A carbon capture system

Abstract

The application provides a carbon capture system, a drying tower, a main heat exchanger, a spray tower device and a carbon capture liquid supply device; flue gas dewatered through the drying tower enters the main heat exchanger, the main heat exchanger performs precooling treatment on the flue gas, the precooling treated flue gas enters the spray tower device, is cooled by carbon capture liquid input into the spray tower device by the carbon capture liquid supply device in the spray tower device, carbon dioxide in the flue gas is cooled to the condensation temperature of the carbon dioxide to obtain dry ice, the dry ice is liquefied to obtain liquid carbon dioxide, and the liquid carbon dioxide passes through the main heat exchanger to obtain high-concentration liquid carbon dioxide. Through the carbon capture system provided in the application, the evaporation amount of the carbon capture liquid by the flue gas can be reduced.

Description

Technical Field

[0001] This application relates to the field of carbon capture technology, and more specifically, to a carbon capture system. Background Technology

[0002] Currently, the sublimation method in cryogenic carbon capture is attracting increasing attention. The sublimation method involves feeding flue gas from a power plant into a cryogenic (below 195K (-78.15℃)) carbon capture device. The carbon capture liquid in the box-type cryogenic carbon capture device sublimates the carbon dioxide in the flue gas, and the resulting dry ice is then captured and recovered. However, if the flue gas temperature is high, the carbon capture liquid may evaporate during the sublimation process, reducing its capture efficiency. Summary of the Invention

[0003] To address the aforementioned problems, the purpose of this application is to provide a carbon capture system.

[0004] In a first aspect, embodiments of this application provide a carbon capture system, including: a drying tower, a main heat exchanger, a spray tower device, and a carbon capture liquid supply device;

[0005] The drying tower, the main heat exchanger, the spray tower equipment, and the carbon capture liquid supply equipment are connected in sequence;

[0006] The flue gas dehydrated by the drying tower enters the main heat exchanger, which pre-cools the flue gas. The pre-cooled flue gas then enters the spray tower, where it is cooled by the carbon capture liquid supplied by the carbon capture liquid supply device. This cools the carbon dioxide in the flue gas to its sublimation temperature, resulting in dry ice. The dry ice is then liquefied to obtain liquid carbon dioxide. After passing through the main heat exchanger, the liquid carbon dioxide is obtained as a high-concentration liquid carbon dioxide.

[0007] In the solution provided by the first aspect of this application embodiment, the main heat exchanger in the carbon capture system is used to pre-cool the flue gas after it has been dehydrated in the drying tower. Compared with the related technology where the carbon capture liquid is used to condense high-temperature flue gas, which leads to a large amount of evaporation of the carbon capture liquid, the main heat exchanger is used to pre-cool the flue gas before it enters the spray tower equipment to reduce the temperature of the flue gas entering the spray tower equipment. As the temperature of the flue gas entering the spray tower equipment decreases, the temperature difference between the flue gas and the carbon capture liquid is reduced, which can reduce the amount of evaporation of the carbon capture liquid by the flue gas. Moreover, the spray tower equipment is used to collect the dry ice after the carbon dioxide in the flue gas has condensed, which avoids the defects of dry ice condensation on the inner wall of the box-type low-temperature carbon capture equipment, such as difficulty in dry ice collection, equipment corrosion, and poor thermal conductivity.

[0008] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 A schematic diagram of the structure of a carbon capture system provided in Embodiment 1 of this application is shown. Detailed Implementation

[0011] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0012] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0013] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0014] Carbon dioxide capture is a key research area in carbon emission reduction technologies. Improving capture efficiency and reducing equipment energy consumption are crucial for the future of industrial applications and the achievement of national carbon emission targets. As a major carbon emitter and coal producer, my country's main carbon emissions come from coal-fired power plants, characterized by large emissions, concentrated emissions, and relatively low carbon dioxide concentrations. There are three main types of carbon capture technologies: pre-combustion capture, oxy-fuel combustion capture, and post-combustion capture. Post-combustion capture is more adaptable, requiring no modifications to existing power plant systems, and is therefore better suited to my country's national conditions. Post-combustion capture technologies can be further subdivided into: absorption, adsorption, membrane separation, microalgae treatment, and cryogenic methods.

