CN100464118C - A Low NOx Swirl Combustion Device for Preventing High Temperature Corrosion - Google Patents

Abstract

A low NOx swirl combustion device for preventing high temperature corrosion relates to a combustion device. The purpose of the invention is to solve the problem of high-temperature corrosion while reducing NOx emissions in large pulverized coal boilers currently using swirl burners. The side wall OFA spout (4) of the present invention is arranged on the top of two side walls (9) in the furnace (1), and the center of the side wall OFA spout (4) lower side is where the powder swirl pulverized coal burner (2) is located. The area of the furnace (1) is the main combustion area (8), the area of the furnace (1) where the side wall OFA nozzle (4) and the swirl OFA nozzle (5) are located is the burnout area (6), and multiple center powder feeding swirls Pulverized coal burners (2) are arranged on the front and rear walls of the main combustion zone (8) side respectively, and the swirl OFA nozzles (5) are arranged on the front and rear walls of the burnout zone (6) side. When the pulverized coal of the present invention is burned, the generation of NOx can be further suppressed. For boilers burning bituminous coal, the emission of NOx can be reduced by more than 80%. The problem of high temperature corrosion occurs.

Description

A Low NOx Swirl Combustion Device for Preventing High Temperature Corrosion

technical field

The invention relates to a combustion device, in particular to a combustion device using pulverized coal as fuel.

Background technique

In the large-capacity power plant boilers operating in my country, the problem of high-temperature corrosion is becoming more and more serious. After the water-cooled wall undergoes high-temperature corrosion, the wall thickness and strength will decrease, which will easily cause tube burst and leakage, endangering the safe operation of the boiler. The main cause of high temperature corrosion is the presence of a reducing atmosphere near the corroded pipe wall. In recent years, with the continuous improvement of the country's NOx emission requirements for power plant boilers, many large-capacity power plant boilers have adopted OFA (overfired air) technology, which is to achieve air classification in the furnace and reduce NOx emissions. After the application of OFA (overfired air) technology, the main combustion area is in an oxygen-lean combustion state, showing a reducing atmosphere. While reducing NOx emissions, it intensifies the high-temperature corrosion of the water wall in the main combustion area. Swirl burners occupy a certain proportion in my country's power plant boilers and other pulverized coal applications. In my country's large pulverized coal boilers using swirling burners, while reducing NOx emissions, there are serious problems of high temperature corrosion, which endangers the safe operation of the boilers. Therefore, it is of great significance to study the low NOx swirling combustion technology to prevent high temperature corrosion for the development of my country's electric power industry and the entire national economy.

Contents of the invention

The purpose of the present invention is to provide a low NOx swirl combustion device that prevents high temperature corrosion in order to solve the problem of high temperature corrosion while reducing NOx emissions in large pulverized coal boilers that currently use swirl burners. The present invention is composed of a furnace, a plurality of central powder feeding swirl pulverized coal burners, a front wall, a side wall OFA nozzle, a swirl OFA nozzle, a burnout area, a rear wall, a main combustion area and two side walls; the front wall, A furnace is formed between the rear wall and the two side walls, and it is characterized in that the side wall OFA spout is arranged on the upper part of the two side walls in the furnace, and the center of the lower side of the side wall OFA spout feeds the furnace area where the pulverized coal burner is located. The main combustion zone, the side wall OFA nozzle and the furnace area where the swirling OFA nozzle is located is the burnout zone, and multiple central powder-feeding swirling pulverized coal burners are respectively installed on the front and rear walls of the main combustion zone, and the swirling OFA The nozzles are set on the front and rear walls on one side of the burnout area; the swirl OFA nozzles consist of a central secondary air duct, a cyclone, a damper baffle, a secondary air duct, a central secondary air nozzle, a secondary air nozzle, and an outer secondary air duct. It is composed of secondary air nozzle, external secondary air channel, external secondary air cyclone and external secondary air door baffle, the central secondary air channel is fixed on the front wall, rear wall or side wall, and the secondary air nozzle is set on On the side of the central secondary air nozzle of the central secondary air duct, a cyclone is fixed between the secondary air nozzle and the central secondary air duct, and the damper baffle is arranged outside the secondary air nozzle on the side of the cyclone. A secondary air channel is formed between the secondary air nozzle and the central secondary air channel, the outer secondary air nozzle is fixed on the outside of the secondary air nozzle, and the outer secondary air cyclone is fixed on the air inlet side of the outer secondary air nozzle On the secondary air nozzle, the outer secondary air damper baffle is fixed on the outer secondary air cyclone, and the outer secondary air channel is formed between the secondary air nozzle and the outer secondary air nozzle.

