Flue gas circulation treatment system and method

Abstract

The invention provides a flue gas circulation treatment system and method. The system comprises a pretreatment module, an electrochemical conversion module, an enrichment and regeneration module, an ammonia gas utilization module and a combustion system, the pretreatment module is used for sequentially pretreating and absorbing flue gas to obtain a first absorption solution containing nitrate; wherein the pretreated flue gas is absorbed by a first solution; the electrochemical conversion module comprises an electrochemical reactor, and the electrochemical reactor is used for performing electrochemical reduction on oxynitride in the first absorption solution to obtain a first product containing ammonia gas; the enriching and regenerating module is used for separating the first product to obtain ammonia gas and regenerated electrolyte; the ammonia gas utilization module is used for storing ammonia gas; the combustion system is used for conducting blending combustion on ammonia gas and fuel. According to the system disclosed by the invention, nitrogen circulation is established by an electrochemical method, and the coal consumption and the carbon emission level are reduced while nitrogen oxides are recycled.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and in particular to a system and method for circulating flue gas treatment. Background Art

[0002] In recent years, as traditional industries have shifted towards clean development, in order to reduce coal consumption and carbon emissions, the demand for coal-fired units to use green ammonia for power generation has gradually increased.

[0003] Since industrial boilers in the coal-fired power industry will produce flue gas containing nitrogen oxides after burning fossil fuels, the denitrification process is essential to avoid significant environmental impact. Currently, flue gas is mainly denitrified using selective catalytic reduction technology (SCR), but SCR technology currently mainly converts nitrogen oxides into nitrogen (N2). This SCR technology not only has a high reaction temperature, but also does not enable the recycling of nitrogen oxides.

[0004] In recent years, technologies such as water electrolysis for hydrogen production, electrochemical carbon dioxide reduction, and electrochemical ammonia synthesis have developed rapidly. Among them, the electrochemical ammonia synthesis reaction has developed a relatively rich catalytic system, which can realize ammonia synthesis using nitrogen gas and nitrates as nitrogen sources, and needs to be further developed towards industrial application.

[0005] The Chinese patent application with the patent application publication number CN112920087A provides a method and system for preparing urea by coupling denitration with electrocatalytic reduction, especially for the purification of nitrogen oxides in industrial flue gas and the resource treatment of nitrogen, that is, an electrochemical reduction method is used to combine CO2 with a solution rich in nitrite and nitrate for electrochemical co-reduction to obtain urea. However, this method does not involve technologies such as synthesis of ammonia from nitrogen oxides and nitrogen recycling.

[0006] The Chinese patent application with the patent application publication number CN111533220A provides a technical solution for the electrocatalytic reduction of nitrate in water, and its main target product is ammonia nitrogen. However, the technical solution does not consider how to combine it with the removal process of nitrogen oxides in flue gas.

[0007] Therefore, in order to solve the above problems, it is urgent to develop a treatment system that can convert nitrogen oxides in flue gas and realize the recycling of nitrogen oxides. Summary of the invention

[0008] The main purpose of the present invention is to provide a system and method for flue gas recycling treatment to solve the problems of low nitrogen oxide conversion rate in flue gas and inability to achieve nitrogen recycling in the prior art.

[0009] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a system for flue gas circulation treatment is provided, which system comprises: a pretreatment module, an electrochemical conversion module, an enrichment and regeneration module, an ammonia utilization module and a combustion system, wherein the pretreatment module has a first inlet and a first outlet, the first inlet is connected to a flue gas source, and the pretreatment module is used to pretreat and absorb the flue gas in sequence to obtain a first absorption solution containing nitrate; wherein the pretreated flue gas is absorbed by the first solution; the electrochemical conversion module comprises an electrochemical reactor, the electrochemical reactor has a second inlet and a second outlet, the second inlet is connected to the first outlet, and the electrochemical reactor The reactor is used for electrochemically reducing nitrogen oxides in the first absorption solution to obtain a first product containing ammonia; the enrichment and regeneration module has a third inlet and a third outlet, the third inlet is connected to the second outlet, and the enrichment and regeneration module is used to separate the first product to obtain ammonia and a regenerated electrolyte; the ammonia utilization module has a fourth inlet and a fourth outlet, the fourth inlet is connected to the third outlet, and the ammonia utilization module is used to store ammonia; the ammonia utilization module also has an ammonia outlet; the combustion system has a fifth inlet and a fifth outlet, the fifth inlet is connected to the ammonia outlet, and the combustion system is used to mix ammonia with fuel; the fifth outlet is connected to the first inlet.

[0010] Further, the pretreatment module also includes a dust removal device, a plasma treatment device and an absorption device connected in sequence; the dust removal device is used to remove dust from the flue gas to obtain dust-removed flue gas; and / or, the dust removal device is selected from any one or more of a bag dust collector, an electrostatic precipitator, an electric bag combined dust collector, a wet dust collector, a mechanical dust collector and a cyclone dust collector; and / or, the outlet temperature of the dust removal device is 75-85°C; and / or, the mass proportion of dust in the dust-removed flue gas is <0.01%; the plasma treatment device is used to perform plasma treatment on the dust-removed flue gas to obtain pretreated flue gas; and / or, the plasma generation method in the plasma treatment device is selected from any one or more of DBD discharge, microwave discharge, spark discharge, sliding arc discharge and rotating sliding arc discharge; and / or, a mixture including water vapor and oxygen is introduced for plasma treatment, and the ratio of the feed amount of the mixture to the feed amount of the dust-removed flue gas is 10-200:250000kg / Nm 3 ; The absorption device is used to absorb the pretreated flue gas through the first solution to obtain a first absorption solution; and / or, the pressure in the absorption device is 3 to 20 bar, and / or, the ratio of the feed amount of the first solution to the feed amount of the pretreated flue gas is 200 to 500:230000 kg / Nm 3 .

[0011] Furthermore, the electrochemical reactor is a high-pressure reaction vessel and / or a flow-type reaction vessel; the high-pressure reaction vessel is a diaphragm-free reaction vessel, the pressure in the high-pressure reaction vessel is 1 to 10 bar, and H2 and N2 are introduced every 10 to 20 hours to provide pressure; and / or, the pressure in the flow-type reaction vessel is 1 to 5 bar; the diaphragm of the flow-type reaction vessel is an anion exchange membrane and / or a bipolar membrane; and / or, the anion exchange membrane is selected from polyaryl membranes, polyarylether membranes, polyethylene membranes, polystyrene membranes, polytetrafluoroethylene membranes and polyvinyl chloride membranes modified with cationic groups. Any one or more of the benzene membrane, and / or, the source of the cationic group is selected from any one or more of polyalkylammonium salts, imidazolium salts, pyridinium salts and piperidinium salts; and / or the polyalkylammonium salt is selected from any one or more of triethyl quaternary ammonium salt, trimethyl quaternary ammonium salt and tributyl quaternary ammonium salt; and / or, the cation exchange membrane in the bipolar membrane is a perfluorosulfonic acid resin, and the monomer forming the perfluorosulfonic acid resin is selected from any one or more of potassium perfluoro-1-octanesulfonate, potassium perfluoro-1-butanesulfonate, potassium perfluoro-1-hexanesulfonate and sodium perfluoro-1-pentanesulfonate.

