CN115738597A - Low-energy-consumption carbon dioxide capture and regeneration method - Google Patents
Low-energy-consumption carbon dioxide capture and regeneration method Download PDFInfo
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- CN115738597A CN115738597A CN202211190458.9A CN202211190458A CN115738597A CN 115738597 A CN115738597 A CN 115738597A CN 202211190458 A CN202211190458 A CN 202211190458A CN 115738597 A CN115738597 A CN 115738597A
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Abstract
The invention relates to a low-energy-consumption carbon dioxide capture regeneration method, which is used for collecting and regenerating CO regenerated at the top of a regeneration tower 2 The low-level heat energy contained in the gas evaporates the working medium and absorbs the low-level heat energy, and the steam of dimethyl ether or similar working medium is compressed to the corresponding saturated pressure for condensation and releases heat for the regeneration of the absorbent at a higher temperature or other energy requirements; after condensation, the liquid working medium under high pressure is decompressed and flashed, the liquid is sent to a working medium evaporator to evaporate and absorb low-level heat energy, and the flashed working medium steam and the working medium steam generated by the working medium evaporator are sent to a compressor to be boosted to form closed cycle. The working medium evaporates and absorbs low-level heat energy at a lower temperature level, and the working medium vapor is condensed and releases heat at a higher temperature level after being compressed, so that the method is used in the fields of absorbent regeneration and the like during carbon dioxide capture so as to reduce the consumption of regenerated vapor.
Description
Technical Field
The invention belongs to the technical field of carbon dioxide recovery, and particularly relates to a low-energy-consumption carbon dioxide capturing and regenerating method.
Background
In the process industry for realizing product production or environmental and ecological protection, the process and the public engineering devices thereof have a large amount of material flows containing low-level heat energy of 40-100 ℃, and generally, the low-level heat energy of the material flows can only be utilized for a small part of limited fields such as demineralized water heating or winter heating and the like. But due to the large number, most of the waste water is cooled by air cooling or circulating water so as to meet the process requirement of stream cooling. Therefore, most of the low-level heat energy is not well utilized, and energy and primary water resources are additionally consumed, so that waste of energy and resources is caused.
In the pathway to achieve carbon neutralization goals, low CO 2 Partial pressure gases (e.g., flue gases) require the capture of CO by the CCUS prior to discharge to the atmosphere 2 And then either utilizing or sealing to achieve carbon sequestration. Chemical absorption is the most realistic CO capture over a very long period of time that can be expected 2 A method. However, chemical absorption traps CO 2 In time, the regeneration process of the absorbent consumes a large amount of low pressure steam or other similar quality energy to provide the energy required for regeneration at higher temperatures. The energy consumed by regeneration is carried away by gas at the temperature of 98 ℃ at the top of the regeneration tower. The overhead gas is mainly CO 2 And steam, cooling to below-40 deg.C, and separating out condensed water to obtain high-purity CO 2 To finally complete CO in the CCUS process 2 And (4) trapping.
Low partial pressure of CO 2 The regeneration process of the capture of the gas is the part of the path of the CCUS with the highest energy consumption and the highest operating cost, and the CO is currently recovered from the low partial pressure 2 Trapping 1 ton of CO in gas 2 About 2 to 3 tons of low-pressure steam are consumed. This huge external regenerative heat loss constitutes a large part of the energy consumption and operating costs, preventing the large-scale industrial application of the CCUS.
Disclosure of Invention
The invention aims to solve the problem of energy waste and provide a low-energy-consumption carbon dioxide capturing and regenerating method which greatly reduces the steam consumption in the process.
The invention aims to provide a low-energy-consumption carbon dioxide capture and regeneration method, which is used for absorbing CO flowing out from the bottom of an absorption tower 2 After the pressure of the rich solution is increased, the rich solution exchanges heat with the lean solution from the bottom of the regeneration tower T-102 in a lean/rich solution heat exchanger E-102; feeding the rich solution with the increased temperature into a rich solution inlet at the upper part of the regeneration tower T-102 to regenerate in the regeneration tower T-102;
the rich liquid flows from top to bottom in the regeneration tower T-102, and absorbed CO 2 Is desorbed and becomes a lean solution at the bottom of the regeneration tower T-102; the gas mixture flowing out of the top of the regeneration tower T-102 enters a working medium evaporator E-105; the working medium steam in the working medium evaporator E-105 is subjected to pressure boosting and then condensed in the reboiler E-106 to release heat, the released heat heats intermediate state lean and rich liquid flowing into the reboiler E-106 from the bottom of the regeneration tower T-102, and the intermediate state lean and rich liquid absorbs the heat and then is conveyed to the bottom of the regeneration tower T-102 for circulation; the liquid working medium out of the reboiler E-106 enters a working medium separator V-102 for flash evaporation, the flash evaporated gas is sent to a working medium compressor K-101, and the liquid is sent to a working medium evaporator E-105 for circulation.
