A sludge harmless low-nitrogen combustion system and method integrated with biogas combustion

Abstract

A sludge harmless low-nitrogen combustion system and method integrated with biogas combustion, the system includes a natural gas pipeline, a biogas generating pool, a flow concentration detection device, a biogas natural gas mixing chamber, a biogas header, an ignition probe, a primary air duct, a sludge hot air channel and a central air duct, a central gas spray gun and an auxiliary gas spray gun are arranged inside the central air duct, a central gas header is arranged at the inlet of the gas spray gun, a V-shaped nozzle is arranged at the outlet, the biogas header is connected to the biogas annular channel, an annular water-cooled orifice plate is arranged at the end of the annular channel, and a circle of air nozzles are arranged circumferentially on the outer layer of the combustion chamber. The present invention utilizes fuel and air staged combustion, flue gas reflux, balanced combustion and water-cooled combustion technology, aiming to achieve full utilization of biogas, low-nitrogen combustion of biogas and natural gas and harmless treatment of sludge.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-low nitrogen and harmless clean combustion of chemicals, and relates to a sludge harmless low-nitrogen combustion system and method integrated with biogas combustion. Background Art

[0002] With the acceleration of urbanization and the improvement of sewage treatment rates, the production of sludge is increasing day by day. Sludge has the characteristics of large production volume, instability, easy corruption, foul odor, and contains toxic and harmful substances such as parasite eggs, pathogenic microorganisms and heavy metals. If it is not properly and scientifically treated and disposed of, it will cause serious secondary pollution to the environment. In recent years, the incineration method for treating sludge has made great progress. Compared with other methods, the incineration method has the following outstanding advantages: (1) It can completely carbonize organic matter and minimize the volume and weight of sludge; (2) The processing speed is fast; (3) It can be incinerated on site without long-distance transportation; (4) Energy can be recovered for power generation and heating; (5) It occupies a small area and has a high level of automation. Therefore, how to effectively and harmlessly burn sludge has become a hot topic.

[0003] At the same time, with the rapid development of economy, energy consumption is growing rapidly. People are beginning to look for and use renewable energy to replace traditional energy. my country encourages and attaches importance to the development of unconventional natural gas and biomass gas. Biogas, as a typical biomass gas, is fermented from plants such as platycodon and feces. Its main components are methane and carbon dioxide. At present, biogas is mainly used for civil cooking and lighting, direct power generation of industrial power, etc. Compared with natural gas, it has the characteristics of wide sources, great development potential, recyclable, and large or small scale.

[0004] Existing low-nitrogen combustion technologies include staged combustion, premixed combustion, flue gas recirculation, water-cooled combustion, etc. Among them, full premixed combustion and flameless combustion are not suitable for high-power burners, while staged combustion, partial premixed combustion, water-cooled combustion and other technologies have become ways for high-power burners to achieve low-nitrogen combustion.

[0005] Since thermal nitrogen oxides are produced in the high-temperature combustion area, the most direct way to control the production of nitrogen oxides is to lower the temperature of the combustion chamber. The principle of water-cooled combustion is to use flowing water to carry away the heat in the combustion chamber to achieve low-nitrogen combustion; staged combustion technology is to achieve lean or rich combustion, and the temperature field distribution in the furnace is distributed by adjusting the fuel and air distribution, thereby avoiding the generation of local high temperatures and achieving the effect of reducing NOx generation. Summary of the invention

