Regeneration tower and regeneration method for capturing CO2 from flue gas, and system for capturing CO2 from flue gas

Abstract

This invention relates to the field of flue gas purification technology, and discloses a regeneration tower and regeneration method for capturing CO2 from flue gas, as well as a system for capturing CO2 from flue gas. The regeneration tower includes a first inlet and a second inlet; the first inlet is located at the top of the regeneration tower; the second inlet is located below the first inlet, and the number of trays between the first inlet and the second inlet accounts for 20%-55% of the total number of trays. The regeneration method for capturing CO2 from flue gas includes regenerating and desorbing a pretreated CO2 absorbent in the regeneration tower. This method can significantly reduce the heat energy consumption of capturing carbon dioxide from flue gas using the amine method, thereby improving the economic efficiency of capturing carbon dioxide from flue gas.

Description

Technical Field

[0001] This invention relates to the field of flue gas purification technology in industries such as petrochemicals, power, steel, and cement, and specifically to a regeneration tower and regeneration method for capturing CO2 in flue gas, as well as a system for capturing CO2 in flue gas. Background Technology

[0002] As global temperatures continue to rise, posing a significant threat to human society and the Earth's natural environment, carbon emissions are a major contributing factor. China ranks first in the world in carbon emissions, with a high emission intensity. Its carbon emission structure is directly linked to its traditional resource endowment, with coal-fired power plants, steel, and cement accounting for more than 60% of the country's total emissions.

[0003] Large-scale carbon dioxide capture has become a key task and urgent need for major industries or fields such as power, cement, steel, and petrochemicals. Carbon dioxide capture, utilization and storage (CCUS) has become a hot topic, with flue gas capture being the most critical link.

[0004] Currently, the most mature flue gas carbon dioxide capture technology developed both domestically and internationally is the alcohol amine method. This technology has been successfully implemented on an industrial scale, but its operating cost is relatively high, mainly due to the high heat consumption during carbon dioxide regeneration.

[0005] The main process flow of the amine-based carbon dioxide capture technology includes: 1. Flue gas enters the absorption tower, where carbon dioxide in the flue gas is absorbed by the amine solution at 40℃; 2. The amine solution after absorbing carbon dioxide enters the regeneration tower, where carbon dioxide is desorbed at 110℃; 3. The amine solution forms a cycle between the absorption tower and the regeneration tower. However, to achieve the desorption and regeneration temperature of 110℃, heat must be provided to the regeneration tower, which is the main heat consumption for capturing carbon dioxide from flue gas. Currently, without other external energy-saving measures, the heat consumption for capturing 1 ton of carbon dioxide is 2.8 GJ, which is very high, resulting in low efficiency and poor economic viability.

[0006] Therefore, reducing the heat consumption of carbon dioxide capture and improving economic efficiency has become the focus of current research and development. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of low regeneration efficiency and high heat consumption of carbon dioxide in flue gas in existing technologies, and to provide a regeneration tower and regeneration method for capturing CO2 in flue gas, as well as a system for capturing CO2 in flue gas. This method can significantly reduce the heat energy consumption of carbon dioxide capture in flue gas using the amine method, thereby improving the economic efficiency of capturing carbon dioxide in flue gas.

[0008] To achieve the above objectives, the first aspect of the present invention provides a regeneration tower for capturing CO2 in flue gas, wherein the regeneration tower includes a first feed inlet and a second feed inlet;

[0009] The first feed inlet is located at the top of the regeneration tower;

[0010] The second feed inlet is located below the first feed inlet, and the number of trays between the first feed inlet and the second feed inlet accounts for 20%-55% of the total number of trays.

[0011] A second aspect of the present invention provides a method for regenerating CO2 captured in flue gas, wherein the method includes regenerating and desorbing a pretreated CO2-rich absorbent in a regeneration tower as described in the first aspect of the present invention.

[0012] A third aspect of the present invention provides a system for capturing CO2 in flue gas, wherein the system includes an absorption tower and a regeneration tower as described in the first aspect of the present invention.

