Ultra-low emission burner assembly

Abstract

The utility model relates to the field of gasification of granular or powdery fuel in a suspension state, in particular to an ultra-low emission burner assembly. The ultralow-emission burner assembly comprises a heating furnace (1), burners (2), flue gas branch pipes (31) and a flue gas main pipe (32), and is characterized by further comprising a front gas detector (41), a rear gas detector (42), a reduction catalyst chamber (51), an oxygenation chamber (52), an oxidation catalyst chamber (53), controllable burners (6), a front controller (71) and a rear controller (72), and a front gas detector (41), a reduction catalyst chamber (51), an oxygenation chamber (52), an oxidation catalyst chamber (53) and a rear gas detector (42) are sequentially connected in series on the flue gas main pipe (32) along the flue gas emission direction. An ultra-low emission burner assembly is characterized in that a burner flow adjusting valve (62) of a controllable burner (6) is adjusted, so that the air-fuel ratio of the controllable burner (6) is slightly smaller than 1, and a trace amount of CO is generated and input into a reduction catalyst chamber (51). The combustion efficiency is improved, and waste gas emission is reduced.

Description

Technical Field

[0001] The utility model relates to the field of gasification of granular or powdered fuel in a suspended state, in particular to an ultra-low emission burner assembly. Background Art

[0002] With the development of modern industrial production and the improvement of living standards, air pollution has become a problem that people are very concerned about. x Under the action of sunlight, NO will cause photochemical reactions, forming photochemical smog, which will cause serious air pollution. Therefore, since the 1970s, NO x The problem of air pollution has been increasingly taken seriously.

[0003] At present, the mainstream NO x The control technologies include low nitrogen combustion technology (abbreviated as LNB) and flue gas denitrification technology, among which flue gas denitrification technology mainly includes selective non-catalytic reduction reaction (abbreviated as SNCR), selective catalytic reduction reaction (abbreviated as SCR) and SNCR / SCR combined denitrification technology. For large coal-fired boilers, SCR has been widely promoted and applied due to its mature technology and denitrification efficiency of more than 90%. With the development of my country's NO x Emission control is becoming increasingly stringent. Small and medium-sized coal-fired boilers, circulating fluidized bed boilers, cement kilns, ceramic kilns, waste incinerators and gas boilers are key industrial furnaces that emit NO. x As one of the emission sources of this type of furnace, the engineering application technology for denitrification continues to develop. Denitrification through high-efficiency low-nitrogen combustion technology combined with SNCR technology or SNCR / SCR combined technology is a new technical route.

[0004] Although the current coal-fired industrial furnace NO x The emission reduction effect is very significant, but excessive pursuit of denitrification efficiency can easily increase ammonia consumption, which in turn causes ammonia escape, resulting in secondary pollution and equipment corrosion.

[0005] There are two main types of flue gas denitrification technologies: dry method (selective catalytic reduction flue gas denitrification, selective non-catalytic reduction denitrification) and wet method. Compared with wet flue gas denitrification technology, the main advantages of dry flue gas denitrification technology are: low basic investment, simple equipment and process, removal of NO x The efficiency is also high, there is no wastewater and waste treatment, and it is not easy to cause secondary pollution.

[0006] Flue gas denitrification refers to the removal of generated NO x Reduce to N2, thereby removing NO from flue gas x According to the treatment process, it can be divided into wet denitrification and dry denitrification. Some researchers at home and abroad have also developed a method to use microorganisms to treat NO x Exhaust method.

[0007] 1. Principle of flue gas denitrification:

[0008] Selective catalytic reduction (SCR) denitrification uses NH3, CO, or hydrocarbons as reducing agents in the presence of a catalyst to reduce NO in the flue gas to N2 in the presence of oxygen. NH3, CO, H2, methane, ethylene, propane, propylene, and other reducing agents can be used in the SCR reaction. The highest NO removal efficiency is achieved when NH3 is used as the reducing gas. The SCR reaction is a redox reaction and therefore follows a redox mechanism or a Mars-van Krevelen-type mechanism. Currently, international scholars have reached a consensus that the reactant in the SCR reaction is NO, not NO2, and that O2 participates in the reaction.