[0006] In order to achieve harmless treatment of sludge, fully utilize the heat of biogas, and realize low-nitrogen harmless clean combustion, the purpose of the present invention is to provide a sludge harmless low-nitrogen combustion system and method integrated with biogas combustion.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A sludge harmless low-nitrogen combustion system integrated with biogas combustion, comprising a biogas generator 2, a flow concentration detection device 1 connected to the biogas generator 2, the flow concentration detection device 1 outlet is divided into two paths, one path is directly connected to the biogas natural gas mixing chamber 4 inlet, and the other path is connected to the natural gas pipeline 0 outlet. One path is connected to the biogas natural gas mixing chamber 4 inlet through a first flow valve 3-1, and the natural gas pipeline 0 outlet is connected to a three-way joint 19 inlet through a second flow valve 3-1. The biogas natural gas mixing chamber 4 outlet is divided into two paths, one path is connected to the three-way joint 19 inlet through a third flow valve 3-3, and the other path is connected to a biogas header 5, and the three-way joint 19 outlet is connected to a burner 24; the burner 24 is sequentially arranged with a central gas header 10, a central air duct 12, and a sludge hot air outlet from the center to the outside. Channel 9, biogas annular channel 11 and primary air duct 8, the rear end of the burner 24 is connected to the combustion chamber 18; the front end of the central gas header 10 is connected to the outlet of the three-way joint 19, the center of the rear end is connected to the central gas spray gun 16, and the two sides are connected to the auxiliary gas spray guns 14; the front end of the biogas annular channel 11 is arranged with a biogas header 5, the biogas header is used to collect the biogas with stable components transported from the biogas natural gas mixing chamber 4, and the rear end of the biogas annular channel 11 is arranged with an annular water-cooled orifice plate 13, and the annular water-cooled orifice plate 13 is connected to the cooling water header 23; the periphery of the primary air duct 8 and the combustion chamber 18 is arranged with a water-cooled wall jacket 7, and the water-cooled wall jacket 7 is connected to the cooling water header 23; the ignition probe 6 is arranged at the center of the central gas spray gun 14 and the primary air duct 8, and can be extended back and forth to provide an ignition source during ignition.

[0009] The biogas generating pool 2 continuously generates biogas through the flow concentration detection device 1, which includes a biogas flow and methane concentration detection part and a logic operation part; the biogas flow and methane concentration detection part detects whether the methane concentration in the biogas reaches the methane content setting standard of 70%. If the methane concentration is insufficient, the logic operation part calculates the natural gas flow required to reach the standard concentration according to the biogas flow, and outputs an electrical signal to control the first flow valve 3-1 to pass the natural gas at this flow rate. The two gas paths merge into the biogas natural gas mixing chamber 4 to form biogas that can be continuously output and has a stable methane concentration, thereby achieving stable combustion of the biogas inside the burner.

[0010] The central gas spray gun 16 and the auxiliary gas spray gun 14 are arranged in a tube group type. The auxiliary gas spray gun 14 adopts a V-shaped nozzle 15. The gas sprayed by the auxiliary gas spray gun 14 can be mixed with air and then sprayed into the combustion chamber 18 for combustion, thereby achieving the effect of axial graded combustion and balanced combustion of the fuel.

[0011] During startup, the second flow valve 3-2 is opened and the third flow valve 3-3 is closed. During stable combustion, the second flow valve 3-2 is closed and the third flow valve 3-3 is opened, thereby realizing the conversion of the fuel of the auxiliary gas spray gun 14 and the central gas spray gun 16, achieving the purpose of using natural gas for stable ignition during startup and making full use of biogas during operation, and realizing the effect of fuel grading of biogas.

[0012] The central air duct 12 is provided with a swirl blade 20. The air in the central air duct 12 forms a swirl after passing through the swirl blade 20, and is fully mixed with the gas in the central gas spray gun 16 and the auxiliary gas spray gun 14. The flame swirl formed by the combustion is large, which can effectively suck the sludge particles sprayed from the sludge hot air channel 9, prolong the residence time of the sludge particles in the high-temperature flue gas, realize the combined classification of gas, sludge and fuel, improve the burnout rate and reduce NO X generate.

[0013] The sludge hot air channel 9 uses hot air to transport the sludge powder dried by flue gas, ensuring that the water content of the sludge is reduced and easy to burn; the sludge hot air channel 9 is arranged between the central air duct 12 and the biogas annular channel 11, and finally the sludge powder is sprayed into the combustion chamber 18 for combustion. Blunt bodies 21 are arranged circumferentially near the outlet of the sludge hot air channel 9. The sludge powder is moved toward the center by the blunt body to ensure the aggregation of the sludge powder, which is beneficial for it to be wrapped and burned by flue gas. Stabilizing teeth 22 are arranged at the outlet of the sludge hot air channel 9, which is beneficial for the stable combustion of the sludge powder.

