Abstract
Dew point related fouling of regenerative rotary air heaters contributes to efficiency reduction of coal-fired boilers. This fouling commonly causes high pressure differences over the air heater steel matrix, along with elevated leakage rates, resulting in increased loading of draught group fans. These increases also conduce to excessive erosion rates, introducing premature failure of element packs and draught group components. The research problem aimed to develop, and validate, a modelling tool to predict the onset of dew point related fouling for regenerative rotary air heaters (VBA RAH model). A modelling tool equip system engineers with the knowledge to enhance operating conditions and maintenance strategies, to prevent the onset of dew point related fouling. The results yielded that the cold end of the air heater packs experience sulphuric acid dew point related fouling for at 670MW(90% MCR), at 544MW(80% MCR) and at 468MW(68% MCR) of the exposure time to the flue gas stream. Different operating and design change configurations were simulated to find potential solutions to minimize dew point related fouling and improving boiler efficiency. The tool provides a platform for identifying methods to reduce maintenance costs and production losses, which will contribute to improved and sustainable operating of coal fired power generation plants.
Highlights
The following results were obtained: 99% MCR: For 1% - 5% conversion of SO2 to SO3, 90% - 100% of the simulated metal temperatures at the cold end layer were exposed to sulphuric acid dew point conditions (25 seconds of the total 27 seconds of flue gas exposure)
The VBA RAH model was successfully developed to predict the onset of dew point related fouling and provides a platform to equip system engineers with the knowledge to enhance air heater performance
The research showed that the VBA RAH model can help improve life expectancy of air heater element packs and draught group components such as ducting, dampers and supple joints
Summary
A regenerative air heater comprises a steel matrix of stacked element plates. An induced draught fan extracts hot flue gas from the furnace which passes through the steel matrix, transferring heat from the flue gas to the element plates. A forced draught fan blows cold air through the hot element plates, which heat the combustion air to improve the boiler performance. A common problem for regenerative air heaters is dew-point related cold end fouling, which leads to insufficient heat transfer
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
