine 121 to generate steam, and a low-temperature steam supply line 155 that supplies the steam generated from the compound low-temperature steam generator 170 to the carbon dioxide capturing device 140.

[0124] In the fourth embodiment, the main engine exhaust gas through the main economizer 112 and the auxiliary engine 121 exhaust gas can be supplied together to the compound low-temperature steam generator 170 to generate low-temperature steam. The compound low-temperature steam generator 170 can be a compound sub-economizer. The exhaust gas waste heat of the main engine discharged from the main economizer 112 can be reused in the compound low-temperature steam generator 170 to generate low-temperature steam together with the exhaust gas of the auxiliary engine 121. Therefore, the amount of low-temperature steam generated can be increased compared to the case where the low-temperature steam is generated only with the exhaust gas of the auxiliary engine 121.

[0125] Further, in the fourth embodiment, at least part of the boiler exhaust gas generated from the boiler 154 can be supplied to the compound low-temperature steam generator 170. Therefore, the exhaust gas waste heat discharged from the boiler 154 can also be used to generate low-temperature steam in the compound low-temperature steam generator 170.

[0126] The fourth embodiment can be applied to a case where the main engine 111 and the auxiliary engine 121 use dual fuel (gas oil / diesel oil), but is not limited thereto. In the fourth embodiment, the exhaust gas waste heat of the main engine 111 and the boiler 154 can make low-temperature steam and regenerate the absorbent through a single compound low-temperature steam generator 170 in addition to the exhaust gas of the auxiliary engine 121. In the fourth embodiment, at least part of the exhaust gas of the main engine 111 can be supplied to the carbon dioxide capturing device 140.

[0127] <Fifth Embodiment>

[0128] Figure 9 A carbon dioxide capture system for a ship according to the fifth embodiment of the present application is described. The carbon dioxide capture system for a ship includes a carbon dioxide capture device 140 which removes carbon dioxide contained in exhaust gas of a main engine 111, a low-temperature steam generator 150 which generates steam by heat exchange with exhaust gas of an auxiliary engine 121, and a low-temperature steam supply line 155 which supplies steam generated from the low-temperature steam generator 150 to the carbon dioxide capture device 140, wherein at least a portion of exhaust gas of the auxiliary engine of the low-temperature steam generator 150 can be joined with a main engine exhaust line ML connecting between the main engine 111 and the carbon dioxide capture device 140.

[0129] Further, the carbon dioxide capture system for a ship further includes a main economizer 112 provided on the main engine exhaust line ML which generates main steam by heat exchange with exhaust gas of the main engine, and at least a portion of exhaust gas of the auxiliary engine of the low-temperature steam generator 150 can be joined with the main engine exhaust line ML at a rear end of the main economizer 112. The joining position of the exhaust gas of the auxiliary engine of the low-temperature steam generator 150 is specified.

[0130] In the fifth embodiment, since exhaust gas of the auxiliary engine 121 contains more harmful substances than LNG, it can be combined with exhaust gas of the main engine 111 to remove carbon dioxide, and then discharged. The exhaust gas through the low-temperature steam generator 150 contains different SOx and the like components according to the fuel type, and when the discharge standard is not satisfied, it can be supplied to the pre-cooler 115 by joining with the main engine exhaust line ML to be discharged into the atmosphere through a sulfuric acid removal unit or a carbon dioxide removal unit.

[0131] In this case, the exhaust gas through the low-temperature steam generator 150 can be combined with the exhaust gas through the main economizer 112 and supplied to the carbon dioxide capture device 140. That is, at least a portion of the exhaust gas of the auxiliary engine of the low-temperature steam generator 150 can be joined with the main engine exhaust line ML and supplied to the carbon dioxide capture device 140. Accordingly, in the fifth embodiment, at least a portion of carbon dioxide contained in the exhaust gas of not only the main engine 111 but also the auxiliary engine 121 can be removed, thereby satisfying a required carbon dioxide discharge standard.

