Multi-layer back flame type cyclone fluidization combustion efficient low-nitrogen layer combustion boiler

Abstract

The invention relates to the technical field of grate-fired boilers, and discloses a multi-layer back flame type cyclone fluidization combustion efficient low-nitrogen grate-fired boiler which comprises a boiler body, and the outer portion of the boiler body is fixedly connected with a boiler front wall membrane type wall. A first double-sided exposure water-cooled wall, a second double-sided exposure water-cooled wall and a third double-sided exposure water-cooled wall are sequentially arranged inside the boiler body; a first cyclone fluidized combustion area, a second cyclone fluidized combustion area and a third cyclone fluidized combustion area are sequentially arranged in the first double-sided exposure water-cooled wall, the second double-sided exposure water-cooled wall and the third double-sided exposure water-cooled wall. Through combination of a unique double-side exposure water-cooled wall division screen structure and a scientific air distribution technology, fuel gasification, staged combustion and low excess air coefficient operation are realized, generation and emission of nitrogen oxides are effectively controlled, the boiler coal type adaptability is high, the carbon content of slag is low, and the flue gas mixing effect and the flue gas prevention and dust removal effect in the boiler are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion boilers, and specifically to a multi-layer reverse-flame swirl fluidized combustion high-efficiency and low-nitrogen stoker boiler. Background Art

[0002] The state has been vigorously phasing out small-capacity coal-fired boilers and promoting the conversion of coal to gas, coal to electricity, and the coupling of gas, electricity, and air energy for multi-heat-source heating. High-efficiency and low-nitrogen combustion, ultra-low emissions, and collaborative comprehensive treatment have become the only way for coal-fired industrial boilers to continue to survive, carry out energy conservation and emission reduction transformations, and achieve sustainable development.

[0003] In order to control the emissions of atmospheric pollutants from stoker boilers, there was once a utility model patent of "A stoker boiler based on low-nitrogen combustion technology" (ZL201921058543.3), which combined "fuel staging combustion" with "air staging" and "recirculated flue gas staging" to achieve an original NOx emission of ≤200 mg / m3, which is close to the special emission limit for nitrogen oxides of newly built boilers in the "Emission Standard of Air Pollutants for Boilers" (GB 13271-2014). Its basic concept is pioneering, but the processability of the arch structure features and the effectiveness of the air distribution technology involved cannot match large-capacity stoker boilers, and it does not involve the principle and method of in-furnace fluidized combustion. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a multi-layer reverse-flame swirl fluidized combustion high-efficiency and low-nitrogen stoker boiler, which solves many drawbacks of traditional front and rear arch structure mode stoker furnaces and problems of air distribution technology.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: A multi-layer reverse-flame swirl fluidized combustion high-efficiency and low-nitrogen stoker boiler, including a boiler body, a boiler front wall membrane wall is fixedly connected to the outside of the boiler body, a first double-sided exposed water-cooled wall, a second double-sided exposed water-cooled wall, and a third double-sided exposed water-cooled wall are sequentially arranged inside the boiler body, and a first swirl fluidized combustion zone, a second swirl fluidized combustion zone, and a third swirl fluidized combustion zone are sequentially arranged inside the first double-sided exposed water-cooled wall, the second double-sided exposed water-cooled wall, and the third double-sided exposed water-cooled wall.

[0006] Preferably, a boiler rear arch is arranged inside the boiler body, and the first double-sided exposed water-cooled wall, the second double-sided exposed water-cooled wall, and the third double-sided exposed water-cooled wall together with the boiler rear arch form an adiabatic combustion zone, a main combustion zone, and an afterburning zone.

[0007] Preferably, the main combustion zone and the afterburning zone respectively form a first swirl fluidized combustion zone and a second swirl fluidized combustion zone through the upper edge of the first double-sided exposed water-cooled wall between the third double-sided exposed water-cooled wall and between the upper edges of the second double-sided exposed water-cooled wall.

[0008] Preferably, a downcomer flue in the furnace is provided inside the boiler body. The downcomer flue in the furnace is connected to the adiabatic combustion zone, and a third swirling fluidized combustion zone is formed between the front wall membrane water wall of the boiler and the first double-sided exposed water-cooled wall.