[0009] The SNCR denitrification process is to spray a reducing agent containing amino groups such as liquid ammonia, ammonia water or urea dilute solution into the furnace temperature of 850℃~1100℃ without using a catalyst. The reducing agent will quickly decompose into NH3, which will then react with NO in the flue gas. x A selective redox reaction occurs to generate harmless gases such as N2 and H2O. Since no catalyst is used in the entire reaction process, it is called selective non-catalytic reduction denitrification technology.

[0010] The main reaction formula with NH3 as reducing agent is:

[0011] 4NH3+4NO+O2=4N2+6H2O,

[0012] 4NH3+2NO2+O2=3N2+6H2O,

[0013] The main chemical reactions using urea as a reducing agent are:

[0014] CO(NH2)2+H2O=2NH3+CO2,

[0015] 4NH3+4NO+O2=4N2+6H2O,

[0016] 4NH3+2NO2+O2=3N2+6H2O,

[0017] The main chemical reactions using CO as a reducing agent are:

[0018] 2CO+O2=2CO2,

[0019] 2CO+2NO=N2+2CO2,

[0020] Disadvantages of SNCR technology:

[0021] (1) Low denitrification efficiency, especially for NO in fuel-fired boilers x Emissions are only reduced by 30% to 50%;

[0022] (2) Strict temperature requirements, if the temperature is too low, NO x The conversion rate is low; when the temperature is too high, NH3 is easily oxidized to NO x , which offsets the ammonia removal efficiency;

[0023] (3) It is difficult to ensure sufficient mixing in gas phase reaction, the ammonia consumption is large, and the NH3 / NO x High molar ratio;

[0024] (4) The large amount of NH3 leakage not only pollutes the atmosphere, but also causes blockage of the air preheater due to the formation of (NH4)2SO4 when burning sulfur-containing fuels.

[0025] (5) When the chemical reaction occurs rapidly enough, the SNCR process is controlled by kinetic diffusion, so it is still difficult to achieve high efficiency.

[0026] (6) The influence of turbulence in the furnace and the degree of mixing of denitrification agents are still difficult to control.

[0027] 2. Types of SCR catalysts

[0028] The first type is precious metal catalysts such as Pt-Rh and Pd, which are usually supported by monolithic ceramics such as alumina. These catalysts were mostly used in the earliest SCR systems. They have high activity for SCR reactions and low reaction temperatures, but their disadvantage is that they have a certain oxidizing effect on NH3. Therefore, they were gradually replaced by metal oxide catalysts after the 1980s and 1990s. Currently, they are only used under low temperature conditions and for NO in exhaust gas after natural gas combustion. x removal.

[0029] The second category is metal oxide catalysts, mainly including V2O5 (WO3), Fe2O3, CuO, CrO x 、MnO x These catalysts are typically made of metal oxides such as MgO, MoO3, and NiO, or mixtures thereof, typically supported by TiO2, Al2O3, ZrO2, SiO2, or activated carbon (AC). These supports primarily provide a microporous structure with a large specific surface area, but exhibit minimal activity in the SCR reaction. When using this type of catalyst, ammonia or urea is typically used as the reducing agent. The reaction mechanism typically involves ammonia adsorption on the catalyst surface, while NO adsorption is minimal.

[0030] The third category is zeolite molecular sieves, primarily metal ion exchange zeolites produced through ion exchange. Hydrocarbons are typically used as reducing agents. Zeolites used primarily include Y-zeolite, ZSM series, MFI, MOR, and Cu-ZSM-5, particularly Cu-ZSM-5, which has been the subject of extensive research by international scholars. This type of catalyst is characterized by its high temperature range of activity, reaching up to 600°C. Furthermore, this type of catalyst is currently a focus of international research, but its industrial application remains limited.

