Why is the square arrangement adopted for direct current combustion burners used in industrial boilers?
Why is the square arrangement adopted for direct current combustion burners used in industrial boilers?
Due to the fact that the gas flow diffused by a single nozzle of a direct current burner has a smaller spread angle, a slower speed decay, and a longer range, high-temperature flue gas can only be mixed into the gas flow around it, making the coal powder around the gas flow boundary ignite first, and then gradually extend to the center of the gas flow, so that it ignites later and the flame travel time is longer, and the ignition conditions are not ideal.
When adopting a square arrangement, four streams of gas flow form a virtual circle with a diameter of 600-800mm in the furnace center. This circular combustion method can make the gas flow from adjacent burners mutually ignite, playing a role in helping the gas flow ignite. At the same time, when the gas flow enters the furnace, it produces strong rotation, and under the action of centrifugal force, it extends the gas flow to the surrounding, forming a negative pressure in the furnace center, so that the high-temperature flue gas flows downward from above to the root of the gas flow, further improving the ignition conditions of the gas flow. Due to the strong rotation of the gas flow in the furnace center, the coal powder and air are strongly mixed, accelerating the combustion, forming a high-temperature fireball in the furnace center, and because the gas flow rotates and rises, it extends the time for coal powder to burn in the furnace, improving the degree of filling of the gas flow in the furnace.