[0014] The biogas natural gas mixing chamber 4 is connected to the biogas header 5 and a biogas annular channel 11 is arranged behind the biogas header 5. The end of the biogas annular channel 11 is isolated from the wall of the combustion chamber 18 to form a recirculation zone, which is conducive to the recirculation of smoke during combustion.

[0015] The end of the biogas annular channel 11 is provided with an annular water-cooling orifice plate 13. The biogas enters the primary air duct 8 through the small holes on the annular water-cooling orifice plate. After being ignited by the ignition probe 6, the flame formed in the combustion chamber 18 wraps the sludge powder again for combustion, further prolonging the residence time of the sludge powder in the central reduction zone, improving the burnout rate and reducing NO X generate.

[0016] A circle of air nozzles 17 are arranged around the combustion chamber 18 to continuously spray high-speed air into the combustion chamber, forming a layer of gaseous blunt body to prevent slagging on the wall after sludge combustion and to supplement the oxygen required for combustion.

[0017] The combustion method of the sludge harmless low-nitrogen combustion system integrated with biogas combustion, the biogas generating pool 2 continuously generates biogas through the flow concentration detection device 1, the biogas flow and methane concentration detection part of the flow concentration detection device 1 detects whether the methane concentration in the biogas reaches the methane content setting standard of 70%, if the methane concentration is insufficient, the logic operation part calculates the natural gas flow required to reach the standard concentration according to the biogas flow, and outputs an electrical signal to control the first flow valve 3-1 to pass the natural gas of the flow, the two gas paths merge into the biogas natural gas mixing chamber 4, the biogas natural gas mixing chamber 4 continuously outputs biogas with a stable methane concentration to pass into the biogas header 5;

[0018] At the beginning of the ignition stage, the second flow valve 3-2 is opened, and the natural gas from the natural gas pipeline 0 is passed into the central gas header 10 through the three-way joint 19 and then into the auxiliary gas spray gun 14 and the central gas spray gun 16. The air in the central air duct 12 forms a swirl through the swirl blades 20 and mixes with the gas sprayed from the auxiliary gas spray gun 14 and the central gas spray gun 16, and is ignited by the extended ignition probe 6 to form a flame in the combustion chamber 18; the biogas in the biogas header 5 is mixed with the air in the primary air channel 8 through the biogas annular channel 11 and the annular water-cooled orifice plate 13 in turn, and is ignited by the ignition probe 6 and burns in the combustion chamber 18; the sludge heat Sludge powder is fed into the air channel 9, and the sludge powder is gathered in a circle in the center by the action of the blunt body 21 and sprayed into the combustion chamber 18. Under the action of the stable combustion teeth 22, the stable combustion is wrapped by the recirculation zone formed by the central flame and the peripheral biogas flame to achieve full combustion of the sludge powder; the primary air channel 8 is connected to the water-cooled wall jacket 7 of the outer layer of the combustion chamber 18 and the annular water-cooled orifice plate 13 and the water-cooled header 23 to ensure low-nitrogen combustion and decomposition of dioxins. Air nozzles 17 are arranged around the periphery of the combustion chamber 18 to form a layer of air blunt bodies at the edge of the combustion chamber to prevent sludge combustion from slagging on the wall surface and to supplement the air required for combustion;

[0019] After ignition is completed and combustion is stable, the second flow valve 3-2 is closed, the third flow valve 3-3 is opened, and the central gas header 10 is switched to the biogas supplied by the biogas and natural gas mixing chamber 4, so as to achieve the purpose of biogas gas grading and natural gas saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the present invention.

[0021] Figure 2 It is a schematic diagram of the central gas header, central gas spray gun and auxiliary gas spray gun of the present invention.

