CN115634561A - Carbon dioxide capturing and washing device and method for thermal power plant - Google Patents
Carbon dioxide capturing and washing device and method for thermal power plant Download PDFInfo
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- CN115634561A CN115634561A CN202211017162.7A CN202211017162A CN115634561A CN 115634561 A CN115634561 A CN 115634561A CN 202211017162 A CN202211017162 A CN 202211017162A CN 115634561 A CN115634561 A CN 115634561A
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 188
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 94
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 94
- 238000005406 washing Methods 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000010521 absorption reaction Methods 0.000 claims abstract description 70
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- 238000011069 regeneration method Methods 0.000 claims description 86
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 44
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 38
- 239000003546 flue gas Substances 0.000 claims description 38
- 239000007789 gas Substances 0.000 claims description 30
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 claims description 28
- 239000007788 liquid Substances 0.000 claims description 24
- 238000011084 recovery Methods 0.000 claims description 19
- 150000001412 amines Chemical class 0.000 claims description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 16
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- 239000002253 acid Substances 0.000 claims description 6
- 125000004122 cyclic group Chemical group 0.000 claims description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 3
- 238000004458 analytical method Methods 0.000 claims description 3
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- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention discloses a device and a method for capturing and washing carbon dioxide in a thermal power plant. The method includes operating a carbon dioxide capture system to absorb carbon dioxide from an exhaust gas of a power plant with an absorbent solution and release the absorbed carbon dioxide from the absorbent solution to form a carbon dioxide gas stream; delivering the carbon dioxide gas stream to a carbon dioxide compression system that compresses and cools the carbon dioxide gas stream; an external heat cycle system is used for heating the reboiler. The device and the method for capturing and washing the carbon dioxide in the thermal power plant improve the absorption efficiency and reduce the comprehensive energy consumption.
Description
Technical Field
The invention relates to the field of thermal power generation, in particular to a carbon dioxide capturing and washing device and method for a thermal power plant.
Background
At present, great progress is made in the aspects of energy saving and consumption reduction of a carbon dioxide capturing and purifying system in China, great progress is made in the aspects of single technology energy saving, process adjustment and integration and the like, a batch of demonstration projects are successively established, and good economic benefits and social benefits are obtained. The reboiler needs to provide a large amount of steam, and in order for the reboiler to generate a large amount of steam, a large amount of steam needs to be supplied to the reboiler from a turbine extraction system or a turbine exhaust system. However, this reduces the output of the turbine by an amount corresponding to the steam supplied from the steam extraction system, resulting in a reduction in turbine efficiency. The operation of the carbon dioxide capture and purification system mainly adopts a mode of block management, the overall coordination and optimization are lacked, and the benefit of the system energy still exists in unreasonable places.
The following problems exist in the industrial chemical absorption process:
(1) The energy consumption of the trapping process is large. The operation temperature of the absorption tower is 40-65 ℃, which means that the temperature of the flue gas must be reduced before entering the absorption tower; the operation temperature of the regeneration tower is 100-120 ℃; the outlet flue gas needs to be re-warmed before entering the atmosphere.
(2) Absorbent inefficiency absorbent for CO in a cyclic process 2 The absorption efficiency is not high, the loss in the operation process is large, the absorbent solution is oxidized and lost, and corrosion and foaming phenomena are generated on the system.
(3)CO 2 High recovery cost and CO recovery by using the existing process 2 The cost is about 500-600 yuan per ton, the recovery cost is high, and the cost of the power plant is increased by 1/3.CO 2 2 The goal of capture separation is to separate CO 2 The recovery process is economically feasible, which puts severe demands on the simulated optimization improvement of the separation process.
Disclosure of Invention
The invention aims to provide a carbon dioxide capturing and washing device and a carbon dioxide capturing and washing method for a thermal power plant, which improve the absorption efficiency and reduce the comprehensive energy consumption.
