CN115337756B - Absorption device, carbon dioxide capturing system, and carbon dioxide capturing method - Google Patents

Absorption device, carbon dioxide capturing system, and carbon dioxide capturing method Download PDF

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CN115337756B
CN115337756B CN202210985775.3A CN202210985775A CN115337756B CN 115337756 B CN115337756 B CN 115337756B CN 202210985775 A CN202210985775 A CN 202210985775A CN 115337756 B CN115337756 B CN 115337756B
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absorption tower
amine solution
primary
absorbent
rich amine
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CN115337756A (en
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彭悦
詹国雄
陈阵
司文哲
李俊华
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Tsinghua University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/18—Absorbing units; Liquid distributors therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1412—Controlling the absorption process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1425—Regeneration of liquid absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1456—Removing acid components
    • B01D53/1475—Removing carbon dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
    • B01D2252/20—Organic absorbents
    • B01D2252/204—Amines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/40—Capture or disposal of greenhouse gases of CO2

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Gas Separation By Absorption (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention provides an absorption device, a carbon dioxide capturing system and a carbon dioxide capturing method. The absorption device comprises: the primary absorber can be introduced into the primary absorber, the secondary absorber can be introduced into the secondary absorber, and the flue gas pipeline connecting the primary absorber and the secondary absorber is connected; the optional circulating cooling component 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 rich amine solution or split-phase rich amine solution; the circulating cooling component can cool the rich amine solution generated by the secondary absorption tower or the split-phase rich amine solution and then convey the rich amine solution back to the secondary absorption tower. The absorption device and the carbon dioxide trapping system can increase the gas-liquid residence time of the flue gas and the absorbent and promote the trapping efficiency of the absorption liquid on the carbon dioxide.

Description

Absorption device, carbon dioxide capturing system, and carbon dioxide capturing method
Technical Field
The invention relates to an absorption device, a carbon dioxide capturing system and a carbon dioxide capturing method, and belongs to the technical field of carbon dioxide capturing.
Background
The carbon dioxide trapping and sealing technology is a key technology for realizing the emission reduction of the carbon dioxide in the flue gas generated by the coal/gas fired boiler at the present stage. According to the different orders of the carbon dioxide capturing units, the technologies of capturing before combustion, capturing after combustion, oxygen-enriched combustion and the like can be divided. The capturing after combustion has the advantages of high inheritance degree to the original technology and the like because the original technology is not involved in transformation, so that the technology is widely applied in the flue gas decarburization process. According to the difference of carbon dioxide trapping action mechanisms, the following can be classified: chemical/physical absorption methods, physical adsorption methods, membrane separation methods, and the like. Wherein, the chemical absorption method can realize the aim 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 traditional carbon capture system by the absorption method has the limitations of high energy consumption, high amine consumption, high-temperature and easy degradation in industrial application, and greatly limits the large-scale popularization and application of the carbon capture technology by the chemical absorption method, especially the alcohol amine method.
Chemical absorption based on alcohol amine solutions is currently the only carbon dioxide capture method that is commercially available on a large scale, monoethanolamine (MEA 20-30%) is considered the first generation absorbent and is compared as a standard solvent. Although the monoethanolamine has the advantages of high absorption rate, large absorption load, lower volatility and the like, the energy consumption required for the regeneration of the absorption rich amine solution is high, and the energy consumption is usually 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, using a typical monoethanolamine process absorption technology 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, and the combination strength of monoethanolamine and carbon dioxide is modulated by adding a certain amount of sterically hindered amine (such as isobutolamine, AMP) or tertiary amine (such as N, N-dimethylcyclohexylamine, DMCA) and the like, so that the desorption energy consumption and desorption temperature are reduced, but the volatilization amount of organic amine is increased.
The volatilization of the organic amine is one of the main reasons for causing the loss of the active ingredients of the absorbent, and the reduction of the volatilization amount of the organic amine can effectively control the carbon capture operation cost of the organic amine method. The existing absorption tower only utilizes a primary water washing cooler at the top of the tower to reduce the volatilization of the organic amine, but has poor effect of condensing the organic amine aiming at the flue gas with large air quantity and high humidity. In addition, with the enhancement of human environmental awareness and the continuously tightened environmental standards of the state, the volatility and toxicity of the organic amine are more and more emphasized. The volatilization of the organic amine gas into the atmosphere further causes an atmospheric chemical reaction to generate carcinogens such as nitrosamine, and the travel of the secondary aerosol can further cause PM in the atmosphere 2.5 Increase inCausing haze pollution and the like. Therefore, how to reduce the volatility of organic amines while ensuring the carbon dioxide absorption efficiency is a technical problem that needs to be solved at present.
Reference 1 discloses a carbon dioxide capturing system including: 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 the rich amine solution supply pipeline and is used for heating the carbon dioxide-rich absorption liquid in the rich amine solution supply pipeline, and the second heat exchanger is arranged on the lean liquid supply pipeline and is used for cooling the carbon dioxide-lean absorption liquid in the lean liquid supply pipeline. However, the method can solve the problems of high energy consumption and high amine consumption of the carbon capture technology to a certain extent, but has a complex structure and can be realized only by arranging a plurality of heat exchangers.
Reference 2 discloses a carbon dioxide capturing system and method. The carbon dioxide capturing system comprises a resolving 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 rich amine solution, the analysis tower is used for analyzing the rich amine solution into the lean amine solution and the carbon dioxide, and the analysis tower is in circulating communication with the absorption tower and is used for circulating the amine solution; the first heat exchanger comprises a first channel and a second channel, one end of the first channel is used for being communicated with a smoke source, the other end of the first channel is communicated with a smoke inlet of the absorption tower, the second channel is circularly communicated with the analysis tower, and smoke passing through the first channel is in heat exchange with media in the second channel so as to provide heat for the analysis tower. Although the method can save energy to a certain extent, the method can not reduce the volatilization amount of the organic amine.
Citation literature:
citation 1: CN 114367187A
Citation 2: CN 113368683A
Disclosure of Invention
Problems to be solved by the invention
In view of the technical problems existing in the prior art, such as the defect of large volatilization amount of organic amine in the existing carbon dioxide capturing technology, 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 the organic amine on the premise of ensuring high-efficiency and low-cost trapping of carbon dioxide.
Furthermore, the invention also provides a carbon dioxide capturing method which is simple and feasible and occupies a small space.
