A flue gas denitrification and CO removal system
By placing the CO removal reaction zone after the CO removal reaction zone in the flue gas denitrification and CO removal system, and combining it with an intelligent control system, the impact of NOx and SO2 on the catalyst is solved, achieving efficient pollutant removal and energy saving.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- YIZHONG GRP DALIAN ENG CONSTR CO LTD
- Filing Date
- 2025-07-30
- Publication Date
- 2026-07-03
AI Technical Summary
In existing flue gas combined denitrification and deCO removal technologies, it is difficult to effectively avoid the corrosive effects of NOx on the deCO removal catalyst and the impact of SO2 generated from the combustion of supplementary fuel on the catalyst activity and lifespan, leading to a decline in catalyst performance and an increase in energy consumption.
The CO removal reaction zone is set after the denitrification reaction zone, and the heat replenishment system is located after the CO removal reaction zone. The method of denitrification first and then CO removal is adopted, and heat recovery is achieved through gas-to-gas heat exchanger. Combined with intelligent control system, the flue gas temperature is adjusted to avoid the impact of NOx and SO2 on the catalyst.
This approach achieves reduced energy consumption while ensuring catalyst activity and lifespan, resulting in highly efficient pollutant removal, and ensures emissions meet standards through temperature control.
Smart Images
Figure CN224442609U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of industrial furnace flue gas treatment engineering technology, specifically relating to a flue gas denitrification and CO removal system. Background Technology
[0002] Flue gas desulfurization followed by denitrification technology has been widely applied and developed in industries such as steel, metallurgy, and power. Because the SO2 content in the desulfurized flue gas is very low, the service life of the denitrification catalyst is greatly extended. However, a drawback is the low temperature of the desulfurized flue gas, which requires heating to reach the temperature needed for denitrification. Heating the flue gas requires a large amount of heat, and even with the use of gas-to-gas heat exchangers (GGH) to recover some heat, a significant amount of additional fuel is still consumed to raise the flue gas temperature to the range required for denitrification.
[0003] Due to insufficient fuel production and other reasons, flue gas contains a large amount of CO, which not only wastes fuel but also pollutes the environment. Therefore, CO removal from flue gas has received increasing attention in recent years. CO removal generally employs catalytic oxidation technology. The exothermic reaction of catalytic oxidation raises the temperature of the flue gas, and combining it with denitrification can save some of the fuel needed to raise the flue gas temperature. In recent years, combined flue gas denitrification and CO removal technologies have been extensively researched and developed.
[0004] There are generally two configuration methods for combined denitrification and CO removal technology:
[0005] One configuration places the CO removal reactor before the denitrification reactor, with a supplementary heating device located before or after the CO removal reactor. This combined CO catalytic oxidation and supplementary heating raises the flue gas temperature to the range required for denitrification. This method has the following main drawbacks: First, since the flue gas has not undergone denitrification, the NOx in the flue gas is corrosive to the CO oxidation catalyst, affecting its activity and lifespan. Second, during the flue gas supplementary heating process, the combustion of SO2 from the fuel (containing sulfur) reduces the catalyst's activity and lifespan, whether it enters the CO removal reactor or the denitrification reactor, especially when the supplementary heating gas is unevenly mixed with the flue gas. Third, when the supplementary heating device is located after the CO removal reactor, the CO removal reactor relies on the flue gas's own temperature, which is relatively low, making it difficult to achieve a high CO conversion rate, or requiring a catalyst with a high content of precious metals, significantly increasing costs.
[0006] Another configuration is to place the CO removal reactor after the denitrification reactor, and the reheating device is located before the denitrification reactor, or after the denitrification reactor and before the CO removal reactor. This configuration reduces the impact of NOx on the activity and lifespan of the CO removal catalyst, but does not reduce the impact of SO2 generated during the reheating process on the activity and lifespan of the denitrification or CO removal catalyst. Utility Model Content
[0007] To overcome the problems existing in the prior art, this utility model provides a flue gas denitrification and CO removal system. The CO removal reaction zone is set after the denitrification reaction zone, and the method of denitrification before CO removal is adopted to avoid the impact of NOx on the activity and lifespan of the CO removal catalyst. The heat replenishment system is set after the CO removal reaction zone to avoid the impact of SO2 generated by the combustion of the heat replenishment fuel on the activity and lifespan of the CO removal catalyst. The heat replenishment flue gas is mixed with the high-temperature flue gas after CO removal and then undergoes efficient heat exchange with the low-temperature desulfurization flue gas through a gas-to-gas heat exchanger to increase the temperature of the flue gas before denitrification.