[0015] In recent years, the sublimation method in cryogenic processes has received increasing attention. The sublimation method involves feeding flue gas from a power plant into a cryogenic (below 195K (-78.15℃)) carbon capture device. The carbon capture liquid in the box-type cryogenic carbon capture device sublimates the carbon dioxide in the flue gas, producing solid dry ice, which is then captured and recovered. This method features high capture efficiency, high concentration of captured carbon dioxide, and is environmentally friendly with no secondary pollutants. However, if the flue gas temperature is high, the carbon capture liquid may evaporate during the sublimation process, reducing its capture efficiency.

[0016] Based on this, the following embodiments of this application propose a carbon capture system. The main heat exchanger in the carbon capture system pre-cools the flue gas after it has been dehydrated in the drying tower, thereby reducing the temperature of the flue gas entering the spray tower. As the flue gas temperature decreases, the carbon capture liquid cools the flue gas to the carbon dioxide sublimation temperature. This reduces the temperature difference between the flue gas and the carbon capture liquid, decreasing the evaporation rate of the carbon capture liquid and thus improving the carbon capture efficiency of the carbon capture liquid for carbon dioxide in the flue gas. Furthermore, the spray tower collects the dry ice formed by the sublimation of carbon dioxide in the flue gas, minimizing the drawbacks of dry ice condensation on the inner wall of the box-type low-temperature carbon capture equipment, which can lead to difficulties in dry ice collection, equipment corrosion, and poor thermal conductivity.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0018] Example

[0019] See Figure 1 The schematic diagram of the carbon capture system shown in this embodiment is a carbon capture system including: a drying tower 1, a main heat exchanger 2, a spray tower device and a carbon capture liquid supply device.

[0020] The drying tower 1, the main heat exchanger 2, the spray tower equipment, and the carbon capture liquid supply equipment are connected in sequence.

[0021] The flue gas dehydrated by the drying tower 1 enters the main heat exchanger 2, where it is pre-cooled. The pre-cooled flue gas then enters the spray tower, where it is cooled by the carbon capture liquid supplied by the carbon capture liquid supply device. This cools the carbon dioxide in the flue gas to its sublimation temperature, resulting in dry ice. The dry ice is then liquefied to obtain liquid carbon dioxide, which is then passed through the main heat exchanger 2 to obtain a high-concentration liquid carbon dioxide.

[0022] In one implementation, high-concentration liquid carbon dioxide can refer to liquid carbon dioxide with a low concentration of 80% or higher.

[0023] Drying tower 1 is used to remove water and dry the flue gas that has undergone dust removal, desulfurization and denitrification in order to prevent ice blockage in the pipeline.

[0024] The main heat exchanger 2 is used to pre-cool the dried flue gas, reduce the flue gas temperature, reduce the evaporation of the carbon capture liquid in the next step, and recover the cooling capacity of the decarbonized flue gas and liquid carbon dioxide.

[0025] To better condense carbon dioxide in flue gas, the carbon capture liquid can be, but is not limited to, isopentane liquid or a mixture of isopentane and n-pentane. Preferably, to achieve a lower temperature and higher carbon capture rate, more isopentane liquid is added to the carbon capture liquid.

[0026] For example, when the carbon capture solution is a cryogenic isopentane liquid, the temperature of the cryogenic isopentane liquid can be, but is not limited to: 168.15 K (-105 °C) for a cryogenic isopentane liquid with a carbon capture rate of 80%, 153.15 K (-120 °C) for a cryogenic isopentane liquid with a carbon capture rate of 90%, and 138.15 K (-135 °C) for a cryogenic isopentane liquid with a carbon capture rate of 99%.

