Combustion Air Blower for Blast Furnace Hot Blast Stoves

The process

Hot blast stoves heat the blast air for the furnace, burning cleaned blast furnace gas with combustion air from dedicated fans. The duty is clean, steady and critical, with dampers switching stoves between heating and blowing.

The gas at the fan

Clean air to the hot blast stoves at steady pressure. A combustion air duty where reliability over long runs is the requirement.

Selection for this duty

Blade form	Backward curved or aerofoil for the best efficiency on clean gas
Material of construction	Mild steel
Drive and bearings	Direct coupled or belt driven; belt drive where the duty point may need tuning at site
Density at the fan	At about 40°C the gas density is close to 1.13 kg/m³, 94% 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 blast furnace hot blast stoves

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.