Carbon dioxide capture system using cool thermal energy

Abstract

The present invention can efficiently separate and capture a large amount of carbon dioxide by liquefying or sublimating (solidifying) it using cold heat through a relatively simple process.

Description

Technology Field

[0001] The present invention relates to a carbon dioxide capture system using cold energy, and more specifically, to a carbon dioxide capture system using cold energy capable of efficiently capturing a large amount of carbon dioxide by liquefying or solidifying (sublimating) carbon dioxide. Background Technology

[0002] Currently, many industrial machines use fossil fuels such as coal, oil, and liquefied natural gas (LNG) as energy sources, and large amounts of carbon dioxide are emitted during the process of converting fossil fuel energy into other forms of energy. As such, the problem of global warming arises from greenhouse gases generated by the excessive use of fossil fuels resulting from industrialization.

[0003] According to scenarios developed by the Intergovernmental Panel on Climate Change (IPCC), temperature increases were estimated as follows, based on the assumptions of no reduction or a gradual reduction in the rate of increase of greenhouse gas emissions. If greenhouse gas emissions are not reduced, temperatures are projected to rise by 1.5 to 4.5°C by the mid-21st century. It will rise to, and 0.2~0.5 every 10 years It was estimated that the temperature would rise at a rate of . If greenhouse gas emissions are gradually reduced, 0.1 to 0.2 every 10 years It is estimated that it will represent a rate of temperature increase. As carbon dioxide is identified as a factor in various environmental changes, such as climate change, many studies are being conducted to reduce carbon dioxide emissions or to capture, store, and utilize it as a useful resource. The use of fossil fuels has long acted as the most significant factor in causing carbon dioxide, which had been stored inside the Earth in the form of coal, oil, and natural gas, to be released back into the atmosphere.

[0004] Apart from reducing carbon dioxide emissions through the application of various policies, the development of technologies, and the diversification of energy sources, the development of technologies to capture carbon dioxide inevitably generated in each process and to utilize or store it through appropriate methods also plays an important role in reducing carbon dioxide emissions.

[0005] In particular, the storage of carbon dioxide requires a carbon sequestration technology process to transport it to a storage location, such as a seabed. For this transportation, not only are storage devices capable of storing large quantities of carbon dioxide and storage vessels equipped with such devices required, but large-scale onshore storage facilities capable of storing carbon dioxide are also necessary before the transportation stage.

[0006] Carbon dioxide storage devices typically store carbon dioxide in a liquid state due to economic considerations; however, this presented a limitation in that a pressure tank was essential to maintain the carbon dioxide at high pressure and low temperature.

[0007] Accordingly, various attempts have been made to separate and capture carbon dioxide in a solid state as dry ice, but the process remains complex, wet and dry capture and detachment methods require a large amount of energy, and it is difficult to process large volumes of gas when using membrane separation methods. In addition, there were limitations in feasibility due to significantly low process efficiency. Prior art literature

[0008] Republic of Korea Registered Patent 10-1546360 The problem to be solved

[0009] The problem that the present invention aims to solve is to provide a carbon dioxide capture system using cold energy that can efficiently capture a large amount of carbon dioxide by liquefying or sublimating (solidifying) it using cold energy. means of solving the problem

[0010] To solve the above-mentioned problem, the present invention provides a carbon dioxide capture system utilizing cold energy, comprising the step of: introducing a gas generated during the combustion of a fossil fuel into a refrigerant circulation unit and bringing it into contact with the surface of a refrigerant circulation section in which the refrigerant circulates in a certain flow direction; and liquefying or solidifying carbon dioxide contained in the gas by the cold energy of the refrigerant and obtaining liquid carbon dioxide or dry ice from the surface of the refrigerant circulation section.

[0011] According to a preferred embodiment of the present invention, the step of obtaining the liquid carbon dioxide or dry ice can separate and capture carbon dioxide by lowering the liquid carbon dioxide or dry ice present on the surface of the refrigerant circulation unit by means of physical force, so that the liquid carbon dioxide or dry ice accumulates on the carbon dioxide capture unit installed at the bottom of the refrigerant circulation unit.