[0027] To further improve the carbon dioxide capture efficiency in flue gas, the carbon capture system proposed in this embodiment includes a spray tower device comprising a first spray tower 3 and a second spray tower 4; correspondingly, the carbon capture liquid comprises a first liquid capture medium input into the first spray tower 3 and a second liquid capture medium input into the second spray tower 4; the dry ice comprises a first portion of dry ice obtained from the first spray tower 3 and a second portion of dry ice obtained from the second spray tower 4.

[0028] As can be seen from the above description, the first liquid trapping medium and the second liquid trapping medium can be, but are not limited to, isopentane liquid or isopentane-n-pentane mixed liquid.

[0029] Optionally, the first spray tower 3 and the second spray tower 4 can be respectively adopted as low-temperature spray towers.

[0030] In one embodiment, the first spray tower 3 and the second spray tower 4 are respectively provided with a solid-liquid collection tank, a lower air inlet, an upper carbon capture liquid inlet, a nozzle, and a top air outlet; wherein, the solid-liquid collection tank is respectively located at the bottom of the first spray tower 3 and the second spray tower 4, the lower air inlet can be respectively located at the lower part of the first spray tower 3 and the second spray tower 4 and the air intake method of the lower air inlet is from bottom to top, the upper carbon capture liquid inlet can be respectively located at the upper part of the first spray tower 3 and the second spray tower 4, the upper carbon capture liquid inlet is connected to the nozzle through a hose, and the top air outlet is respectively located at the top of the first spray tower 3 and the second spray tower 4.

[0031] The top air outlet of the first spray tower 3 is connected to the lower air inlet of the second spray tower 4; the top air outlet of the second spray tower 4 is connected to the main heat exchanger 2.

[0032] The first spray tower 3 is connected to the main heat exchanger 2 and the second spray tower 4 respectively, and the first spray tower 3 and the second spray tower 4 are connected to the carbon capture liquid supply equipment respectively.

[0033] The first spray tower 3 is used to cool the carbon dioxide gas in the flue gas to below the condensation point by spraying a first liquid collection medium with a first temperature under atmospheric pressure, and to separate most of the carbon dioxide in the flue gas in the form of dry ice, thereby obtaining and collecting the first part of dry ice.

[0034] The second spray tower 4 is used to cool the carbon dioxide gas in the flue gas to below the condensation point by spraying a second liquid collection medium with a second temperature at atmospheric pressure. If necessary, a second liquid collection medium with a lower temperature than the first liquid collection medium sprayed by the first spray tower 3 can be used to condense the carbon dioxide in the cold flue gas. The remaining carbon dioxide in the cold flue gas after carbon capture by the first spray tower 3 is then subjected to secondary condensation, and the second part of dry ice obtained after secondary condensation is collected.

[0035] The pre-cooled flue gas enters the first spray tower 3. Inside the first spray tower 3, the first liquid collection medium with a first temperature, which is supplied by the carbon capture liquid supply device, cools the flue gas to the sublimation temperature of carbon dioxide, resulting in the first portion of dry ice and cold flue gas. The first portion of dry ice is liquefied to obtain liquid carbon dioxide from the first portion of dry ice. The liquid carbon dioxide from the first portion of dry ice passes through the main heat exchanger to obtain high-concentration liquid carbon dioxide. The cold flue gas is then fed into the second spray tower.

[0036] The first liquid collection medium, fed into the first spray tower 3 by the carbon capture liquid supply equipment, is sprayed onto the flue gas by nozzles in the first spray tower 3, thereby cooling the flue gas. The cooled flue gas is obtained after the flue gas has been cooled by the first liquid collection medium at a first temperature in the first spray tower 3. The temperature of the cooled flue gas is lower than that of the flue gas after the pre-cooling operation.

[0037] Specifically, the pre-cooled flue gas enters the first spray tower 3 from the lower air inlet. Inside the first spray tower 3, it is cooled by a first liquid capturing medium with a first temperature, which is supplied by the carbon capture liquid supply device, to obtain the first portion of dry ice and cold flue gas. The first liquid capturing medium enters the first spray tower through the upper carbon capture liquid inlet located at the top of the first spray tower 3.

