CN113648826A

CN113648826A - Synergistic CO removal based on calcium circulation2And NO process

Info

Publication number: CN113648826A
Application number: CN202110961765.1A
Authority: CN
Inventors: 李英杰; 张婉; 张春晓; 赵建立
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2021-08-20
Filing date: 2021-08-20
Publication date: 2021-11-16
Anticipated expiration: 2041-08-20
Also published as: CN113648826B

Abstract

The invention relates to the technical field of environmental pollutant prevention and control and clean combustion, in particular to a synergistic CO removal method based on calcium circulation₂And NO, said method being: (1) calcining the Mn modified CaO catalyst by coal or biomass, and generating unburned coal coke or biomass coke; (2) the coal coke or the biomass coke reacts with oxygen in the flue gas to generate CO and CO₂Coke quilt O₂And NO_xExhaustion; the NO is reduced into N by CO under the catalysis of the Mn modified CaO catalyst₂(ii) a CO in the furnace₂Is absorbed by Mn-CaO; oxidizing residual CO in the flue gas into CO by air₂，CO₂Is absorbed by Mn-CaO. CO generated by oxidizing coal coke or biomass coke is used as a reducing agent, and a denitration reducing agent and a denitration reactor are not required to be additionally added, so that the existing calcium circulation system is usedThe calcium-based absorbent is subjected to Mn modification treatment, and CO in the flue gas of the coal-fired power plant is realized in a carbonation reactor with calcium circulation₂High-efficiency removal of NO and denitration efficiency up to 99 percent, and CO₂The trapping efficiency is as high as 88%.

Description

Synergistic CO removal based on calcium circulation2And NO process

Technical Field

The invention relates to a ringThe technical field of environmental pollutant prevention and control and clean combustion, in particular to a synergistic CO removal method based on calcium circulation₂And NO.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Coal-fired power plant is fossil energy-related CO₂Main source of emission, CO for coal-fired power plant₂Emission reduction is an important part of the global carbon emission reduction work. The calcium cycling technique, CaO cycling calcination/carbonation, is currently the most promising technique for large scale CO production₂One of the trapping technologies has the advantages of high trapping efficiency, low cost, good coupling with a power plant and the like. The calcium cycle includes two reactors, a carbonation reactor and a calciner reactor, all being fluidized bed reactors. CaCO₃Calcining in a calcining furnace at 800-950 ℃ to decompose and generate CO₂And CaO (shown in formula (1)), the calciner is powered by fuel combustion; the calcined CaO flows into a carbonation furnace at the temperature of 600-700 ℃ to absorb CO in the flue gas₂Formation of CaCO₃(as shown in formula (2)); last CaCO₃Returning to the calcining furnace to carry out decomposition reaction and release CO₂And realizes the regeneration of CaO. CaO circularly flows in the calcining furnace and the carbonating furnace to realize CO₂And (4) trapping. High concentration CO discharged from calciner₂Can be directly sealed or utilized.

CaCO₃→CaO+CO₂ (1)

CaO+CO₂→CaCO₃ (2)

CaCO in calciner₃Decomposition is an endothermic reaction, and the calciner is typically powered by oxygen-rich combustion of coal or biomass. When the calcined CaO flows out of the calciner, some of the unburned coke or biomass coke in the calciner is entrained by the CaO and flows into the carbonator where it is entrained with the O in the flue gas₂The reaction takes place to form CO. By coke type, entrainment and flue gasO₂The concentration influences the CO concentration in the carbonator to be about 0.1-1.2%. The CO has reducibility, but the CO in the carbonator is not reasonably utilized currently, the emission of the CO causes energy waste and pollution to the environment, and the part of the CO needs to be recycled. Meanwhile, the calcium-based absorbent in the calcium circulation can trap CO along with the increase of the circulation times₂The performance gradually declines, and a composite calcium-based absorbent with high activity is necessary to be prepared.

