CN117679904A - Flue gas carbon dioxide recovery method and system - Google Patents
Flue gas carbon dioxide recovery method and system Download PDFInfo
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- CN117679904A CN117679904A CN202311653076.XA CN202311653076A CN117679904A CN 117679904 A CN117679904 A CN 117679904A CN 202311653076 A CN202311653076 A CN 202311653076A CN 117679904 A CN117679904 A CN 117679904A
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 128
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 97
- 239000003546 flue gas Substances 0.000 title claims abstract description 97
- 238000000034 method Methods 0.000 title claims abstract description 67
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 66
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 66
- 238000011084 recovery Methods 0.000 title claims abstract description 15
- 238000001179 sorption measurement Methods 0.000 claims abstract description 226
- 239000007789 gas Substances 0.000 claims abstract description 169
- 239000003463 adsorbent Substances 0.000 claims abstract description 83
- 230000008929 regeneration Effects 0.000 claims abstract description 26
- 238000011069 regeneration method Methods 0.000 claims abstract description 26
- 238000000926 separation method Methods 0.000 claims abstract description 13
- 230000001172 regenerating effect Effects 0.000 claims abstract description 8
- 238000003860 storage Methods 0.000 claims description 66
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 28
- 230000008569 process Effects 0.000 claims description 25
- 238000003795 desorption Methods 0.000 claims description 13
- 238000001816 cooling Methods 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 7
- 239000002808 molecular sieve Substances 0.000 claims description 5
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 239000000741 silica gel Substances 0.000 claims description 4
- 229910002027 silica gel Inorganic materials 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- 229910000831 Steel Inorganic materials 0.000 claims description 3
- 239000004568 cement Substances 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 239000010959 steel Substances 0.000 claims description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 2
- 238000010168 coupling process Methods 0.000 abstract description 3
- 238000005265 energy consumption Methods 0.000 description 13
- 238000005262 decarbonization Methods 0.000 description 6
- 238000005261 decarburization Methods 0.000 description 5
- 230000009471 action Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 239000002156 adsorbate Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004108 freeze drying Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000012432 intermediate storage Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009919 sequestration Effects 0.000 description 1
- 238000001926 trapping method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Abstract
The invention relates to a flue gas carbon dioxide recovery method and a system, wherein the method comprises the following steps: sending the flue gas into a temperature swing adsorption tower for temperature swing adsorption treatment to obtain first decarbonized gas; regenerating the first adsorbent filled in the temperature swing adsorption tower to obtain first-stage concentrated gas; and introducing the first-stage concentrated gas into a pressure swing adsorption tower for pressure swing adsorption separation, and then desorbing a second adsorbent in the pressure swing adsorption tower to obtain second decarbonized gas and second-stage concentrated gas. According to the flue gas carbon dioxide recovery method provided by the invention, through adopting a temperature-swing pressure-swing adsorption secondary coupling process, the flue gas can realize the carbon dioxide trapping rate of not less than 90% after temperature-swing adsorption and pressure-swing adsorption in sequence, and the flue gas is subjected to temperature-swing adsorption first, and the adsorbent in the temperature-swing adsorption tower is regenerated by utilizing heat energy, so that the regeneration efficiency of the adsorbent in the temperature-swing adsorption tower and the adsorption capacity during working can be obviously improved, and the flue gas treatment capacity is improved.
Description
Technical Field
The invention belongs to the field of environmental protection, and particularly relates to a method and a system for recycling carbon dioxide in flue gas.
Background
In recent years, carbon dioxide is discharged into the air in a large amount due to the reasons of industrial production, transportation and the like, so that the content of atmospheric carbon dioxide is continuously increased, the greenhouse effect is increased, and serious harm is caused to the natural environment.
CO 2 The capture and utilization and sequestration technology (CCUS) aims to capture and purify carbon dioxide generated during production and then put it into a new production process or sequestered in the ocean or groundwater layers to solve the greenhouse effect problem. In CO 2 In the trapping process, aiming at the emission of high-flow low-concentration carbon dioxide gas of coal-fired power plants and gas units, the current mature method is a solvent absorption method, however, the solvent absorption method has the problems of high energy consumption, short service life, difficult solvent regeneration and the like, and other carbon dioxide trapping methods such as a physical adsorption method and a membrane separation method have low technical maturity and lack large-scale technical verification experiments. The physical adsorption method has the advantages of low theoretical energy consumption, simple equipment structure, simple and convenient operation and control, and the adsorption material is generally nontoxic and harmless and has long service life, thus having great potential in the carbon dioxide trapping technology.
