CN115463516A - System and method for using flue gas waste heat for carbon capture regeneration - Google Patents
System and method for using flue gas waste heat for carbon capture regeneration Download PDFInfo
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- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 128
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 126
- 239000003546 flue gas Substances 0.000 title claims abstract description 121
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 117
- 230000008929 regeneration Effects 0.000 title claims abstract description 91
- 238000011069 regeneration method Methods 0.000 title claims abstract description 91
- 238000000034 method Methods 0.000 title claims abstract description 36
- 239000002918 waste heat Substances 0.000 title claims abstract description 27
- 239000007788 liquid Substances 0.000 claims abstract description 87
- 238000010521 absorption reaction Methods 0.000 claims abstract description 70
- 230000002745 absorbent Effects 0.000 claims abstract description 18
- 239000002250 absorbent Substances 0.000 claims abstract description 18
- 150000001412 amines Chemical class 0.000 claims description 31
- 238000011084 recovery Methods 0.000 claims description 31
- 238000010438 heat treatment Methods 0.000 claims description 14
- -1 alcohol amine Chemical class 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 4
- 238000000746 purification Methods 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 20
- 239000000463 material Substances 0.000 abstract description 15
- 238000004064 recycling Methods 0.000 abstract description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 22
- 229910002092 carbon dioxide Inorganic materials 0.000 description 11
- 239000001569 carbon dioxide Substances 0.000 description 11
- 239000007789 gas Substances 0.000 description 6
- 239000007791 liquid phase Substances 0.000 description 5
- 239000002699 waste material Substances 0.000 description 5
- 238000006477 desulfuration reaction Methods 0.000 description 4
- 230000023556 desulfurization Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000010248 power generation Methods 0.000 description 4
- 230000001172 regenerating effect Effects 0.000 description 4
- 239000003245 coal Substances 0.000 description 3
- 238000003795 desorption Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000009919 sequestration Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005262 decarbonization Methods 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 239000007857 degradation product Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
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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
- B01D53/1425—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
- B01D53/18—Absorbing units; Liquid distributors therefor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
-
- 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
Abstract
The invention relates to the technical field of carbon capture, and discloses a system and a method for using flue gas waste heat for carbon capture regeneration, wherein in the system, rich liquor generated in a carbon capture absorption tower sequentially enters a lean rich liquor heat exchanger, a rich liquor reheater and a regeneration tower, and the rich liquor in the regeneration tower is heated by a reboiler; exchanging heat between the barren solution generated in the regeneration tower and the rich solution in the barren and rich solution heat exchanger, and recycling the barren solution and the rich solution in the carbon capture absorption tower; a stream of flue gas from a boiler is subjected to heat exchange in an air preheater to obtain a first flue gas stream; exchanging heat between the other stream of flue gas from the boiler and rich liquid in a reboiler to obtain a second flue gas material stream; and the first flue gas material flow and the second flue gas material flow are converged and then exchange heat with the rich liquid in the rich liquid reheater, and then enter the carbon capture absorption tower for carbon capture. According to the invention, the flue gas waste heat generated by the boiler is fully used for the regeneration of the absorbent in the carbon capture unit, so that the energy utilization rate of the coal-fired unit is improved, and the regeneration energy consumption in the carbon capture unit is reduced.
Description
Technical Field
The invention relates to the technical field of carbon capture, in particular to a system and a method for using flue gas waste heat for carbon capture regeneration.
Background
At present, the electricity supply of China is still mainly based on thermal power, the installed capacity proportion of a thermal power generating set and the coal consumption of a coal-fired power plant are difficult to realize large-scale adjustment in a short period, and coal still occupies a dominant position in the energy structure of China. Therefore, under the dual effects of high carbon energy structure and rapid increase of energy demand, the CCS technology does not affect the economic developmentAnd on the premise of the safety of the exhibition and energy strategy, the low-carbon development is realized. The carbon capture and sequestration are the only existing carbon capture and sequestration which can greatly reduce the emission of electric power and industrial CO 2 Techniques to vent (up to 90%). If the carbon capture and sequestration technology is not adopted, the overall cost for realizing the long-term goal of slowing down climate change in China will rise by 25%.
