Four‑Channel Burner Structure and Function of Each Air Duct (from Inside to Outside)

1. Central Air Duct

- The air volume is the smallest, and the air pressure is 6～8 kPa

- Functions: ① Cool and protect the heat‑resistant steel at the burner head to prevent high‑temperature deformation and burnout; ② Form a central recirculation zone to stabilize and straighten the flame and avoid flame sweeping the coating; ③ Reserve a passage for the ignition oil gun / igniter for kiln heating and ignition

- Adjustment: Opening the central air wider enlarges the recirculation zone, widens the flame root and shortens the flame; excessively low central air may lead to backfire and burnout of the burner head

2. Pulverized Coal Duct (Coal Carrier Air)

- Carries pulverized coal together with conveying air; the conveying wind speed is 20～30 m/s. The inner wall of the duct is lined with wear‑resistant lining to resist erosion by pulverized coal

- Functions: Pneumatically convey pulverized coal, ensure uniform ejection of pulverized coal and prevent coal deposition and pipeline blockage. The solid‑gas ratio of coal carrier air is a key parameter; a higher solid‑gas ratio facilitates low‑nitrogen dense‑phase combustion

- Note: Coal carrier air is supplied separately by a coal Roots blower. Its air volume generally does not undergo wide‑range adjustment to guarantee stable pulverized coal conveying

3. Swirl Air (Inner Air)

- Equipped with swirl vanes; air pressure is 24～26 kPa, and the air is ejected in a rotating pattern

- Core function: Disperse pulverized coal and promote lateral diffusion. Increasing swirl air shortens, thickens and diverges the flame. A larger swirl angle delivers stronger dispersion capacity. A larger swirl angle is required for burning anthracite to facilitate ignition

4. Axial Air (Outer Air)

- High‑speed direct jet with wind speed up to 150～200 m/s and air pressure of 23～25 kPa

- Core function: Constrain the flame, provide flame rigidity, entrain high‑temperature flue gas inside the kiln to the flame root to ensure rapid ignition of pulverized coal. Increasing axial air lengthens and narrows the flame

5. Flame Stabilizing Hood (Head Fitting)

A cylindrical component at the front end of the burner. It constricts the flame root, eliminates local peak temperature, reduces thermal NOₓ formation, protects the kiln mouth guard plate and kiln mouth refractory, and prevents flaring deformation of the kiln mouth shellFlame adjustment mantra:

Swirl governs flame thickness, shortness and spread;

Axial flow governs flame rigidity and length;

Central air governs flame stabilization and alignment.