• • Outlet dust concentration reduced from 25.32 mg/m³ to 7.95 mg/m³ after retrofit, a 68.6% reduction, at a specific dust collection area of 118 m²·s/m³ and 987 MW load, demonstrating significant efficiency improvement for high-ash coal and sludge co-combustion.
• • Sludge co-combustion increased flue gas moisture content and dust viscosity, leading to severe anode plate deposition and back corona in the first electric field, which caused high-voltage power supply flashover and low secondary voltage/current.
• • Pneumatic rapping eliminated low-acceleration zones on anode plates, achieving effective dust cleaning and restoring secondary voltage and current, thereby enhancing ESP performance under challenging fuel conditions.
• • The retrofit was validated on a 1000 MW commercial unit, proving scalability and providing a reference for similar ESP retrofits in coal-fired units undergoing biomass co-combustion or low-load operation.