The beneficial effects of the present invention are: after adopting the technical scheme with OFA (overfired air), the excess air ratio in the main combustion zone is less than 1, and it is in an oxygen-lean combustion state, and the formation of fuel-type NOx in the main combustion zone is suppressed. However, the use of OFA (overfired air) technology will cause the excess air ratio in the main combustion zone to be less than 1, and it will be in an oxygen-poor combustion state, showing a reducing atmosphere, which will easily cause the side walls and front and rear walls of the area below the OFA (overfired air) nozzle High temperature corrosion occurs on the water wall. Opening OFA (overburned air) nozzles on both sides of the furnace, on the one hand, can reduce the formation of NOx, on the other hand, it can destroy the reducing atmosphere of the water-cooled walls on both sides of the area below the nozzle, and form an oxidizing atmosphere to further prevent the nozzle The occurrence of high-temperature corrosion of the water wall on both sides of the wall in the following areas. The central powder-feeding swirl pulverized coal burner sprays the concentrated pulverized coal flow into the furnace against the central part of the central recirculation zone of the burner. Therefore, the amount of pulverized coal passing through the central recirculation zone increases, and the passing time of pulverized coal increases, so that pulverized coal burns in a reducing atmosphere, which can effectively control the formation of fuel-type NOx. When OFA (overfired air) technology is used to make the excess air coefficient in the main combustion area less than 1, a stronger reducing atmosphere will be formed in the central recirculation zone, and when the pulverized coal is burned through the central recirculation zone, it will undergo a stronger reduction The formation of NOx can be further suppressed under a neutral atmosphere. The center-feeding swirling pulverized coal burner concentrates the concentrated pulverized coal flow at the center of the burner, so that no more pulverized coal will be thrown to the water-cooled wall of the side wall of the furnace due to the rotation of the secondary air, ensuring the main combustion The oxidizing atmosphere at the side walls of the area and the water walls at the front and rear walls can still ensure the air near the side walls and front and rear walls of the main combustion area even if the excess air ratio in the main combustion area is less than 1 due to the installation of OFA (overfired air) nozzles. The oxidizing atmosphere effectively prevents high-temperature corrosion of the side walls of the main combustion area and the water walls of the front and rear walls. Therefore, the use of low NOx swirling combustion devices to prevent high-temperature corrosion can completely solve the problem of high-temperature corrosion on both side walls and front and rear water-cooled walls in the area below the OFA (overfired air) nozzle.

Simply adopting the central powder-feeding swirl pulverized coal burner can ensure the oxidative atmosphere of the side walls of the main combustion area of the furnace and the water walls of the front and rear walls, and prevent the occurrence of high-temperature corrosion. At the same time, the central powder-feeding swirl pulverized coal burner sprays the concentrated pulverized coal flow into the furnace against the central part of the central recirculation zone of the burner. Therefore, the amount of pulverized coal passing through the central recirculation zone increases, and the passing time of pulverized coal increases, so that pulverized coal burns in a reducing atmosphere, and the formation of fuel-type NOx is suppressed to a certain extent. However, due to the high excess air ratio in the main combustion area, NOx emissions cannot be greatly reduced. Industrial tests have shown that for boilers burning bituminous coal, the NOx emissions can be reduced by using a center-feeding swirl pulverized coal burner. 20% or so. Simple use of OFA (overfired air) technology can achieve air classification in the furnace and effectively control the formation of NOx. For boilers burning bituminous coal, after using OFA (overfired air) technology, NOx emissions can be reduced by about 40% . However, the use of OFA (overfired air) technology will cause the excess air coefficient in the main combustion area to be less than 1, resulting in an oxygen-poor combustion state, resulting in high-temperature corrosion on the two sides of the OFA (overfired air) nozzle and the front and rear water walls, endangering the boiler safe operation. However, after adopting the low NOx swirl combustion device to prevent high temperature corrosion, and using OFA (overfired air) technology to make the excess air ratio in the main combustion zone less than 1, a stronger reducing atmosphere will be formed in the central recirculation zone, and the coal When the powder is burned through the central recirculation zone, the formation of NOx can be further suppressed. Therefore, the use of low-NOx swirl combustion devices to prevent high-temperature corrosion can greatly reduce the emission of NOx. For boilers burning bituminous coal, the emission of NOx can be reduced by more than 80%. At the same time, the use of low NOx swirling combustion devices to prevent high temperature corrosion can completely solve the problem of high temperature corrosion on both side walls and front and rear water walls below the OFA (overfired air) nozzle.

