Charged fraction and electrostatic collection of ultrafine and submicrometer particles formed during O_2-CO_2 coal combustion

摘要

The charged fraction of submicrometer and ultrafine particles generated during bench scale coal combustion and the subsequent penetration of particles through a cylindrical-wire electrostatic precipitator (ESP) in O_2-CO_2 and O_2-N_2 environments were measured. In all combustion environments, natural particle charging within the combustor was not adequate for high efficiency particle collection in the ESP; thus, corona generation was necessary for enhanced particle charging. With a positive applied potential, the corona inception voltage and voltage required to reach a given current level in the ESP in gas mixtures composed of O_2 and CO_2 were higher than those composed of O_2 and N_2, while similar voltages were needed for negative corona generation. In positive coronas, particle penetration through the ESP in O_2-CO_2 environments was 1-2 orders of magnitude higher than in O_2-N_2 environments. Little difference in particle penetration between O_2-N_2 and O_2-CO_2 was seen in negative coronas.