Capture efficiency of coal/biomass co-combustion ash in an electrostatic field

Abstract Ash samples from corn stalk and coal co-fired at 0%, 5%, 10%, 15%, 20%, and 100% biomass were collected by a 4-stage wire-pipe type electrostatic precipitator (ESP), and the ratio of 14C/12C in ash samples from the 0%, 20%, and 100% co-firing scenarios were measured by an accelerator mass spectrometer. The differential capture efficiency in electrostatic fields for coal ash, coal/biomass co-combustion ash (co-ash), and pure biomass ash was studied separately based on the ratio 14C/12C. Other factors that may influence capture efficiency were analyzed, including microscopic morphology, resistivity, dust density, and particle size distribution. The results indicate that co-ash may be efficiently captured by ESP, while pure biomass ash could not. Co-ash capture was mainly concentrated in the first two electrostatic fields in the lab-scale ESP, and the overall capture efficiency exceeded 90%. Biomass addition decreased the resistivity of co-ash, and enhanced its surface adsorption capacity to form agglomerates, facilitating the capture of co-ash. The capture efficiency of coal ash in co-ash was higher than that of pure coal ash in the first electrostatic field of the ESP. Co-firing biomass can aid the removal of both coal ash and biomass ash when using an ESP.