Targeted air distribution system of corner tangential boiler suitable for high-alkali coal

Abstract

The utility model relates to the field of boilers, in particular to a targeted air distribution system of a corner tangential boiler suitable for high-alkali coal. The targeted air distribution system comprises secondary air side wall air bellows, a wall type secondary air equal-pressure air bellows, a front and rear wall fire-facing side targeted air assembly, a front and rear wall fire-backing side targeted air assembly, a side wall fire-facing side targeted air assembly and a side wall fire-backing side targeted air assembly. The wall type secondary air isobaric air bellows are arranged on the front wall and the rear wall of the furnace body, a plurality of front and rear wall fire-facing side target air assemblies and a plurality of front and rear wall fire-backing side target air assemblies which are communicated with the wall type secondary air isobaric air bellows are arranged on the front wall and the rear wall of the furnace body from top to bottom respectively, and the wall type secondary air isobaric air bellows are arranged on the two side walls of the furnace body. And a plurality of side wall fire-facing side target air assemblies and a plurality of side wall fire-backing side target air assemblies which are communicated with the secondary air side wall air box are respectively arranged from top to bottom. The targeted air distribution system disclosed by the utility model can obviously reduce the coking risk of the high-alkali coal.

Description

TECHNICAL FIELD

[0001] The utility model relates to four corner tangential boiler technical field, concretely relates to a kind of four corner tangential boiler targeting air distribution system suitable for high alkali coal, and it is especially suitable for four corner tangential boiler with Zhundong coal, hailer lignite and other high alkali coal as fuel. BACKGROUND

[0002] Xinjiang Zhundong coalfield is the large-scale whole coalfield proved in China, and coal resource forecast reserve is as high as 390 billion tons.Zhundong mining area is rich in coal resources, and the coal content per unit area is large, the coal seam structure is relatively simple, the burial is shallow, and the coal quality is good.However, Zhundong coal belongs to high alkali coal, the ash fusion point is low, the sodium and potassium ion content in ash is high, it is easy to coke, and the coke fluidity is large, when the furnace temperature rises, it is melted into liquid state, and it flows from top to bottom, the soot blower cannot work, the flowing coke covers the heating surface, and the phenomena such as covering the nozzle often occur, and the final result is to stop the furnace and clean the coke, which affects the operation of the unit.

[0003] In order to solve the above problems, the appropriate combustion air is sent to the reasonable position, and the effective utilization efficiency of the combustion air entering the furnace is improved.Therefore, how to reduce the coking risk of high alkali coal by the boiler targeting air distribution system is a problem to be solved at present. UTILITY MODEL CONTENT

[0004] In order to reduce the coking risk of high alkali coal, the utility model provides a kind of four corner tangential boiler targeting air distribution system suitable for high alkali coal, and it is especially suitable for four corner tangential boiler with Zhundong coal, hailer lignite and other high alkali coal as fuel.

[0005] In order to achieve the above purpose, the utility model provides a kind of targeting air distribution system of four corner tangential boiler, including secondary air side wall air box, wall type secondary air equal pressure air box, front and back wall fire side targeting air component, front and back wall back fire side targeting air component, side wall fire side targeting air component and side wall back fire side targeting air component, the secondary air side wall air box is arranged on the two side walls of furnace body, the wall type secondary air equal pressure air box is arranged on the front and back wall of furnace body, and a plurality of front and back wall fire side targeting air components and front and back wall back fire side targeting air components are arranged on the front and back wall of furnace body from top to bottom and communicated with the wall type secondary air equal pressure air box, and a plurality of side wall fire side targeting air components and side wall back fire side targeting air components are arranged on the two side walls of furnace body from top to bottom and communicated with the secondary air side wall air box.

[0006] Further, the number of layers of the front and back wall fire side targeting air component, the front and back wall back fire side targeting air component, the side wall fire side targeting air component and the side wall back fire side targeting air component is 5-7 layers, preferably 6 layers.