Physical adsorption methods can be classified into pressure swing adsorption and temperature swing adsorption according to the regeneration mode of the adsorbent. Pressure swing adsorption enables the adsorbent to generate adsorption-desorption-adsorption circulation process in the adsorption tower by changing the pressure of each step, thereby realizing effective separation of carbon dioxide and having wider industrial application. The temperature swing adsorption process is to change the temperature of each step to make the adsorbate generate adsorption-desorption-adsorption circulation process in the adsorption tower, for example, CN114405227A provides a temperature swing adsorption method for capturing flue gas and carbon dioxide for a power plant.
However, the adsorbents with extremely high adsorption capacity such as zeolite molecular sieve, active carbon and the like have extremely limited desorption capacity in the pressure swing process, the carbon dioxide separation rate is low, the desorption rate is low, and the flue gas trapping cost with low carbon dioxide content is too high; in the temperature swing adsorption process, the temperature of the adsorbent is very slow to rise and fall, and the adsorption time sequence cannot be effectively matched.
Disclosure of Invention
The invention aims to provide a flue gas carbon dioxide recovery method and a flue gas carbon dioxide recovery system, and the method has the advantages of low energy consumption and high carbon dioxide capture rate.
In order to achieve the above object, the present invention provides a flue gas carbon dioxide recovery method, comprising the steps of:
sending the flue gas into a temperature swing adsorption tower for temperature swing adsorption treatment to obtain first decarbonized gas;
regenerating the first adsorbent filled in the temperature swing adsorption tower to obtain first-stage concentrated gas;
and introducing the first-stage concentrated gas into a pressure swing adsorption tower for pressure swing adsorption separation, and then desorbing a second adsorbent in the pressure swing adsorption tower to obtain second decarbonized gas and second-stage concentrated gas.
Optionally, the temperature swing adsorption treatment conditions include: the adsorption temperature is 40-60 ℃, and the adsorption pressure is 0.03-0.06MPaG; the conditions of the pressure swing adsorption treatment include: the adsorption temperature is 40-60 ℃, and the adsorption pressure is 0.03-0.06MPaG; preferably, the first adsorbent is selected from one or more of a high silicon molecular sieve and activated carbon, preferably activated carbon; the second adsorbent is selected from one or more of activated carbon and silica gel, preferably activated carbon.
Optionally, the regeneration process includes the steps of: introducing heated high-concentration circulating gas into the temperature swing adsorption tower, heating the temperature swing adsorption tower to a regeneration temperature, and desorbing the first adsorbent to obtain a mixed gas of the first-stage concentrated gas and the cooled high-concentration circulating gas; then, introducing the first decarbonizing gas or the low-concentration circulating gas into the temperature swing adsorption tower, and cooling the temperature swing adsorption tower to the pressure swing adsorption temperature to obtain the first decarbonizing gas after temperature rise; wherein the volume fraction of carbon dioxide in the high-concentration circulating gas is 70-95vol%; the volume fraction of carbon dioxide in the first decarbonizing gas is 0-0.75vol%; the volume fraction of carbon dioxide in the low-concentration circulating gas is 1-5vol%.
Optionally, the method further comprises: heating one of the mixed gases to a first temperature and returning the mixed gas to the temperature swing adsorption tower for regenerating the first adsorbent; and/or cooling the warmed first decarbonized gas or the low-concentration circulating gas to a second temperature and returning the cooled first decarbonized gas or the low-concentration circulating gas to the temperature-swing adsorption tower, so that the temperature-swing adsorption tower is cooled to the adsorption temperature after being regenerated; the first temperature is 200-250 ℃; the second temperature is 20-30 ℃.
Optionally, the regeneration temperature is 80-120 ℃; the vacuum degree of desorption treatment of the first adsorbent is 40-50kPa; the vacuum degree of the desorption treatment of the second adsorbent is 60-70kPa; preferably, the volume fraction of carbon dioxide in the second decarbonizing gas is 10-15vol%; the volume fraction of carbon dioxide in the secondary concentrated gas is 90-95vol%.
Optionally, the method further comprises: pressurizing the flue gas to 0.03-0.06MPaG before the flue gas is sent to the temperature swing adsorption tower; and returning the second decarbonized gas to the temperature swing adsorption column; the flue gas is at least one selected from the group consisting of power plant flue gas, cement plant flue gas, steel plant flue gas, metallurgical plant flue gas and chemical plant flue gas; the volume fraction of carbon dioxide in the flue gas is 5-15vol%.
A second aspect of the invention provides a flue gas carbon dioxide recovery system,
the system comprises a temperature swing adsorption tower, a pressure swing adsorption tower, a first storage tank and a second storage tank; the second storage tank is communicated with the pressure swing adsorption device;
the top of the temperature swing adsorption tower is switchably communicated with the first storage tank and the second storage tank; a first heat exchanger is arranged on a pipeline between the second storage tank and the top of the temperature swing adsorption tower;
the bottom of the temperature swing adsorption tower is switchably communicated with the first storage tank, the flue gas supply pipeline and the second storage tank.
