Ultra-low emission burner assembly and use method thereof

Abstract

The invention relates to the field of gasification of granular or powdery fuel in a suspension state, in particular to an ultralow-emission burner assembly and a using method thereof. 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. The ultralow-emission burner assembly and the using method thereof are 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 invention relates to the field of gasification of granular or powdered fuel in a suspended state, and in particular to an ultra-low emission burner assembly and a use method thereof. Background Art

[0002] With the development of modern industrial production and the improvement of living standards, air pollution has become a problem of great concern to people. 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 x The emission control is becoming increasingly strict. 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 It is one of the emission sources of this type of furnace. The engineering application technology for denitrification of this type of furnace 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, and 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 the 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 xExhaust method.

[0007] 1. Principle of flue gas denitrification: 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, etc. can be used as reducing agents for the SCR reaction. The highest NO removal efficiency can be achieved when NH3 is used as the reducing gas. The SCR reaction is a redox reaction, so it follows a redox mechanism or a Mars-van Krevelen-type mechanism. At present, foreign scholars have reached a consensus that the reactant of the SCR reaction is NO, not NO2, and O2 participates in the reaction.

[0008] The SNCR denitrification process is to spray a reducing agent containing amino groups such as liquid ammonia, ammonia water or dilute urea 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 is carried out 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.

[0009] The main reaction equation with NH3 as reducing agent is: 4NH3+4NO+O2=4N2+6H2O, 4NH3+2NO2+O2=3N2+6H2O, The main chemical reactions using urea as a reducing agent are: CO(NH2)2+H2O=2NH3+CO2, 4NH3+4NO+O2=4N2+6H2O, 4NH3+2NO2+O2=3N2+6H2O, The main chemical reactions using CO as a reducing agent are: 2CO+O2=2CO2, 2CO+2NO=N2+2CO2, Disadvantages of SNCR technology: (1) Low denitrification efficiency, especially for oil-fired boilers, where NOx emissions are only reduced by 30% to 50%; (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 removal efficiency of ammonia; (3) It is difficult to ensure sufficient mixing in gas phase reactions, resulting in high consumption of liquid ammonia and high NH3 / NO x High molar ratio; (4) Large amounts of NH3 leakage not only pollute the atmosphere, but also clog the air preheater due to the formation of (NH4)2SO4 when burning sulfur-containing fuels.

[0010] (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.

[0011] (6) The influence of turbulence in the furnace and the degree of mixing of the denitrification agent are still difficult to control.

[0012] 2. Types of SCR catalysts The first type is precious metal catalysts such as Pt-Rh and Pd, which usually use monolithic ceramics such as alumina as carriers. This type of catalyst is mostly used in the earliest SCR systems. It has high activity for SCR reaction and low reaction temperature, but the disadvantage is that it has a certain oxidation effect on NH3. Therefore, it has been gradually replaced by metal oxide catalysts since the 1980s and 1990s. At present, it is only used for the removal of NOx in tail gas under low temperature conditions and after natural gas combustion.

[0013] The second category is metal oxide catalysts, mainly including V2O5 (WO3), Fe2O3, CuO, CrO x 、MnO x , MgO, MoO3, NiO and other metal oxides or their combined mixtures, usually with TiO2, Al2O3, ZrO2, SiO2, activated carbon (AC) and the like as carriers, and these carriers usually mainly provide microporous structures with large specific surface areas and have very little activity in SCR reactions. When this type of catalyst is used, ammonia or urea is usually used as a reducing agent. The reaction mechanism is usually that ammonia is adsorbed on the surface of the catalyst, while the adsorption of NO is very small.

[0014] The third type is zeolite molecular sieve type, which is mainly metal ion exchange zeolite made by ion exchange method. Hydrocarbons are usually used as reducing agents. The types of zeolites used mainly include Y-zeolite, ZSM series, MFI, MOR, etc., especially Cu-ZSM-5, which has been studied by foreign scholars. This type of catalyst is characterized by a high temperature range of activity, which can reach up to 600°C. At the same time, this type of catalyst is also the focus of research by foreign scholars, but there are not many industrial applications.

