CN115337756A

CN115337756A - Absorption device, carbon dioxide capture system, and carbon dioxide capture method

Info

Publication number: CN115337756A
Application number: CN202210985775.3A
Authority: CN
Inventors: 彭悦; 詹国雄; 陈阵; 司文哲; 李俊华
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2022-08-17
Filing date: 2022-08-17
Publication date: 2022-11-15
Anticipated expiration: 2042-08-17
Also published as: CN115337756B

Abstract

The invention provides an absorption device, a carbon dioxide capture system and a carbon dioxide capture method. The absorption device comprises: the device comprises a primary absorption tower, a secondary absorption tower and a flue gas pipeline, wherein a primary absorbent can be introduced into the primary absorption tower, a secondary absorbent can be introduced into the secondary absorption tower, and the flue gas pipeline is connected with the primary absorption tower and the secondary absorption tower; optionally, a circulating cooling assembly is connected inside and/or outside the secondary absorption tower, the primary absorbent and the secondary absorbent are the same or different, and in the primary absorption tower and the secondary absorption tower, the primary absorbent and the secondary absorbent absorb carbon dioxide in the flue gas and generate a rich amine solution or a split-phase rich amine solution; the circulating cooling assembly can cool the rich amine solution or the split-phase rich amine solution generated by the secondary absorption tower and then convey the cooled rich amine solution back to the secondary absorption tower. The absorption device and the carbon dioxide capture system can increase the gas-liquid retention time of the flue gas and the absorbent, and promote the capture efficiency of the absorption liquid on the carbon dioxide.

Description

Absorption device, carbon dioxide capture system, and carbon dioxide capture method

Technical Field

The invention relates to an absorption device, a carbon dioxide capture system and a carbon dioxide capture method, and belongs to the technical field of carbon dioxide capture.

Background

The carbon dioxide capturing and sealing technology is a key technology for realizing emission reduction of flue gas carbon dioxide generated by a coal/gas fired boiler at the present stage. According to different sequences of the carbon dioxide capturing units, the technology can be divided into technologies such as capturing before combustion, capturing after combustion, oxygen-enriched combustion and the like. The advantages of no modification of the original process, high inheritance degree of the original process and the like are adopted for trapping after combustion, so that the technology is widely applied in the process of decarbonizing the flue gas. According to the difference of the carbon dioxide capture action mechanism, the method can be divided into the following steps: chemical/physical absorption, physical adsorption, membrane separation, and the like. Among them, the chemical absorption method can achieve the purpose of capturing low-concentration carbon dioxide, and is widely applied to industrial flue gas decarburization.

The carbon capture by the chemical absorption method is the only technical path capable of capturing carbon dioxide on a large scale at the present stage, and the carbon capture system by the traditional absorption method has the limitations of high energy consumption, high amine consumption, high temperature and easy degradation and the like in industrial application, thereby greatly limiting the large-scale popularization and application of the carbon capture technology by the chemical absorption method, particularly the alcohol amine method.

The chemical absorption method based on an alcohol amine solution is currently the only carbon dioxide capture method to achieve commercial scale application, and monoethanolamine (MEA 20-30%) is considered as the first generation absorbent and is compared as a standard solvent. Although monoethanolamine has the advantages of high absorption rate, large absorption load, low volatility and the like, the energy consumption required for absorbing the regeneration of the rich amine solution is high, generally 3.7-4.0GJ/t carbon dioxide, and accounts for 58% -80% of the total capture energy consumption. Taking a 600MW coal fired power plant as an example, the use of typical monoethanolamine process absorption techniques will result in a net power generation efficiency drop from 41% to 28%. Therefore, a series of mixed amine absorption processes and phase-change absorption processes are developed at present, and a certain amount of sterically hindered amine (such as isobutanolamine and AMP) or tertiary amine (such as N, N-dimethylcyclohexylamine and DMCA) and the like are added to modulate the bonding strength of the monoethanolamine and the carbon dioxide, so that the desorption energy consumption and the desorption temperature are reduced, but the volatilization amount of the organic amine is increased.

Volatilization of organic amine is one of the main reasons for loss of effective components of the absorbent, and reduction of the volatilization amount of the organic amine can effectively control the carbon capture operation cost by an organic amine method. The existing absorption tower only utilizes a first-stage water washing cooler at the top of the tower to reduce the volatilization of organic amine, but has poor effect of condensing organic amine aiming at smoke with large air quantity and high humidity. In addition, along with the enhancement of human environmental awareness and the increasingly stricter national environmental standards, the volatility and toxicity of organic amine are more and more regarded. The organic amine gas further generates atmospheric chemical reaction when being volatilized into the atmosphere, generates carcinogens such as nitrosamine and the like, and further causes PM in the atmosphere when the process of secondary aerosol is carried out _2.5 Increase haze pollution and the like. Therefore, how to reduce the volatility of the organic amine on the premise of ensuring the absorption efficiency of the carbon dioxide is a technical problem which needs to be solved urgently at present.

Citation 1 discloses a carbon dioxide capture system comprising: the absorption tower is also provided with a rich amine solution supply pipeline communicated with the first accommodating cavity; the desorption regeneration tower is provided with a lean solution supply pipeline communicated with the second accommodating cavity; the compression enthalpy-increasing device comprises a first compression enthalpy-increasing unit, wherein the first compression enthalpy-increasing unit comprises a first heat exchanger, a first compressor and a second heat exchanger, the first heat exchanger is arranged on an amine-rich solution supply pipeline and used for heating a carbon dioxide-rich absorption liquid in the amine-rich solution supply pipeline, and the second heat exchanger is arranged on a lean solution supply pipeline and used for cooling a carbon dioxide-poor absorption liquid in the lean solution supply pipeline. However, the method aims to solve the problems of high energy consumption and high amine consumption of the carbon capture technology to a certain extent, but the method has a complex structure and can be realized only by arranging a plurality of heat exchangers.

Citation 2 discloses a carbon dioxide capture system and method. The carbon dioxide capture system comprises a desorption tower, an absorption tower and a first heat exchanger; the absorption tower is used for enabling the lean amine solution to absorb carbon dioxide in the flue gas and generate a rich amine solution, the desorption tower is used for desorbing the rich amine solution into the lean amine solution and the carbon dioxide, and the desorption tower is in circulating communication with the absorption tower and is used for circulating circulation of the amine solution; the first heat exchanger comprises a first channel and a second channel, one end of the first channel is used for communicating a smoke source, the other end of the first channel is communicated with a smoke inlet of the absorption tower, the second channel is communicated with the desorption tower in a circulating mode, smoke passing through the first channel is in heat exchange with media in the second channel, and heat is provided for the desorption tower. Although the method can save energy consumption to a certain extent, the method cannot reduce the volatilization amount of the organic amine.

The cited documents are:

citation 1: CN 114367187A

Citation 2: CN 113368683A

Disclosure of Invention

Problems to be solved by the invention

In view of the technical problems in the prior art, for example, the prior art for capturing carbon dioxide has the defect of large volatilization amount of organic amine, the invention firstly provides an absorption device and a carbon dioxide capturing system. The absorption device and the carbon dioxide trapping system can reduce the volatilization amount of organic amine on the premise of ensuring high-efficiency and low-cost trapping of carbon dioxide.

Furthermore, the invention also provides a carbon dioxide trapping method which is simple and feasible and occupies a small area.