In recent years, the carbon capture technology is developed rapidly, and a large number of new technologies and new methods emerge. The carbon trapping process by the alcohol amine method is mature and widely used in the industry at present, and the decarbonization method has the biggest problem of high energy consumption for trapping and regenerating the absorbent, wherein about 70 percent of energy consumption is concentrated in the regeneration part of the absorbent. At present, a heat source for desorbing carbon dioxide is mainly used for extracting partial steam from a low-pressure cylinder in a steam turbine of a coal-fired power plant unit, the power generation efficiency of the power plant is reduced by the method, the auxiliary load loss of the power plant is increased, and the power generation cost is high.
Disclosure of Invention
The invention aims to solve the problem that the carbon capture system in the prior art mainly supplies heat through steam generated by a steam turbine in a coal-fired power plant device, so that the power generation cost is high, and provides a system and a method for using flue gas waste heat for carbon capture regeneration.
The inventor finds that in a coal-fired power plant unit, the waste heat loss of flue gas generated by an industrial boiler accounts for 10% or more of the total energy, and the heat loss of the flue gas seriously influences the efficiency of the boiler and the unit efficiency. The flue gas after heat exchange of the air preheater in the unit belongs to low-grade waste heat resources, and is difficult to be effectively utilized in the unit of the coal-fired power plant due to high utilization difficulty and high utilization cost.
The inventor further researches and discovers that the waste heat energy of the flue gas generated by the industrial boiler is utilized in the carbon capture unit, so the inventor intends to couple the carbon capture unit with the coal-fired power plant unit, and the coupled system can fully utilize the waste heat energy of the flue gas generated in the boiler in the carbon capture unit, thereby reducing the energy consumption of the carbon capture unit and further reducing the power generation cost of the coal-fired power plant.
In order to achieve the above object, the present invention provides a system for carbon capture regeneration by using flue gas waste heat, the system comprising a carbon capture absorption tower, a lean-rich liquid heat exchanger, a rich liquid reheater, a regeneration tower, a reboiler and an air preheater, wherein,
rich liquid generated in the carbon capture absorption tower sequentially enters the lean-rich liquid heat exchanger, the rich liquid reheater and the regeneration tower, and rich liquid in the regeneration tower circularly enters the reboiler for heating and then returns to the regeneration tower;
the barren solution generated in the regeneration tower exchanges heat with the rich solution in the barren and rich solution heat exchanger, and then enters the carbon capture absorption tower for reuse;
exchanging heat between a stream of flue gas from a boiler and air in said air preheater to obtain a first stream of flue gas;
exchanging heat of another flue gas from the boiler with the rich liquid in the reboiler to obtain a second flue gas stream;
and after being converged, the first flue gas material flow and the second flue gas material flow exchange heat with the rich liquid in the rich liquid reheater, and then enter the carbon capture absorption tower for carbon capture.
Preferably, the system further comprises an amine recovery heater for heating and purifying the rich portion of the lean liquid produced in the regeneration column.
Preferably, another stream of flue gas from the boiler exchanges heat with the lean liquor in the amine recovery heater before entering the reboiler.
Preferably, the system further comprises a lean liquid cooler, and the lean liquid after exchanging heat with the rich liquid in the lean-rich liquid heat exchanger enters the lean liquid cooler for cooling before entering the carbon capture absorption tower.
