A system and method for purifying flue gas by activating free radicals using modified porous carbon

Abstract

The present invention provides a system and method for purifying flue gas by activating free radicals using modified porous carbon, wherein the modified straw biochar is activated by an advanced oxidation wet spray modification tower, and then the modified straw biochar is used to induce free radicals / active components in the flue to convert SO2 and NO in the flue gas into x 、Hg 0 and As 3+ Simultaneously oxidized to H2SO4, HNO3, Hg 2+ and As 5+ , and adsorbed on the porous carbon. The saturated porous carbon is captured by the bag filter at the end of the flue and then activated and regenerated. The desorbed products H2SO4, HNO3, Hg 2+ and As 5+ Comprehensive resource utilization can be achieved through multi-stage separation. The advanced oxidation wet spray modification tower developed by this invention can achieve multi-stage activation modification within a single reactor, while the flue heterogeneous three-phase impact reactor has extremely high enhanced mixing and mass transfer performance. Therefore, this device has outstanding comprehensive advantages such as being able to utilize the flue for improvement, simple structure, short process flow, high mass transfer efficiency, high efficiency of simultaneous pollutant removal, and green process.

Description

Technical Field

[0001] The present invention belongs to the field of air pollution control, and in particular relates to a method and system for simultaneously removing multiple pollutants from flue gas by spraying activated free radicals through advanced oxidation wet-process modified porous carbon. Background Art

[0002] Fossil fuels still dominate the global energy mix, with coal, in particular, accounting for over 50% of my country's total energy consumption. However, the coal combustion process often produces and releases a variety of atmospheric pollutants, such as sulfur dioxide, nitrogen oxides, and heavy metals like mercury and arsenic. These pollutants, when released into the atmosphere, can cause serious hazards such as acid rain, photochemical smog, and carcinogenic and teratogenic effects. Therefore, researching and developing environmentally friendly, cost-effective, and efficient flue gas desulfurization, denitrification, mercury removal, and arsenic removal technologies and processes holds significant theoretical and practical value, as well as significant social implications for achieving sustainable development of the national economy.

[0003] Domestic and foreign scientific and technological personnel and engineers have developed a variety of flue gas desulfurization, denitrification, demercurization and dearsenicization technologies and equipment. However, due to the limitations and timeliness of technological development, the existing flue gas desulfurization, denitrification, demercurization and dearsenicization technologies and processes were only targeted at removing a certain pollutant when they were first developed (for example, they could only remove one of sulfur dioxide, nitrogen oxides, heavy metal mercury or arsenic), making it difficult to achieve the simultaneous removal of multiple pollutants from the flue gas. For example, the mainstream flue gas desulfurization and denitrification technologies currently used in power plants and boilers at home and abroad are calcium-based wet flue gas desulfurization process and amino selective catalytic reduction denitrification process (i.e., SCR denitrification process). Although these two methods can achieve graded desulfurization and denitrification, neither can achieve the simultaneous removal of two pollutants in one reactor, let alone the removal of heavy metal mercury in coal-fired flue gas. Therefore, if we want to further achieve the removal of mercury and arsenic in coal-fired flue gas, we must further install coal-fired flue gas demercurization and dearsenicization equipment on this basis. However, although the combined use of the three processes can achieve the simultaneous desulfurization, denitrification, demercurization and dearsenicization of flue gas, it will also make the entire removal system appear large and complex, occupy a huge area, and lead to high initial investment and operating costs of the system. There are currently more than 500,000 small and medium-sized coal-fired boilers, industrial kilns and waste incinerators in my country's industrial and civilian sectors. If corporate users of these small and medium-sized combustion facilities install SO2, NO x The equipment and processes for removing three pollutants, mercury and arsenic, will face extremely huge economic pressure and consume enormous energy, which is not conducive to the large-scale promotion and implementation of relevant removal technologies and policies.

[0004] In summary, if SO2, NO xThe simultaneous removal of sulfur, mercury and arsenic, that is, the simultaneous desulfurization, denitrification, demercurization and dearsenicization, is expected to greatly reduce the complexity and operating costs of the system and has good market application prospects. At present, the technologies for the simultaneous desulfurization, denitrification, demercurization and dearsenicization of flue gas have been developed, mainly including catalysis, adsorption, plasma removal, complex absorption, traditional oxidation and free radical advanced oxidation. The plasma method has the disadvantages of poor reliability and high operating energy consumption. The adsorption method has the disadvantages of low removal efficiency (especially the removal efficiency of the key component NO is very low) and the need for intermittent operation of the reactor. The complexation method (using complex iron and cobalt ammonia solution for absorption) has the disadvantages of large complexing agent regeneration loss and high regeneration energy consumption. The traditional oxidation method has the problems of high reagent prices (such as sodium chlorite and potassium permanganate), low oxidizing ability (such as hydrogen peroxide and persulfate), large oxidant consumption (easy to self-decompose), secondary pollution (for example, the products of potassium permanganate and chlorite are difficult to handle). The currently widely-watched free radical advanced oxidation technology has achieved great development, but there are still technical and economic difficulties such as large investment and high operating costs, and poor technological maturity. Therefore, these technologies are still a long way from industrial application, and scientific and technological personnel in this field still need to invest more research and efforts.

[0005] Among various common simultaneous removal technologies, free radical advanced oxidation (FRAO) offers comprehensive advantages, including strong oxidation capacity and a green and environmentally friendly process. It is a promising technology and process for the simultaneous removal of multiple pollutants from flue gas. However, the development of existing FRAO FRAO technologies and processes has been relatively slow. Key challenges can be summarized as follows: (I) Using separate electrochemical, photochemical, and microwave activation technologies suffers from low energy efficiency and activation efficiency (generally requiring the use of other catalysts or activators); (II) Thermal activation technologies face challenges such as low free radical activation efficiency and low pollutant removal efficiency; (III) Transition metal ion activation technologies face challenges such as difficulty separating and recovering transition metal ions and secondary pollution; and (IV) Transition metal oxide activation technologies face challenges such as the susceptibility of metal oxides to decomposition and deactivation in acidic solutions. These four key issues are the major bottlenecks or obstacles hindering the large-scale industrial application of FRAO FRAO for simultaneous desulfurization, denitrification, mercury removal, and arsenic removal. Furthermore, extensive scientific research and industrial practice have confirmed that the primary rate-determining step in gas-liquid-solid three-phase reactions is mass transfer. Therefore, the use of traditional reactors for simultaneous desulfurization, denitrification, demercurization and dearsenicization can easily lead to shortcomings such as large reactor size and high operating energy consumption. Further research and development of high-efficiency multiphase reactors that can achieve good mixing efficiency and enhance mass transfer rate is needed. Summary of the Invention

[0006] In response to the above series of technical difficulties and bottlenecks, the present invention provides a system and method for purifying flue gas by activating free radicals using modified porous carbon, which belongs to the field of atmospheric pollutant control. In the present invention, the modified straw biochar is first activated by an advanced oxidation wet spray modification tower, and then the modified straw biochar is used to induce free radicals / active components in the flue to convert SO2 and NO in the flue gas into x 、Hg 0 and As 3+ Simultaneously oxidized to H2SO4, HNO3, Hg 2+ and As 5+ , and adsorbed on the porous carbon. The saturated porous carbon is captured by the bag filter at the end of the flue and then activated and regenerated. The products after desorption are H2SO4, HNO3, Hg 2+ and As 5+ Comprehensive resource utilization can be achieved through multi-stage separation, and there is no secondary pollution in the removal process.

