Abstract
Plasma chemical hybrid process has been investigated for the control of NOx flue gas emissions. Previous results have shown that nonthermal plasma is able to oxidize NO to NO2 but cannot reduce NO2 to N2 effectively. As for the nonthermal plasma processes, part of the NO2 is converted to form N2O, HNO3 and NO3-. Several hydrocarbon additives, catalysts, and water film combined with the nonthermal plasma process have been investigated to enhance NOx reduction, but NOx reduction has been limited to the 70% range and byproduct formation still remains to be unsolved. As an alternative technology, the plasma chemical hybrid process was developed: plasma reactor to convert NO to NO2, and the chemical reduction process to convert NO2 to N2 with minimum byproducts. The barrier dielectric packed-bed reactor followed by the chemical reactor was able to achieve nearly 100% NOx decomposition with an extremely low power level (14 W/cfm, 30 J/L, or 40 eV/molecule) and minimum N2O formation. The operating costs for the nonthermal plasma reactor and the chemical reactor are $1,290/ton of NO and $440/ton of NO2, respectively. The total operating cost becomes $1,730/ton, which is at least 20 times more economical compared to the nonthermal plasma alone and the other conventional NOx control technologies.