Burner elbow

Abstract

The utility model discloses a burner elbow which comprises a central air pipe arranged on a horizontal pipe of the burner elbow and further comprises a cooling air pipe, the cooling air pipe is arranged obliquely downwards and communicated with a vertical pipe section of the burner elbow, and the included angle between the axis of the cooling air pipe and the axis of the vertical pipe section is alpha, the cooling air pipe is located on the left side or the right side of the axis of the central air pipe. While reliable cooling air is provided, dust accumulation of the cooling air pipeline can be avoided, and maintenance of the central air pipe is facilitated.

Description

Technical Field

[0001] The utility model belongs to the technical field of burners, and in particular relates to a burner elbow. Background Art

[0002] Faced with the requirements of deep peak regulation and low-load stable combustion of thermal power units, when the boilers of coal-fired power plants are running at low load, the upper and middle burners are often in a shutdown state. The shutdown burners are radiated by the high temperature of the furnace and often suffer from severe high-temperature burning, which directly affects the safe and economical operation of the power station boiler. Providing cooling air to the shutdown burners can protect them from being burned by high temperatures when they are shut down. Ensuring the safe and reliable operation of the boiler is a difficult problem in the industry. At present, the cooling air of the burner is mostly introduced into the horizontal or vertical pulverized coal pipeline in front of the burner. The cooling air interface is set on the horizontal pulverized coal pipe. The cooling air inlet is far away from the burner, and the resistance is large, which affects the cooling effect and easily causes pulverized coal accumulation at the cooling air interface; the cooling air interface is set on the vertical pulverized coal pipe, but it is not convenient for the maintenance of the central air duct. Utility Model Content

[0003] In order to solve the above problems, the utility model provides a burner elbow, which can prevent dust accumulation in the cooling air duct while providing reliable cooling air, and facilitates the maintenance of the central air duct.

[0004] The embodiments of the present invention are implemented by the following technical solutions:

[0005] A burner elbow comprises a central air duct arranged on a horizontal pipe of the burner elbow, and also comprises a cooling air duct, which is arranged obliquely downward and connected to a vertical pipe section of the burner elbow, the angle between the axis of the cooling air duct and the axis of the vertical pipe section is α, and the cooling air duct is located on the left or right side of the axis of the central air duct.

[0006] In an embodiment of the present invention, the vertical pipe section is a tubular structure having a plane, and the cooling air duct is connected to the vertical pipe section from the plane.

[0007] In one embodiment of the present invention, the vertical pipe section is a horseshoe-shaped pipe, and the cross section of the horseshoe-shaped pipe includes an arc section and a U-shaped end, and the two ends of the arc section are respectively connected to the two ends of the U-shaped section.

[0008] In one embodiment of the utility model, a wear-resistant layer is provided on the inner wall of the connection point between the cooling air duct and the vertical pipe section.

[0009] In one embodiment of the utility model, the vertical pipe section and the horizontal pipe section of the burner elbow are transitionally connected via a shrimp elbow.

[0010] In one embodiment of the utility model, it also includes an exhaust gas pipe, which includes an air intake section and an air bleed section that are connected in sequence. The air intake section is fixed in the vertical pipe section of the burner elbow and is arranged concentrically with the vertical pipe section. The air bleed section extends obliquely upward from the vertical pipe section to the outside of the vertical pipe section.

[0011] In one embodiment of the present utility model, an exhaust gas regulating valve is provided in the exhaust gas duct's air inlet section.

[0012] In one embodiment of the utility model, the inner wall of the inlet of the air intake section shrinks from the outside of the tube to the inside of the tube to form a bell mouth.

[0013] The technical solution of the utility model has at least the following advantages and beneficial effects:

[0014] The utility model can avoid dust accumulation in the cooling air duct and facilitate maintenance of the central air duct by arranging the cooling air duct obliquely downward in the vertical pipe section of the elbow and locating it on the left or right side of the central air duct. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a schematic diagram of the burner elbow of the utility model;

[0017] Figure 2 It is a top view of the burner elbow of the utility model;

[0018] Figure 3 for Figure 2 AA section view;

[0019] Figure 4 It is a schematic cross-sectional view of the vertical pipe section of the burner elbow of the utility model.

[0020] Icons: 11-vertical pipe section, 111-arc section, 112-U-shaped end, 113-access plane, 12-horizontal pipe section, 13-back plate, 2-center air duct, 3-exhaust air duct, 31-intake section, 32-bleed air section, 4-cooling air duct. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0024] In the description of the present utility model, it should be noted that if the terms "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the utility model product is usually placed when used. It is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present utility model.