Solution for solving the problem
[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 pipe connecting the primary absorption tower and the secondary absorption tower; the method comprises the steps of,
optionally a recirculating cooling module connected to the inside and/or outside of 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 rich amine solution or split-phase rich amine solution; and, in addition, the processing unit,
The circulating cooling component can cool the rich amine solution generated by the secondary absorption tower or the split-phase rich amine solution and then convey the rich amine solution back to the secondary absorption tower.
[2]According to [1] above]The absorption device is characterized in that the volume of the primary absorption tower is V a The volume of the secondary absorption tower is V b The following relationship exists:
V a ≥2V b 。
[3]according to [1] above]Or [2 ]]The saidWherein the saturated vapor pressure of the primary absorbent in the primary absorption tower at 20-40 ℃ is set to be P a The saturated vapor pressure of the secondary absorbent in the secondary absorption tower at 20-40 ℃ is P b The following relationship exists:
P a ≥P b 。
[4] the absorption device according to any one of [1] to [3] above, wherein the primary absorbent and/or the secondary absorbent comprises an organic amine absorbent and/or a lean amine solution, preferably 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 according to any one of the above [1] to [4], wherein when the primary absorbent and/or the secondary absorbent comprise a phase-change absorbent, a phase separator for separating a phase-separated rich amine solution produced in the primary absorbent and/or the secondary absorbent is further provided outside the primary absorbent and/or the secondary absorbent.
[6] The absorption apparatus according to any one of the above [1] to [5], wherein the primary absorption tower and/or the secondary absorption tower comprises: the device comprises a spraying assembly, a condensing device and at least one filler 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 primary absorption tower and/or the secondary absorption tower.
[7] A carbon dioxide capture system, comprising: an absorption apparatus and a desorption apparatus as described in any one of the above [1] to [6], wherein the desorption apparatus is for resolving a 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 using the carbon dioxide capturing system according to the above [7], the capturing method comprising the steps of:
delivering the flue gas to an absorption device, wherein the absorption device comprises a primary absorption tower and a secondary absorption tower;
introducing a primary absorbent into the primary absorption tower, and introducing a secondary absorbent into the secondary 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 rich amine solution or split-phase rich amine solution;
the rich amine solution generated by the primary absorption tower or the rich amine solution obtained after the split-phase rich amine solution generated by the primary absorption tower is separated is conveyed to a desorption device for analysis, so that lean amine solution and carbon dioxide are obtained;
optionally, cooling the rich amine solution or the split-phase rich amine solution generated by the secondary absorption tower through a circulating cooling assembly and then conveying the rich amine solution back to the secondary absorption tower;
and conveying the lean amine solution to the primary absorption tower and/or the secondary absorption tower, so that the lean amine solution continuously absorbs carbon dioxide and generates rich amine solution or split-phase rich amine solution.
[9] The method for capturing carbon dioxide according to the above [8], wherein after the secondary absorption tower is saturated in absorption, cooling by using a circulating cooling assembly is stopped, 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 to be analyzed, so that the lean amine solution and 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 flue gas and generates a phase-separated rich amine solution;
and separating the phase-separated rich amine solution generated in the first-stage absorption tower and/or the second-stage absorption tower by using a phase separator.
ADVANTAGEOUS EFFECTS OF INVENTION
The absorption device and the carbon dioxide trapping system can increase the gas-liquid residence time of the flue gas and the absorbent and promote the trapping efficiency of the absorption liquid on the carbon dioxide. And the absorption device and the carbon dioxide trapping system can reduce the volatilization amount of the organic amine on the premise of ensuring high-efficiency and low-cost trapping of carbon dioxide.
Furthermore, the carbon dioxide trapping method is simple and feasible, occupies a small space, and can realize large-batch carbon dioxide trapping.
Drawings
FIG. 1 shows a schematic view of an absorption device according to an embodiment of the invention;
FIG. 2 shows a schematic view of an absorption device according to another embodiment of the invention;
FIG. 3 shows a schematic diagram of a carbon dioxide capture system of one embodiment of the present invention;
FIG. 4 shows a schematic diagram of a carbon dioxide capture system of another embodiment of the present invention;
reference numerals illustrate:
1001: a first absorption tower; 1002: a second absorption tower; 1003. 1005: a condensing device;
1006. 1004: a spraying device; 1013: a recirculating cooling assembly;
1007. 1008, 1009, 1010, 1025, 1026: a valve;
1011. 1012, 1023: a power device; 1014. 1015: a condenser;
1022: a first-order phase separator; 1024: a two-stage phase separator; 1019: and a desorption device.
Detailed Description
Various exemplary embodiments, features and aspects of the invention are described in detail below. The word "exemplary" is used 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 illustration of the 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, well known methods, procedures, means, equipment and steps have not been described in detail so as not to obscure the present invention.
Unless otherwise indicated, all units used in the present invention are international standard units, and numerical values and numerical ranges appearing in the present invention should be understood to include systematic errors unavoidable in industrial production.
<First aspect>
As shown in fig. 1, a first aspect of the present invention is an absorption apparatus. The absorption apparatus includes a primary absorption column 1001, a secondary absorption column 1002, an optional circulation cooling unit 1013, and the like, and specifically, the absorption apparatus includes:
a primary absorption column 1001, wherein a primary absorbent can be introduced into the primary absorption column 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; the method comprises the steps of,
an optional recycle cooling assembly 1013, the recycle cooling assembly 1013 being coupled to the inside and/or outside of the secondary absorption tower 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 split-phase rich amine solution; and, in addition, the processing unit,
The circulation cooling unit 1013 can cool the rich amine solution or the split-phase rich amine solution generated in the secondary absorption tower 1002 and return the cooled rich amine solution to the secondary absorption tower 1002.