In one aspect of the invention, a thermal power plant carbon dioxide capture scrubbing apparatus is presented. According to an embodiment of the invention, the apparatus comprises:
the system comprises a carbon dioxide capturing system and a regeneration tower, wherein the carbon dioxide capturing system comprises an absorption tower and the regeneration tower, the absorption tower removes carbon dioxide in flue gas generated by a thermal power plant through an absorbent, and the regeneration tower is used for receiving an absorbent rich solution in the absorption tower and carrying out stripping desorption;
the carbon dioxide compression system comprises a compressor and a carbon dioxide storage tank, the compressor is used for compressing the carbon dioxide gas discharged from the top of the regeneration tower, and the carbon dioxide storage tank is used for storing the carbon dioxide gas compressed by the compressor;
and the external heat circulation system comprises an air preheater and a reboiler, the air preheater is respectively connected with the absorption tower and the reboiler, and the reboiler is connected with the regeneration tower.
In addition, the thermal power plant carbon dioxide capturing and washing device according to the above embodiment of the present invention may further have the following additional technical features:
in some embodiments of the invention, the carbon dioxide capture system further comprises:
the temperature reduction device is connected with the absorption tower, the temperature reduction device is connected with the desulfurization device, and the desulfurization device is connected with the denitration device;
the absorption tower comprises a rich solution pump connected with the bottom of the absorption tower, a lean and rich solution heat exchanger connected with the rich solution pump, a lean and rich solution heat exchanger connected with the top of the regeneration tower, and a lean solution pump connected between the bottoms of the regeneration tower;
the barren liquor pump is connected with the tower bottom of the regeneration tower, the barren liquor pump is connected with a barren and rich liquor heat exchanger, the barren and rich liquor heat exchanger is respectively connected with a barren liquor cooler and an amine recovery heater, the barren liquor cooler is connected with an active carbon filtering device, and the active carbon filtering device is connected with the tower bottom of the absorption tower;
and the condenser is connected with the tower bottom of the regeneration tower, the condenser is connected with the reflux tank, and the reflux tank is connected with the tower bottom of the regeneration tower.
In some embodiments of the present invention, the carbon dioxide compression system further includes a backup cooler connected to the return tank, the backup cooler is connected to a cooling tower, the cooling tower is connected to three intercoolers, the intercoolers are respectively connected to compressors, the compressors are driven by a motor, and the intercoolers are connected to the carbon dioxide storage tank.
In some embodiments of the invention, a condensed water heat exchanger is arranged in the flue of the air preheater.
In another aspect of the invention, a method for carbon dioxide capture scrubbing in a thermal power plant is provided. According to an embodiment of the invention, the method comprises the following steps:
(1) The flue gas generated by the coal-fired boiler firstly enters an air preheater, then enters an absorption tower after denitration and desulfurization, and flows from bottom to top in the absorption tower to form countercurrent contact with an absorbent entering the absorption tower from the upper part, so that CO is generated 2 Removing, and discharging the purified decarbonized flue gas from the top of the absorption tower;
(2) Heating the 56 ℃ absorbent rich solution flowing out from the bottom of the absorption tower to 98 ℃ and then entering a regeneration tower for stripping desorption;
(3) Desorption of CO 2 The lean solution of the absorbent flows out from the bottom of the regeneration tower, is subjected to heat exchange by a lean-rich solution heat exchanger, is sent to a lean solution cooler, and enters an absorption tower for cyclic utilization after being cooled;
(4 CO desorbed in the regeneration column 2 The temperature is 100-120 ℃, a condenser and a reflux tank behind the regeneration tower recover a large amount of saturated water and amine solution with extremely low concentration, liquid water separated from the reflux tank is conveyed to the top of the regeneration tower for spraying, the temperature at the top of the tower is reduced, and the temperature gradient in the regeneration tower is ensured;
(5) Part of the CO desorbed in the regeneration column by stripping 2 Introducing into reboiler to make CO therein 2 Further desorbing and returning to the regeneration tower;
(6) Carbon dioxide gas discharged from the top of the regeneration tower enters a cooling tower through a blower under the conditions of normal pressure and temperature lower than 40 ℃ to wash away impurities such as solvents brought in the flue gas, then the dew point of the flue gas is reduced by low-temperature liquid ammonia through an intercooler, the gas enters a compressor, the compressor adopts three-stage compression, the gas compressed at each stage enters the intercooler to be cooled and enters the next-stage compression, and the gas is compressed and cooled at three stages and is stored in carbon dioxide through a carbon dioxide storage tank.