[0038] To better collect the dry ice, solid-liquid collection tanks (not shown in the figure) are respectively provided at the bottom of the first spray tower 3 and the second spray tower 4. In the first spray tower 3, a first portion of dry ice and a first portion of the liquid collection medium fall into the bottom solid-liquid collection tank and flow out of the first spray tower 3 from the bottom of the tank. After the first portion of dry ice flowing out of the first spray tower 3 liquefies, liquid carbon dioxide is obtained from the first portion of dry ice.

[0039] The cold flue gas output from the first spray tower 3 enters the second spray tower 4. Inside the second spray tower, it is cooled by a second liquid collection medium with a second temperature, which is supplied to the second spray tower 4 by the carbon capture liquid supply device. This cools the carbon dioxide in the cold flue gas to the sublimation temperature of carbon dioxide, resulting in the second portion of dry ice. After the second portion of dry ice liquefies, liquid carbon dioxide from the second portion of dry ice is obtained. The liquid carbon dioxide from the second portion of dry ice passes through the main heat exchanger 2 to obtain high-concentration liquid carbon dioxide. The first temperature is higher than the second temperature.

[0040] In one embodiment, the first temperature is higher than the second temperature, but both are lower than the sublimation temperature of carbon dioxide. Specifically, the cold flue gas is output from the top outlet of the first spray tower 3 and enters the second spray tower 4 from the lower inlet. Inside the second spray tower 4, it is cooled by the second liquid collecting medium with the second temperature, which is supplied to the second spray tower 4 by the carbon capture liquid supply device, to obtain the second portion of dry ice. The second liquid collecting medium enters the second spray tower 4 through the upper carbon capture liquid inlet located at the top of the second spray tower 4.

[0041] In the second spray tower 4, the second part of dry ice and part of the second liquid collection medium fall into the solid-liquid collection tank set in the second spray tower 4, and flow out of the second spray tower 4 from the bottom of the solid-liquid collection tank. After the second part of dry ice flowing out of the second spray tower 4 liquefies, liquid carbon dioxide of the second part of dry ice is obtained.

[0042] For example, if the first liquid trapping medium having a first temperature is a cryogenic isopentane liquid with a temperature of 168.15 K (-105 °C) and a carbon capture rate of 80%, then the second liquid trapping medium having a second temperature can be a cryogenic isopentane liquid with a temperature of 153.15 K (-120 °C) and a carbon capture rate of 90%, or a cryogenic isopentane liquid with a temperature of 138.15 K (-135 °C) and a carbon capture rate of 99%.

[0043] If the first liquid trapping medium with a first temperature is a cryogenic isopentane liquid with a temperature of 153.15 K (-120 °C) and a carbon capture rate of 90%, then the second liquid trapping medium with a second temperature can be a cryogenic isopentane liquid with a temperature of 138.15 K (-135 °C) and a carbon capture rate of 99%.

[0044] Moreover, the cold flue gas sent to the second spray tower contains little carbon dioxide and is at a low temperature, so the droplet mass of the second liquid trapping medium sprayed by the second spray tower is also less than the droplet mass of the first liquid trapping medium sprayed by the first spray tower.

[0045] In one implementation, the mass of the droplets can be adjusted according to the air intake, but the general principle is that the first liquid trapping medium sprayed by the first spray tower 3 produces more droplets than the second liquid trapping medium sprayed by the second spray tower 4, but the temperature of the first liquid trapping medium is higher than the temperature of the second liquid trapping medium.

[0046] Optionally, the droplet diameters of the first liquid trapping medium and the second liquid trapping medium are less than or equal to 2 mm.