[0012] Furthermore, the cathode catalytic material of the electrochemical reactor is selected from any one or more of metal element catalysts corresponding to transition metals, metal oxide catalysts corresponding to transition metals, and single metal atom catalysts; and / or, the transition metals in the metal element catalysts and the metal oxide catalysts are each independently selected from any one or more of Cu, Fe, Ru, Co, and Au; and / or, the single metal atom catalyst is selected from any one or more of Cu atoms, Fe atoms, Ti atoms, Ru atoms, and V atoms.

[0013] Furthermore, the above system also includes a heat storage module, which adopts a sensible heat storage method and / or a phase change heat storage method, and is used to provide heat to the enrichment and regeneration module.

[0014] According to another aspect of the present invention, there is provided a method for treating flue gas using the above-mentioned system, the method comprising: pre-treating the flue gas and absorbing the pre-treated flue gas with a first solution to obtain a first absorption solution containing nitrates; reducing nitrogen oxides in the first absorption solution by an electrochemical reaction to obtain a first product containing ammonia; separating the first product to obtain ammonia and a regenerated electrolyte; and blending the ammonia with a fuel to generate combustion flue gas, wherein the flue gas includes combustion flue gas.

[0015] Furthermore, the pretreatment also includes: removing dust from the flue gas to obtain dust-removed flue gas; subjecting the dust-removed flue gas to plasma treatment to obtain pretreated flue gas; wherein the residence time of the dust removal is 2 to 30 seconds; preferably, a mixture including water vapor and oxygen is introduced for plasma treatment, and the molar ratio of water vapor to oxygen is 1 to 20:1; and / or, the treatment time of the plasma treatment is 0.2 to 1 minute; and / or, the power of the plasma treatment is 200 to 5000W.

[0016] Furthermore, the first solution is selected from any one or more of a strong alkaline solution, a neutral solution and a weak alkaline solution, the strong alkaline solution is selected from any one or more of a sodium hydroxide solution, a potassium hydroxide solution and a calcium hydroxide solution, the weak alkaline solution is a phosphate buffer solution and / or a hydrogen phosphate buffer solution, and the neutral solution is selected from any one or more of a sodium sulfate solution, a sodium potassium sulfate solution, a sodium nitrate solution and a potassium nitrate solution.

[0017] Further, the ammonia in the first product is subjected to acid treatment and first gas-liquid separation in sequence to obtain first ammonia; wherein the temperature of the acid treatment is -20 to 10°C, the solution of the acid treatment is 0.1 to 3 mol / L sulfuric acid solution and / or 0.1 to 3 mol / L hydrochloric acid solution, and the temperature of the first gas-liquid separation is 70 to 90°C; and / or, the liquid ammonia in the first product is subjected to second gas-liquid separation to obtain second ammonia, the temperature of the second gas-liquid separation is 150 to 200°C, and the pressure of the second gas-liquid separation is 1 to 5 bar; and / or, the first gas-liquid separation and the second gas-liquid separation are performed by heating.

[0018] Furthermore, the mass content of ammonia in the blending is 3-10%; and / or the flue gas includes nitrogen oxides, and the mass concentration of nitrogen oxides is 40-1000 mg / Nm 3 .

[0019] By applying the technical solution of the present invention, the flue gas circulation treatment system of the present invention is aimed at the fossil fuel energy / heating scenario and the ammonia combustion demand in coal-fired power generation. It can use the nitrogen oxides in the flue gas as a nitrogen source to produce high-purity ammonia, and burn the ammonia with ammonia, which not only establishes a nitrogen cycle by an electrochemical method, but also reduces coal consumption and carbon emission levels while realizing the recycling of nitrogen oxides. Specifically, the flue gas purification and the enrichment of nitrogen oxides can be achieved through the pretreatment module. The nitrogen oxides in the first absorption solution (the main component of which is a nitrate solution) are converted by an electrochemical reactor to achieve ammonia synthesis. While obtaining ammonia through the enrichment and regeneration module, the regeneration of the electrolyte is also achieved. Through the ammonia utilization module, a part of the ammonia can directly enter the combustion system and be co-combusted with the fuel to realize the nitrogen cycle, and the other part of the ammonia can also be stored in the form of liquid ammonia for other purposes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 A schematic diagram of a flue gas circulation treatment system of the present application is shown;

[0022] Figure 2 A schematic diagram of a preprocessing module of the present application is shown;

[0023] Figure 3 A schematic diagram of the electrochemical reactor of the present application is shown.

[0024] Among them, the above drawings include the following reference numerals:

[0025] 01. Electrochemical reactor; 02. Dust removal device; 03. Plasma treatment device; 04. Absorption device; 011. External power supply; 012. Working electrode; 013. Reference electrode; 014. Counter electrode; 015. Stirring magnet; 016. Cathode gas diffusion electrode; 017. Ion exchange membrane; 018. Anode gas diffusion electrode; 10. Pretreatment module; 20. Electrochemical conversion module; 30. Enrichment and regeneration module; 40. Ammonia utilization module; 50. Heat storage module; 60. Combustion system; a. High-pressure reaction vessel; b. Flow reaction vessel. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] As analyzed in the background technology of this application, the prior art has the problems of low conversion rate of nitrogen oxides in flue gas and inability to achieve nitrogen recycling. In order to solve the above problems, this application provides a system and method for flue gas recycling treatment.