A second aspect of the present invention provides a method for using flue gas waste heat for carbon capture regeneration, the method being implemented in a system including a carbon capture absorption tower, a lean-rich liquid heat exchanger, a rich liquid reheater, a regeneration tower, a reboiler, and an air preheater, the method including:
performing carbon capture in the carbon capture absorption tower, wherein the generated rich solution sequentially enters the lean-rich solution heat exchanger, the rich solution reheater and the regeneration tower, and the rich solution in the regeneration tower circularly enters the reboiler for heating and then returns to the regeneration tower;
the rich solution is regenerated in the regeneration tower, and the generated lean solution exchanges heat with the rich solution in the lean and rich solution heat exchanger and then enters the carbon capture absorption tower for reuse;
exchanging heat between a stream of flue gas from a boiler and air in said air preheater to obtain a first stream of flue gas;
exchanging heat of another flue gas from the boiler with the rich liquid in the reboiler to obtain a second flue gas stream;
and after being converged, the first flue gas material flow and the second flue gas material flow exchange heat with the rich solution in the rich solution reheater, and then enter the carbon capture absorption tower for carbon capture.
Preferably, the system further includes an amine recovery heater, and the method further includes injecting a part of the lean solution generated by the regeneration in the regeneration tower into the amine recovery heater for heating and purification, and then into the carbon capture absorption tower for reuse.
Preferably, 2 to 6 parts by volume of the lean liquid is injected into the amine recovery heater per 100 parts by volume of the lean liquid generated in the regeneration tower.
Preferably, another stream of flue gas from the boiler exchanges heat with the lean liquor in the amine recovery heater before entering the reboiler.
Preferably, the system further comprises a lean liquid cooler, the method further comprising: at least part of the lean solution after exchanging heat with the rich solution in the lean-rich solution heat exchanger enters the lean solution cooler for cooling before entering the carbon capture absorption tower.
Preferably, the absorbent in the carbon capture absorption tower is an alcohol amine absorption liquid.
In the invention, the coal-fired power plant unit is coupled with the carbon capture unit, so that the waste heat of the flue gas generated by the boiler is fully used for the regeneration of the absorbent in the carbon capture unit, the heat loss of the coal-fired unit is reduced, the energy utilization rate of the coal-fired unit is improved, the regeneration energy consumption in the carbon capture unit is reduced, and the operation cost is reduced.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of a system for using flue gas waste heat for carbon capture regeneration provided by the invention.
Description of the reference numerals
1-a boiler; 2-a carbon capture absorption tower; 3-carbon trapping draught fan; 4-a barren liquor pump; 5-lean liquor cooler; 6-a pregnant solution pump; 7-lean-rich liquor heat exchanger; an 8-amine recovery heater; 9-rich liquor reheater; 10-a regeneration column; 11-a reboiler; 12-air preheater.
Detailed Description
The following describes in detail embodiments of the present invention with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For numerical ranges, each range between its endpoints and individual point values, and each individual point value can be combined with each other to give one or more new numerical ranges, and such numerical ranges should be construed as specifically disclosed herein.
The existing carbon capture process comprises the following steps: after the flue gas in the boiler of the coal-fired power plant is desulfurized and denitrated, the flue gas exchanges heat with air in an air preheater to obtain waste flue gas; waste flue gas is subjected to desulfurization and denitrification treatment and then injected into a carbon capture unit for carbon capture, and a heat source for regenerating an absorbent in the carbon capture unit generally comes from a part of steam extracted by a low-pressure cylinder (or a medium-pressure cylinder or an auxiliary steam header) in a steam turbine of a coal-fired power plant unit or steam exhausted by a steam-driven draught fan.
In view of the above, the present invention provides a system for utilizing flue gas waste heat for carbon capture regeneration, referring to fig. 1 (in the figure, the dashed line indicates the flue gas flow direction, and the solid line indicates the liquid phase flow direction), in one embodiment, the system includes a carbon capture absorption tower 2, a lean-rich liquid heat exchanger 7, a rich liquid reheater 9, a regeneration tower 10, a reboiler 11, and an air preheater 12.
