Effect of ambient air temperature on the performance of regenerative air preheater of pulverised coal fired boilers

The air preheater (APH) is the last heat trap in flue gas path of boiler. Efficient performance of APH is possible with efficient pre-combustion coal drying and effective combustion in the furnace. The characteristic of ambient air temperature (AAT) has a significant role on the efficiency of heat transfer in APH. The change in AAT in turn changes heat capacity of air that depends on relative humidity (RH) and air density. An increase in AAT will reduce the waste heat recovery opportunity, if sufficient reserve capacity of heat exchange is not available in APH. Besides, change in AAT will have an impact on the power consumption of the fans and leakage through different seals. In this paper, the effect of these factors due to change in AAT is evaluated to assess the performance of regenerative APH with reference to a field study of 135 MWe subcritical steam power plant.