CN115245728A - Device for capturing carbon in tail gas after combustion and application thereof - Google Patents

Abstract

The invention provides a device for capturing carbon in tail gas after combustion, which comprises a flue gas treatment device, a filter, a membrane absorber, an absorption tower, a lean-rich liquid heat exchanger, a membrane regenerator and a regeneration tower, wherein the flue gas treatment device is connected with the filter, the filter is respectively connected with the membrane absorber and the absorption tower through different pipelines, a liquid outlet of the membrane absorber and a liquid outlet of the absorption tower are communicated with an inlet of the lean-rich liquid heat exchanger, and an outlet of the lean-rich liquid heat exchanger is respectively connected with a liquid inlet of the membrane regenerator and a liquid inlet of the regeneration tower. The invention adopts a combined device of the membrane contactor and the conventional absorption tower, and the two aspects of synergistic action can greatly improve the treatment efficiency; meanwhile, the amine absorption liquid prepared by special preparation contains amino acid salt, an activating agent and a polymerization inhibitor, can show high reactivity and high desorption rate, and can realize 95% of carbon dioxide recovery rate.

Description

A device for capturing carbon from exhaust gas after combustion and its application

technical field

The invention relates to the field of flue gas CO ₂ capture, in particular to IPC classification number B01D53/14, and more particularly to a device for capturing carbon from exhaust gas after combustion and its application.

Background technique

As climate warming becomes more severe, carbon capture is a new technology for carbon neutrality, mainly by capturing carbon dioxide and storing it underground, on the seafloor or for other purposes. In theory, it is not difficult to "capture" carbon. Carbon dioxide reacts with amines, and the two combine at low temperature and separate at high temperature. Commonly employed techniques for chemical solvent absorption and desorption have been industrialized for decades and are well established for industrial carbon dioxide production. However, in order to achieve the goal of carbon neutrality, large-scale recycling of industrial combustion waste gas, the production cost per ton of carbon dioxide for conventional chemical absorption is not economical. In addition, the conventional absorption tower has a limited gas-liquid contact area and a small volumetric mass transfer coefficient, resulting in a low carbon dioxide capture efficiency, further increasing the energy consumption cost, and the absorption liquid used in the carbon capture process is due to its absorption And the speed of analysis is slower, so that the recovery rate of carbon dioxide is relatively low.

Chinese patent CN109304078A provides a carbon dioxide capture system and method, including at least a carbon dioxide absorption tower, a stripper, a compressor, and a first flasher, wherein the first flasher is connected to the liquid outlet of the stripper, and the compressor is connected to the first flasher. The gas outlet of the flasher is connected with the inlet of the stripper, and the system and method can effectively reduce the energy loss generated in the process. However, the gas-liquid contact area of the absorption tower used in the device is limited, which limits the treatment efficiency to a certain extent, and at the same time, ammonia water is used as the absorbent, and the removal rate of carbon dioxide can only reach about 83% at the highest.

SUMMARY OF THE INVENTION

In view of the above-mentioned technical problems, one aspect of the present invention provides a device for capturing carbon from exhaust gas after combustion, including a flue gas treatment device, a filter, a membrane absorber, an absorption tower, a lean-rich liquid heat exchanger, and a membrane regenerator , regeneration tower, the flue gas treatment device is connected with the filter, the filter is connected with the membrane absorber and the absorption tower respectively through different pipes, the liquid outlet of the membrane absorber and the liquid outlet of the absorption tower are connected with the rich and poor. The inlets of the liquid heat exchanger are connected, and the outlets of the lean-rich liquid heat exchanger are respectively connected with the liquid inlet of the membrane regenerator and the liquid inlet of the regeneration tower.

In some embodiments, the membrane absorber is arranged in parallel with the absorption column, and the membrane regenerator is arranged in parallel with the regeneration column.

In some embodiments, the flue gas treatment device is connected to a compressor fan.

In some embodiments, the flue gas treatment device includes a desulfurization device and/or a denitration device.

Preferably, the flue gas treatment device includes a desulfurization device and a denitration device.