Rich solution generated in the carbon capture absorption tower 2 sequentially enters a lean rich solution heat exchanger 7, a rich solution reheater 9 and a regeneration tower 10, and rich solution in the regeneration tower 10 circularly enters a reboiler 11 for heating and then returns to the regeneration tower 10; the lean solution generated in the regeneration tower 10 exchanges heat with the rich solution in the lean-rich solution heat exchanger 7, and then enters the carbon capture absorption tower 2 for reuse.
In the present invention, the rich liquid in the carbon capture absorption tower 2 is sent to the lean-rich liquid heat exchanger 7 by the rich liquid pump 6. Here, the rich solution is absorbing CO 2 The lean solution is used for absorbing CO in the carbon capturing tower 2 The absorbent of (1).
In specific implementation, a rich liquid outlet of the carbon capture absorption tower 2 is communicated with a rich liquid inlet of the lean-rich liquid heat exchanger 7, a rich liquid outlet of the lean-rich liquid heat exchanger 7 is connected with a liquid phase inlet of the rich liquid reheater 9, and a liquid phase outlet of the rich liquid reheater 9 is connected with a liquid phase inlet of the regeneration tower 10, so that the rich liquid in the carbon capture absorption tower 2 can enter the regeneration tower 10 to regenerate the absorbent.
In a specific embodiment, the rich liquid outlet of the regeneration tower 10 is communicated with the reboiler 11, so that the rich liquid in the regeneration tower 10 is circulated into the reboiler 11 to be heated and then returned to the regeneration tower 10, and thus, the rich liquid in the regeneration tower 10 can be heated by the reboiler 11, and the rich liquid in the regeneration tower 10 can be subjected to desorption reaction to release CO 2 Thereby realizing the regeneration of the absorbent and obtaining the barren solution. The barren liquor outlet of the regeneration tower 10 is connected with the barren liquor inlet of the barren liquor-rich liquor heat exchanger 7 and the barren liquor inlet of the carbon capture absorption tower 2 in sequence, so that the absorbent barren liquor regenerated in the regeneration tower 10 can return to the carbon capture absorption tower 2 for the next carbon capture cycle.
A stream of flue gas from the boiler 1 is heat exchanged with air in an air preheater 12 to obtain a first stream of flue gas; another stream of flue gas from the boiler 1 is heat exchanged against rich liquid in a reboiler 11 to obtain a second stream of flue gas; the first flue gas material flow and the second flue gas material flow are converged and then exchange heat with the rich liquid in the rich liquid reheater 9, and then enter the carbon capture absorption tower 2 for carbon capture.
The exhaust flue gas after being used by the rich liquor reheater 9 is subjected to desulfurization and denitrification treatment, and then is injected into the carbon capture absorption tower 2 to be subjected to decarburization treatment. In addition, the flue gas and the rich liquid in the reboiler 11 are subjected to indirect heat exchange, i.e. there is no direct contact between the two.
During the concrete implementation, boiler 1 has first outlet flue and second outlet flue, and first outlet flue is connected with air heater 12's flue gas entry, and second outlet flue communicates with reboiler 11's flue gas entry, and reboiler 11's exhanst gas outlet joins the back with air heater 12's exhanst gas outlet and is connected to rich liquid reheater 9's exhanst gas entry, and rich liquid reheater 9's exhanst gas outlet and carbon capture absorption tower 2's exhanst gas entry linkage. Wherein, the flue gas of the rich liquor reheater 9 is conveyed to the carbon capture absorption tower 2 through the carbon capture induced draft fan 3.
