The ClearFlow™ rotor configuration is fast becoming the US industry standard for controlling fouling on air preheaters submitted to cyclic and low-load operation. Air Preheater
Traditional air preheater designs (as shown here to the right) use a shallow layer of closed channel heat transfer surface in the cold end, intended to contain the fouling zone and facilitate cleaning. While this is somewhat effective at full load operation, reduced temperatures associated with low load operation allow this fouling zone to expand into the adjacent, open channel element layers.
In our Clearflow™ rotor configuration (shown here to the right), element layers are arranged to maximize the soot-blowing energy to all layers, preventing diffusion of the cleaning media, which significantly improves the cleaning effectiveness. This normally involves changing from 3 layers to 2 layers, with the cold end layer being a deeper layer. Further improvements in cleanability are achieved through utilization of a basket support system that minimizes obstructions to the cleaning media; such as elimination of items such as element support grids. Retrofitting this configuration to an existing air preheater requires relatively minor modifications to the basket support arrangement.
The Clearflow™ design arrangement addresses many of the root causes of air preheater fouling, thereby minimizing the duty on air preheater cleaning equipment, and by eliminating aggressive cleaning practices, meaningful extensions in heat transfer surface life are achievable. This extension in life further demonstrates the benefit of controlling fouling in the Ljungström®