[0013] Through the above technical solution, the present invention achieves the following technical effects:

[0014] This invention adds a second inlet to the regeneration tower for CO2-rich absorbent liquid and limits its location, controlling the temperature and feed rate of the second inlet. This allows the rich absorbent liquid to enter from the upper middle part of the regeneration tower, enabling the rich absorbent liquid to undergo sufficient regeneration and desorption in the regeneration tower, while also making full use of the regeneration heat of the regeneration tower. This significantly reduces the heat energy consumption of carbon dioxide capture in the amine method, improves regeneration efficiency, and enhances the economic benefits of carbon dioxide capture in flue gas. Attached Figure Description

[0015] Figure 1 This is a structural diagram of a CO2 regeneration tower.

[0016] Figure 2 It is a regeneration device for capturing CO2 solutions from flue gas.

[0017] Explanation of reference numerals in the attached figures

[0018] 1. Absorber 2. Cooler 3. Rich liquid pump

[0019] 4. Heat exchanger 5. Lean liquid pump 6. Regeneration tower Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] To achieve the above objectives, the first aspect of the present invention provides a regeneration tower for capturing CO2 in flue gas, the regeneration tower including a first inlet and a second inlet;

[0022] The first feed inlet is located at the top of the regeneration tower;

[0023] The second feed inlet is located below the first feed inlet, and the number of trays between the first feed inlet and the second feed inlet accounts for 20%-55% of the total number of trays.

[0024] In this invention, the volume of the regeneration tower is not particularly limited, and can be increased or decreased according to actual production needs. To clearly describe the positions of the first and second feed inlets on the regeneration tower, those skilled in the art typically describe the feed inlet positions using the position of the tray within the regeneration tower. For example... Figure 1 As shown, the first feed inlet is located at the top of the regeneration tower; feed inlets two through eight are located below the first feed inlet, and any one of them can be the location of the second feed inlet.

[0025] In this invention, the inventors discovered that increasing the second feed inlet of the rich liquid entering the regeneration tower can reduce the heat consumption of CO2 capture in flue gas using the amine method. Specifically, the inventors found that with staged feeding, when CO2 absorbs the rich liquid in the absorption tower and simultaneously enters the regeneration tower from both the first and second feed inlets, the regeneration and desorption process of the CO2 absorbent at the lower end of the regeneration tower is more thorough. Simultaneously, excess heat is used to desorb the CO2 absorbent at the upper end of the regeneration tower, ensuring full utilization of the system's heat. This allows for the desorption of more carbon dioxide while providing the same heat source, thereby reducing the heat consumption of CO2 capture in flue gas and improving economic efficiency. Furthermore, with the position of the second feed inlet... As the feed inlet is gradually moved downwards, for example from inlet number two to inlet number six, the CO2 absorbent at the bottom of the regeneration tower undergoes more thorough regeneration and desorption. Excess heat is used to desorb the upper absorbent, resulting in the desorption of more CO2 and further reducing heat consumption. However, as the second feed inlet is moved further downwards, for example from inlet number six to inlet number seven or eight, the residence time of the CO2 absorbent in the regeneration tower becomes too short, leading to insufficient heat exchange and regeneration desorption. Consequently, the amount of carbon dioxide desorbed decreases again, causing the heat consumption per ton of carbon dioxide to rise again. Ideally, the second feed inlet should be inlet number four or five.

[0026] In this invention, preferably, the number of trays between the first feed inlet and the second feed inlet accounts for 30%-40% of the total number of trays.

[0027] In this invention, the number of trays in the regeneration tower is designed to meet the regeneration requirements. Preferably, the number of trays in the regeneration tower is 10-40.

[0028] In this invention, when the first feed inlet and the second feed inlet meet the above-mentioned range, the rich absorbent liquid can be fully regenerated and desorbed in the regeneration tower, and the regeneration heat of the regeneration tower can be fully utilized, thereby significantly reducing the heat energy consumption of carbon dioxide capture in flue gas by the amine method, improving the regeneration efficiency, and improving the economic benefits of carbon dioxide capture in flue gas.