Specifically, the method divides the flue gas (about 300 ℃) discharged from a draught fan of a boiler 1 into two streams, and obtains a first flue gas stream (120-130 ℃) after one stream of flue gas exchanges heat with air through an air preheater 12; the other flue gas can be used for heating and regenerating the rich solution in a reboiler 11 (the inlet temperature of the reboiler 11 is about 105-110 ℃, and the outlet temperature is about 110 ℃) at first stage to obtain a second flue gas material flow; and then the first flue gas stream and the second flue gas stream are mixed and secondarily used in a rich liquor reheater 9 to exchange heat with rich liquor (90-95 ℃) processed by a lean-rich liquor heat exchanger 7, so that the aim of preheating by a reboiler 11 is fulfilled. Therefore, the flue gas generated by the boiler 1 can be fully utilized in the carbon capture unit by the design of the system; meanwhile, in the system, the rich liquor reheater 9 in the carbon capture unit is arranged at the downstream of the air preheater 12, the heat exchange condition of the air preheater 12 is not influenced, and the temperature of hot air at the outlet of the preheater is kept unchanged. That is, the system provided by the invention can be CO without influencing the operation of the coal-fired power plant unit 2 Providing long-term, stable regenerationThe flue gas heat source greatly improves the energy utilization rate, thereby effectively reducing the energy consumption of the carbon capture system.
During regeneration of the absorbent in the regeneration tower 10, a portion of the absorbent may be contaminated or degraded, losing the ability to capture carbon dioxide, and if the absorbent continues to circulate through the system, not only will the system be burdened, but the degradation products will also increase the corrosion of the equipment. In a preferred embodiment, the system further comprises an amine recovery heater 8 for heating and purifying part of the barren solution generated in the regeneration tower 10, and the arrangement of the amine recovery heater 8 can remove impurities from the absorbent barren solution in the regeneration tower 10, and then the purified absorbent is put into the system for continuous recycling.
Further, a flow control valve (not shown in the drawings) is provided between the lean liquid outlet of the regeneration tower 10 and the liquid phase inlet of the amine recovery heater 8, so that the amount of the lean liquid entering the amine recovery heater 8 can be controlled by controlling the flow control valve. In the present invention, the flow control valve may be opened after a number of carbon capture cycles; the amount of the lean liquid that enters the amine recovery heater 8 in each carbon capture cycle may also be controlled by controlling the flow rate of the flow control valve.
In order to make full use of the residual heat of the flue gas, in the invention, another flue gas from the boiler 1 exchanges heat with the lean solution in the amine recovery heater 8 before entering the reboiler 11. In this way, the other flue gas is first used in the amine recovery heater 8, the temperature of the flue gas after heat exchange by the amine recovery heater 8 is about 160 ℃, then the other flue gas is used in the reboiler 11 for heating and regenerating the rich solution, and finally the other flue gas is merged with the flue gas after heat exchange by the air preheater 12 and then is used in the rich solution reheater 9 in a third stage.
In a preferred embodiment, the system further includes a lean liquid cooler 5, and at least part of the lean liquid after heat exchange with the rich liquid in the lean-rich liquid heat exchanger 7 is cooled in the lean liquid cooler 5 before entering the carbon capture absorption tower 2. The barren liquor treated by the rich liquor heat exchanger can be further cooled by the arrangement of the barren liquor cooler 5 and then passes through the barren liquorThe liquid pump 4 is conveyed to the carbon capture absorption tower 2 to continuously absorb CO 2 。
The method for using the flue gas waste heat for carbon capture regeneration is implemented in a system comprising a carbon capture absorption tower 2, a lean-rich liquid heat exchanger 7, a rich liquid reheater 9, a regeneration tower 10, a reboiler 11 and an air preheater 12, and comprises the following steps:
carbon capture is carried out in the carbon capture absorption tower 2, the generated rich solution sequentially enters a lean rich solution heat exchanger 7, a rich solution reheater 9 and a regeneration tower 10, and the rich solution in the regeneration tower 10 circularly enters a reboiler 11 for heating and then returns to the regeneration tower 10;
the rich solution is regenerated in the regeneration tower 10, and the generated lean solution exchanges heat with the rich solution in the lean and rich solution heat exchanger 7 and then enters the carbon capture absorption tower 2 for reuse;
a stream of flue gas from the boiler 1 is heat exchanged with air in an air preheater 12 to obtain a first stream of flue gas;
another stream of flue gas from the boiler 1 is heat exchanged against the rich liquid in the reboiler 11 to obtain a second stream of flue gas;
the first flue gas material flow and the second flue gas material flow are converged and then exchange heat with the rich liquid in the rich liquid reheater 9, and then enter the carbon capture absorption tower 2 for carbon capture.