Means for solving the problems

[1] An absorbent device, comprising:

a first-stage absorption tower, wherein a first-stage absorbent can be introduced into the first-stage absorption tower,

a secondary absorption tower, wherein a secondary absorbent can be introduced into the secondary absorption tower,

a flue gas pipeline connecting the primary absorption tower and the secondary absorption tower; and the number of the first and second groups,

optionally a circulation cooling module connected inside and/or outside the secondary absorption column, wherein,

the primary absorbent and the secondary absorbent are the same or different, and in the primary absorption tower and the secondary absorption tower, the primary absorbent and the secondary absorbent absorb carbon dioxide in the flue gas and generate a rich amine solution or a split-phase rich amine solution; and also,

the circulating cooling assembly can cool the rich amine solution or the split-phase rich amine solution generated by the secondary absorption tower and then convey the cooled rich amine solution back to the secondary absorption tower.

[2]According to the above [1]]The absorption device, wherein the volume of the primary absorption tower is V _a The volume of the secondary absorption tower is V _b Then the following relationship exists:

V _a ≥2V _b 。

[3]according to the above [1]]Or [2 ]]The absorption device is characterized in that the saturated vapor pressure of the primary absorbent in the primary absorption tower at 20-40 ℃ is P _a The saturated vapor pressure of the secondary absorbent in the secondary absorption tower at 20-40 ℃ is P _b Then the following relationship exists:

P _a ≥P _b 。

[4] the absorption device according to any one of the above [1] to [3], wherein the primary absorbent and/or the secondary absorbent comprises an organic amine absorbent and/or a lean amine solution, and preferably, the organic amine absorbent comprises one or a combination of two or more of a non-phase-change absorbent and a phase-change absorbent.

[5] The absorption apparatus according to any one of the above [1] to [4], wherein when the primary absorbent and/or the secondary absorbent comprises a phase-change absorbent, a phase separator is further disposed outside the primary absorption tower and/or the secondary absorption tower, and the phase separator is used for separating the phase-separated rich amine solution generated by the primary absorption tower and/or the secondary absorption tower.

[6] The absorption apparatus according to any one of the above [1] to [5], wherein the primary absorption column and/or the secondary absorption column comprises: the spraying component, the condensing device and at least one layer of packing layer; wherein,

the spraying assembly and the condensing device are positioned at the top of the primary absorption tower and/or the secondary absorption tower;

the packing layer is positioned in the middle of the first-stage absorption tower and/or the second-stage absorption tower.

[7] A carbon dioxide capture system, comprising: the absorption apparatus and desorption apparatus as set forth in any one of the above [1] to [6], the desorption apparatus being configured to resolve the rich amine solution into a lean amine solution and carbon dioxide; wherein,

the absorption device is circularly connected with the desorption device; so that the rich amine solution produced by the absorption unit can be delivered to the desorption unit and the lean amine solution produced by the desorption unit can be delivered to the absorption unit.

[8] A carbon dioxide capture method for capturing carbon dioxide by the carbon dioxide capture system according to [7], the method comprising:

conveying the flue gas to an absorption device, wherein the absorption device comprises a primary absorption tower and a secondary absorption tower;

introducing a first-stage absorbent into the first-stage absorption tower, and introducing a second-stage absorbent into the second-stage absorption tower;

in the primary absorption tower and the secondary absorption tower, the primary absorbent and the secondary absorbent absorb carbon dioxide in the flue gas and generate a rich amine solution or a split-phase rich amine solution;

conveying the rich amine solution generated by the primary absorption tower or the split-phase rich amine solution generated by the primary absorption tower to a desorption device for analysis to obtain a lean amine solution and carbon dioxide;

optionally, the rich amine solution or the split-phase rich amine solution generated by the secondary absorption tower is cooled by a circulating cooling assembly and then is conveyed back to the secondary absorption tower;

and conveying the lean amine solution to the primary absorption tower and/or the secondary absorption tower, and enabling the lean amine solution to continuously absorb the carbon dioxide and generate a rich amine solution or a split-phase rich amine solution.

[9] And the carbon dioxide capturing method according to the item [8], wherein after the secondary absorption tower is saturated in absorption, the circulating cooling assembly is stopped to cool, and the rich amine solution generated by the secondary absorption tower or the rich amine solution obtained by separating the split-phase rich amine solution generated by the secondary absorption tower is conveyed to a desorption device for desorption, so that the lean amine solution and the carbon dioxide are obtained.

[10] The carbon dioxide capturing method according to the above [8] or [9], wherein when the primary absorbent and/or the secondary absorbent used comprises a phase change absorbent, the primary absorbent and/or the secondary absorbent absorbs carbon dioxide in the flue gas and generates a phase-separated rich amine solution;

and separating the phase-separated rich amine solution generated in the primary absorption tower and/or the secondary absorption tower by using a phase separator.

ADVANTAGEOUS EFFECTS OF INVENTION

The absorption device and the carbon dioxide capture system can increase the gas-liquid retention time of the flue gas and the absorbent, and promote the capture efficiency of the absorption liquid on the carbon dioxide. Moreover, the absorption device and the carbon dioxide trapping system can reduce the volatilization amount of the organic amine on the premise of ensuring the efficient and low-cost trapping of the carbon dioxide.

Furthermore, the method for capturing the carbon dioxide is simple and easy to implement, occupies a small space, and can capture the carbon dioxide in large batch.

Drawings

FIG. 1 shows a schematic view of an absorbent device according to an embodiment of the invention;

FIG. 2 shows a schematic view of an absorbent device according to another embodiment of the invention;

FIG. 3 shows a schematic diagram of a carbon dioxide capture system of an embodiment of the present invention;

FIG. 4 shows a schematic diagram of a carbon dioxide capture system of another embodiment of the present invention;

the reference numbers illustrate:

1001: a first absorption tower; 1002: a second absorption tower; 1003. 1005: a condensing unit;

1006. 1004: a spraying device; 1013: a circulating cooling assembly;

1007. 1008, 1009, 1010, 1025, 1026: a valve;

1011. 1012, 1023: a power plant; 1014. 1015: a condenser;

1022: a first-stage phase splitter; 1024: a secondary phase splitter; 1019: a desorption device.

Detailed Description

Various exemplary embodiments, features and aspects of the invention will be described in detail below. The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In other instances, methods, means, devices and steps which are well known to those skilled in the art have not been described in detail so as not to obscure the invention.

All units used in the invention are international standard units unless otherwise stated, and numerical values and numerical ranges appearing in the invention should be understood to include systematic errors inevitable in industrial production.

A first aspect of the present invention is an absorbent device, as shown in fig. 1. The absorption apparatus includes a primary absorption tower 1001, a secondary absorption tower 1002, an optional circulating cooling unit 1013, and the like, and specifically, the absorption apparatus includes:

a primary absorption tower 1001, wherein a primary absorbent can be introduced into the primary absorption tower 1001,

a secondary absorption tower 1002, wherein a secondary absorbent can be introduced into the secondary absorption tower 1002,

a flue gas duct connecting the primary absorption tower 1001 and the secondary absorption tower 1002; and the number of the first and second groups,

an optional recycle cooling module 1013, said recycle cooling module 1013 being coupled to the interior and/or exterior of said secondary absorber 1002, wherein,

the primary absorbent and the secondary absorbent are the same or different, and in the primary absorption tower 1001 and the secondary absorption tower 1002, the primary absorbent and the secondary absorbent absorb carbon dioxide in the flue gas and generate a rich amine solution or a phase-separated rich amine solution; and also,

the circulating cooling assembly 1013 can cool the rich amine solution or the phase-separated rich amine solution generated by the secondary absorption tower 1002 and return the cooled rich amine solution to the secondary absorption tower 1002.

