A compact premixed ultra-low nitrogen combustion device

Abstract

The present invention relates to the technical field of combustion devices, and in particular to a compact premixed ultra-low nitrogen combustion device, comprising: an outer duct, a burner shell, an adjusting device, a primary air duct, a central gas pipe and a number of surrounding combustion components, the burner shell is connected to the outer duct, the adjusting device is arranged inside the burner shell, and the burner shell is provided with a combustion-supporting air port; the outlet of the outer duct is connected with a flue gas guide component, the primary air duct runs through the outer duct and the primary air duct is sleeved on the central gas pipe, a swirl disk is provided at the end of the primary air duct, a combustion head adjacent to the swirl disk is provided at the front end of the central gas pipe, and the combustion head is provided with a gas spray hole. The present invention combines the two combustion technologies of air-flue gas premixing and air-fuel premixing on the basis of air and fuel grading technology to further reduce the emission of nitrogen oxides.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion devices, and in particular to a compact premixed ultra-low nitrogen combustion device, which simultaneously applies two combustion technologies, air-smoke premixing and air-gas premixing, to one burner based on air staging technology and gas staging technology, thereby reducing the emission of nitrogen oxides and achieving the purpose of low nitrogen emissions. Background Art

[0002] Generally, nitrogen oxides (NOx) can be divided into the following types: fuel NOx, which is formed by oxidation of nitrogen components in a chemically combined form with fuel during combustion; thermal NOx, which is produced when nitrogen in the combustion air is freed at high temperatures; and prompt NOx, which is rapidly produced when hydrocarbon series mineral fuels are exposed to high temperature environments in high concentrations.

[0003] Nitrogen oxides (NOx) have a negative impact on the atmospheric environment and human life, leading to the frequent occurrence of severe smog pollution weather. Therefore, researchers have long been developing low-NOx burner technology.

[0004] This technology has gone through the following three generations of development:

[0005] The first generation: represented by air classification technology, which supplies air to the combustion furnace by classification to prevent the rapid oxidation reaction caused by the fuel in the combustion furnace, reduce the flame temperature, and thus reduce thermal nitrogen oxides.

[0006] The second generation: represented by gas staging technology, in which two jets of gas are injected into the center (about 5% to 25%) and the periphery (75% to 95%), so that the center has excess air and the outside air is insufficient, suppressing the oxidation reaction of the periphery that occupies most of the flame, preventing the flame temperature from rising, thereby reducing thermal nitrogen oxides. Although rapid nitrogen oxides may be generated due to the lack of air in the surrounding flame, by injecting gas to the periphery to ensure that the flame temperature is below 1000°C, it is possible to simultaneously achieve the functions of maintaining the flame and suppressing the generation of rapid NOx.

[0007] The third generation: represented by IFGR (internal flue gas recirculation), which can realize the self-circulation (Recirculation) of combustion gas in the combustion chamber after the first combustion, so that the combustion gas and flame are mixed, the flame temperature is reduced, and thus thermal nitrogen oxides can be reduced.

[0008] The above three technologies are difficult to meet the national ultra-low nitrogen emission requirements of 30mg / Nm3, specifically:

[0009] 1. The first generation uses air staged combustion technology, and the nitrogen oxide emissions of gas burners are generally around 160mg / Nm3;

[0010] 2. The second generation uses fuel staged combustion technology based on air staged combustion technology. The nitrogen oxide emissions of gas burners are generally around 120mg / Nm3;

[0011] 3. The third generation uses air staged combustion technology, fuel staged, and IFGR (internal flue gas circulation) technology. The nitrogen oxide emissions of gas burners are generally around 80mg / Nm3;

[0012] Today, in the 21st century, according to the requirements of the National Environmental Protection Law, the above technologies cannot meet the increasingly stringent emission requirements, so it is necessary to develop a more low-nitrogen and environmentally friendly gas combustion technology. Summary of the invention

[0013] To solve the above problems, the main purpose of the present invention is to provide a compact premixed ultra-low nitrogen combustion device, which combines the two combustion technologies of air-flue gas premixing and air-fuel premixing on the basis of air and fuel staging technology to further reduce the emission of nitrogen oxides.