[0012] According to a preferred embodiment of the present invention, the refrigerant circulation unit may be in the form of a pipe in which the refrigerant circulates in a constant flow direction.

[0013] According to a preferred embodiment of the present invention, the refrigerant circulation unit may be in the shape of a rectangular parallelepiped in which the refrigerant circulates in a constant flow direction, and the horizontal length is longer than the vertical height.

[0014] According to a preferred embodiment of the present invention, the refrigerant circulation unit is formed symmetrically around a rotation axis extending in a horizontal direction, and as the rotation axis rotates, liquid carbon dioxide or dry ice present on the surface of the refrigerant circulation unit may descend and accumulate in the carbon dioxide capture unit.

[0015] According to a preferred embodiment of the present invention, the refrigerant circulation unit is connected to a refrigerant generator, and the refrigerant contained in the refrigerant circulation unit is transferred to the refrigerant generator after performing heat exchange with carbon dioxide, and can be circulated by being transferred back to the refrigerant circulation unit after being cooled again through the refrigerant generator.

[0016] According to a preferred embodiment of the present invention, prior to the step of obtaining liquid carbon dioxide or dry ice, the method comprises: a step of condensing and removing moisture contained in the gas generated during the fossil fuel combustion process; a step of adsorbing carbon dioxide contained in the gas from which moisture has been removed using an adsorbent; a step of desorbing the carbon dioxide adsorbed on the adsorbent through a vacuum pump; and a step of primary cooling of the high-concentration carbon dioxide gas using cold energy by passing the gas, whose volume has been reduced through the adsorption and desorption of carbon dioxide, through a heat exchanger to exchange heat with LNG or liquid nitrogen; and the gas whose temperature has been lowered through the primary cooling can be introduced into the refrigerant circulation unit.

[0017] According to a preferred embodiment of the present invention, in the adsorption step, the adsorbent may be a porous support.

[0018] According to a preferred embodiment of the present invention, the adsorption step may result in the carbon dioxide being physically dry-adsorbed onto the adsorbent, and nitrogen and oxygen being discharged, thereby reducing the total volume of the gas from which moisture has been removed and increasing the concentration of carbon dioxide contained in the gas from which moisture has been removed.

[0019] According to a preferred embodiment of the present invention, in the step of adsorbing, the adsorption is performed in an adsorption system comprising at least one porous bed packed with the adsorbent, and may be performed in a vacuum swing absorption (VSA) or pressure swing absorption (PSA) manner. Effects of the invention

[0020] The present invention can efficiently separate and capture a large amount of carbon dioxide by liquefying or sublimating (solidifying) it using cold heat through a relatively simple process. Brief explanation of the drawing

[0021] FIG. 1 is a conceptual diagram of a refrigerant circulation unit according to a preferred embodiment of the present invention. Figure 2 is a phase diagram of carbon dioxide. FIG. 3 is a conceptual diagram of a refrigerant circulation unit according to a preferred embodiment of the present invention. FIG. 4 is a process diagram of a carbon dioxide capture system using cold heat according to a preferred embodiment of the present invention. Specific details for implementing the invention

[0022] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention.

[0023] As mentioned above, existing methods for separating and capturing carbon dioxide into solid dry ice require high-pressure processes or large amounts of cold energy; consequently, this results in significantly low process efficiency and has limitations that reduce feasibility.

[0024] Accordingly, the present invention seeks a solution to the aforementioned limitations by providing a carbon dioxide capture system utilizing cold energy, comprising the step of: a gas generated during the combustion of fossil fuels being introduced into a refrigerant circulation unit and coming into contact with the surface of a refrigerant circulation section in which the refrigerant circulates in a certain flow direction; and carbon dioxide contained in the gas being liquefied or solidified by the cold energy of the refrigerant and obtained as liquefied carbon dioxide or dry ice on the surface of the refrigerant circulation section.