The carbon dioxide capture system can increase the gas-liquid retention time of the flue gas and the absorbent, and promote the capture efficiency of the absorption liquid on the carbon dioxide. Moreover, the carbon dioxide trapping system can reduce the volatilization amount of organic amine on the premise of ensuring the efficient and low-cost trapping of carbon dioxide.

In the present invention, the primary absorption tower 1001 is a device for absorbing carbon dioxide in flue gas. The primary absorber 1001 may include a flue gas inlet, a flue gas outlet, a primary absorbent inlet, and a rich amine solution outlet. The flue gas inlet is located at the bottom of the primary absorber 1001 for the purpose of flue gas inflow. The flue gas outlet is located at the top of the primary absorber 1001 for the purpose of letting out flue gas. In the primary absorber 1001, the primary absorbent flows from the primary absorbent inlet to the bottom of the tower, and the flue gas flows from the flue gas inlet to the flue gas outlet. Thereby, the flue gas flowing into the primary absorption tower 1001 is brought into sufficiently countercurrent contact with the primary absorbent, and the carbon dioxide in the flue gas is absorbed by the primary absorbent, becomes a rich amine solution or a phase-separated rich amine solution, and flows out from the rich amine solution outlet.

In the present invention, the secondary absorption tower 1002 is a device for absorbing carbon dioxide in flue gas. The secondary absorber 1002 may include a flue gas inlet, a flue gas vent, a secondary absorbent inlet, and a rich amine solution outlet. The flue gas inlet is located at the bottom of the secondary absorption tower in order to allow flue gas discharged from the flue gas outlet of the primary absorption tower 1001 to flow into the secondary absorption tower 1002. The flue gas evacuation port is located at the top of the secondary absorption tower 1002, in order to evacuate flue gas that cannot be finally treated. In the secondary absorption tower 1002, the secondary absorbent flows from the secondary absorbent inlet to the bottom of the tower, and the flue gas flows from the flue gas inlet to the flue gas outlet. Thereby, the flue gas flowing into the secondary absorption tower 1002 is brought into sufficiently countercurrent contact with the secondary absorbent, and the carbon dioxide in the flue gas is absorbed by the secondary absorbent to become a rich amine solution or a phase-separated rich amine solution, and flows out from the rich amine solution outlet. The main purpose of the secondary absorption tower 1002 of the present invention is to reduce the amount of solvent entrained in the flue gas while realizing the decarbonization of the flue gas by a lower absorption temperature.

Further, in the present invention, the circulating cooling assembly 1013 is connected to the inside and/or outside of the secondary absorption tower 1002, wherein when the valve 1025 is opened, the circulating cooling assembly 1013 can cool the rich amine solution or the separated phase rich amine solution generated by the secondary absorption tower 1002 through the power plant 1012 (such as a pump, etc.) and then return the cooled rich amine solution or separated phase rich amine solution to the secondary absorption tower 1002. The circulating cooling assembly 1013 may be a circulating condenser in the present invention.

In some specific embodiments, let the volume of the primary absorption column 1001 be V _a The volume of the secondary absorption tower 1002 is V _b Then the following relationship exists:

V _a ≥2V _b 。

when V is _a ≥2V _b In the process, the function of the secondary absorption tower 1002 can be exerted most effectively, so that the amount of the solvent carried in the flue gas can be reduced while the decarburization of the flue gas is realized through lower absorption temperature.

Further, in the present invention, the saturated vapor pressure of the primary absorbent in the primary absorption tower 1001 at 20 to 40 ℃ is set to P _a The saturated vapor pressure of the secondary absorbent in the secondary absorption tower 1002 at 20-40 ℃ is P _b Then the following relationship exists:

P _a ≥P _b 。

in the present invention, the higher the vapor pressure in secondary absorber 1002, the greater the solvent volatilization loss. By steaming in the secondary absorption column 1002The gas pressure is less than that of the first-stage absorption tower 1001, which is advantageous for reducing the volatilization loss of the solvent. Generally, the means to achieve low vapor pressure is to lower the temperature of secondary absorber 1002 or to change the solvent composition. Since the temperature in the first-stage absorption tower 1001 is different from the temperature in the second-stage absorption tower 1002, the difference in temperature is generally not considered when comparing the saturated vapor pressures. For example, the temperature of primary absorber 1001 may be 40 ℃ and the temperature of secondary absorber 1002 may be 20 ℃, i.e.: saturated vapor pressure P of the first absorbent of the first absorption tower 1001 measured at 40 deg.C _a The saturated vapor pressure P measured at 20 ℃ with the secondary absorbent of the secondary absorption tower 1002 _b Presence of P _a ≥P _b The relationship (2) of (c).

Further, the composition of the primary absorbent and/or the secondary absorbent in the present invention is not particularly limited, and may be an absorbent commonly used in the art. Specifically, the primary absorbent and/or the secondary absorbent comprise an organic amine absorbent and/or a lean amine solution, and preferably, the organic amine absorbent comprises one or a combination of two or more of a non-phase-change absorbent and a phase-change absorbent.

As the organic amine absorbent, in the present invention, it may be one or a combination of two or more of Monoethanolamine (MEA), N-Methyldiethanolamine (MDEA), piperazine (PZ), isobutanol Amine (AMP), hydroxyethyl ethylenediamine (AEEA), diethyl ethanolamine (DEEA), and the like, which are dissolved or diluted with a solvent.

For the phase change absorbent, in the invention, the phase change absorbent can be one of a composite organic amine phase change absorbent, a phase change absorbent composed of an organic amine absorbent and a phase separation absorbent, and a phase change absorbent composed of a composite organic amine and an ionic liquid, and has the performance of layering according to the concentration of carbon dioxide after absorbing the carbon dioxide.

The composite organic amine phase-change absorbent is prepared by mixing one or more organic amines with water and adding other solvents with weak polarity, wherein the absorbent can absorb CO before ₂ The solvent is homogeneous and absorbs CO ₂ The resulting carbamate or the like is then separated from the weakly polar solventUpon exiting, a lean phase and a rich phase are formed. The phase-change solvent is different from the conventional compound amine solvent in that the proportion of the phase-change solvent and the weak polar solvent in the phase-change solvent is more than 30wt% and less than 50 wt%.

The lean amine solution may be a lean amine solution obtained by resolving the rich amine solution in the resolving tower 1019, or may be a lean amine solution remaining after the rich amine solution is separated by the

phase separators

1022 and 1024.

In some specific embodiments, as shown in fig. 2, when the primary absorbent and/or the secondary absorbent includes a phase-change absorbent,

phase separators

1022, 1024 are further disposed outside the primary absorption tower 1001 and/or the secondary absorption tower 1002, and the

phase separators

1022, 1024 are used for separating the phase-separated rich amine solution generated by the primary absorption tower 1001 and/or the secondary absorption tower 1002.

For example, when the composition of the organic amine absorbent, the phase separation absorbent and water is used as the absorbent, the organic amine reacts with CO in the flue gas ₂ The carbamate is generated through the reaction, and the carbamate and the water can be separated through the phase separation agent. After separation, the rich amine solution is generally carbamate and a small amount of unreacted organic amine, and the poor amine solution is organic phase-splitting agent, water and a small amount of unreacted organic amine.

