The turbulence consideration in predicting efficiency of electrostatic precipitation for ultrafine aerosols from small-scale biomass combustion

Abstract

This work investigates the efficiency of electrostatic precipitation for ultrafine particulate matter (PM) emissions from small-scale heating units with solid fuel combustion. The removal efficiency for particles smaller than 50 nm was of research interest. The effect of electric parameters and operation conditions of precipitation was studied. Some appropriate models considering the impact of turbulent diffusion have been used to predict the efficiency of a specific electrostatic precipitator (ESP). The electric field in studied ESP was intensified from 1.8 × 105 V/m to 2.8 × 105 V/m, and Nt-product (the product of number concentration of ions and charging time) was varied from 1.1 × 1014 ions × s/m3 to 7.1 × 1014 ions × s/m3. The prediction correctness is considered by comparing to experimental measurements carried out at the ESP used to control emissions from a 160-kW boiler. The changes in number particle concentration were measured with two technics simultaneously. It was found that an increase in field strength in mentioned range affects the ESP removal efficiency strongly and evenly. In contrast, the effect of growing Nt-product has a limit on precipitating efficiency of 4 × 1014 ions × s/m3. The results of the present work could be helpful in the practical engineering of electrostatic precipitation.