[0025] Accordingly, the present invention can perform liquefaction or solidification of carbon dioxide by utilizing the cold energy of the refrigerant simply by introducing a gas containing carbon dioxide and bringing it into contact with the refrigerant circulation unit, and can efficiently separate and capture a large amount of carbon dioxide with only a simple process by separating and collecting the liquefied carbon dioxide or dry ice formed on the surface of the refrigerant circulation unit.

[0026] In this regard, FIG. 1 is a conceptual diagram of a refrigerant circulation unit (500) according to a preferred embodiment of the present invention. Referring to FIG. 1, the refrigerant circulation unit (500) may be formed with a refrigerant circulation section (510) through which a refrigerant circulates and a carbon dioxide capture section (520) capable of separating and capturing carbon dioxide. In the refrigerant circulation unit (500), the refrigerant circulates in a constant flow direction (S1→S2), and as the gas comes into contact with the surface of the refrigerant circulation section (510), the carbon dioxide contained in the gas is solidified (sublimated) or liquefied by the cold heat of the refrigerant. Accordingly, liquid carbon dioxide or dry ice is formed on the surface of the refrigerant circulation section (510). Subsequently, the carbon dioxide or dry ice is separated and captured using the carbon dioxide capture section (520), thereby efficiently separating and capturing carbon dioxide contained in the gas generated during the fossil fuel combustion process in a solid or liquid state.

[0027] The refrigerant circulation unit (510) circulates the refrigerant in a constant flow direction. The refrigerant circulation unit (510) receives the refrigerant and cools the carbon dioxide by utilizing the cold energy of the refrigerant.

[0028] Various refrigerants commonly available in the relevant technical field may be used, and those capable of obtaining dry ice or liquid carbon dioxide by cooling and solidifying or liquefying carbon dioxide may be used.

[0029] In this regard, FIG. 2 is a phase diagram of carbon dioxide. Referring to FIG. 2, it is necessary to control the temperature range to solidify or liquefy carbon dioxide gas. For example, to obtain dry ice by solidifying carbon dioxide gas, cooling to a temperature range of about -78.5 to -56.4°C is required (P1). In addition, to obtain liquid carbon dioxide by liquefying carbon dioxide gas, cooling to a temperature range of about -56.4 to 31.1°C is required (P2). Therefore, the present invention is preferable to select and use a refrigerant capable of cooling carbon dioxide to the above-described temperature range.

[0030] The shape of the refrigerant circulation section (510) may be such that it can accommodate refrigerant, allow the refrigerant to circulate in a constant flow direction, and have a large external surface area to provide a contact area with gas. Preferably, the refrigerant circulation section (510) may be in the form of a pipe or a rectangular prism with a horizontal length longer than its vertical height.

[0031] In this regard, referring to FIG. 1, the refrigerant circulation unit (510) is formed in the form of a pipe, and may be in the form of a long cylindrical pipe. In this case, the refrigerant is circulated in a constant flow direction (S1→S2) through the refrigerant circulation unit (510), and accordingly, carbon dioxide contained in the gas introduced into the refrigerant circulation unit (500) is liquefied or solidified by cold heat on the surface of the refrigerant circulation unit (510) and can be obtained as liquefied carbon dioxide or dry ice (D).

[0032] Additionally, FIG. 3 is a conceptual diagram of a refrigerant circulation unit (500) according to a preferred embodiment of the present invention. Referring to FIG. 3, the refrigerant circulation unit (510) may be formed in the shape of a rectangular prism where the horizontal length is longer than the vertical height. In this case, the surface area of ​​the refrigerant circulation unit (510) that can come into contact with the gas is formed wide, which has the effect of efficiently cooling a large amount of carbon dioxide. In this case as well, the refrigerant is circulated in a constant flow direction (S1→S2) through the refrigerant circulation unit (510), and accordingly, the carbon dioxide contained in the gas introduced into the refrigerant circulation unit (500) may be liquefied or solidified by cold heat on the surface of the refrigerant circulation unit (510) to obtain liquid carbon dioxide or dry ice (D).