The carbon dioxide trapping system can increase the gas-liquid residence time of the flue gas and the absorbent and promote the trapping efficiency of the absorbent on the carbon dioxide. And moreover, the carbon dioxide trapping system can reduce the volatilization amount of the organic amine on the premise of ensuring 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 absorber inlet, and a rich amine solution outlet. The flue gas inlet is located at the bottom of the primary absorber 1001 in order to let the flue gas in. 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, and the flue gas flows from the flue gas inlet to the flue gas outlet. Thus, the flue gas flowing into the primary absorption tower 1001 is sufficiently brought into countercurrent contact with the primary absorbent, and carbon dioxide in the flue gas is absorbed by the primary absorbent, and becomes a rich amine solution or a split-phase 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 evacuation port, a secondary absorber inlet, and a rich amine solution outlet. The flue gas inlet is positioned at the bottom of the secondary absorption tower, so that the flue gas discharged from the flue gas outlet in the primary absorption tower 1001 flows into the secondary absorption tower 1002. The flue gas evacuation port is located at the top of the secondary absorber 1002 to evacuate the flue gas that eventually cannot be treated. In the secondary absorption tower 1002, the secondary absorbent flows from the secondary absorbent inlet to the bottom, and the flue gas flows from the flue gas inlet to the flue gas outlet. Thus, the flue gas flowing into the secondary absorption tower 1002 is sufficiently brought into countercurrent contact with the secondary absorbent, and carbon dioxide in the flue gas is absorbed by the secondary absorbent, and becomes a rich amine solution or a split-phase rich amine solution, and flows out from the rich amine solution outlet. The primary purpose of the secondary absorber 1002 of the present invention is to reduce the amount of entrained solvent in the flue gas while achieving decarbonization of the flue gas by a lower absorption temperature.
Further, in the present invention, the circulation cooling unit 1013 is connected to the inside and/or the outside of the secondary absorption tower 1002, wherein when the valve 1025 is opened, the circulation cooling unit 1013 can cool the rich amine solution generated in the secondary absorption tower 1002 or the split-phase rich amine solution by the power unit 1012 (e.g. pump, etc.), and then return to the secondary absorption tower 1002. The circulation cooling unit 1013 may be a circulation condenser in the present invention.
In some specific embodiments, the primary absorber 1001 has a volume V a The volume of the secondary absorption tower 1002 is V b The following relationship exists:
V a ≥2V b 。
when V is a ≥2V b In this case, the function of the secondary absorption tower 1002 can be most effectively exerted, so that the amount of the solvent entrained in the flue gas can be reduced while the decarbonization of the flue gas is realized through a lower absorption temperature.
Further, in the present invention, the saturated vapor pressure of the primary absorbent in the primary absorption column 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 The following relationship exists:
P a ≥P b 。
in the present invention, the higher the vapor pressure in the secondary absorption column 1002, the greater the solvent evaporation loss. By making the vapor pressure in the secondary absorption column 1002 smaller than that in the primary absorption column 1001, it is advantageous to reduce the solvent evaporation loss. In general, the means to achieve a low vapor pressure is to lower the temperature of the secondary absorber 1002 or to change the solvent composition. Since the temperature in the primary absorption column 1001 is different from the temperature in the secondary absorption column 1002, the difference in temperature is generally not considered when the saturated vapor pressure comparison is performed. For example, the temperature of the primary absorber 1001 may be 40 ℃, and the temperature of the secondary absorber 1002 may be 20 ℃, i.e.: saturated vapor pressure P of primary absorbent in primary absorption column 1001 measured at 40 c a Saturated vapor pressure P measured at 20℃with the secondary absorbent of the secondary absorption column 1002 b Presence of P a ≥P b Is a relationship of (3).
Further, the composition of the primary absorbent and/or the secondary absorbent is not particularly limited in the present invention, and may be an absorbent commonly used in the art. Specifically, the primary and/or secondary absorbent comprises an organic amine absorbent and/or a lean amine solution, preferably the organic amine absorbent comprises one or a combination of two or more of a non-phase change absorbent or a phase change absorbent.
As the organic amine absorbent, in the present invention, it may be a combination of one or more of Monoethanolamine (MEA), N-Methyldiethanolamine (MDEA), piperazine (PZ), isobutylamine (AMP), hydroxyethyl ethylenediamine (AEEA), diethylethanolamine (DEEA), and the like dissolved or diluted with a solvent.
The phase-change absorbent may be one of a composite organic amine phase-change absorbent, a phase-change absorbent composed of an organic amine absorbent and a phase-change absorbent, and a phase-change absorbent composed of a composite organic amine and an ionic liquid, and has a property of layering according to the concentration of carbon dioxide after absorbing carbon dioxide.
The composite organic amine phase change absorbent refers to an absorbent compounded by adding other weak polar solvents after mixing one or more organic amines with water, wherein the absorbent does not absorb CO 2 Before, the solvent is homogeneous and absorbs CO 2 Thereafter, the produced carbamate and the like are separated from the weak polar solvent, forming a lean phase and a rich phase. The phase change solvent is different from the conventional compound amine solvent in that the phase change solvent accounts for more than 30wt% and less than 50wt% of the weak polar solvent.
The lean amine solution may be a lean amine solution obtained by analyzing the rich amine solution in the analyzing column 1019, or may be a lean amine solution which is left after separating the rich amine solution by the phase separators 1022 and 1024.
In some specific embodiments, as shown in fig. 2, when the primary absorber and/or the secondary absorber comprises a phase change absorber, a phase separator 1022, 1024 is further disposed outside the primary absorber 1001 and/or the secondary absorber 1002, and the phase separator 1022, 1024 is used to separate the phase-separated rich amine solution generated in the primary absorber 1001 and/or the secondary absorber 1002.
For example, when using the composition of an organic amine absorbent, a split-phase absorbent and water as the organic amine absorbent When the absorbent is used, the organic amine can react with CO in the flue gas 2 The reaction generates carbamate salt, and the separation of the carbamate salt and water can be realized through the phase-splitting agent. After separation, the resulting rich amine solution is typically a carbamate salt, a small amount of unreacted organic amine, and the lean amine solution is an organic phase-splitting agent, water, and a small amount of unreacted organic amine.
The phase separators 1022, 1024 are means for layering the resulting phase separated rich amine solution. The phase splitters 1022, 1024 include a split-phase rich solution inlet at the top, a rich solution outlet at the bottom rich region, and a lean solution outlet at the upper lean region. Because 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 delivered to the resolving tower 1019 for resolving by the power device (e.g. pump etc.) 1011, and the lean amine solution can be delivered to the primary absorption tower 1001 and/or the secondary absorption tower 1002 after being mixed with the lean amine solution resolved by the power device (e.g. pump etc.) 1023 and the resolving tower 1019.
In some specific embodiments, the primary absorber 1001 comprises: spray assembly 1006, condensing unit 1003 and at least one filler layer; wherein,
the spray assembly 1006 and the condensing unit 1003 are located at the top of the primary absorber 1001;
the packing layer is located in the middle of the primary absorber 1001.
Further, the secondary absorption tower 1002 includes: spray assembly 1004, condensing unit 1005, and at least one filler layer; wherein,
the spray assembly 1004 and the condensing unit 1005 are located at the top of the secondary absorption column 1002;
the packing layer is located in the middle of the secondary absorber 1002.