[0015] During the denitrification process, ammonia that does not participate in the reaction exists in the flue gas and is discharged into the flue gas through the reactor is called ammonia escape. Ammonia escape may cause the following problems: it is easy to cause ash accumulation and blockage of downstream devices such as air preheaters, resulting in increased pressure loss and low-temperature corrosion; it affects the quality of fly ash, causing ash accumulation on the poles of electrostatic precipitators or sticking of bag filters; it forms visible smoke columns and increases PM2.5 emissions; and it has a negative impact on human health when released into the atmosphere.

[0016] The reaction temperature is crucial to the efficiency of SNCR in reducing NOx. From the perspective of common experiments and engineering operation, the optimal temperature window for effective denitrification reaction is 850℃~1100℃. Generally, ammonia is between 850℃~1050℃, and urea is between 900℃~1100℃.

[0017] Too low or too high reaction temperature will lead to loss of reducing agent and decreased denitration 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 denitration efficiency will decrease, and ammonia escape will increase. When the temperature is too high, for example, when the temperature is 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. Summary of the invention

[0018] In order to overcome the defects of the prior art and provide a combustion control device for improving combustion efficiency and reducing exhaust gas emissions, the present invention discloses an ultra-low emission burner assembly and a method for using the same.

[0019] The present invention achieves the purpose of the invention through the following technical solutions: An ultra-low emission burner assembly comprises 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 ports of each row of burners are respectively connected to a flue gas branch pipe, and the two flue gas branch pipes are connected to the flue gas main pipe. The characteristics are: 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. 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 flue gas emission direction. 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 concentration of CO and O2 in the flue gas main pipe. No more than two controllable burners are installed on the flue gas branch pipe near the flue gas main pipe, or a controllable burner is installed in front of the front gas detector on the flue gas main pipe. The controllable burner includes a burner body and a burner flow regulating valve. The burner body is provided with a burner flow regulating valve on the gas inlet pipe and the air inlet pipe respectively. Each burner flow regulating valve and the front gas detector are connected to the front controller through a signal line; The oxygenation chamber is connected to the outside atmosphere through an air pipe, on which an air flow regulating valve is arranged. The air flow regulating valve and the rear gas detector are connected to the rear controller through a signal line.

[0020] The ultra-low emission burner assembly is characterized by: 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.

[0021] The method for using the ultra-low emission burner assembly is characterized by being implemented in sequence according to the following steps: 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 to make the air-fuel ratio of the controllable burner slightly less than 1, so as to generate a small amount of CO and input it into the reduction catalyst chamber; 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; N2, CO2 and residual CO are fed into the oxidation catalytic chamber after supplementing air in the oxygenation chamber; In the oxidation catalytic chamber, CO and O2 react under the catalytic action of the oxidation catalyst to generate CO2 which is discharged through the flue gas main pipe; 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, and a small amount of CO and CH4 are generated and input into the reduction catalyst chamber; 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; N2, H2O, CO2 and residual CO and CH4 are fed into the oxidation catalytic chamber after supplementing air in the oxygenation chamber; 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.

[0022] 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.

[0023] Theoretically, when gases with different calorific values ​​are completely burned, their air-fuel ratios are different, but they are also a relatively fixed value, represented by k, called the theoretical air-fuel ratio for complete combustion. 3 8.5Nm is required for complete combustion of natural gas 3 For air, the k value is 8.5.

[0024] Similarly, other fuel gases have different k values ​​due to their different calorific values, such as coke oven gas COG, k=4.2; converter gas, k=1.7; blast furnace gas, k=0.8.

[0025] During production, a certain amount of air is added for safety. Excess air coefficient = actual air usage / theoretical air volume required for complete combustion. When the gas is completely burned, its excess air coefficient is 1. If the excess air coefficient is slightly less than 1, incomplete combustion occurs and CO is produced. The national standard requires that the CO emission in the flue gas of the heating furnace is less than 1000ppm. Therefore, the excess air coefficient of the controllable burner is slightly less than 1 to produce a trace amount of CO. According to theoretical calculations, 1% of the gas that is not burned can cause a CO content of 10,000ppm in the flue gas, so the excess air coefficient is controlled between 0.99-1.