[0028] In a typical embodiment of the present application, a system for flue gas circulation treatment is provided, such as Figure 1As shown, the system includes: a pretreatment module 10, an electrochemical conversion module 20, an enrichment and regeneration module 30, an ammonia utilization module 40 and a combustion system 60, the pretreatment module 10 has a first inlet and a first outlet, the first inlet is connected to the flue gas source, the pretreatment module 10 is used to pretreat and absorb the flue gas in sequence to obtain a first absorption solution containing nitrate; wherein the pretreated flue gas is absorbed by the first solution; the electrochemical conversion module 20 includes an electrochemical reactor 01, the electrochemical reactor 01 has a second inlet and a second outlet, the second inlet is connected to the first outlet, and the electrochemical reactor 01 is used to absorb the first absorption solution The nitrogen oxides are electrochemically reduced to obtain a first product containing ammonia; the enrichment and regeneration module 30 has a third inlet and a third outlet, the third inlet is connected to the second outlet, and the enrichment and regeneration module 30 is used to separate the first product to obtain ammonia and a regenerated electrolyte; the ammonia utilization module 40 has a fourth inlet and a fourth outlet, the fourth inlet is connected to the third outlet, and the ammonia utilization module 40 is used to store ammonia; the ammonia utilization module 40 also has an ammonia outlet; the combustion system 60 has a fifth inlet and a fifth outlet, the fifth inlet is connected to the ammonia outlet, and the combustion system 60 is used to mix ammonia with fuel; the fifth outlet is connected to the first inlet.

[0029] The flue gas circulation treatment system of the present invention is aimed at the fossil fuel energy / heating scenario and the demand for ammonia combustion in coal-fired power generation. It can use nitrogen oxides in flue gas as a nitrogen source to produce high-purity ammonia, and burn ammonia with ammonia. It not only establishes a nitrogen cycle by an electrochemical method, but also reduces coal consumption and carbon emissions while realizing the recycling of nitrogen oxides. Specifically, the pretreatment module 10 can be used to purify the flue gas and enrich nitrogen oxides. The nitrogen oxides in the first absorption solution (the main component of which is a nitrate solution) are converted by the electrochemical reactor 01 to achieve ammonia synthesis. Ammonia is obtained by the enrichment and regeneration module 30, and the regeneration of the electrolyte is also achieved. Through the ammonia utilization module 40, a part of the ammonia can directly enter the combustion system 60 and be co-combusted with the fuel to realize the nitrogen cycle, and the other part of the ammonia can also be stored in the form of liquid ammonia for other purposes.

[0030] In one embodiment of the present application, the pretreatment module 10 further includes a dust removal device 02, a plasma treatment device 03 and an absorption device 04 connected in sequence; the dust removal device 02 is used to remove dust from the flue gas to obtain dust-removed flue gas; and / or, the dust removal device 02 is selected from any one or more of a bag dust collector, an electrostatic precipitator, an electric bag combined dust collector, a wet dust collector, a mechanical dust collector and a cyclone dust collector; and / or, the outlet temperature of the dust removal device 02 is 75 to 85°C; and / or, the mass of dust in the flue gas after dust removal is The ratio is less than 0.01%; the plasma treatment device 03 is used to perform plasma treatment on the dust-removed flue gas to obtain pre-treated flue gas; and / or, the plasma generation method in the plasma treatment device 03 is selected from any one or more of DBD discharge, microwave discharge, spark discharge, sliding arc discharge and rotating sliding arc discharge; and / or, a mixture including water vapor and oxygen is introduced for plasma treatment, and the ratio of the feed amount of the mixture to the feed amount of the dust-removed flue gas is 10-200:250000kg / Nm 3 ; The absorption device 04 is used to absorb the pretreated flue gas through the first solution to obtain a first absorption solution; and / or, the pressure in the absorption device 04 is 3 to 20 bar; and / or, the ratio of the feed amount of the first solution to the feed amount of the pretreated flue gas is 200 to 500:230000 kg / Nm 3 .

[0031] The above-mentioned type of dust removal device 02 is preferred, and the outlet temperature of the dust removal device 02 is controlled within the above-mentioned range, which helps to more efficiently remove dust from the flue gas, thereby reducing the dust mass ratio of the flue gas after dust removal, and making the mass ratio of dust in the flue gas after dust removal reach the above-mentioned range. It is preferred to introduce a mixture including water vapor and oxygen into the above-mentioned plasma treatment device 03 to perform plasma treatment on the flue gas after dust removal, and it is preferred to control the plasma generation mode and the ratio of the feed amount of the mixture to the feed amount of the flue gas after dust removal within the above-mentioned range, which helps to improve the plasma treatment efficiency, thereby improving the conversion rate of nitrogen oxides (containing nitrogen) in the flue gas. It is preferred to absorb the pretreated flue gas through the above-mentioned absorption device 04, and it is preferred to control the pressure in the absorption device 04 and the ratio of the feed amount of the first solution to the feed amount of the pretreated flue gas within the above-mentioned range, which helps to further enrich the nitrogen oxides and form the first absorption solution, thereby facilitating the subsequent electrochemical conversion of the first absorption solution.

[0032] In one embodiment of the present application, the electrochemical reactor 01 is a high-pressure reaction vessel and / or a flow-type reaction vessel; the high-pressure reaction vessel is a diaphragm-free reaction vessel, the pressure in the high-pressure reaction vessel is 1 to 10 bar, and H2 and N2 are introduced every 10 to 20 hours to provide pressure; and / or, the pressure in the flow-type reaction vessel is 1 to 5 bar; the diaphragm of the flow-type reaction vessel is an anion exchange membrane and / or a bipolar membrane; and / or, the anion exchange membrane is selected from polyaryl membranes modified with cationic groups, polyarylether membranes, polyethylene membranes, polystyrene membranes, polytetrafluoroethylene membranes and Any one or more of the polyphenyl membranes, and / or, the source of the cationic group is selected from any one or more of polyalkylammonium salts, imidazolium salts, pyridinium salts and piperidine salts, preferably piperidine salts; and / or the polyalkylammonium salt is selected from any one or more of triethyl quaternary ammonium salt, trimethyl quaternary ammonium salt and tributyl quaternary ammonium salt; and / or, the cation exchange membrane in the bipolar membrane is a perfluorosulfonic acid resin, and the monomers forming the perfluorosulfonic acid resin are selected from any one or more of potassium perfluoro-1-octanesulfonate, potassium perfluoro-1-butanesulfonate, potassium perfluoro-1-hexanesulfonate and sodium perfluoro-1-pentanesulfonate.

[0033] The high-pressure reaction vessel is preferably used and the pressure in the high-pressure reaction vessel is controlled within the above range. Intermittent synthesis of ammonia is performed with an external power supply in a working unit of 10 to 20 hours, which is helpful for the conversion of the nitrate solution in the first absorption solution. The flow-type reaction vessel is preferably used and the pressure in the flow-type reaction vessel and the type of diaphragm are controlled within the above range, which is helpful for the first absorption solution to continuously flow into the reactor cathode and enter the enrichment regeneration module 30 after 5 to 20 cycles, thereby improving the conversion efficiency of nitrate.

