Removal Characteristics of SO 3 in the Low-Low Temperature Electrostatic Precipitator

As SO3 endangered the industrial equipment and environment in the coal-fired power plants, it was necessary to give full play to the SO3 removal effect in a low-low-temperature electrostatic precipitator (LLT-ESP). The relationship between SO3 and fly ash particles was investigated during the cooling process. In addition, the SO3 removal performance in the LLT-ESP was further analyzed. The migration and deposition of SO3 into fly ash particles were promoted with the decrease in the gas temperature and the fly ash particle size, as well as the increase in the SO3 concentration. As the temperature of the gas decreased below the acid dew point (ADP), the H2SO4 vapor tended to migrate into fly ash particles with smaller sizes. The SO3 mass concentration increased significantly in fly ash particles whose sizes ranged from 0.03 to 0.26 mu m. When the operating voltage turned up, the SO3 removal efficiency was increased from 43.2% to 60.1%. The increase in the inlet fly ash concentration promoted the SO3 removal, and the removal efficiency increased by nearly 20%. When the gas temperature was below the ADP, it had little influence on the SO3 removal efficiency.