[0022] Description of Reference Numerals

[0023] 0-natural gas pipeline; 1-flow concentration detection device; 2-biogas generating pool; 3-1-first flow valve; second 3-2 flow valve; 3-3-third flow valve; 4-biogas natural gas mixing chamber; 5-biogas header; 6-ignition probe; 7-water-cooled wall jacket; 8-primary air channel; 9-sludge hot air channel; 10-central gas header; 11-biogas annular channel; 12-central air duct; 13-annular water-cooled orifice plate; 14-auxiliary gas spray gun; 15-V-type nozzle; 16-central gas spray gun; 17-air nozzle; 18-combustion chamber; 19-tee joint; 20-swirl blade; 21-blunt body; 22-stable combustion teeth; 23-water-cooled header; 24-burner. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0025] like Figure 1 As shown, the present invention is a sludge harmless low-nitrogen combustion system with integrated biogas combustion, including a biogas generator 2, a flow concentration detection device 1 connected to the biogas generator 2, the outlet of the flow concentration detection device 1 is divided into two paths, one path is directly connected to the inlet of the biogas natural gas mixing chamber 4, and the other path is connected to the outlet of the natural gas pipeline 0. One path is connected to the inlet of the biogas natural gas mixing chamber 4 through a first flow valve 3-1, and the outlet of the natural gas pipeline 0 is connected to an inlet of a three-way joint 19 through a second flow valve 3-1. The outlet of the biogas natural gas mixing chamber 4 is divided into two paths, one path is connected to another inlet of the three-way joint 19 through a third flow valve 3-3, and the other path is connected to a biogas header 5, and the outlet of the three-way joint 19 is connected to a burner 24; the burner 24 is sequentially arranged with a central gas header 10, a central air duct 12, and a sewage gas mixing chamber 4 from the center to the outside. Mud hot air channel 9, biogas annular channel 11 and primary air duct 8, the rear end of burner 24 is connected to combustion chamber 18; the front end of the central gas header 10 is connected to the outlet of three-way joint 19, the center of the rear end is connected to the central gas spray gun 16, and the two sides are connected to auxiliary gas spray guns 14; the front end of the biogas annular channel 11 is arranged with a biogas header 5, the biogas header is used to collect the biogas with stable components transported from the biogas natural gas mixing chamber 4, and the rear end of the biogas annular channel 11 is arranged with an annular water-cooled orifice plate 13, and the annular water-cooled orifice plate 13 is connected to the cooling water header 23; the periphery of the primary air duct 8 and the combustion chamber 18 is arranged with a water-cooled wall jacket 7, and the water-cooled wall jacket 7 is connected to the cooling water header 23; the ignition probe 6 is arranged at the center of the central gas spray gun 14 and the primary air duct 8, and can be extended back and forth to provide an ignition source during ignition.

[0026] The burner 24 adopts a dual-tank supply method of gas and biogas. The central gas spray gun 16 and the auxiliary gas spray gun 14 are arranged in a pipe group. After the natural gas is sent into the central gas header 10, it is distributed to the auxiliary gas spray gun 14 and the central gas spray gun 16 pipes, and then flows out from several small tubes and mixes with the high-speed air flowing through, thereby improving the air / gas mixing condition and achieving the purpose of balanced combustion. A biogas header 5 is set for biogas to continuously and stably supply biogas.

[0027] like Figure 1 As shown, the biogas generating pool 2 continuously generates biogas through the flow concentration detection device 1, and the flow concentration detection device 1 includes a biogas flow and methane concentration detection part and a logic operation part; the biogas flow and methane concentration detection part detects whether the methane concentration in the biogas reaches the methane content setting standard of 70%, and if the methane concentration is insufficient, the logic operation part calculates the natural gas flow required to reach the standard concentration according to the biogas flow, and outputs an electrical signal to control the first flow valve 3-1 to pass the natural gas of the flow, and the two gases merge into the biogas natural gas mixing chamber 4 to form a biogas that can be continuously output and has a stable methane concentration, thereby achieving stable combustion of the biogas inside the burner.

[0028] like Figure 1 As shown, the sludge hot air channel 9 uses hot air to transport the sludge powder dried by flue gas, ensuring that the water content of the sludge is reduced and easy to burn; the sludge hot air channel 9 is arranged between the central air duct 12 and the biogas annular channel 11, and finally the sludge powder is sprayed into the combustion chamber 18 for combustion. Blunt bodies 21 are arranged circumferentially near the outlet of the sludge hot air channel 9. The sludge powder is moved toward the center by the blunt body to ensure the aggregation of the sludge powder, which is beneficial for it to be wrapped and burned by flue gas. Stabilizing teeth 22 are arranged at the outlet of the sludge hot air channel 9, which is beneficial for the stable combustion of the sludge powder.