Optionally, a second heat exchanger is arranged on a pipeline between the first storage tank and the bottom of the temperature swing adsorption tower; and/or the top of the pressure swing adsorption tower is connected back to the flue gas supply pipeline through a circulating pipeline.
Optionally, a first fan is arranged on a pipeline between the first storage tank and the second heat exchanger; and/or a second fan is arranged on a pipeline between the second storage tank and the first heat exchanger.
Optionally, a first vacuum pump is arranged on a pipeline between the temperature swing adsorption tower and the second storage tank; and/or a third fan is arranged on a pipeline between the second storage tank and the pressure swing adsorption tower.
According to the technical scheme, the flue gas carbon dioxide recovery method provided by the invention adopts the temperature-swing adsorption secondary coupling process, so that the carbon dioxide capture rate of not less than 90% can be realized after the flue gas is subjected to temperature-swing adsorption and pressure-swing adsorption in sequence, the flue gas is subjected to temperature-swing adsorption first, the adsorbent in the temperature-swing adsorption tower is regenerated by using heat energy, the regeneration efficiency of the adsorbent in the temperature-swing adsorption tower and the adsorption capacity during working can be obviously improved, and the flue gas treatment capacity is improved.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention. In the drawings:
FIG. 1 is a schematic diagram of a flue gas carbon dioxide recovery process according to one embodiment of the present invention.
Reference numerals illustrate:
101. pipeline 102, fourth fan 103, pipeline 104, and temperature swing adsorption tower
105. Line 106, first tank 107, line 108, line
109. First vacuum pump 110, line 111, second storage tank 201, and line
202. Third fan 203, pipeline 204, pressure swing adsorption tower 205, pipeline
206. A second vacuum pump 207, a pipeline 301, a pipeline 302, and a first fan
303. Pipeline 304, first heat exchanger 305, pipeline 306, second fan
307. Line 308, second heat exchanger 309, line
Detailed Description
The following describes specific embodiments of the present invention in detail. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
The invention provides a flue gas carbon dioxide recovery method, which comprises the following steps:
sending the flue gas into a temperature swing adsorption tower for temperature swing adsorption treatment to obtain first decarbonized gas;
regenerating the first adsorbent filled in the temperature swing adsorption tower to obtain first-stage concentrated gas;
and introducing the first-stage concentrated gas into a pressure swing adsorption tower for pressure swing adsorption separation, and then desorbing a second adsorbent in the pressure swing adsorption tower to obtain second decarbonized gas and second-stage concentrated gas.
According to the technical scheme, the flue gas carbon dioxide recovery method provided by the invention adopts the temperature-swing adsorption secondary coupling process, so that the carbon dioxide capture rate of not less than 90% can be realized after the flue gas is subjected to temperature-swing adsorption and pressure-swing adsorption in sequence, the flue gas is subjected to temperature-swing adsorption first, the first adsorbent is regenerated by using heat energy, the regeneration efficiency of the first adsorbent and the adsorption capacity during working are obviously improved, and the flue gas treatment capacity can be improved by matching with the time sequence of the pressure-swing adsorption.
The temperature swing adsorption is an operation method for adsorbing and desorbing adsorbed substances by adopting temperature near the ambient temperature, and the adsorbent is regenerated by utilizing heat energy, so that the regeneration efficiency of the adsorbent is improved. Specifically, the conditions of the temperature swing adsorption treatment include: the adsorption temperature is 40-60 ℃, and the adsorption pressure is 0.03-0.06MPaG.
In the invention, the pressure swing adsorption treatment is carried out under a lower pressure, so that the energy consumption required by compressed gas can be saved, and the conditions of the pressure swing adsorption treatment comprise: the adsorption temperature is 40-60 ℃, and the adsorption pressure is 0.03-0.06MPaG.
Wherein the first adsorbent is selected from one or more of high-silicon molecular sieve and active carbon; the adsorbent has extremely high adsorption capacity, however, the desorption capacity of the adsorbent in the pressure swing adsorption process is limited, so that the adsorbent can be used for temperature swing adsorption to better remove carbon dioxide in low-concentration flue gas. In some embodiments of the present invention, the first adsorbent and the second adsorbent are spherical or spheroid-like particles having a particle size of 0.5 to 3mm in order to increase the adsorption treatment efficiency. Preferably, the first adsorbent is activated carbon.
