CN219518342U - Carbon trapping system for low-concentration carbon dioxide flue gas - Google Patents
Carbon trapping system for low-concentration carbon dioxide flue gas Download PDFInfo
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- CN219518342U CN219518342U CN202320948542.6U CN202320948542U CN219518342U CN 219518342 U CN219518342 U CN 219518342U CN 202320948542 U CN202320948542 U CN 202320948542U CN 219518342 U CN219518342 U CN 219518342U
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- 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
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Abstract
The utility model discloses a carbon trapping system for low-concentration carbon dioxide flue gas, which comprises an absorption tower, a desorption tower, a first heat pump unit, a second heat pump unit, a lean-rich liquid heat exchanger, a reflux tank and a reboiler, wherein the absorption tower is connected with the desorption tower through a pipeline; the first heat pump unit is respectively connected with a lean solution outlet of the lean-rich solution heat exchanger, a lean solution inlet of the absorption tower, a tower bottom liquid outlet of the desorption tower and a tower bottom liquid inlet of the desorption tower; the first heat pump unit is suitable for transferring the heat of the absorbed lean liquid to the tower bottom liquid of the desorption tower; the second heat pump unit is respectively connected with a desorption gas outlet of the desorption tower, an inlet of the reflux tank, an intermediate liquid inlet of the desorption tower and a first liquid inlet of the reboiler; the second heat pump unit is suitable for transferring the absorbed heat of the desorption gas to the intermediate liquid of the desorption tower; according to the system, the first heat pump system and the second heat pump system are arranged, so that the residual heat utilization rate of lean solution and desorption gas is improved, the steam consumption is reduced, and the energy consumption and the cost in the carbon capturing process are effectively reduced.
Description
Technical Field
The utility model relates to the technical field of carbon capture, in particular to a carbon capture system for low-concentration carbon dioxide flue gas.
Background
With the increase of the greenhouse effect of carbon dioxide, carbon Capture and Utilization and Sequestration (CCUS) technology is increasingly being appreciated by various countries. In order to achieve the temperature control target of 1.5 ℃, the global carbon dioxide emission reduction must reach more than 80% by 2050, and Carbon Capture Utilization and Sequestration (CCUS) is a necessary technical means for achieving the target.
Among carbon trapping technologies of low-concentration carbon dioxide flue gas, carbon trapping technologies using an organic alcohol amine solution as an absorbent become a main technology for large-scale industrial application. The technology uses alkaline alcohol amine solution as solvent, and the CO in the flue gas is subjected to two processes of absorption and desorption 2 And (3) collecting and purifying, wherein the rich liquid and the lean liquid in the system realize the recycling of part of waste heat through a heat exchanger.
Disclosure of Invention
In order to enrich the types of carbon trapping systems and increase the selection space of energy-saving modes in the carbon trapping process, the utility model provides a carbon trapping system for low-concentration carbon dioxide flue gas.
The embodiment of the utility model provides a carbon trapping system for low-concentration carbon dioxide flue gas, which comprises an absorption tower, a desorption tower, a first heat pump unit, a second heat pump unit, a lean-rich liquid heat exchanger, a reflux tank and a reboiler, wherein the absorption tower is connected with the desorption tower through a pipeline;
the first heat pump unit is respectively connected with a lean solution outlet of the lean-rich solution heat exchanger, a lean solution inlet of the absorption tower, a tower bottom liquid outlet of the desorption tower and a tower bottom liquid inlet of the desorption tower; the first heat pump unit is suitable for transferring the heat of the absorbed lean solution to the tower bottom solution of the desorption tower;
the second heat pump unit is respectively connected with a desorption gas outlet of the desorption tower, an inlet of the reflux tank, an intermediate liquid inlet of the desorption tower and a first liquid inlet of the reboiler; the second heat pump unit is adapted to transfer the heat of the absorbed stripping gas to the intermediate liquid of the stripping column.
In one or some alternative embodiments, the first heat pump unit includes a first evaporator, a first absorber, a first solution pump, a first concentrator, and a first condenser connected in sequence;
the first condenser is respectively connected with the first evaporator, the first absorber and a tower bottom liquid inlet of the desorption tower;
the first evaporator is respectively connected with a lean solution outlet of the lean-rich solution heat exchanger and a lean solution inlet of the absorption tower;
the first absorber is connected with a tower bottom liquid outlet of the desorption tower;
the first evaporator is adapted to absorb heat of lean liquid from the lean-rich liquid heat exchanger;
the first absorber is adapted to absorb the refrigerant vapor from the first evaporator and emit absorption heat;
the first solution pump is adapted to pump dilute solution from the first absorber into the first concentrator;
the first concentrator is adapted to heat concentrate the dilute solution from the first absorber to a concentrated solution;
the first condenser is adapted to transfer heat of the absorbed refrigerant vapor from the first condenser to a bottoms liquid of the desorber.
