The process
Solid fuel thermic fluid heaters supply process heat in textile, chemical and food plants. The combustion side mirrors a small boiler: an FD fan under the grate or bed and an ID fan after the dust collector, both sized for the fuel in use.
The gas at the fan
Fluidised bed combustion carries bed material fines and fly ash in the flue gas. The dust is abrasive and the loading ahead of the collector is high, so the ID fan is placed after the dust collector wherever the layout allows.
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 160°C the gas density is close to 0.81 kg/m³, 68% 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. |
Feeds a burner with air at the pressure the burner register needs. Sized for the burner turndown range, and often fitted with an inlet silencer. Client-stated blade types for the Combustion Air Blower in general: Backward curved and radial tipped.
Industries
Other fans in thermic fluid heaters
Combustion Air Blower in other processes
Bagasse Fired BoilersRice Husk Fired BoilersAFBC BoilersCFBC BoilersPulverised Coal Fired BoilersOil and Gas Fired BoilersBiomass Fired BoilersHot Air GeneratorsRotary Lime KilnsVertical Shaft Lime KilnsSponge Iron Rotary KilnsBlast Furnace Hot Blast StovesSinter PlantsCoke Oven BatteriesSteel Reheating FurnacesHeat Treatment FurnacesForge ShopsFerro Alloy Submerged Arc FurnacesAluminium Smelters and Cast HousesIron and Non-ferrous FoundriesHot Dip Galvanising LinesGlass Melting FurnacesCeramic Tunnel and Roller KilnsCeramic Body Spray Dryers
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.