In the present invention, the adsorbent bed of the temperature swing adsorption column is also packed with an adsorbent having a high adsorption amount, and specifically, the second adsorbent is selected from one or more of activated carbon and silica gel. Preferably, the second adsorbent is activated carbon.
The temperature swing adsorption tower and the adsorbents filled in the pressure swing adsorption tower have higher adsorption capacity, wherein in the temperature swing adsorption process, by changing the temperature of each step, the temperature swing adsorbent generates adsorption-desorption-adsorption circulation process in the temperature swing adsorption tower, and has better treatment effect when being used for adsorbing the flue gas with lower carbon dioxide concentration. In the pressure swing adsorption tower, the pressure of each step in the adsorption tower is changed, so that the adsorption-desorption-adsorption circulation process occurs in the pressure swing adsorption tower, the treatment process time of each step is short, the flow is simple, and the pressure swing adsorption tower can adapt to various working conditions.
Wherein the regeneration process comprises the steps of: introducing heated high-concentration circulating gas into the temperature swing adsorption tower, heating the temperature swing adsorption tower to a regeneration temperature, and desorbing the first adsorbent to obtain a mixed gas of the first-stage concentrated gas and the cooled high-concentration circulating gas; and then introducing the first decarbonizing gas or the low-concentration circulating gas into the temperature swing adsorption tower, and cooling the temperature swing adsorption tower to the pressure swing adsorption temperature to obtain the warmed first decarbonizing gas. Because the temperature rise and the temperature drop of the adsorbent are very slow in the traditional temperature swing adsorption process, the method is more suitable for treating the flue gas with low carbon dioxide concentration. The invention can realize the rapid temperature rise and fall of the temperature swing adsorption tower by adopting the circulating gas thermal regeneration process, the regeneration efficiency of the first adsorbent is high, and the regeneration time is matched with the adsorption time.
In the invention, the gas used for cooling the first adsorbent can be first decarbonizing gas or low-concentration circulating gas, when the gas is the first decarbonizing gas, the first decarbonizing gas processed by the temperature swing adsorption tower is sent into the intermediate storage tank for storage, and when the first adsorbent is processed by the high-temperature high-concentration circulating gas, the first decarbonizing gas is then introduced into the temperature swing adsorption tower. When the gas is low-concentration circulating gas, the flue gas is exhausted after being treated by the temperature-swing adsorption tower, and the low-concentration circulating gas is introduced into the temperature-swing adsorption tower after the first adsorbent is treated by the high-temperature high-concentration circulating gas. Specifically, the low-concentration circulating gas is a circulating gas which is lower in temperature and contains lower carbon dioxide concentration, and the volume fraction of carbon dioxide in the low-concentration circulating gas is 1-5vol%.
Wherein the high-concentration circulating gas is a circulating gas with higher temperature and higher carbon dioxide concentration, specifically, the volume fraction of carbon dioxide in the high-concentration circulating gas is 70-95vol%, and the temperature of the high-concentration circulating gas is 200-250 ℃; the volume fraction of carbon dioxide in the first decarbonizing gas is 0-0.75vol% and the temperature of the first decarbonizing gas is 20-30 ℃. In some embodiments of the invention, the high concentration recycle gas may be a first stage concentrate gas.
Wherein the method further comprises: and heating one of the mixed gases to a first temperature, and returning the mixed gas to the temperature swing adsorption tower for regenerating the first adsorbent, wherein the first temperature is 200-300 ℃, and can be 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃ and 300 ℃ or any value in the range. It should be noted that the "one-shot" refers to a part of the mixed gas, the specific flow rate can be adjusted according to the flow rate of the high carbon dioxide concentration required for regenerating the temperature swing adsorbent, and the remaining mixed gas with high carbon dioxide concentration is introduced into the pressure swing adsorption tower for further separation.
In the invention, the method further comprises the steps of cooling the warmed first decarburization gas or the low-concentration circulating gas to a second temperature and returning the cooled first decarburization gas or the low-concentration circulating gas to the temperature swing adsorption tower, so that the temperature swing adsorption tower is cooled to the adsorption temperature after being regenerated; specifically, the second temperature is 20 to 30 ℃, and may be, for example, 20 ℃, 21 ℃, 22 ℃, 23 ℃, 24 ℃, 25 ℃, 26 ℃, 27 ℃, 28 ℃, 29 ℃, 30 ℃, or any value within the foregoing range.
Wherein, in the temperature-changing adsorbent regeneration process, the regeneration temperature is 80-120 ℃; and carrying out desorption treatment on the first adsorbent, wherein the vacuum degree is 40-50kPa.