In one or some alternative embodiments, the second heat pump unit includes a second evaporator, a second absorber, a second solution pump, a second concentrator, and a second condenser connected in sequence;
the second condenser is respectively connected with the second evaporator, the second absorber and a first liquid inlet of a reboiler;
the second evaporator is respectively connected with a desorption gas outlet of the desorption tower and an inlet of the reflux tank;
the second absorber is connected with an intermediate liquid inlet of the desorption tower;
the second evaporator is adapted to absorb heat of desorption gas from the desorption column;
the second absorber is adapted to absorb the refrigerant vapor from the second evaporator and emit absorption heat;
said second solution pump being adapted to pump dilute solution from said second absorber into said second concentrator;
the second concentrator is adapted to heat concentrate the dilute solution from the second absorber to a concentrated solution;
the second condenser is adapted to transfer the heat of the absorbed refrigerant vapor from the second condenser to the intermediate liquid of the desorber.
In one or some alternative embodiments, a lean liquid outlet of the desorber is connected to a lean liquid inlet of the lean-rich liquid heat exchanger;
the rich liquid outlet of the absorption tower is connected with the rich liquid inlet of the lean rich liquid heat exchanger; the rich liquid outlet of the lean rich liquid heat exchanger is connected with the rich liquid inlet of the desorption tower;
in one or some alternative embodiments, a vapor outlet of the reboiler is connected to a vapor inlet of the desorber, and a liquid outlet of the reboiler is connected to a liquid inlet of the desorber.
In one or some alternative embodiments, the carbon capture system for low concentration carbon dioxide flue gas further comprises a reflux pump and a compression liquefaction unit;
the reflux drum is adapted to separate CO-containing gas 2 Gas and condensed water;
the reflux pump is respectively connected with a condensate water outlet of the reflux tank and a lean solution inlet of the absorption tower;
the gas outlet of the reflux tank is connected with the inlet of the compression liquefaction unit; the compression liquefaction unit is suitable for compressing CO 2 。
In one or some alternative embodiments, the carbon capture system for low concentration carbon dioxide flue gas further comprises a stripping gas cooler;
and the inlet of the desorption gas cooler is connected with the second evaporator, and the outlet of the desorption gas cooler is connected with the inlet of the reflux tank.
In one or some alternative embodiments, the carbon capture system for low concentration carbon dioxide flue gas further comprises a lean liquor cooler;
and an inlet of the lean solution cooler is connected with the first evaporator, and an outlet of the lean solution cooler is connected with a lean solution inlet of the absorption tower.
In one or some alternative embodiments, the intermediate liquid outlet of the desorber is connected to the second liquid inlet of the reboiler.
In one or some alternative embodiments, the carbon capture system for low concentration carbon dioxide flue gas further comprises a rich liquor transfer pump;
the rich liquid delivery pump is arranged between a rich liquid outlet of the absorption tower and a rich liquid inlet of the lean rich liquid heat exchanger.
In one or some alternative embodiments, the carbon capture system for low concentration carbon dioxide flue gas further comprises a lean liquid transfer pump;
the lean solution delivery pump is arranged between a lean solution outlet of the desorption tower and a lean solution inlet of the lean-rich solution heat exchanger.
In one or some alternative embodiments, the carbon capture system for low concentration carbon dioxide flue gas further comprises a tower bottoms circulation pump;
the tower bottom liquid circulating pump is arranged between the tower bottom liquid outlet of the desorption tower and the first absorber.
In one or some alternative embodiments, the carbon capture system for low concentration carbon dioxide flue gas further comprises an intermediate liquid circulation pump;
the intermediate liquid circulating pump is arranged between the intermediate liquid outlet of the desorption tower and the second absorber.
The technical scheme provided by the embodiment of the utility model has the beneficial effects that at least:
according to the carbon trapping system for the low-concentration carbon dioxide flue gas, provided by the embodiment, the heat of the lean solution is recovered through the first heat pump unit, and the recovered heat is used for heating the tower bottom liquid of the desorption tower, so that the residual heat utilization rate of the lean solution is improved, and the steam consumption of a reboiler is reduced; the heat of the desorption gas is recovered through the second heat pump unit, and the recovered heat is used for heating the intermediate liquid of the desorption tower, so that the utilization rate of the residual heat of the desorption gas is improved, and the steam consumption of a reboiler is reduced; by arranging the first heat pump system and the second heat pump system, the energy consumption and the cost in the carbon capturing process are effectively reduced.
Additional features and advantages of the utility model will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the utility model. The objectives and other advantages of the utility model may be realized and attained by the structure particularly pointed out in the written description and drawings.
The technical scheme of the utility model is further described in detail through the drawings and the embodiments.
Drawings
The accompanying drawings are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate the utility model and together with the embodiments of the utility model, serve to explain the utility model. In the drawings:
fig. 1 is a schematic structural diagram of a carbon capturing system for low-concentration carbon dioxide flue gas according to an embodiment of the present utility model.