As one of the main pollutants of coal-fired power plants, NO is a great hazard to the environment, such as acid rain, photochemical smog, and the like. Currently, NO removal from coal-fired power plants relies primarily on NH₃The SCR technology is realized, and although the denitration efficiency of the technology can reach more than 90%, the catalyst such as vanadium-titanium and the like has high cost, is easy to be poisoned and inactivated and is difficult to recover; and NH₃High toxicity, difficult transportation and storage and strong corrosion to equipment. If CO is adopted as a reducing agent for denitration, NH can be avoided₃Corrosion to equipment and difficulty in transportation, and the like, and simultaneously CO has the advantages of low price, wide source and the like, but CO is easy to be oxidized₂Oxidation, so that CO cannot realize efficient denitration under aerobic condition, which is the biggest problem faced by CO-SCR; the coal-fired power plant is low in cost, high in efficiency and safe in denitration and needs to be solved urgently.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a synergistic CO removal method based on calcium circulation₂And the method for preparing NO utilizes CO generated by coke oxidation in the calcium cycle carbonation process as a denitration reducing agent, takes Mn modified CaO as a denitration catalyst and CO₂Absorbent for CO production during calcium cycle carbonation₂High efficiency and NO removal, denitration efficiency up to 99%, CO₂The trapping efficiency is as high as 88%.

In order to achieve the above object, the technical solution of the present invention is as follows:

in a first aspect of the invention, a synergistic CO removal based on calcium cycling is provided₂And NO, said method being:

(1) calcining the Mn modified CaO catalyst by coal or biomass, and generating unburned coal coke or biomass coke;

(2) the coal coke or the biomass coke reacts with oxygen in the flue gas to generate CO and CO₂Coke quilt O₂And NO_xExhaustion; the NO is reduced into N by CO under the catalysis of the Mn modified CaO catalyst₂，CO₂Is absorbed by Mn-CaO; oxidizing residual CO in the flue gas into CO by air₂，CO₂Is absorbed by Mn-CaO.

In the invention, the oxygen-enriched combustion of the coal or the biomass not only supplies energy for the calcination of Mn-CaO, but also can generate unburned coal coke or biomass coke; the coal coke or the biomass coke reacts with oxygen in the flue gas to generate CO and CO₂(ii) a CO is used as a denitration reducing agent, and Mn is used for synergistically removing NO/CO₂The catalyst is used as a bifunctional additive in the process, can catalyze CO denitration, and can promote CaO to capture CO₂(ii) a Therefore, in the calcium cycle carbonation stage, CO is denitrated under the catalysis of MnO in Mn modified CaO, and CO generated by CO denitration₂CO produced by oxidation of coke and CO₂And CO in flue gas₂Are all adsorbed and removed by Mn modified CaO, and finally, the high-efficiency synergistic removal of NO/CO is realized in a calcium-circulating carbonating furnace₂。

One or more technical schemes of the invention have the following beneficial effects:

CO generated by oxidizing coal coke or biomass coke is used as a reducing agent, a denitration reducing agent and an additional denitration reactor are not required to be added, Mn modification treatment is carried out on a calcium-based absorbent in the existing calcium circulation system, and CO in flue gas of a coal-fired power plant is realized in a carbonation reactor of calcium circulation₂High-efficiency removal of NO and denitration efficiency up to 99 percent, and CO₂The trapping efficiency is as high as 88%.

The Mn modified calcium-based absorbent is prepared by an isometric impregnation method, the modification process is simple, and the industrial application is easy.

Compared with other denitration technologies, the denitration technology provided by the invention does not need to add a denitration reducing agent and a reactor, only utilizes CO in the carbonation furnace as a reducing agent and Mn-CaO as a catalyst to carry out denitration, and has the advantages of high denitration efficiency, extremely low economic cost, centralized reactor and high space utilization rate; Mn-CaO flows repeatedly in the calcining and carbonating furnace, and the catalyst can be repeatedly utilized.

CO generated in process of catalyzing CO denitration by Mn-CaO₂Can be absorbed by Mn-CaO in the carbonator without generating additional CO₂And (4) emission, namely a denitration technology with zero carbon emission.

The CO generated in the calcium circulation is recycled, so that the problem of CO emission in the carbonating furnace tail gas is solved; realizing CO in flue gas of coal-fired boiler in same reactor₂And NO removal, so that the simultaneous removal of various pollutants is realized.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 shows the CO/Mn-CaO and CO/CaO synergistic NO/CO removal₂The comparison graph is as follows: 1(a) is the concentration of NO at the outlet of the fluidized bed reactor, and 1(b) is the concentration of CO at the outlet of the fluidized bed reactor₂The concentration (in a fluidized bed reactor, CaO and Mn-CaO are respectively obtained by calcining limestone and manganese acetate modified limestone, the mass of the calcium-based absorbent is 16g, the fluidization number is 2, the Mn/Ca molar ratio in the Mn-CaO is 3.5:100, the calcining temperature is 850 ℃, and the calcining temperature is 21 percent of O₂/N₂And the synergistic removal condition is as follows: 650 ℃ and 0.05% O₂0.5% CO/500ppm NO/0 or 15% CO₂/N₂)。

FIG. 2 shows the synergistic NO/CO removal₂XRD analysis patterns of the front and back Mn-CaO (Mn/Ca molar ratio in Mn-CaO is 3.5: 100).