The

phase separators

1022, 1024 are devices for layering the resulting separated phase rich amine solution. The

phase splitters

1022, 1024 include a split phase rich amine solution inlet at the top, a rich amine solution outlet at the bottom rich phase zone, and a lean amine solution outlet at the upper lean phase zone. Since the phase change absorbent is used, the phase-separated rich amine solution generated in the primary absorption tower 1001 and/or the secondary absorption tower 1002 is separated into a rich amine solution and a lean amine solution by the

phase separators

1022 and 1024, wherein the rich amine solution can be transferred to the desorption tower 1019 for desorption by the power unit (e.g., pump or the like) 1011, and the lean amine solution can be mixed with the lean amine solution desorbed by the desorption tower 1019 by the power unit (e.g., pump or the like) 1023 and then transferred to the primary absorption tower 1001 and/or the secondary absorption tower 1002.

In some specific embodiments, the primary absorber 1001 comprises: the spraying assembly 1006, the condensing device 1003 and at least one packing layer; wherein,

the spraying assembly 1006 and the condensing device 1003 are positioned at the top of the primary absorption tower 1001;

the packing layer is located in the middle of the primary absorber 1001.

Further, the secondary absorption tower 1002 includes: a spray assembly 1004, a condensing unit 1005 and at least one filler layer; wherein,

the spray assembly 1004 and the condensing device 1005 are positioned at the top of the secondary absorption tower 1002;

the packing layer is located in the middle of the secondary absorber 1002.

In the present invention, the number of layers of the filler layer in the first-stage absorption tower 1001 and the second-stage absorption tower 1002 is not particularly limited, and may be set as needed.

As shown in fig. 3 and 4, a second aspect of the present invention provides a carbon dioxide capturing system comprising: the absorption apparatus 1019 according to any one of the first aspect of the present invention, wherein the desorption apparatus 1019 is configured to resolve the rich amine solution into a lean amine solution and carbon dioxide; wherein,

the absorption device is circularly connected with the desorption device 1019; so that the rich amine solution produced by the absorption device can be delivered to the desorption device 1019, and the lean amine solution produced by the desorption device 1019 can be delivered to the absorption device.

A third aspect of the present invention provides a carbon dioxide capturing method for capturing with the carbon dioxide capturing system according to the second aspect of the present invention, the capturing method comprising the steps of:

conveying flue gas to an absorption plant, wherein the absorption plant comprises a primary absorption tower 1001 and a secondary absorption tower 1002;

introducing a primary absorbent into the primary absorption tower 1001, and introducing a secondary absorbent into the secondary absorption tower 1002;

in the primary absorption tower 1001 and the secondary absorption tower 1002, the primary absorbent and the secondary absorbent absorb carbon dioxide in the flue gas and generate a rich amine solution or a split-phase rich amine solution;

conveying the rich amine solution generated by the primary absorption tower 1001 or the rich amine solution obtained after separating the split-phase rich amine solution generated by the primary absorption tower 1001 to a desorption device 1019 through a power device 1011 for analysis to obtain a lean amine solution and carbon dioxide;

optionally, the rich amine solution or the phase-separated rich amine solution generated in the secondary absorption tower 1002 is cooled by the circulating cooling assembly 1013 and then returned to the secondary absorption tower 1002;

the lean amine solution is sent to the primary absorption tower 1001 and/or the secondary absorption tower 1002, so that the lean amine solution continues to absorb carbon dioxide and generate a rich amine solution or a phase-separated rich amine solution.

Further, in some specific embodiments, after the secondary absorption tower 1002 is saturated, the circulating cooling assembly 1013 is stopped to cool, and the rich amine solution generated by the secondary absorption tower 1002 or the rich amine solution obtained by separating the phase-separated rich amine solution generated by the secondary absorption tower 1002 is conveyed to the desorption device 1019 through the power device 1011 for desorption, so as to obtain a lean amine solution and carbon dioxide.

In the present invention, the purpose of using the circulating cooling assembly 1013 for cooling is to cool the flue gas CO in the secondary absorption tower 1002 ₂ The concentration is low, the absorption efficiency of the absorbent is reduced, and the rich amine solution or split-phase rich amine solution after one-time absorption is less, which causes the difficulty of subsequent desorption and regeneration and reduces the absorption-regeneration efficiency of the whole process. Through the circulation absorption of using circulation cooling assembly 1013 cooling, organic amine can be fully reacted with CO ₂ The reaction improves the utilization efficiency of the absorbent.

For the use of the circulating cooling module 1013,

valves

1009 and 1026 may be provided on a pipeline connecting the secondary absorption tower 1002 and the desorption tower 1019, when the circulating cooling module 1013 is used for cooling, the

valves

1009 and 1026 may be closed, so that the rich amine solution or the phase-separated rich amine solution generated in the primary absorption tower 1001 is cooled by the circulating cooling module 1013 through the power plant 1012 and then is transported back to the secondary absorption tower 1002, after the secondary absorption tower 1002 is adsorbed to be substantially saturated, the

valves

1009 and 1026 are opened, and the obtained rich amine solution or the phase-separated rich amine solution is transported to the next process.

The method for determining the absorption saturation is not particularly limited in the present invention, and may be determined by CO ₂ Determining the balance load when the CO is ₂ The balance load reaches 0.40-0.50mol CO ₂ The absorption was considered to be saturated per mol of the secondary absorbent (40 ℃ C.).

Further, the primary absorption tower 1001 and the secondary absorption tower 1002 may be performed asynchronously. Specifically, the rich amine solution or the layered rich amine solution in the secondary absorption tower 1002 is circulated through the circulation cooling assembly 1013 while the CO of the rich amine solution or the layered rich amine solution in the secondary absorption tower 1002 is circulated ₂ The balance load reaches 0.40-0.50mol CO ₂ When the concentration of the second-stage absorbent is/mol (40 ℃),

valves

1009 and 1026 of the passage for conveying the rich amine solution in the second-stage absorption tower 1002 or the rich amine solution obtained by separating the phase-separated rich amine solution generated by the second-stage absorption tower 1002 to the desorption tower 1019 are opened, and a valve 1010 of the passage for conveying the lean amine solution of the desorption device 1019 to the second-stage absorption tower 1002 is opened. Then, the valve 1007 for delivering the rich amine solution in the primary absorption tower 1001 or the rich amine solution obtained by separating the phase-separated rich amine solution generated by the primary absorption tower 1001 to the channel of the desorption device is closed, and the valve 1008 for delivering the lean amine solution of the desorption device 1019 to the channel of the primary absorption tower 1001 is closed.

When CO is contained in the rich amine solution or the split-phase rich amine solution in the secondary absorption tower 1002 ₂ The balance load is reduced to 0.05-0.10mol CO ₂ When the/mol of the secondary absorbent is at 40 ℃, the rich amine solution in the secondary absorption tower 1002 or the rich amine solution obtained after the split-phase rich amine solution generated by the secondary absorption tower 1002 is separated and is conveyed to the

valves

1009 and 1026 on the channel of the desorption device 1019 are closed, and the valve 1010 on the channel of the desorption device 1019 and the channel of the secondary absorption tower 1002 is closed; and rich amine solution in the primary absorption tower 1001, or to the secondary absorptionA valve 1007 on a channel for conveying the rich amine solution generated by the separation tower 1002 to the desorption device 1019 is opened, and a valve 1008 on a channel for conveying the lean amine solution of the desorption device 1019 to the primary absorption tower 1001 is opened. The maximum of the solvent absorption efficiency can be realized by controlling the flow-through time by using the valve, and the first-stage absorbent and the second-stage absorbent in the first-stage absorption tower 1001 and the second-stage absorption tower 1002 can be recycled, so that the maximum of the process efficiency is realized.

