The process
Milling and pneumatic conveying of grain and flour raise combustible dust. Dust extraction to bag filters with spark resistant fans, and high pressure blowers for conveying lines.
The gas at the fan
Fibrous or stringy material that wraps a shrouded wheel. An open or straight radial impeller, spark resistant where the fibre is combustible, placed before or after the collector as the material allows.
Selection for this duty
| Blade form | Radial tipped, or backward inclined where the fan sits after the collector |
| Material of construction | Mild steel |
| Drive and bearings | Direct coupled or belt driven; belt drive where the duty point may need tuning at site |
| Also specified | Spark resistant construction with non-ferrous rubbing parts, shaft seal, earthing and a flameproof or increased safety motor; access doors on the scroll and a wheel that can be cleaned in place |
| Density at the fan | At about 35°C the gas density is close to 1.15 kg/m³, 95% 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. |
Pulls the process gas through the filter bags and discharges the cleaned gas to the stack. Works on the clean side, so the blade can be chosen for efficiency, with the filter pressure drop added to the duty. Client-stated blade types for the Bag Filter Fan in general: Backward curved and radial tipped.
Industries
Other fans in flour and grain mills
Bag Filter Fan in other processes
Bagasse Fired BoilersRice Husk Fired BoilersAFBC BoilersCFBC BoilersPulverised Coal Fired BoilersWaste Heat Recovery BoilersBiomass Fired BoilersCement Preheater KilnsVertical Roller Raw MillsBall Mill Raw GrindingCement Grinding MillsClinker Grate CoolersCement Plant Coal MillsCement Packing and DispatchRotary Lime KilnsVertical Shaft Lime KilnsGypsum Calcining PlantsSponge Iron Rotary KilnsSinter PlantsCoke Oven BatteriesElectric Arc Furnace SteelmakingInduction Furnace Melt ShopsLadle Furnaces and Secondary MetallurgyFerro Alloy Submerged Arc Furnaces
Services on this fan
Fan and System Performance TestingFan Energy AuditRetrofit of Low Efficiency FansDynamic Balancing and Vibration AnalysisInstallation, Commissioning and After-sales Support
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.