[0007] Further, the targeting air nozzle of each layer is arranged at 1 / 4-1 / 3 length of the corner.

[0008] Further, the fire-side target air jet and the backfire-side target air jet of each layer are 4.

[0009] Further, the fire-side target air jet angle α = 60-80°, for example 65°, 70°, 75°; the backfire-side target air jet angle β = 70-90°, for example 75°, 80°, 85°.

[0010] Further, the fire-side target air jet and the backfire-side target air jet are evenly distributed in the vertical direction between the B layer burner and the overfire air layer.

[0011] Further, the fire-side target air jet and the backfire-side target air jet have the same diameter of the tangent circle formed by the secondary air.

[0012] Further, the fire-side target air jet and the backfire-side target air jet are convergent nozzles.

[0013] Further, the height-width ratio of the fire-side target air jet and the backfire-side target air jet is 5-7:1, for example 6:1.

[0014] Further, the secondary air side wall air box and the wall type secondary air isobaric air box are communicated through the connecting pipeline, and the front and back wall fire-side target air assembly, the front and back wall backfire-side target air assembly, the side wall fire-side target air assembly and the side wall backfire-side target air assembly all take air from the secondary air side wall air box.

[0015] Further, the front and back wall fire-side target air assembly and the front and back wall backfire-side target air assembly take air from the burner air box, and the side wall fire-side target air assembly and the side wall backfire-side target air assembly take air from the secondary air side wall air box.

[0016] Overall, compared with the prior art, the target air distribution system of the utility model mainly has the following technical advantages:

[0017] The target air distribution system of the utility model increases the nozzle layer number, and each layer is provided with a fire-side target air jet and a backfire-side target air jet, that is, the number of nozzles of each layer is increased, the target air volume is increased, and the target air volume accounts for about 40% of the secondary air volume; after the target air system is increased, the secondary air and the overfire air nozzles of the corresponding area are reduced, and the differential pressure of the secondary air chamber is kept unchanged; by selecting appropriate target air nozzle necking ratio and height-width ratio, the jet velocity is higher and the momentum is larger under the condition of the same air volume. Therefore, the target air distribution system of the utility model can significantly reduce the risk of boiler heating surface coking. BRIEF DESCRIPTION OF DRAWINGS

[0018] The following drawings are only intended to illustrate and explain the utility model, and do not limit the scope of the utility model. Among them:

[0019] Figure 1 is a three-dimensional schematic view of the targeted air distribution system according to an embodiment of the present application;

[0020] Figure 2 is a planar arrangement schematic view of the nozzle of the targeted air distribution system according to an embodiment of the present application;

[0021] Figure 3 is a structural schematic view of the targeted air distribution assembly according to an embodiment of the present application;

[0022] Figure 4 is an appearance of the targeted air distribution assembly according to an embodiment of the present application;

[0023] Figure 5 is a tangent circle change schematic view before and after the targeted air distribution system according to an embodiment of the present application is applied. DETAILED DESCRIPTION

[0024] The present application will be further described below in conjunction with embodiments. The following embodiments are only used to help understand the present application. It should be noted that, for those skilled in the art, without departing from the principle of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0025] In the description of the present application, it is intended that the specific features, structures or parameters, steps, etc. described in the embodiments are at least contained in the embodiments according to the present application. Therefore, in the description of the present application, if the terms such as "according to an embodiment of the present application", "in an embodiment", etc. are used, they are not used to specifically refer to the same embodiment, and if the terms such as "in another embodiment", "according to different embodiments of the present application", "according to another embodiment of the present application", etc. are used, they are also not used to specifically refer to the features mentioned in the specific different embodiments. Those skilled in the art should understand that the specific features, structures or parameters, steps, etc. disclosed in one or more embodiments of the present application can be combined in any suitable manner.