Description of drawings

Fig. 1 is a schematic view of the overall structure of the present invention, Fig. 2 is a schematic view of the structure of a powder swirl pulverized coal burner in the center, Fig. 3 is a schematic view of the structure of a swirl OFA (overburned air) nozzle, and Fig. 4 is a sectional view of A-A of Fig. 1 , FIG. 5 is a schematic structural diagram of Embodiment 4.

Detailed ways

Specific embodiment one: (see Fig. 1, Fig. 4) present embodiment is made up of furnace 1, a plurality of central powder-feeding swirl pulverized coal burners 2, front wall 3, side wall OFA (overburned air) spout 4, swirling flow OFA (overfire air) nozzle 5, burnout area 6, rear wall 7, main combustion area 8 and two side walls 9; a furnace 1 is formed between the front wall 3, rear wall 7 and two side walls 9, and the side The wall OFA (overfired air) nozzle 4 is arranged on the upper part of the two side walls 9 in the furnace 1, and the center of the lower side of the side wall OFA (overfired air) nozzle 4 is the area of the furnace 1 where the pulverized coal burner 2 is located. The main combustion zone 8, the side wall OFA (overfired air) nozzle 4 and the furnace 1 area where the swirl OFA (overfired air) nozzle 5 is located is the burnout zone 6, and multiple central powder feeding swirl pulverized coal burners 2 They are respectively arranged on the front and back walls of the main combustion zone 8 side, and the swirl OFA (overfired air) nozzles 5 are arranged on the front and rear walls of the burnout zone 6 side. All of the pulverized coal, primary air and most of the secondary air in this embodiment are burned in the main combustion zone 8 through the central powder-feeding swirl pulverized coal burner 2, and the remaining small part of the secondary air passes through the side wall OFA (overburned air) ) nozzle 4 and swirl OFA (overfired air) nozzle 5 enter the burnout zone 6 to participate in combustion.

Specific embodiment two: (see Fig. 2) the center of the present embodiment feeds powder swirl pulverized coal burner 2 by burner 2-2, three conical separating rings 2-3, outer swirler 2-4, Inner swirler 2-5, primary air duct 2-8, powder delivery pipeline 2-9, interior air door baffle 2-10, outer air door baffle 2-12, burner housing 2-13 and barrel-shaped partition Composed of plates 2-14, the burner housing 2-13 is fixedly connected to the front wall 3 or the rear wall 7, the primary air duct 2-8 is set at the center of the burner housing 2-13, and the primary air duct 2-8 is located at One end inside the burner housing 2-13 is the burner 2-2, the powder delivery pipeline 2-9 is arranged outside the burner housing 2-13, and the powder delivery pipeline 2-9 is fixedly connected with the primary air duct 2-8 , three conical separation rings 2-3 are arranged in the primary air duct 2-8, and the diameters of the three conical separation rings 2-3 decrease toward the direction of the burner 2-2, and each separation ring 2-3 The small-diameter end of the small-diameter end faces the burner 2-2, and a secondary air duct 2-11 is provided outside the primary air duct 2-8, and the interior of the secondary air duct 2-11 is separated by a barrel-shaped partition 2-14. The secondary air duct 2-7 and the outer secondary air duct 2-6 are respectively provided with an inner swirler 2-5 and an outer swirl in the inner secondary air duct 2-7 and the outer secondary air duct 2-6 Device 2-4, the air inlets of the inner secondary air duct 2-7 and the outer secondary air duct 2-6 are also provided with an inner damper damper 2-10 and an outer damper damper 2-12. Other compositions and connections are the same as in the first embodiment.