[0034] In one embodiment of the present application, the cathode catalytic material of the electrochemical reactor 01 is selected from any one or more of metal element catalysts corresponding to transition metals, metal oxide catalysts corresponding to transition metals, and single metal atom catalysts; and / or, the transition metals in the metal element catalysts and the metal oxide catalysts are each independently selected from any one or more of Cu, Fe, Ru, Co, and Au; and / or, the single metal atom catalyst is selected from any one or more of Cu atoms, Fe atoms, Ti atoms, Ru atoms, and V atoms.

[0035] The cathode catalytic material of the electrochemical reactor 01 is preferably within the above range, which helps to convert the nitrate solution in the first absorption solution. At the same time, the anode reaction can be selected from water oxidation reaction (OER), hydrogen oxidation reaction (HOR) and other reactions, and the catalyst used for OER can be selected from Ru metal, Ir metal, alloy and oxide catalyst, metal catalysts composed of two or three elements such as Ni, Co, Fe, oxide catalysts and hydroxide catalysts, and the catalyst used for HOR can be selected from Pt-based catalysts, such as PtAu, PtCo, PtRu and other alloys for catalysis.

[0036] In one embodiment of the present application, the system further includes a heat storage module 50 , which adopts a sensible heat storage method and / or a phase change heat storage method, and is used to provide heat to the enrichment and regeneration module 30 .

[0037] The above-mentioned heat storage module 50 is preferred and the above-mentioned heat storage method is adopted, which helps to store the waste heat dissipated by flue gas cooling and is convenient for downstream utilization, such as the separation of ammonia and the regeneration of electrolyte in the enrichment and regeneration module 30, thereby reducing energy waste and improving the economy and environmental protection of the system.

[0038] In another typical embodiment of the present application, a method for treating flue gas using the above-mentioned system is provided, the method comprising: pre-treating the flue gas and then absorbing the pre-treated flue gas with a first solution to obtain a first absorption solution containing nitrate; reducing nitrogen oxides in the first absorption solution by an electrochemical reaction to obtain a first product containing ammonia; separating the first product to obtain ammonia and a regenerated electrolyte; and blending the ammonia with a fuel to generate a combustion flue gas, wherein the flue gas includes the combustion flue gas.

[0039] In view of the fossil fuel energy / heating scenario and the demand for ammonia combustion in coal-fired power generation, the processing method of the present invention can use nitrogen oxides in flue gas as a nitrogen source to produce high-purity ammonia, and burn ammonia with ammonia, not only to establish a nitrogen cycle by electrochemical methods, but also to reduce coal consumption and carbon emissions while realizing the recycling of nitrogen oxides. Specifically, the flue gas can be purified by pretreatment, and the nitrogen oxides in the pretreated flue gas can be enriched by absorbing the flue gas with the first solution. The nitrogen oxides in the first absorption solution (the main component is nitrate solution) are converted by electrochemical reaction to realize ammonia synthesis, and the electrolyte is regenerated while obtaining ammonia. At the same time, a part of the ammonia can be directly blended with the fuel to realize the nitrogen cycle, and the other part of the ammonia can also be stored in the form of liquid ammonia for other purposes.

[0040] In one embodiment of the present application, the pretreatment also includes: removing dust from the flue gas to obtain dust-removed flue gas; subjecting the dust-removed flue gas to plasma treatment to obtain pretreated flue gas; wherein the dust removal time is 2 to 30 seconds; preferably, a mixture including water vapor and oxygen is introduced for plasma treatment, the volume ratio of the mixture to the dust-removed flue gas is 1:1 to 8, and the molar ratio of water vapor to oxygen is 1 to 20:1; and / or, the treatment time of the plasma treatment is 0.2 to 1 min; and / or, the power of the plasma treatment is 200 to 5000 W.

[0041] By removing dust from the flue gas and preferably controlling the dust removal time within the above range, it is helpful to efficiently remove dust from the flue gas. By subjecting the dust-removed flue gas to plasma treatment, introducing a mixture including water vapor and oxygen for plasma treatment, and controlling the treatment time and power of the plasma treatment within the above range, it is helpful to improve the efficiency of the plasma treatment, thereby improving the conversion rate of nitrogen oxides (including nitrogen) in the flue gas.

[0042] In one embodiment of the present application, the first solution is selected from any one or more of a strong alkaline solution, a neutral solution and a weak alkaline solution, the strong alkaline solution is selected from any one or more of a sodium hydroxide solution, a potassium hydroxide solution and a calcium hydroxide solution, the weak alkaline solution is a phosphate buffer solution and / or a hydrogen phosphate buffer solution, and the neutral solution is selected from any one or more of a sodium sulfate solution, a sodium potassium sulfate solution, a sodium nitrate solution and a potassium nitrate solution.

[0043] Preferably, the type of the first solution is within the above range, which helps to enrich the nitrogen oxides in the flue gas, thereby facilitating the subsequent electrochemical reaction. Preferably, the first solution is a combination of potassium hydroxide solution and potassium nitrate solution, and the molar ratio of the potassium hydroxide solution to the potassium nitrate solution is controlled to be 3 to 10:1, preferably 6, which helps to further improve the enrichment efficiency of the first solution.

[0044] In one embodiment of the present application, the ammonia in the first product is subjected to acid treatment and a first gas-liquid separation in sequence to obtain the first ammonia; wherein the temperature of the acid treatment is -20 to 10°C, the solution of the acid treatment is 0.1 to 3 mol / L sulfuric acid solution and / or 0.1 to 3 mol / L hydrochloric acid solution, the temperature of the first gas-liquid separation is 70 to 90°C, preferably 80°C; and / or, the liquid ammonia in the first product is subjected to a second gas-liquid separation to obtain the second ammonia, the temperature of the second gas-liquid separation is 150 to 200°C, and the pressure of the second gas-liquid separation is 1 to 5 bar; and / or, the first gas-liquid separation and the second gas-liquid separation are performed by heating.

[0045] The first product includes electrolyte and gas, and the ammonia product mainly exists in the electrolyte, and a small amount exists in the gas. The ammonia in the gas is treated with acid in the above temperature range, and the temperature of the first gas-liquid separation is controlled in the above range by using the waste heat of the upstream flue gas, which helps to improve the efficiency of the first gas-liquid separation, thereby obtaining the first ammonia. The liquid ammonia in the electrolyte is heated and expanded by using the waste heat of the upstream flue gas, thereby achieving gas-liquid separation and completing the regeneration of the electrolyte.

[0046] In one embodiment of the present application, the mass content of ammonia in the blending is 3-10%; and / or the flue gas includes nitrogen oxides, and the mass concentration of nitrogen oxides is 40-1000 mg / Nm 3 .