[0026] The present invention utilizes CO generated by incomplete combustion of the burner itself as a reducing agent, and the technical key points are: 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 CO concentration will affect the reaction effect, while too high concentration will cause the emission of residual CO and is not energy-saving.

[0027] 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.

[0028] 3. The combustion control sensitivity of the intelligent burner should be high, because the demand for CO is at the ppm level, and the control of general burners is at the percentage level.

[0029] 4. The amount of reducing catalyst and oxidizing catalyst, the life and cost of the catalyst are also important parameters, which directly affect the promotion and implementation of the project.

[0030] The present invention has the following beneficial effects: 1. Use CO as denitrification reducing agent instead of NH3; 2. The source of reducing agent CO is different from that of NH3. NH3 is injected additionally, while CO is produced by the burner itself. 3. Will not cause secondary pollution of NH3; 4. CO is only an intermediate product, and there is no CO in the final emission, which will not increase CO emission pollution; 5. The burner and denitrification reduction oxidation system are integrated and are indispensable; 6. Wide application scenarios: The design method combining burner combustion and reduction denitrification is related to the type of furnace, environment, and specific structure of the burner, but is not limited to a certain burner: (1) On open flame furnaces such as hot rolling heating furnaces, trolley furnaces, annealing furnaces, etc., one set can be installed on the flue. (2) For radiant tube burner heating furnaces and annealing furnaces, one set can be installed on the flue in conjunction with the existing burners, or one set can be installed independently. (3) On an existing furnace equipped with NH3 catalytic denitrification, it can also be modified in combination with the existing installation space; 7. High denitrification efficiency, can surpass 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

[0031] Figure 1 This is a schematic diagram of the structure of the present invention when the controllable burner is arranged on the flue gas branch pipe. Figure 2 It is a connection diagram of the front gas detector, the rear gas detector, the reduction catalyst chamber, the oxygenation chamber, the oxidation catalyst chamber and the flue gas main pipe in the present invention. Figure 3 It is a structural schematic diagram of the present invention when the controllable burner is arranged on the flue gas main pipe. DETAILED DESCRIPTION

[0032] The present invention is further described below by means of specific examples. Example

[0033] 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: The heating furnace 1 is provided with at least two rows of at least two burners 2 in each row, and the exhaust ports of the burners 2 in each row are respectively 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; like Figure 2As 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 concentration of CO and O2 in the flue gas main pipe 32; No more than two controllable burners 6 are arranged 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 regulating valve 62. The burner flow regulating valves 62 are respectively arranged on the gas inlet pipe and the air inlet pipe of the burner body 61. Each burner flow regulating valve 62 and the front gas detector 41 are connected to the front controller 71 through a signal line. The oxygenation chamber 52 is connected to the outside atmosphere through an air pipe 33, and an air flow regulating valve 63 is provided on the air pipe 33. The air flow regulating valve 63 and the rear gas detector 42 are connected to the rear controller 72 through a signal line.

[0034] In this embodiment: 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.

[0035] When this embodiment is used, the following steps are implemented in sequence: The burner flow regulating valve 62 of the controllable burner 6 is adjusted to make the air-fuel ratio of the controllable burner 6 not less than 0.99 and not greater than 1, so as to generate a small amount of CO which is input into the reduction catalyst chamber 51; 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; N2, CO2 and residual CO are supplied to the oxidation catalytic chamber 53 after being supplemented with air in the oxygenation chamber 52; 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 .

