A dual-stage activated carbon multi-pollutant control system and method under clean fuel blending and deep peak shaving

Abstract

A kind of clean fuel blending and deep peak shaving under two-stage activated carbon multi-pollutant control system and method, it relates to industrial flue gas treatment field.The temperature feedback controller is set before denitration tower entrance, entrance is set ammonia grid, inside is set vanadium tungsten titanium base catalyst layer with porous uniform distribution board, outlet is communicated with adsorption flue, activated carbon first storage bin is connected with activated carbon first injector and porous uniform distribution board is communicated, activated carbon second storage bin is connected with activated carbon second injector and adsorption flue is communicated, adsorption flue is divided into two ways after being connected with activated carbon separator, one way is returned to activated carbon second storage bin through activated carbon regeneration device, another way is connected with chimney through bag filter and desulfurization tower, carries multi-pollutant monitoring unit and two-stage activated carbon linkage injection controller. Through grading activated carbon injection and linkage control, it can realize wide temperature range denitration intensification and multi-pollutant synergistic removal, improve the adaptation ability of system to complex working condition.

Description

Technical Field

[0001] This invention relates to the field of industrial flue gas treatment technology, specifically a two-stage activated carbon multi-pollutant control system and method under clean fuel co-firing and deep peak shaving. Background Technology

[0002] Coal, as a pillar of my country's energy system, will continue to play a fundamental role in ensuring energy security and stable power supply in the medium to long term. With the advancement of new power system construction, coal-fired power generation technology is accelerating its transformation towards deep decarbonization and flexibility. Among these advancements, the high-proportion blending of clean fuels such as biomass and green ammonia in coal-fired boilers is a crucial technological path to reduce fossil carbon emissions and promote the low-carbon transformation of thermal power. Compared to conventional coal-fired flue gas, the composition of pollutants in flue gas after the high-proportion blending of clean fuels is more complex, with a significant increase in the concentrations of pollutants such as nitrogen oxides, escaped ammonia, alkali metals, hydrogen chloride, and VOCs. Simultaneously, the flexible operation of coal-fired units requires deep peak-shaving capabilities. Under peak-shaving conditions, frequent changes in boiler load result in wide fluctuations in flue gas temperature, flow rate, and pollutant concentrations, severely restricting ultra-low emissions of flue gas pollutants and the control of ammonia escape.

[0003] Current flue gas pollutant control systems for coal-fired boilers typically consist of a denitrification unit, a dust removal unit, and a wet desulfurization unit, enabling efficient removal of conventional pollutants such as nitrogen oxides, particulate matter, and sulfur dioxide under design load and stable operating conditions. However, under conditions of high-proportion co-firing and deep peak-shaving operation, traditional pollutant control systems suffer from insufficient adaptability and limited dynamic control capabilities, with the denitrification unit being particularly affected. Existing denitrification systems mostly employ ammonia selective catalytic reduction (NH3-SCR) technology with vanadium-tungsten-titanium-based catalysts as the core, typically operating at a temperature window of 300-400℃. When the unit enters low-load operation, the flue gas temperature can drop below 280℃, causing a decrease in the activity of conventional SCR catalysts and a reduction in nitrogen oxide removal efficiency. If the denitrification efficiency is maintained by increasing the ammonia injection rate, it can easily lead to increased ammonia escape, further inducing corrosion, blockage, and secondary pollution problems in downstream equipment.

[0004] Furthermore, unconventional pollutants such as hydrogen chloride, alkali metals, and VOCs introduced or enhanced by the co-firing of clean fuels are difficult to remove efficiently and synergistically using traditional "denitrification-dust removal-desulfurization" pollutant control processes. For example, straw-based biomass typically contains high levels of chlorine and alkali metals such as potassium and sodium. During combustion, it easily generates corrosive or adhesive components such as HCl, KCl, NaCl, and alkali metal aerosols, which not only affect the safe and stable operation of downstream equipment but may also exacerbate catalyst poisoning, flue dust accumulation, and corrosion of heated surfaces. Traditional wet desulfurization systems primarily target SO2 removal, and dust removal systems primarily target particulate matter capture, making it difficult to rapidly respond to and synergistically control multiple unconventional pollutants such as escaping ammonia, HCl, alkali metals, and VOCs.

[0005] Activated carbon materials possess a well-developed pore structure, a large specific surface area, and tunable surface functional groups, combining low-temperature NH3-SCR catalytic activity with multi-pollutant adsorption capacity. This provides a new technical approach to addressing the decline in low-temperature denitrification efficiency under deep peak-shaving conditions and the synergistic removal of unconventional pollutants under clean fuel blending conditions. Therefore, it is urgent to develop a multi-pollutant synergistic control scheme for flue gas based on the rational application of activated carbon. This scheme should be adaptable to high-proportion clean fuel blending and deep peak-shaving conditions, enabling it to both enhance the NH3-SCR denitrification reaction at low temperatures and dynamically adsorb and remove unconventional pollutants such as escaped ammonia, hydrogen chloride, alkali metals, and VOCs from the denitrified flue gas. This would improve the wide-temperature-range adaptability, dynamic control capability, and multi-pollutant synergistic purification capability of existing coal-fired boiler flue gas pollutant control systems. Summary of the Invention