In addition, the method for capturing and washing carbon dioxide in a thermal power plant according to the above embodiment of the present invention may further have the following additional technical features:
in some embodiments of the present invention, in step (1), a condensed water heat exchanger is arranged in a flue of the air preheater, and the condensed water heat exchanger reduces the temperature of the flue gas to 100 to 120 ℃ which is higher than the acid dew point temperature of the flue gas, and is used for heating the reboiler;
a water spraying temperature reducing device is arranged in front of the absorption tower, and when the temperature of the flue gas is over-high due to fluctuation of working conditions, the water spraying temperature reducing device is started to reduce the temperature of the flue gas to below 50 ℃;
the absorption tower is divided into two sections, the lower section absorbs acid gas, the upper section reduces the ethanolamine steam content in the flue gas through water washing, washing water recycling utilizes the ethanolamine in the washing water to be continuously enriched, a part of washing water is merged into rich liquid to be sent to the regeneration tower for regeneration, the lost washing water is kept through regeneration gas condensate water, and water balance is guaranteed.
In some embodiments of the invention, in the step (2), the 56 ℃ absorbent rich solution flowing out from the bottom of the absorption tower is heated to 98 ℃ by a rich solution pump to a lean and rich solution heat exchanger and enters a regeneration tower for stripping desorption.
In some embodiments of the present invention, in step (3), the absorbent lean solution flowing out from the bottom of the regeneration tower enters the lean-rich solution heat exchanger through the lean solution pump, so that the temperature of the absorbent lean solution is reduced to 56 ℃, and then is reduced to 40 ℃ through the lean solution cooler and enters the absorption tower;
an activated carbon filter is arranged on a barren liquor pipeline entering the absorption tower in a bypass way, and the proportion of the solution passing through the activated carbon filter is adjusted according to the pollution degree obtained by solution analysis to keep the solution clean;
an amine recovery heater is arranged between the rich liquor heat exchanger and the lean liquor cooler, the lean liquor cooler is operated intermittently, heat stable salt in the amine recovery heater is heated and decomposed to generate ethanolamine solution, the ethanolamine solution is recycled, and non-renewable degradation products are discharged from the amine recovery heater and are subjected to harmless treatment.
In some embodiments of the invention, the absorption tower and the regeneration tower adopt a packed tower.
In some embodiments of the invention, in the step (6), the carbon dioxide is pressurized to 2.5-3.0 MPa in three stages and is liquefied by cooling the carbon dioxide to a temperature below-8 ℃ with an intercooler.
Compared with the prior art, the invention has the beneficial effects that:
1) In the invention, the design of the absorption tower and the regeneration tower adopts high-efficiency packing equipment, so that the heat and mass transfer efficiency can be greatly improved, the irreversible degree of the process is reduced, and a good economic effect is obtained.
2) Compared with other recovery devices, the carbon dioxide capturing and washing device and the carbon dioxide capturing and washing method for the thermal power plant can reasonably recycle heat energy and recover low-level heat energy, improve the heat energy utilization rate of the system, reduce energy consumption and play a role in saving energy.