Specific embodiment three: (see Fig. 3) the swirl OFA (overburned air) nozzle 5 of the present embodiment is composed of a central secondary air duct 5-1, a swirler 5-3, a damper baffle plate 5-4, and a secondary air duct 5-1. The air channel 5-5 is composed of the central secondary air nozzle 5-6 and the secondary air nozzle 5-7. The central secondary air channel 5-1 is fixed on the front wall 3, the rear wall 7 or the side wall 9, and the secondary air The spout 5-7 is arranged on the side of the central secondary air spout 5-6 of the central secondary air duct 5-1, and a cyclone 5 is fixed between the secondary air spout 5-7 and the central secondary air duct 5-1 -3, the damper baffle plate 5-4 is arranged on the outside of the secondary air nozzle 5-7 on one side of the cyclone 5-3, and a secondary air outlet 5-7 is formed between the secondary air outlet 5-7 and the central secondary air duct 5-1. Secondary air duct 5-5. The airflow entering the central secondary air duct 5-1 is a straight jet, and the air entering the secondary air duct 5-5 is rotated after passing through the cyclone 5-3. Enter the furnace through the secondary air nozzle 5-7. The secondary air in the center is a straight jet, which can ensure the rigidity of the jet, prolong the jet flow, and achieve a better filling degree in the furnace; the rotating secondary air produces a larger expansion angle, which increases the contact between the overburned air and the high-temperature flue gas At the same time, the rotation of the secondary air enhances the turbulence of the airflow in the burnout zone, achieving better mixing of high-temperature flue gas and OFA (overfire air), so that the unburned fuel in the main combustion zone can be fully burned up. Other compositions and connections are the same as in the first embodiment.

Specific embodiment four: (referring to Fig. 5) the difference between this embodiment and specific embodiment three is that the external secondary air nozzle 5-8, the external secondary air channel 5-9, the external secondary air cyclone 5 are added -10 and the outer secondary air damper baffle 5-11, the outer secondary air nozzle 5-8 is fixed on the outside of the secondary air nozzle 5-7, and the outer secondary air cyclone 5-10 is fixed on the outer secondary air nozzle 5-8 On the secondary air nozzle 5-7 on the air inlet side, the outer secondary air damper baffle plate 5-11 is fixed on the outer secondary air cyclone 5-10, the secondary air nozzle 5-7 and the outer secondary air Outer secondary air channels 5-9 are formed between the secondary air nozzles 5-8. The airflow entering the central secondary air passage 5-1 is a straight jet, and the secondary air enters the furnace through the secondary air passage 5-5 and the outer secondary air passage 5-9, and the secondary air damper baffle plate 5-4 and the outer secondary air passage 5-9 enter the furnace. The secondary air damper baffle plate 5-11 can adjust the ratio of the internal and external swirling secondary air, and the secondary air is rotated by the secondary air cyclone 5-3 and the external secondary air cyclone 5-10. The central secondary air is a straight jet, which can ensure the rigidity of the jet, prolong the jet flow, and achieve a better filling degree in the furnace; divide the rotating secondary air into inner and outer parts to adjust the ratio of the inner and outer secondary air, increasing The air volume of OFA (overburning air) further reduces NOx emissions, and at the same time, it can also generate a larger expansion angle, further increase the contact area between overburning air and high-temperature flue gas, and further enhance the disturbance of the airflow in the overburning area, realizing The high-temperature flue gas and OFA (overfired air) are better mixed, so the unburned fuel in the main combustion zone can be burned more fully. Other compositions and connections are the same as those in the third embodiment.