[0007] The basic principles of the method and system described in the present invention are:

[0008] (1) Straw biochar modification process: First, microwaves are used to activate a mixed solution of persulfate, ammonia, and sodium sulfide in conjunction with flue gas waste heat to generate free radicals / active components to activate and modify the biochar. The purpose is to expand the pores of the biochar and generate abundant oxygen-, nitrogen-, and sulfur-containing functional groups on its surface. The above activation and modification process can be expressed by the following equation (1):

[0009]

[0010] (2) The process of persulfate activation by modified porous carbon to generate free radicals and active components: persulfate (S2O8 2- ) produces highly oxidizing free radicals / active species (such as SO4 - OH, HO2, O and O2 1 ), the specific process can be expressed by the following chemical equation (2):

[0011]

[0012] (3) Simultaneous removal of pollutants: using highly oxidizing free radicals / active components (such as SO4 - OH, HO2, O and O2 1 ) Simultaneously oxidize and remove SO2 and NO from flue gas x 、Hg 0 and As 3+ , SO2, NO x 、Hg 0 and As3+ Oxidized to H2SO4, HNO3, Hg 2+ and As 5+ , thus achieving efficient removal of multiple pollutants from flue gas at the same time. The specific process can be represented by the following chemical reactions (3)-(6):

[0013] SO4 - ·+·OH+·O+O2 1 +HO2·+SO2+H2O→H2SO4 (3)

[0015] SO4 - ·+·OH+O2 1 +·O+HO2·+NO x +H2O→HNO3 (4)

[0017] SO4 - ·+·OH+·O+O2 1 +HO2·+Hg 0 +H2O→Hg 2+ (5)

[0019] SO4 - ·+·OH+·O+O2 1 +HO2·+As 3+ +H2O→As 5+ (6)

[0021] After the reaction, the porous carbon that loses its activity is returned to the advanced oxidation wet spray modification tower (2) and is regenerated through the activation modification process as shown in equation (1), so that it regains new activation free radical ability, thereby realizing the recycling of the activator. 2+ and As 5+ The comprehensive resource utilization of the reaction products can be achieved through the multi-level comprehensive resource utilization system at the tail.

[0022] Utilizing the above principles, the present invention provides a system for purifying flue gas by activating free radicals using modified porous carbon. The system comprises an advanced oxidation wet spray modification tower 2 for modifying straw biochar and a flue heterogeneous three-phase impact reactor 14 for inducing free radicals / active components for simultaneous oxidation desulfurization, denitrification and demercurization.

[0023] A plurality of modified solution atomizing impingement nozzles 4 are provided on the inner sidewall of the advanced oxidation wet spray modification tower 2, and the modified solution atomizing impingement nozzles 4 on both sides are arranged horizontally opposite each other. A modified solution and porous carbon mixture 3 is provided at the lower portion of the advanced oxidation wet spray modification tower 2, and a superconducting heat pipe 5 and a first microwave emitter 6 are arranged in sequence at the upper portion. The lower portion of the advanced oxidation wet spray modification tower 2 is connected to a liquid-solid material mixing device 1, and its top is connected to a liquid-solid separation device 10. The lower portion of the advanced oxidation wet spray modification tower 2 is provided with an advanced oxidation wet spray modification tower total inlet c, a circulating solution left outlet e, a circulating solution right outlet f, and a total outlet g for the modified liquid-solid mixture.

[0024] The flue heterogeneous three-phase impact reactor 14 is equipped with a modified porous carbon nozzle 15, a peroxide nozzle 16, a quartz protection device 17, an ultraviolet lamp 18, and a bag filter 19. The flue heterogeneous three-phase impact reactor 14 is connected to the flue gas waste heat heater 11 and the liquid-solid material mixing device 1 via pipelines. The peroxide nozzle 16 is connected to the peroxide solution device 20 via pipelines.

[0025] Furthermore, the effective height H1 of the advanced oxidation wet spray modification tower 2 is between 150 cm and 400 cm. The modified solution atomizing nozzles 4, superconducting heat pipes 5, and first microwave emitters 6 on either side of the reactor are arranged in a sequential arrangement with equal vertical and horizontal spacing. The modified solution atomizing nozzles 4, superconducting heat pipes 5, and first microwave emitters 6 are spaced apart in a vertical sequence, with an optimized spacing M1 between 20 cm and 80 cm. The optimized distance L1 between the nozzles on either side of the reactor is between 60 cm and 400 cm. The initial velocity of the modified solution atomizing nozzles 4 is between 20.0 m / s and 100 m / s to ensure sufficient medium mixing efficiency and mass transfer rate.

[0026] Furthermore, the inner wall of the flue heterogeneous three-phase impact reactor 14 is equipped with multiple modified porous carbon nozzles 15 and peroxide nozzles 16, spaced apart from each other in a sequential arrangement, with the same longitudinal and transverse spacing M2. The initial velocity of the modified porous carbon nozzles 15 is between 15.0 m / s and 60 m / s to ensure sufficient medium mixing efficiency and mass transfer rate. The optimized distance L2 between the nozzles on both sides of the flue is between 120 cm and 600 cm, and the optimized spacing M3 between the second microwave emitters 18 is between 20 cm and 60 cm.

[0027] Furthermore, the liquid-solid material mixing device 1 is provided with a modified solution inlet a of the liquid-solid material mixing device, a biochar inlet b of the liquid-solid material mixing device and a deactivated biochar re-inlet d of the liquid-solid material mixing device. The liquid-solid material mixing device 1 is connected to the total inlet c of the advanced oxidation wet spray modification tower, and the deactivated biochar re-inlet d of the liquid-solid material mixing device is connected to the flue heterogeneous three-phase impact reactor 14 through a pipeline.

[0028] Furthermore, a first solution pump 7 is provided on the pipeline of the left outlet e of the circulating solution of the advanced oxidation wet spray modification tower 2, a second solution pump 8 is provided on the pipeline of the right outlet f of the circulating solution, a third solution 9 is provided on the pipeline of the total outlet g of the modified liquid-solid mixture and the total inlet h of the liquid-solid rapid separator mixture; a first fan 12 is provided on the connecting pipeline between the flue gas waste heat heater 11 and the flue heterogeneous three-phase impact reactor 14.

[0029] Furthermore, a bag filter 19 is provided at the end of the flue heterogeneous three-phase impact reactor 14, and the bag filter outlet n is connected to the product desorption and washing system 21 and the product separation system 22 in sequence. The product separation system 22 is connected to the inlet d of the deactivated biochar of the liquid-solid material mixing device, and the deactivated biochar in the flue heterogeneous three-phase impact reactor 14 is recycled.

[0030] Furthermore, the effective height H1 of the advanced oxidation wet spray modification tower 2 is between 150 cm and 400 cm. The modified solution atomizing nozzles 4, superconducting heat pipes 5, and first microwave emitters 6 on either side of the reactor are arranged in a sequential arrangement with equal vertical and horizontal spacing. The modified solution atomizing nozzles 4, superconducting heat pipes 5, and first microwave emitters 6 are spaced apart in a vertical sequence, with an optimized spacing M1 between 20 cm and 80 cm. The optimized distance L1 between the nozzles on either side of the reactor is between 60 cm and 400 cm. The initial velocity of the modified solution atomizing nozzles 4 is between 20.0 m / s and 100 m / s to ensure sufficient medium mixing efficiency and mass transfer rate.

[0031] Furthermore, the inner wall of the flue heterogeneous three-phase impact reactor 14 is equipped with multiple modified porous carbon nozzles 15 and peroxide nozzles 16, spaced apart from each other in a sequential arrangement, with the same longitudinal and transverse spacing M2. The initial velocity of the modified porous carbon nozzles 15 is between 15.0 m / s and 60 m / s to ensure sufficient medium mixing efficiency and mass transfer rate. The optimized distance L2 between the nozzles on both sides of the flue is between 120 cm and 600 cm, and the optimized spacing M3 between the second microwave emitters 18 is between 20 cm and 60 cm.

