PM2.5 and SO3 collaborative removal in electrostatic precipitator

Coal-burning pollution caused harmfully to human and environment. However, the efficiency of electrostatic precipitator (ESP) for PM2.5 is low. Reducing the ESP inlet temperature is widely concerned. This technology could simultaneously control of PM2.5 and SO3. In this study, a lab-scale low temperature ESP performance was designed under controlled conditions, the operating effects were evaluated under different temperature and SO3 concentration, SO3 and particles coagulation mechanism was discussed. Experimental results show that the operating temperature was important for ESP, The ESP outlet particle size showed a increasing trend that the median diameter d50 increased to 0.08μm from 0.05μm, and the d90 increased to 0.23μm from 0.09μm with the inlet temperature reduced from 150°C to 90°C. Particle removal efficiency increased when ESP inlet temperature reduced, especially particles with diameters of around 0.1–1μm increased obviously. SO3 removal efficiency improved from about 20% to above 80%, when the ESP inlet temperature drops below the acid dew point. Furthermore, SO3 binary nucleation mechanism was discussed, the analysis results of the adsorption mechanism indicated that SO3 condensation on the fly ash was mainly controlled by internal diffusion. 1 - coal-fired boiler; 2 - stirer; 3 - buffer vessel; 4 - heat tube; 5 - evaporation chamber; 6 - booster fan; 7 - metering pump; 8 - water tank; 9 - heat exchanger; 10 - ESP; 11 - desulfurization tower; 12 - metering pump. [Display omitted] •The PM2.5 removal efficiency improved and collaborative removal SO3 when ESP inlet temperature reduced.•The collection efficiency of 0.1–1μm particles was improved with temperature reduction.•SO3 and water molecules binary nucleation•SO3 condensation on the fly ash mechanism was mainly controlled by internal diffusion.