Adaptive Control for NO_x Removal in Non‐Thermal Plasma Processing

Abstract

This paper presents results on NOx removal using a dielectric packed‐bed plasma reactor where the reactor energy is varied in real time to optimise NOx removal. An automated system has been developed using computer‐control with an industry standard software package, a multifunction DAQ card, on‐line fast FTIR spectroscopy and adaptive PID algorithms. The automatic control system has demonstrated real‐time control of plasma conditions which minimises the input energy for NO conversion for a range of input NO concentrations. The dependence of [NO]out on deposited energy density has been used to create a multidimensional response surface for NO destruction. This, in turn, has been used to create a fully validated process control model of the entire reactor‐FTIR‐adaptive PID system.

The Effect of Temperature on the Plasma-Catalytic Destruction of Propane and Propene: A Comparison with Thermal Catalysis

“…The voltage and current supplied to the plasma reactor are monitored in real time by two digital sampling modules (Pico ADC-200, 10 MHz bandwidth, 8-bit, 20 MS s -1 ) which allow the control computer to continuously monitor the electrical power supplied to the plasma by integrating the current and voltage waveforms [8]. The plasma power was kept constant (within 1%) throughout each set of experiments: 1 W for propane removal and 0.5 W for propene removal.…”

Fundamental Properties and Applications of Dielectric Barrier Discharges in Plasma‐Catalytic Processes at Atmospheric Pressure

“…Some of the most prominent applications of atmospheric pressure DBDs include the plasma-catalytic purification of exhaust gas streams by removing CO [15], NO x [16], SO 2 [17] and VOCs [18]. Especially the total oxidation of VOCs to CO 2 and H 2 O is one of the major challenges in environmental protection and can be used to obtain fundamental insight into the plasma-chemical mechanisms.…”

“…For example, the reactivity of the plasma may prevent catalyst deactivation or reduce catalyst poisoning. DBDs are widely used for ozone production [13,14], exhaust gas purification removing CO [15], NO x [16], SO 2 [17] or volatile organic compounds (VOCs) [18]. Depending on the given plasma-catalyst configuration, the longlived or/and the short-lived species generated in the plasma can contribute to chemical conversion.…”

Gas-Phase Chemistry in Inductively Coupled Plasmas for NO Removal from Mixed Gas Systems

“…One possible approach to improving the performance of materials used in catalytic converters employs plasmas to either modify the catalyst surface or enhance removal or excitation of the pollutants themselves. Previous studies concentrated on the removal of nitrogen oxides using dielectric barrier and corona discharges, along with microwave and hollow cathode plasmas. − Small amounts (typically hundreds to thousands of parts per million) of NO were added to these systems to mimic the amount of NO found in vehicle exhaust. Other plasma-catalytic studies focused on different variables such as catalyst preparation, type of catalyst used, and type of exhaust (e.g., diesel exhaust instead of gasoline). − Generally, these studies focused on the overall processes occurring as a function of applied plasma power, and not on complete removal of NO.…”