In a preferred embodiment, the system further includes an amine recovery heater 8, and the method further includes injecting a portion of the lean solution generated by the regeneration in the regeneration tower 10 into the amine recovery heater 8 to be heated and purified, and then into the carbon capture absorption tower 2 to be reused.
In the present invention, a part of the lean liquid is treated by the amine recovery heater 8 every carbon capture cycle. Preferably, 2 to 6 parts by volume of the lean liquid is injected into the amine recovering heater 8 per 100 parts by volume of the lean liquid produced in the regeneration tower 10.
In a preferred embodiment, the system further comprises a lean liquid cooler 5, the method further comprising: the lean solution after heat exchange with the rich solution in the lean-rich solution heat exchanger 7 is cooled in the lean solution cooler 5 before entering the carbon capture absorption tower 2.
In a preferred embodiment, the absorbent in the carbon capture absorption tower 2 is an alcohol amine absorbent. The present invention will be described in detail below by way of examples, but the scope of the present invention is not limited thereto.
Example 1
The operation of the following embodiment was performed using a system for carbon capture regeneration using the residual heat from flue gas as shown in fig. 1.
Flue gas discharged by a boiler 1 of a coal-fired power plant is subjected to waste heat utilization and desulfurization and denitrification treatment to obtain waste flue gas, the waste flue gas is pressurized and enters from the bottom of a carbon capture absorption tower 2, and alcohol amine absorption liquid (namely CO absorption liquid) 2 Lean solution with lower load) is sprayed from the top of the carbon capture absorption tower 2, the waste flue gas and the alcohol amine absorption solution are directly contacted and reacted, and the alcohol amine absorption solution is changed into CO-containing alcohol amine absorption solution 2 Rich liquor;
the rich solution at about 50 ℃ at the bottom of the carbon capture absorption tower 2 is conveyed into a lean and rich solution heat exchanger 7 through a rich solution pump 6, the rich solution is further heated through a rich solution reheater 9 after exchanging heat with the cold lean solution from a regeneration tower 10 in the lean and rich solution heat exchanger 7, then the rich solution is injected into the regeneration tower 10, high-temperature steam exhausted by a steam-driven draught fan of a coal-fired power plant is injected into a reboiler 11 to exchange heat with the rich solution in the regeneration tower 10, so that the rich solution is subjected to desorption reaction to release CO and release CO 2 The rich solution desorption temperature is 109.7 ℃, and meanwhile, the reboiler 11 provides heat for the regeneration tower 10 to generate steam in the tower, so that high-temperature steam strips CO 2 And delivering the regenerated gas generated at the top of the regeneration tower 10 to a compression unit for purifying liquefied CO 2 ；
Purifying a part (flow ratio is 5%) of the barren solution generated by the regeneration tower 10 by an amine recovery heater 8, introducing the purified barren solution into the carbon capture absorption tower 2, conveying the other part into a barren and rich solution heat exchanger 7, exchanging heat with the rich solution from the carbon capture absorption tower 2, conveying the barren solution to a barren solution cooler 5 for continuous cooling, and conveying the barren solution to the carbon capture absorption tower 2 by a barren solution pump 4 for the next carbon capture cycle;
wherein, the waste heat utilization process of the flue gas that coal fired power plant discharged is: a stream of flue gases from the boiler 1 is heat exchanged with air in said air preheater 12 to obtain a first stream of flue gases;
the other stream of flue gas from the boiler 1 exchanges heat with the lean solution in the amine recovery heater 8, and then exchanges heat with the rich solution in the reboiler 11 to obtain a second flue gas stream;
and the first flue gas material flow and the second flue gas material flow are converged and then subjected to heat exchange with the rich liquid in the rich liquid reheater 9, and then are conveyed to the carbon capture absorption tower 2 through a carbon capture induced draft fan 3 for carbon capture.
