A carbon dioxide capture system and method

Abstract

The application discloses a carbon dioxide capturing system and method, which comprises an absorption tower, a regeneration tower, a heater and a catalytic desorption reactor. The bottom of the absorption tower is provided with a rich liquid outlet, the top of the regeneration tower is provided with a rich liquid inlet, and the rich liquid outlet and the rich liquid inlet are communicated. The bottom of the regeneration tower is provided with a semi-lean liquid outlet, the catalytic desorption reactor is provided with a semi-lean liquid inlet, and the semi-lean liquid outlet and the semi-lean liquid inlet are communicated. The catalytic desorption reactor is further provided with a lean liquid outlet, the top of the absorption tower is provided with a lean liquid inlet, and the lean liquid outlet and the lean liquid inlet are communicated. The heater is provided with a steam outlet, the regeneration tower is provided with a steam inlet, and the steam outlet and the steam inlet are communicated. The catalytic desorption reactor is arranged to utilize the steam condensate discharged from the regeneration tower again, and the steam condensate provides the required heat for the catalytic desorption reactor, so that an external heat source is not needed, and the comprehensive energy consumption of the carbon dioxide capturing system is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas treatment, more particularly to a carbon dioxide capture system and method. BACKGROUND

[0002] Currently, carbon dioxide in flue gas is captured by using an organic amine solution to absorb carbon dioxide in flue gas, to generate amine carbamate, and to change the absorption solution into rich solution, which is discharged from the bottom of the absorption tower, enters a desorption tower after heat exchange, and realizes desorption of carbon dioxide in the rich solution and regeneration of the absorbent under certain temperature and pressure conditions, to obtain lean solution. The lean solution returns to the absorption tower after heat exchange to continue to absorb carbon dioxide in flue gas, to complete the cycle of the organic amine solution. In the process of capturing carbon dioxide in flue gas, the energy consumption of the absorbent regeneration is composed of the sensible heat of the absorption solution, the reaction heat of the absorbent, and the latent heat of water vaporization in the regeneration gas, which accounts for more than 60% of the overall energy consumption of the entire process, that is, the energy consumption of the absorbent regeneration is high.

[0003] Therefore, it is urgent to provide a carbon dioxide capture system and method capable of reducing the energy consumption of absorbent regeneration. SUMMARY

[0004] The present application aims to overcome the above-mentioned defects in the prior art, and to provide a carbon dioxide capture system and method.

[0005] To achieve the above-mentioned purpose, the technical solution of the present application is as follows:

[0006] A carbon dioxide capture system, comprising: an absorption tower, a regeneration tower, a heater, and a catalytic desorption reactor;

[0007] The bottom of the absorption tower is provided with a first rich solution outlet, the top of the regeneration tower is provided with a first rich solution inlet, and the first rich solution outlet and the first rich solution inlet are in communication;

[0008] The bottom of the regeneration tower is provided with a semi-lean solution outlet, the catalytic desorption reactor is provided with a semi-lean solution inlet, and the semi-lean solution outlet and the semi-lean solution inlet are in communication;

[0009] The catalytic desorption reactor is further provided with a lean solution outlet, the top of the absorption tower is provided with a lean solution inlet, and the lean solution outlet and the lean solution inlet are in communication;

[0010] The heater is provided with a second rich solution inlet and a third rich solution outlet, the regeneration tower is further provided with a second rich solution outlet and a third rich solution inlet, the second rich solution inlet and the second rich solution outlet are in communication, and the third rich solution outlet and the third rich solution inlet are in communication;

[0011] The heater is provided with a steam inlet and a first steam condensate outlet, and the catalytic desorption reactor is provided with a steam condensate inlet and a second steam condensate outlet, and the first steam condensate outlet and the steam condensate inlet are communicated.

[0012] Optionally, the catalytic desorption reactor is filled with a catalyst.

[0013] Optionally, the catalyst is a metal oxide catalyst, a molecular sieve catalyst, a solid superacid catalyst or a composite catalyst.

[0014] Optionally, the carbon dioxide capture system further comprises a heat exchanger, the heat exchanger comprising a first channel and a second channel; two ends of the first channel are respectively communicated with the first rich liquid outlet and the first rich liquid inlet, and two ends of the second channel are respectively communicated with the lean liquid outlet and the lean liquid inlet.

