CN116059793A - System and method for wet capturing carbon dioxide - Google Patents

System and method for wet capturing carbon dioxide Download PDF

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Publication number
CN116059793A
CN116059793A CN202111271603.1A CN202111271603A CN116059793A CN 116059793 A CN116059793 A CN 116059793A CN 202111271603 A CN202111271603 A CN 202111271603A CN 116059793 A CN116059793 A CN 116059793A
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liquid
washing
gas
regeneration
zone
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CN202111271603.1A
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Chinese (zh)
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黄钟斌
陈曦
叶宁
郭本帅
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China Petroleum and Chemical Corp
Research Institute of Sinopec Nanjing Chemical Industry Co Ltd
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China Petroleum and Chemical Corp
Research Institute of Sinopec Nanjing Chemical Industry Co Ltd
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Priority to CN202111271603.1A priority Critical patent/CN116059793A/en
Publication of CN116059793A publication Critical patent/CN116059793A/en
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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
    • B01D53/1406—Multiple stage absorption
    • 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
    • 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
    • B01D53/1493—Selection of liquid materials for use as 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
    • B01D53/26—Drying gases or vapours
    • B01D53/265—Drying gases or vapours by refrigeration (condensation)
    • 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
    • B01D2252/10—Inorganic absorbents
    • B01D2252/103—Water
    • 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)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Gas Separation By Absorption (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention relates to the technical field of wet carbon dioxide capture, in particular to a system and a method for wet carbon dioxide capture, wherein the system comprises an absorption tower, the absorption tower comprises an absorption zone and a washing zone from bottom to top, and a washing tank is communicated with the bottom of the washing zone; the top end of the regeneration tower is communicated with the bottom end of the absorption zone through a first pipeline; the regeneration gas separator is communicated with the top end of the regeneration tower through a third pipeline; the underground groove is communicated with the bottom end of the regeneration gas separator; the bottom end of the regeneration gas separator is also communicated with the top end of the washing zone. According to the invention, the condensate in the regeneration gas separator is introduced into the regeneration tower as the absorption liquid, so that the purified gas can be further purified, the temperature of the purified gas is reduced, the amine escape is reduced, the amount of external washing liquid can be reduced, the internal circulation of water in the system is realized, and the water balance of the system is controlled stably.

Description

System and method for wet capturing carbon dioxide
Technical Field
The invention relates to the technical field of wet carbon dioxide capture, in particular to a system and a method for capturing carbon dioxide by a wet method.
Background
Currently wet technology has been perfecting and iterating for decades as the dominant technology to enable large scale carbon dioxide capture. Continuous optimization of trapping solvents such as organic amine, ionic liquid and amino acid salt, introduction of energy-saving processes such as heat pump and MVR flash evaporation, and improvement of mass transfer efficiency such as efficient filler and supergravity technology are thoroughly studied and made, and a set of efficient, energy-saving, environment-friendly and reliable trapping technology is formed on the whole.
By summarizing the practical driving conditions of a plurality of sets of ten-thousand-ton carbon dioxide trapping devices, the stable operation of the trapping system is considered, and the most important water balance control of the system is realized except the reasonable control of conventional process parameters such as temperature, flow and the like. Namely, the water quantity carried by the flue gas entering the absorption tower and the water quantity carried by the purified gas exiting the absorption tower reach an equilibrium state. Water balance control is a major factor affecting the concentration fluctuations of the absorbent, which in turn affect the trapping effect of the absorbent and the stability of the final system operation.