[0047] As can be seen from the above description, the first spray tower 3 is larger in volume than the second spray tower 4, and the temperature of the first liquid collection medium in the first spray tower 3 is higher than that of the second liquid collection medium in the second spray tower 4. Therefore, by using the first spray tower 3 and the second spray tower 4 in series, the first spray tower 3 is used to remove most of the carbon dioxide from the flue gas, and the remainder then enters the second spray tower 4 where it is collected using a lower-temperature carbon capture liquid. For example, the first spray tower 3 can sublimate 80% of the carbon dioxide in the flue gas, and the second spray tower 4 can then sublimate the remaining 90% of the carbon dioxide in the cold flue gas. Of course, the carbon capture ratio of the first spray tower 3 and the second spray tower 4 can be freely adjusted according to actual needs, and carbon capture can also be performed entirely using the first spray tower 3. Therefore, the main purpose of using the first spray tower 3 and the second spray tower 4 in series for carbon dioxide capture is to make the carbon capture capacity of the carbon capture system more adjustable and to further save energy.

[0048] By setting the first spray tower 3 and the second spray tower 4 in a stepped manner, the carbon capture rate of the carbon capture system can reach 99%, which has the characteristics of higher carbon capture rate and energy saving.

[0049] To discharge the flue gas obtained after carbon capture operation from the first spray tower 3 and the second spray tower 4, the carbon capture system proposed in this embodiment further includes: a chimney connected to the main heat exchanger 2; the second spray tower 4, while obtaining the second portion of dry ice, also obtains the flue gas after carbon capture operation. After being discharged from the second spray tower 4, the flue gas undergoes heat exchange in the main heat exchanger 2 and is then discharged from the chimney. The flue gas after carbon capture operation is discharged from a top outlet located at the top of the second spray tower 4.

[0050] The main heat exchanger 2 performs heat exchange on the flue gas after the carbon capture operation (i.e., the flue gas discharged from the top outlet of the second spray tower 4), recovering the cold energy carried by the flue gas after the carbon capture operation. The recovered cold energy is used to pre-cool the flue gas after it has been dehydrated in the drying tower. This allows for the recycling of the cold energy carried by the flue gas after the carbon capture operation, maximizing carbon dioxide capture efficiency while minimizing the consumption of carbon capture liquid, thus offering advantages such as being green, environmentally friendly, and energy-saving.

[0051] In order to input a first liquid capture medium with a first temperature into the first spray tower 3 and a second liquid capture medium with a second temperature into the second spray tower 4, specifically, in the carbon capture system proposed in this embodiment, the carbon capture liquid supply device includes: a first refrigeration heat exchanger 8 and a second refrigeration heat exchanger 13; the first refrigeration heat exchanger 8 is connected to the first spray tower 3; and the second refrigeration heat exchanger 13 is connected to the second spray tower 4.

[0052] The first refrigeration heat exchanger 8 is capable of feeding a first liquid collection medium with a first temperature into the first spray tower 3. The second refrigeration heat exchanger 13 is capable of feeding a second liquid collection medium with a second temperature into the second spray tower 4.

[0053] To replenish the second liquid capture medium in the second refrigeration heat exchanger 13, a carbon capture liquid replenishment inlet is provided on the second refrigeration heat exchanger 13. By providing a carbon capture liquid replenishment inlet on the second refrigeration heat exchanger 13, the carbon capture liquid carried away or evaporated by the flue gas can be replenished, thereby ensuring the carbon capture efficiency of the carbon capture system.

[0054] To liquefy the dry ice flowing out of the first spray tower 3 and the second spray tower 4, it is necessary to first separate the mixture of the first portion of dry ice and the first liquid capturing medium flowing out of the first spray tower 3, and the mixture of the second portion of dry ice and the second liquid capturing medium flowing out of the second spray tower 4, respectively. That is, it is necessary to separate the dry ice and carbon capture liquid flowing out of the spray tower equipment. In order to separate the dry ice and carbon capture liquid flowing out of the spray tower equipment, the carbon capture system proposed in this embodiment also includes: a circulating pump 5, a solid-liquid separator 6, and a melting pump 7.

[0055] The circulating pump 5 is connected to the first spray tower 3, the second spray tower 4 and the solid-liquid separator 6 respectively; the solid-liquid separator 6 is also connected to the first refrigeration heat exchanger 8 and the melting pump 7; the melting pump 7 is also connected to the main heat exchanger 2.