[0132] Further, at least part of the boiler exhaust gas generated from the boiler 154 can be joined with the main engine exhaust line ML at the rear end of the main economizer 112. As described in the first embodiment, the boiler 154 can generate steam by burning additional fuel independently of the engine, and thus at least part of the boiler exhaust gas generated at this time can be joined with the main engine exhaust line ML and supplied to the carbon dioxide capture device 140. Accordingly, in the case of the fifth embodiment, at least part of the carbon dioxide contained in the exhaust gas discharged from the main engine 111 and the auxiliary engine 121 and the boiler 154 can be removed to satisfy the required carbon dioxide emission standard.

[0133] In addition, the second low-temperature steam generator 160 of the second embodiment can be configured to be provided on the main engine exhaust line ML at the rear end of the main economizer 112 so as to generate second steam by heat exchange with the main engine exhaust gas passing through the main economizer 112. Further, the third low-temperature steam generator 162 of the second embodiment can be configured to generate third steam by heat exchange with the boiler exhaust gas generated from the boiler 154.

[0134] The fifth embodiment can be applied to the case where the main engine 111 and the auxiliary engine 121 use liquid fuel, but is not limited thereto. Examples of the liquid fuel include, but are not limited to, diesel fuel (e.g., heavy fuel oil (HFO), very low sulfur fuel oil for marine use (VLSFO), marine gas oil (MGO)), methanol, etc. In the fifth embodiment, low-temperature steam can be generated by utilizing exhaust waste heat of the auxiliary engine 121, and used for absorbent regeneration. In the fifth embodiment, at least part of the exhaust gas of the main engine 111 and at least part of the exhaust gas of the auxiliary engine 121 and the boiler 154 can be supplied to the carbon dioxide capture device 140.

[0135] <Sixth Embodiment>

[0136] Figure 10A carbon dioxide capture system for a ship according to the sixth embodiment of the present application is described. The carbon dioxide capture system for a ship includes a carbon dioxide capture device 140 that removes carbon dioxide contained in exhaust gas of a main engine 111, a low-temperature steam generator 150 that generates steam by heat exchange with exhaust gas of an auxiliary engine 121, a low-temperature steam supply line 155 that supplies steam generated from the low-temperature steam supply line 155 to the carbon dioxide capture device 140, a main economizer 112 that is provided on a main engine exhaust line ML connecting the main engine 111 and the carbon dioxide capture device 140, and that generates main steam by heat exchange with exhaust gas of the main engine 111, and a branch line BL that branches from the main engine exhaust line ML at a rear end of the main economizer 112, and that is connected to an exhaust line SL connecting the auxiliary engine 121 and the low-temperature steam generator 150, wherein at least a portion of the main engine exhaust gas that passes through the main economizer 112 can be supplied to the low-temperature steam generator 150 through the branch line BL.

[0137] After high-temperature steam is generated from the main economizer 112, the exhaust gas that is discharged through the exhaust gas discharge line 114 is still high in temperature, and thus needs to be cooled in the pre-cooler 115 to an absorption temperature required by the carbon dioxide capture device 140, and then supplied to the carbon dioxide capture device 140. The higher the temperature of the exhaust gas that is supplied to the pre-cooler 115, the more heat is wasted, and the more the amount of seawater that is required is increased, which also causes energy loss.

[0138] The carbon dioxide capture system according to the sixth embodiment includes the branch line BL that supplies at least a portion of the exhaust gas that passes through the main economizer 112 to the low-temperature steam generator 150, so as to further reduce the temperature of the exhaust gas that is supplied to the pre-cooler 115. That is, the exhaust gas waste heat that is discharged from the main economizer 112 can be reused in the low-temperature steam generator 150, thereby increasing the amount of low-temperature steam that is generated in the low-temperature steam generator 150 and reducing the temperature of the exhaust gas that is supplied to the carbon dioxide capture device 140.

[0139] According to the amount of steam that is generated from the low-temperature steam generator 150, the exhaust gas that is discharged from the main economizer 112 can be selectively supplied to the low-temperature steam generator 150 or directly supplied to the pre-cooler 115.

[0140] Further, at least a portion of the boiler exhaust gas that is generated from the boiler 154 can be joined with the auxiliary engine exhaust line SL and supplied to the low-temperature steam generator 150. Thus, the exhaust gas waste heat that is generated from the boiler 154 can also be used to generate low-temperature steam in the low-temperature steam generator 150.