[0015] Optionally, the carbon dioxide capture system further comprises a cooling assembly, the cooling assembly connecting the lean liquid inlet and the second channel.

[0016] Optionally, the bottom of the absorption tower is provided with a flue gas inlet, and the flue gas inlet is communicated with a flue gas source.

[0017] Optionally, the absorption tower is filled with an organic amine solution.

[0018] Optionally, the top of the absorption tower is provided with a purified gas outlet.

[0019] Optionally, the top of the regeneration tower is provided with a first regenerated gas outlet, and the top of the catalytic desorption reactor is provided with a second regenerated gas outlet.

[0020] A carbon dioxide capture method applied to the carbon dioxide capture system described above, comprising:

[0021] The flue gas enters the absorption tower and contacts with the organic amine solution in the absorption tower, and the carbon dioxide in the flue gas is absorbed by the organic amine solution, and the rich liquid and the purified gas are obtained respectively;

[0022] The rich liquid enters the regeneration tower for preliminary desorption, and then enters the heater, steam is introduced into the heater, the rich liquid is heated and returned to the regeneration tower, and the desorbed rich liquid obtains the semi-lean liquid and the carbon dioxide gas, and the steam forms steam condensate after providing heat for the rich liquid;

[0023] The semi-lean liquid enters the catalytic desorption reactor, the steam condensate provides heat for the semi-lean liquid, and the semi-lean liquid catalytically desorbed obtains the lean liquid and the carbon dioxide gas;

[0024] The lean liquid enters the absorption tower.

[0025] The embodiment of the present application has the following beneficial effects:

[0026] The carbon dioxide capture system and method provided by the embodiment of the present application, wherein the carbon dioxide capture system comprises an absorption tower, a regeneration tower, a heater and a catalytic desorption reactor; the bottom of the absorption tower is provided with a rich liquid outlet, the top of the regeneration tower is provided with a rich liquid inlet, and the rich liquid outlet and the rich liquid inlet are communicated; the bottom of the regeneration tower is provided with a semi-lean liquid outlet, the catalytic desorption reactor is provided with a semi-lean liquid inlet, and the semi-lean liquid outlet and the semi-lean liquid inlet are communicated; the catalytic desorption reactor is further provided with a lean liquid outlet, and the top of the absorption tower is provided with a lean liquid inlet, and the lean liquid outlet and the lean liquid inlet are communicated; the heater is provided with a steam outlet, the regeneration tower is provided with a steam inlet, and the steam outlet and the steam inlet are communicated; by arranging the catalytic desorption reactor, the steam condensate discharged from the regeneration tower is reused, the steam condensate provides the required heat for the catalytic desorption reactor, and an external heat source is not needed, so that the comprehensive energy consumption of the carbon dioxide capture system is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0028] Among them:

[0029] Figure 1 is a schematic diagram of the carbon dioxide capture system provided by the present application.

[0030] Figure 2 is a flow chart of the carbon dioxide capture method provided by the present application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0032] With reference to Figure 1 , the present application discloses a carbon dioxide capture system, comprising: an absorption tower 1, a regeneration tower 2, a heater 3 and a catalytic desorption reactor 4;

[0033] The bottom of the absorption tower 1 is provided with a first rich liquid outlet 11, the top of the regeneration tower 2 is provided with a first rich liquid inlet 21, and the first rich liquid outlet 11 and the first rich liquid inlet 21 are communicated;

[0034] The bottom of the regeneration tower 2 is provided with a semi-lean liquid outlet 24, and the catalytic desorption reactor 4 is provided with a semi-lean liquid inlet 43, the semi-lean liquid outlet 24 is communicated with the semi-lean liquid inlet 43;

[0035] The bottom of the catalytic desorption reactor 4 is further provided with a lean liquid outlet 44, and the top of the absorption tower 1 is provided with a lean liquid inlet 12, the lean liquid outlet 44 is communicated with the lean liquid inlet 12;

[0036] The heater 3 is provided with a second rich liquid inlet 33 and a third rich liquid outlet 34, and the regeneration tower 2 is further provided with a second rich liquid outlet 22 and a third rich liquid inlet 23, the second rich liquid inlet 33 is communicated with the second rich liquid outlet 22, and the third rich liquid outlet 34 is communicated with the third rich liquid inlet 23;

[0037] The heater 3 is provided with a steam inlet 31 and a first steam condensate outlet 32, and the catalytic desorption reactor 4 is provided with a steam condensate inlet 41 and a second steam condensate outlet 42, the first steam condensate outlet 32 is communicated with the steam condensate inlet 41.

