Control Strategy of PCDD/Fs in an Industrial Fluidized Bed Incinerator via Activated Carbon Injection

Abstract

The emissions of a full range of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) from incinerators have become a significant issue in both aspects of environmental and public health protection. Fluidized bed incinerators (FBI) have been widely used as a typical technology for industrial waste treatment in recent years, especially in the petrochemical industry in Japan, Germany, and Taiwan. In response to public concerns, the Environmental Protection Administration (EPA) in Taiwan had proposed strict limits on the emissions of PCDD/Fs for both industrial and municipal incinerators. The emission standard is 0.1 ng/Nm3, expressed as the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalent of 17 specific dioxins and furans congeners. These limits will potentially influence technology selection and design in combustion processes, energy recovery options, and air pollution control devices. Since fluidized bed incinerators with revolving type combustors have been continuously popular in Taiwan for handling industrial sludge, spent oils, and solid wastes, an interesting exercise is to compare the stack concentrations against the proposed standard of concentrations of dioxins and furans (i.e., 0.1 ng/Nm3 TCDD TEQ (toxicity equivalence) and search for a more cost effective way to improve the control strategy. Research findings in this article confirm that the formation and emissions of PCDD/Fs, prior to particulates control device, exhibit a substantial positive correlation with CO concentration in the flue gases. Without using the technique of activated carbon injection to reduce the emissions of PCDD/Fs, the revolving type FBI cannot comply with the emission standards of PCDD/Fs required in Taiwan.