Christian Pfeiffer Machine Factory, South Africa

Hot Gas Generator for a Coal Grinding Plant in South Africa

In Danielskuil, South Africa, two new lime shaft kilns were constructed at the local lime plant IDWALA-LIME. The two kilns are fired with locally sourced bituminous coal.

To process the raw bituminous coal into fine coal dust, Christian Pfeiffer Maschinenfabrik GmbH (CPM) was commissioned to design and build a complete coal drying and grinding plant. The system prepares and refines the raw coal for use as fuel in the lime kilns.

The coal processing plant consists of a ball mill, classifier, filter, raw coal storage silo, coal dust storage silo, inertization system, and hot gas generator (HGE) for drying the coal.

Hot gas generator for coal drying

CPM commissioned Carbotechnik with the design, manufacture, and commissioning of the hot gas generator. The system was designed to provide reliable and efficient hot gas generation for the coal drying process.

The scope of supply included:

• Hot gas generator with coal dust dosing system
• Output of 1.35 MW
• Hot gas temperature of 200–290°C
• Downstream mixing chamber
• Ignition gas line
• Control cabinets and control software
• All necessary field devices

CPM carried out the mechanical installation on site.

Special requirements for the hot gas generator

The project presented several technical challenges. One key feature was the vertical arrangement of the hot gas generator. In addition, the end customer classified the area around the burner head as ATEX Zone 22, requiring the system design to meet the corresponding explosion protection requirements.

Another important requirement was to minimize the number of sparks entering the ball mill together with the hot gas. This was particularly important for the safe operation of the coal grinding and drying plant.

To improve coal combustion and achieve a stable flame, Carbotechnik designed the mixing chamber with an extended length. This design provides additional space for the combustion process and helps ensure that the hot gas reaches the ball mill with as few sparks as possible.

With its customized design, the hot gas generator provides a reliable heat source for drying the bituminous coal and supports the safe and efficient operation of the complete coal grinding plant.