Simultaneous removal of NOx and SO2 from coal boiler flue gases by DC corona discharge ammonia radical shower systems: pilot plant tests

Pilot scale tests were conducted for simultaneous removal of NOx and SO2 from coal boiler flue gases by corona discharge induced ammonia radical injection techniques, i.e. the corona radical shower system. Tests were conducted for the flue gas rate from 1000 to 1500 Nm3/h, the gas temperature from 62°C to 80°C, the ammonia-to-total acid gas molecule ratio from 0.88 to 1.3, applied voltage from 0 to 25 kV and NO initial concentration from 53 to 93 ppm for a fixed SO2 of 800 ppm. The results show that SO2 removal increases with increasing ammonia radical injection rate and non-monotonically depends on in-put electrical power. The NOx removal increases with increasing in-put electrical power and ammonia radical injection rate. Approximately 9 kg of SO2 were removed by 1 kWh of energy input with 99% of SO2 removal, while approximately 125 g of NOx was removed by 1 kWh of energy input with 75% of removal efficiency.