In the figure:
1 is an absorption tower;
2 is a desorption tower;
3 is a first heat pump unit, 301 is a first evaporator, 302 is a first absorber, 303 is a first solution pump, 304 is a first concentrator, 305 is a first condenser, 306 is a first condensate pump;
4 is a second heat pump unit, 401 is a second evaporator, 402 is a second absorber, 403 is a second solution pump, 404 is a second concentrator, 405 is a second condenser, 406 is a second condensate pump;
the device comprises a lean-rich liquid heat exchanger 5, a reflux tank 6, a reboiler 7, a compression liquefaction unit 8, a lean liquid cooler 9 and a desorption gas cooler 10;
11 is a reflux pump, 12 is a rich liquid delivery pump, 13 is a lean liquid delivery pump, 14 is a tower kettle liquid circulating pump, and 15 is an intermediate liquid circulating pump;
the third evaporator 16, the washing liquid buffer tank 17, the washing pump 18, the washing liquid cooler 19 and the flue gas pretreatment device 20.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In the description of the present utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "far," "near," "front," "rear," and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, merely to facilitate description of the present utility model and simplify the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.
The inventors have found that a carbon capture system with an organic alcohol amine solution as an absorbent can be used for low partial pressure CO in flue gas 2 The method is characterized in that the method is used for collecting the residual heat in the gas at the top of the desorption tower, and the residual heat in the gas at the top of the desorption tower is recycled, so that the energy consumption of the carbon collecting process is reduced. In the existing waste heat recovery technology, the compression heat pump is mostly adopted to recover the waste heat in the gas at the top of the desorption tower, the technology utilizes the phase change work generated by electric energy or mechanical energy, the operation parts are more and are easy to damage, the maintenance is complex, and the compression heat pump is greatly influenced by the refrigerant, has high power consumption and is not beneficial to popularization and application.
Based on this, the embodiment of the present utility model provides a carbon capturing system for low-concentration carbon dioxide flue gas, and the following description will refer to specific embodiments.
Examples
The present embodiment provides a carbon capturing system for low concentration carbon dioxide flue gas, referring to fig. 1, including an absorption tower 1, a desorption tower 2, a first heat pump unit 3, a second heat pump unit 4, a lean-rich liquid heat exchanger 5, a reflux drum 6, and a reboiler 7;
the first heat pump unit 3 is respectively connected with a lean liquid outlet of the lean and rich liquid heat exchanger 5, a lean liquid inlet of the absorption tower 1, a tower bottom liquid outlet of the desorption tower 2 and a tower bottom liquid inlet of the desorption tower 2; the first heat pump unit 3 is adapted to transfer the heat of the absorbed lean liquid to the tower bottoms of the desorption tower 2;
the second heat pump unit 4 is respectively connected with a desorption gas outlet of the desorption tower 2, an inlet of the reflux drum 6, an intermediate liquid inlet of the desorption tower 2 and a first liquid inlet of the reboiler 7; the second heat pump unit 4 is adapted to transfer the absorbed heat of desorption gas to the intermediate liquid of the desorption column 2;
the lean liquid outlet of the desorption tower 2 is connected with the lean liquid inlet of the lean-rich liquid heat exchanger 5; the rich liquor outlet of the absorption tower 1 is connected with the rich liquor inlet of the lean rich liquor heat exchanger 5; the rich liquid outlet of the lean-rich liquid heat exchanger 5 is connected with the rich liquid inlet of the desorption tower 2; the steam outlet of the reboiler 7 is connected with the steam inlet of the desorption tower 2, and the liquid outlet of the reboiler 7 is connected with the liquid inlet of the desorption tower 2.
In this embodiment, a lean solution outlet of the desorption tower 2 is arranged at the bottom of the desorption tower 2, lean solution flowing out from the bottom of the desorption tower 2 enters the first heat pump unit 3 after being subjected to heat exchange by the lean-rich solution heat exchanger 5, and after the first heat pump unit 3 absorbs heat of the lean solution, the lean solution flows to a lean solution inlet of the absorption tower 1; the tower bottom liquid in the desorption tower 2 flows into the first heat pump unit 3 from the tower bottom liquid outlet of the desorption tower 2, and the first heat pump unit 3 transfers the absorbed heat to the tower bottom liquid; the liquid in the tower kettle after temperature rising flows to the desorption tower 2, and returns to the desorption tower 2 through the liquid in the tower kettle inlet of the desorption tower 2. The tower bottom liquid outlet of the desorption tower 2 and the tower bottom liquid inlet of the desorption tower 2 are arranged at the bottom of the desorption tower 2, and the tower bottom liquid outlet of the desorption tower 2 is positioned above the tower bottom liquid inlet of the desorption tower 2.
In this embodiment, the second heat pump unit 4 may be disposed above the desorption tower 2, the gas outlet of the desorption tower 2 is disposed at the top of the desorption tower 2, the desorption gas discharged from the top of the desorption tower 2 flows into the second heat pump unit 4, and after the second heat pump unit 4 absorbs the heat of the desorption gas, the desorption gas flows into the reflux drum 6; the intermediate liquid in the desorption tower 2 flows into the second heat pump unit 4 from the intermediate liquid outlet of the desorption tower 2, and the second heat pump unit 4 transfers the absorbed heat to the intermediate liquid; the intermediate liquid after temperature rise flows to the reboiler 7, enters the reboiler 7 through a first liquid inlet of the reboiler 7, is flashed in the reboiler 7, and contains CO after flash evaporation 2 The vapor of (2) enters the desorption tower 2 through the vapor inlet of the desorption tower 2, and the residual liquid enters the desorption tower 2 through the liquid inlet of the desorption tower 2. The middle liquid outlet of the desorption tower 2 is arranged in the middle of the desorption tower 2, the liquid inlet of the desorption tower 2 is arranged at the bottom of the desorption tower 2, the vapor inlet of the desorption tower 2 is arranged at the middle liquid outlet of the desorption tower 2 and the liquid inlet of the desorption tower 2Between the ports.