[0032] Furthermore, the liquid-solid material mixing device 1 is provided with a modified solution inlet a of the liquid-solid material mixing device, a biochar inlet b of the liquid-solid material mixing device and a deactivated biochar re-inlet d of the liquid-solid material mixing device. The liquid-solid material mixing device 1 is connected to the total inlet c of the advanced oxidation wet spray modification tower, and the deactivated biochar re-inlet d of the liquid-solid material mixing device is connected to the flue heterogeneous three-phase impact reactor 14 through a pipeline.

[0033] Furthermore, a first solution pump 7 is provided on the pipeline of the left outlet e of the circulating solution of the advanced oxidation wet spray modification tower 2, a second solution pump 8 is provided on the pipeline of the right outlet f of the circulating solution, a third solution 9 is provided on the pipeline of the total outlet g of the modified liquid-solid mixture and the total inlet h of the liquid-solid rapid separator mixture; a first fan 12 is provided on the connecting pipeline between the flue gas waste heat heater 11 and the flue heterogeneous three-phase impact reactor 14.

[0034] Furthermore, a bag filter 19 is provided at the end of the flue heterogeneous three-phase impact reactor 14, and the bag filter outlet n is connected to the product desorption and washing system 21 and the product separation system 22 in sequence. The product separation system 22 is connected to the inlet d of the deactivated biochar of the liquid-solid material mixing device, and the deactivated biochar in the flue heterogeneous three-phase impact reactor 14 is recycled.

[0035] The present invention also discloses a method for purifying flue gas by activating free radicals using modified porous carbon. The operation process of the biochar modification and pollutant removal system is as follows:

[0036] I. The modified solution enters the liquid-solid mixing device 1 through the modified solution inlet a, and the straw biochar enters the liquid-solid mixing device 1 through the biochar inlet b. After being evenly mixed in the liquid-solid mixing device 1, the straw biochar and modified solution enter the bottom of the advanced oxidation wet spray modification tower 2 through the main inlet c of the advanced oxidation wet spray modification tower. The first solution pump 7 and the second solution pump 8 are simultaneously activated to pump the liquid-solid mixture through the modified solution atomizing nozzles 4 on both sides, spraying it horizontally into the modification zone to activate and modify the biochar. Simultaneously, the superconducting heat pipe 5 and the first microwave emitter 6 are simultaneously activated to radiate flue gas waste heat and microwaves to activate the modified solution and generate highly reactive free radicals / active components. These highly reactive free radicals / active components simultaneously activate and modify the straw biochar, ultimately producing a modified porous carbon with a well-developed pore structure and abundant surface functional groups.

[0037] II. The modified porous carbon modified within the advanced oxidation wet spray modification tower 2 is pumped from the total outlet g of the modified liquid-solid mixture by a circulation pump 9 into a liquid-solid separation device 10 for liquid-solid separation. The separated modified porous carbon enters a flue gas waste heat heater 11 for drying using the flue gas waste heat. It is then fed by a first blower 12 into a flue heterogeneous three-phase impact reactor 14 for free radical activation and oxidative adsorption removal of pollutants. The separated waste solution is then fed back into the advanced oxidation wet spray modification tower 2 through the liquid-solid rapid separator solution outlet i for reuse, avoiding the generation of secondary wastewater and conserving water resources. Within the advanced oxidation wet spray modification tower 2, a superconducting heat pipe 5 utilizes the flue gas waste heat to rapidly heat the material, while microwaves emitted by a first microwave emitter 6 rapidly expand the pores of the biochar. The two can also synergistically activate the modified solution to induce highly active free radicals / active components to modify the porous carbon, and produce highly active functional groups on its surface, which are then used to further activate peroxides to generate free radicals for oxidative removal of pollutants, thereby achieving the multi-faceted synergistic effects of biochar pore expansion, surface functional group generation, free radical activation, and multiphase mass transfer enhancement.

[0038] III. Flue gas from a coal-fired boiler enters the reaction zone of the flue heterogeneous three-phase impact reactor. The modified porous carbon nozzle 15 and the peroxide nozzle 16 spray the modified porous carbon and the peroxide solution into the reaction zone, respectively. At the same time, the second microwave emitter 18 is turned on to cooperate with the modified porous carbon to activate the free radicals / active components (SO4 - OH, HO2, O and O2 1 ) and SO2 and NO in flue gas x 、Hg 0 and As 3+ Simultaneous oxidation and removal reaction occurs, and SO2 and NO x 、Hg 0 and As 3+ Oxidized to H2SO4, HNO3, Hg 2+ and As 5+ , thereby achieving the simultaneous removal of multiple pollutants from the flue gas. After use, the deactivated porous carbon is captured by the bag filter 19 at the rear. The deactivated biochar is then fed by the second fan 13 through the liquid-solid material mixing device and then into the advanced oxidation wet spray modification tower 2 at inlet d for further modification, enabling repeated reuse.

[0039] IV. The adsorption saturated porous carbon can be desorbed and separated from the adsorbed products on the porous carbon by high temperature desorption and hot water washing in the product desorption and washing system 21. The products after desorption (H2SO4, HNO3, Hg 2+ and As 5+) enters the product separation system 22 for multi-stage comprehensive resource utilization. The multi-stage comprehensive resource utilization system includes a mercury / arsenic separation device, an ammonia neutralization acid device, and a flue gas waste heat evaporation crystallization fertilizer preparation device. In the mercury / arsenic separation device, Hg 2+ and As 5+ Mercury sulfide and arsenic sulfide can be produced by adding divalent sulfide ions to react and then precipitate, which can be separated and recovered. In the ammonia neutralization acid device, H2SO4 and HNO3 can be reacted with ammonia to produce ammonium sulfate and ammonium nitrate. In the flue gas waste heat evaporation crystallization fertilizer preparation device, agricultural fertilizer is prepared after evaporation crystallization by boiler flue gas waste heat. Therefore, the entire removal process not only has no secondary pollution, but also can obtain important resources such as mercury / arsenic and agricultural fertilizer, which has good development and application prospects.

[0040] Furthermore, the microwave radiation power density in the advanced oxidation wet spray modification tower 2 needs to be maintained at 300W / m 3 ~2000W / m 3 The thermal radiation power of the superconducting heat pipe must be maintained at 600W / m 3 ~5000W / m 3 The microwave radiation power in the flue heterogeneous three-phase impact reactor 14 must be maintained at 200W / m 3 ~1500W / m 3 between.

[0041] Furthermore, the modification solution used in the advanced oxidation wet spray modification tower 2 is composed of a mixture of persulfate, ammonia water, and sodium sulfide. The molar concentration of the persulfate should be maintained between 0.05 mol / L and 2.0 mol / L, the molar concentration of the ammonia water should be maintained between 0.02 mol / L and 1.0 mol / L, and the molar concentration of the sodium sulfide should be maintained between 0.05 mol / L and 2.0 mol / L.

[0042] Furthermore, the optimized pH value range of the modified solution in the advanced oxidation wet spray modification tower (2) is 0.05-6.5, the optimized reaction temperature is 50° C.-100° C., and the optimized modified porous carbon dosage is 80 mg / L-400 mg / L.

[0043] Furthermore, the peroxide solution in the flue heterogeneous three-phase impact reactor 14 is mainly composed of H2O2 and persulfate. The molar concentration of persulfate needs to be maintained between 0.1mol / L and 2.5mol / L, and the molar concentration of H2O2 needs to be maintained between 0.2mol / L and 1.5mol / L. The optimized pH value range of the peroxide solution is 0.08 to 6.0. The mass ratio of the modified biochar and the peroxide solution injected into the flue heterogeneous three-phase impact reactor (14) is 5wt.% to 25wt.%.