The number of packing layers in the primary absorption tower 1001 and the secondary absorption tower 1002 is not particularly limited, and may be set as required.
<Second aspect>
As shown in fig. 3 and 4, a second aspect of the present invention provides a carbon dioxide capture system comprising: an absorption and desorption device 1019 according to any one of the first aspects of the present invention, the desorption device 1019 being configured to resolve a 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.
<Third aspect of the invention>
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:
delivering the flue gas to an absorber device comprising a primary absorber 1001 and a secondary absorber 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;
the rich amine solution generated by the primary absorption tower 1001 or the rich amine solution obtained after the phase-separated rich amine solution generated by the primary absorption tower 1001 is separated is conveyed to a desorption device 1019 for analysis through a power device 1011 to obtain lean amine solution and carbon dioxide;
optionally, the rich amine solution or the split-phase rich amine solution generated in the secondary absorption tower 1002 is returned to the secondary absorption tower 1002 after being cooled by the circulating cooling assembly 1013;
the lean amine solution is sent to the primary absorber 1001 and/or the secondary absorber 1002, allowing the lean amine solution to continue to absorb carbon dioxide and produce a rich amine solution or a split-phase rich amine solution.
Further, in some specific embodiments, after the secondary absorption tower 1002 is saturated, the cooling by the circulation cooling unit 1013 is stopped, and the rich amine solution generated by the secondary absorption tower 1002 or the rich amine solution obtained by separating the split-phase rich amine solution generated by the secondary absorption tower 1002 is sent to the desorption device 1019 through the power device 1011 to be resolved, so as to obtain the lean amine solution and carbon dioxide.
In the present invention, the purpose of cooling by using the circulation cooling unit 1013 is to cool down the flue gas CO in the secondary absorption tower 1002 2 The concentration is low, the absorption efficiency of the absorbent is reduced, the rich amine solution or the split-phase rich amine solution after primary absorption is less, the subsequent desorption and regeneration are difficult, and the absorption-regeneration efficiency of the whole process is reduced. The organic amine can be fully reacted with CO by cyclic absorption using the cooling down of the cyclic cooling assembly 1013 2 And the reaction improves the utilization efficiency of the absorbent.
For the use of the circulation cooling component 1013, the valves 1009 and 1026 may be disposed on the pipes of the second-stage absorption tower 1002 and the resolving tower 1019, when the circulation cooling component 1013 is used for cooling, the valves 1009 and 1026 may be closed, so that the rich amine solution or the split-phase rich amine solution generated in the first-stage absorption tower 1001 is cooled by the power device 1012 through the circulation cooling component 1013 and then is conveyed back to the second-stage absorption tower 1002, after the second-stage absorption tower 1002 is basically adsorbed and saturated, the valves 1009 and 1026 are opened, and the obtained rich amine solution or split-phase rich amine solution is conveyed to the next process.
The method of determining the absorption saturation is not particularly limited, and may be based on CO 2 The balance load is determined, when CO 2 The balance load reaches 0.40 to 0.50mol CO 2 A secondary absorbent per mole (40 ℃ C.) is considered to be saturated in its absorption.
Further, the primary absorption column 1001 and the secondary absorption column 1002 may be performed asynchronously. Specifically, the rich amine solution or the layered rich amine solution in the secondary absorption tower 1002 is circulated by the circulation cooling unit 1013 when the CO of the rich amine solution or the layered rich amine solution in the secondary absorption tower 1002 2 The balance load reaches 0.40 to 0.50mol CO 2 When/mol of the secondary absorbent (40 ℃), the valves 1009, 1026 on the passage of the secondary absorption tower 1002 for delivering the rich amine solution or the rich amine solution obtained by separating the split-phase rich amine solution generated in the secondary absorption tower 1002 to the desorption tower 1019 are opened, and the valve 1010 on the passage of the lean amine solution of the desorption device 1019 to the secondary absorption tower 1002 is opened. Then, the valve 1007 on the passage of the rich amine solution in the primary absorption column 1001 or the rich amine solution obtained by separating the phase-separated rich amine solution generated in the primary absorption column 1001 to the desorption device is closed, and the valve 1008 on the passage of the lean amine solution of the desorption device 1019 to the primary absorption column 1001 is closed.
When CO 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/mol of the secondary absorbent (40 ℃), the valves 1009 and 1026 on the passage of the desorption device 1019 for conveying the rich amine solution in the secondary absorption tower 1002 or the rich amine solution obtained by separating the split-phase rich amine solution generated by the secondary absorption tower 1002 are closed, and the valve 1010 on the passage of the desorption device 1019 for conveying the lean amine solution to the secondary absorption tower 1002 is closed; and the valve 1007 on the passage of the rich amine solution in the primary absorption tower 1001 or the rich amine solution obtained by separating the split-phase rich amine solution generated in the secondary absorption tower 1002 to the desorption device 1019 is opened, and the valve 1008 on the passage of the lean amine solution of the desorption device 1019 to the primary absorption tower 1001 is opened. The maximization of solvent absorption efficiency can be achieved by controlling the flow timing using a valve, and the primary absorbent and the secondary absorbent in the primary absorption tower 1001 and the secondary absorption tower 1002 can be recycled, thereby achieving maximization of process efficiency.
Specifically, in some specific embodiments, where the primary absorbent and the secondary absorbent are the same or different, but are both non-phase change absorbents, the specific method of implementation is:
The coal-fired or gas-fired flue 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. The primary absorber 1001 is filled with a primary absorbent, the secondary absorber 1002 is filled with a secondary absorbent, and the primary absorbent and the secondary absorbent absorb carbon dioxide in the flue gas in the primary absorber 1001 and the secondary absorber 1002 to generate a rich amine solution.
The rich amine solution generated in the primary absorption tower 1001 enters a subsequent desorption device 1019 for desorption, and lean amine solution and carbon dioxide are obtained. The desorbed lean amine solution is condensed by the condensers 1014, 1015 and then returned to the corresponding primary absorption tower 1001 and/or secondary absorption tower 1002, respectively, to form a circulating carbon dioxide capturing path.
