Simultaneous Removal of SiF4 and NOx Using Corona Discharge
Morvová M., Gašparík R., Hensel K., Švehla B.
5th International Symposium on High Pressure Low Temperature Plasma Chemistry HAKONE V, Mílovy (Czech Republic), September 2-4, 92-96 (1996)
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Abstract: The combustion exhaust containing NOx, flourosilicate SiF4, heavy-metals and othertoxic compounds were treated with small scale equipment (10 Nm3/hour) on by-pass of theglass oven. The equipment consists of two corona discharge blocks (each contain 12 coaxialcorona discharge tubes), with gas flow rate 4.5 m/s. The gas flow is directed firstly downwardsand then upwards (in U shape). The ultrasonic aerosolator was used for spray of Ca(OH)2water solution for neutralisation on the inlet of discharge system. The size of droplets was 0.5-10 μm and applied amount between 0,5-2 l/hour of liquid. The discharge parameters wereU=7,8 kV, discharge current I=13,5 mA, power consumption 7,86 Wh/Nm3.The removal efficiencies were 71% for NOx, 74% for SiF4 converted to HF, 68% for allCl containing compounds converted to HCl, 99,2% for Pb, 95,5% for As. The negative polarityof discharge appeared more effective. The qualitative analyses of products were performedusing IR analysis (gaseous products) and isokinetic sampling (solid particles) by authorisedmeasuring group. Analysis of solid and liquid products from the system was realisedadditionally using IR spectrometry. The solid fluorosilicates CaSiF6, silane SiH4, CaF2, NO2Fand NOF were found as products from IR absorption spectra.
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