[0014] To achieve the above object, the technical solution adopted by the present invention is:

[0015] A compact premixed ultra-low nitrogen combustion device is arranged on the outer wall of a combustion chamber, characterized in that the compact premixed ultra-low nitrogen combustion device comprises: an outer conduit, a burner shell, an adjustment device, a primary air duct, a central gas pipe and a plurality of surrounding combustion components, the burner shell is connected to the outer conduit, the adjustment device is arranged inside the burner shell, and the burner shell is provided with a combustion-supporting air port; wherein,

[0016] An outer conduit, one end of which is inserted into the combustion chamber, and an outlet of the outer conduit is connected to a smoke guide assembly for introducing air and smoke into the combustion chamber;

[0017] The primary air duct passes through the outer duct and is sleeved on the central gas pipe. A swirl disk is provided at the end of the primary air duct. A burner head adjacent to the swirl disk is provided at the front end of the central gas pipe. The burner head is provided with a gas spray hole. The gas is sprayed from the gas spray hole into a blowing pipe and premixed with air before being injected into the furnace for combustion.

[0018] A plurality of peripheral combustion components penetrate the outer duct and are evenly arranged on the periphery of the primary air duct. The peripheral combustion components are used for premixing the fuel gas and the air, and injecting the premixed mixed gas into the furnace at a high speed for combustion.

[0019] Furthermore, the surrounding combustion assembly includes an air intake chamber, a mixing tube and a plurality of surrounding gas pipes, one end of the mixing tube is inserted into the combustion chamber, the other end of the mixing tube is connected to the air intake chamber, and the air intake chamber is provided with a guide port;

[0020] A plurality of the surrounding gas pipes are evenly distributed in the outer circle of the primary air duct, and the front ends of the surrounding gas pipes are provided with gas nozzles with reduced diameters, and the gas nozzles are inserted into the air intake chamber.

[0021] Furthermore, the smoke guide assembly includes a reduced diameter connecting pipe and a burner outer ring conduit connected to the reduced diameter connecting pipe, and a smoke guide port is provided between the reduced diameter connecting pipe and the burner outer ring conduit.

[0022] Furthermore, the compact premixed ultra-low nitrogen combustion device also includes a mounting plate, and the outer conduit is fixed to the outer wall of the combustion chamber through the mounting plate.

[0023] Furthermore, the compact premixed ultra-low nitrogen combustion device also includes an ambient gas main pipe, which is connected to the plurality of ambient gas pipes.

[0024] Furthermore, the flow rate of the central gas pipe accounts for 10%-15% of the total gas volume of the entire device, and the flow rate of the surrounding gas main pipes accounts for 85%-90% of the total gas volume of the entire device.

[0025] Furthermore, the burner head is a trumpet-shaped burner head, and the gas spray hole is arranged on the oblique upper side of the trumpet-shaped burner head.

[0026] The beneficial effects of the present invention are:

[0027] Based on the air and fuel staging technology, the present invention integrates the air-flue gas premixing technology and the burner manufactured by the air-fuel premixing technology. Compared with the low-nitrogen burner using the IFGR (internal flue gas circulation) technology, it can further reduce the emission of nitrogen oxides and achieve ultra-low nitrogen emissions. Specifically:

[0028] 1. By controlling the mixing ratio of the central gas pipe, the combustion temperature can be made lower than the theoretical combustion temperature and lower than the starting temperature of thermal nitrogen oxide generation, thereby reducing the amount of nitrogen oxide generated.