[0031] During the denitrification process, ammonia in the flue gas is released through the reactor into the flue gas, a phenomenon known as ammonia slip. This can lead to several problems: it can easily cause ash accumulation and blockage in downstream equipment such as air preheaters, resulting in increased pressure drop and low-temperature corrosion; it can also affect fly ash quality, leading to dust accumulation on the electrodes of electrostatic precipitators or sticking of bag filters; it can also create a visible smoke column, increasing PM2.5 emissions; and its release into the atmosphere can negatively impact human health.

[0032] Effect of reaction temperature on SNCR reduction of NO x Based on common experiments and engineering operation conditions, the optimal temperature window for effective denitrification is 850°C to 1100°C. Generally, ammonia is between 850°C and 1050°C, and urea is between 900°C and 1100°C.

[0033] Too low or too high reaction temperature will lead to loss of reducing agent and decreased denitrification efficiency. If the temperature is too low, the NH3 reaction will be incomplete. Usually when it is below 800℃, the reaction rate will slow down, the denitrification efficiency will decrease, and ammonia slip will increase. When the temperature is too high, such as above 1200℃, the oxidation reaction of NH3 and O2 will intensify, and NH3 will be more easily oxidized to NO. x , NO x Emissions may rise instead of fall. Utility Model Content

[0034] In order to overcome the defects of the prior art and provide a combustion control device that improves combustion efficiency and reduces exhaust gas emissions, the utility model discloses an ultra-low emission burner assembly.

[0035] The utility model achieves the purpose of the invention through the following technical solutions:

[0036] An ultra-low emission burner assembly includes a heating furnace, a burner, a flue gas branch pipe, and a flue gas main pipe. The heating furnace is provided with at least two rows of at least two burners in each row. The exhaust port of each row of burners is respectively connected to a flue gas branch pipe, and both flue gas branch pipes are connected to the flue gas main pipe. The ultra-low emission burner assembly is characterized by:

[0037] It also includes a front gas detector, a rear gas detector, a reduction catalyst chamber, an oxygenation chamber, an oxidation catalyst chamber, a controllable burner, a front controller and a rear controller.

[0038] On the flue gas main pipe, a front gas detector, a reduction catalyst chamber, an oxygenation chamber, an oxidation catalyst chamber and a rear gas detector are connected in series in sequence along the direction of flue gas emission. The gas probe of the front gas detector is arranged in front of the reduction catalyst chamber of the flue gas main pipe, and the gas probe of the rear gas detector is arranged behind the oxidation catalyst chamber of the flue gas main pipe. Both the front gas detector and the rear gas detector detect the concentrations of CO and O2 in the flue gas main pipe.

[0039] No more than two controllable burners are installed on the flue gas branch pipe near the flue gas main, or a controllable burner is installed in front of the front gas detector on the flue gas main. The controllable burner includes a burner body and a burner flow control valve. The burner body is provided with a burner flow control valve on the gas inlet pipe and the air inlet pipe respectively. Each burner flow control valve and the front gas detector are connected to the front controller through a signal line;

[0040] The oxygenation chamber is connected to the outside atmosphere through an air pipe, and an air flow regulating valve is provided on the air pipe. The air flow regulating valve and the rear gas detector are connected to the rear controller through a signal line.

[0041] The ultra-low emission burner assembly is characterized by:

[0042] Both the burner flow control valve and the air flow control valve use solenoid valves, and both the front controller and the rear controller use single-chip microcomputers or programmable controllers.