The rich amine solution generated by the secondary absorption tower 1002 is cooled under the action of the circulating cooling assembly 1013 and then is conveyed to the secondary absorption tower 1002. After the secondary absorption tower 1002 is saturated, cooling by using the circulation cooling assembly 1013 is stopped, and the rich amine solution generated by the secondary absorption tower 1002 is conveyed to the desorption device 1019 for analysis by the power device, so as to obtain the lean amine solution and carbon dioxide. The desorbed lean amine solution is condensed by the condensers 1014, 1015 and then returned to the corresponding primary absorption tower 1001 and/or secondary absorption tower 1002, respectively, to form a circulating carbon dioxide capturing path.
In other specific embodiments, the primary and secondary absorbents are the same or different, and when the primary and/or secondary absorbents used comprise a phase-change absorbent, the primary and/or secondary absorbents absorb carbon dioxide in the flue gas and produce a split-phase rich amine solution; the split-phase rich amine solution produced in the primary absorption column 1001 and/or the secondary absorption column 1002 is separated by the phase splitters 1022, 1024.
The specific implementation method comprises the following steps: the coal-fired or gas-fired flue 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. A primary absorbent is introduced into the primary absorption tower 1001, a secondary absorbent is introduced into the secondary absorption tower 1002, and the primary absorbent and/or the secondary absorbent absorb carbon dioxide in the flue gas in the primary absorption tower 1001 and/or the secondary absorption tower 1002 and generate a split-phase rich amine solution. The split-phase rich amine solution generated by the secondary absorption tower 1002 is cooled under the action of the circulating cooling assembly 1013 and then is conveyed to the secondary absorption tower 1002. The split-phase rich amine solution produced by the primary absorption column 1001 and/or the secondary absorption column 1002 is separated by the phase splitters 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 in the primary absorption column 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 after desorption by the desorption device 1019 may be mixed and condensed by the condensers 1014, 1015 and delivered to the first absorption column 1001 and/or the second absorption column 1002.
The rich amine solution generated by the secondary absorption tower 1002 is cooled under the action of the circulating cooling assembly 1013 and then is conveyed to the secondary absorption tower 1002. After the secondary absorption tower 1002 is saturated, cooling by using the circulation cooling assembly 1013 is stopped, and the rich amine solution generated by the secondary absorption tower 1002 is conveyed to the desorption device 1019 for analysis by the power device, so as to obtain the lean amine solution and carbon dioxide. The desorbed lean amine solution is condensed by the condensers 1014, 1015 and then returned to the corresponding primary absorption tower 1001 and/or secondary absorption tower 1002, respectively, to form a circulating carbon dioxide capturing path.
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 the primary absorbent and the secondary absorbent absorb carbon dioxide in the flue gas in the primary absorption tower 1001 and the secondary absorption tower 1002 to generate a rich amine solution. The rich amine solution generated in the primary absorption tower 1001 is transported to a desorption device 1019 for desorption by a power device, and lean amine solution and carbon dioxide are obtained. The desorbed lean amine solution is condensed by the condensers 1014, 1015 and then returned to the corresponding primary absorption tower 1001 and/or secondary absorption tower 1002, respectively, to form a circulating carbon dioxide capturing path.
The split-phase rich amine solution generated by the secondary absorption tower 1002 is cooled under the action of the circulating cooling assembly 1013 and then is conveyed to the secondary absorption tower 1002. After the secondary absorption tower 1002 is saturated, cooling by using the circulation cooling assembly 1013 is stopped, and the split-phase rich amine solution generated in the secondary absorption tower 1002 is separated 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 for desorption, and the lean amine solution and carbon dioxide are obtained. The lean amine solution separated by the secondary phase separator 1024 and the lean amine solution desorbed by the desorption device 1019 are condensed by the condensers 1014, 1015 and then returned to the corresponding primary absorption tower 1001 and/or secondary absorption tower 1002, respectively, to form a circulating carbon dioxide capturing path.
When both the primary and secondary absorbents are phase-change absorbents, the phase-separated rich amine solution produced in the primary absorption column 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 after desorption by the desorption device 1019 may be mixed and condensed by the condensers 1014, 1015 and delivered to the first absorption column 1001 and/or the second absorption column 1002.
The split-phase rich amine solution generated by the secondary absorption tower 1002 is cooled under the action of the circulating cooling assembly 1013 and then is conveyed to the secondary absorption tower 1002. After the secondary absorption tower 1002 is saturated, cooling by using the circulation cooling assembly 1013 is stopped, and the split-phase rich amine solution generated by the secondary absorption tower 1002 is separated 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 for desorption, and the lean amine solution and carbon dioxide are obtained. The lean amine solution separated by the secondary phase separator 1024 and the lean amine solution desorbed by the desorption device 1019 are condensed by the condensers 1014, 1015 and then returned to the corresponding primary absorption tower 1001 and/or secondary absorption tower 1002, respectively, to form a circulating carbon dioxide capturing path.
Examples
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
In embodiments, the amount of primary absorbent is determined by the gas-liquid ratio, which is generally controlled between 200 and 300, such as 120000Nm for gas throughput 3 And/h, the primary absorbent is used in an amount of from 400 to 600 m 3 /h。
Example 1
In this example 1, a Monoethanolamine (MEA) solution having a mass concentration of 30% was used as the primary absorber and the secondary absorber for the primary absorber and the secondary absorber. The coal-fired or gas-fired flue gas after desulfurization, denitrification and dust removal passes through the first-stage absorption tower and is conveyed to the second-stage absorption tower through a flue gas pipeline. A30% Monoethanolamine (MEA) solution was introduced into the primary absorber, and a 30% Monoethanolamine (MEA) solution was introduced into the secondary absorber. In the primary absorption tower and the secondary absorption tower, the Monoethanolamine (MEA) solution and the Monoethanolamine (MEA) solution absorb carbon dioxide in the flue gas and generate rich amine solution.
The volume of the primary absorption tower is more than 2 times of that of the secondary absorption tower, more than 2 layers of fillers are arranged in the primary absorption tower, and more than 1 layer of fillers are arranged in the secondary absorption tower. The first-stage absorption tower and the second-stage absorption tower top comprise a spraying device and a condensing device, a 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 conveyed to the second-stage absorption tower after being cooled, because the rich amine solution CO in the second-stage absorption tower 2 The equilibrium load does not reach 0.40mol CO 2 And (3) adding the rich amine solution in the primary absorption tower into a subsequent analysis tower for regeneration at 40 ℃. And (3) allowing the rich amine solution generated in the first-stage absorption tower to enter a subsequent desorption device for regeneration, condensing the desorbed lean amine solution through a condenser, and respectively returning to the corresponding first-stage absorption tower.
