Oxidation behavior of particulate matter sampled from the combustion zone of a domestic pellet-fired boiler

This article describes an experimental investigation of the oxidation behavior of particulate matter (PM) sampled with the aid of a rapid dilution probe from a number of measurement positions located in the near the burner region of a domestic wood pellet-fired boiler. Morphology and chemical composition of the collected PM samples were examined in a scanning electron microscope equipped with an energy dispersive X-ray spectroscopy detector. To evaluate the oxidative reactivities of the PM samples, experiments were performed in a quartz reactor with an inlet oxygen concentration of 500 ppm in a nitrogen flow, a temperature of 900 °C, and a flow rate of 1000 mL/min (STP). Results obtained from the oxidation tests indicated that the PM samples collected from locations near the visible flame boundary were significantly less reactive towards O2 than those sampled from locations along the burner axis. This fact may be due to the higher temperatures occurring near the visible flame boundary, resulting in PM samples with a higher degree of material organization and a lower availability of active sites.