[0043] The method for using the ultra-low emission burner assembly is characterized by being carried out in sequence according to the following steps:

[0044] i. When the controllable burner is installed on the flue gas branch pipe, adjust the burner flow control valve of the controllable burner near the flue outlet of the heating furnace so that the air-fuel ratio of the controllable burner is slightly less than 1, generating a small amount of CO that is input into the reduction catalyst chamber;

[0045] In the reduction catalytic chamber, CO and NO x Under the catalytic action of the reduction catalyst, N2 and CO2 are generated and input into the oxygenation chamber;

[0046] N2, CO2 and residual CO are added to the air in the oxygenation chamber and then input into the oxidation catalyst chamber;

[0047] In the oxidation catalytic chamber, CO and O2 react under the catalytic action of the oxidation catalyst to generate CO2 which is then discharged through the flue gas main pipe;

[0048] ii. When the controllable burner is installed on the flue gas main, adjust the burner flow control valve of the controllable burner so that the air-fuel ratio of the controllable burner is slightly less than 1, generating a small amount of CO and CH4 that are input into the reduction catalyst chamber;

[0049] In the reduction catalytic chamber, CO, CH4 and NO x Under the catalytic action of the reduction catalyst, N2, H2O and CO2 are generated and input into the oxygenation chamber;

[0050] N2, H2O, CO2 and residual CO and CH4 are added to the air in the oxygenation chamber and then input into the oxidation catalytic chamber;

[0051] In the oxidation catalytic chamber, CO and CH4 react with O2 respectively under the catalytic action of the oxidation catalyst to generate CO2 and H2O, which are discharged through the flue gas main pipe.

[0052] The method for using the ultra-low emission burner assembly is characterized in that: in steps i and ii, the air-fuel ratio of the controllable burner is not less than 0.99 and not greater than 1.

[0053] Theoretically, when gases with different calorific values ​​are completely burned, their air-fuel ratios are different, but they are also a relatively fixed value, expressed as k, which is called the theoretical air-fuel ratio of complete combustion. For example, 1Nm 3 Natural gas requires 8.5 Nm to burn completely 3 The k value of air is 8.5.

[0054] Similarly, the k values ​​of gases with other calorific values ​​are different due to their different calorific values. For example, coke oven gas COG, k=4.2; converter gas, k=1.7; blast furnace gas, k=0.8.

[0055] During production, a certain amount of air is added for safety reasons. Excess air coefficient = actual air usage / theoretical air volume required for complete combustion. When the gas is completely burned, the excess air coefficient is 1. If the excess air coefficient is slightly less than 1, incomplete combustion occurs, producing CO. The national standard requires CO emissions from heating furnace flue gas to be less than 1000ppm. Therefore, the excess air coefficient of the controllable burner is set slightly less than 1 to produce trace amounts of CO. Theoretically, if 1% of the gas is not burned, the flue gas will contain 10,000ppm of CO. Therefore, the excess air coefficient is controlled between 0.99 and 1.

[0056] The utility model utilizes the CO generated by incomplete combustion of the burner itself as a reducing agent. The technical points are:

[0057] 1. The amount of reducing agent CO produced must be controlled within a reasonable range and combined with the combustion characteristics of the burner. Too low a CO concentration will affect the reaction effect, while too high a concentration will cause the emission of residual CO and is not energy-efficient.

[0058] 2. The burnout rate of the controllable burner should be high, and the oxygen content during complete combustion (i.e., no CO in the flue gas) should be as low as possible, because the oxidizing property of O2 is greater than the reducing property of CO. In the presence of O2, the reduction reaction rate of NO and CO is lower than the oxidation reaction rate of CO and O2, which affects the conversion efficiency and even causes failure, and also reduces the service life of the catalyst.

[0059] 3. The combustion control sensitivity of the intelligent burner should be high, because the CO demand is at the ppm level, and the control of general burners is at the percentage level.

[0060] 4. The amount of reducing catalyst and oxidizing catalyst, the life and cost of the catalyst are also important parameters that directly affect the promotion and implementation of the project.

[0061] The utility model has the following beneficial effects:

[0062] 1. Use CO as the denitrification reducing agent instead of NH3;

[0063] 2. The source of the reducing agent CO is different from that of NH3. NH3 is injected separately, while CO is generated by the burner itself.