[0033] Meanwhile, the refrigerant circulation unit (510) receives a refrigerant, and can maintain cold heat by repeatedly exchanging heat through the circulation of the refrigerant in a constant flow direction.

[0034] Specifically, the refrigerant circulation unit (500) is connected to the refrigerant generator (600), and the refrigerant contained in the refrigerant circulation unit (500) is transferred to the refrigerant generator (600) after performing heat exchange with carbon dioxide, and can be circulated by being transferred back to the refrigerant circulation unit (500) after being cooled again through the refrigerant generator (600). Through this, the refrigerant contained in the refrigerant circulation unit (510) can maintain cold heat, and carbon dioxide can be efficiently cooled to obtain liquid carbon dioxide or dry ice in a solid or liquid state.

[0035] The carbon dioxide capture unit (520) provides a space for separating and collecting liquefied or solidified liquid carbon dioxide or dry ice.

[0036] In this regard, the step of obtaining the liquid carbon dioxide or dry ice can separate and collect carbon dioxide by lowering the liquid carbon dioxide or dry ice present on the surface of the refrigerant circulation unit (510) by physical force so that the liquid carbon dioxide or dry ice accumulates on the carbon dioxide capture unit (520) installed at the bottom of the refrigerant circulation unit (510).

[0037] That is, a physical force of a certain level or higher is applied to separate the liquid carbon dioxide or dry ice formed by cooling carbon dioxide on the surface of the refrigerant circulation unit (510), and thereby the liquid carbon dioxide or dry ice can be separated from the surface of the refrigerant circulation unit (510) and descend to the carbon dioxide capture unit (520) installed below the refrigerant circulation unit (510). Accordingly, the liquid carbon dioxide or dry ice accumulates on the installed carbon dioxide capture unit (520), and carbon dioxide can be separated and captured by separating and capturing it.

[0038] At this time, physical force refers to the application of an external force exceeding a certain level, for example, by applying an impact exceeding a certain level or by scraping or scraping the surface of the refrigerant circulation unit (510) with a force exceeding a certain level.

[0039] The carbon dioxide capture unit (520) can be formed in various shapes capable of accommodating liquid carbon dioxide or dry ice. It can be formed from materials commonly used in process systems in the relevant field of technology.

[0040] According to a preferred embodiment of the present invention, the refrigerant circulation unit (510) is formed symmetrically around a rotation axis extending in a horizontal direction, and as the rotation axis rotates, liquid carbon dioxide or dry ice present on the surface of the refrigerant circulation unit (510) descends and accumulates in the carbon dioxide collection unit (520) to separate and collect carbon dioxide.

[0041] In this regard, referring to FIGS. 1 and FIGS. 3, it can be seen that the refrigerant circulation unit (510) is formed symmetrically around a virtual rotation axis extending in the horizontal direction and rotates (R) around this central axis. Accordingly, liquid carbon dioxide or dry ice (D) present on the surface of the refrigerant circulation unit (510) descends (F) and accumulates in the carbon dioxide capture unit (520), thereby separating and capturing carbon dioxide.

[0042] Meanwhile, this rotation (R) can be performed simultaneously with or separately from the application of the physical force described above, and preferably simultaneously. That is, liquid carbon dioxide or dry ice can be separated by applying an impact of a certain level or higher to the surface of the refrigerant circulation unit (510) or by scraping or writing the surface of the refrigerant circulation unit (510) with a force of a certain level or higher, while the refrigerant circulation unit (510) rotates so that the liquid carbon dioxide or dry ice can be easily separated and descended to be received in the carbon dioxide capture unit (520).