In the conventional carbon dioxide capturing process, deionized water is generally used as an initial washing liquid, and the total amount of the washing liquid and the concentration of amine (i.e., alkalinity) slowly rise (4-8 wt%) along with the circulation of the washing section, and the rise of the concentration of amine leads to the decrease of the washing effect, i.e., the increase of the absorbent content in the purified gas, thereby increasing the loss. In addition, aiming at the increase of the concentration of the amine, the washing liquid is usually required to be put into an underground tank, and then the desalted water is pumped into the underground tank to reduce the concentration of the washing liquid, so that the washing effect is ensured, and the liquid supplementing mode can cause obvious fluctuation of the temperature and the concentration of the absorbent in the regeneration tower; in addition, for the washing section of the purified gas outlet tower, the washing liquid is initially external demineralized water, and the temperature of the washing liquid is slowly increased along with the continuous circulation washing, a washing liquid cooler is required to be arranged, meanwhile, the concentration of the washing liquid is gradually increased to further influence the washing effect, the demineralized water is required to be added to the washing liquid at regular intervals to reduce the concentration of the washing liquid, and the external additional demineralized water is easy to damage the water balance in the system.
Disclosure of Invention
The invention aims to enhance the washing effect on amine liquid drops in purified gas, reduce the influence of the water supplementing process on the system temperature and concentration, and provide a system and a method for capturing carbon dioxide by a wet method.
In order to achieve the above object, according to a first aspect of the present invention, there is provided a system for capturing carbon dioxide by a wet process, the system comprising an absorption tower, the absorption tower comprising, from bottom to top, an absorption zone for contacting a feed gas containing carbon dioxide with an absorbent to react to obtain a pre-purified gas and an absorbent rich liquid, and a scrubbing zone for scrubbing the pre-purified gas to obtain a purified gas;
the washing tank is communicated with the bottom of the washing zone and is used for storing washing rich liquid obtained by washing;
the top end of the regeneration tower is communicated with the bottom end of the absorption zone through a first pipeline and is used for resolving the absorbent rich liquid to obtain regenerated gas and absorbent lean liquid, wherein the absorbent lean liquid is divided into lean liquid a and lean liquid b;
the regeneration gas separator is communicated with the top end of the regeneration tower through a third pipeline and is used for condensing the regenerated gas to obtain condensate and product gas, wherein the condensate is divided into cold liquid A and cold liquid B;
the underground tank is communicated with the bottom end of the regeneration gas separator and is used for storing the cold liquid A;
the bottom end of the regeneration gas separator is also communicated with the top end of the washing zone, and is used for introducing the cold liquid B into the washing zone to wash the pre-purified gas.
In a second aspect the invention provides a method of wet capturing carbon dioxide, carried out in a system as described in the first aspect.
According to the technical scheme, the condensate in the regenerated gas separator is introduced to serve as the purified gas washing liquid at the top of the absorption tower, and the alkalinity of the regenerated gas condensate is low (about 1 wt%) and is continuously supplemented to the washing liquid, so that the concentration of the amine in the washing liquid is basically maintained at a lower concentration (about 2 wt%) and a stable washing effect can be ensured, meanwhile, the addition of desalted water to the system is not required regularly, and the consumption of the desalted water is reduced; on the other hand, the washing liquid is continuously from the regenerated gas condensate, so that the lower temperature can be kept, and the use of a cooler is reduced; the method can also reduce the amount of external washing liquid, realize the internal circulation of water in the system, and is beneficial to stabilizing and controlling the water balance of the system.
Drawings
FIG. 1 is a schematic diagram of a system for wet capturing carbon dioxide according to an embodiment of the present invention;
fig. 2 is a schematic structural view of a system for capturing carbon dioxide by wet process in comparative example according to the present invention.
Description of the reference numerals
1. First pipeline 2, second pipeline
3. Third pipeline 10, absorption tower
20. Regeneration tower 11, lean solution cooler
12. Washing tank 13 and rich liquid pump
14. Lean liquid pump 21 and regenerated gas cooler
22. Boiler 23, underground tank
24. Regeneration gas separator 25 and heat exchanger
101. Absorption zone 102, washing zone
15. Detergent cooler
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
In the present invention, unless otherwise specified, terms such as "upper, lower, left, and right" and "upper, lower, left, and right" are used generically to refer to the upper, lower, left, and right illustrated in the drawings; "inner and outer" generally refer to the inner and outer relative to the contour of the components themselves; "distal" and "proximal" generally refer to the distance relative to the contour of the components themselves.