[0044] Furthermore, flue gas pollutants SO2 and NO x Hg 0 and As2O3(As 3+ ) were 100-8000ppm, 100-2500ppm, and 20μg / m 3 ~1200 μg / m 3 and 30 μg / m 3 ~2000 μg / m 3 The optimized particle size of the modified porous carbon is 0.003 μm to 0.5 μm.

[0045] Furthermore, when the flue gas waste heat heater 11 utilizes the flue gas waste heat to dry the modified porous carbon, the operating temperature inside the flue gas waste heat heater 11 is not lower than 160° C., and the moisture content of the modified porous carbon after drying is not higher than 10%.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) Existing technologies for removing multiple pollutants from flue gas by free radical advanced oxidation generally have various deficiencies. For example, high-energy free radical activation removal technologies such as electrochemistry, ultraviolet light, microwave and ultrasound have deficiencies such as low energy utilization efficiency and low free radical activation efficiency. Thermal activation removal technology has problems such as low free radical yield and low pollutant removal efficiency. Transition metal ion activation removal technology has problems such as difficulty in recovering metal ions and secondary pollution. Transition metal oxide activation removal technology has the advantages of simple process and low equipment requirements, and metal oxide catalysts can be recycled and reused. However, common transition metal oxide catalysts mainly include iron oxide, copper oxide, manganese oxide, cobalt oxide and cerium oxide as well as the above-mentioned mixed metal oxides, but these transition metal oxides are all alkaline oxides and are easily corroded and decomposed in acidic solutions (the oxidation removal products of this process are sulfuric acid and nitric acid), and then poisoned and inactivated, resulting in high application costs. The present invention proposes to use straw porous carbon to replace traditional transition metal oxides to activate free radicals to remove flue gas pollutants, which can effectively overcome the shortcomings of metal oxides such as easy decomposition and deactivation in acidic solutions and metal ion leakage. At the same time, it also has the advantages of a wide source of straw biochar raw materials and easy treatment of deactivated catalysts, and has good technical and economic advantages.

[0048] (2) Existing activator modification technologies and processes usually have complex modification processes and equipment, resulting in long process flows and complex equipment, which in turn leads to huge initial investment and operating costs. Therefore, the development of energy-saving and low-carbon modification technologies and processes with low energy consumption, low cost and short process flows is an important research topic and development direction in this field. The advanced oxidation wet spray modification tower developed in the present invention can achieve one-step activation modification in one reactor to produce three highly active functional groups, and can simultaneously achieve efficient pore expansion of the adsorbent. It has outstanding advantages such as simple modification equipment and short process flows, and has good industrial prospects.

[0049] (3) Solid catalyst activation persulfate induced free radical oxidation to remove SO2 and NO in flue gas x 、Hg 0 and As 3+ It is a three-phase reaction process of gas, liquid and solid. In complex heterogeneous reaction processes, the oxidation rate of free radicals is often extremely fast, so the multiphase mass transfer process is usually the rate-controlling step of the entire removal process. How to simply and efficiently enhance the mass transfer process is the key to achieving efficient removal of pollutants. However, the mass transfer efficiency of the bubbling bed reactor and spray tower reactor commonly used in this field is relatively low and cannot meet the requirements of industrial applications. The flue heterogeneous three-phase impact reactor developed by the present invention has extremely high enhanced mixing and mass transfer performance, which can greatly promote the heterogeneous removal process, thereby achieving higher pollutant removal efficiency (the removal efficiency of the four pollutants can reach 100%).

[0050] In summary, the modification and removal system developed in the present invention has outstanding comprehensive advantages such as simple and compact structure, short process flow, high mass transfer efficiency, high simultaneous pollutant removal efficiency and green and environmentally friendly process. It is a new flue gas purification method and system with broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 .Schematic diagram of the system for simultaneously removing multiple pollutants from flue gas by activating free radicals using advanced oxidation wet spray modified porous carbon.

[0052] Figure 2 . Schematic diagram of the layout and dimensions of the microwave emitter, superconducting heat pipe and nozzle in the advanced oxidation wet spray modification tower.

[0053] Figure 3 .Schematic diagram of the arrangement and dimensions of the modified porous carbon nozzle, peroxide nozzle and flue wall in the flue heterogeneous three-phase impact reactor.

[0054] Figure 4 .Schematic diagram of the arrangement and dimensions of the microwave emitters in the flue heterogeneous three-phase impact reactor.

[0055] Reference numerals: Liquid-solid material mixing device 2. Advanced oxidation wet spray modification tower 2-1. Side wall of advanced oxidation wet spray modification tower 3. Modified solution and porous carbon mixture 4. Modified solution atomization impact nozzle 5. Superconducting heat pipe 6. First microwave launcher 7. First solution pump 8. Second solution pump 9. Third solution pump 10. Liquid-solid separation device 11. Flue gas waste heat heater 12. First fan 13. Second fan 14. Flue heterogeneous three-phase impact reactor 14-1. Flue wall 15. Modified porous carbon nozzle 16. Peroxide nozzle 17. Quartz protection device 18. Microwave launcher 19. Bag filter 20. Peroxide Solution Device 21. Product Desorption and Washing System 22. Product Separation System a. Liquid-Solid Material Mixing Device Modified Solution Inlet b. Liquid-Solid Material Mixing Device Biochar Inlet c. Advanced Oxidation Wet Spray Modification Tower Main Inlet d. Liquid-Solid Material Mixing Device Deactivated Biochar Re-inlet e. Circulating Solution Left Outlet f. Circulating Solution Right Outlet g. Modified Liquid-Solid Mixture Main Outlet h. Liquid-Solid Rapid Separator Mixture Main Inlet i. Liquid-Solid Rapid Separator Solution Discharge Port j. Liquid-Solid Rapid Separator Modified Biochar Outlet k. Liquid-Solid Rapid Separator Explosion Vent m. Flue Gas Waste Heat Heater Outlet n. Bag Filter Outlet DETAILED DESCRIPTION

[0056] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0057] like Figure 1 As shown, a system for purifying flue gas by activating free radicals using modified porous carbon includes an advanced oxidation wet spray modification tower 2 for straw biochar modification and a flue heterogeneous three-phase impact reactor 14 for inducing free radicals / active components for simultaneous oxidation desulfurization, denitrification and demercurization.

[0058] Multiple modified solution atomizing nozzles 4 are provided on the inner sidewalls of the advanced oxidation wet spray modification tower 2, and the modified solution atomizing nozzles 4 on both sides are arranged horizontally opposite each other. A modified solution and porous carbon mixture 3 is provided at the lower portion of the advanced oxidation wet spray modification tower (2), and a superconducting heat pipe 5 and a first microwave emitter 6 are arranged in sequence at the upper portion. The lower portion of the advanced oxidation wet spray modification tower 2 is connected to the liquid-solid material mixing device 1, and its top is connected to the liquid-solid separation device 10. The lower portion of the advanced oxidation wet spray modification tower 2 is provided with the advanced oxidation wet spray modification tower main inlet c, the circulating solution left outlet e, the circulating solution right outlet f, and the total outlet g for the modified liquid-solid mixture.

[0059] The flue heterogeneous three-phase impact reactor 14 is equipped with a modified porous carbon nozzle 15, a peroxide nozzle 16, a quartz protection device 17, an ultraviolet lamp 18, and a bag filter 19. The flue heterogeneous three-phase impact reactor 14 is connected to the flue gas waste heat heater 11 and the liquid-solid material mixing device 1 via pipelines. The peroxide nozzle 16 is connected to the peroxide solution device 20 via pipelines.