[0026] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] The inventor of the utility model through a large number of researches considers that the reasons for the problems existing in the current burning Zhundong coal may have the following aspects: (1) the air distribution is not accurate enough, the coal powder burns in advance, and a local high-temperature zone is easily formed at the outlet of the burner, leading to coking and flow coking in the corner area of the boiler; (2) the proportion of overfire air is too large, and the combustion at the overfire air position is too intense, which is easy to coke; (3) the unit runs for a long time, the secondary air cutting circle direction is not accurate, the flow field is chaotic, the wall is easy to be brushed, the local ash deposition is serious, and with the passage of time, the ash deposition melts into flow coking; (4) when the coal supply increases, the unit load increases, the furnace temperature rises, the local part in the furnace reaches above the ash melting point, the coke starts to flow and accumulate, the coking amount increases, which affects the heat exchange of the heating surface, and further promotes the rise of the furnace temperature, forming a vicious cycle.

[0028] In view of the above reasons, the inventor improves the existing targeting system, so as to achieve the following purposes: (1) correct the flow field in the boiler, reduce the turbulent flow and air flow brushing wall, inhibit the ash deposition and coking near the wall, and reduce the coking risk of the heating surface of the boiler; (2) according to the characteristics of high volatile content and rapid combustion of Zhundong coal, the coal powder ignition distance is prolonged. The traditional arrangement of the secondary air nozzle is in the corner area, and the coal powder is mixed relatively quickly, the combustion in the corner area is intense, the local high temperature is easily generated in the corner area, the rapid coking occurs at the position, the primary and secondary air nozzles are blocked, and the coking is further aggravated; the targeting air system has a certain distance from the corner area, delays the ignition time, and reduces the coking risk; (3) the traditional arrangement of the wall-attached air has low air speed and small air volume, and the momentum is too low; for the Zhundong coal-fired boiler, it cannot play a role in protecting the water-cooled wall, and it is helpless for high-temperature corrosion; the targeting air installed on the furnace wall can play a cooling role, reduce the wall temperature of the water-cooled wall, and supplement oxygen to inhibit high-temperature corrosion.

[0029] As Figures 1-2As shown in the utility model, the four-corner tangential targeting air distribution system comprises a secondary air side wall air box 1, a wall-type secondary air equal pressure air box 2, front and back wall fire-side targeting air assemblies 3, front and back wall backfire-side targeting air assemblies 4, side wall fire-side targeting air assemblies 5 and side wall backfire-side targeting air assemblies 6. The secondary air side wall air box 1 is arranged on the two side walls of the furnace body, the wall-type secondary air equal pressure air box 2 is arranged on the front and back walls of the furnace body, and the wall-type secondary air equal pressure air box 2 is communicated with the secondary air side wall air box 1 through a connecting air duct 7. A plurality of front and back wall fire-side targeting air assemblies 3 and front and back wall backfire-side targeting air assemblies 4, which are communicated with the wall-type secondary air equal pressure air box 2, are arranged on the front and back walls of the furnace body from top to bottom. A plurality of side wall fire-side targeting air assemblies 5 and side wall backfire-side targeting air assemblies 6, which are communicated with the secondary air side wall air box 1, are arranged on the two side walls of the furnace body from top to bottom. The front and back wall fire-side targeting air assemblies 3, the front and back wall backfire-side targeting air assemblies 4, the side wall fire-side targeting air assemblies 5 and the side wall backfire-side targeting air assemblies 6 of each layer are located on the same horizontal plane. The end of each fire-side targeting air assembly is provided with a fire-side targeting air nozzle, and the end of each backfire-side targeting air assembly is provided with a backfire-side targeting air nozzle.

[0030] In an embodiment of the utility model, the four-corner tangential targeting air distribution system can further comprise corner-type targeting air assemblies arranged at the four corners of the furnace wall.

[0031] The targeting air nozzles of the utility model are arranged on the furnace wall, and the lowermost layer is the B layer combustor, and the uppermost layer is the lower part of the overfire air (OFA1) layer. Six layers are arranged on each of the four walls, the height difference h of the targeting air of each layer is between 1700-2400 mm, and there are 8 nozzles in each layer, that is, one fire-side targeting air nozzle and one backfire-side targeting air nozzle are arranged on each wall, and the distance between the position of each nozzle and the corner is 1 / 4-1 / 3 of the length of the furnace wall.