[0038] It should be noted that, with reference to Figure 2 , the carbon dioxide capture method of the carbon dioxide capture system in the embodiment comprises:

[0039] S1 The flue gas enters the absorption tower 1 and is in contact with the organic amine solution in the absorption tower 1, and the carbon dioxide in the flue gas is absorbed by the organic amine solution, and the rich liquid and the purified gas are obtained.

[0040] Specifically, the bottom of the absorption tower 1 in the embodiment is provided with a flue gas inlet 13, the flue gas inlet 13 is communicated with the flue gas source, and the flue gas is the flue gas discharged by the power, cement, steel, chemical and other industries, and the concentration of carbon dioxide in the flue gas is 5-40% (v); the top of the absorption tower 1 is provided with a liquid distributor, and the middle is provided with a tray or a packing; the bottom is provided with a gas distributor; the tray or the packing is arranged in the absorption tower to improve the gas-liquid mass transfer efficiency; the packing can adopt a scattered packing represented by a Pall ring, or other high-performance packings represented by a saddle packing, a ring saddle packing, a spherical packing, or a regular packing represented by a Stedman wire mesh and a Mellapak corrugated mesh.

[0041] The absorption tower 1 is filled with an organic amine solution, the organic amine solution absorbs the carbon dioxide in the flue gas in the absorption tower 1 to generate a carbamate salt, and the rich liquid is obtained; the carbon dioxide in the flue gas is absorbed by the organic amine solution to obtain the purified gas, and the top of the absorption tower 1 is provided with a purified gas outlet 14, and the purified gas (i.e. the purified flue gas) is discharged from the purified gas outlet 14. The organic amine solution can be one or more of a primary amine, a secondary amine, a tertiary amine, and a sterically hindered amine, and the solution concentration is 30-50% (wt).

[0042] S2 rich liquid into the regeneration tower 2 is preliminarily desorbed, and the rich liquid is fed into the heater 3 again, steam is introduced into the heater 3, and the heated rich liquid is returned to the regeneration tower 2, and the rich liquid is desorbed to obtain semi-lean liquid and carbon dioxide gas, and the steam provides heat for the rich liquid and forms steam condensate.

[0043] Specifically, in the embodiment, the regeneration tower 2 also adopts a packed tower, and the regeneration tower 2 is further provided with a liquid pool 26, the second rich liquid outlet 22 is communicated with the liquid pool 26, and the third rich liquid inlet 23 is arranged below the liquid pool 26. The rich liquid is introduced into the regeneration tower 2 from the first rich liquid inlet 21 at the top of the regeneration tower 2, flows into the liquid pool 26 at the bottom of the regeneration tower 2 after being packed, and then is heated in the heater 3, and the heated rich liquid is returned to the regeneration tower 2. The heated steam of the rich liquid provides heat for the rich liquid in the liquid pool 26, the rich liquid is further desorbed to obtain semi-lean liquid and carbon dioxide gas, the regeneration tower 2 is provided with a first regeneration gas outlet 25 at the top, the carbon dioxide gas and the evaporated water vapor rise and are discharged from the first regeneration gas outlet 25, and the carbon dioxide gas and the evaporated water vapor provide heat for the rich liquid in the packed tower of the regeneration tower 2 in the rising process. The pressure at the top of the regeneration tower 2 is 20-60 kPa (G), the temperature at the bottom of the regeneration tower 2 is 100-110 ℃, and the temperature at the top of the regeneration tower 2 is 70-90 ℃. In the embodiment, the heater 3 uses externally supplied steam as a regeneration heat source, and the heater is provided with a steam inlet 31 and a first steam condensate outlet 32, and the steam pressure is 0.3 MPa (G) or above.