[0029] like Figure 1 As shown, a three-way joint 19 is arranged in front of the gas manifold 10, which is respectively connected to the natural gas pipeline 0 and the biogas natural gas mixing chamber 4. When starting, the second flow valve 3-2 is opened and the third flow valve 3-3 is closed. When the combustion is stable, the second flow valve 3-2 is closed and the third flow valve 3-3 is opened, so as to realize the conversion of the fuel of the auxiliary gas spray gun 14 and the central gas spray gun 16, so as to achieve the purpose of using natural gas for stable ignition at startup and making full use of biogas during operation, and realize the effect of fuel grading of biogas.

[0030] like Figure 1As shown, the central air duct 12 has a swirl blade 20 inside. The air in the central air duct 12 forms a swirl after passing through the swirl blade 20, and is fully mixed with the gas in the central gas spray gun 16 and the auxiliary gas spray gun 14. The flame swirl formed by the combustion is large, which can effectively suck the sludge particles sprayed from the sludge hot air channel 9, prolong the residence time of the sludge particles in the high-temperature flue gas, realize the combined classification of gas, sludge and fuel, improve the burnout rate and reduce NO X generate.

[0031] like Figure 1 As shown, the biogas natural gas mixing chamber 4 is connected to the biogas header 5 and a biogas annular channel 11 is arranged behind the biogas header 5. The end of the biogas annular channel 11 is isolated from the wall of the combustion chamber 18 to form a recirculation zone, which is conducive to the recirculation of smoke during combustion.

[0032] like Figure 2 As shown, the outlet of the auxiliary gas spray gun 14 adopts a V-shaped nozzle 15, the central gas spray gun 16 forms the main flame, the auxiliary gas spray gun 14 and the primary air assist combustion at the periphery, and a central flue gas recirculation zone is formed between the two spray guns to preheat and dilute the air and fuel that have not yet undergone combustion reaction, which can effectively strengthen the combustion and stabilize the flame. At the same time, the flue gas recirculation makes the temperature distribution in the furnace more uniform, reduces the maximum temperature of the combustion chamber, and inhibits the formation of thermal NOx. At the same time, the flue gas recirculation entrains the sludge powder, increases its residence time in the combustion chamber, promotes its complete combustion, and is conducive to the decomposition of the dioxins produced when the sludge is burned to achieve the effect of harmless combustion.

[0033] like Figure 1 As shown, an annular water-cooled orifice plate 13 is arranged at the end of the biogas annular channel 11. The biogas enters the primary air duct 8 through the small holes on the annular water-cooled orifice plate and is ignited by the ignition probe 6 for combustion. The annular water-cooled orifice plate can effectively prevent backfire and reduce the combustion temperature, and control the generation of nitrogen oxides.

[0034] like Figure 1 As shown, a water-cooled wall jacket 7 is arranged on the periphery of the primary air duct 8 and the combustion chamber 18 to reduce the combustion temperature and control the combustion chamber temperature at about 1000°C. At this temperature, the generation of thermal nitrogen oxides is effectively suppressed, and dioxins generated by sludge combustion are also effectively decomposed.

[0035] like Figure 1 As shown, a circle of air nozzles 17 are arranged circumferentially around the combustion chamber 18 to continuously spray high-speed air into the combustion chamber, forming a layer of gaseous blunt body to prevent sludge from slagging on the wall after combustion and to supplement the oxygen required for combustion.

