A bottom air device for preventing coking and high temperature corrosion of the tube wall of the combustion zone of a furnace

Abstract

The utility model relates to the technical field of coal -fired boiler, concretely is a bottom air device of preventing furnace combustion area pipe wall coking and high temperature corrosion, it can effectively solve the coking problem, avoid high temperature corrosion and will not burst pipe of water cooled wall pipe, it includes the furnace water cooled wall ash bucket, its characterized in that, the furnace water cooled wall ash bucket outside is provided with the secondary air duct, the left and right side water cooled wall and the lower portion front and rear water cooled wall of furnace water cooled wall ash bucket are provided with the hot air interface of intercommunication secondary air duct respectively.

Description

Technical Field

[0001] This utility model relates to the field of coal-fired boiler technology, specifically to a bottom air device for preventing coking and high-temperature corrosion of the tube walls in the combustion zone of the furnace. Background Technology

[0002] In boilers burning coals with a high tendency to coke (such as Zhundong coal), coking is easily triggered due to the low ash melting point and unfavorable ash composition of the fuel. Furthermore, the tangential arrangement of the burners at the four corners can easily lead to flame scouring or adhesion to the furnace walls. In the area near the water-cooled walls, the lower airflow velocity and poorer mixing can easily create a locally oxygen-deficient reducing atmosphere, further exacerbating the coking tendency in the combustion zone. If a flame-retardant strip is installed on the water-cooled walls in the burner area, it will weaken the heat absorption capacity of the water-cooled wall tubes, causing the wall surface temperature in this area to be significantly higher than that of the exposed water-cooled walls without the flame-retardant strip. This induces coking in the flame-retardant strip, which not only easily causes high-temperature corrosion of the water-cooled wall tubes but also significantly increases the risk of boiler tube rupture. Summary of the Invention

[0003] To address the aforementioned technical problems, this utility model provides a bottom air device to prevent coking and high-temperature corrosion of the tube walls in the combustion zone of the furnace. It can effectively solve the coking problem, avoid high-temperature corrosion of water-cooled wall tubes, and prevent tube bursting.

[0004] The technical solution is as follows: a bottom air device for preventing coking and high-temperature corrosion of the pipe wall in the combustion zone of the furnace, comprising a furnace water-cooled wall ash hopper, characterized in that a secondary air duct is provided outside the furnace water-cooled wall ash hopper, and hot air inlets connecting to the secondary air duct are respectively provided on the left and right water-cooled walls and the lower front and rear water-cooled walls of the furnace water-cooled wall ash hopper.

[0005] A further feature is that the hot air inlets at the left and right water-cooled walls are inclined along the inner sides of the front and rear water-cooled walls of the furnace water-cooled wall ash hopper. The secondary air duct is equipped with an expansion joint and is fixed by a hanger.

[0006] By adopting this utility model, secondary hot air is introduced into the water-cooled ash hopper area. The secondary air enters the combustion zone along the water-cooled wall, improving the atmosphere near the water-cooled wall and forming an "air curtain" protective layer. This enhances the airflow disturbance in the furnace, specifically protecting the high-incidence area of ​​coking, avoiding high-temperature corrosion of the water-cooled wall tubes and preventing tube bursts. Attached Figure Description

[0007] Figure 1 This is a front view of the structure of this utility model; Figure 2 Left view of the structure of this utility model: Figure 3 This is a top view of the structure of this utility model. Detailed Implementation

[0008] See Figure 1 , Figure 2 , Figure 3 As shown, a bottom air device for preventing coking and high-temperature corrosion of the pipe wall in the combustion zone of a furnace includes a furnace water-cooled wall ash hopper 1. A secondary air duct 2 is provided outside the furnace water-cooled wall ash hopper 1. A secondary air inlet 3 is provided on the secondary air duct 2. Hot air inlets 4 connecting to the secondary air duct 2 are respectively provided on the left and right water-cooled walls and the lower front and rear water-cooled walls of the furnace water-cooled wall ash hopper 1. The hot air inlets 4 at the left and right water-cooled walls are inclined along the inner side of the front and rear water-cooled walls of the furnace water-cooled wall ash hopper 1, that is, they are set against the wall.

[0009] Secondary hot air entering from the left and right water-cooled walls directly injects oxidizing air into the reducing atmosphere region near the water-cooled walls, effectively disrupting the reducing atmosphere and transforming it into an oxidizing or weakly oxidizing atmosphere. This inhibits the reduction of ferric iron in the coal ash to ferrous iron, significantly increasing the melting point of the ash particles and ensuring they are solid upon contact with the water-cooled walls, making them less prone to adhesion. Furthermore, the wall-mounted air blowing vertically upwards from the ash hopper area forms a continuous upward-flowing air curtain on the water-cooled wall surface, preventing molten or semi-molten fly ash particles from directly impacting the water-cooled wall tubes. It also lowers the temperature in the near-wall region, further promoting ash particle solidification before contact with the wall. This airflow also interacts with the main combustion airflow, enhancing airflow turbulence in the lower part of the furnace, promoting later mixing of pulverized coal and air, aiding in complete combustion, and preventing unburned pulverized coal from continuing to burn in the near-wall region, creating localized high temperatures.

[0010] An expansion joint 5 is installed on the secondary air duct 2 to absorb expansion and is fixed by a hanger 6.

Claims

1. A bottom air device for preventing coking and high-temperature corrosion of the pipe walls in the combustion zone of a furnace, comprising a furnace water-cooled wall ash hopper, characterized in that, A secondary air duct is provided outside the ash hopper of the furnace water-cooled wall. Hot air inlets connecting to the secondary air duct are provided on the left and right water-cooled walls and the lower front and rear water-cooled walls of the ash hopper of the furnace water-cooled wall.

2. The bottom air device for preventing coking and high-temperature corrosion of the combustion zone pipe walls in a furnace according to claim 1, characterized in that, The hot air inlets at the left and right water-cooled walls are inclined along the inner sides of the front and rear water-cooled walls of the furnace water-cooled wall ash hopper.

3. The bottom air device for preventing coking and high-temperature corrosion of the combustion zone pipe walls in a furnace as described in claim 1, characterized in that, The secondary air duct is equipped with an expansion joint and is fixed by a hanger.

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