[0044] S3 semi-lean liquid is introduced into the catalytic desorption reactor 4, the steam condensate provides heat for the semi-lean liquid, and the semi-lean liquid is catalytically desorbed to obtain lean liquid and carbon dioxide gas.

[0045] Specifically, the steam in the heater 3 provides heat for the rich liquid and forms steam condensate, the catalytic desorption reactor 4 is internally provided with a heat exchange device, the steam condensate is introduced into the catalytic desorption reactor 4 to provide the required heat for the further desorption of the semi-lean liquid, the semi-lean liquid is catalytically desorbed to obtain lean liquid and carbon dioxide gas, the catalytic desorption reactor 4 is provided with a second regeneration gas outlet 45 at the top, the carbon dioxide and the evaporated water vapor desorbed from the semi-lean liquid are discharged through the second regeneration gas outlet 45, the carbon dioxide capture system provided in the embodiment further comprises a carbon dioxide separator 7, the first regeneration gas outlet 25 and the second regeneration gas outlet 45 are both communicated with the carbon dioxide separator 7, the regeneration gas discharged from the catalytic desorption reactor 4 is mixed with the regeneration gas discharged from the regeneration tower 2 and is cooled, and then gaseous carbon dioxide product gas is obtained through gas-liquid separation of the carbon dioxide separator 7. The pressure in the catalytic desorption reactor 4 is 10-40 kPa (G), the temperature of the solution in the catalytic desorption reactor 4 is 90-100 ℃, and the temperature of the steam condensate is 100-115 ℃.

[0046] S4 lean liquid is introduced into the absorption tower 1. Specifically, the lean liquid after desorption equilibrium is cooled and then is fed into the absorption tower 1 to continue to absorb carbon dioxide, and the circulation of the absorption solution is completed.

[0047] Understandably, in this invention, flue gas enters the absorption tower 1 and contacts the organic amine solution, forming a rich liquid. The rich liquid is discharged from the first rich liquid outlet 11 and enters the regeneration tower 2 through the first rich liquid inlet 21 at the top of the regeneration tower 2. The rich liquid undergoes preliminary desorption in the regeneration tower 2 and is discharged through the second rich liquid outlet 22. The rich liquid enters the heater 3 through the second rich liquid inlet 33, while externally supplied steam enters the heater 3 through the steam inlet 31 to heat the rich liquid. The heated steam forms steam condensate, which is discharged from the first steam condensate outlet 32. The heated rich liquid exits from the third rich liquid outlet 3... 4. The gas is discharged and then returns to the regeneration tower through the third rich liquid inlet 23 of the regeneration tower 2. The gas rises and the liquid forms a semi-lean liquid. The semi-lean liquid is discharged through the semi-lean liquid outlet 24 at the bottom of the regeneration tower 2 and then enters the catalytic desorption reactor 4 through the semi-lean liquid inlet 43 at the top of the catalytic desorption reactor 4. At the same time, the steam condensate flows in from the steam condensate inlet 41 of the catalytic desorption reactor 4 to heat the semi-lean liquid. The heated steam condensate is discharged from the second steam condensate outlet 42. The semi-lean liquid is analyzed and balanced to obtain lean liquid. The lean liquid is discharged from the lean liquid outlet 44 and returns to the absorption tower 1 through the lean liquid inlet 12 at the top of the absorption tower 1.

[0048] The carbon dioxide capture system provided by the present invention reuses the steam condensate discharged from the heater 3 by setting up a catalytic desorption reactor 4. The steam condensate provides the heat required for desorption in the catalytic desorption reactor 4, eliminating the need for an external heat source and thus reducing the overall energy consumption of the carbon dioxide capture system.

[0049] In this embodiment, the catalytic desorption reactor 4 is filled with a catalyst.

[0050] Understandably, by placing a catalyst in the catalytic desorption reactor 4, the desorption temperature of the semi-lean liquor is lowered, thereby allowing the steam condensate discharged from the regeneration tower 2 to be reused, reducing the overall process energy consumption. Specifically, the catalyst is a metal oxide catalyst, a molecular sieve catalyst, a solid superacid catalyst, or a composite catalyst; the catalyst shape can be spherical, cylindrical, or other shapes.

