Secondary air structure for biomass water-cooling vibrating grate boiler

Abstract

A secondary air structure for a biomass water-cooling vibrating grate boiler is arranged above a vibrating grate and comprises a front wall secondary air pipe set and a rear wall secondary air pipe set, the front wall secondary air pipe set and the rear wall secondary air pipe set are arranged on a hearth at the same time, secondary air of the front wall secondary air pipe set is jetted to the front middle portion and the rear portion of the vibrating grate, and secondary air of the rear wall secondary air pipe set is jetted to the rear portion of the vibrating grate. And secondary air of the rear wall secondary air pipe group is sprayed to the front part and the middle part of the vibration fire grate. According to the secondary air structure, the secondary air pipe sets are arranged on the front wall and the rear wall at the same time, the spraying angle is controlled, the secondary air structure can be suitable for the large-capacity biomass fire grate, air on the vibration fire grate can be better supplemented, biomass fuel can be burnt out on the vibration fire grate as much as possible, the loss of unburnt carbon is greatly reduced, and the energy consumption is reduced. And the device is suitable for large-capacity biomass fire grates.

Description

Technical Field

[0001] The invention relates to an air distribution structure, in particular to a secondary air structure for a biomass water-cooled vibrating grate boiler, and belongs to the technical field of biomass combustion. Background Art

[0002] Biomass is increasingly valued as a fuel for power generation and is developing towards large capacity. With the development of large capacity (boiler evaporation capacity ≥150t / h, pressure ≥9.8MPa, temperature ≥540℃), the tonnage of biomass entering the grate furnace per unit time increases, making the secondary air of the original small-capacity grate furnace unable to meet the large-capacity demand. The original small-capacity grate is small and the required primary air rate is small. Now with the development of large capacity, the grate that needs to burn biomass needs to be increased, and at the same time the primary air rate also increases, and the secondary air rate also changes accordingly, so a new secondary air structure is needed. Summary of the invention

[0003] The present invention overcomes the shortcomings of the prior art and provides a secondary air structure for a biomass water-cooled vibrating grate boiler. The secondary air structure is suitable for use with large-capacity biomass grates.

[0004] A secondary air structure for a biomass water-cooled vibrating grate boiler, the secondary air structure is arranged above the vibrating grate, and comprises a front wall secondary air duct group and a rear wall secondary air duct group arranged simultaneously in the furnace, the secondary air of the front wall secondary air duct group is sprayed to the front middle and rear of the vibrating grate, and the secondary air of the rear wall secondary air duct group is sprayed to the front and middle of the vibrating grate.

[0005] The front wall secondary air duct group comprises a front wall upper air duct and a front wall lower air duct. The secondary air of the front wall upper air duct is sprayed to the rear of the vibrating grate, and the secondary air of the front wall lower air duct is sprayed to the front middle of the vibrating grate.

[0006] The counterclockwise angle between the axis of the air duct on the front wall and the front wall surface is an acute angle.

[0007] The clockwise angle between the axis of the air duct under the front wall and the front wall surface is an acute angle.

[0008] The rear wall secondary air duct group includes a rear wall air duct, and the clockwise angle between the axis of the rear wall air duct and the rear wall surface is an acute angle.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] The secondary air structure designed in the present application arranges secondary air duct groups on the front wall and the rear wall at the same time, controls the injection angle, and matches the air volume ratio of the primary air and the secondary air. It is suitable for large-capacity biomass grates and can better supplement the air on the vibrating grate, so that the biomass fuel can be burned as much as possible on the vibrating grate, and the burnt is more complete, greatly reducing the loss of unburned carbon.

[0011] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the arrangement of the secondary air structure on the front wall and rear wall of the furnace in this application;

[0013] Figure 2 This is a schematic diagram of the air duct arrangement on the front wall;

[0014] Figure 3 This is a schematic diagram of the air duct arrangement under the front wall;

[0015] Figure 4 This is a schematic diagram of the rear wall air duct layout;

[0016] Figure 5 This is a diagram of the pipe type used for the front wall air duct in the embodiment;

[0017] Figure 6 The pipe type diagram of the rear wall air duct in the embodiment;

[0018] Figure 7 Schematic diagram of a large-capacity biomass grate furnace to which the present application applies.

[0019] The reference numerals are as follows:

[0020] 1. Biomass silo, 2. Screw feeder, 3. Chute, 4. Feed port, 5. Vibrating grate, 7. Furnace, 8. Flue 1, 9. Flue 2, A. Front wall secondary air duct group A, A1. Front wall upper air duct, A2. Front wall lower air duct, B. Rear wall secondary air duct group, B1. Rear wall air duct. DETAILED DESCRIPTION

[0021] The embodiments of the technical solution of the present application will be described in detail below in conjunction with the accompanying drawings. Unless otherwise specified, the technical terms or scientific terms used in the present application are generally understood by those skilled in the art to which the present invention belongs.

