Towards ideal NOx control technology using a plasma-chemical hybrid process

The plasma-chemical hybrid process developed was extremely effective and ec onomical in comparison with the conventional selective catalytic reduction (SCR) system and other technologies for NOinfinity removal from flue gas em issions. A series of experiments was performed to quantify all the reaction by-products such as N2O, CO, HNO2, HNO3, and NO3- and to evaluate NOinfini ty removal efficiency. The optimum plasma reactor and its operating charact eristics were investigated with regard to reaction by-products and NOinfini ty removal efficiency using the ordinary ferroelectric packed-bed plasma re actor and the barrier-type packed-bed plasma reactor. The oxidation from NO to NO2 without decreasing NOinfinity concentration (i.e., minimum reaction by-products) and with least power consumption is the key for the optimum r eactor operating condition. The produced NO2 was totally converted to N-2 a nd Na2SO4 with Na2SO3 scrubbing. The barrier-type packed-bed plasma reactor having 1.5-mm-diameter electrode and 3-mm-diameter BaTiO3 pellets showed t he superior NO oxidation without producing the by-products over the convent ional packed-bed reactor. The barrier-type packed-bed plasma reactor follow ed by the chemical reactor showed extremely low operating costs (less than 1/6 of the SCR process) and achieved nearly 100% NOinfinity removal with le ss than 6 ppm of N2O and 5 ppm of CO.