[0036] like Figure 1As shown, the combustion method of the sludge harmless low-nitrogen combustion system integrated with biogas combustion described in the present invention, the biogas generating pool 2 continuously generates biogas through the flow concentration detection device 1, the biogas flow and methane concentration detection part of the flow concentration detection device 1 detects whether the methane concentration in the biogas reaches the methane content setting standard of 70%, if the methane concentration is insufficient, the logic operation part will calculate the natural gas flow required to reach the standard concentration according to the biogas flow, and at the same time output an electrical signal to control the first flow valve 3-1 to pass the natural gas of the flow, the two gases merge into the biogas natural gas mixing chamber 4, the biogas natural gas mixing chamber 4 continuously outputs biogas with stable methane concentration to pass into the biogas header 5; at the beginning of the ignition stage, the second flow valve 3-2 is opened, the natural gas of the natural gas pipeline 0 is passed into the central gas header 10 through the three-way connector 19 and then into the auxiliary gas spray gun 14 and the central gas spray gun 16, the air in the central air duct 12 passes through the swirl blades 20 to form a swirl and is mixed with the gas sprayed from the auxiliary gas spray gun 14 and the central gas spray gun 16, and is ignited by the extended ignition probe 6, and in the combustion The flame is formed in the chamber 18; the biogas in the biogas header 5 is mixed with the air in the primary air channel 8 through the biogas annular channel 11 and the annular water-cooled orifice plate 13 in turn and ignited by the ignition probe 6 to burn in the combustion chamber 18; the sludge hot air channel 9 is fed with sludge powder, which is gathered in a circle in the center by the blunt body 21 and sprayed into the combustion chamber 18. Under the action of the stable combustion teeth 22, the stable combustion is wrapped by the reflux zone formed by the central flame and the peripheral biogas flame to achieve full combustion of the sludge powder; the primary air channel 8 and the water-cooled wall of the outer layer of the combustion chamber 18 The sleeve 7 and the annular water-cooled orifice plate 13 are connected to the water-cooled header 23 to ensure low-nitrogen combustion and decomposition of dioxins. Air nozzles 17 are arranged around the periphery of the combustion chamber 18 to form a layer of air blunt bodies at the edge of the combustion chamber to prevent slagging on the wall caused by sludge combustion and to supplement the air required for combustion. After ignition is completed and combustion is stable, the second flow valve 3-2 is closed and the third flow valve 3-3 is opened, and the central gas header 10 is changed to biogas supplied by the biogas natural gas mixing chamber 4 to achieve the purpose of biogas gas grading and saving natural gas.

[0037] In order to achieve ultra-low nitrogen and harmless combustion, the present invention mainly adopts the following measures:

[0038] (1) Staged combustion: The central gas is axially staged through the central gas spray gun 16 and the auxiliary gas spray gun 14. At the same time, the central gas and biogas form gas staged combustion. The biogas, natural gas and sludge powder form gas and solid staged combustion. At the same time, the air required for combustion is staged into the burner through the central air duct 12, the sludge hot air channel 9, the primary air duct 8 and the air nozzle 17 to achieve air staged combustion.

[0039] (2) Balanced combustion: The outlet of the auxiliary gas spray gun 14 is inside the outlet of the central air duct, and the air and gas can be mixed in the central air duct to achieve the purpose of balanced combustion.

[0040] (3) Flue gas recirculation: The outlet of the auxiliary gas spray gun 14 adopts a V-shaped nozzle 15, and the central gas spray gun 16 forms the main flame. The auxiliary gas spray gun 14 and the primary air assist combustion on the periphery, and a central flue gas recirculation zone is formed between the two spray guns to preheat and dilute the air and fuel that have not yet undergone a combustion reaction, which can effectively enhance combustion and stabilize the flame. Flue gas recirculation makes the temperature distribution in the furnace more uniform, reduces the maximum temperature of the combustion chamber, and inhibits the formation of thermal NOx. In the combustion chamber 18, the flue gas recirculation generated by the flames burning in the central gas pipeline and the annular biogas combustion pipeline can effectively entrain the sludge powder discharged from the sludge hot air pipeline between the two, increase the residence time of the sludge powder in the combustion chamber, and achieve full combustion of the sludge.

[0041] (4) Water-cooled combustion: The annular water-cooled orifice plate 13 and the water-cooled jacket 7 effectively reduce the combustion temperature and the combustion chamber temperature, control the combustion chamber temperature at about 1000°C, reduce the generation of thermal nitrogen oxides, and ensure that the dioxins generated during sludge combustion are effectively decomposed.

