Regeneration tower and regeneration method for capturing CO2 in flue gas and system for capturing CO2 in flue gas

Abstract

The invention relates to the technical field of flue gas purification, and discloses a regeneration tower and a regeneration method for capturing CO2 in flue gas and a system for capturing CO2 in flue gas, the regeneration tower comprises a first feed inlet and a second feed inlet; the first feeding hole is formed in the top of the regeneration tower; the second feed port is located below the first feed port, and the number of the tower plates between the first feed port and the second feed port accounts for 20%-55% of the total number of the tower plates. The regeneration method for capturing the CO2 in the flue gas comprises the step of carrying out regeneration desorption treatment on the pretreated CO2 absorption liquid in the regeneration tower, and the method can obviously reduce the heat energy consumption of the carbon dioxide in the flue gas captured by the alcohol amine method, so that the economic benefit of capturing the carbon dioxide in the flue gas is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of exhaust gas purification in industries such as petrochemical industry, electric power, steel, cement, etc., and specifically to a method for capturing CO in flue gas. 2 Regeneration tower and regeneration method and CO capture in flue gas 2 system. Background Art

[0002] As global temperatures continue to rise, it poses a great threat to human society and the earth's natural environment. Carbon emissions are an important cause of the continued rise in global temperatures. China's carbon emissions rank first in the world, and its emission intensity is high. The carbon emission structure is directly related to traditional resource endowments. Coal-fired power plants, steel and cement emissions account for more than 60% of the national total.

[0003] Large-scale carbon dioxide capture has become an urgent need for key tasks in key industries or fields such as electricity, cement, steel, and petrochemicals. Carbon dioxide capture, utilization and storage (CCUS) has become a hot topic, among which carbon dioxide capture from flue gas is the most critical link.

[0004] At present, the most mature flue gas capture carbon dioxide technology developed at home and abroad is the amine method technology, which has been successfully implemented on an industrial scale, but the operating cost is relatively high, mainly due to the high heat consumption of carbon dioxide regeneration.

[0005] The process flow of the alcohol amine capture technology mainly includes: 1. Flue gas enters the absorption tower, and the carbon dioxide in the flue gas is absorbed by the alcohol amine solution at 40°C; 2. The alcohol amine solution after absorbing carbon dioxide enters the regeneration tower, and desorbs carbon dioxide at 110°C; 3. The alcohol amine solution forms a cycle in the absorption tower and the regeneration tower. However, in order to make the desorption and regeneration temperature of the solution reach 110°C, heat must be provided to the regeneration tower, which is the main heat consumption for capturing carbon dioxide from flue gas. At present, without other external energy-saving measures, the heat consumption for capturing 1 ton of carbon dioxide is 2.8GJ, which is very high, and the efficiency and economy of capturing carbon dioxide are low.

[0006] To this end, reducing the heat consumption of capturing carbon dioxide and improving economic efficiency have become the focus of research and development at this stage. Summary of the invention

[0007] The purpose of the present invention is to overcome the problems of low regeneration efficiency and high heat consumption of carbon dioxide in flue gas in the prior art, and to provide a method for capturing CO in flue gas. 2 Regeneration tower and regeneration method and CO capture in flue gas 2The method can significantly reduce the thermal energy consumption of capturing carbon dioxide in flue gas by the alcohol amine method, thereby improving the economic benefits of capturing carbon dioxide in flue gas.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for capturing CO in flue gas. 2 A regeneration tower, wherein the regeneration tower comprises a first feed inlet and a second feed inlet;

[0009] Wherein, 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 plates between the first feed inlet and the second feed inlet accounts for 20%-55% of the total number of plates.

[0011] The second aspect of the present invention provides a method for capturing CO in flue gas. 2 A regeneration method, wherein the method comprises: 2 The absorbed rich liquid is subjected to regeneration and desorption treatment in the regeneration tower described in the first aspect of the present invention.