[0006] To address the problems of decreased denitrification efficiency, increased ammonia slip, and insufficient synergistic control of unconventional pollutants in existing pollutant control systems under conditions of high-proportion clean fuel blending and deep peak shaving, this invention provides a two-stage activated carbon multi-pollutant control system and method under clean fuel blending and deep peak shaving. Through staged activated carbon injection and linkage regulation, it can achieve enhanced denitrification over a wide temperature range and synergistic removal of multiple pollutants, improving the system's adaptability to complex operating conditions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A dual-stage activated carbon multi-pollutant control system for clean fuel co-firing and deep peak shaving includes a denitrification tower, an ammonia injection grid, a vanadium-tungsten-titanium-based catalyst layer, a bag filter, a desulfurization tower, and a chimney. The ammonia injection grid is located at the inlet of the denitrification tower and connected to an external ammonia supply pipeline. The vanadium-tungsten-titanium-based catalyst layer adopts a multi-layer structure and is spaced along the axial direction inside the denitrification tower. The system also includes a temperature feedback controller, a primary activated carbon storage bin, a primary activated carbon injector, a porous uniform distribution plate, an adsorption flue, a secondary activated carbon storage bin, a secondary activated carbon injector, a baffle plate, a multi-pollutant monitoring unit, a dual-stage activated carbon linkage injection controller, an activated carbon separator, and an activated carbon regeneration device. The temperature feedback controller is set at the flue gas duct before the inlet of the denitrification tower to monitor the flue gas temperature in real time and provide feedback signals; the porous uniformly distributed plate is set in the interval area of ​​the vanadium-tungsten-titanium-based catalyst layer; the activated carbon primary storage silo is connected to the activated carbon primary injector through a conveying pipeline; the activated carbon primary injector is set on the side of the denitrification tower and communicates with the porous uniformly distributed plate inside the denitrification tower. The outlet of the denitrification tower is connected to the inlet of the adsorption flue. The activated carbon secondary storage silo is connected to the activated carbon secondary injector through a conveying pipeline. The activated carbon secondary injector is installed on the adsorption flue and is connected to the inside of the adsorption flue. The baffle is installed inside the adsorption flue and is located in the adjacent area of ​​the activated carbon secondary injector. The outlet of the adsorption flue is connected to the inlet of the activated carbon separator, the solid outlet of the activated carbon separator is connected to the activated carbon regeneration device, the outlet of the activated carbon regeneration device is connected to the activated carbon secondary storage silo through a reuse pipeline, the flue gas outlet of the activated carbon separator is connected to the inlet of the bag filter, the outlet of the bag filter is connected to the inlet of the desulfurization tower, and the outlet of the desulfurization tower is connected to the chimney. The multi-pollutant monitoring unit is connected to the inlet flue of the denitrification tower, the outlet flue of the denitrification tower, and the outlet flue of the adsorption flue, respectively. The dual-stage activated carbon linkage injection controller is connected to the temperature feedback controller, the first-stage activated carbon injector, the second-stage activated carbon injector, and the multi-pollutant monitoring unit, respectively, and dynamically adjusts the injection volume of the two-stage activated carbon according to the flue gas temperature and pollutant concentration.

[0008] Furthermore, the primary activated carbon sprayed by the primary activated carbon injector is in powder or granular form, with a particle size of 10~100μm and a specific surface area of ​​1000~1700m². 2 / g, the pore structure is microporous; the surface of the primary activated carbon contains nitrogen-containing functional groups, and the nitrogen content is 1~8 at.%, the nitrogen-containing functional groups include one or more of pyridine nitrogen, pyrrole nitrogen, and graphitic nitrogen; the mass ratio of primary activated carbon to vanadium-tungsten-titanium-based catalyst layer is 1:100~10:100.

[0009] Furthermore, the secondary activated carbon sprayed by the secondary activated carbon injector is in powder form, with a particle size of 10~100μm and a specific surface area of ​​500~1000m². 2 / g, total pore volume is 0.3~1.0cm³ 3 / g; the secondary activated carbon has a hierarchical pore structure, including micropores, mesopores and macropores, of which the pore volume of mesopores and macropores accounts for 20% to 60% of the total pore volume; the surface of the secondary activated carbon contains oxygen-containing functional groups and / or nitrogen-containing functional groups, with an oxygen content of 5 to 10 at.% and a nitrogen content of 2 to 10 at.%.

[0010] Furthermore, the activated carbon separator is a cyclone separator, an inertial separator, a ceramic filter separator, or a combination thereof, with a separation efficiency of 80% to 99% for activated carbon; the activated carbon regeneration device adopts a thermal regeneration method, with a regeneration temperature of 150 to 300°C, a regeneration atmosphere of nitrogen, water vapor, or a mixture thereof, and a regeneration time of 10 to 120 minutes.

[0011] Furthermore, the control logic of the dual-stage activated carbon linkage injection controller is as follows: when the flue gas temperature at the inlet of the denitrification tower is below 300℃, the first-stage activated carbon injector is activated; when the NH3 concentration at the outlet of the denitrification tower is above 3~5ppm, the HCl concentration is above 10ppm, or the VOCs concentration is above 20mg / Nm³, the first-stage activated carbon injector is activated. 3 When the pollutant concentration is below the set value, the secondary activated carbon injector is activated; when the pollutant concentration is below the set value, the corresponding activated carbon injection rate is reduced.

[0012] A method for controlling multiple pollutants using dual-stage activated carbon under clean fuel blending and deep peak shaving includes the following steps: S1. Real-time Operating Condition Monitoring: Before the flue gas from the coal-fired boiler enters the denitrification tower, the flue gas temperature is monitored in real time by a temperature feedback controller and fed back to the two-stage activated carbon linkage injection controller; simultaneously, the NO2 concentration in the inlet flue, outlet flue, and adsorption flue outlet flue of the denitrification tower is monitored by a multi-pollutant monitoring unit. x The concentrations of NH3, HCl, and VOCs, as well as the flue gas flow rate, are monitored online, and the monitoring signals are transmitted to the two-stage activated carbon linkage injection controller to determine the current operating condition of the system. S2. Staged Denitrification Reaction: When the flue gas temperature at the inlet of the denitrification tower is detected to be 300~400℃, NH3 reducing agent is injected into the flue gas entering the denitrification tower through the ammonia injection grid, reducing the NO in the flue gas. x NO undergoes a selective catalytic reduction reaction with NH3 on the surface of the vanadium-tungsten-titanium-based catalyst layer, achieving NO under rated operating conditions. x Removal; When the flue gas temperature is detected to be below 300℃, the dual-stage activated carbon linkage injection controller activates the primary activated carbon injector. The primary activated carbon is uniformly distributed and rectified by a porous uniform distribution plate and then uniformly adheres to the surface of the vanadium-tungsten-titanium-based catalyst layer, forming an activated carbon-vanadium-tungsten-titanium-based catalyst composite denitrification system, which enhances NO removal under low-temperature conditions. x Remove; S3, Secondary Synergistic Adsorption: When an increase in the concentration of NH3, HCl or VOCs at the outlet of the denitrification tower is detected, or when the demand for removal of unconventional pollutants increases, the dual-stage activated carbon linkage injection controller starts the secondary activated carbon injector to inject secondary activated carbon into the adsorption flue. Under the action of the baffle, the secondary activated carbon is fully turbulently mixed with the flue gas to adsorb and capture escaped ammonia, HCl, alkali metals and VOCs in the denitrification flue gas. S4. Flue gas purification and emission: After being treated by the adsorption flue, the flue gas enters the activated carbon separator to complete gas-solid separation. The separated flue gas first enters the bag filter to remove residual particulate matter, then enters the desulfurization tower to remove SO2, and finally is emitted through the chimney. S5. Activated carbon regeneration and reuse: The activated carbon enriched with pollutants obtained by the activated carbon separator is sent to the activated carbon regeneration device for thermal regeneration treatment. The activated carbon that meets the performance standards after regeneration is returned to the secondary activated carbon storage silo for recycling.

