Combustion method of wall-type counter-firing boiler

Abstract

The invention discloses a firing method of a wall type opposed firing boiler. A plurality of burners and over-fire air spraying openings located above the multiple burners are arranged on a front wall and a back wall of the wall type opposed firing boiler respectively or are arranged on the front wall of the wall type opposed firing boiler only, and the multiple burners are arranged in a matrix mode, are arranged to be in M lines from bottom to top and are arranged to be in N columns from left to right, wherein the M is an integer larger than or equal to 2, and the N is an integer larger than or equal to 1. The firing method includes the steps of controlling the average excess air coefficient of a main firing area where the multiple burners are located to be smaller than 1, controlling the average excess air coefficient of a firing area between the over-fire air spraying openings and a hearth outlet of the boiler to be larger than 1 so as to achieve in-boiler air grading firing, and controlling the average excess air coefficient of the burners in the first line to be larger than the average excess air coefficient of the burners in the second line to the Mth line. By means of the firing method, the aim of in-time firing can be achieved.

Description

technical field [0001] The invention relates to the field of thermal machinery, in particular to a combustion method for a wall-type opposed combustion boiler. Background technique [0002] Wall-type opposed combustion boilers have been widely used in modern large-scale coal-fired power plants because of their uniform heat load and flue gas temperature distribution along the width of the furnace, which can effectively reduce the thermal deviation between the left and right sides of the heating surface in high-temperature areas. However, the wall-type counter-firing boilers in service in my country are basically imported from foreign advanced combustion technology and then digested and produced. There is a common problem that NOx emissions are seriously exceeding the standard. To solve this problem, air staged combustion technology and low nitrogen burner technology in the furnace are often used. [0003] figure 1 It is a schematic diagram of the principle of the boiler body...

AI Technical Summary

Problems solved by technology

[0007] In addition, on the one hand, delayed ignition will shorten the combustion time of pulverized coal particles in the furnace, increase the carbon content of fly ash and large slag, and affect boiler efficiency.

At the same time, the lower temperature level will also affect the stability of the combustion flame in the furnace

On the other hand, when the high-temperature mixed flue gas that will not be completely combusted in the furnace in the future flows through the upper part of the furnace and the heating surface of the horizontal flue, it will continue to burn and release heat, often causing insufficient cooling water on these heating surfaces, increasing the high-temperature slagging on these heating surfaces, Even the risk of overheating the tube burst

[0008] Since the excess air coefficient of the entire main combustion zone A is less than 1, the near-wall area of ​​the main combustion zone A is also in a strong reducing atmosphere, and the strong reducing atmosphere reduces the ash melting point of coal. When the temperature is low, it will often cause high temperature slagging on the wall of the main combustion zone, which also affects the effective heat transfer of the boiler.

[0009] In short, the use of furnace air staged combustion technology to reduce NOx emissions in wall-type opposed combustion boilers will cause a series of problems such as delayed coal ignition, poor combustion stability, low burnout rate, and high-temperature slagging.

Images