[0008] The technical solution adopted by this utility model to solve its technical problem is:
[0009] A flue gas denitrification and CO removal system includes: a gas-gas heat exchanger, an ammonia mixer, a denitrification reaction zone equipped with a denitrification catalyst, a CO removal reaction zone equipped with a CO removal catalyst, and a heat replenishment system.
[0010] The desulfurized flue gas is fed into the low-temperature side inlet of the gas-to-gas heat exchanger through a flue.
[0011] The low-temperature side outlet of the gas-gas heat exchanger is connected to the downstream denitrification reaction zone through a flue, and an ammonia mixer is installed on the connecting flue, which is connected to an external ammonia-air mixed gas source.
[0012] The denitrification reaction zone is connected downstream to the CO removal reaction zone;
[0013] The outlet of the CO removal reaction zone is connected to the high-temperature side inlet of the gas-gas heat exchanger via a flue, and a flue gas mixer is provided on the connecting flue.
[0014] The high-temperature flue gas outlet of the heat replenishment system is connected to the flue between the CO removal reaction zone and the gas-to-gas heat exchanger, and the connection point is located upstream of the flue gas mixer.
[0015] The high-temperature side outlet of the gas-gas heat exchanger is connected to the inlet of the induced draft fan via a flue, and the outlet of the induced draft fan is connected to the chimney via a flue.
[0016] Furthermore, the denitrification reaction zone and the deCO reaction zone are arranged in a split structure: the denitrification catalyst is located in the denitrification reactor, the deCO catalyst is located in the deCO reactor, and the denitrification reactor and the deCO reactor are independent of each other and connected by a flue.
[0017] Furthermore, the denitrification reaction zone and the CO removal reaction zone are arranged in an integrated structure: the denitrification catalyst and the CO removal catalyst are integrated and set in the same reactor shell and arranged sequentially along the flue gas flow direction.
[0018] Furthermore, the heat replenishment system includes a combustion device, a gas pipeline, a combustion fan, and a combustion air pipeline; the gas pipeline is connected to the inlet of the combustion device and is equipped with a gas flow meter and a gas regulating valve; the combustion air pipeline is connected to the inlet of the combustion device via the combustion fan and is equipped with a combustion air flow meter and a combustion air regulating valve; the outlet of the combustion device is connected to the flue between the CO removal reaction zone and the gas-to-gas heat exchanger.
[0019] Furthermore, the combustion device is a separate hot air furnace or a flue burner directly installed in the flue.
[0020] Furthermore, the connecting flue between the gas-to-gas heat exchanger and the denitrification reaction zone is respectively equipped with:
[0021] The first concentration analyzer is used to monitor the CO concentration in desulfurization flue gas.
[0022] The second concentration analyzer is used to monitor the NOx concentration in desulfurization flue gas.
[0023] A temperature sensor is used to monitor the temperature of flue gas before denitrification.
[0024] Furthermore, the connecting flue between the induced draft fan and the chimney is equipped with:
[0025] The third concentration analyzer is used to monitor the CO concentration in the purified flue gas.
[0026] The fourth concentration analyzer is used to monitor the NOx concentration in the purified flue gas.
[0027] Furthermore, it also includes a controller, which is electrically connected to the third concentration analyzer, the fourth concentration analyzer, the first concentration analyzer, the second concentration analyzer, the temperature sensor, the gas flow meter, the gas regulating valve, the combustion air flow meter, and the combustion air regulating valve, respectively.
[0028] The beneficial effects of this utility model include:
[0029] By placing the CO removal reaction zone after the NOx removal reaction zone, the corrosive effect of NOx on the CO removal catalyst is avoided. Simultaneously, placing the supplementary heating system after the CO removal reaction zone prevents the SO2 generated from the combustion of supplementary heating fuel from affecting the performance and lifespan of the NOx or CO removal catalyst. The system utilizes the mixing of the high-temperature flue gas after the CO removal reaction with the supplementary heating flue gas in a mixer, and achieves heat recovery and utilization through a gas-to-gas heat exchanger, thereby increasing the temperature of the flue gas before NOx removal. This ensures the operating temperature of the CO removal reaction while reducing system energy consumption. Compared to traditional processes, this method reduces energy consumption while ensuring pollutant emissions meet standards, and good removal efficiency can be achieved using conventional catalysts.