Fig. 1 is a schematic structural view of a system for capturing carbon dioxide by wet process according to an embodiment of the present invention, the present invention provides a system for capturing carbon dioxide by wet process, the system comprises an absorption tower 10, the absorption tower 10 comprises an absorption zone 101 and a washing zone 102 from bottom to top, the absorption zone 101 is used for contacting and reacting a raw gas containing carbon dioxide with an absorbent to obtain a pre-purified gas and an absorbent rich liquid, and the washing zone 102 is used for washing the pre-purified gas to obtain a purified gas;
a washing tank 12 which is communicated with the bottom of the washing zone 102 and is used for storing washing rich liquid obtained by washing;
a regeneration tower 20, wherein the top end of the regeneration tower 20 is communicated with the bottom end of the absorption zone 101 through a first pipeline 1, and a rich liquid pump 13 is arranged on the first pipeline 1 and is used for pumping the absorbent rich liquid into the regeneration tower 20 for analysis to obtain regenerated gas and absorbent lean liquid, wherein the absorbent lean liquid is divided into a lean liquid a and a lean liquid b;
a regeneration gas separator 24, which is communicated with the top end of the regeneration tower 20 through a third pipeline 3, and is used for condensing the regeneration gas to obtain condensate and product gas, wherein the condensate is divided into cold liquid A and cold liquid B;
an underground tank 23 communicated with the bottom end of the regeneration gas separator 24 for storing the cold liquid A;
the bottom end of the regeneration gas separator 24 is also in communication with the top end of the scrubbing zone 102 for introducing the cold liquid B into the scrubbing zone 102 for scrubbing the pre-purge gas.
In the invention, the effect of the cleaning solution is that the temperature of the purified gas can be reduced, the volatilization of the amine liquid vapor and the entrainment of liquid drops (collectively referred to as amine escape loss) can be reduced, the absorbent is an amine-containing solution, and the raw material gas containing carbon dioxide is contacted with the absorbent for reaction, so that a certain amount of amine is still contained in the pre-purified gas; the condensate separated by the regeneration gas separator 24 is divided into two paths (cold liquid a and cold liquid B), and cold night B is introduced into the washing zone 102 as a washing liquid, so that the pre-purified gas is washed, which has the following technical effects: 1. by washing the purified gas, the temperature of the pre-purified gas can be reduced, the amine content in the pre-purified gas can be reduced, and the amine escape can be reduced; 2. the use of a washing liquid cooler can be reduced due to the lower temperature of the condensate (30-40 ℃); 3. the condensate is generated in the system, so that water supplement can be reduced, water balance in the system is realized, and the stability of the concentration of the absorbent and the temperature of the system is facilitated to be maintained, thereby improving the capturing effect of the absorbent on carbon dioxide.
In some preferred embodiments of the present invention, preferably, the washing liquid is divided into washing liquid C and washing liquid D; wherein the bottom end of the washing tank 12 is communicated with the top end of the washing zone 102 through a pump, and is used for circularly introducing the washing liquid C into the absorption zone 102 to wash the pre-purified gas; further preferably, the bottom end of the washing tank 12 is in communication with the first line 1 for adding the washing liquid D to the absorbent rich liquid for post-treatment.
In some preferred embodiments of the present invention, the upper end of the absorption zone 101 is connected to the bottom end of the regeneration tower 20 through a second pipeline 2, and a lean liquid pump 14 is disposed on the second pipeline 2, so as to pump the lean liquid a into the absorption tower 10, and make reverse contact with the raw gas to perform the reaction.
According to the present invention, the system preferably further includes a heat exchanger 25 respectively connected to the first pipeline 1 and the second pipeline 2, for exchanging heat between the absorbent rich liquid and the lean liquid a, so as to realize comprehensive utilization of heat in the system.