[0013] Furthermore, in step S2, the ammonia injection grid controls the mixing of NH3 and NO. x The molar ratio is 0.8~1.2, and the mass ratio of primary activated carbon to vanadium-tungsten-titanium-based catalyst layer is 1:100~10:100.

[0014] Furthermore, in step S5, when the specific surface area retention rate of the regenerated activated carbon is less than 70%, or the adsorption capacity of pollutants is less than 60% of that of the fresh activated carbon, the portion of activated carbon is discharged from the system and fresh activated carbon is added.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. Wide temperature range denitrification adaptation: By setting up a primary activated carbon injection unit in the denitrification tower, activated carbon and vanadium-tungsten-titanium-based catalyst form a composite denitrification system under low temperature conditions, which makes up for the deficiency of low temperature activity of conventional catalysts, improves the denitrification efficiency under deep peak shaving and low load conditions, and reduces the risk of ammonia escape caused by excessive ammonia injection. 2. Synergistic removal of multiple pollutants: A secondary activated carbon injection unit is set up after the denitrification tower, which can simultaneously adsorb and remove unconventional pollutants such as ammonia, hydrogen chloride, alkali metals and VOCs that escape from the large-scale co-firing of clean fuels, making up for the shortcomings of the traditional "denitrification-dust removal-desulfurization" process. 3. Dynamic and precise control: Based on flue gas temperature and online monitoring data of multiple pollutants, the injection volume of the two-stage activated carbon is dynamically adjusted through the dual-stage activated carbon linkage injection controller. This can adapt to peak-shaving conditions with wide fluctuations in flue gas parameters and reduce activated carbon consumption while ensuring compliance with emission standards. 4. Activated carbon recycling: Equipped with an activated carbon separation and thermal regeneration unit, the activated carbon after secondary adsorption can be regenerated and recycled, reducing the material consumption cost of the system operation. 5. Strong system compatibility for modification: It can be retrofitted and modified on the basis of existing conventional coal-fired flue gas treatment processes, and is suitable for the low-carbon and flexible upgrade of in-service coal-fired units. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the control system of the present invention.

[0017] In the diagram: 1. Temperature feedback controller; 2. Denitrification tower; 3. Ammonia injection grid; 4. Vanadium-tungsten-titanium-based catalyst layer; 5. Porous uniform distribution plate; 6. Primary activated carbon storage silo; 7. Primary activated carbon injector; 8. Secondary activated carbon storage silo; 9. Secondary activated carbon injector; 10. Adsorption flue; 11. Baffle plate; 12. Multi-pollutant monitoring unit; 13. Dual-stage activated carbon linkage injection controller; 14. Activated carbon separator; 15. Activated carbon regeneration device; 16. Bag filter; 17. Desulfurization tower; 18. Chimney. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] A two-stage activated carbon multi-pollutant control system for clean fuel blending and deep peak shaving, the structure of which is described in [reference needed]. Figure 1 As shown, the system includes a temperature feedback controller 1, a denitrification tower 2, an ammonia injection grid 3, a vanadium-tungsten-titanium-based catalyst layer 4, a porous uniformly distributed plate 5, a primary activated carbon storage silo 6, a primary activated carbon injector 7, a secondary activated carbon storage silo 8, a secondary activated carbon injector 9, an adsorption flue 10, a baffle plate 11, a multi-pollutant monitoring unit 12, a dual-stage activated carbon linkage injection controller 13, an activated carbon separator 14, an activated carbon regeneration device 15, a bag filter 16, a desulfurization tower 17, and a chimney 18, as detailed below: For the high-proportion blending of clean fuels, where clean fuels include biomass, ammonia, and methanol, and the preferred biomass is straw-based biomass, including one or more of rice straw, wheat straw, and corn straw; where high proportion refers to blending, meaning that the blended fuel accounts for more than 50% of the fuel input.

[0020] The control system structure described in this invention is as follows: The temperature feedback controller 1 is located at the flue before the inlet of the denitrification tower 2. It is used to monitor the temperature of the flue gas before entering the denitrification tower 2 in real time and to feed the temperature signal back to the dual-stage activated carbon linkage injection controller 13.

[0021] The flue gas temperature before the inlet of the denitrification tower 2 is 200℃~400℃. When the flue gas temperature is 300℃~400℃, the system relies on the vanadium-tungsten-titanium-based catalyst layer 4 to carry out the conventional NH3-SCR denitrification reaction. When the flue gas temperature is below 300℃, the dual-stage activated carbon linkage injection controller 13 starts the activated carbon primary injector 7 according to the temperature feedback signal to enhance the low-temperature denitrification process.

[0022] In addition, the pollutants in the flue gas at the inlet of denitrification tower 2 include NO. x SO2, alkali metals, HCl and VOCs, of which: NO x Concentration of 100~600 mg / Nm 3 The preferred concentration is 200~450 mg / Nm³. 3 SO2 concentration is 200~2000 mg / Nm³ 3 Preferably, it is 500~1500 mg / Nm 3Alkali metals include sodium, potassium and their oxides, chlorides and sulfates in aerosols; HCl concentration is 10~300ppm, preferably 30~200ppm; VOCs concentration is 10~200mg / Nm³. 3 Preferably, it is 20~150 mg / Nm 3 The pollutants at the outlet of denitrification tower 2 also include escaped NH3, with a concentration of 0~50 ppm, preferably controlled below 10 ppm.

