Two new lime shaft furnaces are being constructed in the “IDWALA-LIME” lime plant in Danielskuil, South Africa. Both of these furnaces are being operated with domestic hard coal. Christian Pfeiffer Maschinenfabrik GmbH (CPM) was commissioned for the construction of a drying and grinding plant to process/upgrade raw hard coal into coal dust. The processing plant consist of a ball mill, separator, filter, a silo for raw coal storage and a silo for intermediate storage of the coal dust that is produced, an intertisation system and a hot gas generator needed for drying. CPM commissioned Carbotechnik for planning, fabrication and putting the hot gas generator into operation. The scope of performance encompasses a hot gas generator including a coal dust dosing machine designed for an output of 1.35 MW at a hot gas temperature of 200 – 290°C with a downstream mixing chamber and ignition gas section, the control cabinet and software as well as all required field devices. Installation is being carried out by CPM.

Special features of this project include the vertical arrangement of the hot gas generator, the ATEX zone 22 defined by the end customer in the area of the burner head and the fact that the generated hot gas has to be fed into the ball mill as free of sparks as possible. In order to accomplish this, Carbotechnik carried out the mixing chamber longer than usual for better burnout of the coal.

Summarised scope of delivery:

• Hot gas generator, output 1.35 MW
• Downstream mixing chamber
• Ignition gas section
• Dosing machine DN 1100
• Control cabinets and software