[0060] Combine Figure 1 and Figure 2 The effective height H1 of the advanced oxidation wet spray modification tower 2 is between 150cm and 400cm. The modified solution atomizing impingement nozzles 4, superconducting heat pipes 5, and first microwave emitters 6 on both sides of the reactor are arranged in a sequential manner with equal longitudinal and lateral spacing. The modified solution atomizing impingement nozzles 4, superconducting heat pipes 5, and first microwave emitters 6 are arranged in a vertically spaced sequence, with an optimized spacing M1 between 20cm and 80cm. The optimized distance L1 between the nozzles on both sides of the reactor is between 60cm and 400cm. The initial velocity of the modified solution atomizing impingement nozzles 4 is between 20.0m / s and 100m / s to ensure sufficient medium mixing efficiency and mass transfer rate.

[0061] Combine Figure 1 、 Figure 3 and Figure 4 The inner wall of the flue heterogeneous three-phase impact reactor 14 is equipped with multiple modified porous carbon nozzles 15 and peroxide nozzles 16, which are spaced apart from each other in a sequential arrangement, with the same longitudinal and transverse spacing M2. The initial velocity of the modified porous carbon nozzles 15 is between 15.0 m / s and 60 m / s to ensure sufficient medium mixing efficiency and mass transfer rate. The optimized distance L2 between the nozzles on both sides of the flue is between 120 cm and 600 cm. The optimized spacing M3 between the second microwave emitters 18 is between 20 cm and 60 cm. The second microwave emitters 18 are equipped with quartz protection devices 17.

[0062] like Figure 1 As shown, the liquid-solid material mixing device 1 is provided with a modified solution inlet a of the liquid-solid material mixing device, a biochar inlet b of the liquid-solid material mixing device, and a deactivated biochar re-inlet d of the liquid-solid material mixing device. The liquid-solid material mixing device 1 is connected to the total inlet c of the advanced oxidation wet spray modification tower, and the deactivated biochar re-inlet d of the liquid-solid material mixing device is connected to the flue heterogeneous three-phase impact reactor 14 through a pipeline.

[0063] A first solution pump 7 is provided on the pipeline of the left outlet e of the circulating solution of the advanced oxidation wet spray modification tower 2, a second solution pump 8 is provided on the pipeline of the right outlet f of the circulating solution, a third solution 9 is provided on the pipeline of the total outlet g of the modified liquid-solid mixture and the total inlet h of the liquid-solid rapid separator mixture; a first fan 12 is provided on the connecting pipeline between the flue gas waste heat heater 11 and the flue heterogeneous three-phase impact reactor 14.

[0064] A bag filter 19 is provided at the end of the flue heterogeneous three-phase impact reactor 14. The bag filter outlet n is connected to the product desorption and washing system 21 and the product separation system 22 in sequence. The product separation system 22 is connected to the inlet d of the deactivated biochar of the liquid-solid material mixing device. The deactivated biochar in the flue heterogeneous three-phase impact reactor 14 is recycled.

[0065] Based on a method for a system that uses modified porous carbon to activate free radicals to purify flue gas, the operating process of the biochar modification and pollutant removal system is as follows:

[0066] I. The modified solution enters the liquid-solid mixing device 1 through the modified solution inlet a, and the straw biochar enters the liquid-solid mixing device 1 through the biochar inlet b. After being evenly mixed in the liquid-solid mixing device 1, the straw biochar and modified solution enter the bottom of the advanced oxidation wet spray modification tower 2 through the main inlet c of the advanced oxidation wet spray modification tower. The first solution pump 7 and the second solution pump 8 are simultaneously activated to pump the liquid-solid mixture through the modified solution atomizing nozzles 4 on both sides, spraying it horizontally into the modification zone to activate and modify the biochar. Simultaneously, the superconducting heat pipe 5 and the first microwave emitter 6 are simultaneously activated to radiate flue gas waste heat and microwaves to activate the modified solution and generate highly reactive free radicals / active components. These highly reactive free radicals / active components simultaneously activate and modify the straw biochar, ultimately producing a modified porous carbon with a well-developed pore structure and abundant surface functional groups.

[0067] II. The modified porous carbon modified within the advanced oxidation wet spray modification tower 2 is pumped from the total outlet g of the modified liquid-solid mixture by a circulation pump 9 into a liquid-solid separation device 10 for liquid-solid separation. The separated modified porous carbon enters a flue gas waste heat heater 11 for drying using the flue gas waste heat. It is then fed by a first blower 12 into a flue heterogeneous three-phase impact reactor 14 for free radical activation and oxidative adsorption removal of pollutants. The separated waste solution is then fed back into the advanced oxidation wet spray modification tower 2 through the liquid-solid rapid separator solution outlet i for reuse, avoiding the generation of secondary wastewater and conserving water resources. Within the advanced oxidation wet spray modification tower 2, a superconducting heat pipe 5 utilizes the flue gas waste heat to rapidly heat the material, while microwaves emitted by a first microwave emitter 6 rapidly expand the pores of the biochar. The two can also synergistically activate the modified solution to induce highly active free radicals / active components to modify the porous carbon, and produce highly active functional groups on its surface, which are then used to further activate peroxides to generate free radicals for oxidative removal of pollutants, thereby achieving the multi-faceted synergistic effects of biochar pore expansion, surface functional group generation, free radical activation, and multiphase mass transfer enhancement.

[0068] III. Flue gas from a coal-fired boiler enters the reaction zone of the flue heterogeneous three-phase impact reactor. The modified porous carbon nozzle 15 and the peroxide nozzle 16 spray the modified porous carbon and the peroxide solution into the reaction zone, respectively. At the same time, the second microwave emitter 18 is turned on to cooperate with the modified porous carbon to activate the free radicals / active components (SO4 - OH, HO2, O and O2 1 ) and SO2 and NO in flue gas x 、Hg 0 and As 3+ Simultaneous oxidation and removal reaction occurs, and SO2, NO x 、Hg 0 and As 3+ Oxidized to H2SO4, HNO3, Hg 2+ and As 5+ , thereby achieving the simultaneous removal of multiple pollutants from the flue gas. After use, the deactivated porous carbon is captured by the bag filter 19 at the rear. The deactivated biochar is then fed by the second fan 13 through the liquid-solid material mixing device and then into the advanced oxidation wet spray modification tower 2 at inlet d for further modification, enabling repeated reuse.

[0069] IV. The adsorption saturated porous carbon can be desorbed and separated from the adsorbed products on the porous carbon by high temperature desorption and hot water washing in the product desorption and washing system 21. The products after desorption (H2SO4, HNO3, Hg 2+ and As 5+) enters the product separation system 22 for multi-stage comprehensive resource utilization. The multi-stage comprehensive resource utilization system includes a mercury / arsenic separation device, an ammonia neutralization acid device, and a flue gas waste heat evaporation crystallization fertilizer preparation device. In the mercury / arsenic separation device, Hg 2+ and As 5+ Mercury sulfide and arsenic sulfide can be produced by adding divalent sulfide ions to react and then precipitate, which can be separated and recovered. In the ammonia neutralization acid device, H2SO4 and HNO3 can be reacted with ammonia to produce ammonium sulfate and ammonium nitrate. In the flue gas waste heat evaporation crystallization fertilizer preparation device, agricultural fertilizer is prepared after evaporation crystallization by boiler flue gas waste heat. Therefore, the entire removal process not only has no secondary pollution, but also can obtain important resources such as mercury / arsenic and agricultural fertilizer, which has good development and application prospects.