[0023] The ammonia injection grille 3 is located at the inlet of the top of the denitrification tower 2 and is connected to the external ammonia supply pipeline. It is used to inject NH3 reducing agent into the flue gas entering the denitrification tower 2. The ammonia injection grille 3 controls the reaction between NH3 and NO. x The molar ratio is 0.8~1.2, preferably 1:1, to meet the requirements of NH3-SCR denitrification reaction and reduce the risk of ammonia escape caused by excessive ammonia injection.

[0024] The vanadium-tungsten-titanium-based catalyst layer 4 adopts a multi-layer structure and is spaced along the axial direction inside the denitrification tower 2 to catalyze the removal of NO from the flue gas. x It undergoes a selective catalytic reduction reaction with NH3 to achieve NO under rated operating conditions. x Removal. Preferably, the vanadium-tungsten-titanium-based catalyst layer 4 is a honeycomb vanadium-tungsten-titanium-based catalyst layer with 3 to 5 layers. Under rated load and suitable temperature conditions, the vanadium-tungsten-titanium-based catalyst layer 4 is used to remove NO. x Highly efficient removal; under low load or deep peak shaving conditions, the vanadium-tungsten-titanium-based catalyst layer 4 and the activated carbon primary injector 7 work synergistically to improve the low-temperature NH3-SCR denitrification efficiency.

[0025] The porous uniformly distributed plate 5 is disposed in the interval region of the vanadium-tungsten-titanium-based catalyst layer 4 to uniformly distribute and rectify the activated carbon injected by the primary activated carbon injector 7, so that the primary activated carbon is uniformly dispersed and adheres to the surface of the vanadium-tungsten-titanium-based catalyst layer 4, thereby enhancing the denitrification reaction under low-load conditions. To improve the utilization rate of the porous uniformly distributed plate 5, two porous uniformly distributed plates 5 can be respectively disposed in the two interval regions at the bottom of the vanadium-tungsten-titanium-based catalyst layer 4, thereby controlling the number of porous uniformly distributed plates 5 used while ensuring the effectiveness of the primary activated carbon.

[0026] The primary activated carbon storage silo 6 is connected to the primary activated carbon injector 7 via a conveying pipeline. It is used to store and supply primary activated carbon to the surface of the vanadium-tungsten-titanium-based catalyst layer 4. The primary activated carbon injector 7 is located on the side of the denitrification tower 2 and is connected to the porous uniformly distributed plate 5 inside the denitrification tower 2 via branch pipelines. The primary activated carbon is in powder or granular form, with a particle size of 10-100 μm, preferably 20-60 μm, and a specific surface area of ​​1000-1700 m². 2 / g, with a pore structure dominated by micropores, used for enriching NOx It also provides NH3 and a large number of active sites. Furthermore, the surface of the primary activated carbon contains nitrogen-containing functional groups, including one or more of pyridine nitrogen, pyrrole nitrogen, and graphitic nitrogen, with a nitrogen content of 1-8 at.%, preferably 2-6 at.%. These nitrogen-containing functional groups are used to regulate the acid-base properties of the activated carbon surface and increase NO content. x The activated carbon enhances the adsorption and enrichment capacity of NH3 and provides activation capacity for O2 at low temperatures, thereby strengthening the synergistic denitrification effect between the primary activated carbon and the vanadium-tungsten-titanium-based catalyst layer 4. Furthermore, the mass ratio of the primary activated carbon to the vanadium-tungsten-titanium-based catalyst layer 4 is 1:100 to 10:100, preferably 3:100 to 6:100, allowing the primary activated carbon to form a dispersed covering layer on the surface of the vanadium-tungsten-titanium-based catalyst layer 4, while avoiding excessive accumulation of activated carbon that could clog catalyst channels or significantly increase system pressure drop.

[0027] The inlet of the adsorption flue 10 is connected to the outlet at the bottom of the denitrification tower 2, and is used to receive the flue gas after denitrification treatment, and to provide space for the contact adsorption of residual unconventional pollutants in the flue gas by the secondary activated carbon. The outlet of the adsorption flue 10 is connected to the inlet of the activated carbon separator 14, and is used to separate the flue gas and activated carbon. A baffle 11 is provided inside the adsorption flue 10. The baffle 11 is located in the area adjacent to the secondary activated carbon injector 9, and is used to enhance the turbulent mixing and mass transfer contact between the flue gas and the secondary activated carbon, and improve the adsorption and removal efficiency of pollutants such as escaped ammonia, hydrogen chloride, alkali metals and VOCs.

[0028] The activated carbon secondary storage silo 8 is connected to the activated carbon secondary injector 9 via a conveying pipeline. It is used to store and supply secondary activated carbon to the area of ​​the baffle 11 inside the adsorption flue 10. The activated carbon secondary injector 9 is positioned above the adsorption flue 10 and communicates with the interior of the adsorption flue 10. The secondary activated carbon is powdered activated carbon with a particle size of 10-100 μm, preferably 30-80 μm; and a specific surface area of ​​500-1000 m². 2 / g, total pore volume is 0.3~1.0cm³ 3 / g; The secondary activated carbon has a hierarchical pore structure, including micropores, mesopores, and macropores. Micropores provide adsorption capacity for pollutants such as NH3, HCl, and VOCs, while mesopores and macropores provide rapid mass transfer channels to accommodate rapid fluctuations in pollutant concentrations under deep peak-shaving conditions. Preferably, the mesopore and macropore volume of the secondary activated carbon accounts for 20%–60% of the total pore volume, more preferably 40%–50%, to balance adsorption capacity and mass transfer rate. Furthermore, the surface of the secondary activated carbon contains oxygen-containing functional groups and / or nitrogen-containing functional groups to enhance the adsorption of escaped ammonia, hydrogen chloride, and VOCs, wherein the oxygen content is 5–10 at.% and the nitrogen content is 2–10 at.%. The oxygen-containing functional groups include one or more of hydroxyl, carboxyl, carbonyl, and ether bonds; the nitrogen-containing functional groups include one or more of pyridine nitrogen, pyrrole nitrogen, and graphitic nitrogen.