FIG. 3 is a Mn/Ca molar ratio CO/Mn-CaO synergistic NO/CO removal₂The influence of (a): 3(a) CO₂Concentration, 3(b) NO concentration (fluidized bed reactor, Mn-CaO mass 16g, fluidization number 2, calcination: 850 ℃, 21% O₂/N₂And the synergistic removal condition is as follows: 650 ℃ and 0.05% O₂/0.4％CO/500ppm NO/15％CO₂/N₂)。

FIG. 4 shows the CO concentration vs. CO/Mn-CaO for the synergistic NO/CO removal₂The influence of (a): 4(a) CO₂Concentration, 4(b) NO concentration (fluidized bed reactor, Mn-CaO mass 16g, fluidization number 2, Mn/Ca molar ratio in Mn-CaO 3.5:100,and (3) calcining: 850 ℃ and 21% O₂/N₂And the synergistic removal condition is as follows: 650 ℃ and 0.05% O₂/2000-5000ppm CO/500ppm NO/15％CO₂/N₂)。

FIG. 5 shows the carbonation temperature for CO/Mn-CaO removal of NO/CO synergistically₂The influence of (a): 5(a) CO₂Concentration, 5(b) NO concentration (fluidized bed reactor, Mn-CaO mass 16g, fluidization number 2, Mn/Ca molar ratio in Mn-CaO 3.5:100, calcination: 850 ℃, 21% O₂/N₂And the synergistic removal condition is as follows: 0.05% O₂/0.4％CO/500ppm NO/15％CO₂/N₂)。

FIG. 6 shows the synergistic removal of NO/CO from CO/Mn-CaO by the number of calcium cycles₂The influence of (a): 6(a) CO₂Concentration, 6(b) NO concentration (fluidized bed reactor, Mn-CaO mass 16g, fluidization number 2, Mn/Ca molar ratio in Mn-CaO 3.5:100, calcination: 850 ℃, 21% O₂/N₂And the synergistic removal condition is as follows: 650 ℃ and 0.05% O₂/0.4％CO/500ppm NO/15％CO₂/N₂)。

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The invention provides a method for simultaneously removing CO by utilizing Mn-CaO and CO based on calcium circulation₂And NO_xThe method adopts coal or biomass oxygen-enriched combustion to supply energy for Mn-CaO calcination in a calcination furnace, the materials in the furnace are in fast fluidization, and Mn-CaWhen O flows into the carbonator from the calciner, unburned coal coke or biomass coke is carried;

simultaneous CO generation in carbonation furnaces₂Capturing and removing NO, and reacting coal coke or biomass coke with oxygen in flue gas in a furnace to generate CO and CO₂(see reactions (3) and (4)), coke is oxidized with O in the dense phase zone₂And NO_xExhaustion; NO is reduced into N by CO under the catalysis of Mn-CaO₂(see reactions (5) and (6)); CO in the furnace₂Is absorbed by Mn-CaO (see reaction (2)); the dilute phase zone in the furnace is provided with an air inlet which is connected with an air source, so that the residual CO in the flue gas can be oxidized into CO conveniently₂(see reaction (7)) CO₂Is absorbed by Mn-CaO in the dilute phase zone.

The reaction mechanism of the present invention is as follows:

CaCO₃→CaO+CO₂ (1)

CaO+CO₂→CaCO₃ (2)

C+O₂→CO₂ (3)

2C+O₂→2CO (4)

2CO+O₂→2CO₂ (7)

in one embodiment of the invention, a synergistic CO removal based on calcium cycling is provided₂And NO, said method being:

(2) the coal coke or the biomass coke reacts with oxygen in the flue gas to generate CO and CO₂Coke quiltO₂And NO_xExhaustion; the NO is reduced into N by CO under the catalysis of the Mn modified CaO catalyst₂(ii) a CO in the furnace₂Is absorbed by Mn-CaO; oxidizing residual CO in the flue gas into CO by air₂，CO₂Is absorbed by Mn-CaO.