[0070] The microwave radiation power density in the advanced oxidation wet spray modification tower 2 needs to be maintained at 300W / m 3 ~2000W / m 3 The thermal radiation power of the superconducting heat pipe must be maintained at 600W / m 3 ~5000W / m 3 The microwave radiation power in the flue heterogeneous three-phase impact reactor 14 must be maintained at 200W / m 3 ~1500W / m 3 between.

[0071] The modification solution used in the advanced oxidation wet spray modification tower 2 consists of a mixture of persulfate, ammonia, and sodium sulfide. The molar concentration of the persulfate must be maintained between 0.05 mol / L and 2.0 mol / L, the molar concentration of the ammonia must be maintained between 0.02 mol / L and 1.0 mol / L, and the molar concentration of the sodium sulfide must be maintained between 0.05 mol / L and 2.0 mol / L.

[0072] The optimized pH value range of the modified solution in the advanced oxidation wet spray modification tower (2) is 0.05-6.5, the optimized reaction temperature is 50° C.-100° C., and the optimized modified porous carbon dosage is 80 mg / L-400 mg / L.

[0073] The peroxide solution in the flue heterogeneous three-phase impact reactor 14 is mainly composed of H2O2 and persulfate. The molar concentration of persulfate needs to be maintained between 0.1mol / L and 2.5mol / L, and the molar concentration of H2O2 needs to be maintained between 0.2mol / L and 1.5mol / L. The optimized pH value range of the peroxide solution is 0.08 to 6.0. The mass ratio of the modified biochar and the peroxide solution injected into the flue heterogeneous three-phase impact reactor (14) is 5wt.% to 25wt.%.

[0074] Flue gas pollutants SO2 and NOx Hg 0 and As2O3(As 3+ ) were 100-8000ppm, 100-2500ppm, and 20μg / m 3 ~1200 μg / m 3 and 30 μg / m 3 ~2000 μg / m 3 The optimized particle size of the modified porous carbon is 0.003 μm to 0.5 μm.

[0075] When the flue gas waste heat heater 11 utilizes the flue gas waste heat to dry the modified porous carbon, the operating temperature in the flue gas waste heat heater 11 is not lower than 160° C., and the moisture content of the dried modified porous carbon is not higher than 10%.

[0076] The following are the device's performance on SO2, NO under different conditions: x Hg 0 and As2O3(As 3+ ) Implementation case of simultaneous removal of four flue gas pollutants:

[0077] Example 1:

[0078] The H1 of the advanced oxidation wet spray modification tower is 150 cm and M1 is 10 cm. The initial velocity of the modified solution atomization impact nozzle is 60 m / s. The M2 of the flue heterogeneous three-phase impact reactor is 10 cm. L1 is 60 cm, L2 is 120 cm, and M3 is 20 cm. The initial velocity of the modified porous carbon nozzle is 40 m / s. The microwave radiation power density in the advanced oxidation wet spray modification tower is 400 W / m 3 The thermal radiation power of the superconducting heat pipe is 600W / m 3 The microwave radiation power of the flue heterogeneous three-phase impact reactor is 300W / m 3 The molar concentration of persulfate is 0.1 mol / L, the molar concentration of ammonia water is 0.02 mol / L, and the molar concentration of sodium sulfide is 0.05 mol / L. The pH of the solution is 2.3, the modification temperature is 60°C, and the dosage of modified porous carbon is 120 mg / L. SO2 and NO in flue gas x Hg 0 and As2O3(As 3+ ) concentrations were 1600ppm, 350ppm, and 60μg / m 3 and 120 μg / m 3 .

[0079] The preliminary results of numerical simulation and experimental test are as follows: SO2, NO x Hg 0 and As2O3(As3+ ) and the removal efficiencies can reach 74.3%, 41.1%, 52.4% and 78.9% respectively.

[0080] Example 2:

[0081] The H1 of the advanced oxidation wet spray modification tower is 150 cm and M1 is 10 cm. The initial velocity of the modified solution atomization impact nozzle is 60 m / s. The M2 of the flue heterogeneous three-phase impact reactor is 10 cm. The initial velocity of the modified porous carbon nozzle is 40 m / s. L1 is 60 cm, L2 is 120 cm, and M3 is 20 cm. The microwave radiation power density in the advanced oxidation wet spray modification tower is 600 W / m 3 The thermal radiation power of the superconducting heat pipe is 600W / m 3 The microwave radiation power of the flue heterogeneous three-phase impact reactor is 400W / m 3 The molar concentration of persulfate is 0.2 mol / L, the molar concentration of ammonia water is 0.02 mol / L, and the molar concentration of sodium sulfide is 0.05 mol / L. The pH of the solution is 2.3, the modification temperature is 60°C, and the dosage of modified porous carbon is 120 mg / L. SO2 and NO in flue gas x Hg 0 and As2O3(As 3+ ) concentrations were 1600ppm, 350ppm, and 60μg / m 3 and 120 μg / m 3 .

[0082] The preliminary results of numerical simulation and experimental test are as follows: SO2, NO x Hg 0 and As2O3(As 3+ ) and the removal efficiencies can reach 86.9%, 53.2%, 70.4% and 89.8% respectively.

[0083] Example 3:

[0084] The H1 of the advanced oxidation wet spray modification tower is 150 cm and M1 is 10 cm. The initial velocity of the modified solution atomization impact nozzle is 60 m / s. The M2 of the flue heterogeneous three-phase impact reactor is 10 cm. The initial velocity of the modified porous carbon nozzle is 40 m / s. L1 is 60 cm, L2 is 120 cm, and M3 is 20 cm. The microwave radiation power density in the advanced oxidation wet spray modification tower is 600 W / m 3 The thermal radiation power of the superconducting heat pipe is 600W / m 3 The microwave radiation power of the flue heterogeneous three-phase impact reactor is 400W / m 3The molar concentration of persulfate is 0.4 mol / L, the molar concentration of ammonia water is 0.05 mol / L, and the molar concentration of sodium sulfide is 0.05 mol / L. The pH of the solution is 2.3, the modification temperature is 60°C, and the dosage of modified porous carbon is 120 mg / L. SO2 and NO in flue gas x Hg 0 and As2O3(As 3+ ) concentrations were 1600ppm, 350ppm, and 60μg / m 3 and 120 μg / m 3 .

[0085] The preliminary results of numerical simulation and experimental test are as follows: SO2, NO x Hg 0 and As2O3(As 3+ ) and the removal efficiencies can reach 93.7%, 65.9%, 79.1% and 95.7% respectively.

[0086] Example 4:

[0087] The H1 of the advanced oxidation wet spray modification tower is 150 cm and M1 is 10 cm. The initial velocity of the modified solution atomization impact nozzle is 60 m / s. The M2 of the flue heterogeneous three-phase impact reactor is 10 cm. The initial velocity of the modified porous carbon nozzle is 40 m / s. L1 is 60 cm, L2 is 120 cm, and M3 is 20 cm. The microwave radiation power density in the advanced oxidation wet spray modification tower is 600 W / m 3 The thermal radiation power of the superconducting heat pipe is 600W / m 3 The microwave radiation power of the flue heterogeneous three-phase impact reactor is 400W / m 3 The molar concentration of persulfate is 0.4 mol / L, the molar concentration of ammonia water is 0.1 mol / L, and the molar concentration of sodium sulfide is 0.1 mol / L. The pH of the solution is 2.3, the modification temperature is 80°C, and the dosage of modified porous carbon is 200 mg / L. SO2 and NO in flue gas x Hg 0 and As2O3(As 3+ ) concentrations were 1600ppm, 350ppm, and 60μg / m 3 and 120 μg / m 3 .