The detection shows that the carbon dioxide content in the flue gas at the inlet of the carbon capture absorption tower 2 is 14.28%, and the temperature is 41.7 ℃. Through measurement and calculation, the concentration of carbon dioxide at the outlet of the absorption tower is 2.47%, and the capture rate of carbon dioxide is 82.7%. The energy consumption (the energy consumption of the amine recovery heater 8 and the regeneration energy consumption) in the carbon capture unit is 2.53GJ/tCO 2 The regeneration energy consumption is 2.53GJ/tCO 2 。
Example 2
The method of the embodiment 1 is implemented, except that the flue gas waste heat is not used in the amine recovery heater 8, specifically, the flue gas waste heat utilization process of the coal-fired power plant is as follows: a stream of flue gases from the boiler 1 is heat exchanged with air in said air preheater 12 to obtain a first stream of flue gases;
exchanging heat between the other flue gas from the boiler 1 and the rich liquid in the reboiler 11 to obtain a second flue gas material flow;
the first flue gas flow and the second flue gas flow are converged and then exchange heat with the rich solution in the rich solution reheater 9, and then are injected into the carbon capture absorption tower 2 for carbon capture.
The detection shows that the content of carbon dioxide in the flue gas at the inlet of the carbon capturing and absorbing tower 2 is 14.62%, and the temperature is 40.8 ℃. Through measurement and calculation, the concentration of carbon dioxide at the outlet of the absorption tower is 2.63%, and the capture rate of carbon dioxide is 82.1%. The energy consumption (energy consumption of the amine recovery heater 8 and regeneration energy consumption) in the carbon capture unit is 2.62GJ/tCO 2 The regeneration energy consumption is 2.54GJ/tCO 2 。
Comparative example 1
The method is carried out according to the method of example 1, except that the flue gas generated by the coal-fired power plant is subjected to heat exchange treatment by the air preheater 12, then is subjected to desulfurization and denitrification treatment, and is injected into the carbon capture absorption tower 2 to be subjected to carbon capture treatment, that is, the flue gas waste heat is not utilized in the carbon capture unit.
The detection shows that the content of carbon dioxide in the flue gas at the inlet of the carbon capturing and absorbing tower 2 is 14.52%, and the temperature is 41.2 ℃. Through measurement and calculation, the concentration of carbon dioxide at the outlet of the carbon capture absorption tower 2 is 2.58%, and the capture rate of carbon dioxide is 82.2%. The energy consumption (the energy consumption of the amine recovery heater 8 and the regeneration energy consumption) of the traditional carbon capture absorption unit is 2.94GJ/tCO 2 The regeneration energy consumption is 2.89GJ/tCO 2 。
Comparing the embodiment 1 with the embodiment 2, it can be seen that the flue gas waste heat is utilized in three stages, so that the flue gas waste heat can be utilized more fully, the heat loss is reduced, and the energy utilization rate is improved. Comparing the examples 1-2 with the comparative example 1, it can be seen that the energy consumption of the carbon capture unit can be reduced by about 10.9-13.9% by utilizing the flue gas waste heat of the coal-fired power plant.
