The process
Direct reduction of iron ore in a rotary kiln produces a hot off-gas full of fines that passes through an after-burner chamber and usually a waste heat boiler before the ESP and the ID fan. Shell air fans along the kiln inject air through ports, and shell cooling fans protect the refractory. Hard, continuous duties.
The gas at the fan
Rotary kiln off-gas after the after-burner chamber and waste heat boiler, carrying iron ore and coal fines. Among the harder duties for an ID fan: hot, heavily dust laden and continuous.
Selection for this duty
| Impeller | Steel or cast aluminium impeller; PAG is not used above its temperature limit |
| Form | Tube axial for low pressure; vane axial where the pressure or the downstream distribution calls for it; bifurcated where the motor must be out of hot or contaminated air |
| Density at the fan | At about 220°C the gas density is close to 0.72 kg/m³, 59% of standard air. Pressure developed and power drawn fall in the same ratio, so the selection is made at this density and the motor is checked at cold start. |
Blows ambient air onto the rotary kiln shell in the burning zone to protect the refractory and the shell steel. A row of axial fans along the kiln, each covering one length of shell. Client-stated blade types for the Shell Cooling Fan in general: Axial.
Industries
Other fans in sponge iron rotary kilns
Shell Cooling Fan in other processes
Information needed to select or quote
- Duty point. Volume flow and static pressure at the fan inlet, with the gas density and temperature or the conditions to derive it.
- Operating conditions. Site altitude, normal operating temperature and continuous or intermittent duty.
- Gas stream. Dust loading and particle size, corrosive species, moisture, upset temperature and any tendency of the material to deposit on the impeller.
- Mechanical. Rotation viewed from the drive end, discharge orientation and motor power.