Simultaneous Removal of Extremely High or Low Concentration NOx, SOx and Particulate Using Plasma Emission Treatment Combined Concentrating Technology

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Based on nonthermal plasma chemical hybrid process developed previously, simultaneous removal of particulates, NOx and SOx was developed for treating the low concentration (30〜200 ppm) emission from the power plant and the boiler application. This system consists of two-stage dry plasma oxidation process and wet chemical process. In addition, the indirect plasma method which NO can be oxidized to NO_2 extremely effective by injecting the activated air into the high temperature gas in the range of 300℃, which the required gas flow rate to be treated by the plasma was reduced to less than 1/5 of the primary gas flow rate. This indirect plasma technique was further expanded from the laboratory experiment to the pilot-scale NOx and SOx treatment system from the boiler emission in the range of 450〜1,470 Nm^3/hr for both city gas and heavy oil firings. The NOx removal efficiency for gas firing exceeds 90% but NOx removal efficiency for oil firing was somewhat lower due to the lack of ozone c … More oncentration with the present pulse power supply. The removal efficiency of SO_2 was in the range of 85〜90%. The quality of treated water from the scrubber was investigated and proved to be disposed. Moreover, the plasma concentration technique was developed to convert the large flow rate with low concentration gas to small flow rate with high concentration. That is, the low concentration flue gas was first adsorbed on the adsorbent materials such as molecular sieve 13X pellets or hydrophobic zeolite honeycomb for a long time and the pulsed plasma was applied to the adsorbent material to desorb the adsorbed NO within few minutes. Then, the high concentration NO with low flow rate was treated by the plasma-chemical hybrid process, which was able to reduce the size of the plasma reactor. Reaction byproducts were identified to be low. Moreover, a new technology for treating more than 2,500 ppm NOx was developed to reduce NO directly to N_2 using the nitrogen plasma in dry one-step process. The combination of NOx concentration technique and nitrogen plasma is able to achieve an extremely economical and attractive system and can be used for many industrial applications. Less