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In our previous studies, a novel NOx aftertreatment system using adsorption and reduction by nonthermal plasma desorption is proposed. In the present study, application of the system to a real stationary diesel engine generator is investigated. The NOx is first removed by adsorption, then the adsorbent is regenerated by thermal desorption using waste heat of the exhaust gas. In the regeneration process, hot exhaust gas passes through the heat exchanger tubes surrounded by the adsorbent pellets. The desorbed NOx is subsequently reduced to N2 by nitrogen nonthermal plasma. This system reduces 245 ∼ 270 ppm NOx emitted by the generator to around 50% for 8 hours.

Plasma chemical hybrid process has been investigated for the control of NOx flue gas emissions. Previous results have shown that nonthermal plasma is able to oxidize NO to NO2 but cannot reduce NO2 to N2 effectively. As for the nonthermal plasma processes, part of the NO2 is converted to form N2O, HNO3 and NO3-. Several hydrocarbon additives, catalysts, and water film combined with the nonthermal plasma process have been investigated to enhance NOx reduction, but NOx reduction has been limited to the 70% range and byproduct formation still remains to be unsolved. As an alternative technology, the plasma chemical hybrid process was developed: plasma reactor to convert NO to NO2, and the chemical reduction process to convert NO2 to N2 with minimum byproducts. The barrier dielectric packed-bed reactor followed by the chemical reactor was able to achieve nearly 100% NOx decomposition with an extremely low power level (14 W/cfm, 30 J/L, or 40 eV/molecule) and minimum N2O formation.

A regeneration of DPF with collected PM was investigated using the low temperature atmospheric pressure nonthermal plasma. The method is to use the NO2 and radicals induced by the plasma reactor to burn carbon soots deposited on DPF. First, the performances on the conversion of NO to NO2 of the three types of DPF plasma reactors were evaluated on various conditions. Next, a regeneration experiment was carried out using a barrier type pulsed corona plasma reactor. As a result, the regeneration of DPF using the plasma was confirmed when the gas temperature was 250°C.

A direct incineration or regeneration of DPF with collected PM was investigated using atmospheric pressure nonthermal plasma which was induced inside DPF. The method is to use the NO2 and radicals induced by the plasma to burn carbon soots deposited on DPF. Conversion of NO to NO2 was evaluated using three types of DPF honeycomb plasma reactors. Then, the regeneration experiment was carried out using a DPF honeycomb plasma reactor. As a result, it was confirmed that the pressure drop decreased when the plasma was turned on and the regeneration of DPF was confirmed at the low temperature of 200°C.