[0051] In this embodiment, refer to Figure 1 The heat exchanger 5 includes a first channel 51 and a second channel 52; the two ends of the first channel 51 are connected to the first rich liquid outlet 11 and the first rich liquid inlet 21, respectively, and the two ends of the second channel 52 are connected to the lean liquid outlet 44 and the lean liquid inlet 12, respectively.

[0052] It is understandable that the rich solution is a low-temperature absorption solution, and the lean solution is an absorption solution after heating and desorption. By setting up heat exchanger 5, the rich solution and the lean solution exchange heat, so that the temperature of the low-temperature rich solution is initially raised and the temperature of the high-temperature lean solution is initially lowered, thereby reducing the energy consumption for subsequent reheating of the rich solution and cooling of the lean solution.

[0053] In the present embodiment, with reference to Figure 1 , the carbon dioxide capture system further comprises a cooling assembly 6, which is connected to the lean liquid inlet 12 and the second passage 52.

[0054] It can be understood that carbon dioxide gas in the absorption solution is easy to be precipitated at high temperature, i.e. the absorption rate of carbon dioxide in the absorption solution is reduced, therefore, the cooling assembly 6 is arranged, the lean liquid after heat exchange is cooled again and then enters the absorption tower 1 to continue absorbing carbon dioxide, thereby completing the circulation of the absorption solution. Specific embodiments:

[0056] Taking flue gas as raw gas, the carbon dioxide concentration is 11.9% (v), the oxygen content is 4.5% (v), the nitrogen content is 75% (v), and other components are water and trace amounts of sulfur dioxide and nitrogen oxides, and 30% (wt) of monoethanolamine aqueous solution is used as the absorption solution.

[0057] Comparative Example 1:

[0058] Comparative Example 1 is a process for capturing carbon dioxide in flue gas by an organic amine method in the prior art, comprising:

[0059] In the first step, flue gas enters from the lower part of the absorption tower, the absorption temperature is 40℃, the absorption pressure is 3kPa (G), the carbon dioxide capture rate in the flue gas is 91.4%, and the flue gas after absorption is discharged through the purified gas outlet at the top of the absorption tower, and the solution after absorbing carbon dioxide in the flue gas becomes rich liquid.

[0060] In the second step, the rich liquid is heated to a temperature of 80℃, enters the upper part of the regeneration tower, and desorbs carbon dioxide in the regeneration tower to obtain lean liquid. The tower top pressure is 30kPa, the tower bottom temperature is 108℃, the tower top temperature is 91℃, and the heating steam is 0.3MPa (G) saturated steam.

[0061] In the third step, the lean liquid at the bottom of the regeneration tower is sent into the absorption tower again after heat exchange and cooling to absorb carbon dioxide in the flue gas, thereby completing the circulation of the solution.

[0062] Example 1:

[0063] Example 1 is a process for capturing carbon dioxide in flue gas by an organic amine method provided by the present application, comprising:

[0064] In the first step, flue gas enters from the lower part of the absorption tower, the absorption temperature is 40℃, the absorption pressure is 3kPa (G), the carbon dioxide capture rate in the flue gas is 90.2%, and the flue gas after absorption is discharged through the purified gas outlet at the top of the absorption tower, and the solution after absorbing carbon dioxide in the flue gas becomes rich liquid.

[0065] The second step, the temperature of the rich solution is increased to 70°C after heat exchange, and the rich solution enters the upper part of the regeneration tower. The rich solution is desorbed of part of the carbon dioxide in the regeneration tower to obtain semi-lean solution. The tower top pressure is 25 kPa (G), the tower bottom temperature is 103°C, the tower top temperature is 82°C, the heating steam is 0.3 MPa (G) saturated steam, and 105°C steam condensate is obtained after heat exchange with the rich solution.

[0066] The third step, the steam condensate enters the heat exchanger at the bottom of the desorption reactor to provide heat for the desorption of the semi-lean solution.