[0029] The solid outlet of the activated carbon separator 14 is connected to the activated carbon regeneration device 15 for regenerating the activated carbon enriched with pollutants obtained from the separation. The outlet of the activated carbon regeneration device 15 is connected to the secondary activated carbon storage silo 8 through a reuse pipeline, so that the regenerated activated carbon can be recycled. The flue gas outlet of the activated carbon separator 14 is connected to the inlet of the bag filter 16 for further capturing fly ash, dust and residual activated carbon in the flue gas. The outlet of the bag filter 16 is connected to the inlet of the desulfurization tower 17 for further removing SO2 from the flue gas. The outlet of the desulfurization tower 17 is connected to the chimney 18 for discharging the purified flue gas. The activated carbon separator 14 is a cyclone separator, inertial separator, ceramic filter separator, or a combination thereof, suitable for separating powdered activated carbon with a particle size of 10~100μm. The separation efficiency of the activated carbon separator 14 is 80%~99%, more preferably 90%~98%. The activated carbon regeneration device 15 adopts a thermal regeneration method, with a regeneration temperature of 150~300℃, a regeneration atmosphere of nitrogen, water vapor, or a mixture thereof, and a regeneration time of 10~120min. Through regeneration, NH3, HCl, VOCs, and other pollutants adsorbed on the pores and surface of the activated carbon are desorbed, thereby restoring the adsorption performance of the activated carbon. Furthermore, when the specific surface area retention rate of the regenerated activated carbon is less than 70%, or the pollutant adsorption capacity is less than 60% of that of the fresh activated carbon, this portion of activated carbon is discharged from the system and fresh activated carbon is added to ensure the adsorption and removal effect of the secondary activated carbon on escaped ammonia, HCl, VOCs, and alkali metal pollutants.

[0030] The multi-pollutant monitoring unit 12 is connected to the inlet flue of the denitrification tower 2, the outlet flue of the denitrification tower 2, and the outlet flue of the adsorption flue 10, respectively, and is used for online monitoring of NO in the flue gas. xThe system monitors parameters such as NH3, HCl, VOCs concentrations, and flue gas flow rate. The dual-stage activated carbon linkage injection controller 13 is connected to the temperature feedback controller 1, the primary activated carbon injector 7, the secondary activated carbon injector 9, and the multi-pollutant monitoring unit 12, respectively, to dynamically adjust the injection volume of the primary and secondary activated carbon based on changes in flue gas temperature and pollutant concentrations. Preferably, when the flue gas temperature at the inlet of the denitrification tower 2 is below 300℃, the dual-stage activated carbon linkage injection controller 13 activates the primary activated carbon injector 7. When the NH3 concentration at the outlet of the denitrification tower 2 is higher than 3-5 ppm, the HCl concentration is higher than 10 ppm, or the VOCs concentration is higher than 20 mg / Nm³, the system activates the primary activated carbon injector 7. 3 When the concentration of the above-mentioned pollutants is lower than the set value, the corresponding activated carbon injection amount is reduced to reduce activated carbon consumption and maintain stable system operation.

[0031] Based on the above system, a two-stage activated carbon method for controlling multiple pollutants under clean fuel blending and deep peak shaving is proposed, including the following steps: S1. Real-time monitoring of operating conditions: Before the flue gas generated by the coal-fired boiler enters the denitrification tower 2, the flue gas temperature is first monitored in real time by the temperature feedback controller 1, and the temperature signal is fed back to the dual-stage activated carbon linkage injection controller 13; at the same time, the multi-pollutant monitoring unit 12 monitors the NO in the inlet flue, outlet flue, and outlet flue of the adsorption flue 10 of the denitrification tower 2. x The system monitors parameters such as NH3, HCl, VOCs concentrations and flue gas flow rate online and transmits the monitoring signals to the dual-stage activated carbon linkage injection controller 13. The dual-stage activated carbon linkage injection controller 13 determines the current operating condition of the system based on changes in flue gas temperature, pollutant concentration and flue gas flow rate.

[0032] S2. Staged Denitrification Reaction: When the temperature feedback controller 1 detects that the flue gas temperature at the inlet of denitrification tower 2 is 300~400℃, the ammonia injection grid 3 injects NH3 reducing agent into the flue gas entering denitrification tower 2, reducing the NO in the flue gas. x The vanadium-tungsten-titanium-based catalyst layer 4 undergoes a selective catalytic reduction reaction with NH3 to generate N2 and H2O, achieving NO reduction under normal load or rated operating conditions. xRemoval; When the temperature feedback controller 1 detects that the flue gas temperature at the inlet of the denitrification tower 2 is lower than 300℃, the dual-stage activated carbon linkage injection controller 13 starts the activated carbon primary injector 7. The primary activated carbon in the primary activated carbon storage silo 6 enters the primary activated carbon injector 7 through the conveying pipeline. After being evenly distributed and rectified by the porous uniform distribution plate 5, the injected primary activated carbon is uniformly dispersed and adheres to the surface of the vanadium-tungsten-titanium-based catalyst layer 4, forming an activated carbon-vanadium-tungsten-titanium-based catalyst composite denitrification system. On the one hand, the low-temperature catalytic active sites of activated carbon participate in the NH3-SCR reaction; on the other hand, the pore structure of activated carbon is used to enrich NO. x And NH3, increasing the local reactant concentration on the catalyst surface, thereby enhancing NO under low-temperature conditions. x It removes and reduces the risk of ammonia escape caused by excessive ammonia injection.