Further, absorbed CO flowing out from the bottom of the absorption column 2 The pressure of the rich liquid is increased by a rich liquid pump P-101.
Further, the liquid-rich inlet is positioned below a tower tray section T-102 of the regeneration tower.
Further, the lean solution after heat exchange is pressurized by a lean solution pump, passes through a lean solution cooler E-103, is cooled by circulating cooling water, is sent to the upper part of an absorption tower, and reacts with low partial pressure CO in the absorption tower 2 The gas flows in the reverse direction and becomes absorbed CO 2 The rich liquid flows out from the bottom of the absorption tower.
Further, a lean solution pump P-102 is used for pressurizing after flowing out of the bottom of the regeneration tower T-102, and the lean solution is formed for circulation.
Further, in the working fluid evaporator E-105, the gas mixture is cooled and passed through CO 2 The separator V-101 separates pure CO 2 And is sent out to the next process of the CCUS.
Further, the CO is 2 The liquid separated by the separator V-101 is sent to a regeneration tower T-1 through a reflux pump P-10302, and a liquid inlet at the upper part of the regeneration tower, which is positioned above a tower tray section 2 of the regeneration tower T-102.
Furthermore, working medium steam is dimethyl ether working medium steam, and the dimethyl ether working medium steam is boosted through a working medium compressor (K-101); regenerated CO at the top of the regeneration tower 2 The low-level heat energy at 40-100 ℃ contained in the gas evaporates the working substance dimethyl ether, and the steam of the working substance dimethyl ether is compressed to 100-120 ℃ saturation pressure for condensation.
Further, a demister 1 is arranged at the top of the regeneration tower T-102.
Further, the CO is 2 The top of the separator V-101 is provided with a demister 1.
Compared with the prior art, the invention has the beneficial effects that: the invention adopts the characteristics of low-temperature evaporation and high-temperature condensation of the working medium, effectively utilizes the energy of the tower top regenerated gas or similar low-level heat energy, is used for the regeneration of the absorbent at a higher temperature level or other energy requirements, reduces the consumption of regenerated steam, and has important effects on energy conservation and carbon emission reduction.
Drawings
FIG. 1 is a schematic flow diagram of the low energy consumption carbon dioxide capture regeneration method of the present invention.
Detailed Description
The apparatus and process of the present invention will be described in further detail with reference to the accompanying drawings:
as shown in FIG. 1, in the low-energy-consumption method for capturing and regenerating carbon dioxide, absorbed CO flows out from the bottom of the absorption tower 2 After the pressure of the rich solution is increased by a rich solution pump P-101, the rich solution exchanges heat with lean solution from the bottom of a regeneration tower T-102 in a lean/rich solution heat exchanger E-102; after the heat exchange of the rich liquid, the temperature is increased (for example, from 55 ℃ to 104 ℃), the rich liquid with the increased temperature is sent to a rich liquid inlet at the upper part of the regeneration tower T-102 (the rich liquid inlet is positioned below the tower tray section 2), and regeneration is carried out in the regeneration tower T-102; the temperature of the lean solution is reduced (such as from 113 deg.C to 66 deg.C), the lean solution with reduced temperature is pressurized by lean solution pump, cooled by circulating cooling water via lean solution cooler E-103, sent to the upper part of absorption tower, and mixed with low partial pressure CO in the absorption tower 2 Gas counter-current flowBecome to absorb CO 2 The rich liquid flows out from the bottom of the absorption tower;
in the regeneration tower T-102, the rich liquid flows from top to bottom, the temperature is gradually increased, and the absorbed CO is 2 Desorbed and becomes barren solution at the bottom of the regeneration tower T-102, flows out from the bottom of the regeneration tower and then enters a barren solution pump P-102 for pressurization to form barren solution (namely absorbent) for circulation; the water vapor and CO flow out of the top of the regeneration tower T-102 2 And a small amount of absorbent mist, the gas mixture being cooled (e.g. to 40 ℃) in working medium evaporator E-105, passing CO 2 The separator V-101 separates pure CO 2 The next step of feeding the material into CCUS; CO 2 2 The liquid separated in separator V-101 (liquid comprising a large amount of water and a small amount of absorbent less than 5%) is fed by reflux pump P-103 into the liquid inlet at the upper part of regeneration column T-102 (liquid inlet located above tray section 2) to wash the regeneration gas.