[0012] The third aspect of the present invention provides a method for capturing CO in flue gas. 2 A system, wherein the system comprises an absorption tower and the regeneration tower described in the first aspect of the present invention.

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

[0014] The present invention increases the CO 2 The absorption rich liquid enters the second feed inlet of the regeneration tower and its position is limited, and the temperature and injection volume of the second feed inlet are controlled so that the absorption rich liquid enters from the upper middle part of the regeneration tower. This can not only allow the absorption rich liquid to be fully regenerated and desorbed in the regeneration tower, but also make full use of the regeneration heat of the regeneration tower, thereby significantly reducing the thermal energy consumption of capturing carbon dioxide from flue gas by the alcohol amine method, improving the regeneration efficiency, and improving the economic benefits of capturing carbon dioxide from flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is CO 2 Structural diagram of the regeneration tower.

[0016] Figure 2 Flue gas capture CO 2 Solution regeneration device.

[0017] Description of Reference Numerals

[0018] 1 Absorption tower 2 Cooler 3 Rich liquid pump

[0019] 4 heat exchanger 5 lean liquid pump 6 regeneration tower DETAILED DESCRIPTION

[0020] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0021] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for capturing CO in flue gas. 2 A regeneration tower, the regeneration tower comprising a first feed inlet and a second feed inlet;

[0022] Wherein, 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 plates between the first feed inlet and the second feed inlet accounts for 20%-55% of the total number of plates.

[0024] In the present invention, there is no particular limitation on the volume of the regeneration tower, and the volume of the regeneration tower can be increased or decreased accordingly according to actual production needs. In order to clearly describe the positions of the first feed inlet and the second feed inlet on the regeneration tower, those skilled in the art usually describe the positions of the feed inlets by the positions of the trays in the regeneration tower. Figure 1 As shown, feed port No. 1 is the top of the regeneration tower and is the location of the first feed port; feed ports No. 2 to No. 8 are located below feed port No. 1, and any one of them can be the location of the second feed port.

[0025] In the present invention, the inventors found that adding a second feed port for the rich liquid to enter the regeneration tower can reduce the CO in the flue gas captured by the alcohol amine method. 2 Specifically, the inventors found that with staged feeding, the CO 2 When the rich liquid is absorbed and enters the regeneration tower from the first feed inlet and the second feed inlet, the CO at the lower end of the regeneration tower can be 2 The regeneration and desorption process of the absorbent in the regeneration tower is more thorough. At the same time, the excess heat is also used to desorb the CO at the top of the regeneration tower. 2 The absorption liquid makes full use of the heat in the system. Under the premise of providing the same heat source, more carbon dioxide can be desorbed, thereby reducing the CO2 capture rate of flue gas. 2 heat consumption, improving economic benefits; as the position of the second feed inlet gradually moves downward, for example, from the second feed inlet to the sixth feed inlet, the CO at the lower end of the regeneration tower 2 The absorption liquid is regenerated and desorbed more thoroughly in the regeneration tower, and the excess heat desorbs the upper absorption liquid, allowing more CO to be desorbed.2 , the heat consumption is further reduced; and as the position of the second feed port moves further downward, for example, the position of the second feed port moves downward from the sixth feed port to the seventh or eighth feed ports, resulting in CO 2 The residence time of the absorption liquid in the regeneration tower is too short, the heat exchange and regeneration desorption are insufficient, and the amount of carbon dioxide desorbed by regeneration decreases, resulting in a rebound in the heat consumption per ton of carbon dioxide. Preferably, the second feed port is located at feed port No. 4 or No. 5.

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

[0027] In the present invention, the number of plates of the regeneration tower can be designed to meet the regeneration requirements. Preferably, the number of plates of the regeneration tower is 10-40.

[0028] In the present invention, when the first feed port and the second feed port meet the above range, the absorbed rich 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 thermal energy consumption of capturing carbon dioxide from flue gas by the amine method, improving the regeneration efficiency, and improving the economic benefits of capturing carbon dioxide from flue gas.