In the present embodiment, the lean solution is capable of reacting with CO 2 The absorbent in which the decarburization reaction occurs may be, for example, an ethanolamine solution; rich liquid refers to CO in flue gas 2 Decarburization reaction occurs, and CO is absorbed 2 Is a sorbent of (a).
In a specific embodiment, referring to fig. 1, the first heat pump unit 3 may be an absorption heat pump, and includes a first evaporator 301, a first absorber 302, a first solution pump 303, a first condenser 304, and a first condenser 305 connected in sequence; the first condenser 305 is connected to the first evaporator 301 and the first absorber 302, respectively. The first evaporator 301 is connected to the lean liquid outlet of the lean-rich liquid heat exchanger 5 and the lean liquid inlet of the absorption tower 1, respectively; the first condenser 305 is connected with a tower bottom liquid inlet of the desorption tower 2; the first absorber 302 is connected to the bottom liquid outlet of the desorption column 2. The specific process of transferring the heat of the absorbed lean liquid to the bottoms of the desorption column 2 by the first heat pump unit 3 may include:
the lean liquid from the lean-rich liquid heat exchanger 5 passes through the first evaporator 301, and after the heat of the lean liquid is absorbed by the refrigerant water in the first evaporator 301, the refrigerant water is evaporated into refrigerant steam and enters the first absorber 302; the concentrated lithium bromide solution in the first absorber 302 absorbs the refrigerant steam to become dilute lithium bromide solution, and emits absorption heat, and meanwhile, the tower bottom liquid of the desorption tower 2 enters the first absorber 302, and the emitted absorption heat heats the tower bottom liquid to raise the temperature; the lithium bromide dilute solution is sent to a first concentrator 304 by a first solution pump 303, heated and concentrated in the first concentrator 304 to be lithium bromide concentrated solution, and then returned to the first absorber 302; the refrigerant vapor generated by heating and concentrating in the first concentrator 304 enters the first condenser 305, and meanwhile, the tower bottom liquid from the first absorber 302 enters the first condenser 305, and the refrigerant vapor continuously heats the tower bottom liquid to the temperature of about 115 ℃; the condensate of the refrigerant vapor generated in the first condenser 305 enters the first evaporator 301, and is used as the refrigerant water of the first evaporator 301 for the next cycle.
In a specific embodiment, referring to fig. 1, the second heat pump unit 4 may be an absorption heat pump, and includes a second evaporator 401, a second absorber 402, a second solution pump 403, a second concentrator 404, and a second condenser 405 that are sequentially connected; the second condenser 405 is connected to the second evaporator 401 and the second absorber 402, respectively. The second evaporator 401 is respectively connected with a desorption gas outlet of the desorption tower 2 and an inlet of the reflux drum 6; the second condenser 405 is connected to the first liquid inlet of the reboiler 7; the second absorber 402 is connected to the intermediate liquid inlet of the desorption column 2. The specific process of transferring the absorbed heat of desorption gas to the intermediate liquid of the desorption column 2 by the second heat pump unit 4 may include:
the desorption gas from the top of the lean desorption tower 2 passes through a second evaporator 401, and after the heat of desorption gas is absorbed by the refrigerant water in the second evaporator 401, the refrigerant water is evaporated into refrigerant steam and enters a second absorber 402; the concentrated lithium bromide solution in the second absorber 402 absorbs the refrigerant vapor to become dilute lithium bromide solution, and emits absorption heat, and meanwhile, the intermediate liquid of the desorption tower 2 enters the second absorber 402, and the emitted absorption heat heats the intermediate liquid to raise the temperature; the lithium bromide dilute solution is sent to a second concentrator 404 by a second solution pump 403, heated and concentrated to be lithium bromide concentrated solution in the second concentrator 404, and then returned to the second absorber 402; the refrigerant vapor generated by heating and concentrating in the second concentrator 404 enters the second condenser 405, and meanwhile, the tower bottom liquid from the second absorber 402 enters the second condenser 405, and the refrigerant vapor continuously heats the intermediate liquid to further raise the temperature to about 105 ℃; the condensate of the refrigerant vapor generated in the second condenser 405 enters the second evaporator 401 to be used as the refrigerant water of the second evaporator 401 for the next cycle.
In the embodiment of the present utility model, the first heat pump unit further includes a first condensate pump 306 disposed between the first condenser 305 and the first evaporator 301, and the first condensate pump 306 is configured to pump the refrigerant vapor condensate generated in the first condenser 305 into the first evaporator 301; the second heat pump unit further comprises a second condensate pump 406 arranged between the second condenser 405 and the second evaporator 401, the second condensate pump 406 being arranged to pump the refrigerant vapour condensate generated in the first condenser 305 into the second evaporator 401.