[0009] Preferably, a front-rising flue is provided on the left side inside the boiler body, and a furnace flue gas outlet window is provided at the top of the boiler body.

[0010] Preferably, a high-temperature economizer, a medium-temperature economizer, and a low-temperature economizer are sequentially arranged at the rear side outside the boiler body.

[0011] Preferably, a plurality of cross-beam type chain grate air supply chambers are arranged inside the adiabatic combustion zone, the main combustion zone, and the burnout zone.

[0012] Preferably, a plurality of selective non-catalytic reduction particle nozzles are arranged on both side walls of the front-rising flue where the flue gas temperature is in the range of 650°C to 800°C.

[0013] Preferably, a front-layer coal feeding device is installed on the left side outside the boiler body.

[0014] Working principle: After the fuel coal enters the furnace from the front-layer coal feeding device, it is quickly heated and raised in temperature in the adiabatic combustion zone. The coal layer is quickly gasified and dry-distilled in the high-temperature, low-oxygen, and fuel-rich reducing atmosphere where the air chamber in the moving firebed in the adiabatic combustion zone does not supply air or supplies weak air, forming a strong reducing atmosphere. There is enough time for the nitrogen oxides in the fuel to complete the pyrolysis process. The volatile nitrogen oxides generated by pyrolysis in the reducing atmosphere are directly reduced to molecular nitrogen, and the reducing atmosphere effectively inhibits the formation of fuel-type NOx. The gasification products are involved in the gas flow of the third swirling fluidized combustion zone as soon as they leave the coal layer, and part of the NOx generated in the main combustion zone is reduced to molecular nitrogen. After the ignited coking coal layer enters the main combustion zone, it continues to gasify and burn. The combustible gas and high-temperature combustion products generated by gasification tangentially enter the first and second swirling fluidized combustion zones and burn completely, greatly reducing the fly ash concentration in the flue gas. The high-temperature swirling gas flow enters the third swirling fluidized combustion zone from the downcomer flue in the furnace. A plurality of selective non-catalytic reduction particle nozzles are arranged on both side walls of the front-rising flue where the flue gas temperature is 650 - 800°C, further inhibiting the formation of fuel-type NOx, realizing the gasification of fuel and fuel staging, air staging combustion, operation with a low excess air coefficient, effectively controlling the generation and emission of nitrogen oxides, having a strong adaptability to boiler coal types, a low carbon content in the slag, strengthening the mixing effect of the flue gas in the furnace, having a good effect of eliminating smoke and dust in the furnace, eliminating the possibility of sticky ash on the convective heating surface, and injecting selective non-catalytic reduction particles in the range of 650 - 800°C suitable for the generation of nitrogen oxides in the furnace, achieving the comprehensive technical effects of ultra-low concentration emissions of soot and nitrogen oxides, and efficient energy-saving and clean combustion.

[0015] The present invention provides a multi-layered reverse-flame swirling fluidized combustion high-efficiency and low-nitrogen stoker boiler, which has the following beneficial effects: By combining the unique double-sided exposed water-cooled wall dividing screen structure of the boiler combustion chamber with scientific air distribution technology, the present invention realizes the gasification of fuel, fuel staging, and air staging combustion, operates with a low excess air coefficient, effectively controls the generation and emission of nitrogen oxides, has a strong adaptability to different coal types, a low carbon content in the slag, strengthens the flue gas mixing effect in the furnace, has a good effect of eliminating smoke and dust in the furnace, eliminates the possibility of sticky ash on the convective heating surface, and injects selective non-catalytic reduction particles in the temperature range of 650-800 °C suitable for the generation of nitrogen oxides in the furnace, achieving the comprehensive technical effects of ultra-low concentration emissions of soot and nitrogen oxides, high-efficiency energy conservation, and clean combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic internal structure diagram of the multi-layered reverse-flame swirling fluidized combustion high-efficiency and low-nitrogen stoker boiler of the present invention.