Wherein, in the first-stage absorption tower: the saturated vapor pressure (40 ℃) of the Monoethanolamine (MEA) solution was 5.22kPa; in the secondary absorption column, the saturated vapor pressure (20 ℃) of the Monoethanolamine (MEA) solution was 1.65kPa.
Example 2
In this example 2, a Monoethanolamine (MEA) solution with a mass concentration of 30% was used as the primary absorbent in the primary absorption column, and a 30% n-Methyldiethanolamine (MDEA) solution with a mass concentration of 30% was used as the secondary absorbent in the secondary absorption column. The coal-fired or gas-fired flue gas after desulfurization, denitrification and dust removal passes through the first-stage absorption tower and is conveyed to the second-stage absorption tower through a flue gas pipeline. A30% by mass solution of Monoethanolamine (MEA) was fed to the primary absorber, and a 30% by mass solution of N-Methyldiethanolamine (MDEA) was fed to the secondary absorber. 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 rich amine solution.
The volume of the primary absorption tower is more than 2 times of that of the secondary absorption tower, more than 2 layers of fillers are arranged in the primary absorption tower, and more than 1 layer of fillers are arranged in the secondary absorption tower. The first-stage absorption tower and the second-stage absorption tower top 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 conveyed to the second-stage absorption tower after being cooled. And (3) simultaneously feeding the rich amine solution of the first-stage absorption tower into a subsequent desorption device for regeneration, and conveying the desorbed lean amine solution to the first-stage absorption tower through a metering pump. The valve on the channel of the secondary absorption tower, through which the rich amine solution is delivered to the desorption device, is closed, and the valve on the channel of the desorption device, through which the lean amine solution is delivered to the secondary absorption tower, is closed.
The rich amine solution in the secondary absorption tower circulates through a pump and a circulating condenser, and when the rich amine solution CO in the secondary absorption tower 2 The balance load reaches 0.40 to 0.50mol CO 2 At/mol of secondary absorbent (40 ℃), the valve on the passage of the rich amine solution in the secondary absorption tower to the desorption device is opened, and the valve on the passage of the lean amine solution in the desorption device to the secondary absorption tower is opened. Then, a valve on a passage for delivering the rich amine solution to the desorption apparatus in the primary absorption tower is closed, and the desorption apparatus is lean The valve on the passage of the amine solution to the primary absorber is closed. When rich amine solution CO in the secondary absorption tower 2 The balance load is reduced to 0.05-0.10mol CO 2 The valve on the channel of the rich amine solution in the secondary absorption tower for conveying to the desorption device is closed, and the valve on the channel of the lean amine solution in the desorption device for conveying to the secondary absorption tower is closed; and a valve on a channel for conveying the rich amine solution to the desorption device in the primary absorption tower is opened, and a valve on a 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: the saturated vapor pressure (40 ℃) of the Monoethanolamine (MEA) solution was 5.22kPa; in the secondary absorption column, the saturated vapor pressure (20 ℃) of the N-Methyldiethanolamine (MDEA) solution was 1.64kPa.
Example 3
In this example 3, a mixed solution of Monoethanolamine (MEA) and N-Methyldiethanolamine (MDEA) was used as the primary absorbent in the primary absorption tower. In this primary absorbent, the mass concentration of Monoethanolamine (MEA) was 30%, and the mass concentration of N-Methyldiethanolamine (MDEA) was 30%, which was designated as: 30% MEA/30% MDEA; the secondary absorber used a 30% strength by mass solution of N-Methyldiethanolamine (MDEA) as the secondary absorber. The coal-fired or gas-fired flue gas after desulfurization, denitrification and dust removal passes through the first-stage absorption tower and is conveyed to the second-stage absorption tower through a flue gas pipeline. 30% MEA/30% MDEA was fed to the primary absorber and 30% N-Methyldiethanolamine (MDEA) solution was fed to the secondary absorber. In the primary and secondary absorber columns, a 30% MEA/30% MDEA and 30% N-Methyldiethanolamine (MDEA) solution absorbs carbon dioxide in the flue gas and produces a rich amine solution.
The volume of the primary absorption tower is more than 2 times of that of the secondary absorption tower, more than 2 layers of fillers are arranged in the primary absorption tower, and more than 1 layer of fillers are arranged in the secondary absorption tower. The first-stage absorption tower and the second-stage absorption tower top 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 conveyed to the second-stage absorption tower after being cooled. And (3) simultaneously feeding the rich amine solution of the first-stage absorption tower into a subsequent desorption device for regeneration, and respectively returning the desorbed lean amine solution to the corresponding first-stage absorption tower through a metering pump. The valve on the channel of the secondary absorption tower, through which the rich amine solution is delivered to the desorption device, is closed, and the valve on the channel of the desorption device, through which the lean amine solution is delivered to the secondary absorption tower, is closed.
The rich amine solution in the secondary absorption tower circulates through a pump and a circulating condenser, and when the rich amine solution CO in the secondary absorption tower 2 The balance load reaches 0.40 to 0.50mol CO 2 At/mol of secondary absorbent (40 ℃), the valve on the passage of the rich amine solution in the secondary absorption tower to the desorption device is opened, and the valve on the passage of the lean amine solution in the desorption device to the secondary absorption tower is opened. Then, a valve on a passage of the rich amine solution in the primary absorption tower to the desorption device is closed, and a valve on a passage of the lean amine solution in the desorption device to the primary absorption tower is closed. When rich amine solution CO in the secondary absorption tower 2 The balance load is reduced to 0.05-0.10mol CO 2 The valve on the channel of the rich amine solution in the secondary absorption tower for conveying to the desorption device is closed, and the valve on the channel of the lean amine solution in the desorption device for conveying to the secondary absorption tower is closed; and a valve on a channel for conveying the rich amine solution to the desorption device in the primary absorption tower is opened, and a valve on a 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: the saturated vapor pressure (40 ℃) of the Monoethanolamine (MEA)/N-Methyldiethanolamine (MDEA) solution was 3.00kPa; in the secondary absorption column, the saturated vapor pressure (20 ℃) of the N-Methyldiethanolamine (MDEA) solution was 1.64kPa.
