Dilution Air Blower for Crematoria

The process

Gas fired crematoria need an ID fan to hold the chamber under draft through the after-burner and any scrubber, with dilution air to protect the fan and stack. Quiet running matters at these sites.

The gas at the fan

Flue gas after the quench and scrubber is wet, acidic and still carries fine dust. The fan is in stainless steel or lined construction, with a shaft seal and drains, sized at the saturated density.

Selection for this duty

Blade form	Radial tipped, or backward inclined where the fan sits after the collector
Material of construction	Stainless steel on all wetted parts, grade to suit the gas analysis
Drive and bearings	Direct coupled or belt driven with a shaft cooling disc and bearings outside the casing
Also specified	Casing drain at the lowest point
Density at the fan	At about 200°C the gas density is close to 0.75 kg/m³, 62% 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.

Injects ambient air into a hot flue gas stream to bring it down to a temperature the downstream bag filter or fan can accept. Client-stated blade types for the Dilution Air Blower in general: Backward curved.

Industries

Other fans in crematoria

Dilution 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.