[0017] Wherein, 1. Coal feeding device in front of the furnace; 2. Membrane wall on the front wall of the boiler; 3. Upward flue in front of the furnace; 4. Third swirling fluidized combustion zone; 5. Adiabatic combustion zone; 6. First double-sided exposed water-cooled wall; 7. Downward flue in the middle of the furnace; 8. Second double-sided exposed water-cooled wall; 9. Second swirling fluidized combustion zone; 10. Smoke window at the outlet of the furnace flue gas; 11. Main combustion zone; 12. First swirling fluidized combustion zone; 13. Third double-sided exposed water-cooled wall; 14. Rear arch of the boiler; 15. Burnout zone; 16. Air supply chamber of the cross-beam type chain grate; 17. Low-temperature economizer; 18. Medium-temperature economizer; 19. High-temperature economizer; 20. Boiler body. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Embodiment: Please refer to the attached Figure 1 , the embodiment of the present invention provides a multi-layered reverse-flame swirling fluidized combustion high-efficiency and low-nitrogen stoker boiler, including: The boiler body 20 is externally fixedly connected with the front furnace wall membrane water wall 2. Inside the boiler body 20, a first double-sided exposed water-cooled wall 6, a second double-sided exposed water-cooled wall 8, and a third double-sided exposed water-cooled wall 13 are sequentially arranged. Inside the first double-sided exposed water-cooled wall 6, the second double-sided exposed water-cooled wall 8, and the third double-sided exposed water-cooled wall 13, a first swirling fluidized combustion zone 12, a second swirling fluidized combustion zone 9, and a third swirling fluidized combustion zone 4 are sequentially arranged to achieve multi-level and swirling flow high-efficiency combustion. A pre-furnace layered coal feeding device 1 is installed on the left side outside the boiler body 20 for feeding fuel coal into the furnace in layers.

[0020] Inside the boiler body 20, a boiler rear arch 14 is provided. The first double-sided exposed water-cooled wall 6, the second double-sided exposed water-cooled wall 8, and the third double-sided exposed water-cooled wall 13 together with the boiler rear arch 14 form an adiabatic combustion zone 5, a main combustion zone 11, and an afterburning zone 15. The main combustion zone 11 and the afterburning zone 15 respectively constitute the first swirling fluidized combustion zone 12 and the second swirling fluidized combustion zone 9 through the upper edge between the first double-sided exposed water-cooled wall 6 and the third double-sided exposed water-cooled wall 13 and between the upper edges of the second double-sided exposed water-cooled wall 8. Inside the adiabatic combustion zone 5, the main combustion zone 11, and the afterburning zone 15, a plurality of cross-beam type chain grate air chambers 16 are provided. These air chambers are in a non-air supply or gentle air state, keeping this area in a strong reducing atmosphere of high temperature, low oxygen, and rich fuel. The fuel coal rapidly heats up and undergoes dry distillation and gasification reactions in this atmosphere. The generated volatile matter pyrolyzes in the strong reducing environment, and the released nitrogen oxides are effectively reduced to molecular nitrogen, thus inhibiting the formation of fuel-type NOx. Some of the incompletely gasified coking coal layers then enter the main combustion zone 11 and continue to burn and gasify. The released high-temperature combustible gas and solid fuel particles enter the first swirling fluidized combustion zone 12 and the second swirling fluidized combustion zone 9 in a tangential manner. These two large swirling zones are respectively formed between the first double-sided exposed water-cooled wall 6 and the third double-sided exposed water-cooled wall 13, and between the second double-sided exposed water-cooled wall 8 and the third double-sided exposed water-cooled wall 13, and perform mixing and complete combustion under strong swirling flow conditions, reducing the fly ash concentration in the flue gas and increasing the burnout rate and thermal efficiency.