In this embodiment, the carbon capturing system for low-concentration carbon dioxide flue gas further includes a steam supply device (not shown in the figure) and a steam condensate recovery device (not shown in the figure), where the steam supply device is connected to the reboiler 7, the first concentrator 304 and the second concentrator 404, and can provide driving steam for the reboiler 7, the first concentrator 304 and the second concentrator 404, that is, provide heat for the reboiler 7, the first concentrator 304 and the second concentrator 404; the steam condensate recovery device is connected with the reboiler 7, the first concentrator 304 and the second concentrator 404, and after driving steam to be converted into steam condensate, the steam condensate is fed into the steam condensate recovery device for recovery treatment.
According to the carbon trapping system for the low-concentration carbon dioxide flue gas, provided by the embodiment, the heat of the lean solution is recovered through the first heat pump unit 3, and the recovered heat is used for heating the tower bottom liquid of the desorption tower 2, so that the residual heat utilization rate of the lean solution is improved, and the steam consumption of the reboiler 7 is reduced; the heat of the desorption gas is recovered through the second heat pump unit 4, and the recovered heat is used for heating the intermediate liquid of the desorption tower 2, so that the utilization rate of the residual heat of the desorption gas is improved, and the steam consumption of the reboiler 7 is reduced.
In a specific embodiment, referring to fig. 1, the carbon capture system for low concentration carbon dioxide flue gas further comprises a lean liquor cooler 9 and a stripping gas cooler 10. An inlet of the lean solution cooler 9 is connected with the first evaporator 301, an outlet of the lean solution cooler 9 is connected with a lean solution inlet of the absorption tower 1, lean solution from the first evaporator 301 flows to the absorption tower 1 after being cooled by the lean solution cooler 9, and is sprayed downwards from the lean solution inlet at the upper part of the absorption tower 1 to absorb CO in the flue gas 2 . An inlet of the desorption gas cooler 10 is connected with the second evaporator 401, an outlet of the desorption gas cooler 10 is connected with an inlet of the reflux tank 6, the desorption gas discharged from the top of the desorption tower 2 flows to the reflux tank 6 after being cooled by the desorption gas cooler 10, and is separated into condensed water and CO-containing water in the reflux tank 6 2 And (3) gas. In this embodiment, the cold flow medium for the lean solution cooler 9 and the desorption gas cooler 10 may be cooling water.
In a specific embodiment, referring to fig. 1, the carbon capture system for low concentration carbon dioxide flue gas further comprises a reflux pump 11 and a compression liquefaction unit 8. Reflux pump 11 is connected to the condensate outlet of reflux drum 6 and the lean liquid inlet of absorption tower 1, respectivelyThe vapor condensate in the reflux drum 6 can be pumped into the absorption tower 1 through the reflux pump 11 through the port, and sprayed downward from the lean liquid inlet of the absorption tower 1. The gas outlet of the reflux tank 6 is connected with the inlet of the compression liquefaction unit 8, and CO contained in the reflux tank 6 2 The gas enters the compression and liquefaction unit 8 to be compressed and liquefied.
In a specific embodiment, referring to fig. 1, the carbon capturing system for low concentration carbon dioxide flue gas further includes a rich liquid transfer pump 12 disposed between the rich liquid outlet of the absorption tower 1 and the rich liquid inlet of the lean rich liquid heat exchanger 5; the rich liquid outlet of the absorption tower 1 is arranged at the bottom of the absorption tower 1, and the rich liquid flowing out of the bottom of the absorption tower 1 can be pumped into the lean-rich liquid heat exchanger 5 by the rich liquid delivery pump 12.
In a specific embodiment, referring to fig. 1, the carbon capturing system for low concentration carbon dioxide flue gas further includes a lean solution transfer pump 13 disposed between the lean solution outlet of the desorption tower 2 and the lean solution inlet of the lean-rich solution heat exchanger 5; the lean liquid outlet of the desorption tower 2 is arranged at the bottom of the desorption tower 2, and the lean liquid flowing out of the bottom of the desorption tower 2 can be pumped into the lean-rich liquid heat exchanger 5 by the lean liquid delivery pump 13.
In a specific embodiment, referring to fig. 1, the carbon capturing system for low concentration carbon dioxide flue gas further includes a tower bottom liquid circulating pump 14 disposed between the tower bottom liquid outlet of the desorption tower 2 and the first absorber 302; the bottoms of the desorption column 2 can be pumped into the first absorber 302 by the bottoms circulation pump 14.
In a specific embodiment, referring to fig. 1, the carbon capture system for low concentration carbon dioxide flue gas further includes an intermediate liquid circulation pump 15 disposed between the intermediate liquid outlet of the desorption tower 2 and the second absorber 402; the intermediate liquid of the desorption column 2 can be pumped into the second absorber 402 by the intermediate liquid circulation pump 15.
