The process
Milk powder, coffee and flavour spray dryers use filtered, heated supply air and an exhaust fan after cyclones and a bag filter. Hygienic construction, stainless steel, and a wheel that can be washed down.
The gas at the fan
Exhaust from a spray dryer carries fine product that is hygroscopic and sticks to any surface below dew point. A blade form that sheds deposit, insulation on the casing and easy access for cleaning.
Selection for this duty
| Blade form | Radial tipped, or backward inclined where the fan sits after the collector |
| Material of construction | Stainless steel wetted parts, with drains in the casing and a shaft seal |
| Drive and bearings | Direct coupled or belt driven; belt drive where the duty point may need tuning at site |
| Also specified | Access doors on the scroll and a wheel that can be cleaned in place; casing drain at the lowest point |
| Density at the fan | At about 100°C the gas density is close to 0.95 kg/m³, 79% 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. |
Circulates or supplies air at elevated temperature to a dryer, oven or kiln. Selected at the hot density with the shaft and bearing arrangement built for continuous hot running. Client-stated blade types for the Hot Air Fan in general: Backward curved and backward inclined.
Industries
Other fans in food and dairy spray dryers
Hot Air Fan in other processes
Hot Air GeneratorsBall Mill Raw GrindingCement Grinding MillsCement Plant Coal MillsGypsum Calcining PlantsSponge Iron Rotary KilnsSteel Reheating FurnacesHeat Treatment FurnacesForge ShopsAluminium Smelters and Cast HousesHot Dip Galvanising LinesGlass Melting FurnacesGlass Forming and Annealing LehrsCeramic Tunnel and Roller KilnsCeramic Body Spray DryersBrick and Refractory KilnsEffluent Treatment and Zero Liquid Discharge PlantsSolvent Recovery PlantsFertilizer Granulation PlantsFertilizer Rotary Dryers and CoolersRotary DryersFluid Bed Dryers and CoolersBelt 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.