Many kilns, by definition, are refractory lined – using materials
which are resistant to decomposition by heat, pressure or chemical
attack. The refractory retains its strength and form at high
temperatures.
Basically, rotary kilns are rotary shells that are insulated on the
inside – which must be done with precise engineering, design and
installation of the refractory bricks or other interior lining.
Special focus must be placed on the critical relationship between
the dryer shell and its rolling components.
Hengyang Industry
Hengyang Industry provides both refractory lined Direct-Fired Kilns
and Indirect Heat Kilns – often for incineration and gasification
of petroleum sludges, biomass, or municipal solid waste. The
process material is heated in the rotary unit and in a semi-inert
gas stream. The complex organic molecules are converted to
synthesis gas. This syngas is withdrawn to a secondary combustion
system – ultimately converting waste to energy.
Feeding/discharge:
Automatic and continuous. Vibrators, screw feeders, rotary
airlocks, double flap valves, gravity chutes
Feed Characteristics:
Powders, granules, non-friable agglomerates. Low to high feed rates
<45tph
Heat Source:
Electrical, steam, gas, liquid fuel
Exposure:
Product contacts the heated surface of the drum. Special lifters
turn the product exposing the new product to the heated surface.
Residence time:
Controllable. Residence time can be altered by varying the speed of
rotation of the drum and the drum angle. Fill can be varied. Fills
are typically between 5% and 20% of the cross-sectional area of the
drum.
Extraction:
Normally induced but depends on the process requirements.
Dust Collection:
Systems can be low dust with minimal separation requirements.
If required cyclones, baghouses, scrubbers, Electrostatic
precipitators.
Control:
PLC, infrequently solid-state controllers. System controls on
discharge temperature. Can modulate energy and feed.
Benefits:
High throughput
Excellent energy utilization for electrical units
Can have zoned temperature profile
Gentle handling
Intimate product contact
High-temperature operation – can be refractory lined.
The unit can have an integral cooling section.
Limitations:
Incorrect seal design can cause leakage
Large real estate required
High temperature can cause damage to certain components