In one or more embodiments, the Mn/Ca molar ratio is 2.5 to 4: 100; preferably 2.5: 100; 3:100, 3.5:100, 4: 100; further preferably 3.5: 100;

in one or more embodiments, the Mn-modified CaO catalyst is prepared by: dipping limestone particles into a manganese salt solution with the same volume, and drying and calcining to prepare Mn modified CaO, which is recorded as Mn-CaO;

preferably, Mn in the Mn-CaO is present in the form of MnO;

in one or more embodiments, the manganese salt is selected from: one or more of manganese acetate, manganese chloride, manganese sulfate and manganese nitrate;

in one or more embodiments, the concentration of CO participating in the denitrification reaction is greater than 0.25%, preferably between 0.25% and 0.5%; further preferably 0.25%, 0.3%, 0.4%, 0.5%;

in one or more embodiments, step (1) is performed in a calciner;

in one or more embodiments, step (2) is performed in a carbonation furnace;

preferably, the reaction temperature in the carbonation furnace is 600 ℃ to 700 ℃, preferably 600 ℃, 650 ℃, 700 ℃, and more preferably 650 ℃.

Preferably, the calcining atmosphere in the calcining furnace is oxygen-enriched atmosphere;

in one or more embodiments, the biomass is selected from the group consisting of: rice hulls, straw, trees, or mixtures thereof; in the embodiment of the present invention, the kind of the biomass is not particularly limited.

According to the invention, the oxygen-enriched combustion of the coal or biomass not only supplies energy for Mn-CaO calcination, but also can generate unburned coal coke or biomass coke; the coal coke or the biomass coke reacts with oxygen in the flue gas to generate CO and CO₂(ii) a CO is used as a denitration reducing agent, and Mn is inSynergistic NO/CO removal₂The catalyst is used as a bifunctional additive in the process, can catalyze CO denitration, and can promote CaO to capture CO₂(ii) a Therefore, in the calcium cycle carbonation stage, CO is denitrated under the catalysis of MnO in Mn modified CaO, and CO generated by CO denitration₂CO produced by oxidation of coke and CO₂And CO in flue gas₂Are all adsorbed and removed by Mn modified CaO, and finally, the high-efficiency synergistic removal of NO/CO is realized in a calcium-circulating carbonating furnace₂Denitration efficiency is up to 99%, CO₂The trapping efficiency is as high as 88%.

The invention will be further explained and illustrated with reference to specific examples.

Example 1

Research on CO/Mn-CaO synergistic removal of NO/CO on bubbling fluidized bed experiment table₂The performance of (A):

oxygen-enriched combustion of coal or rice hulls and straws is adopted in the calcining furnace to supply energy for calcining Mn-CaO, materials in the furnace are in fast fluidization, and unburned coal coke or biomass coke is carried when Mn-CaO flows into the carbonating furnace from the calcining furnace;

simultaneous CO generation in carbonation furnaces₂Trapping and NO removal: in the furnace, the coal coke or biomass coke reacts with oxygen in the flue gas to produce CO and CO₂In the dense phase zone, the coke is coated with O₂And NO_xExhaustion; NO is reduced into N by CO under the catalysis of Mn-CaO₂(ii) a CO in the furnace₂Is absorbed by Mn-CaO; the dilute phase zone in the furnace is provided with an air inlet which is connected with an air source, so that the residual CO in the flue gas can be oxidized into CO conveniently₂，CO₂Is absorbed by Mn-CaO in a dilute phase region; Mn-CaO in the carbonating furnace enters a calcining furnace to carry out calcining reaction, thereby realizing the regeneration of CaO and CO₂Enriching;

the Mn/Ca molar ratio in this example was 3.5: 100; the concentration of CO participating in the denitration reaction in the carbonating furnace is 0.25%; the reaction temperature in the carbonation furnace was 650 ℃.