[0043] According to a preferred embodiment of the present invention, prior to the step of obtaining liquid carbon dioxide or dry ice, the method may include: a step of condensing and removing moisture contained in the gas generated during the fossil fuel combustion process; a step of adsorbing carbon dioxide contained in the gas from which moisture has been removed using an adsorbent; a step of desorbing the carbon dioxide adsorbed on the adsorbent through a vacuum pump; and a step of primary cooling of the high-concentration carbon dioxide gas using cold energy by passing the gas, whose volume has been reduced through the adsorption and desorption of carbon dioxide, through a heat exchanger to exchange heat with LNG or liquid nitrogen. At this time, the gas whose temperature has been lowered through primary cooling may be introduced into a refrigerant circulation unit (500).

[0044] Accordingly, the present invention can improve heat transfer energy efficiency by significantly reducing the volume of the gas being cooled through a pretreatment process using an adsorbent, thereby reducing the amount of heat required for cooling through the high concentration of the incoming gas. In addition, the present invention can separate and capture carbon dioxide by liquefying or sublimating (solidifying) it using cold energy through a relatively simple process without high pressure conditions by performing a multi-stage cooling process using LNG (liquefied natural gas), liquid nitrogen, and a refrigerant circulation unit (500). Through this, the present invention can improve the efficiency of carbon dioxide separation and capture.

[0045] First, FIG. 4 is a process diagram of a carbon dioxide capture system using cold energy according to a preferred embodiment of the present invention. Referring to FIG. 4, the present invention allows gas generated during the combustion of fossil fuels to be discharged from a chimney, pass through an exhaust gas cooling heat exchanger (100), and flow into a condenser (200). Through this, a step (S10) is performed to condense and remove moisture contained in the gas generated during the combustion of fossil fuels. The gas from which moisture has been removed through the condenser (200) is transferred to an adsorption system (300), and a step (S20) is performed to adsorb carbon dioxide from the gas from which moisture has been removed using an adsorbent. At this time, a large amount of nitrogen, oxygen, etc. contained in the exhaust gas is discharged through the upper part of the adsorption system (300). Subsequently, a step (S30) is performed to desorb the carbon dioxide adsorbed on the adsorbent using a vacuum pump (310). At this time, the gas whose volume has been reduced through the adsorption and desorption of carbon dioxide may be transferred to a carbon dioxide storage tank (320) at a rapid speed via a vacuum pump (310) and then transferred to a heat exchanger (400). The desorbed high-concentration carbon dioxide gas is transferred to a heat exchanger (400) where primary cooling is performed, and a step (S40) of primary cooling using cold energy is performed by passing it through the heat exchanger (400) to exchange heat with LNG or liquid nitrogen. The gas whose temperature has been lowered through primary cooling is transferred to a refrigerant circulation unit (500). Through this, a step (S50) is performed in which the carbon dioxide contained in the gas whose temperature has been lowered through primary cooling is liquefied or sublimated (solidified) using the refrigerant circulation unit (500) to separate and collect dry ice in a liquid or solid state. Through the process described above, the present invention can efficiently separate and capture carbon dioxide contained in the gas generated during the combustion of fossil fuels into liquid carbon dioxide or solid dry ice.

[0046] The step (S10) of condensing and removing moisture contained in the gas generated during the fossil fuel combustion process removes the moisture contained in the gas by cooling the gas. This can be performed using a condenser (200) or by using the cold energy of the low-temperature gas discharged from the refrigerant circulation unit (500).

[0047] Typically, most adsorbents are hydrophilic, so moisture tends to be adsorbed onto them. Consequently, moisture is preferentially adsorbed onto the adsorbent or is competitively adsorbed and does not easily desorb, which reduces the specific surface area of ​​the porous support and can significantly lower the adsorption efficiency of carbon dioxide.

[0048] Accordingly, the present invention has the effect of improving the adsorption efficiency of carbon dioxide using an adsorbent by preferentially condensing and removing moisture contained in the gas prior to the adsorption process.

[0049] In addition, if the gas temperature is high, difficulties may arise where the gas is not firmly adsorbed to the adsorbent, or even if adsorbed, it may easily detach. Accordingly, the present invention has the effect of improving process efficiency by lowering the gas temperature through cooling the gas prior to the adsorption process, thereby increasing the adsorption rate to the adsorbent.