In some embodiments, the type of absorption liquid used in the membrane absorber and the absorption tower includes amine absorption liquid, and the amine absorption liquid includes monoethanolamine, diethanolamine, triethanolamine, diisopropanolamine, methyldiethanolamine Ethanolamine, diisopropylamine, diglycolamine, ethylenediamine, piperazine, pyridine, sarcosinate, glycinate, alanine, leucine, phenylalanine, tryptophan, glutamate One or more of amino acid salt, lysine salt, methionine salt and cystine salt.

Preferably, the amine absorption solution comprises sarcosinate, glycinate, alanine, leucine, phenylalanine, tryptophan, glutamate, lysine, methyl sulfide One of amino acid salt and cystine salt aqueous solution.

More preferably, the amine absorption liquid further includes an active agent and a polymerization inhibitor.

In some embodiments, the outlets of the membrane regenerator and the regeneration tower are respectively connected to the inlet of the reboiler, the reboiler is connected to the bottom of the regeneration tower, and the reboiler is connected to the lean-rich liquid heat exchanger. connected, the lean-rich liquid heat exchanger is connected with the top of the absorption tower.

In some embodiments, the gas outlet of the membrane regenerator is connected to the condenser through a vacuum pump, and the gas outlet of the regeneration tower is connected to the condenser.

In some embodiments, the carbon dioxide and part of the steam released from the membrane regenerator and the regeneration tower pass through the condenser and then the steam is condensed and refluxed into the regeneration tower. At the same time, the capture of carbon dioxide can be completed, and the captured carbon dioxide is sent to the next step. , and further liquefaction treatment.

In some embodiments, the flue gas undergoes a mass transfer process with the absorption liquid in the absorption tower through the membrane absorber, and the gas after absorbing carbon dioxide is directly discharged into the atmosphere.

In some embodiments, the carbon dioxide released from the membrane regenerator and the regeneration tower to regenerate the lean liquid is connected to the top of the absorption tower through a lean-rich liquid heat exchanger.

In some embodiments, the membrane absorber and the membrane regenerator use a multi-layer composite membrane, and the structure of the composite membrane from bottom to top sequentially includes a substrate, a PVDF layer, a hydrophilic layer, a nano-selective _CO2 layer, The protective layer.

In some embodiments, the protective layer is a highly hydrophobic anti-blocking protective layer.

In some embodiments, the substrate of the membrane absorber is different from that of the membrane regenerator, the substrate of the membrane absorber is PET, and the substrate of the membrane regenerator is one of PVDF and PEEK.

Another aspect of the present invention provides the application of a device for capturing carbon from exhaust gas after combustion, which is used for capturing CO ₂ in flue gas of steel mills, power plants and cement plants.

Beneficial effects:

The invention adopts the combined device of a membrane contactor and a conventional absorption tower, and the two aspects synergize and can greatly improve the treatment efficiency; at the same time, the specially formulated amine absorption liquid contains amino acid salt, activator and polymerization inhibitor, which can show high reactivity and a faster desorption rate, 95% carbon dioxide recovery rate can be achieved; in addition, the membrane absorber and membrane regenerator in the present invention both use multi-layer composite membranes, including nano-scale selective permeable _CO2 membranes, and the composite surface is anti-pollution The protective layer can ensure the recovery effect and avoid the blocking of the membrane layer caused by the pollution of other impurities and affect the effect of carbon capture.

Description of drawings

Fig. 1 is the schematic diagram of the device for carbon capture in the present invention;

Figure 2 is a schematic diagram of the membrane structure of the membrane absorber and the membrane regenerator in the present invention.

Among them, 1. compressor; 2. flue gas treatment device; 3. filter; 4. membrane absorber; 5. absorption tower; 6. lean-rich liquid heat exchanger; 7. regeneration tower; 8. membrane regenerator; 9. Condenser; 10. Reboiler; 11. Vacuum pump.

101, substrate; 102, PVDF layer; 103, hydrophilic layer; 104, nano-selective _CO2 layer; 105, protective layer.

Detailed ways

Example 1

Please refer to Fig. 1 and Fig. 2, a device for capturing carbon from exhaust gas after combustion includes a flue gas treatment device 2, a filter 3, a membrane absorber 4, an absorption tower 5, a lean-rich liquid heat exchanger 6, and a membrane regenerator 8 , regeneration tower 7, the flue gas treatment device 2 is connected with the filter 3, the filter 3 is connected with the membrane absorber 4 and the absorption tower 5 through different pipelines, the liquid outlet of the membrane absorber 4, absorption The liquid outlet of the tower 5 is communicated with the inlet of the lean-rich liquid heat exchanger 6, and the outlet of the lean-rich liquid heat exchanger 6 is respectively connected with the liquid inlet of the membrane regenerator 8 and the liquid inlet of the regeneration tower 7.

