Experimental and Modeling Study on de-NOx Characteristics of Selective Non-catalytic Reduction in O2/CO2 Atmosphere

An experimental study of thermal de-NOx using NH3 as reductant in O2/CO2 atmosphere with the effect of SO2 and different additives was performed in a drop tube furnace. Results show that the optimum temperature window is 841–1184 °C, and the optimum reaction temperature is about 900 °C with a de-NOx efficiency of 95.4%. A certain amount of SO2 has an inhibiting effect on NO reduction. The effect of additives, including Na2CO3, C2H5OH and FeCl3, on NO reduction by NH3 is also explored. The addition of Na2CO3 and FeCl3 is useful to widen the temperature window and shift the reaction to lower temperature for the efficiency is increased from 30.5% to 74.0% and 67.4% respectively at 800 °C. Qualitatively, the modeling results using a detailed kinetic modeling mechanism represent well most of the process features. The effect of Na2CO3, C2H5OH and FeCl3 addition can be reproduced well by the Na2CO3, C2H5OH and Fe(CO)5 sub-mechanism respectively. The reaction mechanism analysis shows that the effects of these additives on NO reduction are achieved mainly by promoting the production of OH radicals at lower temperature.

The figure shows the experimental results of the effect of reaction temperature on NO reduction with a variation of atmospheres and the modeling results of reaction temperature in O2/CO2. It is seen that as the reactor temperature increases in O2/N2, O2/Ar as well as O2/CO2, the NO reduction efficiency rapidly increases up to a temperature of 900 °C reaching a maximum. It is 97.5% in O2/N2, 98.4% in O2/Ar and 95.4% in O2/CO2. The temperature windows are all around 850–1200 °C. The highest efficiency is obtained in O2/Ar as well as the lowest in O2/CO2. The modeling results reproduce well the characteristics of reaction temperature on NO reduction compared to the experimental results.Figure optionsDownload as PowerPoint slide