Migration and emission characteristics of ammonia/ammonium through flue gas cleaning devices in coal-fired power plants of China

To investigate the up-to-date migration and emission characteristics of NH3/NH4+ in coal-fired power plants after experienced ultra-low emission retrofitting, typical air pollution control devices including flue gas denitrification, dust collectors, combined wet flue gas desulfurization (WFGD) and wet precipitators are involved through conducting field measurements. Results show that most of excessive injected and/or un-reacted ammonia from flue gas denitrification system, whether SCR or SNCR, is converted into particle-bound NH4+ (>91%), and the rest of less 10% is carried by flue gas in the form of gaseous NH3, with the concentration value of 0.15-0.54 mg/m3 at the denitrification outlet. When passing through dust collectors, particle-bound NH4+ concentration decreases substantially along with the removal of particle matter. In WFGD, the dissolution and volatilization effects affect the gaseous ammonia concentration, which decrease when using limestone slurry and 20% solution of ammonia as desulfurizati...