In one embodiment, referring to FIG. 1, the carbon capture system for low concentration carbon dioxide flue gas may further comprise a third evaporator 16 disposed between the compression liquefaction unit 8 and the reflux drum 6, the CO-containing gas from the reflux drum 6 2 The gas enters the third evaporator 16 and is cooled down further in the third evaporator 16After warming, the CO is obtained 2 Enters a compression liquefaction unit 8 for treatment.
In a specific embodiment, referring to fig. 1, the carbon capturing system for low-concentration carbon dioxide flue gas further includes a flue gas pretreatment device 20 connected to the absorption tower 1, and the flue gas is subjected to decarburization treatment in the absorption tower 1 after being subjected to impurity removal and temperature reduction in the flue gas pretreatment device 20.
In a specific embodiment, referring to fig. 1, the energy-saving carbon capture system for low-concentration carbon dioxide flue gas further includes a wash buffer tank 17, a wash pump 18 and a wash cooler 19 connected in sequence, and the absorption tower 1 is connected to the wash buffer tank 17 and the wash cooler 19, respectively. The washing liquid in the washing liquid buffer tank 17 is used for absorbing the gas volatilized by the absorbent, the washing liquid absorbed with the volatilized gas is pumped into the washing liquid cooler 19 by the washing pump 18 for cooling, and the cooled washing liquid is returned to the absorption tower 1.
In this embodiment, the first heat pump unit 3 and the second heat pump unit 4 are temporarily not turned on immediately after the carbon capturing system for low-concentration carbon dioxide flue gas is started. For a period of time the system is operated, the temperature, pressure and CO at various locations within the system 2 The output of the first heat pump unit 3 and the second heat pump unit 4 can be started at the moment, so that the first heat pump unit 3 and the second heat pump unit 4 can smoothly perform waste heat recovery. When the first heat pump unit 3 and the second heat pump unit 4 are not activated, the heat required for desorption by the desorption column 2 is supplied from the reboiler 7, and the heat of the reboiler 7 is supplied from the driving steam supplied from the steam supply means.
The carbon capture system for low-concentration carbon dioxide flue gas provided by the embodiment is used for capturing carbon dioxide, and comprises a driving working condition and an operating working condition, wherein the driving working condition refers to a working condition when the first heat pump unit 3 and the second heat pump unit 4 are not started; operating conditions the first heat pump unit 3 and the second heat pump unit 4 are operating after start-up.
In this embodiment, the intermediate liquid outlet of the desorption tower 2 is connected to the second liquid inlet of the reboiler 7, and the intermediate liquid of the desorption tower 2 may enter the reboiler 7 to be flashed. The carbon capture system for low-concentration carbon dioxide flue gas provided by the embodiment is used for capturing carbon dioxide, and the technological process under the driving working condition can specifically comprise the following steps:
after removing impurities and reducing the temperature of the flue gas (about 40 ℃), the flue gas enters the absorption tower 1 from a flue gas inlet at the bottom of the absorption tower 1, lean solution is sprayed downwards from a lean solution inlet at the top of the absorption tower 1, and CO in the flue gas 2 Countercurrent contact with lean solution, decarburization reaction occurs, and decarburization gas flows through an absorption section and a tail gas washing section of the absorption tower 1 in sequence and is discharged from the top of the tower; lean liquid for absorbing CO in flue gas 2 Then, the mixture is changed into a rich liquid, and the temperature of the rich liquid is 48-56 ℃.
The rich liquid is discharged from the bottom of the absorption tower 1, flows to the desorption tower 2 after being heated to 90-100 ℃ by the lean-rich liquid heat exchanger 5, is sprayed downwards from a rich liquid inlet at the top of the desorption tower 2, and is in the process of flowing from top to bottom under the action of gravity, and CO in the rich liquid 2 The reaction product is heated and decomposed in the tower to obtain desorption gas, and the desorption gas contains CO 2 And water vapor; because the internal temperature of the desorption tower 2 is higher, the desorption gas is discharged from the top of the desorption tower 2; the discharged desorption gas is cooled by a desorption gas cooler 10 and then enters a reflux tank 6, and is separated into CO-containing gas in the reflux tank 6 2 Gas and condensed water; the condensed water in the reflux drum 6 is returned to the absorption tower 1 and contains CO 2 The gas is sent to a compression liquefaction unit 8 for treatment. The reboiler 7 is arranged at the side or lower part of the bottom of the desorption tower 2, and intermediate liquid of the desorption tower 2 enters the reboiler 7 to be flashed and then returns to the bottom of the desorption tower 2, so that heat is provided for the desorption process, and the heat of the reboiler 7 is derived from driving steam provided by the steam supply device.
After the rich liquid is completely desorbed in the desorption tower 2, the rich liquid is converted into lean liquid, the lean liquid is discharged from the bottom of the desorption tower 2 and is sent to the lean-rich liquid heat exchanger 5 by the lean liquid delivery pump 13, the rich liquid is fully heat-exchanged with the rich liquid from the bottom of the absorption tower 1, the rich liquid is cooled further by the lean liquid cooler 9 after the temperature is reduced to a first preset temperature value, and the lean liquid flows to the absorption tower 1 after being cooled to a second preset temperature value, is sprayed downwards from a lean liquid inlet of the absorption tower 1 and is mixed with CO in the flue gas 2 Decarburization reaction occurs.