Example 4
In this example 4, the primary absorption tower uses a mixed solution of Monoethanolamine (MEA) and isobutolamine (AMP) as the primary absorbent. In this primary absorbent, the mass concentration of Monoethanolamine (MEA) was 30% and the mass concentration was 30%, and was noted as: 30% MEA/30% AMP; the secondary absorption tower uses a mixed solution of Piperazine (PZ) and isobutolamine (AMP) as a secondary absorbent. In this secondary absorbent, the mass concentration of Piperazine (PZ) was 30%, and the mass concentration of isobutolamine (AMP) was 30%, which is expressed as: 30% PZ/30% AMP. The coal-fired or gas-fired flue gas after desulfurization, denitrification and dust removal passes through the first-stage absorption tower and is conveyed to the second-stage absorption tower through a flue gas pipeline. 30% AMP/30% MDEA was fed to the primary absorber and 30% PZ/30% AMP was fed to the secondary absorber. In the primary and secondary absorption towers, 30% AMP/30% MDEA and 30% PZ/30% AMP absorb carbon dioxide in the flue gas and produce a rich amine solution.
The volume of the primary absorption tower is more than 2 times of that of the secondary absorption tower, more than 2 layers of fillers are arranged in the primary absorption tower, and more than 1 layer of fillers are arranged in the secondary absorption tower. The first-stage absorption tower and the second-stage absorption tower top 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 conveyed to the second-stage absorption tower after being cooled. And (3) simultaneously feeding the rich amine solution of the first-stage absorption tower into a subsequent desorption device for regeneration, and conveying the desorbed lean amine solution to the first-stage absorption tower through a metering pump. The valve on the channel of the secondary absorption tower, through which the rich amine solution is delivered to the desorption device, is closed, and the valve on the channel of the desorption device, through which the lean amine solution is delivered to the secondary absorption tower, is closed.
The rich amine solution in the secondary absorption tower circulates through a pump and a circulating condenser, and when the rich amine solution CO in the secondary absorption tower 2 The balance load reaches 0.40 to 0.50mol CO 2 At/mol of secondary absorbent (40 ℃), the valve on the passage of the rich amine solution in the secondary absorption tower to the desorption device is opened, and the valve on the passage of the lean amine solution in the desorption device to the secondary absorption tower is opened. Then, a valve on a passage of the rich amine solution in the primary absorption tower to the desorption device is closed, and a valve on a passage of the lean amine solution in the desorption device to the primary absorption tower is closed. When rich amine solution CO in the secondary absorption tower 2 The balance load is reduced to 0.05-0.10mol CO 2 The valve on the channel of the rich amine solution in the secondary absorption tower for conveying to the desorption device is closed, and the valve on the channel of the lean amine solution in the desorption device for conveying to the secondary absorption tower is closed; and a valve on a channel for conveying the rich amine solution to the desorption device in the primary absorption tower is opened,and a valve on a channel for delivering the lean amine solution of the desorption device to the primary absorption tower is opened.
Wherein, in the first-stage absorption tower: the saturated vapor pressure (40 ℃) of the 30% MEA/30% AMP solution was 3.00kPa; in the secondary absorption column, the saturated vapor pressure (20 ℃) of the 30% PZ/30% AMP solution was 1.05kPa.
Example 5
In this example 5, a mixed solution of Monoethanolamine (MEA) and Diethylethanolamine (DEEA) was used as the primary absorbent in the primary absorption column. In this primary absorbent, the mass concentration of Monoethanolamine (MEA) was 30% and the mass concentration of Diethylethanolamine (DEEA) was 30%, which is described as: 30% MEA/30% DEEA; the secondary absorber used a 30% strength by mass Diethylethanolamine (DEEA) solution as the secondary absorber. 30% MEA/30% DEEA was fed to the primary absorber and 30% Diethylethanolamine (DEEA) solution was fed to the secondary absorber. The coal-fired or gas-fired flue gas after desulfurization, denitrification and dust removal passes through the first-stage absorption tower and is conveyed to the second-stage absorption tower through a flue gas pipeline. In the primary absorber, 30% AMP/30% MDEA absorbs carbon dioxide in the flue gas and generates 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 primary absorption tower is more than 2 times of that of the secondary absorption tower, more than 2 layers of fillers are arranged in the primary absorption tower, and more than 1 layer of fillers are arranged in the secondary absorption tower. The tower tops of the first-stage absorption tower and the second-stage absorption tower comprise a spraying device and a condensing device, and a first-stage phase separator is arranged at the tower bottom of the first-stage absorption tower and is used for separating the phase-separated rich amine solution generated by the first-stage absorption tower so as to obtain rich amine solution and lean amine solution. The circulating condenser is connected to the outside of the secondary absorption tower, and the rich amine solution generated by the secondary absorption tower is conveyed to the secondary absorption tower after being cooled. 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 being resolved by the desorption device and conveyed to the first-stage absorption tower through the metering pump, the valve on the channel of the rich amine solution in the second-stage absorption tower for conveying to the desorption device is closed, and the valve on the channel of the lean amine solution of the desorption device for conveying to the second-stage absorption tower is closed.
The rich amine solution in the secondary absorption tower circulates through a pump and a circulating condenser, and when the rich amine solution CO in the secondary absorption tower 2 The balance load reaches 0.40 to 0.50mol CO 2 At/mol of secondary absorbent (40 ℃), the valve on the passage of the rich amine solution in the secondary absorption tower to the desorption device is opened, and the valve on the passage of the lean amine solution in the desorption device to the secondary absorption tower is opened. Then, the valve on the passage of the rich amine solution in the first-stage 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-stage absorption tower is closed. When rich amine solution CO in the secondary absorption tower 2 The balance load is reduced to 0.05-0.10mol CO 2 The valve on the channel of the rich amine solution in the secondary absorption tower for conveying to the desorption device is closed, and the valve on the channel of the lean amine solution in the desorption device for conveying to the secondary absorption tower is closed; and a valve on a channel for conveying the rich amine solution to the desorption device in the first-stage phase separator is opened, and a valve on a 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 ℃) of the 30% MEA/30% DEEA solution was 3.18kPa; in the secondary absorption column, the saturated vapor pressure (20 ℃) of the 30% DEEA solution was 2.47kPa.
Example 6
In this example 6, a mixed solution of Monoethanolamine (MEA) and Diethylethanolamine (DEEA) was used as the primary absorbent in the primary absorption column. In this primary absorbent, the mass concentration of Monoethanolamine (MEA) was 30% and the mass concentration of Diethylethanolamine (DEEA) was 30%, which is described as: 30% MEA/30% DEEA; the secondary absorption tower uses a mixed solution of hydroxyethylethylene diamine (AEEA) and Diethylethanolamine (DEEA) as a secondary absorbent. In the secondary absorbent, the mass concentration of hydroxyethyl ethylenediamine (AEEA) was 30%, and the mass concentration of diethyl ethanolamine (DEEA) was 30%, which was recorded as: 30% AEEA/30% DEEA. 30% MEA/30% DEEA was fed to the primary absorber and 30% AEEA/30% DEEA was fed to the secondary absorber. The coal-fired or gas-fired flue gas after desulfurization, denitrification and dust removal passes through the first-stage absorption tower and is conveyed to the second-stage absorption tower through a flue gas pipeline. In 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 absorber, 30% MEA/30% DEEA absorbs carbon dioxide from the flue gas and produces a split-phase rich amine solution.