The heat for the regeneration of the rich solution is provided by a reboiler E-106, working medium steam (such as dimethyl ether working medium steam) in a working medium evaporator E-105 is boosted by a working medium compressor K-101 and condensed in the reboiler E-106 to release heat, the released heat heats the intermediate lean and rich solution flowing into the reboiler E-106 from the bottom of the regeneration tower T-102, and the intermediate lean and rich solution absorbs the heat and then is conveyed to the bottom of the regeneration tower T-102 for circulation; the liquid working medium out of the reboiler E-106 enters a working medium separator V-102 for flash evaporation, the flash evaporated gas is sent to a working medium compressor K-101, and the liquid is sent to a working medium evaporator E-105 for circulation.
In this example, the top of the regeneration column T-102 and CO 2 The top of the separator V-101 is provided with a demister 1 which can filter the mist 1, CO in the regeneration tower T-102 2 Demister 1 in separator V-101 further filters CO 2 The mist in (1). In addition, after the gas mixture in working medium evaporator E-105 is cooled (e.g. to 40 ℃), the gas mixture may be passed through desorption gas water cooler E-104 to further remove water vapor from the gas mixture.
The regenerated CO at the top of the regeneration tower 2 The low-level heat energy of 40-100 ℃ contained in the gas evaporates the dimethyl ether or the similar working medium, absorbs the low-level heat energy, and the steam of the dimethyl ether or the similar working medium is compressed toCondensing at 100-120 deg.c corresponding to saturated pressure to release heat for the regeneration of absorbent at relatively high temperature or other energy requirement; after condensation, the liquid working medium under high pressure is decompressed and flashed, the liquid is sent to a working medium evaporator to evaporate and absorb low-level heat energy, and the flashed working medium steam and the working medium steam generated by the working medium evaporator are sent to a compressor to be boosted to form closed cycle. The dimethyl ether or similar working media have different boiling points under different pressures, evaporate and absorb low-level heat energy at a relatively low temperature position, condense and release heat energy at a high temperature position after the working media steam is compressed, and are used in the fields of absorbent regeneration and the like during carbon dioxide capture so as to reduce the consumption of regenerated steam, namely the low-level heat energy at 40-100 ℃ can be recycled and used for the energy demand at 100-120 ℃.
The technological indexes of the invention are as follows:
(1) Raw materials and products
--CO 2 Collecting scale: 100 million tons/year
-flue gas composition: 9.5% of CO 2 ；71％N 2 ；0.2％Ar；2.5％O 2 ；16.7％H 2 O；
- -product CO 2 Purity: 99.5% of CO 2
(2) Index of solvent regeneration consumption
-low pressure steam: 160 ton/hr
Compressor shaft power: 26MW
(3) Saves 23 percent of energy compared with the traditional regeneration process
Therefore, if the invention can be adopted, the external energy supply in the regeneration process can be greatly reduced, and the invention has important significance for promoting the large-scale commercial application of the CCUS and realizing the target assistance of carbon neutralization.
The invention effectively recycles the low-level heat energy of 40-100 ℃, and can also be used for the gas at the top of the stripping tower, the fraction at the top of the rectifying tower and the low-level heat energy of 40-100 ℃ which is difficult to recycle by various reaction units, so as to be used in the application field of the energy utilization of 100-120 ℃, thereby reducing the total energy consumption and the carbon dioxide emission of the whole system. The technology not only reduces the power consumption when air cooling and water cooling are needed when the low-level heat energy cannot be effectively utilized, but also reduces the high-grade energy consumption in the regeneration process or rectification process of chemical absorption, and the like, and has important effects on energy conservation and carbon emission reduction.