[0088] The preliminary results of numerical simulation and experimental test are as follows: SO2, NO x Hg 0 and As2O3(As 3+ ) and the removal efficiencies can reach 100%, 83.4%, 90.6% and 100% respectively.

[0089] Example 5:

[0090] The H1 of the advanced oxidation wet spray modification tower is 150 cm and M1 is 10 cm. The initial velocity of the modified solution atomization impact nozzle is 60 m / s. The M2 of the flue heterogeneous three-phase impact reactor is 10 cm. The initial velocity of the modified porous carbon nozzle is 40 m / s. L1 is 60 cm, L2 is 120 cm, and M3 is 20 cm. The microwave radiation power density in the advanced oxidation wet spray modification tower is 800 W / m 3 The thermal radiation power of the superconducting heat pipe is 600W / m 3 The microwave radiation power of the flue heterogeneous three-phase impact reactor is 600W / m 3 The molar concentration of persulfate is 0.6 mol / L, the molar concentration of ammonia water is 0.1 mol / L, and the molar concentration of sodium sulfide is 0.1 mol / L. The pH of the solution is 2.3, the modification temperature is 80°C, and the dosage of modified porous carbon is 300 mg / L. SO2 and NO in flue gas x Hg 0 and As2O3(As 3+ ) concentrations were 1600ppm, 350ppm, and 60μg / m 3 and 120 μg / m 3 .

[0091] The preliminary results of numerical simulation and experimental test are as follows: SO2, NO x Hg 0 and As2O3(As 3+ ) and the removal efficiencies can reach 100%, 94.7%, 98.8% and 100% respectively.

[0092] Example 6:

[0093] The H1 of the advanced oxidation wet spray modification tower is 150 cm and M1 is 10 cm. The initial velocity of the modified solution atomization impact nozzle is 60 m / s. The M2 of the flue heterogeneous three-phase impact reactor is 10 cm. The initial velocity of the modified porous carbon nozzle is 40 m / s. L1 is 60 cm, L2 is 120 cm, and M3 is 20 cm. The microwave radiation power density in the advanced oxidation wet spray modification tower is 800 W / m 3 The thermal radiation power of the superconducting heat pipe is 600W / m 3 The microwave radiation power of the flue heterogeneous three-phase impact reactor is 600W / m 3The molar concentration of persulfate is 0.8 mol / L, the molar concentration of ammonia water is 0.2 mol / L, and the molar concentration of sodium sulfide is 0.1 mol / L. The pH of the solution is 2.3, the modification temperature is 80°C, and the dosage of modified porous carbon is 300 mg / L. SO2 and NO in flue gas x Hg 0 and As2O3(As 3+ ) concentrations were 1600ppm, 350ppm, and 60μg / m 3 and 120 μg / m 3 .

[0094] The preliminary results of numerical simulation and experimental test are as follows: SO2, NO x Hg 0 and As2O3(As 3+ ) can achieve removal efficiencies of 100%, 100%, 100% and 100% respectively.

[0095] The method of the present invention removes SO2 and NO x Hg 0 and As2O3(As 3+ ) can reach a maximum simultaneous removal efficiency of 100%, 100%, 100% and 100% respectively, with extremely high simultaneous removal efficiency of multiple pollutants, and can achieve the simultaneous removal of single or multiple flue gas pollutants without generating wastewater or waste liquid. It can well meet the current strict ultra-low emission requirements and has extremely significant technical competitive advantages.

[0096] The embodiments described are preferred implementations of the present invention, but the present invention is not limited to the above implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. A system for purifying flue gas by activating free radicals using modified porous carbon, characterized in that: The system comprises an advanced oxidation wet spray modification tower (2) for straw biochar modification and a flue heterogeneous three-phase impact reactor (14) for inducing free radicals / active components to simultaneously desulfurize, denitrify, demercurize and dearsenicize; A plurality of horizontally opposed modified solution atomizing impact nozzles (4) are arranged in pairs on the side wall surface inside the advanced oxidation wet spray modification tower (2); a modified solution and porous carbon mixture (3) is provided at the lower part of the advanced oxidation wet spray modification tower (2); a superconducting heat pipe (5) and a first microwave emitter (6) are arranged in sequence at the upper part; the bottom of the advanced oxidation wet spray modification tower (2) is connected to the liquid-solid material mixing device (1), and the top is connected to the liquid-solid separation device (10); the lower part of the advanced oxidation wet spray modification tower (2) is provided with an advanced oxidation wet spray modification tower total inlet (c), a circulating solution left outlet (e), a circulating solution right outlet (f), and a total outlet (g) for the modified liquid-solid mixture; The flue heterogeneous three-phase impact reactor (14) is provided with a modified porous carbon nozzle (15), a peroxide nozzle (16), a quartz protection device (17), a second microwave emitter (18) and a bag dust collector (19); the flue heterogeneous three-phase impact reactor (14) is connected to the flue gas waste heat heater (11) and the liquid-solid material mixing device (1) through a pipeline; the peroxide nozzle (16) is connected to the peroxide solution device (20) through a pipeline; the modified porous carbon nozzle (15), a peroxide nozzle (16), a quartz protection device (17), a second microwave emitter (18) and a bag dust collector (19) are provided inside the flue heterogeneous three-phase impact reactor (14); the flue heterogeneous three-phase impact reactor (14) is connected to the flue gas waste heat heater (11) and the liquid-solid material mixing device (1) through a pipeline; the peroxide nozzle (16) is connected to the peroxide solution device (20) through a pipeline; the modified porous carbon nozzle (15), a peroxide nozzle (16), a quartz protection device (17), a second microwave emitter (18) and a bag dust collector (19) The carbon nozzle (15) and the peroxide nozzle (16) are both arranged in series and spaced apart in sequence, with the longitudinal and transverse distances M2 being the same. The initial velocity of the modified porous carbon nozzle (15) is between 15.0 m / s and 60 m / s, the distance L2 between the relatively arranged modified porous carbon nozzle (15) and the peroxide nozzle (16) is between 120 cm and 600 cm, and the spacing M3 between the second microwave emitters (18) is between 20 cm and 60 cm.

2. The system for purifying flue gas by activating free radicals using modified porous carbon according to claim 1, characterized in that: The height H1 of the advanced oxidation wet spray modification tower (2) is between 150 cm and 400 cm; the modified solution atomizing counter-impact nozzle (4), the superconducting heat pipe (5) and the first microwave emitter (6) are all arranged in a row, and the three are arranged in sequence and spaced apart from each other, and the longitudinal and transverse spacings M1 between the three are the same, M1 is between 20 cm and 80 cm; the distance L1 between the relatively arranged modified solution atomizing counter-impact nozzles (4) is between 60 cm and 400 cm; the initial velocity of the modified solution atomizing counter-impact nozzle (4) is between 20.0 m / s and 100 m / s.

3. The system for purifying flue gas by activating free radicals using modified porous carbon according to claim 1, characterized in that: The liquid-solid material mixing device (1) is provided with a modified solution inlet (a) of the liquid-solid material mixing device, a biochar inlet (b) of the liquid-solid material mixing device, and a deactivated biochar re-inlet (d) of the liquid-solid material mixing device. The liquid-solid material mixing device (1) is connected to the total inlet (c) of the advanced oxidation wet spray modification tower, and the deactivated biochar re-inlet (d) of the liquid-solid material mixing device is connected to the flue heterogeneous three-phase impact reactor (14) via a pipeline.

4. The system for purifying flue gas by activating free radicals using modified porous carbon according to claim 1, characterized in that: A first solution pump (7) is provided on the pipeline of the left outlet (e) of the circulating solution of the advanced oxidation wet spray modification tower (2), a second solution pump (8) is provided on the pipeline of the right outlet (f) of the circulating solution, and a third solution pump (9) is provided on the pipeline of the total outlet (g) of the modified liquid-solid mixture and the total inlet (h) of the liquid-solid rapid separator mixture; a first fan (12) is provided on the connecting pipeline between the flue gas waste heat heater (11) and the flue heterogeneous three-phase impact reactor (14).