[0022] The biomass enters the screw feeder 2 through the biomass silo 1, enters the chute 3 through the positive pressure feeding system of the screw feeder, and then enters the feeding port 4 in front of the grate, where a feeding gate valve is arranged, and then enters the vibrating grate 5, and is burned on the grate 5. In order to improve the burnout of the biomass, secondary air is arranged on the water-cooled wall on the upper part of the vibrating grate 5. The generated flue gas exchanges heat to the water-cooled wall and the superheater heating surface in the furnace 7, flue 1 8 and flue 2 9 respectively, and transfers the heat to the steam for power generation.

[0023] As biomass grate furnaces develop towards large-capacity ultra-high pressure and above, combined with the primary and secondary air ratio of high-pressure biomass grate furnaces and field operation measured data. The biomass grate is larger, the primary air rate is increased, and the primary and secondary air ratio is changed from the original 35:65 to 45:55 in combination with actual conditions. Although the secondary air rate has decreased, the boiler capacity has increased, the amount of fuel has increased, and the air volume has increased accordingly. In view of this, the secondary air structure needs to be redesigned.

[0024] Figure 1 A secondary air structure suitable for a large-capacity biomass water-cooled vibrating grate boiler is demonstrated, wherein the secondary air structure is arranged above the vibrating grate 5, and comprises a front wall secondary air duct group A and a rear wall secondary air duct group B arranged simultaneously on the furnace 7, and the secondary air structure is arranged on the front wall and the rear wall of the furnace. In order to better supplement the air on the grate, the secondary air has a certain injection angle and injection stiffness. The secondary air of the front wall secondary air duct group A is injected to the front, middle and rear of the vibrating grate 5, and the secondary air of the rear wall secondary air duct group B is injected to the front and middle of the vibrating grate 5, so that the biomass fuel can be burned as much as possible on the vibrating grate 5, thereby reducing the loss of unburned carbon.

[0025] In order to ensure the spray angle, the front wall secondary air duct group A refers to Figure 2 and Figure 3 , for the secondary air duct design of large-capacity biomass water-cooled vibrating grate, the front wall is sprayed to the front middle and rear of the grate, so the secondary air duct of the front wall is designed with two groups of structures, divided into the front wall upper air duct A1 and the front wall lower air duct A2. The front wall secondary air duct group A includes the front wall upper air duct A1 and the front wall lower air duct A2. The secondary air of the front wall air duct A1 is sprayed to the rear of the vibrating grate 5, and the secondary air of the front wall lower air duct A2 is sprayed to the front middle of the vibrating grate 5.

[0026] Since the water-cooled wall (front wall) where the front wall air duct is arranged is at a clockwise angle of 47 degrees to the vertical water-cooled wall, and the air duct on the front wall is responsible for spraying to the rear of the grate, the air duct on the front wall is designed at a certain angle, and the counterclockwise angle between the axis of the air duct A1 on the front wall and the front wall 71 is an acute angle. The counterclockwise angle between the axis of the air duct A1 on the front wall and the front wall 71 ranges from 60° to 80°.

[0027] The air duct A1 on the front wall is a plurality of air ducts arranged in a staggered manner. Figure 2 As shown, the front wall surface 71 and the intersection points of the axes of the air ducts A1 on the front walls are collinear.

[0028] Exemplarily, the air ducts A1 on the front wall are three air ducts arranged in a staggered manner, and the counterclockwise angles between the axes of the air ducts and the front wall 71 are 60°, 70° and 80°.

[0029] Since the front wall downwind duct A2 sprays to the front middle part, the front wall downwind duct A2 is also designed with a certain angle, and the clockwise angle between the axis of the front wall downwind duct A2 and the front wall surface 71 is an acute angle. The clockwise angle between the axis of the front wall downwind duct A2 and the front wall surface 71 ranges from 47° to 77°.

[0030] The air duct A2 under the front wall is a plurality of air ducts arranged in a staggered manner. Figure 3 As shown, the intersection of the front wall surface 71 and the axes of the multiple front wall downwind ducts A2 are not colinear. The injection angle set in this way makes the injection rigidity reach the expected design, the biomass fuel is fully burned on the grate, and the loss of unburned carbon is greatly reduced.

[0031] For example, the front wall lower air duct A2 uses 4 staggered air ducts, and the clockwise angles between the axis and the front wall 71 are 47°, 57°, 67° and 77°. The injection angle is set in this way, so that the injection stiffness reaches the expected design, the biomass fuel is fully burned on the grate, and the unburned carbon loss is greatly reduced.

[0032] Optionally, the air duct A1 on the front wall and the air duct A2 under the front wall are both Φ108×6 air ducts. Figure 5 shown.

