The process
Paddy dryers are fired with husk in a furnace or hot air generator, with the hot air fan supplying the dryer and cyclones taking husk dust from the milling section. Husk ash and husk dust are both abrasive.
The gas at the fan
Rice husk ash is high in silica and among the most abrasive fly ashes a boiler fan handles. Blade wear is the limiting factor; wear liners, hard facing and a blade form that resists erosion set the design.
Selection for this duty
| Blade form | Radial tipped with wear liners, or straight radial where the dust is coarse |
| Material of construction | Mild steel with replaceable wear liners on the blades and the scroll at the cut-off |
| Drive and bearings | Direct coupled or belt driven with a shaft cooling disc and bearings outside the casing |
| Also specified | Hard facing or liners on the blade pressure face |
| Density at the fan | At about 180°C the gas density is close to 0.78 kg/m³, 65% 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. |
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. Client-stated blade types for the Ventilation Fan in general: Backward inclined and forward curved.
Industries
Other fans in rice mills and paddy dryers
Ventilation Fan in other processes
Bagasse Fired BoilersRice Husk Fired BoilersAFBC BoilersCFBC BoilersPulverised Coal Fired BoilersOil and Gas Fired BoilersBiomass Fired BoilersCement Packing and DispatchElectric Arc Furnace SteelmakingInduction Furnace Melt ShopsHeat Treatment FurnacesForge ShopsAluminium Smelters and Cast HousesIron and Non-ferrous FoundriesGlass Forming and Annealing LehrsBrick and Refractory KilnsChemical Reactor and Tank VentsMVR EvaporatorsEffluent Treatment and Zero Liquid Discharge PlantsPharmaceutical Clean RoomsSolvent Recovery PlantsGas Compressor StationsBelt and Tray DryersTea Withering Troughs
Services on this fan
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.