It should be noted that the flue gas in example 2 is not used by the amine recovery heater, but the regeneration energy consumption in example 1 and example 2 is equivalent, and it is assumed that there is a limit to the load value for heating the rich liquid by the flue gas waste heat.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. The system for using the flue gas waste heat for carbon capture regeneration is characterized by comprising a carbon capture absorption tower (2), a lean-rich liquid heat exchanger (7), a rich liquid reheater (9), a regeneration tower (10), a reboiler (11) and an air preheater (12),
rich liquid generated in the carbon capture absorption tower (2) sequentially enters the lean rich liquid heat exchanger (7), the rich liquid reheater (9) and the regeneration tower (10), and rich liquid in the regeneration tower (10) is circularly fed into the reboiler (11) for heating and then returns to the regeneration tower (10);
the barren solution generated in the regeneration tower (10) exchanges heat with the rich solution in the barren and rich solution heat exchanger (7), and then enters the carbon capture absorption tower (2) for reuse;
exchanging heat between a stream of flue gas from a boiler (1) and air in said air preheater (12) to obtain a first stream of flue gas;
exchanging heat of another flue gas from the boiler (1) with the rich liquid in the reboiler (11) to obtain a second flue gas stream;
and the first flue gas flow and the second flue gas flow are converged and then exchange heat with the rich solution in the rich solution reheater (9), and then enter the carbon capture absorption tower (2) for carbon capture.
2. The system according to claim 1, further comprising an amine recovery heater (8) for heating and purifying a portion of the lean liquid produced in the regeneration tower (10).
3. A system according to claim 2, characterized in that another flue gas from the boiler (1) is heat exchanged with the lean liquor in the amine recovery heater (8) before entering the reboiler (11).
4. The system according to any one of claims 1-3, further comprising a lean liquor cooler (5), wherein the lean liquor after heat exchange with rich liquor in the lean-rich liquor heat exchanger (7) is cooled in the lean liquor cooler (5) before entering the carbon capture absorption tower (2).
5. A method for carbon capture regeneration by flue gas waste heat, the method being implemented in a system comprising a carbon capture absorption tower (2), a lean-rich liquid heat exchanger (7), a rich liquid reheater (9), a regeneration tower (10), a reboiler (11), and an air preheater (12), the method comprising:
performing carbon capture in the carbon capture absorption tower (2), sequentially feeding the generated rich solution into the lean-rich solution heat exchanger (7), the rich solution reheater (9) and the regeneration tower (10), and circulating the rich solution in the regeneration tower (10) into the reboiler (11) for heating and then returning to the regeneration tower (10);
the rich solution is regenerated in the regeneration tower (10), and the generated lean solution exchanges heat with the rich solution in the lean-rich solution heat exchanger (7) and then enters the carbon capture absorption tower (2) for reuse;
exchanging heat between a stream of flue gas from a boiler (1) and air in said air preheater (12) to obtain a first stream of flue gas;
exchanging heat of another stream of flue gas from the boiler (1) with the rich liquid in the reboiler (11) to obtain a second stream of flue gas;
and the first flue gas flow and the second flue gas flow are converged and then exchange heat with the rich solution in the rich solution reheater (9), and then enter the carbon capture absorption tower (2) for carbon capture.
6. The method according to claim 5, wherein the system further comprises an amine recovery heater (8), and the method further comprises injecting a part of the lean solution generated by the regeneration in the regeneration tower (10) into the amine recovery heater (8) for heating and purification, and then into the carbon capture absorption tower (2) for reuse.
7. The method according to claim 6, characterized in that 2 to 6 parts by volume of the lean liquid is injected into the amine recovery heater (8) per 100 parts by volume of the lean liquid produced in the regeneration tower (10).
8. A method according to claim 6 or 7, characterized in that another flue gas from the boiler (1) is heat exchanged with the lean liquor in the amine recovery heater (8) before entering the reboiler (11).
9. The method according to any one of claims 5-7, wherein the system further comprises a lean liquid cooler (5), the method further comprising: the barren solution after exchanging heat with the rich solution in the barren solution and rich solution heat exchanger (7) enters the barren solution cooler (5) for cooling before entering the carbon capture absorption tower (2).
10. The method according to any one of claims 5 to 7, wherein the absorbent in the carbon capture absorption tower (2) is an alcohol amine absorption liquid.
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