Study on the removal of escaping ammonia and fly ash from biomass combustion flue gas by micro-vortex method

Biomass power plants encounter challenges such as fly ash and ammonia leakage during power generation. To address this, a micro-vortex module was installed between the air preheater and wet desulfurization system in this study. Flue gas samples were collected from four ultra-low-emission biomass combustion units at various stages: after the denitration, air preheater, dust collector, and wet desulfurization stages. The analysis methods included fixed-source gas sampling, indigo phenol blue spectrophotometry, and ion chromatography. The study examined ammonia migration, transformation in the downstream flue gas treatment, and the micro-swirl method's impact on dust removal. The results showed that ammonia released at the denitration outlet was primarily gaseous and unevenly distributed, and it locally exceeded 2.5 mg/m3. This gaseous ammonia transformed into solid ammonia in the air preheater and dust collector, accounting for 46.5 %–65 % of the total ammonia emissions at the dust collector outlet. Following desulfurization and micro-vortex module treatment, the solid ammonia content were reduced by 30.53 %, and the fly ash concentration decreased by 94.3 %. Optimal performance was achieved at a gas flow velocity of 2.0 m/s and humidities of 60 % and 90 %, with an ammonia removal efficiency of 17.02 %.