[0032] In Figure 1 In the embodiment of the utility model shown, the front and back wall fire-side targeting air assemblies 3, the front and back wall backfire-side targeting air assemblies 4, the side wall fire-side targeting air assemblies 5 and the side wall backfire-side targeting air assemblies 6 all take air from the secondary air side wall air box 1.

[0033] In another embodiment of the utility model, the side wall fire-side targeting air assemblies 5 and the side wall backfire-side targeting air assemblies 6 all take air from the secondary air side wall air box 1, and the front and back wall fire-side targeting air assemblies 3 and the front and back wall backfire-side targeting air assemblies 4 take air from the combustor air box.

[0034] As Figure 2 shown, the primary air imaginary tangential circle diameter is 500-800 mm, the targeting air imaginary tangential circle diameter is 1000-1200 mm, the fire-side targeting air and the backfire-side targeting air have the same tangential circle diameter, the fire-side targeting air jet angle α is 60-80°, and the backfire-side targeting air jet angle β is 70-90°.

[0035] As shown in Figure 3 , each targeting wind assembly comprises a targeting wind nozzle 8, a connecting mechanism 9, a square-round joint 10, a damper 11 and a circular pipe 12, wherein the connecting mechanism 9 is used to connect the targeting wind nozzle 8 and the square-round joint 10, the circular pipe 12 is located at the inlet end of the square-round joint 10, and the damper 11 is arranged inside the circular pipe 12. In an embodiment, the targeting wind assembly further comprises an operating handle 14, and the operating handle 14 is used to drive a connecting rod 13 to move so as to adjust the opening degree of the damper 11. In a preferred embodiment, the targeting wind assembly can further comprise a damper opening degree indicator 15, which is used to indicate the opening degree of the damper.

[0036] As shown in Figure 4 , the front end of the targeting wind nozzle 8 is in a tapered form, and the height-width ratio is 5-7:1, so that the wind speed can be increased. When the damper is fully opened, the secondary air wind chamber pressure is kept at 0.7 KPa, the cold-state wind speed of the targeting wind is 37 m / s, and the hot-state wind speed is about 75 m / s. The targeting wind amount accounts for 40% of the total secondary air wind amount.

[0037] As shown in Figure 5 , taking a self-provided power plant boiler of an aluminum plant in Wuciwan, Xinjiang as an example, according to the D-layer cold-state dynamic field test data, when the targeting wind is not opened, the tangential circle is inclined to the back wall (the area within the blue line); after the targeting wind is opened, the dynamic field tends to be balanced (the area within the red line).

[0038] During the operation process, the opening degree of the targeting wind damper is adjusted, and parameters such as the pre-boiler temperature, the furnace temperature and the nitrogen oxide are observed, and the results are shown in Table 1.

[0039] Before the furnace is ignited, the targeting wind damper is adjusted to the opening degree corresponding to No. 1 working condition, and in the process of increasing the load, the nitrogen oxide is reduced. Due to the fact that the wind speed of the newly-installed nozzle before and after the other dampers is relatively low, the tangential circle extends to the left and right sides of the front and back walls in the working conditions of No. 3 and No. 4 working conditions when the damper is fully opened. When the load is high, the targeting wind damper is adjusted to the opening degree of No. 5 and No. 6 working conditions, at this time, the amount of desuperheating water is small, the furnace temperature is low, the coking condition in the furnace is obviously improved, and the phenomena of flame brushing the wall and high-temperature corrosion are also suppressed. The mixing ratio of kaolin during the operation of the boiler is reduced from 100:10 to 100:9, and the economy of the unit operation is enhanced.

[0040] After the targeting wind system of the utility model is adopted, the overall resistance is reduced, the oxygen content during the operation is reduced, the total air volume and the flue gas volume are reduced, the current of the induced draft fan, the primary air fan and the air supply fan is reduced, the current of the air supply fan is reduced from 56A and 59A to below 38A, and the economy of the unit operation is enhanced.