[0050] The step (S20) of adsorbing carbon dioxide contained in the moisture-removed gas using an adsorbent adsorbs carbon dioxide (CO2) contained in the moisture-removed gas.

[0051] At this time, a significant amount of excess gas, such as nitrogen (N2) and oxygen (O2), can be discharged through the upper part of the adsorption system (300).

[0052] Specifically, the gas from which moisture has been removed contains more excess gases such as nitrogen and oxygen in addition to carbon dioxide. Referring to Fig. 4, the gas typically inlet to a carbon dioxide capture system may consist of 80 to 90 volume% nitrogen, 0 to 5 volume% oxygen, and 5 to 20 volume% carbon dioxide. As such, it is common for the gas generated during the combustion of fossil fuels to contain 10 to 20 volume% carbon dioxide.

[0053] For this reason, when attempting to obtain solid dry ice by sublimating (solidifying) carbon dioxide by cooling the entire gas containing nitrogen or oxygen using cold energy, a significantly large amount of energy is required, and consequently, the heat transfer energy efficiency becomes significantly lower, which leads to a limitation in that the process becomes complex and process efficiency decreases.

[0054] Accordingly, the present invention first performs a pretreatment process in which, prior to cooling using cold heat, carbon dioxide contained in the gas from which moisture has been removed is adsorbed by an adsorbent, and excess gases such as nitrogen or oxygen are discharged through the upper part of the adsorption system (300). Through this, most of the excess gases such as nitrogen or oxygen can be discharged. Specifically, the present invention causes an excess amount of carbon dioxide to adhere to the surface and internal pores of the adsorbent, and then, when the adhesion performance of the adsorbent deteriorates at a specific point in time, the inflow of gas is blocked, and carbon dioxide is desorbed through a vacuum pump (310) as described below, thereby performing high concentration of carbon dioxide.

[0055] The carbon dioxide volume concentration of the gas whose volume is reduced by passing through the adsorption system (300) can be 50 volume% or more, and preferably 60 volume% or more.

[0056] Thus, the present invention can improve heat transfer energy efficiency by significantly reducing the volume of the gas to be cooled using cold energy and increasing the carbon dioxide concentration of the incoming gas, thereby reducing the amount of heat required for cooling. In other words, by increasing the concentration of carbon dioxide, the energy loss required for cooling unnecessary gases such as nitrogen and oxygen can be minimized, and thereby the cooling effect using cold energy can be significantly enhanced.

[0057] As a specific example, assuming that the volume composition ratio of the incoming gas entering the adsorption system (300) is 90 volume% nitrogen and 10 volume% carbon dioxide, if the carbon dioxide is cooled to -80°C, which is the temperature range for sublimation under atmospheric pressure conditions, the amount of heat required to cool the nitrogen is 160 kcal / min. On the other hand, as described above, if the carbon dioxide volume concentration is increased to 60 volume% through the adsorption system (300), the amount of heat required to cool 40 volume% nitrogen within the same temperature range would be only 12 kcal / min. Therefore, the present invention can reduce the amount of cooling required to cool the gas containing carbon dioxide to about 1 / 13, and accordingly, the heat transfer energy efficiency can be significantly improved.

[0058] According to a preferred embodiment of the present invention, the adsorption step (S20) can be performed by physically dry adsorbing carbon dioxide onto an adsorbent.

[0059] Through this, carbon dioxide among the gases from which moisture has been removed is adsorbed onto the adsorbent, and most excess gases such as nitrogen and oxygen are discharged, thereby reducing the total volume and increasing the concentration of carbon dioxide to be separated and captured, which reduces the amount of heat required for cooling through the high concentration of carbon dioxide, thereby improving the heat transfer energy efficiency.

[0060] In this case, a porous support can be used as the adsorbent. Preferably, zeolite, activated carbon, silica, metal-organic frameworks, etc., can be used. In this case, carbon dioxide can be purified by penetrating and adsorbing within the porous space with a large surface area.