5. The system for purifying flue gas by activating free radicals using modified porous carbon according to claim 3, characterized in that: A bag filter (19) is provided at the end of the flue heterogeneous three-phase impact reactor (14); the bag filter outlet (n) is sequentially connected to a product desorption and washing system (21) and a product separation system (22); the product separation system (22) is connected to a deactivated biochar re-inlet (d) of a liquid-solid material mixing device; and the deactivated biochar in the flue heterogeneous three-phase impact reactor (14) is recycled.

6. A method for purifying a flue gas system by activating free radicals using modified porous carbon according to any one of claims 1 to 5, characterized in that: The operation process of the biochar modification and pollutant removal system is as follows: I. The modified solution enters the liquid-solid material mixing device (1) from the modified solution inlet (a) of the liquid-solid material mixing device, and the straw biochar enters the liquid-solid material mixing device (1) from the biochar inlet (b) of the liquid-solid material mixing device; the straw biochar and the modified solution are mixed evenly in the liquid-solid material mixing device (1) and then enter the bottom of the advanced oxidation wet spray modification tower (2) through the main inlet (c) of the advanced oxidation wet spray modification tower; the first solution pump (7) and the second solution pump (8) are simultaneously started to pump the liquid-solid mixture through the modified solution atomization counter-impact nozzles (4) on both sides to spray it horizontally into the modification zone to implement activation modification of the biochar; at the same time, the superconducting heat pipe (5) and the first microwave emitter (6) are started to radiate the flue gas waste heat and microwaves to activate the modified solution and generate highly active free radicals / active components; The generated highly active free radicals / active components simultaneously activate and modify the straw biochar to prepare modified porous carbon with a developed pore structure and abundant surface functional groups. II. The modified porous carbon modified in the advanced oxidation wet spray modification tower (2) is sucked from the total outlet (g) of the modified liquid-solid mixture by the third solution pump (9) and sent to the liquid-solid separation device (10) for liquid-solid separation; the separated modified porous carbon enters the flue gas waste heat heater (11) for flue gas waste heat drying, and then is sent by the first fan (12) to the flue heterogeneous three-phase impact reactor (14) for free radical activation and oxidative adsorption removal of pollutants; the separated waste solution is sent again to the advanced oxidation wet spray modification tower from the liquid-solid rapid separator solution outlet (i) Reuse is implemented in the tower (2). In the advanced oxidation wet spray modification tower (2), the superconducting heat pipe (5) uses the waste heat of the flue gas to achieve rapid heating and temperature increase of the material, and the microwaves emitted by the first microwave emitter (6) achieve rapid pore expansion of the biochar. The two can also synergistically activate the modification solution to induce highly active free radicals / active components to modify the porous carbon, and generate highly active functional groups on its surface, which are then used to further activate peroxides to generate free radicals for oxidative removal of pollutants, thereby achieving the multi-component synergistic effects of biochar pore expansion, surface functional group generation, free radical activation, and multiphase mass transfer enhancement. III. Flue gas from a coal-fired boiler enters the reaction zone of a flue heterogeneous three-phase impact reactor; a modified porous carbon nozzle (15) and a peroxide nozzle (16) spray modified porous carbon and peroxide solution into the reaction zone, respectively. Simultaneously, a second microwave emitter (18) is turned on to cooperate with the modified porous carbon to activate the free radicals / active components induced by the persulfate solution in the reaction zone of the flue heterogeneous three-phase impact reactor, SO4 - OH, HO2, O and O2 1 , and SO2 and NO in flue gas x 、Hg 0 and As 3+ Simultaneous oxidation and removal reaction occurs, and SO2 and NO x 、Hg 0 and As 3+ Oxidized to H2SO4, HNO3, Hg 2+ and As 5+ , achieving simultaneous removal of multiple pollutants from flue gas; after being used, the inactivated porous carbon is captured by the bag filter (19) at the tail end, and then sent by the fan (13) through the liquid-solid material mixing device to the inactivated biochar re-inlet (d) into the advanced oxidation wet spray modification tower (2) for further modification to achieve repeated reuse; IV. The adsorption saturated porous carbon is desorbed and separated from the adsorbed products on the porous carbon by high temperature desorption and hot water washing in the product desorption and washing system (21). The desorbed products H2SO4, HNO3, Hg 2+ and As 5+ Entering the product separation system (22) to implement multi-stage comprehensive resource utilization; the multi-stage comprehensive resource utilization system includes a mercury / arsenic separation device, an ammonia acid neutralization device and a flue gas waste heat evaporation crystallization fertilizer preparation device; In the mercury / arsenic separation unit, Hg 2+ and As 5+ By adding divalent sulfide ions to react, mercury sulfide and arsenic sulfide are produced and then separated and recovered. In the ammonia neutralization acid device, H2SO4 and HNO3 can react with the addition of ammonia to produce ammonium sulfate and ammonium nitrate. In the flue gas waste heat evaporation crystallization fertilizer preparation device, agricultural fertilizer is prepared after evaporation crystallization by boiler flue gas waste heat.

7. The method for purifying flue gas by activating free radicals using modified porous carbon according to claim 6, characterized in that: The flue gas pollutants SO2 and NO x Hg 0 The initial concentration ranges of As2O3 and As2O3 were 100~8000ppm, 100~2500ppm and 20μg / m 3 ~1200 μg / m 3 and 30 μg / m 3 ~2000 μg / m 3 ; The particle size of the modified porous carbon is 0.003μm~0.5μm; when the flue gas waste heat heater (11) uses the flue gas waste heat to dry the modified porous carbon, the operating temperature inside the flue gas waste heat heater (11) is not lower than 160°C, and the moisture content of the modified porous carbon after drying is not higher than 10%.

8. The method for purifying flue gas by activating free radicals using modified porous carbon according to claim 6, characterized in that: The microwave radiation power density in the advanced oxidation wet spray modification tower (2) is maintained at 300W / m 3 ~2000W / m 3 The thermal radiation power of the superconducting heat pipe is maintained at 600W / m 3 ~5000W / m 3 The microwave radiation power in the flue heterogeneous three-phase impact reactor (14) is maintained at 200W / m 3 ~1500W / m 3 between.

9. The method for purifying flue gas by activating free radicals using modified porous carbon according to claim 6, characterized in that: The modified solution used in the advanced oxidation wet spray modification tower (2) is composed of a mixture of persulfate, ammonia water and sodium sulfide, the molar concentration of persulfate is maintained between 0.05mol / L and 2.0mol / L, the molar concentration of ammonia water is maintained between 0.02mol / L and 1.0mol / L, and the molar concentration of sodium sulfide is maintained between 0.05mol / L and 2.0mol / L; the peroxide solution in the flue heterogeneous three-phase impact reactor (14) is composed of H2O2 and persulfate; the molar concentration of persulfate is maintained at 0.1mol / L. l / L~2.5mol / L, the molar concentration of H2O2 is maintained between 0.2mol / L~1.5mol / L, and the pH value of the peroxide solution ranges from 0.08 to 6.0; the mass ratio of the modified biochar and the peroxide solution sprayed into the flue heterogeneous three-phase impact reactor (14) is 5wt.%~25wt.%; the pH value of the modified solution in the advanced oxidation wet spray modification tower (2) ranges from 0.05 to 6.5, the reaction temperature is 50℃~100℃, and the dosage of the modified porous carbon is 80mg / L~400mg / L.

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