3) Compared with the prior art that heat is obtained from a steam turbine, the device and the method for capturing and washing the carbon dioxide in the thermal power plant adopt the waste heat of the air preheater to heat the reboiler, avoid the steam extraction quantity of the reboiler of a regeneration tower which is supplied to the carbon dioxide capturing and washing equipment from the steam turbine, and better utilize the waste heat of the air preheater with low energy cost. The present invention does not affect the efficiency and output reduction of the steam turbine, and at the same time, the air preheater is connected to the reboiler regardless of the variation in the amount of heating steam supplied therefrom, minimizes the variation in the temperature and pressure of steam generated from the reboiler, and stably performs the reaction of separating carbon dioxide from the absorbent in the regeneration tower.
4) The medium-pressure equipment for mainly utilizing liquefied gas carbon dioxide has the advantages of low investment, low comprehensive energy consumption, low danger and high safety.
5) The method utilizing the chemical absorption method principle can be used for capturing and washing the carbon dioxide in the thermal power plant, and avoids the limitation of the carbon dioxide capturing equipment.
Drawings
FIG. 1 is a schematic configuration diagram of a carbon dioxide capturing and washing apparatus of a thermal power plant in example 1 of the present invention;
in the figure, 1, a boiler, 2, an air preheater, 3, a denitration device, 4, a desulfurization device, 5, a temperature reduction device, 6, an absorption tower, 7, a rich liquid pump, 8, a lean and rich liquid heat exchanger, 9, a lean liquid cooler, 10, an activated carbon filtering device, 11, a lean liquid pump, 12, a regeneration tower, 13, a reboiler, 14, a condenser, 15, a reflux tank, 16, an amine recovery heater, 17, a standby cooler, 18, a cooling tower, 19, an intercooler, 20, a compressor, 21, a motor, 22 and a carbon dioxide storage tank.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Example 1
Referring to fig. 1, the carbon dioxide capture washing apparatus for a thermal power plant includes: a thermal power plant for generating electricity, the thermal power plant comprising: a boiler 1 for generating steam by burning fossil fuel.
The carbon dioxide capturing system comprises an absorption tower 6 and a regeneration tower 12, wherein the absorption tower 6 removes carbon dioxide in the flue gas generated by the boiler 1 through an absorbent, and the regeneration tower 12 is used for receiving an absorbent rich solution in the absorption tower 6 and carrying out stripping desorption; the absorption tower 6 and the regeneration tower 12 adopt a packed tower which has small pressure drop and is not easy to foam. The filler has large void ratio, gas-liquid two phases can uniformly pass through the filler, the pressure drop is low, and the flow rate is high; the solution can form a stable liquid film on the surface of the pore plate, the wetting rate is high, and the mass transfer efficiency is higher; has good wetting property and self-distribution capability, uniform gas-liquid distribution and almost no amplification effect.
The carbon dioxide capture system also comprises a temperature reduction device 5 connected with the absorption tower 6, wherein the temperature reduction device 5 is connected with the desulfurization device 4, and the desulfurization device 4 is connected with the denitration device 3; the rich liquor pump 7 is connected with the bottom of the absorption tower 6, the rich liquor pump 7 is connected with the lean and rich liquor heat exchanger 8, the lean and rich liquor heat exchanger 8 is connected with the top of the regeneration tower 12, and the lean liquor pump 11 is connected between the bottoms of the regeneration tower 12; a barren liquor pump 11 connected with the tower bottom of the regeneration tower 12, wherein the barren liquor pump 11 is connected with a barren and rich liquor heat exchanger 8, the barren and rich liquor heat exchanger 8 is respectively connected with a barren liquor cooler 9 and an amine recovery heater 16, the barren liquor cooler 9 is connected with an active carbon filtering device 10, and the active carbon filtering device 10 is connected with the tower bottom of the absorption tower 6; and the condenser 14 is connected with the bottom of the regeneration tower 12, the condenser 14 is connected with the reflux tank 15, and the reflux tank 15 is connected with the bottom of the regeneration tower 12.