[0056] The circulating pump 5 is used to transport the mixture of dry ice and part of the carbon capture liquid flowing out of the spray tower equipment to the solid-liquid separator 6.

[0057] Solid-liquid separator 6 is used to separate dry ice from carbon capture liquid by crushing.

[0058] The melting pump 7 is used to liquefy dry ice into liquid carbon dioxide and send the liquid carbon dioxide into the main heat exchanger 2 for cold energy recovery.

[0059] The mixture of dry ice and carbon capture liquid flows out from the bottom of the first spray tower and the bottom of the second spray tower, respectively. After passing through the circulation pump 5, it enters the solid-liquid separator 6 for solid-liquid separation, separating the dry ice and the carbon capture liquid from the mixture.

[0060] Optionally, the solid-liquid separator 6 separates the dry ice and carbon capture liquid from the mixture of dry ice and carbon capture liquid by crushing.

[0061] The separated dry ice is transported to the melting pump 7, where it is heated and liquefied to obtain liquid carbon dioxide. The liquid carbon dioxide then enters the main heat exchanger 2, where its cooling capacity is recovered to obtain high-concentration liquid carbon dioxide. This allows for the recycling of the cooling capacity carried by the stored liquid carbon dioxide. While capturing carbon dioxide, the cooling capacity of the liquid carbon dioxide can also be recycled, and the recovered cooling capacity can be used to pre-cool the flue gas, offering advantages such as green environmental protection and energy saving.

[0062] The separated carbon capture liquid is fed into the first refrigeration heat exchanger, where it is cooled to a first temperature. The carbon capture liquid is then transported to the first spray tower to condense the flue gas. By feeding the separated carbon capture liquid into the first refrigeration heat exchanger, a portion of the carbon capture liquid exiting the spray tower is recycled, minimizing the amount of carbon capture liquid needed for replenishment and reducing the operating cost of the carbon capture system.

[0063] When liquid carbon dioxide passes through the main heat exchanger, the heat exchanger performs a heat exchange operation on the passing liquid carbon dioxide, recovering the cold energy carried by the liquid carbon dioxide. This recovered cold energy is then used to pre-cool the flue gas after it has passed through the drying tower for dehydration. This allows for the recycling of the cold energy carried by the liquid carbon dioxide to be stored. Simultaneously with carbon dioxide capture, the cold energy within the liquid carbon dioxide can be recycled and used to pre-cool the flue gas, offering advantages such as being green, environmentally friendly, and energy-saving.

[0064] In order to cool and recycle a portion of the carbon capture liquid flowing out of the spray tower equipment, the carbon capture system proposed in this embodiment further includes: a first compressor 9, a second compressor 11, a first throttle valve 10, and a second throttle valve 12; the first compressor 9 and the first throttle valve 10 are interconnected and respectively connected to the first refrigeration heat exchanger 8; the second compressor 11 and the second throttle valve 12 are interconnected and respectively connected to the second refrigeration heat exchanger 13.

[0065] Specifically, the first refrigeration heat exchanger 8 and the second refrigeration heat exchanger 13 are respectively provided with a refrigerant outlet and a refrigerant inlet; wherein, the refrigerant outlet of the first refrigeration heat exchanger 8 is connected to one side of the first compressor 9 through a first throttle valve 10, and the other side of the first compressor is connected to the refrigerant inlet of the first refrigeration heat exchanger 13. The refrigerant outlet of the second refrigeration heat exchanger 13 is connected to one side of the second compressor 12 through a second throttle valve 12, and the other side of the second compressor 12 is connected to the refrigerant inlet of the second refrigeration heat exchanger 13.

[0066] By setting a first compressor 9 and a first throttle valve 10 connected to the first refrigeration heat exchanger 8, the refrigerant output by the first compressor 9 is used to cool part of the carbon capture liquid flowing out of the spray tower equipment to a first temperature, thereby achieving the purpose of recycling part of the carbon capture liquid flowing out of the spray tower equipment.