Example 2

Differs from example 1 in that the Mn/Ca molar ratio is 2.5: 100;

example 3

The difference from example 1 is that the Mn/Ca molar ratio is 3: 100;

example 4

The difference from example 1 is that the Mn/Ca molar ratio is 4: 100;

example 5

The difference from example 1 is that the CO concentration in the carbonation furnace participating in the denitration reaction is 0.2%;

example 6

The difference from example 1 is that the CO concentration in the carbonation furnace participating in the denitration reaction is 0.3%;

example 7

The difference from example 1 is that the CO concentration in the carbonation furnace participating in the denitration reaction is 0.4%;

example 8

The difference from example 1 is that the CO concentration in the carbonation furnace participating in the denitration reaction is 0.5%;

example 9

The difference from example 1 is that the reaction temperature in the carbonation furnace is 600 ℃;

example 10

The difference from example 1 is that the reaction temperature in the carbonation furnace is 700 ℃;

comparative example 1

CO/CaO synergetic removal of NO/CO is explored on a bubbling fluidized bed experiment table₂The performance of (c).

Comparative example 1 differs from example 1 in that the catalyst used is not Mn — CaO, but CaO.

As shown in FIG. 1(a), CO in the carbonation kinetics control stage of Mn-CaO₂The concentration was about 2.0% and was about 46% lower than CaO. Eta of Mn-CaO_CO2About 88% higher than CaO by 21%. Mn-CaO has higher CO than CaO under bubbling fluidization₂The collection efficiency; as shown in FIG. 1(b), when CaO is not carbonated (atmosphere is free of CO)₂) The NO concentration was about 350ppm and remained stable over 900 s. Although CaO catalyzes CO denitration, η_NOIt is only 31%. When CaO is carbonated (atmosphere containing CO)₂) The NO concentration rises rapidly to about 560ppm and remains around 560ppm during the CaO carbonation kinetics control phase. Indicating that CaO cannot catalyze CO denitration at the same time as carbonation at 650 ℃ and CO concentration of only 0.4%. When NO carbonation of Mn-CaO occurred, the NO concentration increased substantially to 465ppm within 50s, then decreased rapidly to 0ppm within 300s, and remained stable at 900 s. Although the initial Mn-CaO catalytic CO denitration performance fluctuates, the catalytic CO denitration performance is stable and 100% denitration is realized within 300-900s, which is far higher than the efficiency of CaO catalytic CO denitration under the same conditions. This indicates that Mn strongly catalyzes CO denitration. When the Mn-CaO is carbonated, the NO concentration fluctuates in 300s similarly to the case when the Mn-CaO is not carbonated, and after 300s, the NO concentration is kept at about 5ppm eta in the Mn-CaO carbonation kinetics control stage_NOCan reach 99 percent, and has the efficiency close to that of catalyzing CO denitration when the Mn-CaO is not carbonated. Therefore, the carbonation reaction has no obvious influence on the CO denitration catalyzed by Mn-CaO. The adverse effect of CaO inactivation on CO denitration is greatly reduced by Mn modification. In conclusion, Mn not only promotes decarbonization under CaO fluidization and catalyzes CO denitration in a carbonating furnace, but also is a high-efficiency bifunctional additive.

XPS was used to test the valence state of Mn before and after catalytic CO denitration by Mn-CaO using the same Mn-CaO as in example 1 on the bubbling fluidized bed reactor mentioned in example 1, and the results are shown in FIG. 2. When the calcining atmosphere is 21 percent of O₂/N₂When Mn2p (3/2) and Mn2p (1/2) peaks were at 641.6eV and 653.2eV, respectively, indicating that the manganese oxide was Mn₃O₄. The main manganese oxide in Mn-CaO before the denitration of CO uncatalyzed is Mn₃O₄. After denitration by catalyzing CO by Mn-CaO, Mn2p (3/2) and Mn2p (1/2) peaks are respectively positioned at 641.3eV and 653.4eV, and the manganese oxide is MnO. After the CO denitration is catalyzed by the Mn-CaO, MnO is a main manganese oxide in the Mn-CaO. From this, it is presumed that Mn is present in the process of denitration of CO catalyzed by Mn-CaO₃O₄Gradually converted to MnO by reaction with CO. In the actual calcium cycle, Mn-CaO is mainly Mn due to the oxygen-rich environment in the calciner₃O₄And (3) modifying CaO. When Mn is present₃O₄After the modified CaO enters the carbonating furnace, a large amount of CO generated by the oxidation of the unburned coke can convert Mn into Mn in a short time₃O₄To MnO. Furthermore, the calciner inflowing fresh Mn compared to the large amount of calcium based sorbent in the carbonator₃O₄Modified CaO occupies only a small proportion. It is presumed that a large amount of Mn-CaO which has been converted into MnO-modified CaO and a high concentration of CO can realize efficient and stable denitration.