The carbon dioxide compression system comprises a compressor 20 and a carbon dioxide storage tank 22, wherein the compressor 20 is used for compressing the carbon dioxide gas discharged from the top of the regeneration tower 12, and the carbon dioxide storage tank 22 is used for storing the carbon dioxide gas compressed by the compressor 20; the cooling tower 18 is connected with three intercoolers 19, the intercoolers 19 are respectively connected with a compressor 20, the compressor 20 is driven by a motor 21 to work, and the intercooler 19 is connected with a carbon dioxide storage tank 22.
And the external heat circulation system comprises an air preheater 2 and a reboiler 13, wherein the air preheater 2 is respectively connected with the absorption tower 6 and the reboiler 13, and the reboiler 13 is connected with the regeneration tower 12. The flue of air preheater 2 is internally provided with a condensed water heat exchanger, and the smoke inlet of air preheater 2 is also provided with a denitration device 3.
A heating system is also included for supplying steam extracted from the waste heat of the air preheater 2 to the reboiler 13.
The working principle is as follows: operating the carbon dioxide capture system to absorb carbon dioxide from the exhaust gas of the power plant with the absorbent solution and to release the absorbed carbon dioxide from the absorbent solution to form a carbon dioxide gas stream; delivering the carbon dioxide gas stream to a carbon dioxide compression system that compresses and cools the carbon dioxide gas stream; an external heat cycle system is used for heating the reboiler 13.
Example 2
The invention provides a method for capturing and washing carbon dioxide in a thermal power plant, which comprises the following steps:
(1) The flue gas generated by the coal-fired boiler firstly enters an air preheater, then enters an absorption tower after denitration and desulfurization, and flows from bottom to top in the absorption tower to form countercurrent contact with an absorbent entering the absorption tower from the upper part, so that CO is generated 2 And removing the decarbonized flue gas, and discharging the purified decarbonized flue gas from the top of the absorption tower.
A condensed water heat exchanger is arranged in a flue of the air preheater, reduces the temperature of the flue gas to 100-120 ℃ and is higher than the acid dew point temperature of the flue gas, and is used for heating a reboiler.
A water spraying temperature reduction device is arranged between the absorption tower and the desulfurization device, and when the temperature of the flue gas is over-temperature under the fluctuation of working conditions, the water spraying temperature reduction device is started to reduce the temperature of the flue gas to below 50 ℃; the temperature of flue gas generated by the coal-fired boiler is generally 160 ℃, the temperature of the flue gas is reduced to 50 ℃, the flue gas enters the absorption tower to be subjected to carbon dioxide separation, the heat energy can be used in reaction heat required by desorption of the absorbent in the regeneration process by utilizing the heat energy, and a heat exchanger is arranged at the flue gas inlet of the absorption tower and the bottom of the regeneration tower to perform heat exchange, so that the heat energy utilization rate of the system is improved.
Ethanolamine has higher vapor pressure, in order to reduce the ethanolamine steam and cause absorbent loss along with the flue gas brings out, the absorption tower divides into two sections, and the hypomere carries out the acid gas to absorb, and the upper segment is through washing, reduces the ethanolamine steam content in the flue gas, and the washing water cyclic utilization is along with the continuous enrichment of ethanolamine in the washing water, merges some washing water into the pregnant solution and sends the regenerator column into and regenerates, and the washing water of loss is kept through regeneration gas condensate water, has guaranteed water balance.
(2) The 56 ℃ absorbent rich solution flowing out from the bottom of the absorption tower is pumped to the lean and rich solution heat exchanger through the rich solution pump, heated to 98 ℃ and then enters the regeneration tower for stripping desorption, so that the consumption of steam during rich solution regeneration is reduced, the rich solution is heated by using the waste heat of the regenerated absorbent lean solution, and the aim of cooling the regenerated solution is fulfilled.