[0030] By setting the controller, third concentration analyzer, fourth concentration analyzer, first concentration analyzer, second concentration analyzer, temperature sensor, gas flow meter, gas regulating valve, combustion air flow meter, and combustion air regulating valve, the setpoint for flue gas temperature control before the denitrification reaction can be adjusted according to the NOx and CO content in the exhaust gas. The flue gas temperature before the denitrification reaction can be controlled by controlling the gas flow of the supplementary heating system. In other words, the set temperature before denitrification changes with the CO and NOx concentrations of the purified flue gas, ensuring that the CO and NOx concentrations of the flue gas meet emission standards and saving supplementary heating energy. Attached Figure Description
[0031] Figure 1 This is a structural diagram of a flue gas denitrification and CO removal system (reactor is set up separately);
[0032] Figure 2 This is a structural diagram of a flue gas denitrification and CO removal system (the reactors share a common shell).
[0033] In the diagram: 1-Gas-to-gas heat exchanger, 2-First concentration analyzer, 3-Second concentration analyzer, 4-Temperature sensor, 5-Ammonia mixer, 6-Denitrification reactor, 7-Denitrification catalyst, 8-DeCO reactor, 9-DeCO catalyst, 10-Flue gas mixer, 11-Induced draft fan, 12-Combustion fan, 13-Chimney, 14-Third concentration analyzer, 15-Fourth concentration analyzer, 16-Gas regulating valve, 17-Combustion air regulating valve, 18-Combustion device, 19-Controller, 20-Gas flow meter, 21-Combustion air flow meter. Detailed Implementation
[0034] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.
[0035] In the description of this utility model, it should be noted that the terms "first," "second," "third," etc., are used only to distinguish components and should not be construed as indicating or implying relative importance. Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.
[0036] Example 1: Reference Figure 1 A flue gas denitrification and CO removal system includes: a gas-gas heat exchanger 1, an ammonia mixer 5, a denitrification reactor 6, a CO removal reactor 8, a combustion fan 12, and a combustion device 18.
[0037] The desulfurized flue gas enters the gas-gas heat exchanger 1 through the flue from the low-temperature side inlet of the gas-gas heat exchanger 1, and exchanges heat with the purified high-temperature flue gas to recover heat.
[0038] The low-temperature side outlet of the gas-gas heat exchanger 1 is connected to the downstream denitrification reactor 6 through a flue, and an ammonia mixer 5 is provided on the flue. The ammonia mixer 5 is connected to an external ammonia-air mixed gas source. The ammonia-air mixed gas is mixed evenly with the desulfurized flue gas after heat exchange through the ammonia mixer 5 to provide the reducing agent required for the denitrification reaction.
[0039] The denitrification reactor 6 is equipped with at least one layer of denitrification catalyst 7. In the denitrification reactor 6, NOx in the flue gas reacts with ammonia and is removed.
[0040] The outlet of the denitrification reactor 6 is connected to the inlet of the downstream deCO reactor 8 through a flue. The deCO reactor 8 is equipped with 1 to 2 layers of deCO catalyst 9. The denitrified flue gas removes CO from the flue gas through a catalytic oxidation reaction in the deCO reactor 8.
[0041] The outlet of the CO removal reactor 8 is connected to the high-temperature side inlet of the gas-to-gas heat exchanger 1 via a flue. The outlet of the combustion device 18 is connected to the connecting flue between the CO removal reactor 8 and the gas-to-gas heat exchanger 1. A flue gas mixer 10 is installed before entering the high-temperature side inlet of the gas-to-gas heat exchanger 1. The flue gas whose temperature rises due to the exothermic reaction after the CO removal reaction is mixed with the high-temperature gas generated by the combustion device 18 in this flue. After being uniformly mixed by the flue gas mixer 10, it enters the gas-to-gas heat exchanger 1 to exchange heat with the desulfurized flue gas, thereby raising the temperature of the flue gas before denitrification and ensuring the working temperature of the denitrification and CO removal reaction.