[0047] It is preferred to control the mass content of ammonia in the blended combustion to be within the above range, which helps to meet the demand for ammonia blended combustion in coal-fired power production and reduce coal consumption and carbon emissions.

[0048] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0049] Example 1

[0050] use Figure 1 The flue gas recirculation treatment system shown and Figure 2 The pre-treatment module shown processes the flue gas as follows: The flow rate of the flue gas is 270000Nm 3 / h, temperature is 300℃, the composition of flue gas is: NO X The concentration is 40mg / Nm 3 In terms of molar ratio, N2 accounts for 85.1%, O2 accounts for 5.9%, CO2 accounts for 1.5%, and in terms of mass ratio, the proportion of dust is less than 1%.

[0051] The flue gas is passed into the dust removal device 02 (bag filter) in the pre-treatment module 10 for dust removal for 20 seconds, and the temperature is lowered at the same time. The heat storage module 50 is used to store the residual heat for subsequent use. The dust removal flue gas outlet temperature is 80°C, and the dust ratio is 0.005% (mass ratio). The feed rate is 250000Nm 3 / h of dust-removed flue gas is introduced into the plasma treatment device 03 for plasma treatment for 30s to obtain pre-treated flue gas. The plasma is generated by rotating sliding arc discharge, and a quenching nozzle is added. The power of the plasma treatment is 1000W. The total feed amount of water vapor and oxygen in the plasma treatment is 40kg / h, and the molar ratio of water vapor to oxygen is 1:1. Then 230000Nm 3 / h of pre-treated flue gas is passed into the absorption device 04 and absorbed by the first solution to obtain a first absorption solution containing nitrates. The absorbed gas is discharged from the upper part of the absorption device 04 and further processed and discharged after passing through a drying tower. The first solution is 3 mol / L potassium hydroxide and 0.5 mol / L potassium nitrate. The feed rate of the first solution is 200 kg / h, and the pressure in the absorption device 04 is 3 bar.

[0052] The first absorption solution is introduced from the second inlet into the electrochemical reactor 01 (flowing reaction vessel b) of the electrochemical conversion module 20 to reduce the nitrogen oxides in the first absorption solution to obtain a first product containing ammonia. The cathode catalytic material of the flow-type reaction vessel is a CuCo alloy of about 25 nm, and its synthesis method is as follows: copper acetylacetonate and cobalt acetylacetonate are added to a mixed solution of oleylamine and oleic acid (the volume ratio of oleylamine and oleic acid is 4:1) in a molar ratio of 5:2, the mass concentration of copper acetylacetonate is 2g / L, and an appropriate amount of L-ascorbic acid (AA, the molar ratio of AA to copper acetylacetonate is 7:1) is added. After obtaining a yellow uniform solution through ultrasound and stirring, the reaction is closed at 140°C for 8 hours to obtain a Cu of about 25 nm. 0.8 Co 0.2 Alloy catalyst.

[0053] The anode catalyst is a commercial PtAu catalyst, and the cathode and cathode catalysts are loaded on titanium felt to make a gas diffusion electrode. The loading amount of the anode catalyst is 1 mg / cm 2 The cathode catalyst loading is 2 mg / cm 2 The positive and negative electrodes are separated by an anion exchange membrane 017 with polyaryl piperidine as the main body. The cathode side uses a cathode gas diffusion electrode 016 for gas-liquid separation, the liquid is the upstream first absorption liquid, the gas side is purged with pure N2, and the cathode outlet pressure is controlled at 2bar. The anode side uses an anode gas diffusion electrode 018 for gas-liquid separation, the reaction liquid is 3mol / L potassium hydroxide solution and 1mol / L potassium nitrate solution, hydrogen is used as the gas flow, and the anode outlet pressure is 2bar. The voltage of a single chamber is 5V.

[0054] The first product enters the enrichment and regeneration module 30 from the third inlet, and is heated (150°C, 3 bar) by using the flue gas waste heat stored in the heat storage module 50, and the solution part of the first product is purged with N2 to perform the second gas-liquid separation. The second ammonia gas after the purge is passed into the condensation system and condensed at -20°C to obtain a liquid ammonia product. The regenerated electrolyte is tested at the third outlet, and the pH of the regenerated electrolyte is adjusted to 14.3 using a potassium hydroxide solution. The gas at the cathode outlet of the electrochemical reactor 01 is acid-treated with a 1 mol / L -20°C sulfuric acid cold trap for ammonia components, and the acid trap solution is heated and purged every 10 hours (80°C, nitrogen). The first ammonia gas at the third outlet enters the ammonia utilization module 40 from the fourth inlet to condense to obtain a liquid ammonia product. The liquid ammonia product enters the blending pipeline through gasification according to production requirements, and flows back to the combustion system 60 from the fifth inlet. The ammonia gas is blended with the fuel (coal powder) at a mass ratio of 5%, and the generated combustion flue gas is returned to the pretreatment module 10.

[0055] Example 2

[0056] The difference from Example 1 is that the flue gas is passed into the dust removal device 02 (bag dust collector) in the pretreatment module 10 for dust removal for 2 seconds, and the temperature is lowered at the same time. The heat storage module 50 is used to store the residual heat for subsequent use. The dust removal flue gas outlet temperature is 75°C, and the dust ratio is 0.009% (mass ratio). The feed rate is 250000Nm 3 / h of dust-removed flue gas is introduced into the plasma treatment device 03 for plasma treatment for 0.2min to obtain pre-treated flue gas. The plasma is generated by rotating sliding arc discharge, and a quenching nozzle is added. The power of plasma treatment is 200W. The total feed amount of water vapor and oxygen in plasma treatment is 10kg / h, and the molar ratio of water vapor to oxygen is 10:1. The subsequent feed amount is 230000Nm 3 / h pre-treated flue gas is passed into the absorption device 04 and absorbed by the first solution to obtain a first absorption solution containing nitrates. The absorbed gas is discharged from the upper part of the absorption device 04 and further processed and discharged after passing through a drying tower. The first solution is 3mol / L potassium hydroxide and 0.5mol / L potassium nitrate. The feed rate of the first solution is 300kg / h, and the pressure in the absorption device 04 is 10bar.

[0057] The first absorption solution is introduced from the second inlet into the electrochemical reactor 01 (flowing reaction vessel b) of the electrochemical conversion module 20 to reduce the nitrogen oxides in the first absorption solution to obtain a first product containing ammonia. The cathode catalytic material of the flow-type reaction vessel is a CuCo alloy of about 25 nm, and its synthesis method is as follows: copper acetylacetonate and cobalt acetylacetonate are added to a mixed solution of oleylamine and oleic acid (the volume ratio of oleylamine and oleic acid is 4:1) in a molar ratio of 5:2, the mass concentration of copper acetylacetonate is 2g / L, and an appropriate amount of L-ascorbic acid (AA, the molar ratio of AA to copper acetylacetonate is 7:1) is added. After obtaining a yellow uniform solution through ultrasound and stirring, the reaction is closed at 140°C for 8 hours to obtain a Cu of about 25 nm. 0.8 Co 0.2 Alloy catalyst.