[0064] 3. Will not cause secondary NH3 pollution;

[0065] 4. CO is only an intermediate product, and there is no CO in the final emissions, which will not increase CO emission pollution;

[0066] 5. The burner and denitrification reduction oxidation system are integrated and neither can be missing;

[0067] 6. Wide range of application scenarios: The design method of combining burner combustion and reduction denitrification is related to the type of furnace used, the environment, and the specific structure of the burner, but is not limited to a certain burner:

[0068] (1) On open flame furnaces such as hot rolling heating furnaces, trolley furnaces, and annealing furnaces, a set of

[0069] (2) For radiant tube burner heating furnaces and annealing furnaces, one set can be installed on the flue in conjunction with the existing burner, or one set can be installed independently.

[0070] (3) On existing furnaces equipped with NH3 catalytic denitrification, the system can also be retrofitted in conjunction with the existing installation space;

[0071] 7. High denitrification efficiency, surpassing low NO x (ie less than 100mg / Nm 3 ) requirements to achieve ultra-low NO x (ie less than 50mg / Nm 3 ) standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is a schematic diagram of the structure of the utility model when the controllable burner is arranged on the flue gas branch pipe.

[0073] Figure 2 This is a schematic diagram of the connection between the front gas detector, rear gas detector, reduction catalyst chamber, oxygenation chamber, oxidation catalyst chamber and flue gas main pipe in the utility model.

[0074] Figure 3 The utility model is a structural schematic diagram when the controllable burner is arranged on the flue gas main pipe. DETAILED DESCRIPTION

[0075] The present invention is further described below through specific embodiments. Example

[0076] An ultra-low emission burner assembly includes a heating furnace 1, a burner 2, a flue gas branch pipe 31, a flue gas main pipe 32, a front gas detector 41, a rear gas detector 42, a reduction catalyst chamber 51, an oxygenation chamber 52, an oxidation catalyst chamber 53, a controllable burner 6, a front controller 71 and a rear controller 72, such as Figure 1 As shown, the specific structure is:

[0077] The heating furnace 1 is provided with at least two rows of at least two burners 2 in each row, and the exhaust port of each row of burners 2 is connected to a flue gas branch pipe 31, and the two flue gas branch pipes 31 are connected to the flue gas main pipe 32;

[0078] like Figure 2 As shown: on the flue gas main pipe 32, a front gas detector 41, a reduction catalyst chamber 51, an oxygenation chamber 52, an oxidation catalyst chamber 53 and a rear gas detector 42 are connected in series in sequence along the flue gas emission direction. The gas probe of the front gas detector 41 is arranged in front of the reduction catalyst chamber 51 of the flue gas main pipe 32, and the gas probe of the rear gas detector 42 is arranged behind the oxidation catalyst chamber 53 of the flue gas main pipe 32. Both the front gas detector 41 and the rear gas detector 42 detect the concentrations of CO and O2 in the flue gas main pipe 32;

[0079] No more than two controllable burners 6 are provided on the flue gas branch pipe 31 near the flue gas main pipe 32. The controllable burners include a burner body 61 and a burner flow control valve 62. The burner body 61 is provided with a burner flow control valve 62 on the gas inlet pipe and the air inlet pipe, respectively. Each burner flow control valve 62 and the front gas detector 41 are connected to the front controller 71 via a signal line.

[0080] The oxygenation chamber 52 is connected to the outside atmosphere through an air pipe 33 , on which an air flow regulating valve 63 is provided. The air flow regulating valve 63 and the rear gas detector 42 are both connected to the rear controller 72 via a signal line.

[0081] In this embodiment:

[0082] Both the burner flow regulating valve 62 and the air flow regulating valve 63 are electromagnetic valves, and both the front controller 71 and the rear controller 72 are single chip microcomputers or programmable controllers.