[0029] 2. By controlling the flow rate of the gas nozzles of the surrounding gas pipes so that the mixed air coefficient is adjustable and less than 1, the combustion temperature can be lower than the theoretical combustion temperature and lower than the starting temperature of thermal nitrogen oxide generation, thereby reducing the amount of nitrogen oxide generated.

[0030] 3. The flue gas guide assembly introduces combustion flue gas to form a flue gas and air mixed flow, which forms a reducing atmosphere around the combustion head, thereby further reducing the generation of nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a side cross-sectional schematic diagram of the present invention installed on a combustion chamber.

[0032] Figure 2 It is a schematic diagram of the first half of the present invention.

[0033] Figure 3 It is a state diagram of the flow effects of air, fuel gas and combustion flue gas in the present invention.

[0034] Explanation of the accompanying figures: 1. Outer duct; 2. Mounting plate; 3. Combustion-supporting air port; 4. Burner shell; 5. Surrounding gas main pipe; 6. Central gas pipe; 7. Adjustment device; 8. Surrounding gas pipe; 9. Primary air duct; 10. Gas nozzle; 11. Guide port; 12. Suction chamber; 13. Mixing tube; 14. Swirl disk; 15. Combustion head; 16. Burner outer ring duct; 17. Smoke guide port; 18. Reduced diameter connecting pipe. DETAILED DESCRIPTION

[0035] See also Figure 1-3 As shown, the present invention relates to a compact premixed ultra-low nitrogen combustion device, which is arranged on the outer wall (furnace wall) of the combustion chamber. The compact premixed ultra-low nitrogen combustion device comprises: an outer guide tube 1, a burner shell 4, a regulating device 7, a primary air duct 9 and a central gas pipe 6, wherein:

[0036] An outer conduit 1, one end of which is inserted into the combustion chamber and the other end of which is connected to the burner housing 4; the outer conduit 1 is used to introduce secondary air A21 and flue gas C into the combustion chamber;

[0037] The burner housing 4 is provided with a combustion-supporting air port 3, and the combustion-supporting air enters the burner housing 4 through the combustion-supporting air port 3 and is divided into primary air A1 and secondary air A2; wherein the gas of the primary air A1 and the secondary air A2 is both air;

[0038] The primary air duct 9 passes through the outer duct 1, and the regulating device 7 is used to regulate the air volume of the primary air A1 entering the primary air duct 9;

[0039] The central gas pipe 6 is inserted into the primary air duct 9, and a trumpet-shaped burner head 15 is provided at the end of the central gas pipe 6. A gas spray hole is provided on the hypotenuse of the trumpet-shaped burner head 15. The gas is injected into the primary air duct 9 at high speed from the gas spray hole to realize gas-air premixing; a swirl disk 14 is provided at the end of the primary air duct 9, and the swirl disk 14 is adjacent to the trumpet-shaped burner head 15; the premixed gas and air are injected into the furnace at high speed through the swirl disk 14 for combustion.

[0040] The compact premixed ultra-low nitrogen combustion device also includes an air intake chamber 12, a mixing tube 13 and a plurality of surrounding gas pipes 8, one end of the mixing tube 13 is inserted into the combustion chamber (also called the furnace), and the other end of the mixing tube 13 is connected to the air intake chamber 12, and the air intake chamber 12 is provided with a guide port 11;

[0041] A plurality of the surrounding gas pipes 8 are evenly distributed on the outer circle of the primary air duct 9, and a gas nozzle 10 with a reduced diameter is provided at the front end of the surrounding gas pipe 8, and the gas nozzle 10 is inserted into the air intake chamber 12; the gas is ejected from the gas nozzle 10 to the air intake chamber 12 as an ejection medium, and a negative pressure is caused in the air intake chamber 12 due to the rapid flow of the medium, so that the surrounding air A22 is sucked in a large amount through the guide port 11 and quickly mixed with the gas, and the mixed gas and air are ejected into the furnace at a high speed through the mixing pipe 13 for combustion;

[0042] In the above solution, the gas nozzle 10 with a reduced diameter can make the airflow in the mixing tube 13 flow quickly.

