Radical Density Measurement at Low-Pressure Discharge Denitrification by Appearance Mass Spectrometry

Abstract

In discharge denitrification, radical production by electron collision with combustion gas is a key process which determines the denitrification process and its performance. In this study N, O, OH and H radical densities have been measured by appearance mass spectrometry in a low-pressure discharge field with parallel electrodes (2 cm gap) under simulated combustion gas flow. Also, electric field, electron number density and electron temperature at the radical sampling position have been measured by the Langmuir probe method. Under constant discharge pressure the radical density (cm −3 ) was about 10 11 -10 12 cm −3 , and the density increased with increasing the discharge current. Under constant discharge current, both the radical concentration [−] and electron temperature increased with decreasing pressure. The radical concentration in the cathode fall region was greater than that for the outer region. Additionally, we measured the concentration change of NO mixed in the simulated combustion gas and observed a little change of the NO concentration.

Catalytic Decomposition of H2O(D2O) on a Heated Ir Filament to Produce O and OH(OD) Radicals

“…In addition, in corona discharges, the discharge volume cannot be large. It is, of course, possible to produce OH radicals in DC discharges, but in such cases, the OH density is much less than those observed in pulsed discharges, in the order of 10 11 cm -3 [37], which is comparable to that observed in the present system. The merit in catalytic decomposition is that no ionic or metastable excited species are produced.…”