The process
The dry process kiln line is a chain of fans from the cooler to the stack. The preheater fan sets the kiln draft through the cyclone stages, the raw mill fan draws the hot gas through the mill, the cooler fans blow and exhaust the clinker bed, and the coal mill fan carries pulverised fuel to the burner. Every gas stream carries abrasive dust at temperature.
The gas at the fan
Kiln gas leaving the preheater carries fine raw meal dust at high temperature. The fan runs hot and dusty for years between stops, so wear liners, a shaft cooling disc and bearings outside the gas path are standard.
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 330°C the gas density is close to 0.59 kg/m³, 49% 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 cement preheater 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.