Intermittent Removal Of Nitric Oxide From Flue Gas In Aqueous Solution Accompanying Reduction With Iron

With the increasingly stringent national emission standard of NOxin"twelveth five-yearplan" period, removaling of NOx(denitrification) has become imperative. For the big powerplant boiler, most of them have built SCR denitration unit and controlled NOxemissionseffective. But SCR methods are not suitable for small and medium boiler as its investment istoo large and too costly to run. Therfore, developing a suitable flue gas denitrificationtechnology for small and medium sized boiler has become an urgent need.This paper puts forward the nitric oxide removal process of aqueous solutions of ferrouschelates FeⅡEDTA combined with regeneration by iron reduction according to Ma Lefan’sresearch, and study its complexation and regeneration conditions respectively.Firstly, the denitration experiment is proceeded in the bubbling reactor with FeⅡEDTAsolution as absorption liquid, and investigate the main effect factors of the denitrationefficiency, such as FeⅡEDTA concentration, pH, O2content and the reaction temperature. Itshows that the high denitration efficiency by the method of FeⅡEDTA complexometricabsorption. Under the condition of the simulated flue gas flow rate is0.6L/min, NO entranceconcentration is400~50010-6, the temperature is323K, the initial pH of5.5and molalconcentration and volume of FeⅡEDTA solution is0.015mol/L and200mL separatelysolution, it gives above95%denitration efficiency.Secondly, the paper discusses separately the reduction process of iron powder, and seeksthe optimal reaction conditions with a homemade regeneration reactor, including the stirringspeed, the regeneration of iron powder concentration, pH and temperature factors. Theoptimal regeneration condition is that FeⅡEDTA volume is150mL, carrier gas flow rate is0.6L/min, the oxygen content is5%, the mixing speed is900RPM, iron powder concentrationwith0.12mm particle size is5.3g/L and the temperature of353K.Meanwhile, recomplexation reaction shows denitration efficiency of regenerated liquid alsocan reach above95%.Finally, we have a preliminary discuss about the reaction mechanism of theFeⅡEDTA reduction by Fe, which is in accordance with shrinking core model. Moreover, wefind that concentration distribution comform with kinetics equation dCdt0.2472C.