[0061] Meanwhile, the adsorption step (S20) may be performed in an adsorption system (300) comprising at least one porous bed packed with an adsorbent. That is, the adsorption described above may be performed through an adsorption system (300) comprising one or more beds (packing beds) filled with a porous support that is an adsorbent. Preferably, a plurality of porous beds packed with an adsorbent may be included within a single adsorption system (300) to form a multilayer structure. At this time, the number of porous beds packed with an adsorbent may be increased or decreased considering the amount of flue gas, pressure loss, carbon dioxide capture efficiency, etc. That is, a fixed-bed adsorption reaction device having a multilayer packed structure may be used as the adsorption system (300).

[0062] Forming a multilayer structure in this way has the advantage of improving the amount and efficiency of carbon dioxide captured.

[0063] In addition, the above adsorption can be performed using a vacuum swing absorption (VSA) or pressure swing absorption (PSA) method.

[0064] According to a preferred embodiment of the present invention, the adsorption step (S20) can be performed through multiple continuous processes by connecting two or more adsorption systems (300) in parallel. More preferably, 2 to 5 adsorption systems (300) can be connected in parallel.

[0065] In addition, the above multiple continuous processes are preferably performed within minutes, and more preferably within 1 to 3 minutes assuming that 6 to 10 tons of carbon dioxide are processed per day.

[0066] As described above, the present invention can perform carbon dioxide adsorption through physical dry adsorption based on van der Waals forces; however, in this case, the adsorption performance may deteriorate over time. Accordingly, by performing multiple continuous processes within a short period, it is possible to more easily achieve a high concentration of carbon dioxide.

[0067] The step (S30) of desorbing carbon dioxide adsorbed on the adsorbent through the vacuum pump (310) separates the carbon dioxide by desorbing it due to the pressure difference by passing the gas with adsorbed carbon dioxide through the vacuum pump (310) as described above.

[0068] In this way, the volume of the gas can be reduced through the adsorption and desorption of carbon dioxide, and the concentration of carbon dioxide can be increased.

[0069] The gas, with its volume reduced through the adsorption and desorption of carbon dioxide, can be transferred to a carbon dioxide storage tank (320) at a high speed via a vacuum pump (310) and then transferred to a heat exchanger (400) as described below.

[0070] The step (S40) of primary cooling using cold heat by passing the gas with reduced volume through the adsorption and desorption of carbon dioxide through a heat exchanger (400) to exchange heat with LNG or liquid nitrogen can lower the temperature of the gas with reduced volume through the adsorption and desorption of carbon dioxide to a predetermined temperature range.

[0071] Referring to FIG. 4, the gas with reduced volume through the adsorption system (300) is transferred to a heat exchanger (400) and its temperature is lowered through primary cooling using the cold energy of the LNG. As described above, it may also be transferred to the heat exchanger (400) after being transferred at a rapid speed to the carbon dioxide storage tank (320) through the vacuum pump (310).

[0072] In the heat exchanger (400), the temperature of the gas can be lowered from a high temperature to a low temperature within a predetermined range through cold energy utilizing the phase change energy required for the LNG to vaporize. Specifically, in order to use LNG, it must be vaporized from a liquid state of -162°C into a gas within a range of 0°C or higher, and the gas of the present invention is first cooled using cold energy utilizing the phase change energy required at this time. After performing the first cooling, the temperature of the gas may be -50 to -30°C. Since carbon dioxide still exists as a gas under the above temperature range and atmospheric pressure conditions, an additional cooling process is required to obtain dry ice in a solid state, as described below.

[0073] According to a preferred embodiment of the present invention, in the first cooling step (S30), the LNG used for heat exchange is discharged as NG (natural gas) from the heat exchanger (400), and the NG is transferred to the flue gas cooling heat exchanger (100) to lower the temperature of the flue gas cooling heat exchanger (100), thereby lowering the temperature of the gas generated during the fossil fuel combustion process.

