Hello. I have encountered the same calculation in various emission calculation reports used by the environmental agencies in my country. I have a sense that these calculations are wrong but I can't prove they are and also I can't prove that they are true
The legislation says "For nitrogen monoxide emissions, a transformation rate of 60 per cent to nitrogen dioxide shall be taken as a basis; this implies that the emission mass flow of nitrogen monoxide must be multiplied by factor 0.92 and used in the nomogram as the emission mass flow Q of nitrogen dioxide"
The same legislation limits NO2 emissions as "Emissions of nitrogen monoxide and nitrogen dioxide in waste gas from cement kilns shall not exceed a mass concentration of 0.50 g/m³, to be indicated as nitrogen dioxide."
In my opinion, for a stack with 100,000 m³/hr flowrate, the calculations should be as followed since we exactly know the allowed emission concentration as NO2:
Mass flow of NO2 = 100000 × 0.5 × 10^-3 = 50 kg/hr
However, most people follow the calculations below:
NO2 Concentration = 0.5 g/m³
MW(NO) / MW(NO2) × 0.5 = (30/46) x 0.5 ≈ 0.326 mg/m³ as NO
Mass flow of NO = 100000 × 0.326 × 10^-3 = 32.6 kg/hr
32.6 kg/hr NO x 0.92 = 300 kg/hr as NO2
I am not even sure if the molecular weight conversion is correct or not. I am really confused. I don't think so many people could be wrong but can't prove it.
Thank you very much