[0033] Since the water-cooled wall where the rear wall duct is located is 60 degrees counterclockwise from the vertical water-cooled wall, the secondary air on the rear wall of the furnace is sprayed to the front and middle of the grate. A certain angle is also designed according to the spray angle and spray direction. Figure 4 As shown, the rear wall secondary air duct group B includes a rear wall air duct B1, and the clockwise angle between the axis of the rear wall air duct B1 and the rear wall surface 72 is an acute angle.

[0034] The clockwise angle between the axis of the rear wall air duct B1 and the rear wall surface 72 is in the range of 50°-70°.

[0035] For example, the rear wall air duct B2 uses three staggered air ducts, and the clockwise angles between the axes of the air ducts and the rear wall surface 72 are 50°, 60° and 70°. The injection angles set in this way make the injection rigidity reach the expected design, the biomass fuel is fully burned on the grate, and the unburned carbon loss is greatly reduced.

[0036] Optionally, the air duct A1 on the front wall and the air duct A2 under the front wall are both Φ78×6 air ducts. Figure 6 As shown, the rear wall secondary air duct group B includes a plurality of rear wall air ducts B1, which are arranged at intervals along the rear wall water-cooled wall. The axes of the plurality of rear wall air ducts B1 are collinear with the intersection points of the rear wall surface. Figure 4 shown.

[0037] The secondary air structure based on any of the above embodiments is suitable for the secondary air demand of large-capacity biomass grate. Figure 7 The biomass grate furnace formed as shown.

[0038] The present invention has been disclosed as above with preferred implementation cases, but it is not intended to limit the present application. Any technician familiar with the profession can make slight changes or modifications to equivalent implementation cases with equivalent changes by using the above-disclosed structures and technical contents without departing from the scope of the technical solution of the present application, which still fall within the scope of the technical solution of the present application.

Claims

1. A secondary air structure for a biomass water-cooled vibrating grate boiler, the secondary air structure being arranged above the vibrating grate (5), characterized in that: It comprises a front wall secondary air duct group (A) arranged simultaneously on a furnace (7) and a rear wall secondary air duct group (B) of the furnace (7), wherein the secondary air of the front wall secondary air duct group (A) is sprayed to the front middle and rear of a vibrating grate (5), and the secondary air of the rear wall secondary air duct group (B) is sprayed to the front and middle of the vibrating grate (5).

2. According to claim 1, a secondary air structure for a biomass water-cooled vibrating grate boiler is characterized by: The front wall secondary air duct group (A) comprises a front wall upper air duct (A1) and a front wall lower air duct (A2), the secondary air from the front wall upper air duct (A1) is sprayed to the rear of the vibrating grate (5), and the secondary air from the front wall lower air duct (A2) is sprayed to the front center of the vibrating grate (5).

3. The secondary air structure for a biomass water-cooled vibrating grate boiler according to claim 2, characterized in that: The counterclockwise angle between the axis of the air duct (A1) on the front wall and the front wall surface (71) is an acute angle.

4. The secondary air structure for a biomass water-cooled vibrating grate boiler according to claim 3, characterized in that: The counterclockwise angle between the axis of the air duct (A1) on the front wall and the front wall surface (71) ranges from 60° to 80°.

5. The secondary air structure for a biomass water-cooled vibrating grate boiler according to claim 2, characterized in that: The clockwise angle between the axis of the air duct (A2) under the front wall and the front wall surface (71) is an acute angle.

6. The secondary air structure for a biomass water-cooled vibrating grate boiler according to claim 5, characterized in that: The clockwise angle between the axis of the air duct (A2) under the front wall and the front wall surface (71) ranges from 47° to 77°.

7. The secondary air structure for a biomass water-cooled vibrating grate boiler according to claim 1, characterized in that: The rear wall secondary air duct group (B) comprises a rear wall air duct (B1), and the clockwise angle between the axis of the rear wall air duct (B1) and the rear wall surface (72) is an acute angle.

8. The secondary air structure for a biomass water-cooled vibrating grate boiler according to claim 7, characterized in that: The clockwise angle between the axis of the rear wall air duct (B1) and the rear wall surface (72) ranges from 50° to 70°.

9. The secondary air structure for a biomass water-cooled vibrating grate boiler according to claim 2, characterized in that: The air ducts (A1) on the front wall are a plurality of air ducts arranged in a staggered manner, and the air ducts (A2) under the front wall are a plurality of air ducts arranged in a staggered manner.

10. The secondary air structure for a biomass water-cooled vibrating grate boiler according to claim 1, characterized in that: The rear wall secondary air duct group (B) comprises a plurality of rear wall air ducts (B1), and the axes of the plurality of rear wall air ducts (B1) are collinear with the intersection points of the rear wall surface.

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