[0033] S3, Secondary Synergistic Adsorption: When the multi-pollutant monitoring unit 12 detects an increase in the concentration of NH3, HCl, or VOCs at the outlet of the denitrification tower 2, or when the demand for removal of unconventional pollutants increases based on the proportion of clean fuel blending and the deep peak shaving status, the dual-stage activated carbon linkage injection controller 13 activates the secondary activated carbon injector 9. The secondary activated carbon in the secondary activated carbon storage silo 8 enters the secondary activated carbon injector 9 through the conveying pipeline and is then injected into the adsorption flue 10. Under the action of the baffle 11, the injected secondary activated carbon is fully mixed with the flue gas, forming an enhanced gas-solid contact process. The baffle 11 changes the flow state of the flue gas in the adsorption flue 10, enhances turbulent mixing and mass transfer contact, and prolongs the effective contact time between the activated carbon powder and the pollutants in the flue gas. The secondary activated carbon adsorbs and captures unconventional pollutants such as escaped ammonia, HCl, alkali metals, and VOCs in the denitrification flue gas, realizing the synergistic removal of multiple pollutants under the conditions of deep peak shaving and high proportion of clean fuel blending.

[0034] S4. Flue gas purification and emission: The flue gas treated by the adsorption flue 10 enters the activated carbon separator 14. The activated carbon separator 14 separates the activated carbon enriched with pollutants from the flue gas. The separated flue gas enters the bag filter 16 to remove fly ash, dust and residual activated carbon from the flue gas. Then the flue gas enters the desulfurization tower 17 to further remove SO2 from the flue gas through the desulfurizing agent. Finally, it is discharged through the chimney 18.

[0035] S5. Activated carbon regeneration and reuse: The activated carbon enriched with pollutants obtained by the activated carbon separator 14 enters the activated carbon regeneration device 15 for thermal regeneration treatment, so that NH3, HCl, VOCs and other pollutants adsorbed on the activated carbon are desorbed. The activated carbon that meets the requirements after regeneration is returned to the activated carbon secondary storage silo 8 for recycling through the reuse pipeline. Example

[0036] This embodiment uses the above system and applies it to a deep peak-shaving condition of a coal-fired boiler at 50% rated load. When the coal-fired boiler operates under this deep peak-shaving condition, the flue gas temperature before entering the denitrification tower 2 is 250℃, and the NO content in the flue gas is... x Concentration of 350 mg / Nm 3 The SO2 concentration is 800 mg / Nm³. 3 The HCl concentration was 30 ppm, and the VOCs concentration was 50 mg / Nm³. 3 .

[0037] Before the flue gas enters the denitrification tower 2, the temperature feedback controller 1 monitors the flue gas temperature at the inlet of the denitrification tower 2 in real time and transmits the temperature signal to the dual-stage activated carbon linkage injection controller 13; the multi-pollutant monitoring unit 12 simultaneously monitors the NO in the flue gas at the inlet and outlet of the denitrification tower 2. x and the concentration of escaped NH3. Ammonia injection grid 3 is based on the relationship between NH3 and NO. x NH3 reducing agent is injected into the flue gas at a molar ratio of 1:1. The flue gas then enters the denitrification tower 2 and comes into contact with the vanadium-tungsten-titanium-based catalyst layer 4.

[0038] Because the inlet flue gas temperature of denitrification tower 2 is 250℃, which is lower than the efficient reaction temperature window of conventional vanadium-tungsten-titanium-based catalysts, the activity of vanadium-tungsten-titanium-based catalyst layer 4 decreases, and the NO at the outlet of denitrification tower 2 increases. x As the concentration increases, the escaped NH3 concentration also increases. At this time, the dual-stage activated carbon injection controller 13, based on the low-temperature signal fed back by the temperature feedback controller 1, starts the primary activated carbon injector 7, and, based on the NO concentration at the outlet of the denitrification tower 2... x The concentration change adjusts the amount of primary activated carbon injected.

[0039] In this embodiment, the primary activated carbon is a powdered nitrogen-containing activated carbon with a particle size of 20~60μm and a specific surface area of ​​1200m². 2 / g, with a surface nitrogen content of 4 at.%, and a pore structure dominated by micropores. Primary activated carbon from the primary activated carbon storage silo 6 is injected into the area above the vanadium-tungsten-titanium-based catalyst layer 4 within the denitrification tower 2 via the primary activated carbon injector 7. After being evenly distributed and rectified by the porous distribution plate 5, it is uniformly dispersed and adheres to the surface of the vanadium-tungsten-titanium-based catalyst layer 4. The mass ratio of primary activated carbon to the vanadium-tungsten-titanium-based catalyst layer 4 is controlled at 6:100, forming an activated carbon-vanadium-tungsten-titanium-based catalyst composite denitrification system.

[0040] Under the conditions of this embodiment, after starting the primary activated carbon injection, the NO at the outlet of denitrification tower 2... x The concentration can be reduced to 50 mg / Nm 3 Below this, the escaped NH3 concentration can be reduced to below 5 ppm, NO xThe removal rate can be increased to over 80%. The flue gas after denitrification treatment enters the adsorption flue duct 10 and activated carbon separator 14, then sequentially enters the bag filter 16, desulfurization tower 17, and chimney 18, achieving NO removal under 50% rated load deep peak shaving conditions. x Stable control of escaped NH3, particulate matter and SO2. Example

[0041] This embodiment uses the aforementioned system for flue gas purification in a coal-fired boiler operating under a 50% co-firing condition of straw-based biomass. The biomass is rice straw, and the biomass co-firing ratio is 50% of the fuel input.

[0042] In this embodiment, the flue gas temperature before entering the denitrification tower 2 is 320°C, and the NO content is... x The concentration is 450 mg / Nm 3 The SO2 concentration is 600 mg / Nm³. 3 The HCl concentration was 100 ppm, and the VOCs concentration was 120 mg / Nm³. 3 It also contains alkali metal pollutants such as sodium, potassium and their oxides, chlorides or sulfates aerosols.

[0043] Before the flue gas enters the denitrification tower 2, the temperature feedback controller 1 monitors the flue gas temperature in real time, and the multi-pollutant monitoring unit 12 monitors the NO at the inlet of the denitrification tower 2, the outlet of the denitrification tower 2, and the outlet of the adsorption flue duct 10. x The concentrations of NH3, HCl, and VOCs, as well as the flue gas flow rate, are monitored online, and the monitoring signals are transmitted to the two-stage activated carbon linkage injection controller 13. The ammonia injection grid 3 operates according to the concentrations of NH3 and NO... x NH3 reducing agent is injected into the flue gas at a molar ratio of 1:1, causing the flue gas to undergo NH3-SCR denitrification reaction on the surface of vanadium-tungsten-titanium-based catalyst layer 4.

