Performance
A cyclone has no moving parts and no media to replace. The gas enters tangentially, spins down the cone, and the dust is thrown to the wall and drops to the hopper while the cleaned gas leaves through the central outlet. It is not suitable for fine dust particles, which is why it is placed ahead of a bag filter on fine dust duties, taking the coarse load and the sparks before the bags.
Construction
Materials available include steel, aluminium and stainless steel. The hopper discharges through a rotary air lock valve. For higher efficiency on the same duty see the multiclone.
Where it is used
Cement & Lime
A cement line is a chain of fans. The preheater fan sets the kiln draft, the raw mill fan draws hot kiln gas through the mill to dry the meal, the cooler compartment fans blow air up through the clinker bed, the cooler vent fan exhausts the surplus, and the coal mill fan carries pulverised coal to the burner. Air slide blowers move meal and cement around the plant. Every one of these handles abrasive dust, so radial tipped and wear-protected backward curved impellers are the norm, with bag filters or multiclones on each exhaust.
Power
Thermal power stations use the full boiler fan set at the largest sizes: ID fans on the flue gas after the ESP, FD fans for secondary air, PA fans for mill air, and seal air blowers to keep pulverised coal out of the mill bearings. Coal handling plants add dust extraction fans on the crushers and transfer points, with bag filters and cyclones on the collected air.
Iron & Steel
Pig iron and steel plants need fans for the blast furnace stove, the sinter plant, the coke oven and the fume extraction over converters and electric arc furnaces. Combustion air blowers feed the stoves and reheating furnaces. Fume exhaust fans handle hot, dust-laden gas from the melt shop into bag filters. ID fans on the sinter strand and the boiler are built for abrasive dust and high temperature.
Fertilizer
Fertilizer plants handle dust from granulators, dryers and coolers, and fumes such as ammonia and fluorides from reactors. Bag filters take the dust, wet scrubbers take the gas, and the fans behind them are built in stainless steel or lined construction. High pressure blowers serve the dryer and cooler drums.
Ceramic
Tile, sanitaryware and refractory plants run spray dryers, kilns and glazing lines. Hot air fans recirculate kiln air, ID fans exhaust the kiln and spray dryer, and dust extraction fans with cyclones and bag filters clean the air from presses and glazing booths.
Driers
Rotary, fluid bed, spray and belt dryers all need a hot air fan to push heated air into the product and an exhaust fan to pull the moist, dust-laden air out through a cyclone or bag filter. The exhaust fan is sized at the hot, wet condition, and axial fans are used where the pressure is low.
Tobacco
Tobacco processing generates fine dust from cutting, drying and blending. Bag filter fans on the dust extraction system are the main duty, with cyclones as pre-collectors. Dryer exhaust and general ventilation complete the set.
Coal Handling
Coal handling plants raise dust at every crusher, screen and transfer point. Dust extraction fans draw the air into bag filters and cyclones, and the whole system is built spark resistant. Seal air blowers on the mills keep coal dust out of the bearings.
By process
The same duty, selected for the gas of each process.
Information needed to select or quote
- Gas volume and temperature. Actual flow at the inlet, normal and upset temperature, moisture.
- Dust or pollutant. Inlet loading, particle size distribution, whether it is abrasive, sticky, hygroscopic or combustible; for gases, the species and concentration.
- Required outlet. The emission limit or clean gas concentration the unit must meet.
- Site. Available space and height, material of construction preferences, and how the collected material is to be discharged.