Preheaters and calciners

Preheaters and calciners

The Zemdes cyclone preheaters and calciners have a modular design and allow a consistent process by combining the different modules. Zemdes cyclone preheaters can be adapted to new conditions by simply exchanging or adding modules.

Zemdes cyclone preheaters could have one or more strings. The one-stringed execution is used up to a capacity of 5.500 tpd. For larger capacities, usually two-stringed cyclone preheaters are used. Depending on drying requirements of raw material, four, five or six stage cyclone preheaters can be used. The 1st stage (top stage) of each preheater is a WEZ.D module. The WEZ.D module is a double cyclone, designed as de-dusting cyclone.


  • Undisturbed inlet flow.
  • Long immersion depth of the dip tube.
  • Diameter ratio of cyclone and dip tube is of 2: 1.
  • 270-¦ inlet spiral with an inclined bottom area.
  • A cyclone cone with 70-¦ wall inclination.

The Zemdes calciners are stream-duct reactors. Depending on the size of the plant, one or two calciners are used. All Zemdes calciner can be equipped with a Low-NOx module and/or a combustion chamber. The Low-NOx Module operates on the principle of staged combustion. The low-NOx module operating on the principle of staged combustion.

The flow tube reactor offers a high level of operational safety and combines a simple design with high flexibility allowing changes in the process parameters. The design for deflection at the top of the calciner provides disintegration of any possible remaining streak and leads to complete mixing of raw meal, gas and fuel. This is the precondition for optimum combustion and heat transfer


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