Wherein the vacuum degree of the desorption treatment of the second adsorbent is 60-70kPa, and a vacuum device can be specifically adopted to pump out carbon dioxide product gas. After the primary concentrated gas is subjected to pressure swing adsorption treatment, the volume fraction of carbon dioxide in the second decarbonizing gas is 10-15vol%; the volume fraction of carbon dioxide in the secondary concentrated gas is 90-95vol%.
Wherein the method further comprises: pressurizing the flue gas to 0.03-0.06MPaG before the flue gas is sent to the temperature swing adsorption tower; the compression of the flue gas to the pressure is beneficial to improving the driving force of the flue gas for temperature swing adsorption.
After the primary concentrated gas is subjected to pressure swing adsorption separation treatment, the concentration of carbon dioxide in the second decarbonizing gas is about 15vol%, and the second decarbonizing gas can be returned to the temperature swing adsorption tower or mixed with flue gas and then introduced into the temperature swing adsorption tower.
Specifically, the flue gas is at least one selected from the group consisting of power plant flue gas, cement plant flue gas, steel plant flue gas, metallurgical plant flue gas and chemical plant flue gas; the volume fraction of carbon dioxide in the flue gas is 5-15vol%.
A second aspect of the present invention provides a flue gas carbon dioxide recovery system comprising a temperature swing adsorption column, a pressure swing adsorption column, a first storage tank, and a second storage tank; the second storage tank is communicated with the pressure swing adsorption device; the top of the temperature swing adsorption tower is switchably communicated with the first storage tank and the second storage tank; a first heat exchanger is arranged on a pipeline between the second storage tank and the top of the temperature swing adsorption tower; the bottom of the temperature swing adsorption tower is switchably communicated with the first storage tank, the flue gas supply pipeline and the second storage tank.
The second storage tank may be used to store the high-concentration recycle gas, or may be used to store the first-stage concentrate gas. The first storage tank may be used to store a first level of decarbonizing gas or a low concentration recycle gas. When the first storage tank is used for storing the first-stage decarbonization gas, a part of the stored first-stage decarbonization gas is used for returning to the temperature-swing adsorption tower so as to cool the desorbed adsorption bed to the adsorption temperature, and the other part of the stored first-stage decarbonization gas is emptied or sent to the tail gas treatment system.
Wherein a second heat exchanger is arranged on a pipeline between the first storage tank and the bottom of the temperature swing adsorption tower; and/or the top of the pressure swing adsorption tower is connected back to the flue gas supply pipeline through a circulating pipeline.
Wherein a first fan is arranged on a pipeline between the first storage tank and the second heat exchanger; and/or a second fan is arranged on a pipeline between the second storage tank and the first heat exchanger.
Wherein a first vacuum pump is arranged on a pipeline between the temperature swing adsorption tower and the second storage tank; and/or a third fan is arranged on a pipeline between the second storage tank and the pressure swing adsorption tower.
Specifically, the flue gas supply pipeline is also provided with a fourth fan for pressurizing the flue gas.
The first fan, the second fan, the third fan and the fourth fan are used for pressurizing gas, and can be a blower or a compressor.
The first heat exchanger is used for heating the high-concentration circulating gas, wherein the heat medium can be water vapor, preferably, the temperature of the water vapor is not lower than 300 ℃, and the temperature of the high-concentration circulating gas at the outlet of the first heat exchanger is not lower than 200 ℃.
The second heat exchanger is used for cooling the first decarburization gas, wherein the cooling medium is cooling water, preferably, the temperature of the cooling water is 15-25 ℃, and the temperature of the first decarburization gas at the outlet of the second heat exchanger is not higher than 30 ℃.
And a flowmeter, a temperature transmitter, a pressure transmitter, an electric switch valve and the like are further arranged on a pipeline of the system and used for controlling or adjusting flow, pressure and temperature.
In some preferred embodiments, the system further comprises a control module for centralized control of the devices within the system to achieve low energy consumption and efficient capture of carbon dioxide.
Referring to the flow chart shown in fig. 1, the flue gas from the flue gas supply pipeline 101 is pressurized to 0.03-0.06mpa g by the fourth fan 102, the temperature of the flue gas is raised to 40-60 ℃, then the compressed flue gas is introduced into the temperature swing adsorption tower 104 through the pipeline 103, the number of temperature swing adsorption towers is more, preferably 3-4, the first decarbonization gas which is not adsorbed by the temperature swing adsorption towers is introduced into the first storage tank 106 through the pipeline 105, and the first decarbonization gas stored in the decarbonization gas buffer tank 106 can be used for cooling the adsorption bed layer of the temperature swing adsorption tower or evacuating through the pipeline 107.