The carbon capture system for low-concentration carbon dioxide flue gas provided by the embodiment is used for capturing carbon dioxide, and the process flow under the operation condition can specifically comprise:
starting the first heat pump unit 3 and the second heat pump unit 4;
removing impurities from the flue gas, cooling (about 40 ℃), entering the bottom of the absorption tower 1, spraying the lean solution discharged by the lean solution cooler 9 downwards from a lean solution inlet of the absorption tower 1, enabling the flue gas to contact with the lean solution in a countercurrent manner, performing decarburization reaction, and discharging decarburization gas from the top of the tower after sequentially flowing through an absorption section and a tail gas washing section of the absorption tower 1; lean liquid for absorbing CO in flue gas 2 Then, the mixture is changed into a rich liquid, and the temperature of the rich liquid is 48-56 ℃.
The rich liquid at the bottom of the absorption tower 1 is heated to 90-100 ℃ by a lean-rich liquid heat exchanger 5 and then enters a desorption tower 2, flows from top to bottom in the desorption tower 2 and is desorbed;
the intermediate liquid of the desorption tower 2 is pumped into the second heat pump unit 4 by an intermediate liquid circulating pump 15, the temperature is raised to about 105 ℃ after heat exchange circulation in the second heat pump unit 4, the intermediate liquid after the temperature is raised returns to the reboiler 7 for flash evaporation, and CO is generated in the reboiler 7 2 The vapor and the residual liquid of (2) are returned to the desorption tower; pumping the tower bottom liquid of the desorption tower 2 into a first heat pump unit 3 by a tower bottom liquid circulating pump 14, heating to about 115 ℃ after heat exchange circulation of the first heat pump unit 3, and returning the heated tower bottom liquid to the bottom of the desorption tower 2 for flash evaporation; the two flash gas rising processes are continuously contacted with the rich liquid flowing down from the upper part of the desorption tower 2 to carry out CO 2 And (5) desorption.
The rich liquid is converted into lean liquid after desorption, the lean liquid flows out from the bottom of the desorption tower 2, is cooled to 59-65 ℃ after primary heat exchange by the lean-rich liquid heat exchanger 5, is cooled to 54-60 ℃ after heat exchange circulation by the first heat pump unit 3, and is cooled to the absorption temperature (about 40 ℃) by the lean liquid cooler 9 after twice heat exchange, and then enters the absorption tower 1.
The desorption gas is discharged from the top of the desorption tower 2, enters the second heat pump unit 4 to exchange heat and circulate, then is cooled to 65-75 ℃, and the desorbed gas after heat exchange is cooled by the desorption gas cooler 10 and enters the reflux tank 6 to be separated into CO in the reflux tank 6 2 Gas and condensed water, containing CO 2 The gas is sent to a subsequent compression liquefaction unit 8, and the condensed water is sent back to the upper part of the absorption tower 1.
According to the carbon trapping system for the low-concentration carbon dioxide flue gas, provided by the embodiment, the heat of the lean solution is absorbed through the first heat pump unit 3, the temperature of the lean solution after being heated is reduced, and the consumption of cooling water of the lean solution cooler 9 is reduced; the second heat pump unit 4 absorbs the heat of the desorption gas, and the temperature of the desorption gas after the heat is taken is reduced, thereby reducing the consumption of the cooling water in the desorption gas cooler 10.
The carbon trapping system for low-concentration carbon dioxide flue gas provided by the embodiment is used for trapping CO in the flue gas through the absorption tower 1 2 Absorbing and desorbing CO by a desorption tower 2 2 The lean liquid and the rich liquid are subjected to heat exchange through the lean-rich liquid heat exchanger 5, the absorbed heat of the lean liquid is transferred to the tower bottom liquid of the desorption tower 2 through the first heat pump unit 3, and the absorbed heat of desorption gas is transferred to the intermediate liquid of the desorption tower 2 through the second heat pump unit 4, so that the process is simple and reasonable, and the popularization and the application are easy.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present utility model without departing from the spirit or scope of the utility model. The present disclosure is not limited to the precise construction that has been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims. Thus, it is intended that the present utility model also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (13)
1. The carbon trapping system for the low-concentration carbon dioxide flue gas is characterized by comprising an absorption tower, a desorption tower, a first heat pump unit, a second heat pump unit, a lean-rich liquid heat exchanger, a reflux tank and a reboiler;
the first heat pump unit is respectively connected with a lean solution outlet of the lean-rich solution heat exchanger, a lean solution inlet of the absorption tower, a tower bottom liquid outlet of the desorption tower and a tower bottom liquid inlet of the desorption tower; the first heat pump unit is suitable for transferring the heat of the absorbed lean solution to the tower bottom solution of the desorption tower;
the second heat pump unit is respectively connected with a desorption gas outlet of the desorption tower, an inlet of the reflux tank, an intermediate liquid inlet of the desorption tower and a first liquid inlet of the reboiler; the second heat pump unit is adapted to transfer the heat of the absorbed stripping gas to the intermediate liquid of the stripping column.