[0083] When using this embodiment, the following steps are implemented in sequence:

[0084] Adjust the burner flow control valve 62 of the controllable burner 6 so that the air-fuel ratio of the controllable burner 6 is not less than 0.99 and not greater than 1, thereby generating a small amount of CO which is input into the reduction catalyst chamber 51;

[0085] In the reduction catalyst chamber 51, CO and NO x Under the catalytic action of the reduction catalyst, N2 and CO2 are generated and input into the oxygenation chamber 52;

[0086] N2, CO2 and residual CO are supplied to the oxidation catalytic chamber 53 after being supplemented with air in the oxygenation chamber 52;

[0087] In the oxidation catalyst chamber 53 , CO and O 2 react under the catalytic action of the oxidation catalyst to generate CO 2 which is then discharged through the flue gas main pipe 32 .

[0088] This embodiment is suitable for a heating system under a production process with daily stable production, relatively stable furnace temperature and small fluctuation, and a denitrification system is installed on the flue. Example

[0089] An ultra-low emission burner assembly includes a heating furnace 1, a burner 2, a flue gas branch pipe 31, a flue gas main pipe 32, a front gas detector 41, a rear gas detector 42, a reduction catalyst chamber 51, an oxygenation chamber 52, an oxidation catalyst chamber 53, a controllable burner 6, a front controller 71 and a rear controller 72, such as Figure 3 As shown, the specific structure is:

[0090] The heating furnace 1 is provided with at least two rows of at least two burners 2 in each row, and the exhaust port of each row of burners 2 is connected to a flue gas branch pipe 31, and the two flue gas branch pipes 31 are connected to the flue gas main pipe 32;

[0091] like Figure 2 As shown: on the flue gas main pipe 32, a front gas detector 41, a reduction catalyst chamber 51, an oxygenation chamber 52, an oxidation catalyst chamber 53 and a rear gas detector 42 are connected in series in sequence along the flue gas emission direction. The gas probe of the front gas detector 41 is arranged in front of the reduction catalyst chamber 51 of the flue gas main pipe 32, and the gas probe of the rear gas detector 42 is arranged behind the oxidation catalyst chamber 53 of the flue gas main pipe 32. Both the front gas detector 41 and the rear gas detector 42 detect the concentrations of CO and O2 in the flue gas main pipe 32;

[0092] A controllable burner 6 is provided in front of the front gas detector 41 on the flue gas main 32. The controllable burner includes a burner body 61 and a burner flow control valve 62. The burner body 61 is provided with a burner flow control valve 62 on the gas inlet pipe and the air inlet pipe, respectively. Each burner flow control valve 62 and the front gas detector 41 are connected to the front controller 71 via a signal line.

[0093] The oxygenation chamber 52 is connected to the outside atmosphere through an air pipe 33 , on which an air flow regulating valve 63 is provided. The air flow regulating valve 63 and the rear gas detector 42 are both connected to the rear controller 72 via a signal line.

[0094] In this embodiment:

[0095] Both the burner flow regulating valve 62 and the air flow regulating valve 63 are electromagnetic valves, and both the front controller 71 and the rear controller 72 are single chip microcomputers or programmable controllers.

[0096] When using this embodiment, the following steps are implemented in sequence:

[0097] Adjust the burner flow control valve 62 of the controllable burner 6 so that the air-fuel ratio of the controllable burner 6 is not less than 0.99 and not greater than 1, thereby generating a small amount of CO and CH4 which are input into the reduction catalyst chamber 51;

[0098] In the reduction catalyst chamber 51, CO, CH4 and NO x Under the catalytic action of the reduction catalyst, N2, H2O and CO2 are generated and input into the oxygenation chamber 52;

[0099] N2, H2O, CO2 and residual CO, CH4 are supplied to the oxidation catalytic chamber 53 after being supplemented with air in the oxygenation chamber 52;

[0100] In the oxidation catalytic chamber 53 , CO and CH 4 react with O 2 respectively under the catalytic action of the oxidation catalyst to generate CO 2 and H 2 O, which are then discharged through the flue gas main pipe 32 .