[0029] In the present invention, in order to further improve CO 2 The absorption liquid is regenerated and desorbed in the regeneration tower to increase the CO 2 In order to control the flow rate, it is necessary to limit the temperature and injection volume of the feed port.

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

[0031] Preferably, the temperature of the first feed port and the second feed port is 95-105°C.

[0032] According to some embodiments of the present invention, the first feed port and the second feed port are respectively provided with a meter, 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, and 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 the present invention, when the temperature and injection volume of the feed port meet the above conditions, CO 2 The absorption liquid is fully regenerated and desorbed in the regeneration tower.

[0034] In the present invention, the temperature at the bottom of the regeneration tower has an influence on the CO2 The amount has an impact.

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

[0036] A second aspect of the present invention provides a flue gas capture CO 2 A regeneration method comprising: 2 The absorbed rich liquid is subjected to regeneration and desorption treatment in the regeneration tower described in the first aspect of the present invention.

[0037] In the present invention, the flue gas refers to the gas generated by industries such as petrochemical, electric power, steel, cement, etc. Based on the total volume of the flue gas, the flue gas contains 8 vol%-16 vol% CO 2 , 4vol%-10vol% O 2 , 70vol%-88vol% N 2 .

[0038] In the present invention, the pretreatment method comprises: passing the flue gas into a 2 The absorption tower of the absorption liquid absorbs the CO in the flue gas. 2 Absorb to obtain CO 2 Absorb the rich liquid.

[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 absorption liquid is selected from C 2 -C 6 of ethanolamine and / or C 2 -C 6 Preferably, the absorption liquid is selected from at least one of ethanolamine, methyl monoethanolamine, methyl diethanolamine, isopropanolamine and diethylenetriamine.

[0041] In the present invention, if Figure 2 As shown. CO at the bottom of absorption tower 1 2 The absorption liquid enters from the No. 1 feed port and No. 2-8 feed ports at the top of the regeneration tower 6 through the rich liquid pump 3, flows from the top of the regeneration tower 6 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 absorption liquid are converted into gas, regenerated and desorbed from the regeneration tower 6, and discharged from the top of the regeneration tower 6; the regenerated absorption liquid is discharged from the bottom of the regeneration tower 6, thereby completing the CO 2 Regeneration and desorption process of absorption liquid.

[0042] The third aspect of the present invention provides a method for capturing CO in flue gas. 2A regeneration system comprising an absorption tower 1 and the regeneration tower 6 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] Preferably, 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 capturing CO in flue gas. 2 Regeneration method. Figure 2 The regeneration device shown in the figure is used, and the specific operation method includes:

[0046] The heat source provided at the bottom of the regeneration tower 6 is 2800 kJ / h. The absorption liquid from the absorption tower 1 after absorbing carbon dioxide through the heat exchanger 4 enters from the No. 1 feed port and No. 4 to No. 6 feed ports on the regeneration tower 6 (such as Figure 1 ), the feed temperature of feed inlet No. 1 is 95-105°C, the feed temperature of feed inlets No. 4 to No. 6 is 95-105°C, the volume ratio of the feed amount of the second feed inlet to the feed amount of the first feed inlet is 3-4:1, the absorption liquid after regeneration and desorption from the regeneration tower 6 flows out from the bottom of the regeneration tower 6, enters the top of the absorption tower 1 through the lean liquid pump 5, and is recycled, and the temperature at the bottom of the regeneration tower 6 is 105-115°C. The flow rate of carbon dioxide at the top outlet of the regeneration tower 6 is measured respectively, and the heat consumption per ton of carbon dioxide is calculated.

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

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

[0049]

[0050] The raw materials in this example are all commercially available products.

