Experimental Studies On The Removal Of NO_x By Pulsed Corona Combined With Absorption

Removal of NO_x was experimentally investigated with a wire-in-plate pulsed corona reactor combined with absorption. A layer of Ca（OH）₂ coated on cotton sheet as an absorbent was installed in the reactor and paralleled with corona wires. When at room temperature, inlet NO concentration 1 000 mg/m³, gas flow 3 000 mL/min, pulse frequency 50 Hz, peak voltage 30 kV, the removal of NO_x by the reactor with in situ absorption increased from 25.6% to 63.2%, compared with the reactor without in situ absorpotion. Experimental result shows that the non-thermal plasma technique combined with in situ absorption can improve the removal of NO_x effectively. It was indicated that in situ absorption of the NO₂ by Ca（OH）₂ was responsible for the promotion of NO removal. It was also found that the removal of NO_x increased with the increase of the pulse peak voltage, gas residence time and water vapor, but decreased with the increase of initial concentration. When O₂ concentration is lower than 5%, the existence of O₂ in the gas stream was beneficial for NO_x removal. When oxygen concentration increased from 0 to 5%, the removal of NO_x increased about 20% . But when the oxygen concentration is over 10%, it has a negative effect on NO_x removal. The initial concentration has an important influence on removal. It was found the concentration is higher, the removal is lower. The removal of NO_x was also experimentally investigated when there was SO₂ in simulated waste gas. It was found when the concentration of SO₂ is lower than 1 500 ppm, the concentration of SO₂ showed little effect on the removal of NO_x. But when the concentration of SO₂ is up to 2 000 ppm, the influence became obvious, and the removal discreased about 10%.Finally, in order to evaluate the feasibility of this system to industrial application, an enlargement experiment was performed to remove NO_x. It was tested that the total removal of NO_x was approximate to 50%. However, the operation parameters for the high voltage equipment and reactor need to be further optimized for industrial application.