Polychlorinated dibenzo-p-dioxins and dibenzofurans: Removal from flue gas and distribution in ash/residue of a refuse-derived fuel combustor

Abstract

In early 1989, a joint Environment Canada/U.S. Environmental Protection Agency program investigated the effect of changing combustion and flue gas cleaning system variables on the performance of these systems. Using information from earlier characterization tests at the same test site (Mid-Connecticut facility in Hartford), performance data on a refuse-derived fuel combustor and its lime spray dryer absorber/fabric filter (flue gas cleaning) system were obtained under good, intermediate, and poor combustor operation and high, normal, and low sulfur dioxide (SO 2) control by the flue gas cleaning system. The independent combustion system variables included steam load, air supply rate, and its distribution. For the flue gas cleaning system, the outlet gas temperature from the spray dryer absorber served as an easily measurable surrogate for the approach to saturation temperature, while SO 2 concentration in the flue gas at the fabric filter outlet continuously represented lime stoichiometry. Test data included: acid gas, trace organic, trace metal, and particulate matter concentrations as well as material collection for the determination of ash/residue composition and production rates. In addition, process data and refuse-derived fuel feed and ash/residue generation rates were obtained. Correlations between combustion conditions and furnace emission of organic pollutants are presented. The removal of polychlorinated dibenzo-p-dioxins and dibenzofurans, other organics, and particulate matter from flue gas is reported. The transfer of organics to ash/residue is detailed, and the close relationship between particulate removal and organics removal is noted. The results of input/output analyses of the organics across the flue gas cleaning system are discussed.