Innovative Cleaning of Air Preheater Coils With Pressurized Liquid Nitrogen (LN₂)

Cleaning of air heaters in power plants or recovery boilers has been traditionally done with high pressure water, chemicals or steam. These techniques, while effective on moderate air-side fouling of heat exchange surfaces, are usually ineffective on more tenacious deposits that can develop in coal-fired plants with buildup of fly ash, dust and oil. If these deposits are not cleaned periodically, the heat transfer in the heaters is reduced, which in turn reduces boiler efficiency and increases a unit’s heat rate. Severe fouling on air preheaters and air heaters can even reduce a unit’s Mw output. This paper discusses the recent introduction of a highly effective method of cleaning air heaters utilizing pressurized liquid nitrogen (LN₂). A success story at PPL Generation’s Brunner Island plant illustrates the effectiveness of this new technology.