[0021] Inside the boiler body 20, there is a downcomer flue 7 in the furnace, which is connected to the adiabatic combustion zone 5. A third swirling fluidized combustion zone 4 is formed between the front wall membrane wall 2 of the boiler and the first double-sided exposed water-cooled wall 6. A front furnace upcomer flue 3 is provided on the left side inside the boiler body 20. A furnace flue gas outlet window 10 is provided at the top of the boiler body 20. On both side walls of the front furnace upcomer flue 3 where the flue gas temperature is in the range of 650°C to 800°C, a plurality of selective non-catalytic reduction particle nozzles are provided. The gas then enters the front furnace upcomer flue 3 provided on the left side inside the boiler body 20 and flows upward. In the temperature control area of 650°C to 800°C in this flue, a plurality of selective non-catalytic reduction SNCR particle nozzles are provided on both side walls for injecting reducing agents to react with the remaining NOx in the flue gas at the optimal temperature window to achieve a deep denitrification effect. The treated flue gas enters the furnace flue gas outlet window 10 provided at the top of the boiler from the front furnace upcomer flue 3, and then flows through the high-temperature economizer 19, medium-temperature economizer 18, and low-temperature economizer 17 provided at the rear of the boiler body 20 in sequence to recover waste heat to the greatest extent, thereby further improving the overall waste heat recovery efficiency of the boiler.

[0022] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Multilayer reverse-flame swirling flow combustion high-efficiency and low-nitrogen stoker boiler, including a boiler body (20), characterized in that, Outside the boiler body (20), a front wall membrane water wall (2) of the boiler is fixedly connected. Inside the boiler body (20), a first double-sided exposed water wall (6), a second double-sided exposed water wall (8), and a third double-sided exposed water wall (13) are sequentially arranged. Inside the first double-sided exposed water wall (6), the second double-sided exposed water wall (8), and the third double-sided exposed water wall (13), a first swirling fluidized combustion zone (12), a second swirling fluidized combustion zone (9), and a third swirling fluidized combustion zone (4) are sequentially arranged.

2. The multi-layer reverse-flame swirl-flow combustion high-efficiency and low-nitrogen stoker boiler according to claim 1, wherein, Inside the boiler body (20), a rear arch (14) of the boiler is arranged. The first double-sided exposed water wall (6), the second double-sided exposed water wall (8), and the third double-sided exposed water wall (13) together with the rear arch (14) of the boiler form an adiabatic combustion zone (5), a main combustion zone (11), and a burnout zone (15).

3. The multi-layer reverse-flame swirling flow combustion high-efficiency and low-nitrogen stoker boiler according to claim 2, characterized in that, The main combustion zone (11) and the burnout zone (15) respectively form a first swirling fluidized combustion zone (12) and a second swirling fluidized combustion zone (9) between the upper edge of the first double-sided exposed water wall (6) and the third double-sided exposed water wall (13) and between the upper edges of the second double-sided exposed water wall (8).

4. The multi-layer reverse-flame swirling-flow combustion high-efficiency and low-nitrogen stoker boiler according to claim 2, wherein Inside the boiler body (20), a middle-downward flue (7) is opened. The middle-downward flue (7) is connected to the adiabatic combustion zone (5). A third swirling fluidized combustion zone (4) is formed between the front wall membrane water wall (2) of the boiler and the first double-sided exposed water wall (6).

5. The multi-layer reverse-flame swirling-flow combustion high-efficiency and low-nitrogen stoker boiler according to claim 1, characterized in that, Inside the left side of the boiler body (20), a front-upward flue (3) is opened. On the top of the boiler body (20), a furnace flue gas outlet smoke window (10) is opened.

6. The multi-layer reverse-flame swirling flow combustion high-efficiency and low-nitrogen stoker boiler according to claim 1, wherein Outside the rear side of the boiler body (20), a high-temperature economizer (19), a medium-temperature economizer (18), and a low-temperature economizer (17) are sequentially arranged.

7. The multi-layer reverse-flame swirling-flow combustion high-efficiency and low-nitrogen stoker boiler according to claim 2, characterized in that, Inside the adiabatic combustion zone (5), the main combustion zone (11), and the burnout zone (15), a plurality of crossbeam type chain grate air supply chambers (16) are arranged.

8. The multi-layer reverse-flame swirl-flow combustion high-efficiency and low-nitrogen stoker boiler according to claim 5, characterized in that, On both side walls of the front-upward flue (3) where the flue gas temperature is in the range of 650 °C to 800 °C, a plurality of selective non-catalytic reduction particle spray nozzles are arranged.

9. The multi-layer reverse-flame swirling flow combustion high-efficiency and low-nitrogen stoker boiler according to claim 1, characterized in that, On the left side outside the boiler body (20), a front-layer coal feeding device (1) is installed.

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