What the fans do here
Sugar mills fire bagasse, a wet, fibrous fuel that produces a heavy fly ash load. The boiler fan set (ID, FD, SA and PA) is sized for bagasse's high moisture and the seasonal run, and the ID fan impeller is built for erosion. Wet scrubbers or multiclones clean the flue gas before the stack, and ventilation fans handle the heat in the mill house and pan floor.
Applications in this industry
| Application | What it does | Type usually selected |
|---|---|---|
| ID Fan | Sits at the outlet of a boiler, kiln or furnace and draws the flue gas through the plant to the stack. It handles hot, dust-laden gas at large volume, so it is sized at the hot condition and checked at cold start. | Backward curved, backward inclined and radial tipped |
| FD Fan | Supplies combustion air to a boiler or furnace, pushing ambient air through the air heater and into the windbox against the furnace draft. Clean air, so the blade is chosen for efficiency. | Backward curved and backward inclined |
| SA Fan | Supplies the secondary combustion air that completes burning above the grate or around the burner. On bagasse and biomass boilers it also carries the over-fire air that controls the fuel bed. | Backward curved and backward inclined |
| PA Fan | Supplies the air that dries the pulverised fuel in the mill and carries it to the burners. Runs at higher pressure than the FD fan because it must overcome the mill and the fuel piping. | Backward curved and radial tipped |
| Ventilation Fan | Moves air through a plant or building for fresh air supply, heat removal and fume dilution where the system is ducted. Low pressure, long hours, so efficiency and noise set the selection. | Backward inclined and forward curved |
| HVAC | Supply, return and exhaust fans for heating, ventilation and air conditioning of plant and office space. Low pressure, so efficiency and noise govern. | Axial, backward inclined and forward curved |
Processes in this industry
Equipment supplied
Centrifugal Fans
0.3 to 120 m³/s, 25 to 3120 mmWC single stage. Six blade configurations, three drive arrangements.
Wet Scrubber
Static, spray tower, packed bed, venturi and cyclonic spray types. Efficiency to 99.9% down to 5 micron.
Multiclone
Bank of small cyclones in one housing. To 90% down to 20 micron, with hopper and rotary air lock.
Axial Fans
0.3 to 70 m³/s, 3 to 75 mmWC. Direct drive, belt drive and bifurcated. Fixed or variable pitch impellers.
Information needed to select or quote
- Duty point. Volume flow and static pressure at the fan inlet, with the gas density and temperature or the conditions to derive it.
- Operating conditions. Site altitude, normal operating temperature and continuous or intermittent duty.
- Gas stream. Dust loading and particle size, corrosive species, moisture, upset temperature and any tendency of the material to deposit on the impeller.
- Mechanical. Rotation viewed from the drive end, discharge orientation and motor power.