Towards improving airheater design to minimise corrosion: modelling of a single tube

Boiler air heater tube corrosion costs the industry several million dollars a year in repairs, reduced boiler steam output and reduced boiler efficiency. There have been many cases where the reduced boiler steam output caused by leaking air heater tubes has reduced factory crushing rates and electricity export. Air heater corrosion has previously been addressed through multiple options, including more expensive corrosion resistant materials, as well as using computational fluid dynamics to improve the gas and air flow distributions with turning vanes and ductwork redesign. Evolving hardware and software modelling capabilities provide more options to critically study the gas velocity and temperature profiles, and, hence, potentially achieve improved understanding of the wall interaction, deposition and corrosion processes. This paper presents the computational fluid modelling details and results for a single tube at the air inlet.