NO<tex>$_x$</tex>Treatment Using Low-Energy Secondary Emission Electron Gun

Abstract

A compact and highly efficient broad electron-beam source that is capable of reducing a wide range of gaseous pollutants that are very much demanding for environmental applications. We are developing an ion-induced secondary-emission electron gun (SEEG) using wire ion-plasma source for environmental applications such as NO/sub x/ treatment. The SEEG offers uniform and large cross section electron beams suitable for the efficient reduction of gaseous pollutants. We present the first report about the application of SEEG on NO/sub x/ treatment. The performance of SEEG on NO/sub x/ treatment is quantitatively related to removal ratio and removal efficiency of 250 ppm of NO in N/sub 2/. The electron-beam irradiation was carried out in a gas treatment chamber (13 L), where the sample flue gas was flown in ambient pressure and temperature at a controlled volumetric flow rate of 2 to 14 standard liters per minute. The NO removal characteristics have been studied under various conditions such as increased gun voltage, gas flow rate, and varied pulsed-electron-beam parameters (current density and pulse length). A reasonable NO removal ratio of 20% was achieved in 60 s (repetition rate = 10 pps, current density = 28 mA/cm/sup 2/, and pulse length = 10 /spl mu/s) at the accelerating gun voltage of 100 kV. The NO removal efficiency expressed in terms of specific energy cost for NO removal is 63.15 eV/molecule. It was observed that temporal and spatial characteristics of pulsed electron beam impose a substantial effect on the NO removal and the processing efficiency. We are trying to increase the processing efficiency by reducing treatment-chamber dimensions and applying a number of well-optimized parameters.