Claims

1. A sludge harmless low-nitrogen combustion system integrated with biogas combustion, characterized by: The invention comprises a biogas generating pool (2), a flow concentration detection device (1) connected to the biogas generating pool (2), the outlet of the flow concentration detection device (1) being divided into two paths, one of which is directly connected to the inlet of a biogas natural gas mixing chamber (4), and the other of which is connected to the outlet of a natural gas pipeline (0). One of which is connected to the inlet of the biogas natural gas mixing chamber (4) through a first flow valve (3-1), and the other of which is connected to the outlet of the natural gas pipeline (0) through a second flow valve (3-2). The outlet of the biogas natural gas mixing chamber (4) is divided into two paths, one of which is connected to the other inlet of the three-way joint (19) through a third flow valve (3-3), and the other of which is connected to a biogas header (5). The outlet of the three-way joint (19) is connected to a burner (24); the burner (24) is sequentially provided with a central gas header (10), a central air duct (12), a sludge hot air channel (9), a biogas annular channel (11) from the center to the outside. ) and a primary air duct (8), the rear end of the burner (24) is connected to the combustion chamber (18); the front end of the central gas header (10) is connected to the outlet of the three-way joint (19), the center of the rear end is connected to the central gas spray gun (16), and the two sides are connected to the auxiliary gas spray guns (14); the front end of the biogas annular channel (11) is arranged with a biogas header (5), the biogas header is used to collect biogas with stable components transported from the biogas natural gas mixing chamber (4), and the rear end of the biogas annular channel (11) is arranged with an annular water-cooled orifice plate (13), and the annular water-cooled orifice plate (13) is connected to the cooling water header (23); the periphery of the primary air duct (8) and the combustion chamber (18) is arranged with a water-cooled wall jacket (7), and the water-cooled wall jacket (7) is connected to the cooling water header (23); the ignition probe (6) is arranged at the center of the central gas spray gun (16) and the primary air duct (8), and can be extended forward and backward to provide an ignition source during ignition; The sludge hot air channel (9) uses hot air to transport the sludge powder that has been dried by flue gas, ensuring that the water content of the sludge is reduced and easy to burn; the sludge hot air channel (9) is arranged between the central air channel (12) and the biogas annular channel (11), and finally the sludge powder is sprayed into the combustion chamber (18) for combustion. Blunt bodies (21) are arranged circumferentially near the outlet of the sludge hot air channel (9). The sludge powder is moved toward the center by the blunt bodies, ensuring the aggregation of the sludge powder, which is conducive to its being wrapped by flue gas and burning. Stable combustion teeth (22) are arranged at the outlet of the sludge hot air channel (9), which is conducive to the stable combustion of the sludge powder. An annular water-cooling orifice plate (13) is arranged at the end of the biogas annular channel (11). The biogas enters the primary air duct (8) through the small holes on the annular water-cooling orifice plate. After being ignited by the ignition probe (6), the flame formed in the combustion chamber (18) wraps the sludge powder again for combustion, further prolonging the residence time of the sludge powder in the central reduction zone, improving the burnout rate and reducing NO X generate.

2. The sludge harmless low-nitrogen combustion system integrated with biogas combustion according to claim 1 is characterized by: The biogas generating pool (2) continuously generates biogas which passes through a flow concentration detection device (1). The flow concentration detection device (1) comprises a biogas flow and methane concentration detection part and a logic operation part. The biogas flow and methane concentration detection part detects whether the methane concentration in the biogas reaches a methane content setting standard of 70%. If the methane concentration is insufficient, the logic operation part calculates the natural gas flow required to reach the standard concentration according to the biogas flow, and outputs an electrical signal to control the first flow valve (3-1) to pass the natural gas at the flow rate. The two gases merge into a biogas and natural gas mixing chamber (4), forming biogas that can be continuously output and has a stable methane concentration, thereby achieving stable combustion of the biogas inside the burner.

3. The sludge harmless low-nitrogen combustion system integrated with biogas combustion according to claim 1 is characterized by: The central gas spray gun (16) and the auxiliary gas spray gun (14) are arranged in a tube group type, and the auxiliary gas spray gun (14) adopts a V-shaped nozzle (15). The gas sprayed by the auxiliary gas spray gun 14 can be mixed with air and then sprayed into the combustion chamber (18) for combustion, thereby achieving the effect of axial staged combustion and balanced combustion of the fuel.

4. The sludge harmless low-nitrogen combustion system integrated with biogas combustion according to claim 1 is characterized by: During startup, the second flow valve (3-2) is opened and the third flow valve (3-3) is closed. During stable combustion, the second flow valve (3-2) is closed and the third flow valve (3-3) is opened, so as to realize the conversion of the fuel of the auxiliary gas spray gun (14) and the central gas spray gun (16), so as to achieve the purpose of using natural gas for stable ignition during startup and making full use of biogas during operation, and realize the effect of biogas fuel grading.