[0042] The inlet of the combustion device 18 is connected to a gas pipeline for introducing gas into the combustion device 18. The gas can be blast furnace gas, converter gas, natural gas, coke oven gas, or other similar gases. The inlet of the combustion device 18 is also connected to a combustion air pipeline via a combustion air fan 12 for introducing combustion air into the combustion device 18. The aforementioned combustion device 18 can be a separate hot blast stove or a flue gas burner directly installed in the flue.
[0043] The high-temperature side outlet of the gas-gas heat exchanger 1 is connected to the inlet of the induced draft fan 11 through a flue, and the outlet of the induced draft fan 11 is connected to the inlet of the chimney 13 through a flue. The flue gas after purification and heat recovery is discharged through the chimney 13.
[0044] Example 2: Reference Figure 2 In this embodiment, a separate CO removal reactor is not set up. The denitrification catalyst 7 and the CO removal catalyst 9 are placed in the same reactor shell, with the CO removal catalyst 9 placed at the bottom layer of the denitrification reactor 6. This method is mainly suitable for new projects. In this embodiment, the denitrification catalyst 7 is used in two layers, and the CO removal catalyst 9 is used in one layer. The rest is the same as in Example 1.
[0045] Example 3: Existing combined denitrification and CO removal technologies use a constant temperature control method for reaction temperature control, meaning the temperature setpoint before the reactor is a fixed value and does not change with variations in flue gas system parameters. The problem with this is that the reaction temperature cannot adjust to changes in CO and NOx concentrations in the flue gas. When outlet CO and NOx levels are very low, the energy required for supplemental heating cannot be saved by lowering the reaction temperature. Conversely, when outlet CO and NOx concentrations increase, the reaction temperature cannot be raised in a timely manner, potentially leading to emissions exceeding standards.
[0046] Based on the above problems, this embodiment, on the basis of embodiment 1 or 2, is configured with an intelligent control system, including a controller 19, a third concentration analyzer 14, a fourth concentration analyzer 15, a first concentration analyzer 2, a second concentration analyzer 3, a temperature detector 4, a gas flow detector 20, a gas regulating valve 16, a combustion air flow detector 21, and a combustion air regulating valve 17.
[0047] The controller 19 is an existing controller with signal receiving, processing and sending functions, including but not limited to PLC, DCS and other intelligent control instruments.
[0048] refer to Figure 1 or Figure 2 The gas pipeline is equipped with a gas flow meter 20 and a gas regulating valve 16; the combustion air pipeline is equipped with a combustion air flow meter 21 and a combustion air regulating valve 17.
[0049] The gas-to-gas heat exchanger 1 and the denitrification reaction zone are connected by a first concentration analyzer 2, a second concentration analyzer 3, and a temperature sensor 4. The first concentration analyzer 2 is used to monitor the CO concentration in the desulfurization flue gas; the second concentration analyzer 3 is used to monitor the NOx concentration in the desulfurization flue gas; and the temperature sensor 4 is used to monitor the temperature of the flue gas before denitrification.
[0050] A third concentration analyzer 14 and a fourth concentration analyzer 15 are respectively installed on the connecting flue between the induced draft fan 11 and the chimney 13; the third concentration analyzer 14 is used to monitor the CO concentration of the purified flue gas; the fourth concentration analyzer 15 is used to monitor the NOx concentration of the purified flue gas.
[0051] The controller 19 is electrically connected to the third concentration analyzer 14, the fourth concentration analyzer 15, the first concentration analyzer 2, the second concentration analyzer 3, the temperature detector 4, the gas flow meter 20, the gas regulating valve 16, the combustion air flow meter 21, and the combustion air regulating valve 17, respectively.
[0052] Based on the above-mentioned intelligent control system structure, its control flow is as follows: A combination of a cascade control system and a proportional control system is used to control the flue gas denitrification and CO removal system. The cascade control system uses the CO concentration measured by the third concentration analyzer 14 (purified flue gas CO concentration analyzer) and the NOx concentration measured by the fourth concentration analyzer 15 (purified flue gas NOx concentration analyzer) as the main control variables, and the flue gas temperature before denitrification as the secondary control variable. The main control loop inputs the measured purified flue gas CO concentration and purified flue gas NOx concentration into the controller 19. The output of the controller 19 after logic calculation is used as the setpoint for controlling the flue gas temperature before denitrification. The secondary control loop adjusts the gas flow rate by adjusting the opening of the supplementary heating system gas regulating valve 16 according to the difference between the measured value and the setpoint of the flue gas temperature before denitrification through the controller 19.