The operation process of the temperature swing adsorption tower comprises adsorption and first adsorbent regeneration, during the first adsorbent regeneration treatment process, the high-carbon dioxide concentration circulating gas in the second storage tank 111 is pumped into the first heat exchanger 304 by the first fan 302 to be heated to a first temperature, then the heated high-concentration circulating gas is introduced from the top of the temperature swing adsorption tower 104 to perform temperature rising desorption on the first adsorbent in the adsorbent bed, and after the adsorbent bed is raised to a set temperature, the first-stage concentrated gas obtained by the high-concentration circulating gas and desorption is pumped into the second storage tank 111 by the first vacuum pump 109; then the second fan 306 is utilized to cool the first decarbonizing gas in the first storage tank 106 to a second temperature through the second heat exchanger 308, the cooled first decarbonizing gas or low-concentration circulating gas is introduced into the temperature swing adsorption tower to cool the first adsorbent, and when the adsorbent bed is cooled to a set temperature, the regeneration process of the first adsorbent is finished.
The first-stage concentrated gas desorbed from the first adsorbent in the temperature swing adsorption tower enters the second storage tank 111 under the suction action of the first vacuum pump 109, is pressurized to 0.03-0.06MPaG by the third fan 202, the temperature of the first-stage concentrated gas is increased to 40-60 ℃, the compressed first-stage concentrated gas is sent into the pressure swing adsorption tower 204, and then carbon dioxide product gas is obtained under the suction action of the second vacuum pump 206. The second decarbonized gas obtained by pressure swing adsorption separation is mixed with the flue gas in the flue gas supply pipeline 101 through a pipeline 208 and then returned to the temperature swing adsorption tower.
As shown in fig. 1, the top of the temperature swing adsorption tower 104 is switchably communicated with the second storage tank 111 and the first storage tank 106, and the bottom of the temperature swing adsorption tower is switchably communicated with the first storage tank 106, the pipeline 103 and the second storage tank 111, and specifically, whether the pipeline is communicated or not can be controlled by a programmable valve.
When the temperature swing adsorption tower adsorbs the flue gas, the bottom of the temperature swing adsorption tower is communicated with the pipeline 103 (or the flue gas supply pipeline) (can be controlled to be opened and closed by a programmable valve), and the pipeline between the temperature swing adsorption tower and the first storage tank 106 and the second storage tank 111 is controlled to be in a closed state by the programmable valve, and the programmable valve on the pipeline 105 is opened. After the adsorption is completed, the program control valves on the pipeline 103 and the pipeline 105 are closed, the program control valve on the pipeline 305 is opened, the first fan is started, the high-concentration circulating gas in the second storage tank 111 is heated up through the first heat exchanger 304, the adsorbent bed is heated up from the top of the temperature swing adsorption tower 104, after the adsorbent bed is heated up to a certain temperature, the program control valve on the pipeline 108 is opened, the first vacuum pump 109 is opened, the high-concentration circulating gas and the first-stage concentrated gas enter the second storage tank 111, part of the gas in the second storage tank 111 is sent to the pressure swing adsorption tower 204 for further treatment, and the part of the gas is stored in the second storage tank 111 as circulating gas.
Then closing the program-controlled valves on the pipeline 305 and the pipeline 108, opening the program-controlled valves on the pipeline 105 and the pipeline 309, cooling the first decarbonizing gas or the low-concentration circulating gas stored in the first storage tank 106 through the second heat exchanger 308, introducing the cooled first decarbonizing gas or the low-concentration circulating gas into the temperature-variable adsorption tower 104, cooling the adsorption bed, and returning the cooled first decarbonizing gas or the low-concentration circulating gas to the first storage tank 106 through the pipeline 105.
The present invention will be further illustrated in detail by the following examples, but the present invention is not limited to the following examples.
Example 1
Taking low-concentration desulfurized power plant flue gas as an example, the low-concentration CO in the power plant flue gas is recycled by adopting the flue gas carbon dioxide recycling system shown in the figure 1 2 Collecting and recovering, and evaluating the system for CO 2 Is a processing effect of (a).
446kmol/h, 0.5kPaG, CO at 55deg.C 2 The flue gas of the power plant with the content of 14.2 percent vol and low concentration after desulfurization enters a raw material buffer tank, is pressurized to 0.04MPaG by a third fan 102, the temperature of the flue gas is increased to 60 ℃, then the compressed flue gas 103 is introduced into a temperature swing adsorption tower 104, the temperature swing adsorption tower comprises 3 temperature swing adsorption towers, and a first decarburization gas which is not adsorbed by the temperature swing adsorption device is introduced into a first storage tank 106 through a line 105 and is emptied through a line 107, wherein the first adsorbent is filled in an adsorption bed of the temperature swing adsorption tower 104.