[0043] It should be noted that the surrounding gas pipe 8 and the mixing pipe 13 form a whole that penetrates the outer conduit 1 .

[0044] The outlet of the outer duct 1 is connected with a reducing connecting pipe 18, and the reducing connecting pipe 18 is connected with the burner outer ring duct 16. A smoke guide port 17 is provided between the reducing connecting pipe 18 and the burner outer ring duct 16. The secondary air A21 forms a high-speed air flow at the outlet of the reducing connecting pipe 18, causing negative pressure at the smoke guide port 17, so that the flue gas C around the combustion chamber is sucked in a large amount and quickly mixed with the air, realizing premixing of flue gas and air, and the premixed mixed gas is injected into the furnace at a high speed to participate in combustion.

[0045] It should be noted that the secondary air A2 can be divided into secondary air A21 and secondary air A22 according to the different positions through which it flows. The secondary air A21 is located in the reducing connecting pipe 18 , and the secondary air A22 is located around the suction chamber 12 .

[0046] Furthermore, the compact premixed ultra-low nitrogen combustion device also includes a mounting plate 2, and the outer conduit 1 is fixed to the outer wall of the combustion chamber through the mounting plate 2.

[0047] Furthermore, the compact premixed ultra-low nitrogen combustion device also includes an ambient gas main pipe 5 , which is connected to the plurality of ambient gas pipes 8 .

[0048] Furthermore, the flow rate of the central gas pipe 6 accounts for 10%-15% of the total gas volume of the entire device, and the flow rate of the surrounding gas main pipe 5 accounts for 85%-90% of the total gas volume of the entire device.

[0049] Working principle:

[0050] like Figure 3 As shown, the combustion-supporting air A is divided into primary air A1 and secondary air A2 by the regulating device 7 in the burner shell 4; the primary air forms a primary air flow A1 in the primary air duct 9, and the gas in the central gas pipe 6 forms a gas flow B1. The gas flow B1 is injected into the primary air flow A1 at high speed from the gas nozzle, and the two gases are mixed into A1+B1 and then injected into the combustion chamber at high speed through the swirl disk 14. By controlling the proportion of the primary air A1, the combustion temperature can be made lower than the theoretical combustion temperature and lower than the starting temperature of thermal nitrogen oxide generation. At the same time, the high-speed swirling combustion gas can sweep the combustion flue gas around the combustion chamber, which can further reduce the amount of nitrogen oxide generated.

[0051] The gas in the surrounding gas pipe 8 forms a gas flow B2, and forms a high-speed jet at the reduced-diameter gas nozzle 10, sucking in a large amount of surrounding air A22. The two gases are mixed into A22+B2 and then injected into the combustion chamber at high speed through the mixing tube 13. Since the mixed air coefficient is less than 1, the combustion temperature is also lower than the theoretical combustion temperature and lower than the starting temperature of thermal nitrogen oxide generation. At the same time, the high-speed combustion gas can sweep the combustion flue gas around the combustion chamber, which can further reduce the generation of nitrogen oxides.

[0052] The secondary air flow A21 in the reducing connecting pipe 18 forms a high-speed air flow at the outlet of the reducing connecting pipe 18, and a large amount of combustion flue gas C introduced through the smoke guide port 17 is inhaled to form a flue gas and air mixed flow, which can form a reducing atmosphere between the combustion head 15 and the outlet of the mixing tube 13, thereby further reducing the generation of nitrogen oxides.

[0053] Advantages of the present invention:

[0054] Based on the air and fuel staging technology, the present invention integrates the air-flue gas premixing technology and the burner manufactured by the air-fuel premixing technology. Compared with the low-nitrogen burner using the IFGR (internal flue gas circulation) technology, it can further reduce the emission of nitrogen oxides and achieve ultra-low nitrogen emissions. Specifically:

[0055] 1. By controlling the mixing ratio of the central gas pipe 6, the combustion temperature can be made lower than the theoretical combustion temperature and lower than the starting temperature of thermal nitrogen oxide generation, thereby reducing the amount of nitrogen oxide generated.