[0101] This embodiment is suitable for intermittent production furnaces, because the furnace temperature changes greatly, CO and NO x The changes are large. If only a certain burner of the furnace is relied upon for adjustment, it will be difficult, especially since the main burner has a large power. The valves and pipelines required to change the air-fuel ratio are large and take up space. Therefore, a controllable burner 6 is added to the flue gas main pipe 32. The controllable burner 6 can output CO and CH4. If the coke oven gas mainly produces CO, it is easier. The main component of natural gas is CH4. The generated CO and CH4 can both be used as reducing agents.

[0102] The difference between Example 1 and Example 2 lies in how to generate stable reducing agents such as CO. The core equipment includes three functional areas: a reduction catalyst chamber 51, an oxygenation chamber 52, and an oxidation catalyst chamber 53. The main function of the reduction catalyst chamber 51 is to selectively catalyze the reduction of CO and NO. x A catalytic reduction reaction occurs to produce N2 and CO2. Research focuses on the selection of precious metal catalysts and the determination of process parameters for the catalytic reduction reaction, such as flue gas flow rate, flue gas temperature, residence time, and reaction concentration. A certain amount of air is introduced into the oxygenation chamber 52 based on the residual CO concentration. The structural design ensures uniform injection and adequate mixing, while minimizing the length of the oxygenation chamber 52. The oxidation catalytic chamber 53 primarily promotes the CO oxidation reaction, requiring the appropriate selection of catalysts and the determination of process parameters such as temperature.

Claims

1. An ultra-low emission burner assembly, comprising a heating furnace (1), a burner (2), a flue gas branch pipe (31) and a flue gas main pipe (32), wherein the heating furnace (1) is provided with at least two rows of at least two burners (2) in each row, the exhaust ports of each row of burners (2) are respectively connected to a flue gas branch pipe (31), and both flue gas branch pipes (31) are connected to the flue gas main pipe (32), wherein: It also includes a front gas detector (41), a rear gas detector (42), a reduction catalyst chamber (51), an oxygenation chamber (52), an oxidation catalyst chamber (53), a controllable burner (6), a front controller (71) and a rear controller (72), On the flue gas main pipe (32), a front gas detector (41), a reduction catalyst chamber (51), an oxygenation chamber (52), an oxidation catalyst chamber (53), and a rear gas detector (42) are sequentially connected in series along the flue gas emission direction. The gas probe of the front gas detector (41) is arranged in front of the reduction catalyst chamber (51) of the flue gas main pipe (32), and the gas probe of the rear gas detector (42) is arranged behind the oxidation catalyst chamber (53) of the flue gas main pipe (32). Both the front gas detector (41) and the rear gas detector (42) detect the concentrations of CO and O2 in the flue gas main pipe (32); No more than two controllable burners (6) are provided on the flue gas branch pipe (31) near the flue gas main pipe (32), or one controllable burner (6) is provided on the flue gas main pipe (32) in front of the front gas detector (41), the controllable burner comprising a burner body (61) and a burner flow regulating valve (62), a burner flow regulating valve (62) is provided on the gas inlet pipe and the air inlet pipe of the burner body (61), and each burner flow regulating valve (62) and the front gas detector (41) are connected to the front controller (71) via a signal line; The oxygenation chamber (52) is connected to the outside atmosphere via an air delivery pipe (33). An air flow regulating valve (63) is provided on the air delivery pipe (33). The air flow regulating valve (63) and the rear gas detector (42) are both connected to the rear controller (72) via a signal line.

2. The ultra-low emission burner assembly according to claim 1, wherein: Both the burner flow regulating valve (62) and the air flow regulating valve (63) are electromagnetic valves, and both the front controller (71) and the rear controller (72) are single chip microcomputers or programmable controllers.

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