Hazardous waste is a potential danger for our environment and our health if not treated appropriately. Some hazardous waste examples are solvents, aerosols, pesticides, oil sludges, varnishes, or medical waste from hospitals. Their treatment by incineration offers the advantage that organic, toxic substances are decomposed, and waste volume is highly reduced. Furthermore, energy can be recovered and steel recycled.

The rotary kiln has become the most common technology to incinerate hazardous waste, thanks to its high capacity (up to120 000 t/a) and versatility; rotary kilns can treat solid, pasty and liquid wastes all together. Typical dimensions are lengths of 5–15 m and diameters of 3–5 m.

Solid wastes reach the kiln through a feed chute in the stationary front wall. Auxiliary fuels, liquid, and pasty wastes are injected through different nozzles placed next to the chute. The kiln is slightly inclined (~3 %) and rotates with 0,05–0,7 rpm, resulting in a mean residence time of 30–90 min for solid waste. While travelling slowly through the kiln, wastes transform into gases and a solid/liquid inorganic combustion ash, called “bottom ash”. Combustion gases are treated in a secondary combustion chamber and neutralized through different gas cleaning devices.

The mean temperature at the rotary kiln lining’s hot face was measured to be 900–1000 °C in the inlet and outlet zones, and 1000–1200 °C in the combustion zone, However, these temperatures fluctuate due to varying waste inputs, which cause thermal shocks. In addition, the kiln rotation induces a thermal cycling, since the temperatures at the top of the kiln differs from the temperatures at the bottom by approx 300 °C.

ROTARY KILN INCINERATORS are typically applied in the following KEY MARKETS:

• Medical and infectious waste incineration,
• Thermal desorption (soil cleaning),
• Hazardous waste incineration, including:
• Solid wastes,
• Sludge, slurries,
• Combustible liquids,
• Waste waters,
• High chlorinated hydrocarbons and PCB’s,
• Petrochemical wastes,
• Refinery wastes,
• Pharmaceutical wastes.