Abstract: In response to increasingly stringent emission standards and the demand for normal pollutant synergistic control in municipal solid waste incineration (MSWI), a large-scale waste-to-energy plant with a capacity of 5 200 t/d was taken as an research object. And the migration, transformation, and synergistic removal mechanisms of flue gas pollutants from the boiler outlet to the stack were systematically analyzed. Based on continuous emission monitoring data, the removal characteristics of particulate matter, SO2, HCl, and NOx were quantitatively evaluated, and the coordinated optimization path of acid removal process control, waste heat cascade utilization, and fly ash source reduction was explored. The results showed that the multi-stage coupled purification system could achieve high-efficiency synergistic removal of pollutants, with removal efficiencies of above 99.9%, above 99.0%, above 99.9% and 80.0% for particulate matter, SO2, HCl, and NOx, respectively, and emission concentrations were significantly lower than local ultra-low emission limits. The deacidification strategy of “mainly based on semi-dry method, with dry method regulation and wet method as the bottom line” could effectively reduce excessive Ca(OH)2 addition, maintaining the fly ash generation rate at around 2%. Furthermore, by constructing a cascade utilization system of flue gas waste heat coupled with GGH and SGH, the steam consumption of the SCR system was reduced by approximately 82.6%, corresponding to an electricity saving of approximately 0.044 kWh/m3 of flue gas. This study demonstrated that flue gas treatment in MSWI plants should shift from single-pollutant control to a coupled approach integrating multi-pollutant synergistic removal and energy efficiency optimization. The proposed system optimization strategy provides practical guidance for ultra-low emission retrofits of large-scale MSWI facilities.

Key words: municipal solid waste incineration, flue gas purification, collaborative control, ultra-low emission, fly ash reduction