[0067] The second refrigeration heat exchanger 13, the second compressor 12, and the second throttle valve 11 cool the isopentane liquid by exchanging heat with the refrigerant, and replenish the isopentane liquid externally. The temperature of the second liquid capturing medium sprayed by the second spray tower is lower than the temperature of the first liquid capturing medium sprayed by the first spray tower. Considering the temperature differences in the storage or use of the various carbon capturing liquids mentioned above, the second compressor 12 is used to uniformly cool them down again, ensuring that the temperature of the second liquid capturing medium sprayed by the second spray tower reaches -120℃ or -135℃, thereby ensuring a higher carbon capture rate.

[0068] This application proposes a carbon capture system that uses a spray tower to directly spray carbon capture liquid onto pre-cooled flue gas. Carbon dioxide is captured by sublimation using the carbon capture liquid, and the resulting dry ice is carried out of the spray tower by the carbon capture liquid, avoiding problems such as collection difficulties caused by dry ice condensation on the spray tower walls and the dry ice layer affecting heat conduction. Furthermore, by using a first and second spray tower in series, each using carbon capture liquid at different temperatures, the carbon capture efficiency is improved while reducing refrigeration consumption. This allows the entire carbon capture system to select different capture methods based on actual needs. Moreover, by incorporating a main heat exchanger, the flue gas can be pre-cooled, and the cooling capacity of the decarbonized flue gas and liquid carbon dioxide can be recovered, ultimately providing a high-concentration liquid carbon dioxide for easy storage.

[0069] In summary, this embodiment proposes a carbon capture system that utilizes a main heat exchanger to pre-cool the flue gas after dehydration in a drying tower. Compared to related technologies that use carbon capture liquid to sublimate high-temperature flue gas, which leads to significant evaporation of the carbon capture liquid, pre-cooling the flue gas before it enters the spray tower reduces its temperature. As the flue gas cools to its carbon dioxide sublimation temperature by the carbon capture liquid, the reduced temperature difference between the flue gas and the carbon capture liquid decreases, thus reducing the amount of carbon capture liquid evaporated. Furthermore, the spray tower collects the dry ice formed by the sublimation of carbon dioxide in the flue gas, minimizing the drawbacks of dry ice collection difficulties, equipment corrosion, and poor thermal conductivity associated with using box-type low-temperature carbon capture equipment.

[0070] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A carbon capture system, characterized in that, include: Drying tower, main heat exchanger, spray tower equipment and carbon capture liquid supply equipment; The drying tower, the main heat exchanger, the spray tower equipment, and the carbon capture liquid supply equipment are connected in sequence; The flue gas dehydrated by the drying tower enters the main heat exchanger, which pre-cools the flue gas. The pre-cooled flue gas then enters the spray tower, where it is cooled by the carbon capture liquid supplied by the carbon capture liquid supply device. This cools the carbon dioxide in the flue gas to its sublimation temperature to obtain dry ice. The dry ice is then liquefied to obtain liquid carbon dioxide. After passing through the main heat exchanger, the liquid carbon dioxide is stored at a high concentration. The carbon capture liquid includes: a first liquid capture medium and a second liquid capture medium; the dry ice includes: a first portion of dry ice and a second portion of dry ice. The spray tower equipment includes: a first spray tower and a second spray tower; The first spray tower is connected to the main heat exchanger and the second spray tower respectively, and the first spray tower and the second spray tower are respectively connected to the carbon capture liquid supply equipment; The pre-cooled flue gas enters the first spray tower, where it is cooled by a first liquid collection medium with a first temperature, which is supplied by the carbon capture liquid supply device. This cools the carbon dioxide in the flue gas to its sublimation temperature, resulting in the first portion of dry ice and cold flue gas. The first portion of dry ice is liquefied to obtain liquid carbon dioxide from the first portion of dry ice. After passing through the main heat exchanger, the liquid carbon dioxide from the first portion of dry ice is converted into high-concentration liquid carbon dioxide. The cold flue gas is then fed into the second spray tower. The cold flue gas enters the second spray tower, where it is cooled by a second liquid collection medium with a second temperature, which is supplied by the carbon capture liquid supply device. This cools the carbon dioxide in the cold flue gas to its sublimation temperature, resulting in the second portion of dry ice. The second portion of dry ice is then liquefied to obtain liquid carbon dioxide. This liquid carbon dioxide from the second portion of dry ice passes through the main heat exchanger to obtain a high concentration of liquid carbon dioxide. The first temperature is higher than the second temperature. The main heat exchanger is used to pre-cool the dried flue gas, reduce the flue gas temperature, reduce the evaporation of carbon capture liquid in the next step, and recover the cooling capacity of the decarbonized flue gas and the liquid carbon dioxide.