2. The carbon capture system for low concentration carbon dioxide flue gas of claim 1, wherein the first heat pump unit comprises a first evaporator, a first absorber, a first solution pump, a first concentrator, and a first condenser connected in sequence;
the first condenser is respectively connected with the first evaporator, the first absorber and a tower bottom liquid inlet of the desorption tower;
the first evaporator is respectively connected with a lean solution outlet of the lean-rich solution heat exchanger and a lean solution inlet of the absorption tower;
the first absorber is connected with a tower bottom liquid outlet of the desorption tower;
the first evaporator is adapted to absorb heat of lean liquid from the lean-rich liquid heat exchanger;
the first absorber is adapted to absorb the refrigerant vapor from the first evaporator and emit absorption heat;
the first solution pump is adapted to pump dilute solution from the first absorber into the first concentrator;
the first concentrator is adapted to heat concentrate the dilute solution from the first absorber to a concentrated solution;
the first condenser is adapted to transfer heat of the absorbed refrigerant vapor from the first condenser to a bottoms liquid of the desorber.
3. The carbon capture system for low concentration carbon dioxide flue gas of claim 1, wherein the second heat pump unit comprises a second evaporator, a second absorber, a second solution pump, a second concentrator, and a second condenser connected in sequence;
the second condenser is respectively connected with the second evaporator, the second absorber and a first liquid inlet of a reboiler;
the second evaporator is respectively connected with a desorption gas outlet of the desorption tower and an inlet of the reflux tank;
the second absorber is connected with an intermediate liquid inlet of the desorption tower;
the second evaporator is adapted to absorb heat of desorption gas from the desorption column;
the second absorber is adapted to absorb the refrigerant vapor from the second evaporator and emit absorption heat;
said second solution pump being adapted to pump dilute solution from said second absorber into said second concentrator;
the second concentrator is adapted to heat concentrate the dilute solution from the second absorber to a concentrated solution;
the second condenser is adapted to transfer the heat of the absorbed refrigerant vapor from the second condenser to the intermediate liquid of the desorber.
4. The carbon capture system for low concentration carbon dioxide flue gas of claim 1, wherein a lean liquid outlet of the desorber is connected to a lean liquid inlet of the lean rich liquid heat exchanger;
the rich liquid outlet of the absorption tower is connected with the rich liquid inlet of the lean rich liquid heat exchanger; and a rich liquid outlet of the lean rich liquid heat exchanger is connected with a rich liquid inlet of the desorption tower.
5. The carbon capture system for low concentration carbon dioxide flue gas of claim 1, wherein a vapor outlet of the reboiler is connected to a vapor inlet of the desorber and a liquid outlet of the reboiler is connected to a liquid inlet of the desorber.
6. The carbon capture system for low concentration carbon dioxide flue gas of claim 1, further comprising a reflux pump and a compression liquefaction unit;
the reflux drum is adapted to separate CO-containing gas 2 Gas and condensed water;
the reflux pump is respectively connected with a condensate water outlet of the reflux tank and a lean solution inlet of the absorption tower;
the gas outlet of the reflux tank is connected with the inlet of the compression liquefaction unit; the compression liquefaction unit is suitable for compressing CO 2 。
7. The carbon capture system for low concentration carbon dioxide flue gas of claim 3, further comprising a stripping gas cooler;
and the inlet of the desorption gas cooler is connected with the second evaporator, and the outlet of the desorption gas cooler is connected with the inlet of the reflux tank.
8. The carbon capture system for low concentration carbon dioxide flue gas of claim 2, further comprising a lean liquor cooler;
and an inlet of the lean solution cooler is connected with the first evaporator, and an outlet of the lean solution cooler is connected with a lean solution inlet of the absorption tower.
9. The carbon capture system for low concentration carbon dioxide flue gas of claim 1, wherein an intermediate liquid outlet of the desorber is connected to a second liquid inlet of the reboiler.
10. The carbon capture system for low concentration carbon dioxide flue gas of claim 1, further comprising a rich liquor transfer pump;
the rich liquid delivery pump is arranged between a rich liquid outlet of the absorption tower and a rich liquid inlet of the lean rich liquid heat exchanger.
11. The carbon capture system for low concentration carbon dioxide flue gas of claim 1, further comprising a lean solution transfer pump;
the lean solution delivery pump is arranged between a lean solution outlet of the desorption tower and a lean solution inlet of the lean-rich solution heat exchanger.
12. The carbon capture system for low concentration carbon dioxide flue gas of claim 2, further comprising a tower bottoms circulation pump;
the tower bottom liquid circulating pump is arranged between the tower bottom liquid outlet of the desorption tower and the first absorber.
13. The carbon capture system for low concentration carbon dioxide flue gas of claim 3, further comprising an intermediate liquid circulation pump;
the intermediate liquid circulating pump is arranged between the intermediate liquid outlet of the desorption tower and the second absorber.
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