Specifically, in some embodiments, when the primary absorbent and the secondary absorbent are the same or different, but both are non-phase-change absorbents, the specific implementation method is:

the desulfurized, denitrated and dedusted coal-fired or gas-fired flue gas passes through the primary absorption tower 1001 and is conveyed to the secondary absorption tower 1002 through a flue gas pipeline. Introducing a primary absorbent into the primary absorption tower 1001, introducing a secondary absorbent into the secondary absorption tower 1002, and in the primary absorption tower 1001 and the secondary absorption tower 1002, the primary absorbent and the secondary absorbent absorb carbon dioxide in flue gas and generate an amine-rich solution.

The rich amine solution generated in the primary absorption tower 1001 enters a subsequent desorption device 1019 for desorption, and a lean amine solution and carbon dioxide are obtained. The desorbed lean amine solution is condensed by

condensers

1014 and 1015 and then returns to the corresponding primary absorption tower 1001 and/or secondary absorption tower 1002 respectively to form a circulating carbon dioxide capture passage.

The rich amine solution generated by the secondary absorption tower 1002 is cooled by the circulating cooling assembly 1013 and then is delivered to the secondary absorption tower 1002. And after the secondary absorption tower 1002 is saturated, stopping using the circulating cooling assembly 1013 to cool, and conveying the rich amine solution generated by the secondary absorption tower 1002 to the desorption device 1019 through the power device for desorption to obtain a lean amine solution and carbon dioxide. The desorbed lean amine solution is condensed by

condensers

In other specific embodiments, the primary absorbent and the secondary absorbent are the same or different, and when the primary absorbent and/or the secondary absorbent used comprises a phase change absorbent, the primary absorbent and/or the secondary absorbent absorbs carbon dioxide from the flue gas and produces a phase-separated rich amine solution; the phase separated rich amine solution produced in the primary absorption column 1001 and/or the secondary absorption column 1002 is separated by

phase separators

1022, 1024.

The specific implementation method comprises the following steps: the flue gas of the coal or gas after desulfurization, denitrification and dust removal passes through the primary absorption tower 1001 and is conveyed to the secondary absorption tower 1002 through a flue gas pipeline. Introducing a primary absorbent into the primary absorption tower 1001, introducing a secondary absorbent into the secondary absorption tower 1002, and in the primary absorption tower 1001 and/or the secondary absorption tower 1002, the primary absorbent and/or the secondary absorbent absorb carbon dioxide in flue gas and generate a phase-separated rich amine solution. The separated phase rich amine solution generated by the secondary absorption tower 1002 is cooled under the action of the circulating cooling component 1013 and then is conveyed to the secondary absorption tower 1002. The phase-separated rich amine solution produced by the primary absorption column 1001 and/or the secondary absorption column 1002 is separated by

phase separators

1022, 1024 to obtain a rich amine solution and a lean amine solution.

Specifically, when the primary absorbent contains a phase-change absorbent and the secondary absorbent contains a non-phase-change absorbent, the phase-separated rich amine solution produced by the primary absorption tower 1001 is separated by the primary phase separator 1022 to obtain a rich amine solution and a lean amine solution. The rich amine solution generated by the first phase separator 1022 is delivered to the desorption unit 1019 for desorption, and the lean amine solution generated by the first phase separator 1022 and the lean amine solution generated after desorption by the desorption unit 1019 may be mixed and condensed by the

condensers

1014 and 1015, and then delivered to the first absorption tower 1001 and/or the second absorption tower 1002.

The rich amine solution generated by the secondary absorption tower 1002 is cooled by the circulating cooling assembly 1013 and then is delivered to the secondary absorption tower 1002. And after the secondary absorption tower 1002 is saturated in absorption, stopping using the circulating cooling assembly 1013 to cool, and conveying the rich amine solution generated by the secondary absorption tower 1002 to the desorption device 1019 through the power device for desorption to obtain a lean amine solution and carbon dioxide. The desorbed lean amine solution is condensed by

condensers

When the primary absorbent is a non-phase-change absorbent and the secondary absorbent contains a phase-change absorbent, the primary absorbent is introduced into the primary absorption tower 1001, the secondary absorbent is introduced into the secondary absorption tower 1002, and in the primary absorption tower 1001 and the secondary absorption tower 1002, the primary absorbent and the secondary absorbent absorb carbon dioxide in the flue gas and generate a rich amine solution. The rich amine solution generated in the primary absorption tower 1001 is transported to the desorption device 1019 through a power device for desorption, and a lean amine solution and carbon dioxide are obtained. The desorbed lean amine solution is condensed by

condensers

The separated phase rich amine solution generated by the secondary absorption tower 1002 is cooled under the action of the circulating cooling component 1013 and then is conveyed to the secondary absorption tower 1002. And after the secondary absorption tower 1002 is saturated in absorption, stopping using the circulating cooling assembly 1013 to cool, and separating the phase-separated rich amine solution generated in the secondary absorption tower 1002 by the secondary phase separator 1024 to obtain a rich amine solution and a lean amine solution, wherein the rich amine solution enters a subsequent desorption device 1019 to be desorbed to obtain the lean amine solution and carbon dioxide. The lean amine solution separated by the secondary phase separator 1024 and desorbed by the desorption device 1019 is condensed by the

condensers

1014 and 1015 and then respectively returned to the corresponding primary absorption tower 1001 and/or secondary absorption tower 1002 to form a circulating carbon dioxide capture passage.

When the primary absorbent and the secondary absorbent are both phase-change absorbents, the phase-separated rich amine solution generated by the primary absorption tower 1001 is separated by the primary phase separator 1022 to obtain a rich amine solution and a lean amine solution. The rich amine solution generated by the first phase separator 1022 is delivered to the desorption device 1019 for desorption, and the lean amine solution generated by the first phase separator 1022 and the lean amine solution generated by the desorption device 1019 after desorption can be mixed and delivered to the first absorption tower 1001 and/or the second absorption tower 1002 after being condensed by the

condensers

1014 and 1015.

The separated phase rich amine solution generated by the secondary absorption tower 1002 is cooled under the action of the circulating cooling component 1013 and then is conveyed to the secondary absorption tower 1002. And after the secondary absorption tower 1002 is saturated in absorption, stopping using the circulating cooling assembly 1013 to cool, and separating the phase-separated rich amine solution generated by the secondary absorption tower 1002 by using the secondary phase separator 1024 to obtain a rich amine solution and a lean amine solution, wherein the rich amine solution enters a subsequent desorption device 1019 to be desorbed to obtain the lean amine solution and carbon dioxide. The lean amine solution separated by the second-stage phase separator 1024 and the lean amine solution desorbed by the desorption device 1019 are condensed by the

condensers

1014 and 1015 and then respectively returned to the corresponding first-stage absorption tower 1001 and/or second-stage absorption tower 1002, so as to form a circulating carbon dioxide capture passage.

Examples

Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

In the examples, the amount of primary absorbent is determined by the gas-liquid ratio, which is generally controlled between 200 and 300, for example, gas throughput 120000Nm ³ The dosage of the first-stage absorbent is 400-600 m ³ /h。

Example 1

In this example 1, the primary absorption tower and the secondary absorption tower used a Monoethanolamine (MEA) solution with a mass concentration of 30% as the primary absorbent and the secondary absorbent. The coal or gas flue gas after desulfurization, denitrification and dust removal passes through the primary absorption tower and is conveyed to the secondary absorption tower through a flue gas pipeline. Introducing 30% Monoethanolamine (MEA) solution into the first-stage absorption tower, and introducing 30% Monoethanolamine (MEA) solution into the second-stage absorption tower. In the first-stage absorption tower and the second-stage absorption tower, monoethanolamine (MEA) solution and Monoethanolamine (MEA) solution absorb carbon dioxide in the flue gas and generate rich amine solution.