The operation process of the temperature swing adsorption tower comprises adsorption and first adsorbent regeneration, during the first adsorbent regeneration treatment process, the high-carbon dioxide concentration circulating gas in the second storage tank 111 is pumped into the first heat exchanger 304 by the first fan 302 to be heated to a first temperature, then the heated high-concentration circulating gas is introduced from the top of the temperature swing adsorption tower 104 to perform temperature rising desorption on the first adsorbent in the adsorbent bed, and after the adsorbent bed is raised to a set temperature, the first-stage concentrated gas obtained by the high-concentration circulating gas and desorption is pumped into the second storage tank 111 by the first vacuum pump 109; then the second fan 306 is utilized to cool the low-concentration circulating gas in the first storage tank 106 to a second temperature through the second heat exchanger 308, the cooled first decarbonizing gas is introduced into the temperature swing adsorption tower to cool the first adsorbent, and when the adsorbent bed is cooled to a set temperature, the regeneration process of the first adsorbent is finished.
The first-stage concentrated gas desorbed from the first adsorbent in the temperature swing adsorption tower enters the second storage tank 111 under the suction action of the first vacuum pump 109, is then pressurized to 0.04MPaG by the third fan 202, the temperature of the first-stage concentrated gas is increased to 45 ℃, and then the compressed first-stage concentrated gas is sent into the pressure swing adsorption tower 204, and then carbon dioxide product gas is obtained under the suction action of the second vacuum pump 206. The second decarbonized gas 208 obtained by pressure swing adsorption separation is mixed with the flue gas 101 and then returned to the temperature swing adsorption tower.
Wherein, the first adsorbent filled in the temperature swing adsorption tower is activated carbon, and the second adsorbent filled in the pressure swing adsorption tower is activated carbon.
CO 2 The energy consumption for trapping and recycling is 1.72GJ/tCO 2 。
TABLE 1
As can be seen from Table 1, the flow rate was 446kmol/h and CO was measured by the method of the present invention 2 The flue gas of the power plant with the content of 14.2vol percent is treated, and after the temperature swing adsorption separation treatment, the flow rate of the first decarbonizing gas is 248.4kmol/h and CO 2 The content is reduced to 0.4vol percent, and the CO in the first-stage concentrated gas 2 The content was 42.2vol%; after the pressure swing adsorption separation treatment of the first-stage concentrated gas, CO in the carbon dioxide product gas 2 The content was 94.5vol%; CO in the second decarbonizing gas 2 The content was 11.8vol%.
Example 2
The embodiment aims at CO in the flue gas of the power plant 2 The method for collecting and recovering is different from example 1 in that: flue gas channelThe fourth fan is boosted to 50kPaG, and the first-stage concentrated gas is boosted to 50kPaG through the third fan; the temperature of the adsorbent bed during the temperature swing adsorption process was 60 ℃.
CO 2 The trapping energy consumption is 1.80GJ/tCO 2 。
Example 3
The embodiment aims at CO in the flue gas of the power plant 2 The method for collecting and recovering is different from example 1 in that:
the temperature of the high-concentration circulating gas is 250 ℃; the temperature of the low concentration recycle gas was 30 ℃.
CO 2 The trapping energy consumption is 1.82GJ/tCO 2 。
From the above examples, the invention provides a method for extracting CO from flue gas 2 The method for collecting and recovering CO in the flue gas can meet the requirement of 2 The trapping requirement is high, the trapping rate is high, the regeneration energy consumption of the adsorbent can be reduced, the temperature swing adsorption and the pressure swing adsorption are matched, and the adsorption treatment time is shortened.
Comparative example 1
CO in the flue gas of the Power plant of this comparative example 2 The method of trapping is described with reference to example 1, with the difference that: the flue gas is boosted to 20kPaG by a fourth fan, a temperature swing adsorption tower is filled with molecular sieve adsorbents, the first-stage concentrated gas is boosted to 50kPaG by a third fan, a pressure swing adsorption tower is filled with silica gel adsorbents, a freeze drying dehydration and pressure swing adsorption dehydration unit is needed to be added before the temperature swing adsorption tower, and electricity consumption and low-carbon steam are needed to be consumed for dehydration and purification.
CO 2 The trapping energy consumption is 1.92GJ/tCO 2 The energy consumption is higher.
Comparative example 2
CO in the flue gas of the Power plant of this comparative example 2 The method of trapping is described with reference to example 1, with the difference that: the high-concentration circulating gas is first-stage concentrated gas, wherein the concentration of carbon dioxide is 45vol% and the temperature is 180 ℃; the carbon dioxide concentration in the low concentration recycle gas was 13vol% and the temperature was 18 ℃.
CO 2 The trapping energy consumption is 1.96GJ/tCO 2 The energy consumption is higher.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction. The various possible combinations of the invention are not described in detail in order to avoid unnecessary repetition.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.
