Rotary kiln

The rotary kiln is the heart of the ROTARY KILN INCINERATOR, being the zone of primary combustion.

Options and features:

  • The rotary kiln can be constructed to the co-current or counter-current concept. In the co-current concept, the waste and combustion air move in parallel over the axis of the kiln. Flue gas discharge from the kiln is at the same end of the kiln as ash discharge. In the counter-current concept, the waste and combustion air move in the opposite direction over the axis of the kiln. Flue gas discharge is located at the feeding point of the waste, ambient combustion air supply is located at the ash discharge side of the kiln.
  • Dutch Incinerators has experience in the construction and operation of both types of rotary kiln concepts.
  • Each concept, co-current or counter-current rotary kilns, have their specific benefits and drawbacks.
  • The major advantage of counter-current kilns being the fact that the ash temperature as discharged by the kiln is lower. This creates less issues with slagging and is therefore more reliable and less complex in day to day operations. No need for a water bath for (molten) slag cooling and discharge, no risk of clogging near the kiln outlet, less mechanical issues and maintenance on the kiln outlet section. Metal recovery from the ashes is also possible as the ashes are produced in a counter-current kiln as fine grains and dust.
  • The major advantage of co-current kilns being the fact that the thermal load to the kiln feeding system is lower as flue gas temperature at the feeding side of the kiln is lower.
  • From a thermal point of view, co-current kilns are more suitable for the treatment of higher calorific wastes, as waste combustion is more gradual due to the temperature gradient over the kiln. Counter-current kilns are more suitable for the combustion of low or variable calorific wastes, as the hot flue gas helps to initiate ignition of the waste at the feeding point of the kiln and helps to evaporate water as supplied via the waste.
  • Based on long term experience, considering all the above from a practical point of view, it can be concluded that counter-current kilns are more reliable and more simple in day to day operations, under the condition that the feed system is properly designed, the latter being the case for the specific Dutch Incinerator designs.

Rotary kiln for medical waste incineration- top view