[0056] 2. By controlling the flow rate of the gas nozzle 10 of the surrounding gas pipe 8 so that the mixed air coefficient is adjustable and less than 1, the combustion temperature can be lower than the theoretical combustion temperature and lower than the starting temperature of thermal nitrogen oxide generation, thereby reducing the amount of nitrogen oxide generated.

[0057] 3. The flue gas guide assembly introduces the combustion flue gas to form a flue gas and air mixed flow, which forms a reducing atmosphere around the burner head 15, thereby further reducing the amount of nitrogen oxides generated.

[0058] The above implementation modes are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering and technical personnel in the field shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A compact premixed ultra-low nitrogen combustion device, which is arranged on the outer wall of the combustion chamber, characterized in that: The compact premixed ultra-low nitrogen combustion device comprises: an outer conduit, a burner shell, an adjusting device, a primary air duct, a central gas pipe and a plurality of surrounding combustion components, the burner shell is connected to the outer conduit, the adjusting device is arranged inside the burner shell, and the burner shell is provided with a combustion-supporting air port; wherein, An outer conduit, one end of which is inserted into the combustion chamber, and an outlet of the outer conduit is connected to a smoke guide assembly for introducing air and smoke into the combustion chamber; The primary air duct passes through the outer duct and is sleeved on the central gas pipe. A swirl disk is provided at the end of the primary air duct. A burner head adjacent to the swirl disk is provided at the front end of the central gas pipe. The burner head is provided with a gas spray hole. The gas is sprayed from the gas spray hole into a blowing pipe and premixed with air before being injected into the furnace for combustion. A plurality of peripheral combustion components penetrate the outer conduit and are evenly arranged on the periphery of the primary air duct, and the peripheral combustion components are used to premix the gas with the air and inject the premixed mixed gas into the furnace at a high speed for combustion; The surrounding combustion assembly includes an air intake chamber, a mixing tube and a plurality of surrounding gas pipes, one end of the mixing tube is inserted into the combustion chamber, the other end of the mixing tube is connected to the air intake chamber, and the air intake chamber is provided with a guide port; A plurality of the surrounding gas pipes are evenly distributed in the outer circle of the primary air duct, and the front ends of the surrounding gas pipes are provided with gas nozzles with reduced diameters, and the gas nozzles are inserted into the air intake chamber.

2. A compact premixed ultra-low nitrogen combustion device according to claim 1, characterized in that: The smoke guide assembly comprises a reduced diameter connecting pipe and a burner outer ring conduit connected to the reduced diameter connecting pipe, and a smoke guide port is arranged between the reduced diameter connecting pipe and the burner outer ring conduit.

3. A compact premixed ultra-low nitrogen combustion device according to claim 2, characterized in that: The compact premixed ultra-low nitrogen combustion device also includes a mounting plate, and the outer conduit is fixed to the outer wall of the combustion chamber through the mounting plate.

4. A compact premixed ultra-low nitrogen combustion device according to claim 3, characterized in that: The compact premixed ultra-low nitrogen combustion device also includes an ambient gas main pipe, which is connected to the plurality of ambient gas pipes.

5. A compact premixed ultra-low nitrogen combustion device according to claim 4, characterized in that: The flow rate of the central gas pipe accounts for 10%-15% of the total gas volume of the entire device, and the flow rate of the surrounding gas main pipes accounts for 85%-90% of the total gas volume of the entire device.

6. A compact premixed ultra-low nitrogen combustion device according to claim 1, characterized in that: The burner head is a trumpet-shaped burner head, and the gas spray hole is arranged on the oblique side of the trumpet-shaped burner head.

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