[0025] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "configure", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] Example

[0027] Please refer to Figure 1This embodiment provides a burner elbow, which includes a vertical pipe section 11 and a horizontal pipe section 12, and the vertical pipe section 11 and the horizontal pipe section 12 are transitionally connected by a shrimp elbow to reduce the local resistance of the elbow and optimize the coal powder flow field. The horizontal pipe section 12 of the burner elbow is also provided with a central air duct 2, and the central air duct 2 is fixed on the back plate 13 on the left side of the horizontal pipe section 12. When the central air duct 2 needs to be repaired, the back plate 13 can be removed to separately extract the central air duct 2 and the components thereon, which is convenient for on-site maintenance. The right section of the horizontal pipe section 12 is connected to the primary air duct, and the lower part of the vertical pipe section 11 is connected to the coal powder pipeline by a square and round section. When the burner is shut down, the cooling air valve is opened, and the cooling air enters the primary air duct through the burner elbow to cool and protect the primary air duct and the burner nozzle to avoid burnout of the burner. It should be noted that the shrimp elbow is not shown in the figure.

[0028] In this embodiment, the burner elbow is also provided with a cooling air duct 4, which is arranged obliquely downward and connected to the vertical pipe section 11 of the burner elbow. The angle between the axis of the cooling air duct 4 and the axis of the vertical pipe section 11 is α, α>45°, which can effectively avoid powder accumulation at the cooling air interface. When coal powder is attached to the cooling air interface, the attached coal powder will be washed away from the cooling air interface under the action of gravity and cooling air scouring, and the cooling air duct 4 is located on the left or right side of the axis of the central air duct 2, which is convenient for the maintenance of the central air duct 2. In the prior art, some cooling air ducts 4 are also installed in the vertical pipe section 11 of the elbow, but the cooling air duct 4 is located on the front of the central air duct 2. When the central air duct 2 needs to be removed from the elbow horizontal pipe and moved out horizontally, the cooling air duct 4 is just located on the horizontal movement path of the central air duct 2, hindering the removal of the central air duct 2. In this embodiment, the cooling air duct 4 is arranged on the left or right side of the axis of the central air duct 2, thereby avoiding the problem of the cooling air duct 4 hindering the removal of the central air duct 2.

[0029] In this embodiment, the vertical pipe section 11 of the burner elbow is a tubular structure with a plane, such as a round tube with a plane or a polygonal tube with a plane, and the plane is the access plane 113. The cooling air duct 4 is connected to the vertical pipe section 11 from the access plane 113. The vertical pipe section 11 of this embodiment is a horseshoe-shaped tube, and the cross section of the horseshoe-shaped tube includes an arc section 111 and a U-shaped end 112. The two ends of the arc section 111 are respectively connected to the two ends of the U-shaped section, and the plane of the side of the U-shaped section is the access plane 113. The vertical pipe section 11 adopts a square-like U-shaped section structure on one side, which can better connect with the horizontal pipe section 12 of the elbow, and at the same time provide a plane for the access of the cooling air duct 4, reducing the difficulty of elbow manufacturing. The other side of the vertical pipe section 11 adopts a circular arc section 111, and adopts a shrimp bend method to transitionally connect with the round tube of the horizontal pipe section 12, which can reduce the local resistance of the elbow and optimize the coal powder flow field.

[0030] In this embodiment, a wear-resistant layer is provided on the inner wall of the connection point between the cooling air duct 4 and the vertical pipe section 11. The wear-resistant layer can adopt a structure lined with silicon carbide ceramics, and the wear-resistant layer can be provided on the inner wall of the entire burner elbow to prevent wear.

[0031] In this embodiment, the cooling air duct 4 is arranged obliquely downward in the vertical pipe section 11 of the elbow and is located on the left or right side of the central air duct 2, so that dust accumulation in the cooling air duct 4 can be avoided and maintenance of the central air duct 2 is convenient.

[0032] In this embodiment, a back plate 13 with a flat plate structure is used at the transition between the vertical pipe section 11 and the horizontal pipe section 12, which can reduce the curved centrifugal force of the original curved back plate 13 of the elbow. In the prior art, a curved back plate 13 is used at the transition between the vertical pipe section 11 and the horizontal pipe section 12 of the burner elbow. Due to the centrifugal effect, when the coal powder airflow passes through the elbow, the coal powder airflow at the outlet of the elbow will have local areas of concentrated coal powder and local areas of diluted coal powder along the circumferential direction. In this embodiment, a back plate 13 with a flat plate structure is used at the transition between the vertical pipe section 11 and the horizontal pipe section 12, which can avoid the problem of uneven circumferential distribution of the coal powder airflow at the outlet end of the elbow due to the centrifugal force after the coal powder airflow passes through the elbow.