The synergistic NO/CO removal from a bubbling fluidized bed reactor as mentioned in example 1, using the same Mn-CaO as in example 1, by studying the Mn/Ca molar ratio and the CO/Mn-CaO through examples 1 to 4₂The results are shown in FIG. 3. In order to explore the influence of the stable catalytic stage of Mn-CaO on CO denitration, the calcined Mn-CaO was adjusted to 0.4% CO/N₂Pretreating in the atmosphere for about 2min, and then cooperatively removing NO/CO₂The experiment of (1); as shown in FIG. 3(a), as the Mn/Ca molar ratio was increased from 2.5:100 to 3.5:100, CO was present in the control stage of the carbonation kinetics of Mn-CaO₂The concentration is reduced from about 3.3 percent to 2.0 percent eta_CO2The yield is improved from 82% to 88%. As shown in FIG. 4(b), when the Mn/Ca molar ratio was increased from 2.5:100 to 3.5:100, the NO concentration was decreased from about 109ppm to 5ppm, eta_NOFrom 80% to 99% (t 730 s). The Mn/Ca molar ratio in Mn-CaO is increased, so that active sites for catalyzing CO catalytic denitration are increased, CO denitration is promoted, and meanwhile, the Mn/Ca molar ratio is increased to enhance the effect of gathering CO from CaO₂The positive effect of the composition. And eta of the kinetic control phase when the Mn/Ca molar ratio is further increased to 4:100_CO2And η_NORespectively to 85% and 94%. Further increase of Mn content in Mn-CaO leads to CO₂The trapping performance and the denitration performance are lowered. Mn blocks a part of the pore channels and blocks CO, NO and CO₂Diffusion in Mn-CaO for catalytic CO denitration and CO capture₂With adverse effects. In general, the positive effects of Mn on carbon capture and CO denitration can offset the negative effects of these blockages. However, when the Mn/Ca molar ratio exceeds 4:100, the adverse effect is more pronouncedSevere, that is η_CO2And η_NOThe cause of the drop. To realize high-efficiency CO₂For capture and CO denitration, a suitable Mn/Ca molar ratio is 3.5: 100.

The CO concentration vs. CO/Mn-CaO synergistic NO/CO removal on a bubbling fluidized bed reactor as mentioned in example 1 was investigated by examples 5-8 using the same Mn-CaO as in example 1₂The results are shown in FIG. 4. In order to explore the influence of the stable catalytic stage of Mn-CaO on CO denitration, the calcined Mn-CaO was adjusted to 0.4% CO/N₂Pretreating in the atmosphere for about 2min, and then cooperatively removing NO/CO₂The experiment of (1). As shown in FIG. 4(a), when the CO concentration is 0.2-0.5%, CO in the Mn-CaO carbonation kinetics control stage₂The concentration is kept around 2.0%. CO concentration difference for capturing CO from Mn-CaO₂No influence is produced. As shown in fig. 4(b), the NO concentration in the kinetic control phase drops sharply when the CO concentration increases from 0.2% to 0.3%, for example from 170ppm to 16ppm at 600 s. With the increase of the CO concentration, the efficiency and the stability of CO denitration under the catalysis of Mn-CaO are improved. The duration of NO below 5ppm increased from 600s to 730s as the CO concentration increased from 0.3% to 0.5%. In the carbonation kinetics control stage of Mn-CaO, the stable and efficient denitration under the catalysis of Mn-CaO can be realized by the CO concentration of more than 0.25%. Therefore, in the practical application of calcium cycle, Mn is converted when CO is used₃O₄After the conversion to MnO, the concentration of the residual CO in the carbonating furnace is above 0.25%, which is enough to realize high-efficiency denitration under the catalysis of Mn-CaO.

The CO/Mn-CaO synergistic removal of NO/CO by carbonation temperature on a bubbling fluidized bed reactor as mentioned in example 1 was investigated by examples 9 and 10 using the same Mn-CaO as in example 1₂The results are shown in FIG. 5. In order to explore the influence of the stable catalytic stage of Mn-CaO on CO denitration, the calcined Mn-CaO was adjusted to 0.4% CO/N₂Pretreating in the atmosphere for about 2min, and then cooperatively removing NO/CO₂The experiment of (1). As shown in FIG. 5(a), as the carbonation temperature increased from 600 to 700 deg.C, CO was present during the Mn-CaO carbonation kinetics control stage₂Increasing the concentration from about 0.8% to about 6.1%, eta of Mn-CaO_CO2From 96% to 67%. As shown in fig. 5(b), when the temperature was 600 ℃, the NO concentration was maintained below 5ppm for 50s and then increased with time. The denitration of the Mn-CaO catalyzed CO at 600 ℃ is unstable and low in efficiency. The NO concentration was maintained below 5ppm for about 730s and 900s at 650 and 700 c, respectively; the high temperature is favorable for the denitration of CO catalyzed by Mn-CaO; Mn-CaO can efficiently and stably catalyze CO denitration at 650 ℃, and simultaneously realize efficient CO denitration₂Trapping, so 650 ℃ is the optimum temperature.