The membrane absorber 4 is arranged in parallel with the absorption tower 5 , and the membrane regenerator 8 is arranged in parallel with the regeneration column 7 .

The flue gas treatment device 2 is connected to the compressor fan 1 , and the compressor 1 delivers the flue gas to the flue gas treatment device 2 .

The flue gas treatment device 2 includes a desulfurization device and a denitration device to remove sulfur-containing compounds and nitrogen-containing compounds in the flue gas and ensure that the subsequently discharged atmosphere does not contain harmful gases.

The type of absorption liquid used in the membrane absorber 4 and the absorption tower 5 is an amine absorption liquid, and the amine absorption liquid includes an amino acid salt, an activator, and a polymerization inhibitor, and this type of amine absorption liquid can produce a high reaction with carbon dioxide. properties and faster desorption rates.

The outlets of the membrane regenerator 8 and the regeneration tower 7 are respectively communicated with the inlet of the reboiler 10, the reboiler 10 is connected to the bottom of the regeneration tower 7, and the reboiler 10 is connected to the lean-rich liquid heat exchanger. 6 is connected, the lean-rich liquid heat exchanger 6 is connected to the top of the absorption tower 5, and the lean-rich liquid heat exchanger 6 realizes the heat exchange between the rich liquid that has absorbed carbon dioxide and the lean liquid that has been depleted of carbon dioxide, and To the recycling of the regenerated liquid, the role of energy saving.

The gas outlet of the membrane regenerator 8 is connected with the condenser 9 through the vacuum pump 11, the gas outlet of the regeneration tower 7 is connected with the condenser 9, and the carbon dioxide and part of the steam released in the regeneration tower 7 directly enter through the gas outlet. into the condenser 9; the carbon dioxide and part of the steam released from the membrane regenerator 8 are input into the condenser pipe 9 through the vacuum pump 11.

The carbon dioxide and part of the steam released from the membrane regenerator 8 and the regeneration tower 7 pass through the condenser 9, and then the steam is condensed and refluxed into the regeneration tower 7, and the collection and storage of carbon dioxide can be completed at the same time.

The flue gas is directly discharged into the atmosphere after the carbon dioxide is absorbed by the absorption liquid in the membrane absorber 4 and the absorption tower 5 .

The regeneration liquid from the membrane regenerator 8 and the regeneration tower 7 that releases carbon dioxide and steam is connected to the top of the absorption tower 5 through the lean-rich liquid heat exchanger 6, and the regeneration liquid can be used for the next cycle.

The membrane absorber 4 and the membrane regenerator 8 use a multi-layer composite membrane. The structure of the composite membrane from bottom to top includes a substrate 101, a PVDF layer 102, a hydrophilic layer 103, a nano-selective _CO2 layer 104, protective layer 105 .

The protective layer 105 is a highly hydrophobic and anti-blocking protective layer.

The membrane absorber 4 is different from the substrate in the membrane regenerator 8, the membrane material of the membrane absorber 4 is PVDF, and the membrane material of the membrane regenerator 8 is PEEK.

Working principle: First, the flue gas is transported by the compressor 1, and then the flue gas is desulfurized and denitrified by the flue gas treatment device 2, and then the solid impurities in the flue gas are removed by the filter 3. The filtered flue gas At the same time, through the membrane absorber 4 and the absorption tower 5, on the one hand, the upper part of the absorption tower 5 enters the tower, and forms a reverse contact with a specific amine absorbing liquid to absorb the carbon dioxide in the flue gas; on the other hand, the amine in the membrane absorber 4 absorbs The carbon dioxide in the liquid and gas phase is combined on the membrane surface and realizes gas-liquid mass transfer from carbon dioxide to the absorption liquid, forming a rich liquid together, and the gas from which the carbon dioxide has been removed is discharged into the atmosphere, and then enters the lean-rich liquid heat exchanger 6 for heating. Exchange, play the role of saving energy, then flow to the membrane regenerator 8 and regeneration tower 7 at the same time, release carbon dioxide and part of the steam, then carbon dioxide and part of the steam enter the condenser 9, the steam is condensed into a liquid state and returned to the regeneration tower 7, carbon dioxide It can be transported to the next step for recovery and storage; at the same time, the regenerated amine absorption liquid that releases carbon dioxide in the regeneration tower 7 and the membrane regenerator 8 returns to the absorption tower 5 through the lean-rich liquid heat exchanger 6 for the next cycle.