According to the invention, the second line 2 is preferably provided with a lean liquor cooler 11 for cooling the lean liquor a.
In the present invention, preferably, the third pipeline 3 is provided with a regeneration gas cooler 21 for cooling the regeneration gas to obtain a cooling gas.
In the present invention, preferably, the system further comprises a boiler 22 communicating with the bottom of the regeneration tower 20 for supplying heat to the regeneration tower 20, and the heat source of the boiler 22 may be a heat source known to those skilled in the art that can be used to heat the boiler, for example, hot steam from a steam outer pipe.
In some preferred embodiments of the present invention, preferably, the bottom of the regeneration tower 20 communicates with the underground tank 23 for introducing the lean liquid b into the underground tank 23 for post-treatment.
In some preferred embodiments of the invention, the height of the regeneration gas separator 24 is greater than the height of the sink 12, thereby enabling condensate to fill the sink 12 solely by gravity.
In a second aspect the invention provides a method of wet capturing carbon dioxide, carried out in a system as described in the first aspect.
The method for capturing carbon dioxide by the wet method according to fig. 1 is as follows:
the raw material gas containing carbon dioxide (the carbon dioxide content is about 12.5 vol%) enters the absorption tower 10 from the bottom of the absorption zone 102, and is reversely contacted with the absorbent from the top of the absorption zone 102 to carry out absorption reaction, so as to obtain pre-purified gas and absorbent rich liquid;
the pre-purified gas continues to move upwards to enter a washing area 101, contacts with washing liquid to be washed, so as to obtain purified gas and washing rich liquid, and the purified gas is extracted through a gas outlet at the top of an absorption tower 10;
the absorbent rich liquid is introduced into the top of a regeneration tower 20 from the bottom of an absorption tower 10 through a first pipeline 1 provided with a rich liquid pump 13, a boiler 22 is arranged at the bottom of the regeneration tower 20 and is used for supplying heat to the regeneration tower 20, and the absorbent rich liquid rich in carbon dioxide is analyzed in the regeneration tower 20 at high temperature to obtain absorbent lean liquid and regenerated gas;
the adsorbent lean solution is divided into lean solution a and lean solution b, wherein lean solution a is introduced into the top of the absorption zone 101 and is circularly added into the adsorbent; the lean liquid b is introduced into the underground tank 23 for subsequent treatment;
the regenerated gas enters a third pipeline 3, is cooled by a regenerated gas cooler 23 and then is cooled by a regenerated gas separator 24 to obtain product gas and condensate, wherein the content of carbon dioxide in the product gas is more than 99 volume percent; the condensate is divided into a cold liquid A and a cold liquid B, wherein the cold liquid A enters an underground tank 23 for post-treatment, and the cold liquid B is introduced into the washing zone 102 and is used for washing the pre-purified gas;
the washing liquid rich liquid is divided into a washing liquid C and a washing liquid D, wherein the washing liquid C is circularly introduced into the absorption zone 102 to wash the pre-purified gas; and adding the washing liquid D into the absorbent rich liquid for post-treatment.