[0029] In this invention, in order to further improve the regeneration and desorption of CO2 absorbent in the regeneration tower and increase the CO2 flow rate at the top outlet of the regeneration tower, it is necessary to limit the temperature and injection volume of the feed inlet.

[0030] According to some embodiments of the present invention, the first feed inlet and the second feed inlet are respectively provided with temperature controllers, such that the temperature of the first feed inlet is 90-110°C and the temperature of the second feed inlet is 90-110°C.

[0031] In a preferred embodiment, the temperature of the first feed inlet and the second feed inlet is 95-105℃.

[0032] According to some embodiments of the present invention, the first feed port and the second feed port are respectively provided with a metering device, and the volume ratio of the feed amount of the second feed port to the feed amount of the first feed port is 2-6:1, preferably the volume ratio of the feed amount of the second feed port to the feed amount of the first feed port is 3-4:1.

[0033] In this invention, when the temperature and injection rate of the feed inlet meet the above conditions, the CO2 absorbent can be fully regenerated and desorbed in the regeneration tower.

[0034] In this invention, the temperature at the bottom of the regeneration tower affects the amount of CO2 desorbed during regeneration.

[0035] According to some embodiments of the present invention, the temperature at the bottom of the regeneration tower is 105-115°C.

[0036] A second aspect of the present invention provides a method for regenerating CO2 captured by flue gas, the method comprising regenerating and desorbing a pretreated CO2-rich absorbent in a regeneration tower as described in the first aspect of the present invention.

[0037] In this invention, the flue gas refers to gases produced by industries such as petrochemicals, power generation, steel, and cement. Based on the total volume of the flue gas, it contains 8 vol%-16 vol% CO2, 4 vol%-10 vol% O2, and 70 vol%-88 vol% N2.

[0038] In this invention, the pretreatment method includes: passing flue gas into an absorption tower containing CO2 absorbent, whereby the absorbent absorbs CO2 from the flue gas to obtain a CO2-rich absorbent solution.

[0039] According to some embodiments of the present invention, the pretreatment conditions include: a temperature of 95-105°C and a pressure of 20-70 kPa.

[0040] According to some embodiments of the present invention, the absorbent is selected from C2-C6 alkanolamines and / or C2-C6 polyamines, and preferably, the absorbent is selected from at least one of ethanolamine, methylmonoethanolamine, methyldiethanolamine, isopropanolamine and diethylenetriamine.

[0041] In this invention, such as Figure 2 As shown, the CO2 absorbent at the bottom of the absorber 1 enters the regeneration tower 6 through the rich liquid pump 3 via inlet 1 and inlets 2-8 at the top. It flows from the top to the bottom of the regeneration tower 6, and through heat exchange with the heat source at the bottom of the regeneration tower 6, the carbon dioxide and water in the absorbent are converted into gas and regenerated and desorbed from the regeneration tower 6, and discharged from the top of the regeneration tower 6. The regenerated absorbent is discharged from the bottom of the regeneration tower 6, thus completing the regeneration and desorption process of the CO2 absorbent.

[0042] A third aspect of the present invention provides a regeneration system for capturing CO2 in flue gas, the system comprising an absorption tower 1 and a regeneration tower 6 as described in the first aspect.

[0043] According to some embodiments of the present invention, the system further includes a cooler 2, a rich liquid pump 3, a lean liquid pump 5, and a heat exchanger 4.

[0044] In a preferred embodiment, the rich liquid pump 3 is connected to the bottom of the absorption tower 1 and the top of the regeneration tower 6, respectively; the lean liquid pump 5 is connected to the top of the absorption tower 1 and the bottom of the regeneration tower 6, respectively.