[0051] Example 1

[0052] The present invention provides a method for capturing CO in flue gas. 2 Regeneration method. Figure 2 The regeneration device shown in the figure is used, the number of regeneration tower plates is 20, and the specific operation method includes:

[0053] The heat source provided at the bottom of the regeneration tower 6 is 2800 kJ / h. The absorption liquid from the absorption tower 1 after absorbing carbon dioxide through the heat exchanger 4 enters from the No. 1 feed port and the No. 2 feed port on the regeneration tower 6 respectively (such as Figure 1), the number of plates at the No. 2 feed port accounts for 20% of the total number of plates, the feed temperature at the No. 1 feed port is 98°C, the feed rate is 5L / h, the feed temperature at the No. 2 feed port is 98°C, the feed rate is 15L / h, and the flow rate of carbon dioxide at the top outlet of the regeneration tower 6 is measured to be 0.56m 3 / h, the absorption liquid after regeneration and desorption from the regeneration tower 6 flows out from the bottom of the regeneration tower 6, enters the top of the absorption tower 1 through the lean liquid pump 5, and is recycled. The temperature at the bottom of the regeneration tower 6 is 110°C. The heat consumption per ton of carbon dioxide is calculated to be 2.59GJ.

[0054] Example 2

[0055] The present invention provides a method for capturing CO in flue gas. 2 Regeneration method. Figure 2 The regeneration device shown in the figure is used, the number of regeneration tower plates is 20, and the specific operation method includes:

[0056] The heat source provided at the bottom of the regeneration tower 6 is 2800 kJ / h. The absorption liquid from the absorption tower 1 after absorbing carbon dioxide through the heat exchanger 4 enters from the No. 1 feed port and the No. 3 feed port on the regeneration tower 6 respectively (such as Figure 1 ), the number of plates at feed port No. 3 accounts for 25% of the total number of plates, the feed temperature at feed port No. 1 is 98°C, the feed rate is 5L / h, the feed temperature at feed port No. 3 is 98°C, the feed rate is 15L / h, and the flow rate of carbon dioxide at the top outlet of regeneration tower 6 is measured to be 0.56m 3 / h, the absorption liquid after regeneration and desorption from the regeneration tower 6 flows out from the bottom of the regeneration tower 6, enters the top of the absorption tower 1 through the lean liquid pump 5, and is recycled. The temperature at the bottom of the regeneration tower 6 is 110°C. The heat consumption per ton of carbon dioxide is calculated to be 2.40GJ.

[0057] Example 3

[0058] The present invention provides a method for capturing CO in flue gas. 2 Regeneration method. Figure 2 The regeneration device shown in the figure is used, the number of regeneration tower plates is 20, and the specific operation method includes:

[0059] The heat source provided at the bottom of the regeneration tower 6 is 2800 kJ / h. The absorption liquid from the absorption tower 1 after absorbing carbon dioxide through the heat exchanger 4 enters from the No. 1 feed port and the No. 4 feed port on the regeneration tower 6 respectively (such as Figure 1 ), the number of plates at the No. 4 feed port accounts for 30% of the total number of plates, the feed temperature at the No. 1 feed port is 98°C, the feed rate is 5L / h, the feed temperature at the No. 4 feed port is 98°C, the feed rate is 15L / h, and the flow rate of carbon dioxide at the top outlet of the regeneration tower 6 is measured to be 0.65m 3 / h, the absorption liquid after regeneration and desorption from the regeneration tower 6 flows out from the bottom of the regeneration tower 6, enters the top of the absorption tower 1 through the lean liquid pump 5, and is recycled. The temperature at the bottom of the regeneration tower 6 is 110°C. The heat consumption per ton of carbon dioxide is calculated to be 2.15GJ.

