OCR Text |
Show CONCLUSIONS There are two areas in this MWC where CDD/CDF is formed. The first area is in the combustor. The CDD/CDF concentrations measured in the mixing chamber are most likely products of incomplete combustion carried through the system with the large entrained particulate matter. The wet quench removes a significant amount of PM and reduces the CDD/CDF concentration at the ESP inlet to low levels. The second area of CDD/CDF formation occurs in the ESP. This formation is strongly dependent on operating temperature. In tests without sorbent injection, a reduction in nominal ESP inlet temperature from 571 to 397°F (299 to 203°C) decreased stack emission of CDD/CDF by a factor of 10. In tests with furnace injection of limestone, a reduction in nominal ESP inlet temperature from 391 to 306°F (199 to 152°C) decreased stack emission of CDD/CDF by approximately a factor of 2. Duct injection of hydrated lime at the lowest ESP temperature provided the lowest CDD/CDF outlet concentrations. Outlet CDD/CDF concentrations increased 70% when injecting limestone into the furnace as compared with no sorbent injection at an ESP operating temperature of 400°F (204°C). This increase was probably the result of a decrease in ESP performance (higher PM emission rates) during furnace sorbent injection tests. REFERENCES 1. Schindler, P.J. "Municipal Waste Combustion Assessment: Combustion Control at Existing Facilities," EPA-600/8-89-058 (NTIS PB90-154931), August 1989. 2. Scheil, G., et aI., "Municipal Waste Combustion Multipollutant Study, Emission Test Report, Maine Energy Recovery Company Refuse-Derived-Fuel Facility, Biddeford, Maine, Volume I: Summary of Results," EPA-600/8-89-064a (NTIS PB90-22883.(), July 1989. 3. Kilgroe, J.D., T.G. Brna, A. Finkelstein, and R. Klicius, "Control of PCDDIPCDF Emissions from Refuse-Derived Fuel Combustors," accepted for publication in Chemosphere, Proceedings of International Symposium on Chlorinated Dioxins and Related Compounds (Dioxin '89). 15 |