[0067] The fourth step, the high-temperature semi-lean solution obtained in the second step enters the desorption reactor, and the carbon dioxide is further catalytically desorbed under the action of the solid acid catalyst. The desorbed carbon dioxide and the evaporated water vapor are discharged through the top outlet of the desorption reactor, mixed with the regeneration gas at the top of the regeneration tower, and then cooled and gas-liquid separated to obtain gaseous carbon dioxide product gas. The pressure in the catalytic desorption reactor is 20 kPa (G), and the temperature of the lean solution in the reactor is 95°C.

[0068] Example 2

[0069] Example 2 is an organic amine method for capturing carbon dioxide in flue gas provided by the carbon dioxide capture system of the present application, which comprises:

[0070] The first step, the flue gas enters from the lower part of the absorption tower, the absorption temperature is 40°C, the absorption pressure is 3 kPa (G), the carbon dioxide capture rate in the flue gas is 92.4%, and the flue gas after absorption is discharged through the purification gas outlet at the top of the absorption tower. The solution after absorbing the carbon dioxide in the flue gas becomes a rich solution.

[0071] The second step, the temperature of the rich solution is increased to 71°C after heat exchange, and the rich solution enters the upper part of the regeneration tower. The rich solution is desorbed of part of the carbon dioxide in the regeneration tower to obtain semi-lean solution. The tower top pressure is 30 kPa (G), the tower bottom temperature is 105°C, the tower top temperature is 86°C, the heating steam is 0.3 MPa (G) saturated steam, and 105°C steam condensate is obtained after heat exchange with the rich solution.

[0072] The third step, the steam condensate enters the heat exchanger at the bottom of the desorption reactor to provide heat for the desorption of the semi-lean solution.

[0073] The fourth step, the high-temperature semi-lean solution obtained in the second step enters the desorption reactor, and the carbon dioxide is further catalytically desorbed under the action of the solid acid catalyst. The desorbed carbon dioxide and the evaporated water vapor are discharged through the top outlet of the desorption reactor, mixed with the regeneration gas at the top of the regeneration tower, and then cooled and gas-liquid separated to obtain gaseous carbon dioxide product gas. The pressure in the catalytic desorption reactor is 20 kPa (G), and the temperature of the lean solution in the reactor is 95°C.

[0074] Example 3

[0075] Embodiment 3 is a process for capturing carbon dioxide in flue gas by an organic amine method provided by the carbon dioxide capture system of the present application, comprising:

[0076] In the first step, flue gas enters from the lower part of the absorption tower, the absorption temperature is 40℃, the absorption pressure is 3kPa(G), the carbon dioxide capture rate in the flue gas is 92.8%, and the flue gas after absorption is discharged through the purification gas outlet at the top of the absorption tower, and the solution after absorbing carbon dioxide in the flue gas becomes rich liquid.

[0077] In the second step, the rich liquid is heated to a temperature of 75℃, enters the upper part of the regeneration tower, and the rich liquid is desorbed in the regeneration tower to obtain semi-lean liquid. The tower top pressure is 30kPa(G), the tower bottom temperature is 106℃, the tower top temperature is 88℃, the heating steam is 0.3MPa(G) saturated steam, and after heat exchange with the rich liquid, 105℃ steam condensate is obtained.

[0078] In the third step, the steam condensate enters the heat exchanger at the bottom of the desorption reactor to provide heat for the desorption of the semi-lean liquid.

[0079] In the fourth step, the high-temperature semi-lean liquid obtained in the second step enters the desorption reactor, and under the action of the solid acid catalyst, further catalytic desorption of carbon dioxide is carried out. The desorbed carbon dioxide and the vaporized water vapor are discharged through the outlet at the top of the desorption reactor, mixed with the regenerated gas at the top of the regeneration tower, and after cooling and gas-liquid separation, gaseous carbon dioxide product gas is obtained. The pressure in the catalytic desorption reactor is 25kPa(G), and the temperature of the lean liquid in the reactor is 100℃.

[0080] Table 1 compares the amount of regeneration gas and energy consumption in Comparative Example 1 and Examples 1-3

[0081]

[0082] Referring to Table 1, compared with Comparative Example 1, the unit energy consumption for carbon dioxide desorption in Examples 1-3 of the present application is lower than that of the prior art, and the unit energy consumption for carbon dioxide desorption in the best embodiment 2 is more than 20% lower.