[0045] According to a particularly preferred embodiment of the present invention, the present invention provides a method for regenerating CO2 captured in flue gas. Using... Figure 2 The regeneration device shown is used, and the specific operating method includes:

[0046] The bottom of regeneration tower 6 provides a heat source of 2800 kJ / h. The absorbent liquid from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters regeneration tower 6 through inlet No. 1 and inlets No. 4 to No. 6 respectively (e.g., ...). Figure 1 The feed temperature at inlet 1 is 95-105℃, and the feed temperatures at inlets 4 to 6 are also 95-105℃. The volume ratio of the feed rate at the second inlet to that at the first inlet is 3-4:1. The absorbent after regeneration and desorption from regeneration tower 6 flows out from the bottom of regeneration tower 6 and enters the top of absorption tower 1 via lean liquid pump 5 for recycling. The temperature at the bottom of regeneration tower 6 is 105-115℃. The flow rate of carbon dioxide at the top outlet of regeneration tower 6 is measured, and the heat consumption per ton of carbon dioxide is calculated.

[0047] The present invention will be described in detail below through embodiments.

[0048] In the following examples, the heat consumption per ton of carbon dioxide is calculated using the following formula:

[0049]

[0050] All raw materials used in this embodiment are commercially available products.

[0051] Example 1

[0052] This invention provides a method for regenerating flue gas to capture CO2. It employs... Figure 2 The regeneration device shown has 20 trays in its regeneration tower. The specific operating method includes:

[0053] The bottom of regeneration tower 6 provides a heat source of 2800 kJ / h. The absorbent liquid from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters regeneration tower 6 through inlet 1 and inlet 2 respectively (e.g., Figure 1 The number of trays at feed inlet 2 accounts for 20% of the total number of trays. The feed temperature at feed inlet 1 is 98℃, and the feed rate is 5 L / h. The feed temperature at feed inlet 2 is 98℃, and the feed rate is 15 L / h. The measured flow rate of carbon dioxide at the top outlet of regeneration tower 6 is 0.56 m³ / h. 3 The absorbent after regeneration and desorption from regeneration tower 6 flows out from the bottom of regeneration tower 6 and enters the top of absorption tower 1 via lean liquid pump 5 for recycling. The temperature at the bottom of regeneration tower 6 is 110℃. The calculated heat consumption per ton of carbon dioxide is 2.59 GJ.

[0054] Example 2

[0055] This invention provides a method for regenerating flue gas to capture CO2. It employs... Figure 2 The regeneration device shown has 20 trays in its regeneration tower. The specific operating method includes:

[0056] The bottom of regeneration tower 6 provides a heat source of 2800 kJ / h. The absorbent liquid from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters regeneration tower 6 through inlet 1 and inlet 3 respectively (e.g., Figure 1 The number of trays at feed inlet 3 accounts for 25% of the total number of trays. The feed temperature at feed inlet 1 is 98℃, and the feed rate is 5 L / h. The feed temperature at feed inlet 3 is 98℃, and the feed rate is 15 L / h. The measured flow rate of carbon dioxide at the top outlet of regeneration tower 6 is 0.56 m³ / h. 3 The absorbent after regeneration and desorption from regeneration tower 6 flows out from the bottom of regeneration tower 6 and enters the top of absorption tower 1 via lean liquid pump 5 for recycling. The temperature at the bottom of regeneration tower 6 is 110℃. The calculated heat consumption per ton of carbon dioxide is 2.40 GJ.

[0057] Example 3

[0058] This invention provides a method for regenerating flue gas to capture CO2. It employs... Figure 2 The regeneration device shown has 20 trays in its regeneration tower. The specific operating method includes:

[0059] The bottom of regeneration tower 6 provides a heat source of 2800 kJ / h. The absorbent liquid from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters regeneration tower 6 through inlet No. 1 and inlet No. 4 respectively (e.g., Figure 1 The number of trays at feed inlet 4 accounts for 30% of the total number of trays. The feed temperature at feed inlet 1 is 98℃, and the feed rate is 5 L / h. The feed temperature at feed inlet 4 is 98℃, and the feed rate is 15 L / h. The measured flow rate of carbon dioxide at the top outlet of regeneration tower 6 is 0.65 m³ / h. 3The absorbent after regeneration and desorption from regeneration tower 6 flows out from the bottom of regeneration tower 6 and enters the top of absorption tower 1 via lean liquid pump 5 for recycling. The temperature at the bottom of regeneration tower 6 is 110℃. The calculated heat consumption per ton of carbon dioxide is 2.15 GJ.