[0044] The flue gas treated by the denitrification tower 2 enters the adsorption flue 10. Due to the increased concentration of unconventional pollutants such as NH3, HCl, alkali metals, and VOCs in the flue gas after the co-combustion of 50% straw biomass, the dual-stage activated carbon linkage injection controller 13 starts and increases the injection rate of the secondary activated carbon injector 9 based on the pollutant concentration signal fed back by the multi-pollutant monitoring unit 12. The secondary activated carbon in the secondary activated carbon storage silo 8 is injected into the adsorption flue 10 through the secondary activated carbon injector 9 and is fully mixed with the flue gas under the action of the baffle 11. The injection rate of the secondary activated carbon is 0.10 g / Nm³. 3 Smoke.

[0045] In this embodiment, the secondary activated carbon is a powdered, hierarchical porous activated carbon with a particle size of 30-80 μm and a specific surface area of ​​700 m². 2 / g, total pore volume is 0.6cm³ 3 / g, with mesopores and macropores accounting for 40% of the total pore volume. The surface of the secondary activated carbon contains oxygen-containing functional groups and nitrogen-containing functional groups, with an oxygen content of 5 at.% and a nitrogen content of 3 at.%; the oxygen-containing functional groups include hydroxyl, carboxyl, carbonyl and ether bonds, and the nitrogen-containing functional groups include pyridine nitrogen, pyrrole nitrogen and graphitic nitrogen.

[0046] Secondary activated carbon utilizes micropores to provide pollutant adsorption capacity, mesopores and macropores to provide rapid mass transfer channels, and regulates surface polarity, acidity and alkalinity and adsorption activity through oxygen-containing and nitrogen-containing functional groups on the surface, thereby synergistically adsorbing and capturing unconventional pollutants such as escaping NH3, HCl, alkali metals and VOCs.

[0047] Under the conditions of this embodiment, after starting the secondary activated carbon injection, the NH3 concentration at the outlet of adsorption flue 10 can be reduced to below 5 ppm, the HCl concentration can be reduced to below 10 ppm, and the VOCs concentration can be reduced to 20 mg / Nm³. 3 The removal rates of NH3, HCl and VOCs reached 70%, 80% and above, respectively.

[0048] After adsorbing pollutants, the secondary activated carbon enters the activated carbon separator 14 with the flue gas. The activated carbon separator 14 separates the pollutant-enriched activated carbon from the flue gas. The separated flue gas enters the bag filter 16 to further capture fly ash, dust and residual activated carbon. Then the flue gas enters the desulfurization tower 17, where SO2 is further removed by the desulfurizing agent. The SO2 removal rate can reach more than 90%. Finally, the purified flue gas is discharged through the chimney 18.

[0049] The activated carbon enriched with pollutants, separated by the activated carbon separator 14, enters the activated carbon regeneration device 15 for thermal regeneration treatment. The regeneration temperature is 300℃, the regeneration atmosphere is nitrogen, and the regeneration time is 120 minutes. After regeneration, the activated carbon that meets the requirements for specific surface area retention rate and pollutant adsorption capacity is returned to the activated carbon secondary storage silo 8 for recycling via the reuse pipeline.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A two-stage activated carbon multi-pollutant control system for clean fuel co-firing and deep peak shaving, comprising a denitrification tower, an ammonia injection grid, a vanadium-tungsten-titanium-based catalyst layer, a bag filter, a desulfurization tower, and a chimney, wherein the ammonia injection grid is located at the inlet of the denitrification tower and connected to an external ammonia supply pipeline, and the vanadium-tungsten-titanium-based catalyst layer adopts a multi-layer structure and is spaced axially inside the denitrification tower, characterized in that... It also includes a temperature feedback controller, a primary activated carbon storage bin, a primary activated carbon injector, a porous uniform distribution plate, an adsorption flue, a secondary activated carbon storage bin, a secondary activated carbon injector, a baffle plate, a multi-pollutant monitoring unit, a dual-stage activated carbon linkage injection controller, an activated carbon separator, and an activated carbon regeneration device. The temperature feedback controller is set at the flue gas duct before the inlet of the denitrification tower to monitor the flue gas temperature in real time and provide feedback signals; the porous uniformly distributed plate is set in the interval area of ​​the vanadium-tungsten-titanium-based catalyst layer; the activated carbon primary storage silo is connected to the activated carbon primary injector through a conveying pipeline; the activated carbon primary injector is set on the side of the denitrification tower and communicates with the porous uniformly distributed plate inside the denitrification tower. The outlet of the denitrification tower is connected to the inlet of the adsorption flue. The activated carbon secondary storage silo is connected to the activated carbon secondary injector through a conveying pipeline. The activated carbon secondary injector is installed on the adsorption flue and is connected to the inside of the adsorption flue. The baffle is installed inside the adsorption flue and is located in the adjacent area of ​​the activated carbon secondary injector. The outlet of the adsorption flue is connected to the inlet of the activated carbon separator, the solid outlet of the activated carbon separator is connected to the activated carbon regeneration device, the outlet of the activated carbon regeneration device is connected to the activated carbon secondary storage silo through a reuse pipeline, the flue gas outlet of the activated carbon separator is connected to the inlet of the bag filter, the outlet of the bag filter is connected to the inlet of the desulfurization tower, and the outlet of the desulfurization tower is connected to the chimney. The multi-pollutant monitoring unit is connected to the inlet flue of the denitrification tower, the outlet flue of the denitrification tower, and the outlet flue of the adsorption flue, respectively. The dual-stage activated carbon linkage injection controller is connected to the temperature feedback controller, the first-stage activated carbon injector, the second-stage activated carbon injector, and the multi-pollutant monitoring unit, respectively, and dynamically adjusts the injection volume of the two-stage activated carbon according to the flue gas temperature and pollutant concentration.