[0058] The anode catalyst is a commercial PtAu catalyst, and the cathode and cathode catalysts are loaded on titanium felt to make a gas diffusion electrode. The loading amount of the anode catalyst is 1 mg / cm 2 The cathode catalyst loading is 2 mg / cm 2The positive and negative electrodes are separated by an anion exchange membrane 017 with polyaryl piperidine as the main body. The cathode side uses a cathode gas diffusion electrode 016 for gas-liquid separation, the liquid is the upstream first absorption liquid, the gas side is purged with pure N2, and the cathode outlet pressure is controlled at 1 bar. The anode side uses an anode gas diffusion electrode 018 for gas-liquid separation, the reaction liquid is 3 mol / L potassium hydroxide solution and 1 mol / L potassium nitrate solution, hydrogen is used as the gas flow, and the anode outlet pressure is 1 bar. The voltage of a single chamber is 5V.

[0059] The first product enters the enrichment and regeneration module 30 from the third inlet, and is heated (180°C, 1 bar) by using the flue gas waste heat stored in the heat storage module 50, and the solution part of the first product is purged with air to perform the second gas-liquid separation. The second ammonia gas after the purge is passed into the condensation system and condensed at -20°C to obtain a liquid ammonia product. The regenerated electrolyte is tested at the third outlet, and the pH of the regenerated electrolyte is adjusted to 14.4 using a potassium hydroxide solution. The gas at the cathode outlet of the electrochemical reactor 01 is acid-treated with a 1 mol / L 0°C sulfuric acid cold trap for ammonia components, and the acid trap solution is heated and purged every 10 hours (70°C, nitrogen). The first ammonia gas at the third outlet enters the ammonia utilization module 40 from the fourth inlet and condenses to obtain a liquid ammonia product. The liquid ammonia product enters the blending pipeline through gasification according to production requirements, and flows back to the combustion system 60 from the fifth inlet. The ammonia gas is blended with the fuel (coal powder) at a mass ratio of 4%, and the generated combustion flue gas is returned to the pretreatment module 10.

[0060] Example 3

[0061] The difference from Example 1 is that the flue gas is passed into the dust removal device 02 (bag dust collector) in the pretreatment module 10 for dust removal for 30 seconds, and the temperature is lowered at the same time. The heat storage module 50 is used to store the residual heat for subsequent use. The dust removal flue gas outlet temperature is 85°C, and the dust ratio is 0.008% (mass ratio). The feed rate is 250000Nm 3 / h of dust-removed flue gas is introduced into the plasma treatment device 03 for plasma treatment for 1 minute to obtain pre-treated flue gas. The plasma is generated by rotating sliding arc discharge, and a quenching nozzle is added. The power of plasma treatment is 5000W. The total input flow rate of water vapor and oxygen in plasma treatment is 200kg / h, and the molar ratio of water vapor to oxygen is 20:1. The feed amount is then 230000Nm 3 / h pre-treated flue gas is passed into the absorption device 04 and absorbed by the first solution to obtain the first absorption solution containing nitrate. The absorbed gas is discharged from the upper part of the absorption device 04 and further processed and discharged after passing through the drying tower. The first solution is 3mol / L potassium hydroxide and 0.5mol / L potassium nitrate. The feed amount of the first solution is 500g / h, and the pressure in the absorption device 04 is 20bar.

[0062] The first absorption solution is introduced from the second inlet into the electrochemical reactor 01 (flowing reaction vessel b) of the electrochemical conversion module 20 to reduce the nitrogen oxides in the first absorption solution to obtain a first product containing ammonia. The cathode catalytic material of the flow-type reaction vessel is a CuCo alloy of about 25 nm, and its synthesis method is as follows: copper acetylacetonate and cobalt acetylacetonate are added to a mixed solution of oleylamine and oleic acid (the volume ratio of oleylamine and oleic acid is 4:1) in a molar ratio of 5:2, the mass concentration of copper acetylacetonate is 2g / L, and an appropriate amount of L-ascorbic acid (AA, the molar ratio of AA to copper acetylacetonate is 7:1) is added. After obtaining a yellow uniform solution through ultrasound and stirring, the reaction is closed at 140°C for 8 hours to obtain a Cu of about 25 nm. 0.8 Co 0.2 Alloy catalyst.

[0063] The anode catalyst is a commercial PtAu catalyst, and the cathode and cathode catalysts are loaded on titanium felt to make a gas diffusion electrode. The loading amount of the anode catalyst is 1 mg / cm 2 The cathode catalyst loading is 2 mg / cm 2 The positive and negative electrodes are separated by an anion exchange membrane 017 with polyaryl piperidine as the main body. The cathode side uses a cathode gas diffusion electrode 016 for gas-liquid separation, the liquid is the upstream first absorption liquid, the gas side is purged with pure N2, and the cathode outlet pressure is controlled at 3bar. The anode side uses an anode gas diffusion electrode 018 for gas-liquid separation, the reaction liquid is 3mol / L potassium hydroxide solution and 1mol / L potassium nitrate solution, hydrogen is used as the gas flow, and the anode outlet pressure is 1bar. The voltage of a single chamber is 5V.

[0064] The first product enters the enrichment and regeneration module 30 from the third inlet, and is heated (200°C, 5 bar) by using the flue gas waste heat stored in the heat storage module 50, and the solution part of the first product is purged with air to perform the second gas-liquid separation. The second ammonia gas after the purge is passed into the condensation system and condensed at -20°C to obtain a liquid ammonia product. The regenerated electrolyte is tested at the third outlet, and the pH of the regenerated electrolyte is adjusted to 14.5 using a potassium hydroxide solution. The gas at the cathode outlet of the electrochemical reactor 01 is acid-treated with a 1 mol / L 10°C sulfuric acid cold trap for ammonia components, and the acid trap solution is heated and purged every 10 hours (90°C, nitrogen). The first ammonia gas at the third outlet enters the ammonia utilization module 40 from the fourth inlet and condenses to obtain a liquid ammonia product. The liquid ammonia product enters the blending pipeline through gasification according to production requirements, and flows back to the combustion system 60 from the fifth inlet. The ammonia gas is blended with the fuel (coal powder) at a mass ratio of 3%, and the generated combustion flue gas is returned to the pretreatment module 10.