(3) Desorption of CO 2 And the lean solution of the absorbent flows out from the bottom of the regeneration tower, is subjected to heat exchange by a lean-rich solution heat exchanger, is sent to a lean solution cooler, and enters the absorption tower for cyclic utilization after being cooled.
The absorbent barren solution flowing out of the bottom of the regeneration tower enters a barren and rich solution heat exchanger through a barren solution pump, the temperature of the absorbent barren solution is reduced to 56 ℃, then the temperature of the absorbent barren solution is reduced to 40 ℃ through a barren solution cooler, the absorbent barren solution enters an absorption tower, and cooling water used in the process takes away a part of heat energy for use elsewhere in the system or for use as heat energy required by another system; the lean liquid cooler reduces the lean liquid from 56 ℃ to 40 ℃, the condenser at the top of the regeneration tower reduces the regeneration gas from 98 ℃ to 40 ℃, the heat energy carried away by the cooling water is large in quantity and low in temperature level, the heat energy is low in temperature level, the process utilization value is not large, and the lean liquid cooler is used as living heating or as heating boiler feed water to reduce energy consumption and play a role in saving energy.
The activated carbon filter is arranged on a barren liquor pipeline entering the absorption tower in a bypass mode, the proportion of the solution passing through the activated carbon filter is adjusted according to the pollution degree obtained by solution analysis, the solution is kept clean, about 10% -15% of barren liquor is filtered through the activated carbon filter, and solid impurities such as rust and the like in the absorbent can be removed.
And an amine recovery heater is arranged between the rich liquor heat exchanger and the lean liquor cooler, the operation is carried out intermittently, heat-stable salt in the amine recovery heater is heated and decomposed to generate ethanolamine solution, the ethanolamine solution is recycled, and non-renewable degradation products are discharged from the amine recovery heater and are subjected to harmless treatment. When necessary, part of the lean solution is sent to an amine recovery heater, added with an alkali solution, and recovered by steam heating regeneration.
The absorption tower and the regeneration tower adopt a packed tower which has small pressure drop and is not easy to foam. The filler has large void ratio, gas-liquid two phases can uniformly pass through the filler, the pressure drop is low, and the flow rate is high; the solution can form a stable liquid film on the surface of the pore plate, the wetting rate is high, and the mass transfer efficiency is higher; has good wetting property and self-distribution capability, uniform gas-liquid distribution and almost no amplification effect.
(4) CO desorbed in a regeneration column 2 The temperature is 100-120 ℃, a condenser and a reflux tank behind the regeneration tower recover a large amount of saturated water and amine solution with extremely low concentration, and the water and the solution maintain the water balance of the regeneration tower system and the concentration of the absorbent solution to be stable; the liquid water separated from the reflux tank is conveyed to the top of the regeneration tower again for spraying, so that the temperature at the top of the tower is reduced, the temperature gradient in the regeneration tower is ensured, and the water balance of the system is maintained.
(5) Part of the CO desorbed in the regeneration column by stripping 2 Introducing into reboiler to make CO therein 2 Returning to the regeneration tower after further desorption; the design of the reboiler adopts a vertical natural differential pressure reboiler to regenerate the solutionThe higher high position in the tower enters the bottom of the reboiler, the heated and raised gaseous mixture enters the bottom of the regeneration tower, the regenerated solution gas flows out from the high position of the regeneration tower and enters the tower from the low position, and the height difference is the power for promoting the solution to naturally flow in the reboiler. The flow arrangement not only keeps the compact structure and high heat transfer coefficient of the vertical reboiler, but also avoids the unstable problem of thermosyphon.