Example 1
Feeding a raw material gas containing carbon dioxide (the carbon dioxide content is 12.5 vol%) from the bottom of an absorption zone 102 into an absorption tower 10, and reversely contacting with an absorbent from the top of the absorption zone 102 to perform absorption reaction to obtain a pre-purified gas and an absorbent rich liquid;
the pre-purified gas continues to move upwards to enter a washing area 101, contacts with washing liquid to be washed, so as to obtain purified gas and washing rich liquid, and the purified gas is extracted through a gas outlet at the top of an absorption tower 10;
the absorbent rich liquid is introduced into the top of a regeneration tower 20 from the bottom of an absorption tower 10 through a first pipeline 1 provided with a rich liquid pump 13, a boiler 22 is arranged at the bottom of the regeneration tower 20 and is used for supplying heat to the regeneration tower 20, and the absorbent rich liquid rich in carbon dioxide is analyzed in the regeneration tower 20 at high temperature to obtain absorbent lean liquid and regenerated gas;
the adsorbent lean solution is divided into lean solution a and lean solution b, wherein lean solution a is introduced into the top of the absorption zone 101 and is circularly added into the adsorbent; the lean liquid b is introduced into the underground tank 23 for subsequent treatment;
the regenerated gas enters a third pipeline 3, is cooled by a regenerated gas cooler 23 and then is cooled by a regenerated gas separator 24 to obtain product gas and condensate (the concentration of amine is 1wt percent, the temperature is 35 ℃), wherein the carbon dioxide content in the product gas is 99.5 volume percent; the condensate is divided into a cold liquid A and a cold liquid B, wherein the cold liquid A enters an underground tank 23 for post-treatment, and the cold liquid B is introduced into the washing zone 102 and is used for washing the pre-purified gas;
the washing liquid rich liquid is divided into a washing liquid C and a washing liquid D, wherein the washing liquid C is circularly introduced into the absorption zone 102 to wash the pre-purified gas; adding the washing liquid D into the absorbent rich liquid for post-treatment;
in this example, the amine concentration in the wash liquor was maintained at substantially 2wt%.
Comparative example
CO using the apparatus shown in FIG. 2 2 The steps of trapping are as follows:
feeding a raw material gas containing carbon dioxide (the carbon dioxide content is 12.5 vol%) from the bottom of an absorption zone 102 into an absorption tower 10, and reversely contacting with an absorbent from the top of the absorption zone 102 to perform absorption reaction to obtain a pre-purified gas and an absorbent rich liquid;
the pre-purified gas continues to move upwards to enter a washing area 101, contacts with washing liquid to be washed, so as to obtain purified gas and washing rich liquid, and the purified gas is extracted through a gas outlet at the top of an absorption tower 10;
the absorbent rich liquid is introduced into the top of a regeneration tower 20 from the bottom of an absorption tower 10 through a first pipeline 1 provided with a rich liquid pump 13, a boiler 22 is arranged at the bottom of the regeneration tower 20 and is used for supplying heat to the regeneration tower 20, and the absorbent rich liquid rich in carbon dioxide is analyzed in the regeneration tower 20 at high temperature to obtain absorbent lean liquid and regenerated gas;
the adsorbent lean solution is divided into lean solution a and lean solution b, wherein lean solution a is introduced into the top of the absorption zone 101 and is circularly added into the adsorbent; the lean liquid b is introduced into the underground tank 23 for subsequent treatment;
the regenerated gas enters a third pipeline 3, is cooled by a regenerated gas cooler 23 and then is cooled by a regenerated gas separator 24 to obtain product gas and condensate (the concentration of amine is 1wt percent, the temperature is 35 ℃), wherein the carbon dioxide content in the product gas is 99.5 volume percent; condensate enters the underground tank 23;
the rich liquid of the washing liquid is circularly introduced into the absorption area 102 after being pressurized by a booster pump and cooled by a detergent cooler, the pre-purified gas is washed, when the concentration of the amine in the washing liquid reaches 6wt%, the washing liquid 15 is introduced into the underground tank 23, and desalted water is injected into the washing tank 12;
in this comparative example, the concentration of amine in the washing liquid fluctuates greatly, and the total amount of the washing liquid and the concentration (i.e., alkalinity) rise slowly (6 to 8 wt%) with the circulation of the washing section, and the rise in concentration results in a decrease in the washing effect, i.e., the absorbent content in the purge gas increases to increase the loss.
Experimental example
On existing industrial plants (CO 2 Capture scale of 3 ten thousand tons/year), CO in feed gas 2 The content is 12.5wt%, the absorbent is 20wt% monoethanolamine, and the device operates under the design working condition. For the washing section, the concentration of the amine in the washing liquid is respectively controlled to be 1wt%,2wt%,3wt%,4wt%,5wt% and 6wt%, and the content of the absorbent in the purified gas obtained under the corresponding concentration, namely the amine escape amount, is monitored and converted into capturing CO per ton 2 The results of the experiments are shown in table 1.