[0065] Example 4

[0066] The difference from Example 1 is that a mixture of water and oxygen is introduced for plasma treatment, and the ratio of the feed amount of the mixture to the feed amount of the flue gas after dust removal is 200:250000 kg / Nm 3 The power of plasma treatment is 200W, and finally ammonia is obtained, which is mixed with fuel to generate flue gas.

[0067] Example 5

[0068] The difference from Example 1 is that a mixture of water and oxygen is introduced for plasma treatment, and the ratio of the feed amount of the mixture to the feed amount of the flue gas after dust removal is 5:250000 kg / Nm 3 The power of plasma treatment is 150W, and ammonia is finally obtained, which is mixed with fuel to generate flue gas.

[0069] Example 6

[0070] The difference from Example 1 is that the pressure in the absorption device 04 is 20 bar; the first solution is a 3 mol / L potassium hydroxide solution, and the ratio of the feed amount of the potassium hydroxide solution to the feed amount of the pretreated flue gas is 500:230000 kg / Nm 3 , and finally ammonia is obtained, which is mixed with fuel to generate flue gas.

[0071] Example 7

[0072] The difference from Example 1 is that the pressure in the absorption device 04 is 1 bar; the first solution is a 3 mol / L potassium hydroxide solution, and the ratio of the feed amount of the potassium hydroxide solution to the feed amount of the pretreated flue gas is 150:230000 kg / Nm 3, and finally ammonia is obtained, which is mixed with fuel to generate flue gas.

[0073] Example 8

[0074] The difference from Example 1 is that the pressure on the cathode side in the flow-type reaction container is 1 bar, and the pressure on the anode side is 3 bar, and finally ammonia is obtained, which is mixed with fuel to generate flue gas.

[0075] Example 9

[0076] The difference from Example 1 is that the pressure on the cathode side in the flow-type reaction container is 0.5 bar, and the pressure on the anode side is 3 bar, and finally ammonia is obtained, which is mixed with fuel to generate flue gas.

[0077] Example 10

[0078] The difference from Example 1 is that the ammonia in the first product is subjected to acid treatment and a first gas-liquid separation in sequence to obtain a first ammonia; the temperature of the acid treatment is 10°C, the temperature of the first gas-liquid separation is 70°C, the liquid ammonia in the first product is subjected to a second gas-liquid separation to obtain a second ammonia, the temperature of the second gas-liquid separation is 200°C, the pressure of the second gas-liquid separation is 1 bar, and the obtained ammonia is mixed with fuel to generate flue gas.

[0079] Embodiment 11

[0080] The difference from Example 1 is that the ammonia in the first product is subjected to acid treatment and a first gas-liquid separation in sequence to obtain a first ammonia; the temperature of the acid treatment is 15°C, the temperature of the first gas-liquid separation is 50°C, the liquid ammonia in the first product is subjected to a second gas-liquid separation to obtain a second ammonia, the temperature of the second gas-liquid separation is 130°C, the pressure of the second gas-liquid separation is 0.5 bar, and the obtained ammonia is mixed with fuel to generate flue gas.

[0081] Test method:

[0082] Ammonia selectivity = (liquid ammonia molar amount per unit time × 96485 × 8 / power consumption of electrochemical reactor per unit time) × 100%, wherein liquid ammonia is obtained after condensation of ammonia gas, the mass of liquid ammonia is obtained by weighing the liquid ammonia storage tank, and liquid ammonia molar amount = liquid ammonia mass / ammonia molecular weight.

[0083] Nitrogen oxide conversion rate = mass of nitrogen oxides in the first product after electrochemical reduction reaction / mass of nitrogen oxides in flue gas after dust removal × 100%, wherein, Technical Specification for Continuous Monitoring of Flue Gas Emissions: HJ 75-2017; Method for Measuring the Mass of Nitrogen Oxides in Flue Gas After Dust Removal: Measured by Constant Potential Electrolysis, HJ 693-2014; Method for Measuring the Mass of Nitrogen Oxides in the First Product: Measured by Ion Chromatography, HJ 84-2016.

[0084] The results of the ammonia selectivity and nitrogen oxide conversion rate of the above examples are shown in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] in, Figure 3 is a schematic diagram of the electrochemical reactor of the present application, from Figure 3 It can be seen that the electrochemical reactor 01 includes a high-pressure reaction vessel a and a flow reaction vessel b. The high-pressure reaction vessel a includes an external power supply 011, a working electrode 012, a reference electrode 013, a counter electrode 014 and a stirring magnet 015.

[0089] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0090] The flue gas circulation treatment system of the present invention is aimed at the fossil fuel energy / heating scenario and according to the demand for ammonia combustion in coal-fired power generation. It can use nitrogen oxides in flue gas as a nitrogen source to produce high-purity ammonia, and burn ammonia with ammonia. It not only establishes a nitrogen cycle by an electrochemical method, but also reduces coal consumption and carbon emissions while realizing the recycling of nitrogen oxides. Specifically, the flue gas purification and nitrogen oxide enrichment can be achieved through the pretreatment module. The nitrogen oxides in the first absorption solution (the main component is nitrate solution) are converted by an electrochemical reactor to achieve ammonia synthesis. While obtaining ammonia through the enrichment and regeneration module, the regeneration of the electrolyte is also achieved. Through the ammonia utilization module, a part of the ammonia can directly enter the combustion system and be co-combusted with the fuel to realize the nitrogen cycle, and the other part of the ammonia can also be stored in the form of liquid ammonia for other purposes.

[0091] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A system for flue gas circulation treatment, characterized in that: The system comprises: A pretreatment module (10) having a first inlet and a first outlet, wherein the first inlet is connected to a flue gas source, and the pretreatment module (10) is used to pretreat and absorb the flue gas in sequence to obtain a first absorption solution containing nitrate; wherein the pretreated flue gas is absorbed by the first solution; An electrochemical conversion module (20) comprises an electrochemical reactor (01), wherein the electrochemical reactor (01) has a second inlet and a second outlet, wherein the second inlet is connected to the first outlet, and the electrochemical reactor (01) is used to electrochemically reduce nitrogen oxides in the first absorption solution to obtain a first product containing ammonia; an enrichment and regeneration module (30), having a third inlet and a third outlet, wherein the third inlet is connected to the second outlet, and the enrichment and regeneration module (30) is used to separate the first product to obtain ammonia gas and regenerated electrolyte; An ammonia utilization module (40) has a fourth inlet and a fourth outlet, the fourth inlet is connected to the third outlet, and the ammonia utilization module (40) is used to store the ammonia; the ammonia utilization module (40) also has an ammonia outlet; The combustion system (60) has a fifth inlet and a fifth outlet, wherein the fifth inlet is connected to the ammonia outlet, and the combustion system (60) is used to mix the ammonia with fuel for combustion; the fifth outlet is connected to the first inlet.