[0060] Example 4

[0061] This invention provides a method for regenerating flue gas to capture CO2. It employs... Figure 2 The regeneration device shown has 20 trays in its regeneration tower. The specific operating method includes:

[0062] The bottom of regeneration tower 6 provides a heat source of 2800 kJ / h. The absorbent liquid from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters regeneration tower 6 through inlet No. 1 and inlet No. 5 respectively (e.g., Figure 1 The number of trays at feed inlet 5 accounts for 40% of the total number of trays. The feed temperature at feed inlet 1 is 98℃, and the feed rate is 5 L / h. The feed temperature at feed inlet 5 is 98℃, and the feed rate is 15 L / h. The measured flow rate of carbon dioxide at the top outlet of regeneration tower 6 is 0.65 m³ / h. 3 The absorbent after regeneration and desorption from regeneration tower 6 flows out from the bottom of regeneration tower 6 and enters the top of absorption tower 1 via lean liquid pump 5 for recycling. The temperature at the bottom of regeneration tower 6 is 110℃. The calculated heat consumption per ton of carbon dioxide is 2.15 GJ.

[0063] Example 5

[0064] This invention provides a method for regenerating flue gas to capture CO2. It employs... Figure 2 The regeneration device shown has 20 trays in its regeneration tower. The specific operating method includes:

[0065] The bottom of regeneration tower 6 provides a heat source of 2800 kJ / h. The absorbent liquid from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters regeneration tower 6 through inlet No. 1 and inlet No. 6 respectively (e.g., Figure 1 The number of trays at feed inlet 6 accounts for 45% of the total number of trays. The feed temperature at feed inlet 1 is 98℃, and the feed rate is 5 L / h. The feed temperature at feed inlet 6 is 98℃, and the feed rate is 15 L / h. The measured flow rate of carbon dioxide at the top outlet of regeneration tower 6 is 0.60 m³ / h. 3 The absorbent after regeneration and desorption from regeneration tower 6 flows out from the bottom of regeneration tower 6 and enters the top of absorption tower 1 via lean liquid pump 5 for recycling. The temperature at the bottom of regeneration tower 6 is 110℃. The calculated heat consumption per ton of carbon dioxide is 2.33 GJ.

[0066] Example 6

[0067] This invention provides a method for regenerating flue gas to capture CO2. It employs... Figure 2The regeneration device shown has 20 trays in its regeneration tower. The specific operating method includes:

[0068] The bottom of regeneration tower 6 provides a heat source of 2800 kJ / h. The absorbent liquid from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters regeneration tower 6 through inlet 1 and inlet 7 respectively (e.g., Figure 1 The number of trays at feed inlet 7 accounts for 50% of the total number of trays. The feed temperature at feed inlet 1 is 98℃, and the feed rate is 5 L / h. The feed temperature at feed inlet 7 is 98℃, and the feed rate is 15 L / h. The measured flow rate of carbon dioxide at the top outlet of regeneration tower 6 is 0.56 m³ / h. 3 The absorbent after regeneration and desorption from regeneration tower 6 flows out from the bottom of regeneration tower 6 and enters the top of absorption tower 1 via lean liquid pump 5 for recycling. The temperature at the bottom of regeneration tower 6 is 110℃. The calculated heat consumption per ton of carbon dioxide is 2.50 GJ.

[0069] Example 7

[0070] This invention provides a method for regenerating flue gas to capture CO2. It employs... Figure 2 The regeneration device shown is used, and the specific operating method includes:

[0071] The bottom of regeneration tower 6 provides a heat source of 2800 kJ / h. The absorbent liquid from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters regeneration tower 6 through inlet No. 1 and inlet No. 8 respectively (e.g., Figure 1 The number of trays at feed inlet 8 accounts for 55% of the total number of trays. The feed temperature at feed inlet 1 is 98℃, and the feed rate is 5 L / h. The feed temperature at feed inlet 8 is 98℃, and the feed rate is 15 L / h. The measured flow rate of carbon dioxide at the top outlet of regeneration tower 6 is 0.56 m³ / h. 3 The absorbent after regeneration and desorption from regeneration tower 6 flows out from the bottom of regeneration tower 6 and enters the top of absorption tower 1 via lean liquid pump 5 for recycling. The temperature at the bottom of regeneration tower 6 is 110℃. The calculated heat consumption per ton of carbon dioxide is 2.50 GJ.