Claims (10)
1. A low-energy-consumption carbon dioxide capturing and regenerating method is characterized by comprising the following steps: absorbed CO flowing out from the bottom of the absorption column 2 After the pressure of the rich liquid is increased, the rich liquid exchanges heat with the lean liquid from the bottom of the regeneration tower (T-102) in a lean/rich liquid heat exchanger (E-102); the rich liquid with the increased temperature is sent to a rich liquid inlet at the upper part of the regeneration tower (T-102) to be regenerated in the regeneration tower (T-102);
the rich liquid flows from top to bottom in the regeneration tower (T-102), and the absorbed CO flows from top to bottom 2 Is desorbed and becomes a lean solution at the bottom of the regeneration tower (T-102); the gas mixture flowing out of the top of the regeneration tower (T-102) enters a working medium evaporator (E-105); working medium steam in the working medium evaporator (E-105) is subjected to pressure boosting and then condensed in the reboiler (E-106) to release heat, the released heat heats intermediate lean-rich liquid flowing into the reboiler (E-106) from the bottom of the regeneration tower (T-102), and the intermediate lean-rich liquid absorbs the heat and then is conveyed to the bottom of the regeneration tower (T-102) for circulation; the liquid working medium out of the reboiler (E-106) enters a working medium separator (V-102) for flash evaporation, the flash evaporated gas is sent to a working medium compressor (K-101), and the liquid is sent to a working medium evaporator (E-105) for circulation.
2. The low energy consumption carbon dioxide capture regeneration process of claim 1, characterized by: the method is characterized in that: absorbed CO flowing out of the bottom of the absorption column 2 The pressure of the rich liquid is increased by a rich liquid pump (P-101).
3. The low energy consumption carbon dioxide capture regeneration process of claim 1, characterized by: the method is characterized in that: the liquid-rich inlet is positioned below a tower tray section (2) of the regeneration tower (T-102).
4. According to claim 1The low-energy-consumption carbon dioxide capturing and regenerating method is characterized by comprising the following steps: the method is characterized in that: after heat exchange, the barren solution is pressurized by a barren solution pump, is cooled by circulating cooling water through a barren solution cooler (E-103), is sent to the upper part of an absorption tower, and reacts with low partial pressure CO in the absorption tower 2 The gas flows in the reverse direction and becomes absorbed CO 2 The rich liquid flows out from the bottom of the absorption tower.
5. The low energy consumption carbon dioxide capture regeneration process of claim 1, characterized by: the method is characterized in that: and (4) flowing out of the bottom of the regeneration tower (T-102) and then pressurizing by a barren liquor pump (P-102) to form barren liquor for circulation.
6. The low energy consumption carbon dioxide capture regeneration process of claim 1, characterized by: the method is characterized in that: in the working fluid evaporator (E-105), the gas mixture is cooled and passed through CO 2 The pure CO is separated by a separator (V-101) 2 And is sent out to the next process of the CCUS.
7. The low energy consumption carbon dioxide capture regeneration process of claim 6, characterized by: the method is characterized in that: the CO is 2 The liquid separated by the separator (V-101) is sent to a liquid inlet at the upper part of the regeneration tower (T-102) through a reflux pump (P-103) to wash regeneration gas, and the liquid inlet is positioned above a tray section (2) of the regeneration tower (T-102).
8. The low energy consumption carbon dioxide capture regeneration process of claim 1, characterized by: the method is characterized in that: the working medium steam adopts dimethyl ether working medium steam, and the dimethyl ether working medium steam is boosted through a working medium compressor (K-101); regenerated CO at the top of the regeneration tower 2 The low-level heat energy at 40-100 ℃ contained in the gas evaporates the working substance dimethyl ether, and the steam of the working substance dimethyl ether is compressed to 100-120 ℃ saturation pressure for condensation.
9. The low energy consumption carbon dioxide capture regeneration process of claim 1, characterized by: the method is characterized in that: the top of the regeneration tower (T-102) is provided with a demister (1).
10. The low energy consumption carbon dioxide capture regeneration process of claim 6, characterized by: the method is characterized in that: the CO is 2 The top of the separator (V-101) is provided with a demister (1).
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