2. The dual-stage activated carbon multi-pollutant control system under clean fuel co-firing and deep peak shaving as described in claim 1, characterized in that: The first-stage activated carbon sprayed by the first-stage activated carbon injector is in a powder or granular form, has a particle size of 10-100 μm, a specific surface area of 1000-1700 m 2 / g, a pore structure of micropore, a surface containing nitrogen-containing functional groups with a nitrogen content of 1-8 at.%, the nitrogen-containing functional groups including one or more of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen, and a mass ratio of the first-stage activated carbon to the vanadium-tungsten-titanium-based catalyst layer of 1:100-10:

100.

3. The dual-stage activated carbon multi-pollutant control system for clean fuel blending and deep peak shaving as described in claim 1, characterized in that: The secondary activated carbon sprayed by the secondary activated carbon injector is in powder form, with a particle size of 10~100μm and a specific surface area of ​​500~1000m². 2 / g, total pore volume is 0.3~1.0cm³ 3 / g; the secondary activated carbon has a hierarchical pore structure, including micropores, mesopores and macropores, of which the pore volume of mesopores and macropores accounts for 20% to 60% of the total pore volume; the surface of the secondary activated carbon contains oxygen-containing functional groups and / or nitrogen-containing functional groups, with an oxygen content of 5 to 10 at.% and a nitrogen content of 2 to 10 at.%.

4. The dual-stage activated carbon multi-pollutant control system for clean fuel blending and deep peak shaving as described in claim 1, characterized in that: The activated carbon separator is a cyclone separator, an inertial separator, a ceramic filter separator, or a combination thereof, with a separation efficiency of 80% to 99% for activated carbon; the activated carbon regeneration device adopts a thermal regeneration method, with a regeneration temperature of 150 to 300°C, a regeneration atmosphere of nitrogen, water vapor, or a mixture thereof, and a regeneration time of 10 to 120 minutes.

5. The dual-stage activated carbon multi-pollutant control system for clean fuel blending and deep peak shaving as described in claim 1, characterized in that: The control logic of the dual-stage activated carbon linkage injection controller is as follows: when the flue gas temperature at the inlet of the denitrification tower is below 300℃, the primary activated carbon injector is activated; when the NH3 concentration at the outlet of the denitrification tower is above 3~5ppm, the HCl concentration is above 10ppm, or the VOCs concentration is above 20mg / Nm³, the primary activated carbon injector is activated. 3 When the pollutant concentration is below the set value, the secondary activated carbon injector is activated; when the pollutant concentration is below the set value, the corresponding activated carbon injection rate is reduced.

6. A method for controlling multiple pollutants using two-stage activated carbon under clean fuel blending and deep peak shaving, characterized in that: The control method of the dual-stage activated carbon multi-pollutant control system under clean fuel blending and deep peak shaving as described in claim 1 includes the following steps: S1. Real-time Operating Condition Monitoring: Before the flue gas from the coal-fired boiler enters the denitrification tower, the flue gas temperature is monitored in real time by a temperature feedback controller and fed back to the two-stage activated carbon linkage injection controller; simultaneously, the NO2 concentration in the inlet flue, outlet flue, and adsorption flue outlet flue of the denitrification tower is monitored by a multi-pollutant monitoring unit. x The concentrations of NH3, HCl, and VOCs, as well as the flue gas flow rate, are monitored online, and the monitoring signals are transmitted to the two-stage activated carbon linkage injection controller to determine the current operating condition of the system. S2. Staged Denitrification Reaction: When the flue gas temperature at the inlet of the denitrification tower is detected to be 300~400℃, NH3 reducing agent is injected into the flue gas entering the denitrification tower through the ammonia injection grid, reducing the NO in the flue gas. x NO undergoes a selective catalytic reduction reaction with NH3 on the surface of the vanadium-tungsten-titanium-based catalyst layer, achieving NO under rated operating conditions. x Removal; When the flue gas temperature is detected to be below 300℃, the dual-stage activated carbon linkage injection controller activates the primary activated carbon injector. The primary activated carbon is uniformly distributed and rectified by a porous uniform distribution plate and then uniformly adheres to the surface of the vanadium-tungsten-titanium-based catalyst layer, forming an activated carbon-vanadium-tungsten-titanium-based catalyst composite denitrification system, which enhances NO removal under low-temperature conditions. x Remove; S3, Secondary Synergistic Adsorption: When an increase in the concentration of NH3, HCl or VOCs at the outlet of the denitrification tower is detected, or when the demand for removal of unconventional pollutants increases, the dual-stage activated carbon linkage injection controller starts the secondary activated carbon injector to inject secondary activated carbon into the adsorption flue. Under the action of the baffle, the secondary activated carbon is fully turbulently mixed with the flue gas to adsorb and capture escaped ammonia, HCl, alkali metals and VOCs in the denitrification flue gas. S4. Flue gas purification and emission: After being treated by the adsorption flue, the flue gas enters the activated carbon separator to complete gas-solid separation. The separated flue gas first enters the bag filter to remove residual particulate matter, then enters the desulfurization tower to remove SO2, and finally is emitted through the chimney. S5. Activated carbon regeneration and reuse: The activated carbon enriched with pollutants obtained by the activated carbon separator is sent to the activated carbon regeneration device for thermal regeneration treatment. The activated carbon that meets the performance standards after regeneration is returned to the secondary activated carbon storage silo for recycling.

7. The method for controlling multiple pollutants with dual-stage activated carbon under clean fuel blending and deep peak shaving as described in claim 6, characterized in that: In step S2, the ammonia injection grid controls the mixing of NH3 and NO. x The molar ratio is 0.8~1.2, and the mass ratio of primary activated carbon to vanadium-tungsten-titanium-based catalyst layer is 1:100~10:

100.

8. The method for controlling multiple pollutants with dual-stage activated carbon under clean fuel blending and deep peak shaving as described in claim 6, characterized in that: In step S5, when the specific surface area retention rate of the regenerated activated carbon is less than 70%, or the adsorption capacity of pollutants is less than 60% of that of the fresh activated carbon, the portion of activated carbon is discharged from the system and fresh activated carbon is added.

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