Investigation of safe operating conditions for reducing acid corrosion and ABS deposition in rotary air preheater using computational fluid dynamics

A rotary air preheater is an important energy recovery device that can reduce energy wastage to a great extent. The major issue associated with this device is the blockage inside the rotary matrix mainly due to chemical deposition such as; sulphuric acid and ammonium bisulphate (ABS). Moreover, these compounds cause substantial damage to air preheater element in terms of corrosion. The current research has been carried out to explore the optimum parametric conditions such as; inlet air and hot gas temperature, hot gas and air mass flow rate and rotational speed of rotary matrix to minimize the acid corrosion and ABS deposition. The dew point temperature of sulphuric acid and ammonium bisulphate (ABS) formation temperature were evaluated using correlations. From the simulation, it is observed that with increase in air/hot flue gas temperature, the acid corrosion area and ABS formation region decreases. When the mass flow rate of air and hot flue gas increases equally, the acid corrosion and ABS formation region increases along the cold airflow direction. With a lower mass flow rate, the ABS deposition and acid corrosion area becomes more uniform near the cold end only. Near the hot end, it seems to be corrosion-free.