Abstract: In order to solve the excessive discharges of soluble salts，aerosols and other dusts that are common in the
ammonia desulfurization process，a new ammonia desulfurization ultra-low emission technology was developed. Adopting
the concept of crystallization in the tower and oxidation outside the tower，the technology takes specific designs on the
concentration area，absorption area，water scrubbing area and dust/mist removal area of the absorption tower respectively.
Two-stage water scrubbers with different mass concentrations， are combined with high-efficiency demisters and
precipitators，and two-stage mist eliminators. The oxidation tank outside the tower adopting three-layer distribution plate
technology can fully oxidize the slurry，and its overall oxidation rate is over 99%. Two-stage water scrubbing tank can
maximize the washing effect by controlling the mass concentration and taking stage-by-stage water replenishment，which
ensures the water balance of the system. This technology is applied in the ammonia desulfurization ultra-low emission
reconstruction in Fulaerji Thermal Power Plant of Huadian Environmental Protection Engineering & Technology Company
Limited.It can meet the requirements of the national ultra-low emission standards and pass the operation test.

Key words: ammonia desulfurization, ultra-low emission, crystallization in the tower, oxidation outside the tower, water
scrubbing layers of different mass concentrations, high-efficiency demister and precipitator, mist eliminator