[0060] Example 4

[0061] The present invention provides a method for capturing CO in flue gas. 2 Regeneration method. Figure 2 The regeneration device shown in the figure is used, the number of regeneration tower plates is 20, and the specific operation method includes:

[0062] The heat source provided at the bottom of the regeneration tower 6 is 2800 kJ / h, and the absorption liquid from the absorption tower 1 after absorbing carbon dioxide through the heat exchanger 4 enters from the No. 1 feed port and the No. 5 feed port on the regeneration tower 6 respectively (such as Figure 1 ), the number of plates at the No. 5 feed port accounts for 40% of the total number of plates, the feed temperature at the No. 1 feed port is 98°C, the feed rate is 5L / h, the feed temperature at the No. 5 feed port is 98°C, the feed rate is 15L / h, and the flow rate of carbon dioxide at the top outlet of the regeneration tower 6 is measured to be 0.65m 3 / h, the absorption liquid after regeneration and desorption from the regeneration tower 6 flows out from the bottom of the regeneration tower 6, enters the top of the absorption tower 1 through the lean liquid pump 5, and is recycled. The temperature at the bottom of the regeneration tower 6 is 110°C. The heat consumption per ton of carbon dioxide is calculated to be 2.15GJ.

[0063] Example 5

[0064] The present invention provides a method for capturing CO in flue gas. 2 Regeneration method. Figure 2 The regeneration device shown in the figure is used, the number of regeneration tower plates is 20, and the specific operation method includes:

[0065] The heat source provided at the bottom of the regeneration tower 6 is 2800 kJ / h. The absorption liquid from the absorption tower 1 after absorbing carbon dioxide through the heat exchanger 4 enters from the No. 1 feed port and the No. 6 feed port on the regeneration tower 6 respectively (such as Figure 1 ), the number of plates at feed port 6 accounts for 45% of the total number of plates, the feed temperature at feed port 1 is 98°C, the feed rate is 5L / h, the feed temperature at feed port 6 is 98°C, the feed rate is 15L / h, and the flow rate of carbon dioxide at the top outlet of regeneration tower 6 is measured to be 0.60m 3 / h, the absorption liquid after regeneration and desorption from the regeneration tower 6 flows out from the bottom of the regeneration tower 6, enters the top of the absorption tower 1 through the lean liquid pump 5, and is recycled. The temperature at the bottom of the regeneration tower 6 is 110°C. The heat consumption per ton of carbon dioxide is calculated to be 2.33GJ.

[0066] Example 6

[0067] The present invention provides a method for capturing CO in flue gas. 2Regeneration method. Figure 2 The regeneration device shown in the figure is used, the number of regeneration tower plates is 20, and the specific operation method includes:

[0068] The heat source provided at the bottom of the regeneration tower 6 is 2800 kJ / h. The absorption liquid from the absorption tower 1 after absorbing carbon dioxide through the heat exchanger 4 enters from the No. 1 feed port and the No. 7 feed port on the regeneration tower 6 respectively (such as Figure 1 ), the number of plates at feed port No. 7 accounts for 50% of the total number of plates, the feed temperature at feed port No. 1 is 98°C, the feed rate is 5L / h, the feed temperature at feed port No. 7 is 98°C, the feed rate is 15L / h, and the flow rate of carbon dioxide at the top outlet of regeneration tower 6 is measured to be 0.56m 3 / h, the absorption liquid after regeneration and desorption from the regeneration tower 6 flows out from the bottom of the regeneration tower 6, enters the top of the absorption tower 1 through the lean liquid pump 5, and is recycled. The temperature at the bottom of the regeneration tower 6 is 110°C. The heat consumption per ton of carbon dioxide is calculated to be 2.50GJ.