2. The system according to claim 1, characterized in that The pre-treatment module (10) further comprises a dust removal device (02), a plasma treatment device (03) and an absorption device (04) which are connected in sequence; The dust removal device (02) is used to remove dust from the flue gas to obtain dust-removed flue gas; and / or, the dust removal device (02) is selected from any one or more of a bag dust collector, an electrostatic precipitator, an electric bag combined dust collector, a wet dust collector, a mechanical dust collector and a cyclone dust collector; and / or, the outlet temperature of the dust removal device (02) is 75 to 85° C.; and / or, the mass proportion of dust in the dust-removed flue gas is <0.01%; The plasma treatment device (03) is used to perform plasma treatment on the dust-removed flue gas to obtain the pre-treated flue gas; and / or, the plasma in the plasma treatment device (03) is generated by any one or more of DBD discharge, microwave discharge, spark discharge, sliding arc discharge and rotary sliding arc discharge; and / or, a mixture comprising water vapor and oxygen is introduced for the plasma treatment, and the ratio of the feed amount of the mixture to the feed amount of the dust-removed flue gas is 10-200:250000 kg / Nm 3 ; The absorption device (04) is used to absorb the pretreated flue gas by using the first solution to obtain the first absorption solution; and / or, the pressure in the absorption device (04) is 3 to 20 bar, and / or, the ratio of the feed amount of the first solution to the feed amount of the pretreated flue gas is 200 to 500:230000 kg / Nm 3 .

3. The system according to claim 1 or 2, characterized in that: The electrochemical reactor (01) is a high-pressure reaction vessel and / or a flow-type reaction vessel; The high-pressure reaction vessel is a diaphragm-free reaction vessel, the pressure in the high-pressure reaction vessel is 1 to 10 bar, and H2 and N2 are introduced every 10 to 20 hours to provide the pressure; And / or, the pressure in the flow-type reaction container is 1 to 5 bar; the diaphragm of the flow-type reaction container is an anion exchange membrane and / or a bipolar membrane; and / or, the anion exchange membrane is selected from any one or more of polyaryl membranes, polyarylether membranes, polyethylene membranes, polystyrene membranes, polytetrafluoroethylene membranes and polyphenyl membranes modified with cationic groups, and / or, the source of the cationic groups is selected from any one or more of polyalkylammonium salts, imidazolium salts, pyridinium salts and piperidinium salts; and / or the polyalkylammonium salt is selected from any one or more of triethyl quaternary ammonium salts, trimethyl quaternary ammonium salts and tributyl quaternary ammonium salts; And / or, the cation exchange membrane in the bipolar membrane is a perfluorosulfonic acid resin, and the monomers forming the perfluorosulfonic acid resin are selected from any one or more of potassium perfluoro-1-octanesulfonate, potassium perfluoro-1-butanesulfonate, potassium perfluoro-1-hexanesulfonate and sodium perfluoro-1-pentanesulfonate.

4. The system according to any one of claims 1 to 3, characterized in that The cathode catalytic material of the electrochemical reactor (01) is selected from any one or more of a metal element catalyst corresponding to a transition metal, a metal oxide catalyst corresponding to a transition metal, and a single metal atom catalyst; and / or, the transition metals in the metal element catalyst and the metal oxide catalyst are each independently selected from any one or more of Cu, Fe, Ru, Co, and Au; and / or, the single metal atom catalyst is selected from any one or more of Cu atoms, Fe atoms, Ti atoms, Ru atoms, and V atoms.

5. The system according to any one of claims 1 to 4, characterized in that The system further comprises a heat storage module (50), wherein the heat storage module (50) adopts a sensible heat storage method and / or a phase change heat storage method, and the heat storage module (50) is used to provide heat to the enrichment and regeneration module (30).

6. A method for treating flue gas using the system according to any one of claims 1 to 5, characterized in that: The method comprises: After pre-treating the flue gas, the pre-treated flue gas is absorbed by a first solution to obtain a first absorption solution containing nitrate; Reducing nitrogen oxides in the first absorption solution by electrochemical reaction to obtain a first product containing ammonia; Separating the first product to obtain ammonia gas and regenerated electrolyte; The ammonia gas is mixed with fuel to generate combustion flue gas, and the flue gas includes the combustion flue gas.

7. The method according to claim 6, characterized in that The pre-processing further comprises: Dedusting the flue gas to obtain dedusted flue gas; Plasma-treating the dust-removed flue gas to obtain the pre-treated flue gas; Wherein, the residence time of the dust removal is 2 to 30 seconds; Preferably, the plasma treatment is carried out by introducing a mixture comprising water vapor and oxygen, wherein the molar ratio of the water vapor to the oxygen is 1 to 20:1; and / or the treatment time of the plasma treatment is 0.2 to 1 min; and / or the power of the plasma treatment is 200 to 5000 W.

8. The method according to claim 6 or 7, characterized in that: The first solution is selected from any one or more of a strong alkaline solution, a neutral solution and a weak alkaline solution, the strong alkaline solution is selected from any one or more of a sodium hydroxide solution, a potassium hydroxide solution and a calcium hydroxide solution, the weak alkaline solution is a phosphate buffer solution and / or a hydrogen phosphate buffer solution, and the neutral solution is selected from any one or more of a sodium sulfate solution, a sodium potassium sulfate solution, a sodium nitrate solution and a potassium nitrate solution.

9. The method according to any one of claims 6 to 8, characterized in that sequentially subjecting the ammonia gas in the first product to an acid treatment and a first gas-liquid separation to obtain a first ammonia gas; Wherein, the temperature of the acid treatment is -20 to 10°C, the solution of the acid treatment is 0.1 to 3 mol / L sulfuric acid solution and / or 0.1 to 3 mol / L hydrochloric acid solution, and the temperature of the first gas-liquid separation is 70 to 90°C; and / or, subjecting the liquid ammonia in the first product to a second gas-liquid separation to obtain a second ammonia gas, wherein the temperature of the second gas-liquid separation is 150 to 200° C., and the pressure of the second gas-liquid separation is 1 to 5 bar; And / or, the first gas-liquid separation and the second gas-liquid separation are performed by heating.

10. The method according to any one of claims 6 to 9, characterized in that The mass content of ammonia in the blending is 3-10%; and / or the flue gas includes nitrogen oxides, and the mass concentration of the nitrogen oxides is 40-1000 mg / Nm 3 .

Images