The volume of the first-stage absorption tower is more than 2 times of that of the second-stage absorption tower, more than 2 layers of fillers are arranged in the first-stage absorption tower, and more than 1 layer of fillers are arranged in the second-stage absorption tower. The top of the first-stage absorption tower and the top of the second-stage absorption tower comprise a spraying device and a condensing device, a circulating condenser is connected outside the second-stage absorption tower, and the rich amine solution generated by the second-stage absorption tower is cooled and then conveyed to the second-stage absorption tower, and the rich amine solution CO in the second-stage absorption tower ₂ The balance load does not reach 0.40mol of CO ₂ And (6) adding the rich amine solution in the first-stage absorption tower into a subsequent desorption tower for regeneration at 40 ℃ of the second-stage absorbent. And the rich amine solution generated in the primary absorption tower simultaneously enters a subsequent desorption device for regeneration, and the desorbed lean amine solutions are condensed by a condenser and then respectively return to the corresponding primary absorption towers.

Wherein, in the first-stage absorption tower: the saturated vapor pressure (40 ℃ C.) of the Monoethanolamine (MEA) solution was 5.22kPa; in the secondary absorption column, the saturated vapor pressure (20 ℃ C.) of the Monoethanolamine (MEA) solution was 1.65kPa.

Example 2

In example 2, the primary absorption tower used a Monoethanolamine (MEA) solution with a mass concentration of 30% as the primary absorbent, and the secondary absorption tower used an N-Methyldiethanolamine (MDEA) solution with a mass concentration of 30% as the secondary absorbent. The coal or gas flue gas after desulfurization, denitrification and dust removal passes through the primary absorption tower and is conveyed to the secondary absorption tower through a flue gas pipeline. A Monoethanolamine (MEA) solution with a mass concentration of 30% was introduced into the primary absorption tower, and an N-Methyldiethanolamine (MDEA) solution with a mass concentration of 30% was introduced into the secondary absorption tower. In the primary absorption tower and the secondary absorption tower, the Monoethanolamine (MEA) solution and the N-Methyldiethanolamine (MDEA) solution absorb carbon dioxide in the flue gas and generate a rich amine solution.

The volume of the first-stage absorption tower is more than 2 times of that of the second-stage absorption tower, more than 2 layers of fillers are arranged in the first-stage absorption tower, and more than 1 layer of fillers are arranged in the second-stage absorption tower. The top of the first-stage absorption tower and the top of the second-stage absorption tower comprise a spraying device and a condensing device, the circulating condenser is connected to the outside of the second-stage absorption tower, and the rich amine solution generated by the second-stage absorption tower is cooled and then is conveyed to the second-stage absorption tower. And the rich amine solution in the first-stage absorption tower simultaneously enters a subsequent desorption device for regeneration, and the desorbed lean amine solution is conveyed to the first-stage absorption tower through a metering pump. And closing a valve on a channel for conveying the rich amine solution to the desorption device in the secondary absorption tower, and closing a valve on a channel for conveying the lean amine solution to the secondary absorption tower.

The rich amine solution in the secondary absorption tower is circulated through a pump and a circulating condenser, and when the rich amine solution in the secondary absorption tower is CO ₂ The balance load reaches 0.40-0.50mol CO ₂ At 40 ℃, the valve on the channel for conveying the rich amine solution to the desorption device in the secondary absorption tower is opened, and the valve on the channel for conveying the lean amine solution to the secondary absorption tower in the desorption device is opened. Then, the valve on the passage of the rich amine solution in the primary absorption tower to the desorption device is closed, and the valve on the passage of the lean amine solution in the desorption device to the primary absorption tower is closed. When the amine-rich solution CO is in the secondary absorption tower ₂ The balance load is reduced to 0.05-0.10mol of CO ₂ The temperature of the secondary absorption tower is 40 ℃, a valve on a channel for conveying the rich amine solution to the desorption device in the secondary absorption tower is closed, and a valve on a channel for conveying the lean amine solution of the desorption device to the secondary absorption tower is closed; and the valve on the channel for conveying the rich amine solution to the desorption device in the first-stage absorption tower is opened, and the valve on the channel for conveying the lean amine solution to the first-stage absorption tower in the desorption device is opened.

Wherein, in the first-stage absorption tower: the saturated vapor pressure (40 ℃ C.) of the Monoethanolamine (MEA) solution was 5.22kPa; in the secondary absorption tower, the saturated vapor pressure (20 ℃) of the N-Methyldiethanolamine (MDEA) solution was 1.64kPa.

Example 3

In this example 3, the primary absorption tower used a mixed solution of Monoethanolamine (MEA) and N-Methyldiethanolamine (MDEA) as a primary absorbent. In the primary absorbent, the mass concentration of Monoethanolamine (MEA) is 30%, the mass concentration of N-Methyldiethanolamine (MDEA) is 30%, and the following are recorded as: 30% MEA/30% MDEA; the secondary absorption tower uses a 30% by mass N-Methyldiethanolamine (MDEA) solution as a secondary absorbent. The coal or gas flue gas after desulfurization, denitrification and dust removal passes through the primary absorption tower and is conveyed to the secondary absorption tower through a flue gas pipeline. Introducing 30% MEA/30% MDEA in the primary absorption column and 30% N-Methyldiethanolamine (MDEA) solution in the secondary absorption column. In the primary and secondary absorption towers, 30% MEA/30% MDEA and 30% N-Methyldiethanolamine (MDEA) solution absorbs carbon dioxide in the flue gas and generates a rich amine solution.

The volume of the first-stage absorption tower is more than 2 times of that of the second-stage absorption tower, more than 2 layers of fillers are arranged in the first-stage absorption tower, and more than 1 layer of fillers are arranged in the second-stage absorption tower. The top of the first-stage absorption tower and the top of the second-stage absorption tower comprise a spraying device and a condensing device, the circulating condenser is connected to the outside of the second-stage absorption tower, and the rich amine solution generated by the second-stage absorption tower is cooled and then is conveyed to the second-stage absorption tower. And the rich amine solution of the first-stage absorption tower simultaneously enters a subsequent desorption device for regeneration, and the desorbed lean amine solution respectively returns to the corresponding first-stage absorption tower through a metering pump. And closing a valve on a channel for conveying the rich amine solution to the desorption device in the secondary absorption tower, and closing a valve on a channel for conveying the lean amine solution to the secondary absorption tower in the desorption device.

The rich amine solution in the secondary absorption tower is circulated through a pump and a circulating condenser, and when the rich amine solution in the secondary absorption tower is CO ₂ The balance load reaches 0.40-0.50mol CO ₂ At 40 ℃, the valve on the channel for conveying the rich amine solution to the desorption device in the secondary absorption tower is opened, and the valve on the channel for conveying the lean amine solution to the secondary absorption tower in the desorption device is opened. Then, the valve on the channel for conveying the rich amine solution to the desorption device in the first-stage absorption tower is closed, and the valve on the channel for conveying the lean amine solution to the first-stage absorption tower in the desorption device is closed. When the amine-rich solution CO is in the secondary absorption tower ₂ The balance load is reduced to 0.05-0.10mol of CO ₂ The temperature of the secondary absorption tower is 40 ℃, a valve on a channel for conveying the rich amine solution to the desorption device in the secondary absorption tower is closed, and a valve on a channel for conveying the lean amine solution to the secondary absorption tower in the desorption device is closed; and rich amine in the first-stage absorption towerThe valve on the passage of the solution to the desorption unit is opened and the valve on the passage of the lean amine solution from the desorption unit to the primary absorption tower is opened.

