Comparison of porous and nonporous alumina bed materials for PAHs formation during plastic waste fluidized-bed incineration

Abstract

In order to understand adsorption effect of porous materials on PAHs generation during waste fluidized-bed incineration, comparison of porous and nonporous alumina bed materials for PAHs formation was experimentally investigated in a plastic waste fluidized-bed incinerator. Meanwhile, the distributions and contents of gaseous PAHs, particulate associated PAHs, PAHs precursors (monocyclic aromatic hydrocarbons and light hydrocarbon) in the dense region, freeboard region and outlet of the incinerator were also measured. The results indicated that ethylene (C2H4), ethyne (C2H2), propene (C3H6), benzene (C6H6), and styrene (C8H8) were the main precursors for PAHs formation. The 3-ring and 4-ring PAHs were dominant, and the particulate associated PAHs was the main components in flue gas. Meanwhile, the gaseous PAHs and particulate associated PAHs were respectively reduced by 49.20% and 39.41% when the non-porous alumina was replaced by the porous alumina bed materials. Based on the PAHs formation routes, the suppression mechanism for PAHs formation was proposed that the porous alumina adsorbed more PAHs precursors in the dense region due to its higher adsorption capacity, simulateously reduced the evolution rate of the PAHs precursors and prolonged the residence time of PAHs precursors in the freeboard region of the incinerator.