[0069] Example 7

[0070] The present invention provides a method for capturing CO in flue gas. 2 Regeneration method. Figure 2 The regeneration device shown in the figure is used, and the specific operation method includes:

[0071] The heat source provided at the bottom of the regeneration tower 6 is 2800 kJ / h. The absorption liquid from the absorption tower 1 after absorbing carbon dioxide through the heat exchanger 4 enters from the No. 1 feed port and the No. 8 feed port on the regeneration tower 6 respectively (such as Figure 1 ), the number of plates at feed port No. 8 accounts for 55% of the total number of plates, the feed temperature at feed port No. 1 is 98°C, the feed rate is 5L / h, the feed temperature at feed port No. 8 is 98°C, the feed rate is 15L / h, and the flow rate of carbon dioxide at the top outlet of regeneration tower 6 is measured to be 0.56m 3 / h, the absorption liquid after regeneration and desorption from the regeneration tower 6 flows out from the bottom of the regeneration tower 6, enters the top of the absorption tower 1 through the lean liquid pump 5, and is recycled. The temperature at the bottom of the regeneration tower 6 is 110°C. The heat consumption per ton of carbon dioxide is calculated to be 2.50GJ.

[0072] Example 8

[0073] The same method as in Example 1 is used, except that the absorption liquid from the absorption tower 1 after absorbing carbon dioxide through the heat exchanger 4 enters the regeneration tower 6 from the third feed port and the fourth feed port (such as Figure 1 ), the flow rate of carbon dioxide at the top outlet of regeneration tower 6 was measured to be 0.46m 3 / h, the heat consumption per ton of carbon dioxide is calculated to be 3.1GJ.

[0074] Example 9

[0075] The same method as in Example 1 was used, except that the feed rate at feed port No. 1 was 10 L / h, the feed rate at feed port No. 2 was 10 L / h, and the flow rate of carbon dioxide at the top outlet of regeneration tower 6 was measured to be 0.32 m 3 / h, the heat consumption per ton of carbon dioxide is calculated to be 4.5GJ.

[0076] Example 10

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

[0078] Comparative Example 1

[0079] Provide a conventional method for capturing CO in flue gas 2 The specific operation methods include:

[0080] The heat source provided by the bottom of regeneration tower 6 is 2800 kJ / h. The absorption liquid from absorption tower 1 after absorbing carbon dioxide through heat exchanger 4 enters from feed port 1 on regeneration tower 6. The temperature of the feed port is 98°C, the feed rate is 20 L / h, and the flow rate of carbon dioxide at the top outlet of regeneration tower 6 is measured to be 0.5 m 3 / h, the absorption liquid after regeneration and desorption from the regeneration tower 6 flows out from the bottom of the regeneration tower 6, enters the top of the absorption tower 1 through the lean liquid pump 5, and is recycled. The temperature at the bottom of the regeneration tower 6 is 110°C. The heat consumption per ton of carbon dioxide is calculated to be 2.80GJ.

[0081] It can be seen from Examples 1-7 and Comparative Example 1 that with the staged feeding, the position of the first feed port is relatively fixed, and the position of the second feed port moves downward, so that the CO at the lower end 2 The regeneration and desorption process of the absorbent in the regeneration tower is more thorough. At the same time, the excess heat desorbs the CO at the top of the regeneration tower. 2 The absorption liquid allows more carbon dioxide to be desorbed. It can be seen from Examples 1 and 2 that as the position of the second feed port moves downward, the heat consumption per ton of carbon dioxide decreases, which are 2.59 GJ and 2.40 GJ respectively. Compared with Comparative Example 1 (traditional desorption method), the heat consumption for desorbing one ton of carbon dioxide decreases by 7.5% and 14.29% respectively. It can be seen from Examples 3-4 that as the position of the second feed port continues to move downward, the heat consumption per ton of carbon dioxide decreases to the minimum, which is 2.15 GJ. Compared with Comparative Example 1 (traditional desorption method), the heat consumption for desorbing one ton of carbon dioxide decreases by 23.21%.