(6) Under the conditions that the temperature of a mixture of carbon dioxide gas and steam discharged from the top of the regeneration tower is normal pressure and lower than 40 ℃, the mixture is subjected to low-temperature liquid ammonia by an intercooler to reduce the dew point of flue gas, the gas enters a compressor, three-stage compression is adopted by the compressor, the gas after each stage of compression enters the intercooler to be cooled and then enters the next stage of compression, the carbon dioxide is pressurized to 2.5-3.0 MPa by three stages, the temperature is cooled to below-8 ℃ by the intercooler to be liquefied, and the carbon dioxide is stored by a carbon dioxide storage tank.
The foregoing is merely exemplary and illustrative of the present invention and various modifications, additions and substitutions may be made by those skilled in the art to the specific embodiments described without departing from the scope of the present invention as defined in the accompanying claims.
Claims (10)
1. Thermal power plant carbon dioxide capture washing device, its characterized in that includes:
the system comprises a carbon dioxide capturing system and a regeneration tower, wherein the carbon dioxide capturing system comprises an absorption tower and the regeneration tower, the absorption tower removes carbon dioxide in flue gas generated by a thermal power plant through an absorbent, and the regeneration tower is used for receiving an absorbent rich solution in the absorption tower and carrying out stripping desorption;
the carbon dioxide compression system comprises a compressor and a carbon dioxide storage tank, wherein the compressor is used for compressing carbon dioxide gas discharged from the top of the regeneration tower, and the carbon dioxide storage tank is used for storing the carbon dioxide gas compressed by the compressor;
and the external heat circulation system comprises an air preheater and a reboiler, the air preheater is respectively connected with the absorption tower and the reboiler, and the reboiler is connected with the regeneration tower.
2. The thermal power plant carbon dioxide capture scrubbing apparatus as claimed in claim 1, wherein said carbon dioxide capture system further comprises:
the temperature reduction device is connected with the absorption tower, the temperature reduction device is connected with the desulfurization device, and the desulfurization device is connected with the denitration device;
the absorption tower comprises a rich solution pump connected with the bottom of the absorption tower, a lean and rich solution heat exchanger connected with the rich solution pump, a lean and rich solution heat exchanger connected with the top of the regeneration tower, and a lean solution pump connected between the bottoms of the regeneration tower;
the lean liquid pump is connected with the tower bottom of the regeneration tower, the lean liquid pump is connected with the lean-rich liquid heat exchanger, the lean-rich liquid heat exchanger is respectively connected with a lean liquid cooler and an amine recovery heater, the lean liquid cooler is connected with an active carbon filtering device, and the active carbon filtering device is connected with the tower bottom of the absorption tower;
and the condenser is connected with the tower bottom of the regeneration tower, the condenser is connected with the reflux tank, and the reflux tank is connected with the tower bottom of the regeneration tower.
3. The thermal power plant carbon dioxide capture washing device as recited in claim 2, wherein the carbon dioxide compression system further comprises a backup cooler connected to the return tank, the backup cooler is connected to a cooling tower, the cooling tower is connected to three intercoolers, the intercoolers are respectively connected to compressors, the compressors are driven by a motor, and the intercoolers are connected to the carbon dioxide storage tank.
4. The thermal power plant carbon dioxide capture scrubbing apparatus of claim 2, wherein: and a condensed water heat exchanger is arranged in a lower flue of the air preheater.
