Novel electrostatic precipitator using unipolar soft X-ray charger for removing fine particles: Application to a dry de-NOx process

Abstract

The novel electrostatic precipitator (ESP), consisting of a soft X-ray charger and a collection part, was demonstrated and applied to a dry de-NOx process to evaluate its performance in by-product particle removal. NOx gas was oxidized by ozone (O-3) and neutralized by ammonia (NH3) sequentially, and finally converted to an ammonium nitrate (NH4NO3) aerosol with 100-nm peak particle diameter. The unipolar soft X-ray charger was introduced for charging the by-product particles in this dry de-NOx process. For the highest particle collection efficiency, the optimal operating conditions of the soft X-ray charger and collection part were investigated by adjusting the applied voltage of each device. The results showed that 99% of NOx was removed when the O-3/NOx ratio was increased to 2 (i.e., the maximum production conditions of the NH4NO3 by-product particles by the gas-to-particle conversion process). The highest removal efficiency of particle (similar to 90%) was observed with operating conditions of positive polarity and an applied voltage of similar to 2-3 kV in the charger chamber. The unipolar soft X-ray charger has potential for particle removal systems in industrial settings because of its compact size, ease of operation, and non-interruptive charging mechanism.