[0082] It can be seen from Examples 5-7 that as the position of the second feed port continues to move downward, CO 2The residence time of the absorption liquid in the regeneration tower is too short, the heat exchange and regeneration desorption are insufficient, and the amount of carbon dioxide desorbed by regeneration decreases again, resulting in a rebound in the heat consumption per ton of carbon dioxide (compared with Examples 3-4), which are 2.33GJ, 2.50GJ, and 2.50GJ, respectively. However, compared with Comparative Example 1 (traditional desorption method), the heat consumption of desorbing one ton of carbon dioxide in Examples 5-7 decreases by 16.79%, 10.14%, and 10.14%, respectively. Therefore, the solution must be placed in a suitable position when entering the regeneration tower to obtain the minimum regeneration heat consumption and improve economic benefits.

[0083] It can be seen from Example 8 that as the positions of the first and second feed ports move downward, CO 2 The residence time of the absorption liquid in the regeneration tower is too short, the heat exchange and regeneration desorption are insufficient, and the amount of carbon dioxide desorbed by regeneration continues to decrease, resulting in a continued increase in the heat consumption per ton of carbon dioxide (3.1 GJ). It can be seen from Examples 9-10 that changing the temperature and feed amount of the first feed port and the second feed port, respectively, results in a continued increase in the heat consumption per ton of carbon dioxide, which are 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 embodiment, and the unused heat is taken out of the regeneration tower along with the desorbed carbon dioxide. The heat consumption of desorbing carbon dioxide is: 2.80 GJ per ton of carbon dioxide.

[0085] In summary, the method of the present invention is adopted to change CO 2 The position of the feed port when the absorption liquid enters the regeneration tower, and the temperature and injection volume of the feed port are controlled so that the absorption liquid enters from the upper middle part of the regeneration tower, so that the absorption 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 thermal energy consumption of capturing carbon dioxide from flue gas by the alcohol amine method and improving the economic benefits of capturing carbon dioxide from flue gas.

[0086] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A regeneration tower for capturing CO2 in flue gas, characterized in that: The regeneration tower comprises a first feed inlet and a second feed inlet; Wherein, 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 plates between the first feed inlet and the second feed inlet accounts for 20%-55% of the total number of plates.

2. The regeneration tower according to claim 1, wherein: The number of plates between the first feed inlet and the second feed inlet accounts for 30%-40% of the total number of plates; preferably, the number of plates of the regeneration tower is 10-40.

3. The regeneration tower according to claim 1 or 2, wherein: The first feed port and the second feed port are respectively provided with temperature controllers, so that the temperature of the first feed port is 90-110° C., and the temperature of the second feed port is 90-110° C.; Preferably, the temperature of the first feed port and the second feed port is 95-105°C.

4. The regeneration tower according to any one of claims 1 to 3, wherein: The first feed port and the second feed port are respectively provided with metering devices, so that 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 3-4:

1.

5. A regeneration method for capturing CO2 in flue gas, characterized in that: The method comprises subjecting the pretreated CO2 absorption rich liquid to regeneration and desorption treatment in a regeneration tower as described in any one of claims 1 to 4.

6. The method according to claim 5, wherein: The pretreatment conditions include: temperature 95-105° C., pressure 20-70 kPa.

7. The method according to any one of claims 1 to 6, wherein: The regeneration desorption temperature is 105-115°C.

8. The method according to claim 6 or 7, wherein: The absorbent contained in the absorption rich liquid is selected from C2-C6 alcohol amines and / or C2-C6 polyamines; Preferably, the absorbent is selected from at least one of ethanolamine, methylmonoethanolamine, methyldiethanolamine, isopropanolamine and diethylenetriamine.

9. A system for capturing CO2 in flue gas, characterized in that: The system comprises an absorption tower and a regeneration tower as claimed in any one of claims 1 to 4.

10. The system according to claim 9, wherein: The system also includes a cooler, a rich liquid pump, a lean liquid pump and a heat exchanger; Preferably, the rich liquid pump is connected to the bottom of the absorption tower and the top of the regeneration tower respectively; the lean liquid pump is connected to the top of the absorption tower and the bottom of the regeneration tower respectively.

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