[0033] In the prior art, when a coal-fired boiler is operating under low load, the air-to-coal ratio at the outlet of the pulverizer is high and the pulverized coal concentration is low. Due to the rapid diffusion of flame heat, the flame temperature decays sharply, and it is difficult for the burner to sustain stable combustion after ignition. In addition, the structure of the coal-fired boiler is complex and the space is limited. The use of a complex pulverized coal concentration separation device will bring about problems such as large floor space and difficulty in layout. In addition, when burning high-moisture lignite, the primary air rate is usually large, and there are also problems of high air-to-coal ratio and low pulverized coal concentration. In this regard, the present embodiment installs an exhaust gas pipe 3 on the burner elbow to achieve the separation of the pulverized coal airflow before it enters the main burner, thereby increasing the pulverized coal concentration of the primary air of the main burner to improve the ignition and stable combustion capabilities of the pulverized coal burner.

[0034] Specifically, the exhaust gas pipe 3 is L-shaped, and includes an air intake section 31 and an air bleed section 32 which are connected in sequence. The air intake section 31 is fixed in the vertical pipe section 11 of the burner elbow and is arranged concentrically with the vertical pipe section 11. The inner wall of the inlet of the air intake section 31 shrinks from the outside of the pipe to the inside of the pipe to form a bell mouth, and the shrinkage angle β is 3° to 15°, so as to form a negative pressure area at the inlet of the exhaust gas pipe 3 to guide the airflow into the exhaust gas pipe 3, and the air bleed section 32 extends obliquely upward from the inside of the vertical pipe section 11 to the outside of the vertical pipe section 11, and is provided with an exhaust gas regulating valve. The exhaust gas ratio can be adjusted by adjusting the exhaust gas regulating valve. Under low-load operation of the boiler unit, before the pulverized coal airflow enters the burner elbow, the pulverized coal particles have a relatively high momentum, while the air has a lower momentum. Due to the difference in momentum between the pulverized coal particles and the air, the pulverized coal particles are concentrated in the area near the pipe wall under the centrifugal action of the cyclone arranged upstream, or the elbow separation or impact separation. Most of the concentrated pulverized coal airflow is sprayed into the furnace through the burner along the outer elbow of the exhaust gas pipe 3, and a small part of the light pulverized coal airflow in the central area of ​​the vertical pipe section 11 is separated as exhaust gas and flows into the exhaust gas pipe 3. The outlet of the exhaust gas pipe 3 is connected to the furnace. The pulverized coal airflow separated by exhaust gas has a higher pulverized coal concentration and a stronger stable combustion capability.

[0035] When the boiler is operating normally at high load and the primary air rate and pulverized coal concentration are appropriate, the exhaust gas regulating valve of the exhaust gas pipe 3 is closed, and all the pulverized coal flows into the burner through the elbow, and the burner organizes stable combustion.

[0036] When the boiler is operating normally at high load, the primary air rate and pulverized coal concentration are appropriate. The exhaust gas regulating valve in exhaust gas pipe 3 can also be set to a certain opening to further increase the pulverized coal concentration of the main burner, thereby achieving the purpose of reducing nitrogen oxide emissions.

[0037] When burning high-moisture lignite, the primary air rate is high. The exhaust gas regulating valve is opened, and part of the light coal powder airflow flows into the exhaust gas pipe 3 as exhaust gas, and most of the dense powder particles enter the main burner along the outer elbow of the exhaust gas pipe 3, reducing the primary air rate of the main burner and achieving stable and efficient combustion.

[0038] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A burner elbow, comprising a central air duct arranged on a horizontal pipe of the burner elbow, characterized in that: It also includes a cooling air duct, which is arranged obliquely downward and connected to the vertical pipe section of the burner elbow. The angle between the axis of the cooling air duct and the axis of the vertical pipe section is α, and the cooling air duct is located on the left or right side of the axis of the central air duct.

2. The burner elbow according to claim 1, characterized in that: The vertical pipe section is a tubular structure with a plane, and the cooling air duct is connected to the vertical pipe section from the plane.

3. The burner elbow according to claim 2, characterized in that: The vertical pipe section is a horseshoe-shaped pipe, the cross section of which includes an arc section and a U-shaped end, and the two ends of the arc section are respectively connected to the two ends of the U-shaped section.

4. The burner elbow according to claim 1, characterized in that: A wear-resistant layer is provided on the inner wall of the connection point between the cooling air duct and the vertical pipe section.

5. The burner elbow according to claim 1, characterized in that: The burner elbow vertical pipe section and the horizontal pipe section are transitionally connected via a shrimp elbow.

6. The burner elbow according to claim 1, characterized in that: It also includes an exhaust gas pipe, which includes an air intake section and an air bleed section that are connected in sequence. The air intake section is fixed in the vertical pipe section of the burner elbow and is arranged concentrically with the vertical pipe section. The air bleed section extends obliquely upward from the vertical pipe section to the outside of the vertical pipe section.

7. The burner elbow according to claim 6, characterized in that: An exhaust gas regulating valve is provided in the exhaust gas inlet section of the exhaust gas pipe.

8. The burner elbow according to claim 6, characterized in that: The inner wall of the inlet of the air inlet section contracts from the outside of the tube to the inside of the tube to form a bell mouth.

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