Claims (10)

1. A device for capturing carbon from tail gas after combustion, characterized in that it comprises a flue gas treatment device (2), a filter (3), a membrane absorber (4), an absorption tower (5), a lean-rich liquid heat exchanger (6), a membrane regenerator (8), a regeneration tower (7), the flue gas treatment device (2) is connected to a filter (3), and the filter (3) is respectively connected to the membrane absorber through different pipes (4), the absorption tower (5) is connected, the liquid outlet of the membrane absorber (4), the liquid outlet of the absorption tower (5) are connected with the inlet of the lean-rich liquid heat exchanger (6), and the rich-poor liquid heat exchanger (6) is connected. The outlet of the liquid heat exchanger (6) is respectively connected with the liquid inlet of the membrane regenerator (8) and the liquid inlet of the regeneration tower (7). 2 . The device for capturing carbon from exhaust gas after combustion according to claim 1 , wherein the membrane absorber ( 4 ) is arranged in parallel with the absorption tower ( 5 ), and the membrane regenerator ( 8 ) is connected to the regeneration The towers (7) are arranged in parallel. 3 . The device for capturing carbon from exhaust gas after combustion according to claim 1 , wherein the flue gas treatment device ( 2 ) is connected to a compressor fan ( 1 ). 4 . 4 . The device for capturing carbon from exhaust gas after combustion according to claim 3 , wherein the flue gas treatment device ( 2 ) comprises a desulfurization device and/or a denitration device. 5 . 5. The carbon capture device for post-combustion tail gas according to any one of claims 1-4, wherein the type of absorption liquid used in the membrane absorber (4) and the absorption tower (5) comprises amine Absorption liquid, the amine absorption liquid includes monoethanolamine, diethanolamine, triethanolamine, diisopropanolamine, methyldiethanolamine, diisopropylamine, diethylene glycolamine, ethylenediamine, piperazine, pyridine, sarcosine One of salt, glycinate, alanine, leucine, phenylalanine, tryptophan, glutamate, lysine, methionine and cystinate or more. 6 . The device for capturing carbon from exhaust gas after combustion according to claim 1 , wherein the outlets of the membrane regenerator ( 8 ) and the regeneration tower ( 7 ) are respectively connected to the inlet of the reboiler ( 10 ). 7 . The reboiler (10) is connected with the bottom of the regeneration tower (7), the reboiler (10) is connected with the lean-rich liquid heat exchanger (6), the lean-rich liquid heat exchanger (6) ) is connected to the top of the absorption tower (5). 7. A device for capturing carbon from exhaust gas after combustion according to claim 1, characterized in that the gas outlet of the membrane regenerator (8) is connected to the condenser (9) through a vacuum pump (11), and the regeneration The gas outlet of the column (7) is connected to the condenser (9). 8 . The device for capturing carbon from tail gas after combustion according to claim 7 , wherein the regeneration lean liquid of carbon dioxide released from the membrane regenerator (8) and the regeneration tower (7) is replaced by lean and rich liquid. 9 . The heater (6) is connected to the top of the absorption tower (5). 9 . The device for capturing carbon from exhaust gas after combustion according to claim 1 , wherein the membrane absorber ( 4 ) and the membrane regenerator ( 8 ) use a multi-layer composite membrane, and the structure of the composite membrane From bottom to top, it includes a substrate (101), a PVDF layer (102), a hydrophilic layer (103), a nano-selective _CO2 layer (104), and a protective layer (105). 10 . The application of the device for capturing carbon from exhaust gas after combustion according to any one of claims 1 to 9 , wherein it is used for capturing CO ₂ in flue gas of steel mills, power plants and cement plants. 11 .

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