Combustion Emissions from d-RDF (Densified-Refuse Derived Fuel) Pellets: Bench-Scale Studies

Abstract

A series of smoldering combustion tests were performed on samples of d-RDF (densifiedrefuse derived fuel) and clean wastepaper pellets over the temperature range of 400°-800°C in l00°C increments. These tests attempted to simulate the inadequate combustion conditions often found in small industrial or residential airtight heating stoves A high value of 729 pg/g of 2,3,7,8 TCDD (dioxin) was produced in the replicate 700°C (- l,250°F) tests on the d-RDF pellets. At 800°C no dioxin was detected in the ash samples. The d-RDF ash also contained a variety of heavy metals in significant amounts. The clean wastepaper pellets, by contrast, produced a clean ash over the same smoldering (low-oxygen) combustion temperatures. The ash from these pellets contained low levels of both the primary dioxin and the heavy metals. While it appears that the wastepaper pellets are suitable for a convenience fuel for small industrial or residential heating stoves, the d-RDF pellets do not seem suitable for this purpose. The d-RDF pellets seem to be best utilized in larger furnace industrial and institutional applications where proper combustion and stoichiometric controls can be maintained. This would ensure that the dioxins are destroyed by the high temperature combustion conditions and the ash and flue dust materials can be properly managed.