Operation of a Wire-Plate Pulsed Corona Plasma Reactor for Flue Gas Control

Abstract

Summary form only given. Pulsed corona plasma (PCP) reactors offer novel solutions to problems concerning environmental issues in power generation and in a number of industrial processes. Emerging technologies like PCP conversion of noxious compounds in flue gases (nitrogen oxides, sulfur oxides, heavy metals), decomposition of (halogenated) hydrocarbons from industrial processes, or the decomposition of tar-like substances in bio-derived gaseous fuels rely on high efficiency, high throughput plasma reactors. We report on experimental investigations of a laboratory size, wire-plate plasma reactor for pulsed corona treatment of gas flows. Results concerning experiments in ambient air without gas flow, characterising the reactor performance with and without application of a DC bias voltage, have been published previously. Operation with gas flow, at pulse repetition frequencies of between 10 pps and 1000 pps, is reported in this work. Pulse voltage amplitudes were varied between 10 and 28 kV, at pulse duration of typically 150 ns (FWHM). As a model system for benchmarking of the simulation of plasma kinetic processes in the reactor, the formation of ozone in this system is investigated experimentally as well as theoretically. The results of both experiment and numerical simulation of the plasma-chemical processes are presented and discussed. Whereas the maximum ozone concentration of over 1000 ppm was achieved for pure DC operation, the ozone production efficiency was lowest for DC operation and highest for pulsed operation. In pulsed operation without DC bias voltage, an efficiency of around 70 g/kWh has been achieved, which is more than 5 times the DC value and compares well with published results from commercial installations using atmospheric pressure DBD (dielectric barrier discharge) in pure oxygen. The experimental results were compared with results from gas-phase simulations for both DC and pulsed operation. Whereas for DC operation the average reduced electric field in the vicinity of the wires of the order of 100 Td very consistently reproduced the experimental results, the pulsed operation requires a correction of the reduced electric field strength to considerable higher values of up to 300 Td. Taking into account the field enhancement at the streamer head, this assumption is in accordance with results from earlier work