[0041] The NO X concentration in the flue gas of the boiler is reduced from 197 / 200 mg / Nm 3 to 162 / 132 mg / Nm 3The ammonia water consumption is reduced from 256 kg / h to 188.66 kg / h. The secondary air box and the furnace differential pressure is reduced from 1 KPa to 0.7 KPa, increasing the secondary air system adjustment margin. The primary steam temperature is reduced from 438 ℃ to below 425 ℃, the desuperheating water amount is obviously reduced, the superheater desuperheating water amount is reduced by about 17 t / h, and the reheater desuperheating water amount is reduced by about 29 t / h. The fly ash and the slag carbon content are both reduced.

[0042] Table 1 boiler operation

[0043]

[0044]

[0045] The above-described specific embodiments further specifically describe the purpose, technical solutions and advantages of the present application. It should be understood that the above-described specific embodiments are merely examples of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A targeted air distribution system for a tangentially circular boiler, characterized in that: The furnace includes a secondary air sidewall bellows, a wall-type secondary air isobaric bellows, front and rear wall fire-facing targeted air components, front and rear wall back-fire targeted air components, sidewall fire-facing targeted air components, and sidewall back-fire targeted air components. The secondary air sidewall bellows are installed on the two side walls of the furnace body, and the wall-type secondary air isobaric bellows are installed on the front and rear walls of the furnace body. On the front and rear walls of the furnace body, from top to bottom, there are multiple front and rear wall fire-facing targeted air components and front and rear wall back-fire targeted air components that communicate with the wall-type secondary air isobaric bellows. On the two side walls of the furnace body, from top to bottom, there are multiple sidewall fire-facing targeted air components and sidewall back-fire targeted air components that communicate with the secondary air sidewall bellows.

2. The targeted air distribution system according to claim 1, characterized in that, The number of layers of the front and rear wall fire-facing side targeted air assembly, the front and rear wall fire-repellent side targeted air assembly, the side wall fire-facing side targeted air assembly, and the side wall fire-repellent side targeted air assembly is 5-7.

3. The targeted air distribution system according to claim 1, characterized in that, The fire-facing and back-fire-facing targeted air nozzles on each floor are located at a distance of 1 / 4 to 1 / 3 of the side length from the corner.

4. The targeted air distribution system according to claim 1, characterized in that, The angle of the targeted wind jet on the fire side is α = 60-80°; the angle of the targeted wind jet on the away side is β = 70-90°.

5. The targeted air distribution system according to claim 3, characterized in that, The fire-side targeted air nozzles and the back-fire-side targeted air nozzles are evenly distributed in the vertical direction between the B-layer burner and the burnout air layer.

6. The targeted air distribution system according to claim 3, characterized in that, The secondary air ejected from the fire-side targeted air nozzle and the back-fire-side targeted air nozzle forms a tangential circle with the same diameter.

7. The targeted air distribution system according to claim 3, characterized in that, The fire-facing and backfire-facing targeted air nozzles are tapered nozzles.

8. The targeted air distribution system according to claim 3, characterized in that, The aspect ratio of the fire-facing and backfire-facing targeted air nozzles is 5-7:

1.

9. The targeted air distribution system according to claim 1, characterized in that, The secondary air sidewall air box and the wall-type secondary air isobaric air box are connected by connecting pipes. The front and rear wall fire-facing side targeted air assembly, the front and rear wall fire-repellent side targeted air assembly, the sidewall fire-facing side targeted air assembly, and the sidewall fire-repellent side targeted air assembly all draw air from the secondary air sidewall air box.

10. The targeted air distribution system according to claim 1, characterized in that, The front and rear wall fire-facing side targeted air assembly and the front and rear wall back-fire side targeted air assembly draw air from the burner air box, while the side wall fire-facing side targeted air assembly and the side wall back-fire side targeted air assembly draw air from the secondary air side wall air box.

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