Combustion Air Blower for Brick and Refractory Kilns

The process

Tunnel kilns for bricks and refractories need an exhaust fan on the preheat end, cooling air fans on the exit end that feed hot air to the dryer, and combustion air for the burners.

The gas at the fan

Kiln exhaust with light dust and fluorine or sulphur compounds from the body and glaze. Hot, mildly corrosive; stainless steel or coated construction on the wetted parts.

Selection for this duty

Blade form	Backward inclined or backward curved; the residual dust does not justify a radial wheel
Material of construction	Stainless steel on all wetted parts, grade to suit the gas analysis
Drive and bearings	Direct coupled, shaft cooling disc, bearings in a pedestal outside the gas stream, allowance for thermal growth
Density at the fan	At about 250°C the gas density is close to 0.67 kg/m³, 56% 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.

Feeds a burner with air at the pressure the burner register needs. Sized for the burner turndown range, and often fitted with an inlet silencer. Client-stated blade types for the Combustion Air Blower in general: Backward curved and radial tipped.

Industries

Other fans in brick and refractory kilns

Combustion 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.