In the calcium circulation, the calcium-based absorbent repeatedly circulates in the carbonator and the calciner. FIG. 6 shows the effect of the number of calcination/carbonation cycles on Mn-CaO catalyzed CO denitration during carbonation. As shown in FIG. 6(a), CO in the Mn-CaO carbonation kinetics control stage increases from 1 to 10 cycles₂The concentration is kept at about 2.0 percent eta_CO2The retention was 88%. As shown in FIG. 6(b), the NO concentration in the kinetic control phase was always maintained at about 5ppm, η, as the number of cycles was increased from 1 to 10_NOAll are about 99 percent. Although the number of cycles is applied to the eta of the kinetic control phase_CO2And η_NOThe effect was not great, but as the number of cycles increased from 1 to 10, the duration of the kinetic control phase of Mn-CaO decreased from 730s to about 300 s. The duration of the kinetic control phase was reduced by 200s, 80s and 60s when the number of cycles was increased from 1 to 3, 4 to 6, 7 to 10, respectively. The decay in the duration of the carbonation kinetics control phase gradually slows as the number of calcium cycles increases. Considering only the short residence time of the sample in the carbonator, it can be speculated that even after more than 10 calcium cycles, Mn-CaO can still efficiently catalyze CO denitration and efficiently capture CO in the residence time₂。

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1.Synergistic CO removal based on calcium circulation₂And NO, characterized in that the process is:

(2) the coal coke or the biomass coke reacts with oxygen in the flue gas to generate CO and CO₂Coke quilt O₂And NO_xExhaustion; the NO is reduced into N by CO under the catalysis of the Mn modified CaO catalyst₂，CO₂Absorbed by the Mn modified CaO catalyst; oxidizing residual CO in the flue gas into CO by air₂，CO₂Absorbed by the Mn modified CaO catalyst.

2. Synergistic CO removal based on calcium cycling according to claim 1₂And NO, characterized in that the Mn/Ca molar ratio is 2.5-4: 100; preferably 2.5: 100; 3:100, 3.5:100, 4: 100.

3. Synergistic CO removal based on calcium cycling according to claim 1₂And NO, and is characterized in that the preparation method of the Mn modified CaO catalyst comprises the following steps: and (3) dipping limestone particles into an isometric manganese salt solution, and drying and calcining to obtain the catalyst.

4. Synergistic CO removal based on calcium cycling according to claim 1₂And NO, characterized in that Mn is present in the Mn modified CaO catalyst in the form of MnO.

5. Synergistic CO removal based on calcium cycling according to claim 1₂And NO, characterized in that the manganese salt is selected from: one or more of manganese acetate, manganese chloride, manganese sulfate and manganese nitrate.

6. Synergistic CO removal based on calcium cycling according to claim 1₂And NO, characterized in that the concentration of CO participating in the denitration reaction is higher than 0.25%, preferably 0.25% -0.5%; more preferably 0.25%, 0.3%, 0.4%, 0.5%.

7. Synergistic CO removal based on calcium cycling according to claim 1₂And NO, characterized in that step (1) is carried out in a calciner and step (2) is carried out in a carbonator.

8. Synergistic CO removal based on calcium cycling according to claim 1₂And NO, characterized in that, preferably, the reaction temperature in the carbonation furnace is between 600 ℃ and 700 ℃, preferably between 600 ℃, 650 ℃, 700 ℃.

9. Synergistic CO removal based on calcium cycling according to claim 1₂And NO, characterized in that, preferably, the calcining atmosphere in the calcining furnace is an oxygen-rich atmosphere.

10. Synergistic CO removal based on calcium cycling according to claim 1₂And NO, characterized in that the biomass is selected from the group consisting of: rice hulls, straw, trees, or mixtures thereof.