The process
Solvent-laden air from coating, printing or pharma drying is passed through activated carbon beds that adsorb the solvent; the beds are regenerated with steam or hot inert gas and the solvent recovered. The process fan is spark resistant with a flameproof motor.
The gas at the fan
Air carrying solvent vapour from painting, printing or coating. Spark resistant construction, flameproof or increased safety motor, and the fan placed where the duct cannot accumulate vapour.
Selection for this duty
| Blade form | Backward curved or aerofoil for the best efficiency on clean gas |
| 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 |
| Density at the fan | At about 40°C the gas density is close to 1.13 kg/m³, 94% 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. |
Hoods, ducting and an exhaust fan that capture fume at source and deliver it to a scrubber, bag filter or stack. Fan material follows the fume: stainless steel, PP-FRP or rubber lined where it is corrosive. Client-stated blade types for the Fume Exhaust System in general: Backward inclined and radial tipped.
Industries
Other fans in solvent recovery plants
Fume Exhaust System in other processes
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.