Wherein, in the first-stage absorption tower: the saturated vapor pressure (40 ℃) of the Monoethanolamine (MEA)/N-Methyldiethanolamine (MDEA) solution was 3.00kPa; in the secondary absorption tower, the saturated vapor pressure (20 ℃) of the N-Methyldiethanolamine (MDEA) solution is 1.64kPa.

Example 4

In example 4, the primary absorption column used a mixed solution of Monoethanolamine (MEA) and isobutanol Amine (AMP) as a primary absorbent. In the primary absorbent, monoethanolamine (MEA) was 30% by mass and Monoethanolamine (MEA) was 30% by mass, and these were recorded as: 30% MEA/30% AMP; the secondary absorption column uses a mixed solution of Piperazine (PZ) and isobutanol Amine (AMP) as a secondary absorbent. In the secondary absorbent, the mass concentration of Piperazine (PZ) is 30%, the mass concentration of isobutanolamine (AMP) is 30%, and the following are recorded: 30% PZ/30% AMP. The coal or gas flue gas after desulfurization, denitrification and dust removal passes through the primary absorption tower and is conveyed to the secondary absorption tower through a flue gas pipeline. The MDEA was measured by 30% AMP/30% in the first-stage absorption column, and the AMP was measured by 30% PZ/30% in the second-stage absorption column. In the primary and secondary absorption columns, 30% AMP/30% MDEA and 30% PZ/30% AMP absorbs carbon dioxide in the flue gas and produces a rich amine solution.

The volume of the first-stage absorption tower is more than 2 times of that of the second-stage absorption tower, more than 2 layers of fillers are arranged in the first-stage absorption tower, and more than 1 layer of fillers are arranged in the second-stage absorption tower. The top of the first-stage absorption tower and the top of the second-stage absorption tower comprise a spraying device and a condensing device, the circulating condenser is connected to the outside of the second-stage absorption tower, and the rich amine solution generated by the second-stage absorption tower is cooled and then is conveyed to the second-stage absorption tower. And the rich amine solution of the primary absorption tower simultaneously enters a subsequent desorption device for regeneration, and the desorbed lean amine solution is conveyed to the primary absorption tower through a metering pump. And closing a valve on a channel for conveying the rich amine solution to the desorption device in the secondary absorption tower, and closing a valve on a channel for conveying the lean amine solution to the secondary absorption tower.

In the secondary absorption towerThe rich amine solution is circulated by a pump and a circulating condenser, and when the rich amine solution CO is in the secondary absorption tower ₂ The balance load reaches 0.40-0.50mol CO ₂ At 40 ℃ for the/mol of the secondary absorbent, the valve on the channel for conveying the rich amine solution to the desorption device in the secondary absorption tower is opened, and the valve on the channel for conveying the lean amine solution of the desorption device to the secondary absorption tower is opened. Then, the valve on the channel for conveying the rich amine solution to the desorption device in the first-stage absorption tower is closed, and the valve on the channel for conveying the lean amine solution to the first-stage absorption tower in the desorption device is closed. When the amine-rich solution CO exists in the secondary absorption tower ₂ The balance load is reduced to 0.05-0.10mol CO ₂ The temperature of the secondary absorption tower is 40 ℃, a valve on a channel for conveying the rich amine solution to the desorption device in the secondary absorption tower is closed, and a valve on a channel for conveying the lean amine solution to the secondary absorption tower in the desorption device is closed; and the valve on the channel for conveying the rich amine solution to the desorption device in the primary absorption tower is opened, and the valve on the channel for conveying the lean amine solution to the primary absorption tower in the desorption device is opened.

Wherein, in the first-stage absorption tower: 30% MEA/30% the saturated vapor pressure (40 ℃) of the AMP solution was 3.00kPa; in the secondary absorption column, 30% PZ/30% AMP was saturated with vapor pressure (20 ℃ C.) of 1.05kPa.

Example 5

In this example 5, the primary absorption tower used a mixed solution of Monoethanolamine (MEA) and Diethylethanolamine (DEEA) as a primary absorbent. In the primary absorbent, the mass concentration of Monoethanolamine (MEA) is 30%, the mass concentration of Diethylethanolamine (DEEA) is 30%, and is recorded as: 30% MEA/30% DEEA; the secondary absorption tower uses a 30% Diethylethanolamine (DEEA) solution as a secondary absorbent. 30% MEA/30% DEEA was passed through the first absorption column, and 30% Diethylethanolamine (DEEA) solution was passed through the second absorption column. The coal or gas flue gas after desulfurization, denitrification and dust removal passes through the primary absorption tower and is conveyed to the secondary absorption tower through a flue gas pipeline. In the primary absorber, 30% AMP/30% MDEA absorbs carbon dioxide from the flue gas and produces a split-phase rich amine solution. In the secondary absorber, 30% PZ/30% AMP absorbs carbon dioxide in the flue gas and produces a rich amine solution.

The volume of the first-stage absorption tower is more than 2 times of that of the second-stage absorption tower, more than 2 layers of fillers are arranged in the first-stage absorption tower, and more than 1 layer of fillers are arranged in the second-stage absorption tower. The top of the first-stage absorption tower and the top of the second-stage absorption tower comprise a spraying device and a condensing device, and the bottom of the first-stage absorption tower is provided with a first-stage phase separator which is used for separating a phase-separated rich amine solution generated by the first-stage absorption tower to obtain a rich amine solution and a lean amine solution. And the circulating condenser is connected to the outside of the secondary absorption tower, and is used for cooling the rich amine solution generated by the secondary absorption tower and then conveying the rich amine solution to the secondary absorption tower. The rich amine solution of the first-stage phase separator is conveyed to the desorption device for regeneration, the lean amine solution generated by the first-stage phase separator is mixed with the lean amine solution generated after desorption by the desorption device and is conveyed to the first-stage absorption tower through the metering pump, a valve on a channel for conveying the rich amine solution to the desorption device in the second-stage absorption tower is closed, and a valve on a channel for conveying the lean amine solution of the desorption device to the second-stage absorption tower is closed.

The rich amine solution in the secondary absorption tower is circulated through a pump and a circulating condenser, and when the rich amine solution in the secondary absorption tower is CO ₂ The balance load reaches 0.40-0.50mol CO ₂ At 40 ℃, the valve on the channel for conveying the rich amine solution to the desorption device in the secondary absorption tower is opened, and the valve on the channel for conveying the lean amine solution to the secondary absorption tower in the desorption device is opened. Then, the valve on the passage of the rich amine solution in the first phase separator to the desorption device is closed, and the valve on the passage of the lean amine solution in the desorption device to the first absorption tower is closed. When the amine-rich solution CO is in the secondary absorption tower ₂ The balance load is reduced to 0.05-0.10mol CO ₂ The temperature of the secondary absorption tower is 40 ℃, a valve on a channel for conveying the rich amine solution to the desorption device in the secondary absorption tower is closed, and a valve on a channel for conveying the lean amine solution to the secondary absorption tower in the desorption device is closed; and the valve on the channel for conveying the rich amine solution to the desorption device in the first-stage phase separator is opened, and the valve on the channel for conveying the lean amine solution to the first-stage absorption tower in the desorption device is opened.

