The effect of AC applied voltage phase differences on the NO/sub x/ reduction from the combustion flue gases by superimposed surface and silent discharge plasma reactors

The effect of AC applied voltage phase differences on NO/sub x/ reduction from combustion flue gases by a superimposed surface and silent discharge plasma reactor is experimentally investigated. The experiments are conducted for applied voltages from 0 to 24 kV, flue rates from 0.5 to 2 l/min, ammonia mixture concentration from 0.7 to 1.2 stoichiometry, and applied phase differences from 0 to 180 degrees, where two 60 Hz AC power supplies are used. The results show that: (1) NO/sub x/ reduction rate increases with increasing discharge power, gas flow rate and ammonia stoichiometry for in-phase operations; (2) NO/sub x/ reduction rate for out-of-phase operations is much higher compared with in-phase operations. However, NO/sub x/ reduction rate has an optimum condition on ammonia stoichiometry, discharge power and gas flow rate; (3) energy efficiency of NO/sub x/ reduction increases with increasing ammonia mixture and gas flow rate, and decreases with increasing discharge power; and (4) energy efficiency of NO/sub x/ reduction under out-of-phase operations is much larger compared with in-phase operations.