Abstract: A comprehensive technical analysis of SNCR and SCR process was carried out and corresponding economic model was set to analyze operation cost of different DeNOx processes for a 500 t/d plant. The results showed that SNCR was much more cost effective than SCR. The cost of reductant generally accounted for about 70% of the total cost of SNCR， and the cost of heat loss caused by reductant solution evaporation in the furnace could not be ignored. The economic difference of reductants should be reasonably analyzed with help of the isocost line. The operation cost of SCR was four to five times that of SNCR， the flue gas heating cost counted over half of the total cost while the direct cost of reducing agent was only 6%. The electrical consumption of urea pyrolysis process was over twice than that of ammonia process， thus ammonia solution was more cost effective than urea.

Key words: waste incineration, DeNOx, ammonia solution, urea