Wherein, in the first-stage absorption tower: 30% MEA/30% DEEA solution having a saturated vapor pressure (40 ℃) of 3.18kPa; the saturation vapor pressure (20 ℃) of the 30% DEEA solution in the second-stage absorption column was 2.47kPa.

Example 6

In this example 6, the primary absorption tower used a mixed solution of Monoethanolamine (MEA) and Diethylethanolamine (DEEA) as a primary absorbent. In the primary absorbent, the mass concentration of Monoethanolamine (MEA) was 30%, and the mass concentration of Diethylethanolamine (DEEA) was 30%, which are recorded as: 30% MEA/30% DEEA; the secondary absorption tower uses a mixed solution of hydroxyethylethylenediamine (AEEA) and Diethylethanolamine (DEEA) as a secondary absorbent. In the secondary absorbent, the mass concentration of hydroxyethyl ethylenediamine (AEEA) is 30%, and the mass concentration of Diethylethanolamine (DEEA) is 30%, which are recorded as: 30% AEEA/30% DEEA. Passing through the first absorption column 30% MEA/30% DEEA, passing through the second absorption column 30% AEEA/30% DEEA. The coal or gas flue gas after desulfurization, denitrification and dust removal passes through the primary absorption tower and is conveyed to the secondary absorption tower through a flue gas pipeline. At the primary absorber, 30% MEA/30% DEEA absorbs carbon dioxide from the flue gas and produces a split-phase rich amine solution. In the secondary absorption tower, 30% MEA/30%.

The volume of the first-stage absorption tower is more than 2 times of that of the second-stage absorption tower, more than 2 layers of fillers are arranged in the first-stage absorption tower, and more than 1 layer of fillers are arranged in the second-stage absorption tower. The top of the first-stage absorption tower and the top of the second-stage absorption tower comprise a spraying device and a condensing device, the bottom of each of the first-stage absorption tower and the second-stage absorption tower is respectively provided with a first-stage phase separator and a second-stage phase separator, the first-stage phase separator is used for separating a phase-separated rich amine solution generated by the first-stage absorption tower to obtain a rich amine solution and a lean amine solution, and the second-stage phase separator is used for separating a phase-separated rich amine solution generated by the second-stage absorption tower to obtain a rich amine solution and a lean amine solution. And the circulating condenser is connected to the outside of the secondary absorption tower, and the split-phase rich amine solution generated by the secondary absorption tower is cooled and then is conveyed to the secondary absorption tower.

The rich amine solution of the first-stage phase separator is conveyed to a desorption deviceAnd regenerating, mixing the lean amine solution generated by the first-stage phase separator with the lean amine solution generated after the desorption of the desorption device, and conveying the mixed solution to the first-stage absorption tower through a metering pump, closing a valve on a passage for conveying the rich amine solution to the desorption device in the second-stage absorption tower, and closing a valve on a passage for conveying the lean amine solution to the second-stage absorption tower. The split-phase rich amine solution in the secondary absorption tower is circulated through a pump and a circulating condenser, and when the split-phase rich amine solution in the secondary absorption tower is CO ₂ The balance load reaches 0.40-0.50mol CO ₂ When the mol of the secondary absorbent is at 40 ℃, the phase-separated rich amine solution in the secondary absorption tower is separated by a secondary phase separator to obtain a rich amine solution and a lean amine solution.

And opening a valve on a channel for conveying the rich amine solution of the secondary phase separator to the desorption device, and opening a valve on a channel for conveying the lean amine solution of the desorption device to the secondary absorption tower. Then, the valve on the passage of the rich amine solution to the desorption device in the first phase separator is closed, and the valve on the passage of the lean amine solution to the first absorption tower in the desorption device is closed. When the secondary absorption tower is internally divided into phase rich amine solution CO ₂ The balance load is reduced to 0.05-0.10mol CO ₂ The temperature of the secondary phase separator is 40 ℃, a valve on a channel for conveying the rich amine solution to the desorption device in the secondary phase separator is closed, and a valve on a channel for conveying the lean amine solution to the secondary absorption tower in the desorption device is closed; and opening a valve on a channel for conveying the rich amine solution to the desorption device in the primary phase separator, and opening a valve on a channel for conveying the lean amine solution to the primary absorption tower in the desorption device.

Wherein, in the first-stage absorption tower: 30% MEA/30% DEEA solution having a saturated vapor pressure (40 ℃) of 3.18kPa; the saturated vapor pressure (20 ℃ C.) of the AEEA solution was 0.95kPa at 30% MEA/30% in the secondary absorption column.

The above examples of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An absorbent device, comprising:

a flue gas pipeline connecting the primary absorption tower and the secondary absorption tower; and (c) a second step of,

the primary absorbent and the secondary absorbent are the same or different, and in the primary absorption tower and the secondary absorption tower, the primary absorbent and the secondary absorbent absorb carbon dioxide in the flue gas and generate a rich amine solution or a split-phase rich amine solution; and,

2. The absorption apparatus as claimed in claim 1, wherein the primary absorption tower has a volume V _a The volume of the secondary absorption tower is V _b Then the following relationship exists:

V _a ≥2V _b 。

3. the absorption apparatus as claimed in claim 1 or 2, wherein the saturated vapor pressure of the primary absorbent in the primary absorption tower at 20-40 ℃ is P _a The saturated vapor pressure of the secondary absorbent in the secondary absorption tower at 20-40 ℃ is P _b Then the following relationship exists:

P _a ≥P _b 。

4. the absorption apparatus according to any one of claims 1 to 3, wherein the primary and/or secondary absorbent comprises an organic amine absorbent and/or a lean amine solution, preferably wherein the organic amine absorbent comprises one or a combination of two or more of a non-phase change absorbent or a phase change absorbent.

5. The absorption apparatus as claimed in any one of claims 1 to 4, wherein when the primary absorbent and/or the secondary absorbent comprises a phase-change absorbent, a phase separator is further disposed outside the primary absorption tower and/or the secondary absorption tower, and the phase separator is used for separating the phase-separated rich amine solution generated by the primary absorption tower and/or the secondary absorption tower.

6. The absorption apparatus according to any one of claims 1 to 5, wherein the primary absorption tower and/or the secondary absorption tower comprises: the spraying component, the condensing device and at least one layer of packing layer; wherein,

the packing layer is positioned in the middle of the primary absorption tower and/or the secondary absorption tower.

7. A carbon dioxide capture system, comprising: an absorption unit and a desorption unit according to any one of claims 1-6 for resolving the rich amine solution into a lean amine solution and carbon dioxide; wherein,

the absorption device is circularly connected with the desorption device; so that the rich amine solution produced by the absorption device can be delivered to the desorption device and the lean amine solution produced by the desorption device can be delivered to the absorption device.

8. A carbon dioxide capturing method characterized by capturing with the carbon dioxide capturing system according to claim 7, the capturing method comprising the steps of:

9. The carbon dioxide capture method according to claim 8, wherein after the secondary absorption tower is saturated in absorption, the circulating cooling assembly is stopped to cool, and the rich amine solution generated by the secondary absorption tower or the rich amine solution obtained by separating the split-phase rich amine solution generated by the secondary absorption tower is conveyed to a desorption device for desorption, so as to obtain the lean amine solution and the carbon dioxide.

10. A method for capturing carbon dioxide as claimed in claim 8 or 9, characterized in that when the primary and/or secondary absorbent used comprises a phase change absorbent, the primary and/or secondary absorbent absorbs carbon dioxide from the flue gas and generates a resulting phase-separated rich amine solution;