5. A method for carbon dioxide capture scrubbing in a thermal power plant, comprising the steps of:
(1) The flue gas generated by the coal-fired boiler is firstlyEntering an air preheater, then entering an absorption tower after denitration and desulfurization, wherein flue gas flows from bottom to top in the absorption tower and forms countercurrent contact with an absorbent entering the absorption tower from the upper part to ensure that CO is absorbed by the absorbent 2 Removing, and discharging the purified decarbonized flue gas from the top of the absorption tower;
(2) Heating the 56 ℃ absorbent rich solution flowing out from the bottom of the absorption tower to 98 ℃ and then entering a regeneration tower for stripping desorption;
(3) Desorption of CO 2 The lean solution of the absorbent flows out from the bottom of the regeneration tower, is subjected to heat exchange by a lean-rich solution heat exchanger, is sent to a lean solution cooler, and enters an absorption tower for cyclic utilization after being cooled;
(4) CO desorbed in a regeneration column 2 The temperature is 100-120 ℃, a condenser and a reflux tank behind the regeneration tower recover a large amount of saturated water and amine solution with extremely low concentration, liquid water separated from the reflux tank is conveyed to the top of the regeneration tower for spraying, the temperature at the top of the tower is reduced, and the temperature gradient in the regeneration tower is ensured;
(5) Part of the CO desorbed in the regeneration column by stripping 2 Introducing into reboiler to make CO therein 2 Further desorbing and returning to the regeneration tower;
(6) Carbon dioxide gas discharged from the top of the regeneration tower enters a cooling tower through a blower under the conditions of normal pressure and temperature lower than 40 ℃ to wash away impurities such as solvents brought in the flue gas, then the dew point of the flue gas is reduced by low-temperature liquid ammonia through an intercooler, the gas enters a compressor, the compressor adopts three-stage compression, the gas compressed at each stage enters the intercooler to be cooled and enters the next-stage compression, and the gas is compressed and cooled at three stages and is stored in carbon dioxide through a carbon dioxide storage tank.
6. The method of thermal power plant carbon dioxide capture scrubbing of claim 5, wherein: in the step (1), a condensed water heat exchanger is arranged in a flue of the air preheater, and the condensed water heat exchanger reduces the temperature of the flue gas to 100-120 ℃ and is higher than the acid dew point temperature of the flue gas, and is used for heating a reboiler;
a water spraying temperature reducing device is arranged in front of the absorption tower, and when the temperature of the flue gas is over-high due to fluctuation of working conditions, the water spraying temperature reducing device is started to reduce the temperature of the flue gas to below 50 ℃;
the absorption tower is divided into two sections, the lower section absorbs acid gas, the upper section reduces the ethanolamine steam content in the flue gas through water washing, washing water recycling utilizes the ethanolamine in the washing water to be continuously enriched, a part of washing water is merged into rich liquid to be sent to the regeneration tower for regeneration, the lost washing water is kept through regeneration gas condensate water, and water balance is guaranteed.
7. The method for thermal power plant carbon dioxide capture scrubbing of claim 5, wherein: in the step (2), the 56 ℃ absorbent rich solution flowing out from the bottom of the absorption tower is pumped to a lean rich solution heat exchanger through a rich solution pump, heated to 98 ℃ and then enters a regeneration tower for stripping desorption.
8. The method for thermal power plant carbon dioxide capture scrubbing of claim 5, wherein: the step (3) is specifically that the absorbent barren solution flowing out from the bottom of the regeneration tower enters a barren and rich solution heat exchanger through a barren solution pump, so that the temperature of the absorbent barren solution is reduced to 56 ℃, and then is reduced to 40 ℃ through a barren solution cooler and enters the absorption tower;
an activated carbon filter is arranged on a barren liquor pipeline entering the absorption tower in a bypass way, and the proportion of the solution passing through the activated carbon filter is adjusted according to the pollution degree obtained by solution analysis to keep the solution clean;
an amine recovery heater is arranged between the rich liquor heat exchanger and the lean liquor cooler, the lean liquor cooler is operated intermittently, heat stable salt in the amine recovery heater is heated and decomposed to generate ethanolamine solution, the ethanolamine solution is recycled, and non-renewable degradation products are discharged from the amine recovery heater and are subjected to harmless treatment.
9. The method of thermal power plant carbon dioxide capture scrubbing of claim 5, wherein: the absorption tower and the regeneration tower adopt a packed tower.
10. The method of thermal power plant carbon dioxide capture scrubbing of claim 5, wherein: in the step (6), the carbon dioxide is pressurized to 2.5-3.0 MPa in three stages, and is cooled to below-8 ℃ by an intercooler for liquefaction.
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