[0053] The gas flow rate and the combustion air flow rate are controlled proportionally.
[0054] The logical calculations for the CO and NOx concentrations in the purified flue gas are as follows: when either the measured CO or NOx concentration exceeds the set range, the pre-denitrification flue gas temperature setpoint increases; when both are within the set range, the pre-denitrification flue gas temperature setpoint remains unchanged; and when both are below the set range, the pre-denitrification flue gas temperature setpoint decreases.
[0055] Preferably, to avoid frequent fluctuations, when adjusting the flue gas temperature setting before denitrification, the temperature increase or decrease should be limited to 2-10°C each time, and the next judgment and adjustment should be performed only after a delay of 30-120 minutes after each adjustment.
[0056] Example 4: This invention is illustrated using specific numerical values. It should be noted that the temperature, concentration, and other numerical values listed in this example are only for illustrating the principle of this invention and do not represent definitive numerical values protected by this patent.
[0057] refer to Figure 1 As shown, the denitrification reactor 6 and the deCO reactor 8 are set up separately, which is mainly suitable for retrofit projects that add a deCO reactor to an existing denitrification unit.
[0058] Taking activated coke desulfurization flue gas as an example, the flue gas from desulfurization is about 120°C and has a CO content of about 5000 mg / m³. 3 NOx content is approximately 300 mg / m³ 3 Environmental emission requirements stipulate a CO content of approximately 200 mg / m³. 3 NOx content is approximately 50 mg / m³ 3 .
[0059] The desulfurized flue gas enters the gas-gas heat exchanger 1 through the low-temperature side inlet. After exchanging heat with the purified high-temperature flue gas, its temperature rises to the initial design temperature (280℃, depending on the catalyst). An ammonia-air mixture is then introduced and thoroughly mixed in the ammonia-air mixer 5 before entering the denitrification reactor 6. The denitrification reactor 6 is equipped with at least one layer of denitrification catalyst 7. Figure 1 The diagram shows three layers. In the denitrification reactor 6, NOx is removed by an SCR reaction with ammonia. The denitrified flue gas then enters the CO removal reactor 8, which is equipped with at least one layer of CO removal catalyst 9. Figure 1 The diagram shows layer 1. In the CO removal reactor 8, CO is removed by catalytic oxidation to produce CO2 under the action of a catalyst. After denitrification and CO removal, the temperature of the flue gas rises by 30°C to approximately 310°C due to the exothermic reaction.
[0060] The reheating system uses blast furnace gas as fuel, and the combustion device 18 uses a hot blast stove. The gas regulating valve 16 is adjusted, and the combustion air regulating valve 17 is controlled simultaneously, so that the flow rates measured by the combustion air flow meter 21 and the gas flow meter 20 change in a certain proportion, which is determined by the composition of the blast furnace gas. This ensures that the temperature measured by the pre-denitrification flue gas temperature meter 4 is close to the initial design value of 280℃. The purified flue gas after reheating enters the gas-gas heat exchanger 1 from the high-temperature side inlet, exchanges heat with the low-temperature desulfurization flue gas, and is then sent to the chimney 13 by the induced draft fan 11 for discharge.
[0061] The intelligent control system uses PLC control.
[0062] The flue gas denitrification and CO removal system employs a cascade control system, using the concentrations of CO and NOx in the purified flue gas detected by the third concentration analyzer 14 (purified flue gas CO concentration analyzer) and the fourth concentration analyzer 15 (purified flue gas NOx concentration analyzer) as the main control parameters. Based on emission requirements, the control range for CO and NOx concentrations in the purified flue gas is selected to be slightly lower than the emission standard requirements. In this embodiment, the CO concentration control range is 100–180 mg / m³. 3 The concentration control range for NOx is 20–40 mg / m³. 3 When either the CO or NOx concentration exceeds the control range, the pre-denitrification flue gas temperature control setpoint is increased by 5°C; when both concentrations are within the control range, the pre-denitrification flue gas temperature control setpoint remains unchanged; when both concentrations are below the control range, the pre-denitrification flue gas temperature control setpoint is decreased by 5°C. To prevent frequent fluctuations, a 30-minute delay is allowed after each setting adjustment before the next judgment and adjustment can be performed.