[0083] The above-described embodiments only express several embodiments of the present application, which are described in detail and specifically, but should not be understood as limiting the scope of the patent application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A carbon dioxide capture system, characterized by, The application relates to a carbon dioxide absorption and recovery system. The system comprises an absorption tower, a regeneration tower, a heater and a catalytic desorption reactor. The bottom of the absorption tower is provided with a first rich liquid outlet, the top of the regeneration tower is provided with a first rich liquid inlet, and the first rich liquid outlet is communicated with the first rich liquid inlet. The bottom of the regeneration tower is provided with a semi-lean liquid outlet, the catalytic desorption reactor is provided with a semi-lean liquid inlet, and the semi-lean liquid outlet is communicated with the semi-lean liquid inlet. The catalytic desorption reactor is further provided with a lean liquid outlet, the top of the absorption tower is provided with a lean liquid inlet, and the lean liquid outlet is communicated with the lean liquid inlet. The heater is provided with a second rich liquid inlet and a third rich liquid outlet, the regeneration tower is further provided with a second rich liquid outlet and a third rich liquid inlet, the second rich liquid inlet is communicated with the second rich liquid outlet, and the third rich liquid outlet is communicated with the third rich liquid inlet. The heater is used for heating the rich liquid from the regeneration tower and is provided with a steam inlet and a first steam condensate outlet; the regeneration tower is used for heat desorption of the rich liquid heated by the heater to obtain semi-lean liquid. The catalytic desorption reactor is filled with a catalyst and is used for catalytic desorption of the semi-lean liquid from the regeneration tower to obtain lean liquid. Furthermore, the first steam condensate outlet of the heater is communicated with the heat source inlet of the catalytic desorption reactor, so that the high-temperature steam condensate formed by condensation of steam in the heater is directly used as the only heat source of the catalytic desorption reactor to provide the required heat for the catalytic desorption process of the semi-lean liquid.

2. The carbon dioxide capture system of claim 1, wherein, The catalyst is a metal oxide catalyst, a molecular sieve catalyst, a solid superacid catalyst or a composite catalyst.

3. The carbon dioxide capture system of claim 1, wherein, The system further comprises a heat exchanger, the heat exchanger comprises a first channel and a second channel; the two ends of the first channel are respectively communicated with the first rich liquid outlet and the first rich liquid inlet, and the two ends of the second channel are respectively communicated with the lean liquid outlet and the lean liquid inlet.

4. The carbon dioxide capture system of claim 3, wherein, The system further comprises a cooling assembly, the cooling assembly is connected with the lean liquid inlet and the second channel.

5. The carbon dioxide capture system of claim 1, wherein, The bottom of the absorption tower is provided with a flue gas inlet, and the flue gas inlet is communicated with a flue gas source.

6. The carbon dioxide capture system of claim 1, wherein, The absorption tower is filled with an organic amine solution.

7. The carbon dioxide capture system of claim 1, wherein, The top of the absorption tower is provided with a purified gas outlet.

8. The carbon dioxide capture system of claim 1, wherein, The top of the regeneration tower is provided with a first regeneration gas outlet, and the top of the catalytic desorption reactor is provided with a second regeneration gas outlet.

9. A method for capturing carbon dioxide, applied to the carbon dioxide capturing system according to any one of claims 1-8, characterized in that, The application relates to a carbon dioxide absorption and recovery system. Flue gas enters the absorption tower and is contacted with the organic amine solution in the absorption tower, carbon dioxide in the flue gas is absorbed by the organic amine solution, and rich liquid and purified gas are obtained; The rich liquid enters the regeneration tower for preliminary desorption, the rich liquid further enters the heater, steam is introduced into the heater, the rich liquid is heated and returned to the regeneration tower, the rich liquid is desorbed to obtain semi-lean liquid and carbon dioxide gas, and the steam is condensed to form steam condensate after providing heat for the rich liquid; The semi-lean liquid enters the catalytic desorption reactor, the steam condensate provides heat for the semi-lean liquid, and the semi-lean liquid is catalytically desorbed to obtain lean liquid and carbon dioxide gas; The lean liquid enters the absorption tower.

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