The volume of the primary absorption tower is more than 2 times of that of the secondary absorption tower, more than 2 layers of fillers are arranged in the primary absorption tower, and more than 1 layer of fillers are arranged in the secondary absorption tower. The tower bottoms of the first-stage absorption tower and the second-stage absorption tower are respectively provided with a first-stage phase separator and a second-stage phase separator, the first-stage phase separator is used for separating the phase-separated rich amine solution generated by the first-stage absorption tower to obtain rich amine solution and lean amine solution, and the second-stage phase separator is used for separating the phase-separated rich amine solution generated by the second-stage absorption tower to obtain rich amine solution and lean amine solution. 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 conveyed to the secondary absorption tower after being cooled.
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 being resolved by the desorption device and conveyed to the first-stage absorption tower through the metering pump, the valve on the channel of the rich amine solution in the second-stage absorption tower for conveying to the desorption device is closed, and the valve on the channel of the lean amine solution of the desorption device for conveying to the second-stage absorption tower is closed. The split-phase rich amine solution in the secondary absorption tower circulates through a pump and a circulating condenser, and when the split-phase rich amine solution CO in the secondary absorption tower 2 The balance load reaches 0.40 to 0.50mol CO 2 And separating the split-phase rich amine solution in the secondary absorption tower by a secondary phase separator at the temperature of/mol of the secondary absorbent (40 ℃) to obtain rich amine solution and lean amine solution.
The valve on the passage of the rich amine solution of the secondary phase separator to the desorption device is opened, and the valve on the passage of the lean amine solution of the desorption device to the secondary absorption tower is opened. Then, the rich amine solution in the first-stage phase separator is delivered to a desorption deviceThe valve on the line is closed and the valve on the path of the lean amine solution from the desorber to the primary absorber is closed. Phase-separated rich amine solution CO in secondary absorption tower 2 The balance load is reduced to 0.05-0.10mol CO 2 The valve on the channel of the rich amine solution in the secondary phase separator for conveying to the desorption device is closed, and the valve on the channel of the lean amine solution in the desorption device for conveying to the secondary absorption tower is closed; the valves on the channels of the primary phase separator where the rich amine solution is delivered to the desorber are opened and the valves on the channels of the desorber where the lean amine solution is delivered to the primary absorber are opened.
Wherein, in the first-stage absorption tower: the saturated vapor pressure (40 ℃) of the 30% MEA/30% DEEA solution was 3.18kPa; in the secondary absorption column, the saturated vapor pressure (20 ℃) of the 30% MEA/30% AEEA solution was 0.95kPa.
The above examples of the present invention are merely illustrative of the present invention and are not intended to limit the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.

Claims (9)

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 pipe connecting the primary absorption tower and the secondary absorption tower; the method comprises the steps of,
a circulating cooling assembly connected to the inside and/or the outside of the secondary absorption tower, 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 rich amine solution or split-phase rich amine solution; and, in addition, the processing unit,
The circulating cooling component can cool the rich amine solution generated by the secondary absorption tower or the split-phase rich amine solution and then convey the rich amine solution back to the secondary absorption tower;
let the volume of the primary absorption tower be V a The volume of the secondary absorption tower is V b The following relationship exists:
V a ≥2V b ；
setting the saturated vapor pressure of the primary absorbent in the primary absorption tower at 20-40 ℃ as P a The saturated vapor pressure of the secondary absorbent in the secondary absorption tower at 20-40 ℃ is P b The following relationship exists:
P a ≥P b 。
2. the absorption device according to claim 1 wherein the primary and/or secondary absorbent comprises an organic amine absorbent and/or a lean amine solution.
3. The absorber of claim 2 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.
4. An absorption unit according to any one of claims 1-3, wherein when the primary and/or secondary absorbent comprises a phase change absorbent, a phase separator is further provided outside the primary and/or secondary absorption tower for separating the phase separated rich amine solution produced by the primary and/or secondary absorption tower.
5. An absorption unit according to any one of claims 1-3, wherein the primary absorption tower and/or secondary absorption tower comprises: the device comprises a spraying assembly, a condensing device and at least one filler 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 primary absorption tower and/or the secondary absorption tower.
6. A carbon dioxide capture system, comprising: an absorption apparatus and a desorption apparatus as claimed in any one of claims 1 to 5 for resolving a 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.
7. A carbon dioxide capturing method characterized by capturing with the carbon dioxide capturing system according to claim 6, the capturing method comprising the steps of:
delivering the flue gas to an absorption device, wherein the absorption device comprises a primary absorption tower and a secondary absorption tower;
Introducing a primary absorbent into the primary absorption tower, and introducing a secondary absorbent into the secondary 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 rich amine solution or split-phase rich amine solution;
the rich amine solution generated by the primary absorption tower or the rich amine solution obtained after the split-phase rich amine solution generated by the primary absorption tower is separated is conveyed to a desorption device for analysis, so that lean amine solution and carbon dioxide are obtained;
the rich amine solution or the split-phase rich amine solution generated by the secondary absorption tower is conveyed back to the secondary absorption tower after being cooled by a circulating cooling assembly;
and conveying the lean amine solution to the primary absorption tower and/or the secondary absorption tower, so that the lean amine solution continuously absorbs carbon dioxide and generates rich amine solution or split-phase rich amine solution.
8. The method according to claim 7, wherein after the secondary absorption tower is saturated, cooling by using a circulation cooling assembly is stopped, 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 sent to a desorption device for analysis, so as to obtain the lean amine solution and carbon dioxide.
9. The carbon dioxide capture method of claim 7 or 8, wherein when a primary and/or secondary absorbent is used comprising a phase change absorbent, the primary and/or secondary absorbent absorbs carbon dioxide in the flue gas and produces a split-phase rich amine solution;
and separating the phase-separated rich amine solution generated in the first-stage absorption tower and/or the second-stage absorption tower by using a phase separator.
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