2. The carbon capture system according to claim 1, characterized in that, Also includes: The chimney is connected to the main heat exchanger; While obtaining the second portion of dry ice, the second spray tower can also obtain the flue gas after the carbon capture operation. After being discharged from the second spray tower, the flue gas after the carbon capture operation passes through the heat exchanger of the main heat exchanger and is then discharged from the chimney. The main heat exchanger performs heat exchange on the flue gas after the carbon capture operation and recovers the cold energy carried by the flue gas after the carbon capture operation. The recovered cold energy is used to pre-cool the flue gas after it has been dehydrated by the drying tower.

3. The carbon capture system according to claim 1, characterized in that, The carbon capture liquid supply device includes: a first refrigeration heat exchanger 8 and a second refrigeration heat exchanger 13; The first refrigeration heat exchanger is connected to the first spray tower; the second refrigeration heat exchanger is connected to the second spray tower. The first refrigeration heat exchanger is capable of inputting a first liquid capture medium with a first temperature into the first spray tower; The second refrigeration heat exchanger is capable of inputting a second liquid collection medium with a second temperature into the second spray tower.

4. The carbon capture system according to claim 3, characterized in that, Also includes: Circulating pumps, solid-liquid separators, and melting pumps; The circulating pump is connected to the first spray tower, the second spray tower, and the solid-liquid separator, respectively; the solid-liquid separator is also connected to the first refrigeration heat exchanger and the melting pump; the melting pump is also connected to the main heat exchanger. The mixture of dry ice and carbon capture liquid flows out from the bottom of the first spray tower and the bottom of the second spray tower, respectively. After passing through the circulation pump, it enters the solid-liquid separator for solid-liquid separation, and the dry ice and carbon capture liquid are separated from the mixture of dry ice and carbon capture liquid. The separated dry ice is transported to the melting pump, where it is heated and liquefied to obtain liquid carbon dioxide. The liquid carbon dioxide then enters the main heat exchanger, where it undergoes heat recovery to obtain high-concentration liquid carbon dioxide. The separated carbon capture liquid is fed into the first refrigeration heat exchanger. After being cooled to a first temperature by the first refrigeration heat exchanger, the carbon capture liquid is transported to the first spray tower to condense the flue gas in the first spray tower.

5. The carbon capture system according to claim 4, characterized in that, The main heat exchanger performs heat exchange operations on the passing liquid carbon dioxide, and recovers the cold energy carried in the liquid carbon dioxide through the heat exchange operation. The recovered cold energy is used to pre-cool the flue gas that has passed through the drying tower for dehydration.

6. The carbon capture system according to claim 4, characterized in that, The solid-liquid separator separates the dry ice and the carbon capture liquid from the mixture of the dry ice and the carbon capture liquid by crushing.

7. The carbon capture system according to claim 3, characterized in that, The second refrigeration heat exchanger is equipped with a carbon capture liquid replenishment inlet.

8. The carbon capture system according to claim 3, characterized in that, Also includes: First compressor, second compressor, first throttle valve and second throttle valve; The first compressor and the first throttle valve are interconnected and are also connected to the first refrigeration heat exchanger. The second compressor and the second throttle valve are interconnected and are also connected to the second refrigeration heat exchanger.

9. The carbon capture system according to any one of claims 1-8, characterized in that, The carbon capture solution is isopentane liquid or isopentane-n-pentane mixed liquid.

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