[0063] The secondary loop of the cascade control system consists of a temperature sensor 4 for the pre-denitrification flue gas and a supplementary heating system. When the pre-denitrification flue gas temperature is higher than the design value, the gas regulating valve 16 closes slightly; when the pre-denitrification flue gas temperature is lower than the design value, the gas regulating valve 16 opens wider. At this time, the value detected by the gas flow meter 20 changes accordingly, adjusting the combustion air regulating valve 17 so that the ratio of the air flow rate detected by the combustion air flow meter 21 to the gas flow rate is constant.
[0064] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A flue gas denitrification and CO removal system, characterized in that, include: Gas-to-gas heat exchanger (1), ammonia mixer (5), denitrification reaction zone equipped with denitrification catalyst (7), deCO reaction zone equipped with deCO catalyst (9), and heat replenishment system; The desulfurized flue gas is fed into the low-temperature side inlet of the gas-to-gas heat exchanger (1) through the flue; The low-temperature side outlet of the gas-gas heat exchanger (1) is connected to the downstream denitrification reaction zone through a flue, and an ammonia mixer (5) is provided on the flue, which is connected to an external ammonia-air mixed gas source. The denitrification reaction zone is connected downstream to the CO removal reaction zone; The outlet of the CO removal reaction zone is connected to the high-temperature side inlet of the gas-gas heat exchanger (1) through a flue, and a flue gas mixer (10) is provided on the flue. The high-temperature flue gas outlet of the heating system is connected to the flue between the CO removal reaction zone and the gas-to-gas heat exchanger (1), and the connection point is located upstream of the flue gas mixer (10). The high-temperature side outlet of the gas-gas heat exchanger (1) is connected to the inlet of the induced draft fan (11) through a flue, and the outlet of the induced draft fan (11) is connected to the chimney (13) through a flue.
2. The flue gas denitration and CO removal system according to claim 1, characterized in that, The denitrification reaction zone and the deCO reaction zone are arranged in a split structure: the denitrification catalyst (7) is located in the denitrification reactor (6), and the deCO catalyst (9) is located in the deCO reactor (8). The denitrification reactor (6) and the deCO reactor (8) are independent of each other and connected by a flue.
3. The flue gas denitration and CO removal system according to claim 1, characterized in that, The denitrification reaction zone and the deCO reaction zone are arranged in an integrated structure: the denitrification catalyst (7) and the deCO catalyst (9) are integrated in the same reactor shell and arranged sequentially along the flue gas flow direction.
4. The flue gas denitration and CO removal system according to claim 1, characterized in that, The heating system includes a combustion device (18), a gas pipeline, a combustion fan (12), and a combustion air pipeline; the gas pipeline is connected to the inlet of the combustion device (18), and a gas flow meter (20) and a gas regulating valve (16) are provided on the gas pipeline; the combustion air pipeline is connected to the inlet of the combustion device (18) through the combustion fan (12), and a combustion air flow meter (21) and a combustion air regulating valve (17) are provided on the combustion air pipeline; the outlet of the combustion device (18) is connected to the flue between the CO removal reaction zone and the gas-to-gas heat exchanger (1).
5. The flue gas denitration and CO removal system according to claim 4, characterized in that, The combustion device (18) is a separate hot air furnace or a flue burner directly installed in the flue.
6. The flue gas denitration and CO removal system according to claim 4, characterized in that, The gas-to-gas heat exchanger (1) and the denitrification reaction zone are respectively equipped with: The first concentration analyzer (2) is used to monitor the CO concentration in the desulfurization flue gas; The second concentration analyzer (3) is used to monitor the NOx concentration in the desulfurization flue gas; Temperature sensor (4) is used to monitor the temperature of flue gas before denitrification.
7. The flue gas denitration and CO removal system according to claim 6, characterized in that, The connecting flue between the induced draft fan (11) and the chimney (13) is respectively equipped with: The third concentration analyzer (14) is used to monitor the CO concentration of the purified flue gas; The fourth concentration analyzer (15) is used to monitor the NOx concentration in the purified flue gas.
8. The flue gas denitration and CO removal system according to claim 7, characterized in that, Also included is a controller (19) electrically connected with the third concentration analyzer (14), the fourth concentration analyzer (15), the first concentration analyzer (2), the second concentration analyzer (3), the temperature detector (4), the gas flow detector (20), the gas regulating valve (16), the combustion air flow detector (21), and the combustion air regulating valve (17), respectively.