Wet And Dry Process Cement Rotary Kiln in Cement Plant , Cement Kiln 55kw

Wet And Dry Process Cement Rotary Kiln in Cement Plant , Cement Kiln 55kw

Cement Rotary Kiln Process Wet and Dry Cement Rotary Kiln

With the arrival of rotary kilns, cement manufacturing processes became sharply defined according to the form in which the raw materials are fed to the kiln. Raw materials were either ground with addition of water, to form a slurry containing typically 30-45% water, or they were ground dry, to form a powder or "raw meal".

In the Wet Process, the kiln system is fed with liquid slurry, the water then being evaporated in the kiln.

In the Semi-Wet Process, raw material is prepared as a slurry, but a substantial proportion (50-80%) of the water is mechanically removed, usually by filtration, and the resulting "filter cake" is fed to the kiln system.

In the Dry Process, the kiln system is fed with dry raw meal powder.

In the Semi-Dry Process, a limited amount of water (10-15%) is added to dry raw meal so that it can be nodulised, and the damp nodules are fed to the kiln system.

Wet process cement rotary kilns Wet and Dry Cement Rotary Kiln

The original rotary cement kilns were called 'wet process' kilns. In their basic form they were relatively simple compared with modern developments. The raw meal was supplied at ambient temperature in the form of a slurry.

A wet process kiln may be up to 200m long and 6m in diameter. It has to be long because a lot of water has to be evaporated and the process of heat transfer is not very efficient.

The slurry may contain about 40% water. This takes a lot of energy to evaporate and various developments of the wet process were aimed at reducing the water content of the raw meal. An example of this is the 'filter press' (imagine a musical accordion 10-20 metres long and several metres across) - such adaptions were described as 'semi-wet' processes.

The wet process has survived for over a century because many raw materials are suited to blending as a slurry. Also, for many years, it was technically difficult to get dry powders to blend adequately.
Dry process cement rotary kilns Wet and Dry Cement Rotary Kiln

In a modern works, the blended raw material enters the kiln via the pre-heater tower. Here, hot gases from the kiln, and probably the cooled clinker at the far end of the kiln, are used to heat the raw meal. As a result, the raw meal is already hot before it enters the kiln.

The dry process is much more thermally efficient than the wet process.

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