5. The sludge harmless low-nitrogen combustion system integrated with biogas combustion according to claim 1 is characterized by: The central air duct (12) has a swirl blade (20) inside. The air in the central air duct (12) forms a swirl after passing through the swirl blade (20) and is fully mixed with the gas in the central gas spray gun (16) and the auxiliary gas spray gun (14). The flame formed by combustion has a large swirl degree, which can effectively entrain the sludge particles sprayed from the sludge hot air channel (9), prolong the residence time of the sludge particles in the high-temperature flue gas, realize the combined classification of gas, sludge and fuel, improve the burnout rate and reduce NO X generate.

6. The sludge harmless low-nitrogen combustion system integrated with biogas combustion according to claim 1, characterized in that: The biogas and natural gas mixing chamber (4) is connected to the biogas header (5) and a biogas annular channel (11) is arranged behind the biogas header (5). The end of the biogas annular channel (11) is isolated from the wall of the combustion chamber (18) to form a recirculation zone, which is conducive to the recirculation of smoke during combustion.

7. The sludge harmless low-nitrogen combustion system integrated with biogas combustion according to claim 1 is characterized by: A circle of air nozzles (17) are arranged around the outer periphery of the combustion chamber (18) to continuously spray high-speed air into the combustion chamber, forming a layer of gaseous blunt body to prevent sludge from slagging on the wall after combustion and to supplement the oxygen required for combustion.

8. A combustion method for a sludge harmless low-nitrogen combustion system integrated with biogas combustion according to any one of claims 1 to 7, characterized in that: The biogas generating pool (2) continuously generates biogas which passes through the flow concentration detection device (1). The biogas flow and methane concentration detection part of the flow concentration detection device (1) detects whether the methane concentration in the biogas reaches the methane content setting standard of 70%. If the methane concentration is insufficient, the logic operation part calculates the natural gas flow required to reach the standard concentration according to the biogas flow, and outputs an electrical signal to control the first flow valve (3-1) to pass the natural gas of the flow. The two gas paths merge into the biogas natural gas mixing chamber (4). The biogas natural gas mixing chamber (4) continuously outputs biogas with a stable methane concentration and passes it into the biogas header (5); At the beginning of the ignition phase, the second flow valve (3-2) is opened, and the natural gas from the natural gas pipeline (0) is introduced into the central gas header (10) through the three-way joint (19) and then introduced into the auxiliary gas spray gun (14) and the central gas spray gun (16). The air in the central air duct (12) forms a swirl through the swirl blades (20) and is mixed with the gas sprayed from the auxiliary gas spray gun (14) and the central gas spray gun (16), and is ignited by the extended ignition probe (6) to form a flame in the combustion chamber (18); the biogas in the biogas header (5) is mixed with the air in the primary air duct (8) through the biogas annular channel (11) and the annular water-cooled orifice plate (13) and is ignited by the ignition probe (6) in the combustion chamber (18). ) combustion; sludge powder is fed into the sludge hot air channel (9), and the sludge powder is gathered in a central circle by the action of the blunt body (21) and sprayed into the combustion chamber (18). Under the action of the stable combustion teeth (22), the stable combustion is wrapped in the recirculation zone formed by the central flame and the peripheral methane flame to achieve full combustion of the sludge powder; the primary air duct (8) is connected to the water-cooled wall jacket (7) of the outer layer of the combustion chamber (18) and the annular water-cooled orifice plate (13) and the cooling water header (23) to ensure low-nitrogen combustion and decomposition of dioxins. Air nozzles (17) are arranged around the periphery of the combustion chamber (18) to form a layer of air blunt bodies at the edge of the combustion chamber to prevent sludge combustion from slagging on the wall surface and to supplement the air required for combustion; After ignition is completed and combustion is stable, the second flow valve (3-2) is closed, the third flow valve (3-3) is opened, and the central gas header (10) is switched to biogas supplied by the biogas and natural gas mixing chamber (4), thereby achieving the purpose of biogas gas classification and natural gas saving.

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