Claims (2)

1. low NOx vortex burning device that prevents high temperature corrosion, it is made up of burner hearth (1), a plurality of centers powder-feeding cyclone burner for pulverized coal (2), front wall (3), side wall OFA spout (4), eddy flow OFA spout (5), burning-out zone (6), back wall (7), main combustion zone (8) and two side walls (9); Front wall (3), form burner hearth (1) between back wall (7) and two side walls (9), it is characterized in that side wall OFA spout (4) is arranged on the top of two side walls (9) in the burner hearth (1), burner hearth (1) zone at side wall OFA spout (4) downside center powder-feeding cyclone burner for pulverized coal (2) place is main combustion zone (8), burner hearth (1) zone at side wall OFA spout (4) and eddy flow OFA spout (5) place is burning-out zone (6), a plurality of centers powder-feeding cyclone burner for pulverized coal (2) are separately positioned on the front-back wall of main combustion zone (8) one sides, and eddy flow OFA spout (5) is arranged on the front-back wall of burning-out zone (6) one sides; Eddy flow OFA spout (5) is by center secondary air duct (5-1), cyclone (5-3), air door baffle plate (5-4), secondary air duct (5-5), center overfire air port (5-6), overfire air port (5-7), outer overfire air port (5-8), outer secondary air channel (5-9), outer secondary wind cyclone (5-10) and outer secondary wind air door baffle plate (5-11) are formed, center secondary air duct (5-1) is fixed on front wall (3), on back wall (7) or the side wall (9), overfire air port (5-7) is arranged on center overfire air port (5-6) side of center secondary air duct (5-1), be fixed with cyclone (5-3) between overfire air port (5-7) and the center secondary air duct (5-1), air door baffle plate (5-4) is arranged on the outside of the overfire air port (5-7) of cyclone (5-3) side, form secondary air duct (5-5) between overfire air port (5-7) and the center secondary air duct (5-1), outer overfire air port (5-8) is fixed on the outside of overfire air port (5-7), outer secondary wind cyclone (5-10) is fixed on the overfire air port (5-7) of outer overfire air port (5-8) air intake one side, outer secondary wind air door baffle plate (5-11) is fixed on the outer secondary wind cyclone (5-10), forms outer secondary air channel (5-9) between overfire air port (5-7) and the outer overfire air port (5-8).

2. a kind of low NOx vortex burning device that prevents high temperature corrosion according to claim 1, it is characterized in that center powder-feeding cyclone burner for pulverized coal (2) is by nozzles (2-2), the eseparation ring of three tapers (2-3), outer cyclone (2-4), interior cyclone (2-5), an airduct (2-8), pulverized coal feed pipe (2-9), interior air door baffle plate (2-10), outer damper plate (2-12), burner shell (2-13) and barrel-shaped dividing plate (2-14) are formed, burner shell (2-13) is fixedlyed connected with front wall (3) or back wall (7), an airduct (2-8) is arranged on the center of burner shell (2-13), the end that an airduct (2-8) is positioned at burner shell (2-13) is nozzles (2-2), pulverized coal feed pipe (2-9) is arranged on the outside of burner shell (2-13), pulverized coal feed pipe (2-9) is fixedlyed connected with an airduct (2-8), be provided with the eseparation ring (2-3) of three tapers in the airduct (2-8), the eseparation ring of three tapers (2-3) reduces successively towards nozzles (2-2) direction diameter, and the smaller diameter end of each eseparation ring (2-3) is towards nozzles (2-2), be provided with secondary air duct (2-11) in the outside of an airduct (2-8), be divided into interior secondary air duct (2-7) and outer secondary air duct (2-6) by barrel-shaped dividing plate (2-14) in the secondary air duct (2-11), interior secondary air duct (2-7) and outside be respectively arranged with in the secondary air duct (2-6) interior cyclone (2-5) and outside cyclone (2-4), interior secondary air duct (2-7) and outside the air inlet place of secondary air duct (2-6) also be provided with in air door baffle plate (2-10) and outside damper plate (2-12).

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