[0072] Example 8

[0073] The method is the same as in Example 1, except that the absorbent from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters from inlet 3 and inlet 4 of regeneration tower 6 respectively (e.g., Figure 1 The flow rate of carbon dioxide at the top outlet of regeneration tower 6 was measured to be 0.46 m³ / s. 3 / h, the calculated heat consumption per ton of carbon dioxide is 3.1GJ.

[0074] Example 9

[0075] The method was the same as in Example 1, except that the feed rate at inlet 1 was 10 L / h, the feed rate at inlet 2 was 10 L / h, and the carbon dioxide flow rate at the top outlet of regeneration tower 6 was measured to be 0.32 m³ / h. 3 / h, the calculated heat consumption per ton of carbon dioxide is 4.5GJ.

[0076] Example 10

[0077] The method was the same as in Example 1, except that the temperature of the first inlet was 85°C, the temperature of the second inlet was 85°C, and the flow rate of carbon dioxide at the top outlet of regeneration tower 6 was measured to be 0.46 m³ / s. 3 / h, the calculated heat consumption per ton of carbon dioxide is 3.1GJ.

[0078] Comparative Example 1

[0079] A conventional method for regenerating CO2 from flue gas is provided. The specific operation includes:

[0080] The bottom of regeneration tower 6 provides a heat source of 2800 kJ / h. The absorbent liquid from absorption tower 1, after absorbing carbon dioxide through heat exchanger 4, enters regeneration tower 6 through inlet No. 1. The inlet temperature is 98℃, and the feed rate is 20 L / h. The measured flow rate of carbon dioxide at the top outlet of regeneration tower 6 is 0.5 m³ / h. 3 The absorbent after regeneration and desorption from regeneration tower 6 flows out from the bottom of regeneration tower 6 and enters the top of absorption tower 1 via lean liquid pump 5 for recycling. The temperature at the bottom of regeneration tower 6 is 110℃. The calculated heat consumption per ton of carbon dioxide is 2.80 GJ.

[0081] As can be seen from Examples 1-7 and Comparative Example 1, with segmented feeding, the first inlet position remains relatively fixed while the second inlet position moves downwards. This makes the regeneration and desorption process of the CO2 absorbent at the lower end in the regeneration tower more thorough. Simultaneously, excess heat desorbs the CO2 absorbent at the upper part of the regeneration tower, resulting in the desorption of more carbon dioxide. Examples 1 and 2 show that as the second inlet position moves downwards, the heat consumption per ton of carbon dioxide decreases to 2.59 GJ and 2.40 GJ respectively, representing a decrease of 7.5% and 14.29% compared to Comparative Example 1 (conventional desorption method). Examples 3-4 show that as the second inlet position continues to move downwards, the heat consumption per ton of carbon dioxide decreases to its lowest level, 2.15 GJ, representing a decrease of 23.21% compared to Comparative Example 1 (conventional desorption method).

[0082] As shown in Examples 5-7, with the continued downward movement of the second inlet, the residence time of the CO2 absorbent in the regeneration tower is too short, resulting in insufficient heat exchange and regeneration desorption. Consequently, the amount of carbon dioxide desorbed decreases, leading to a rebound in heat consumption per ton of carbon dioxide (compared to Examples 3-4), at 2.33 GJ, 2.50 GJ, and 2.50 GJ respectively. However, compared to Comparative Example 1 (traditional desorption method), the heat consumption for desorbing one ton of carbon dioxide in Examples 5-7 decreased by 16.79%, 10.14%, and 10.14%, respectively. Therefore, the solution must enter the regeneration tower at a suitable location to minimize regeneration heat consumption and improve economic efficiency.