Claims (10)
1. A flue gas carbon dioxide recovery method, characterized in that the method comprises the following steps:
sending the flue gas into a temperature swing adsorption tower for temperature swing adsorption treatment to obtain first decarbonized gas;
regenerating the first adsorbent filled in the temperature swing adsorption tower to obtain first-stage concentrated gas;
and introducing the first-stage concentrated gas into a pressure swing adsorption tower for pressure swing adsorption separation, and then desorbing a second adsorbent in the pressure swing adsorption tower to obtain second decarbonized gas and second-stage concentrated gas.
2. The method of claim 1, wherein the temperature swing adsorption process conditions comprise: the adsorption temperature is 40-60 ℃, and the adsorption pressure is 0.03-0.06MPaG;
the conditions of the pressure swing adsorption treatment include: the adsorption temperature is 40-60 ℃, and the adsorption pressure is 0.03-0.06MPaG;
preferably, the first adsorbent is selected from one or more of a high silicon molecular sieve and activated carbon, preferably activated carbon;
the second adsorbent is selected from one or more of activated carbon and silica gel, preferably activated carbon.
3. The method of claim 1, wherein the regeneration process comprises the steps of:
introducing heated high-concentration circulating gas into the temperature swing adsorption tower, heating the temperature swing adsorption tower to a regeneration temperature, and desorbing the first adsorbent to obtain a mixed gas of the first-stage concentrated gas and the cooled high-concentration circulating gas;
then, introducing the first decarbonizing gas or the low-concentration circulating gas into the temperature swing adsorption tower, and cooling the temperature swing adsorption tower to the pressure swing adsorption temperature to obtain the first decarbonizing gas after temperature rise;
wherein the volume fraction of carbon dioxide in the high-concentration circulating gas is 70-95vol%; the volume fraction of carbon dioxide in the first decarbonizing gas is 0-0.75vol%; the volume fraction of carbon dioxide in the low-concentration circulating gas is 1-5vol%.
4. A method according to claim 3, wherein the method further comprises: heating one of the mixed gases to a first temperature and returning the mixed gas to the temperature swing adsorption tower for regenerating the first adsorbent; and/or
Cooling the warmed first decarbonized gas or the low-concentration circulating gas to a second temperature and returning to the temperature-swing adsorption tower, so that the temperature-swing adsorption tower is cooled to the adsorption temperature after being regenerated;
the first temperature is 200-250 ℃; the second temperature is 20-30 ℃.
5. A method according to claim 3, wherein the regeneration temperature is 80-120 ℃;
the vacuum degree of desorption treatment of the first adsorbent is 40-50kPa;
the vacuum degree of the desorption treatment of the second adsorbent is 60-70kPa;
preferably, the volume fraction of carbon dioxide in the second decarbonizing gas is 10-15vol%;
the volume fraction of carbon dioxide in the secondary concentrated gas is 90-95vol%.
6. The method of claim 1, wherein the method further comprises: pressurizing the flue gas to 0.03-0.06MPaG before the flue gas is sent to the temperature swing adsorption tower; and
returning the second decarbonized gas to the temperature swing adsorption tower;
the flue gas is at least one selected from the group consisting of power plant flue gas, cement plant flue gas, steel plant flue gas, metallurgical plant flue gas and chemical plant flue gas;
the volume fraction of carbon dioxide in the flue gas is 5-15vol%.
7. The flue gas carbon dioxide recovery system is characterized by comprising a temperature swing adsorption tower, a pressure swing adsorption tower, a first storage tank and a second storage tank; the second storage tank is communicated with the pressure swing adsorption device;
the top of the temperature swing adsorption tower is switchably communicated with the first storage tank and the second storage tank; a first heat exchanger is arranged on a pipeline between the second storage tank and the top of the temperature swing adsorption tower;
the bottom of the temperature swing adsorption tower is switchably communicated with the first storage tank, the flue gas supply pipeline and the second storage tank.
8. The system of claim 7, wherein a second heat exchanger is disposed on a conduit between the first storage tank and the bottom of the temperature swing adsorption column; and/or
The top of the pressure swing adsorption tower is connected back to the flue gas supply pipeline through a circulating pipeline.
9. The system of claim 8, wherein a first fan is disposed on the conduit between the first storage tank and the second heat exchanger; and/or
And a second fan is arranged on a pipeline between the second storage tank and the first heat exchanger.
10. The system of claim 7, wherein a first vacuum pump is disposed on a conduit between the temperature swing adsorption tower and the second storage tank; and/or
And a third fan is arranged on a pipeline between the second storage tank and the pressure swing adsorption tower.
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