Seal Air Blower for Coal Handling Plants

The process

Crushers, screens, conveyor transfer points and bunkers raise coal dust that is extracted into bag filters. Spark resistant fans on the clean side, with dust suppression and extraction designed together.

The gas at the fan

Extraction air from coal crushing and handling. Combustible dust, so spark resistant construction throughout, with the fan after the collector.

Selection for this duty

Blade form	Radial tipped with wear liners, or straight radial where the dust is coarse
Material of construction	Mild steel with replaceable wear liners on the blades and the scroll at the cut-off
Drive and bearings	Direct coupled or belt driven; belt drive where the duty point may need tuning at site
Also specified	Spark resistant construction with non-ferrous rubbing parts, shaft seal, earthing and a flameproof or increased safety motor; hard facing or liners on the blade pressure face
Density at the fan	At about 35°C the gas density is close to 1.15 kg/m³, 95% 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.

Supplies clean air at a pressure above the mill or fan casing pressure to the shaft seals and bearing housings, so pulverised coal cannot enter. Client-stated blade types for the Seal Air Blower in general: Backward curved and radial.

Industries

Other fans in coal handling plants

Seal Air Blower in other processes

Information needed to select or quote

1. Duty point. Volume flow and static pressure at the fan inlet, with the gas density and temperature or the conditions to derive it.
2. Operating conditions. Site altitude, normal operating temperature and continuous or intermittent duty.
3. Gas stream. Dust loading and particle size, corrosive species, moisture, upset temperature and any tendency of the material to deposit on the impeller.
4. Mechanical. Rotation viewed from the drive end, discharge orientation and motor power.