[0083] As shown in Example 8, as the positions of the first and second inlets move downward, the residence time of the CO2 absorbent in the regeneration tower is too short, resulting in insufficient heat exchange and regeneration desorption. The amount of carbon dioxide desorbed during regeneration continues to decrease, causing the heat consumption per ton of carbon dioxide to continue to rise (3.1 GJ). As shown in Examples 9-10, changing the temperature and feed rate of the first and second inlets respectively causes the heat consumption per ton of carbon dioxide to continue to rise, reaching 4.5 GJ and 3.1 GJ respectively.

[0084] In Comparative Example 1, the feed position of the solution is the highest compared to the feed position of the Example. The unused heat is carried out of the regeneration tower with the desorbed carbon dioxide. The heat consumption for desorbing carbon dioxide is 2.80 GJ per ton of carbon dioxide.

[0085] In summary, by changing the position of the inlet of the CO2 absorbent when it enters the regeneration tower, and controlling the temperature and injection rate of the inlet, the absorbent enters from the upper middle part of the regeneration tower. This allows the absorbent to undergo sufficient regeneration and desorption in the regeneration tower, while also making full use of the regeneration heat of the regeneration tower. As a result, the heat energy consumption of carbon dioxide capture in flue gas using the amine method is significantly reduced, and the economic efficiency of carbon dioxide capture in flue gas is improved.

[0086] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A regeneration tower for capturing CO2 from flue gas, characterized in that, The regeneration tower includes a first inlet and a second inlet; The first feed inlet is located at the top of the regeneration tower; The second feed inlet is located below the first feed inlet, and the number of trays between the first feed inlet and the second feed inlet accounts for 20%-55% of the total number of trays.

2. The regeneration tower according to claim 1, wherein, The number of trays between the first feed inlet and the second feed inlet accounts for 30%-40% of the total number of trays.

3. The regeneration tower according to claim 1, wherein, The regeneration tower has 10-40 trays.

4. The regeneration tower according to claim 1, wherein, The first feed inlet and the second feed inlet are respectively equipped with temperature controllers, so that the temperature of the first feed inlet is 90-110℃ and the temperature of the second feed inlet is 90-110℃.

5. The regeneration tower according to claim 4, wherein, The temperature of the first feed inlet and the second feed inlet is 95-105℃.

6. The regeneration tower according to any one of claims 1-5, wherein, The first and second feed inlets are each equipped with a metering device, such that the volume ratio of the feed amount from the second feed inlet to the feed amount from the first feed inlet is 2-6:

1.

7. The regeneration tower according to claim 6, wherein, The first and second feed inlets are each equipped with a metering device, such that the volume ratio of the feed amount from the second feed inlet to the feed amount from the first feed inlet is 3-4:

1.

8. A method for regenerating CO2 captured from flue gas, characterized in that, The method includes regenerating and desorbing the pretreated CO2-rich absorbent in a regeneration tower as described in any one of claims 1-7.

9. The method according to claim 8, wherein, The pretreatment conditions include: temperature 95-105℃ and pressure 20-70kPa.

10. The method according to claim 8, wherein, The regeneration desorption temperature is 105-115℃.

11. The method according to claim 9 or 10, wherein, The absorbent contained in the absorbent solution is selected from C2-C6 alcoholamines and / or C2-C6 polyamines.

12. The method according to claim 11, wherein, The absorbent is selected from at least one of ethanolamine, methylmonoethanolamine, methyldiethanolamine, isopropanolamine, and diethylenetriamine.

13. A system for capturing CO2 from flue gas, characterized in that, The system includes an absorption tower and a regeneration tower as described in any one of claims 1-7.

14. The system according to claim 13, wherein, The system also includes a cooler, a rich solution pump, a lean solution pump, and a heat exchanger.

15. The system according to claim 14, wherein, The rich solution pump is connected to the bottom of the absorption tower and the top of the regeneration tower, respectively; the lean solution pump is connected to the top of the absorption tower and the bottom of the regeneration tower, respectively.

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