[0074] Specifically, referring to FIG. 4, LNG is introduced (X) into a heat exchanger (400), and the gas containing carbon dioxide is cooled first using the cold energy of the LNG. The LNG used for heat exchange can be vaporized into NG and transferred (Y) from the heat exchanger (400) to the flue gas cooling heat exchanger (100). Through this, the flue gas cooling heat exchanger (100) can be cooled first using NG containing a significant amount of cold energy, thereby lowering the temperature of the flue gas to a predetermined range. In this case, the process efficiency can be further improved by lowering the temperature of the high-temperature gas discharged from the flue gas cooling heat exchanger (100) to a predetermined range before performing the process (S10, S20, S30, S40, etc.) of the present invention. Afterwards, the NG can be transferred (Z2) to various places such as an LNG thermal power plant, an LNG reforming hydrogen refueling station, an LNG vessel, various other factories using LNG as fuel, district heating facilities, and waste incineration plants, and can be utilized effectively.

[0075] Ultimately, the present invention can efficiently capture a large amount of carbon dioxide by liquefying or sublimating (solidifying) it using cold energy. Furthermore, through a multi-stage cooling process, carbon dioxide can be separated and captured by sublimating (solidifying) it using cold energy with a relatively simple process, even without high-pressure conditions. In addition, energy saving is possible by effectively recycling or circulating the refrigerant.

Claims

Claim 1 The method comprises: a step of condensing and removing moisture contained in the gas generated during the combustion of fossil fuels; a step of adsorbing carbon dioxide contained in the gas from which moisture has been removed using an adsorbent; a step of desorbing the carbon dioxide adsorbed on the adsorbent through a vacuum pump; and a step of primary cooling of high-concentration carbon dioxide gas using cold energy by passing the gas, whose volume has been reduced through the adsorption and desorption of carbon dioxide, through a heat exchanger to exchange heat with LNG or liquid nitrogen; and a step in which the gas whose temperature has been lowered through the primary cooling is introduced into a refrigerant circulation unit and comes into contact with the surface of a refrigerant circulation section, which is in the form of a cylindrical pipe in which the refrigerant circulates in a constant flow direction, and the carbon dioxide contained in the gas is liquefied or solidified by the cold energy of the refrigerant to obtain liquid carbon dioxide or dry ice on the surface of the refrigerant circulation section; wherein the refrigerant circulation section is formed such that its horizontal length is longer than its vertical height and is formed symmetrically around a rotation axis extending in the horizontal direction, and as the rotation axis rotates, the liquid carbon dioxide or dry ice present on the surface of the refrigerant circulation section is lowered by physical force, A carbon dioxide capture system utilizing cold energy, wherein carbon dioxide is separated and captured by causing liquid carbon dioxide or dry ice to accumulate on a carbon dioxide capture unit installed below the refrigerant circulation unit, the refrigerant circulation unit is connected to a refrigerant generator, and the refrigerant contained in the refrigerant circulation unit is transferred to the refrigerant generator after performing heat exchange with carbon dioxide, and circulates by being transferred back to the refrigerant circulation unit after being cooled again through the refrigerant generator. Claim 2 A carbon dioxide capture system using cold energy according to claim 1, wherein the physical force is performed by applying an impact of a certain level or higher to the refrigerant circulation part or by scraping the surface of the refrigerant circulation part with a force of a certain level or higher. Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 In claim 1, in the adsorption step, the adsorbent is a porous support, a carbon dioxide capture system using cold heat. Claim 9 A carbon dioxide capture system using cold heat according to claim 1, wherein the adsorption step is such that the carbon dioxide is physically dry-adsorbed onto the adsorbent, and nitrogen and oxygen are discharged, thereby reducing the total volume of the gas from which moisture has been removed and increasing the concentration of carbon dioxide contained in the gas from which moisture has been removed. Claim 10 A carbon dioxide capture system using cold energy according to claim 1, wherein in the adsorption step, the adsorption is performed in an adsorption system comprising at least one porous bed packed with the adsorbent, and is performed by a vacuum swing absorption (VSA) or pressure swing absorption (PSA) method.

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