[0036] This embodiment is suitable for the heating system under the production process with daily stable production, relatively stable furnace temperature and small fluctuation, and the denitrification system is installed on the flue. Example

[0037] 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 3As shown, the specific structure is: The heating furnace 1 is provided with at least two rows of at least two burners 2 in each row, and the exhaust ports of the burners 2 in each row are respectively 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; 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 concentration of CO and O2 in the flue gas main pipe 32; A controllable burner 6 is provided in front of the front gas detector 41 on the flue gas main pipe 32. The controllable burner includes a burner body 61 and a burner flow regulating valve 62. The burner flow regulating valves 62 are provided on the gas inlet pipe and the air inlet pipe of the burner body 61, respectively. Each burner flow regulating valve 62 and the front gas detector 41 are connected to the front controller 71 through a signal line. The oxygenation chamber 52 is connected to the outside atmosphere through an air pipe 33, and an air flow regulating valve 63 is provided on the air pipe 33. The air flow regulating valve 63 and the rear gas detector 42 are connected to the rear controller 72 through a signal line.

[0038] In this embodiment: 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.

[0039] When this embodiment is used, the following steps are implemented in sequence: The burner flow regulating valve 62 of the controllable burner 6 is adjusted so that the air-fuel ratio of the controllable burner 6 is not less than 0.99 and not greater than 1, and a trace amount of CO and CH4 are generated and input into the reduction catalyst chamber 51; 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; 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; In the oxidation catalyst 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 .

[0040] This embodiment is suitable for intermittent production furnaces, because their furnace temperature varies greatly, CO and NO xThe changes are large. If only a certain burner of the furnace is used for adjustment, it is difficult, especially 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, and the generated CO and CH4 can be used as reducing agents.

[0041] The difference between Example 1 and Example 2 is 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 noble metal reduction catalyst to convert CO and NO into oxygen. x The catalytic reduction reaction generates N2 and CO2. The research focuses on the selection of precious metal catalysts and the determination of process parameters of the catalytic reduction reaction, such as flue gas flow rate, flue gas temperature, residence time, reaction concentration, etc. A certain amount of air is filled into the oxygenation chamber 52 mainly according to the residual CO concentration. The structural design should ensure uniform injection and sufficient mixing, and minimize the length of the oxygenation chamber 52. The oxidation catalytic chamber 53 mainly promotes the oxidation reaction of CO, and the reasonable 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 direction of flue gas emission; 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); 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 arranged on the flue gas branch pipe (31) near the flue gas main pipe (32), or a controllable burner (6) is arranged on the flue gas main pipe (32) in front of the front gas detector (41), the controllable burner comprises a burner body (61) and a burner flow regulating valve (62), the burner body (61) is provided with a burner flow regulating valve (62) on the gas inlet pipe and the air inlet pipe, respectively, 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 arranged on the air delivery pipe (33), and the air flow regulating valve (63) and the rear gas detector (42) are connected to the rear controller (72) via a signal line.

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

3. The method for using the ultra-low emission burner assembly according to claim 1 or 2, characterized in that: Follow the steps below to implement: i. When the controllable burner (6) is disposed on the flue gas branch pipe (31), the burner flow control valve (62) of the controllable burner (6) is adjusted so that the air-fuel ratio of the controllable burner (6) is slightly less than 1, and a small amount of CO is generated and input into the reduction catalyst chamber (51); In the reduction catalyst chamber (51), CO and NO x Under the catalytic action of the reduction catalyst, N2 and CO2 are generated by reaction and input into the oxygenation chamber (52); N2, CO2 and residual CO are supplied with air in the oxygenation chamber (52) and then input into the oxidation catalytic chamber (53); In the oxidation catalytic chamber (53), 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 (32); ii. When the controllable burner (6) is disposed on the flue gas main (32), the burner flow control valve (62) of the controllable burner (6) is adjusted so that the air-fuel ratio of the controllable burner (6) is slightly less than 1, and a trace amount of CO and CH4 are generated and input into the reduction catalyst chamber (51); 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); N2, H2O, CO2 and residual CO and CH4 are supplied to the oxidation catalytic chamber (53) after being supplemented with air in the oxygenation chamber (52); In the oxidation catalytic chamber (53), CO and CH4 react with O2 respectively under the catalytic action of the oxidation catalyst to generate CO2 and H2O, which are then discharged through the flue gas main pipe (32).

4. The method for using the ultra-low emission burner assembly according to claim 3, characterized in that: During steps i and ii, the air-fuel ratio of the controllable burner (6) is not less than 0.99 and not greater than 1.

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