[0141] Further, as in the fifth embodiment, at least part of the integrated exhaust gas of the low-temperature steam generator 150 can be joined with the main engine exhaust line ML at the rear end of the main economizer 112. Here, the integrated exhaust gas can be a mixture of the main engine exhaust gas of the main engine 111, the auxiliary engine exhaust gas of the auxiliary engine 121, and the boiler exhaust gas of the boiler 154. At least part of the integrated exhaust gas can be supplied to the carbon dioxide capture device 140 to meet the required carbon dioxide emission standard.

[0142] The sixth embodiment can be applied to the case where the main engine 111 and the auxiliary engine 121 use liquid fuel, but is not limited thereto. Examples of the liquid fuel include, but are not limited to, diesel fuel (e.g., heavy fuel oil (HFO), very low sulfur fuel oil for marine use (VLSFO), marine gas oil (MGO)), methanol, etc. The sixth embodiment can generate low-temperature steam by utilizing the exhaust gas waste heat of the main engine 111 and the boiler 154, in addition to the exhaust gas waste heat of the auxiliary engine 121, and can be used for absorbent regeneration. In the sixth embodiment, at least part of the main engine 111 exhaust gas and at least part of the auxiliary engine 121 and the boiler 154 exhaust gas can be supplied to the carbon dioxide capture device 140.

[0143] The first to fourth embodiments differ in that they are embodiments when dual fuel is used, whereas the fifth and sixth embodiments are embodiments when liquid fuel is used (examples of the liquid fuel include, but are not limited to, diesel fuel (e.g., heavy fuel oil (HFO), very low sulfur fuel oil for marine use (VLSFO), marine gas oil (MGO), and methanol, etc.), but they have in common that the exhaust gas of the auxiliary engine 121 is used as a basic heat source for generating low-temperature steam, and the carbon dioxide capture device 140 is disposed on the exhaust gas line of the main engine 111. The configuration of each embodiment is not applied individually, and can be a configuration combined with each other.

[0144] Figure 11 is one of the best embodiments of the present invention and is based on the third embodiment Figure 7 A selective catalytic reduction device (SCR) 190 can be added between the main engine 111 and the main economizer 112, and an SCR 190 or a preheater 200 can be added between the auxiliary engine 121 and the methane oxidation catalyst reactor 180. Further, the SCR 190 can be installed at the rear end of the methane oxidation catalyst reactor 180 or can be installed in parallel. Further, a damper 210 can be provided at a branch point at which the exhaust gas of the main engine 111 is branched to the carbon dioxide capture device 140. The present embodiment can be applied to the case where the main engine 111 and the auxiliary engine 121 use dual fuel (gasoline / diesel), but is not limited thereto.

[0145] Figure 12is another preferred embodiment of the present application and is based on the fifth embodiment Figure 9 An SCR 190 can be added between the main engine 111 and the main economizer 112, and an SCR 190 can be added between the auxiliary engine 121 and the low-temperature steam generator 150. In addition, a damper 210 can be provided at a branch point at which the exhaust gas of the main engine 111 is branched to the carbon dioxide capture device 140. The present embodiment can be applied to a case where the main engine 111 and the auxiliary engine 121 use liquid fuel, but is not limited thereto.

[0146] The above description is merely an example of the technical idea of the present application, and various modifications and changes can be made by those skilled in the art without departing from the essential characteristics of the present application. Therefore, the disclosed embodiments of the present application do not limit the technical idea of the present application, but describe the technical idea of the present application. The scope of the present application is not limited to these exemplary embodiments. The scope of the present application should be interpreted by the following claims, and all technical ideas within the equivalent scope thereof should be interpreted as being included in the scope of the present application.

Claims

1. A carbon dioxide capture system for a marine vessel, comprising: a carbon dioxide capture device that removes carbon dioxide contained in exhaust gas of a main engine; a low temperature steam generator that exchanges heat with exhaust gas of an auxiliary engine to generate steam; and a low temperature steam supply line that supplies the steam generated from the low temperature steam generator to the carbon dioxide capture device.

2. The carbon dioxide capture system according to claim 1, further comprising: a methane oxidation catalyst reactor that is disposed between the auxiliary engine and the low temperature steam generator to remove methane contained in exhaust gas of the auxiliary engine, wherein the low temperature steam generator exchanges heat with the exhaust gas that passes through the methane oxidation catalyst reactor to generate the steam.

