Boiler and Kiln Draft Fan Duty
Forced draft and induced draft duty on boilers, kilns and dryers, with fly ash, temperature tiers and materials.
The duty
Forced draft is clean air; induced draft is everything else
A forced draft fan moves ambient or tempering air into the furnace: clean gas, moderate pressure, high efficiency available, and a backward curved or backward inclined wheel is usually the right machine. An induced draft fan moves the products of combustion out: hot, often damp, carrying fly ash, and frequently coated with condensable deposits. That is an exhauster duty, and it is where the design conversation actually starts.
Temperature decides the tier. Up to about 200 C a standard build works. Above that our high temperature range is built in tiers to roughly 250, 350, 500 and 650 C, with the material grade, thermal clearance and bearing isolation designed for the tier rather than retrofitted afterwards.
Fly ash is a wear specification
Radial and shrouded exhauster wheels with hard-faced tips, replaceable inlet rings and bolted casing liners. The spares list belongs in the quotation, not in a later emergency.
Data we need
Flue gas data that changes the design
Draft fan data
- Gas flow at the fan in CMH, at actual temperature
- Static pressure at the fan, and the draft margin the plant wants
- Fuel type and ash content, which set the dust load
- Flue gas composition, including sulphur and any condensation risk
- Continuous and peak temperature at the fan inlet
- Upstream arrester: cyclone, bag filter or none
- Start-up sequence, because a cold start on a hot-duty fan is a different stress
- Available shutdown window for maintenance and how long it is
Next step
Fans for this duty
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