Process and apparatus for calcining materials with very diverse grain sizes, more in particular limestone

摘要

In order to enlarge the application range of rotary kilns with shaft preheaters and shaft coolers with regard to the grain size that can be used and, in particular, to expand it to finer grain size lower limits, a method for burning materials of very different grain sizes in the grain size range from 5 to 50 mm, in particular limestone gravel, is used in a rotary kiln with a shaft preheater and shaft cooler proposed to periodically and alternately give up the original grain size of the fuel feed material, broken down into two or more grain fractions of a narrow bandwidth, to the furnace system, whereby the bulk layers of the fuel material through which the process gases flow in the shaft preheater and shaft cooler are changed in their thickness by automatic control so that their thickness Flow resistance always remains the same. This method can be used in a shaft preheater, consisting of burn shafts arranged polygonally around the gas inlet shaft with displacement tappets on the bottom, a truncated pyramidal, polygonal displacement body in the middle above the gas inlet shaft and a feed shaft located concentrically above it, with the feed shaft at the lower end of the feed shaft in the inlet sector A layer height adjustment slide is arranged for each individual firing shaft, which are located below the exhaust gas space via a lever mechanism. the adjustment device can be moved up and down.