TABLE 1
Concentration of washing solution (wt%) 1 2 3 4 5 6
Amine escape loss (kg/t CO) 2 ) 0.255 0.313 0.395 0.496 0.583 0.692
As can be seen from the above table, the concentration of the washing liquid which can be maintained in the present invention is 2wt%, and the corresponding amine escape loss is only 0.313kg/t CO 2 While the highest concentration of amine in the washing liquid in the prior art is 6wt%, the average value of the corresponding amine escape loss is 0.496kg/t CO 2 The method provided by the invention can reduce the amine escape by 36.9 percent compared with the prior art.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims (10)

1. A system for capturing carbon dioxide by a wet method, which is characterized by comprising an absorption tower (10), wherein the absorption tower (10) comprises an absorption zone (101) and a washing zone (102) from bottom to top, the absorption zone (101) is used for contacting and reacting raw gas containing carbon dioxide with an absorbent to obtain a pre-purified gas and an absorbent rich liquid, and the washing zone (102) is used for washing the pre-purified gas to obtain purified gas;
a washing tank (12) communicated with the bottom of the washing zone (102) for storing the washing rich liquid obtained by the washing;
the top end of the regeneration tower (20) is communicated with the bottom end of the absorption zone (101) through a first pipeline (1) and is used for resolving the absorbent rich liquid to obtain regenerated gas and absorbent lean liquid, wherein the absorbent lean liquid is divided into a lean liquid a and a lean liquid b;
a regeneration gas separator (24) which is communicated with the top end of the regeneration tower (20) through a third pipeline (3) and is used for condensing the regeneration gas to obtain condensate and product gas, wherein the condensate is divided into cold liquid A and cold liquid B;
an underground tank (23) communicated with the bottom end of the regeneration gas separator (24) and used for storing the cold liquid A;
the bottom end of the regeneration gas separator (24) is also communicated with the top end of the washing zone (102) and is used for introducing the cold liquid B into the washing zone (102) to wash the pre-purified gas.
2. The system of claim 1, wherein a bottom end of the wash tank (12) communicates with a top end of the wash zone (102).
3. The system according to claim 1 or 2, wherein the bottom end of the washing tank (12) communicates with the first line (1).
4. A system according to any one of claims 1-3, wherein the upper end of the absorption zone (101) communicates with the bottom end of the regeneration column (20) via a second line (2) for introducing the lean liquid a into the absorption column (10) for the reaction in contact with the feed gas.
5. The system according to claim 4, wherein the system further comprises a heat exchanger (25) in communication with the first line (1), the second line (2), respectively, for exchanging heat of the absorbent rich liquid with the lean liquid a.
6. A system according to claim 4 or 5, wherein the second line (2) is provided with a lean liquor cooler (11) for cooling the lean liquor a.
7. A system according to any one of claims 1-6, wherein a regeneration gas cooler (21) is provided on the third line (3) for cooling the regeneration gas.
8. The system according to any one of claims 1-7, wherein the system further comprises a boiler (22) in communication with the bottom of the regeneration tower (20) for supplying heat to the regeneration tower (20).
9. The system according to any one of claims 1-8, wherein a bottom of the regeneration tower (20) is in communication with the underground tank (23) for leading the lean liquid b out of the regeneration tower (20).
10. A method of wet capturing carbon dioxide, characterized in that it is carried out in a system according to any one of claims 1-9.
CN202111271603.1A 2021-10-29 2021-10-29 System and method for wet capturing carbon dioxide Pending CN116059793A (en)

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CN202111271603.1A CN116059793A (en) 2021-10-29 2021-10-29 System and method for wet capturing carbon dioxide

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