3. The carbon dioxide capture system according to claim 1, wherein the low temperature steam supply line is provided with a steam trap for separating liquid water in the steam.

4. The carbon dioxide capture system according to claim 1, wherein the low temperature steam generator is a secondary economizer, and the steam is a low temperature steam having a temperature condition of 100°C or higher and lower than 165°C under a pressure condition of lower than 6 bar gauge.

5. The carbon dioxide capture system according to claim 1, comprising: a first steam valve that is disposed on the low temperature steam supply line and controls an amount of the steam supplied to the carbon dioxide capture device.

6. The carbon dioxide capture system according to claim 1, comprising: a main economizer that exchanges heat with exhaust gas of the main engine to generate main steam; a boiler that receives the main steam preheated via the main economizer to generate high temperature boiler steam; and a second steam valve that is disposed on an additional supply line that supplies the high temperature boiler steam generated from the boiler to the carbon dioxide capture device to convert the high temperature boiler steam to the low temperature steam.

7. The carbon dioxide capture system according to claim 1, further comprising: a main economizer that is disposed on a main engine exhaust line connecting the main engine and the carbon dioxide capture device, and exchanges heat with exhaust gas of the main engine to generate the main steam; a second low temperature steam generator that is disposed on the main engine exhaust line at a rear end of the main economizer, and exchanges heat with the exhaust gas of the main engine that passes through the main economizer to generate second steam; and a second low temperature steam supply line that supplies the second steam generated from the second low temperature steam generator to the carbon dioxide capture device.

8. The carbon dioxide capture system according to any one of the preceding claims, wherein the main engine or the auxiliary engine uses dual fuel.

9. A carbon dioxide capture system for a marine vessel, comprising: a carbon dioxide capture device that removes carbon dioxide contained in exhaust gas of a main engine; a main economizer that exchanges heat with exhaust gas of the main engine to generate main steam; a compound low temperature steam generator that receives exhaust gas of the main engine that passes through the main economizer and exhaust gas of an auxiliary engine together to generate steam; and a low temperature steam supply line that supplies the steam generated from the compound low temperature steam generator to the carbon dioxide capture device.

10. The carbon dioxide capture system according to claim 9, further comprising: ​ ​ ​ ​ a boiler that receives main steam preheated by a main economizer to generate high-temperature boiler steam, At least part of the boiler exhaust gas generated from the boiler is supplied to the composite low-temperature steam generator.

11. A carbon dioxide capture system for a ship, comprising: a carbon dioxide capture device that removes carbon dioxide contained in the exhaust gas of the main engines; a low-temperature steam generator that exchanges heat with exhaust gas from the auxiliary engine to generate steam; and a low-temperature steam supply line that supplies steam generated from the low-temperature steam generator to the carbon dioxide capture device, At least part of the exhaust gas of the auxiliary engine passing through the low-temperature steam generator is connected to the main engine exhaust line connecting the main engine and the carbon dioxide capture device.

12. The carbon dioxide capture system according to claim 11, further comprising: The main economizer is installed on the main engine exhaust line and exchanges heat with the exhaust gas of the main engine to generate main steam. At least part of the exhaust gas of the auxiliary engine that has passed through the low-temperature steam generator is joined to the main engine exhaust line at the rear end of the main economizer.

13. The carbon dioxide capture system according to claim 12, further comprising: a boiler that receives main steam preheated by a main economizer to generate high-temperature boiler steam, At least part of the boiler exhaust gas generated from the boiler is joined to the main engine exhaust line at the rear end of the main economizer.

14. The carbon dioxide capture system according to claim 11, comprising: a main economizer, which is provided on the exhaust line of the main engine and exchanges heat with the exhaust gas of the main engine to generate main steam; and A branch line, which branches off from the main engine exhaust line at the rear end of the main economizer and is connected to the auxiliary engine exhaust line connecting the auxiliary engine and the low-temperature steam generator, At least part of the exhaust gas of the main engine which has passed through the main economizer is supplied to the low-temperature steam generator through a branch line.

15. A carbon dioxide capture system according to any preceding claim, wherein the main engine or the auxiliary engine uses liquid fuel.

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