Laboratory and Field Test of a Sampling Method for Characterization of Combustion Aerosols at High Temperatures

Abstract

The objective of this study was to design and experimentally examine a sampling method for high-temperature aerosols from biomass combustion, in which nucleation and condensation from fly ash forming vapors is controlled. The sampling method includes a high-temperature probe in which the hot gas is diluted and then cooled. Laboratory results from sampling a model aerosol with known concentrations of SiO 2 particles and KCl vapor showed that when using a high dilution ratio, the KCl vapor was effectively separated from the aerosol by deposition onto the probe walls. When a lower dilution ratio was used, the KCl vapor generated a distinct nucleation mode when cooled in the probe. The sampling method was also used for sampling flue gas from a circulating fluidized bed boiler fired with forest residues. The results suggest that the major fractions of Ca, K, S, and Zn were present as particles at 780• C, whereas most of the Cl and Pb were present as gases. The field results are consistent with results previously reported and indicate that the method can be used for efficient and precise characterization of high-temperature combustion aerosols containing inorganic vapors.

Characterization of particulate matter formed during wood pellet gasification in an indirect bubbling fluidized bed gasifier using aerosol measurement techniques

“…By using different dilution ratios and dilution gas temperatures, nucleation and condensation of inorganic vapors can be controlled. Either the vapor is guided to completely deposit in the probe, forced to condense on existing PM or form a distinct ultrafine mode that is clearly distinguishable from the original PM, as discussed more in detail by Strand et al [19]. Subsequently the tars can be removed prior to the actual PM measurements using e.g.…”

“…The hot gas can also be diluted, e.g. by means of a dilution probe [16][17][18][19][20][21][22]. By using different dilution ratios and dilution gas temperatures, nucleation and condensation of inorganic vapors can be controlled.…”

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

“…Their condensation constitutes the main contributor to the fine ash fraction. Strand et al [282] identified two principal routes for condensation of these vapors into particles: a homogeneous nucleation where the vapor condenses into very fine droplets and agglomerates/accumulates into a particle and a heterogeneous condensation where the vapor on the surface of an existing particle entrains in the flue gas.…”

Deactivation of SCR Catalysts by Exposure to Aerosol Particles of Potassium and Zinc Salts

“…According to Strand et al (2004), the particle characteristics of the boiler flue gas are 1.2 × 10 7 particles/cm 3 n with a geometric mean diameter of 68 nm, consisting of K, S, and Cl.…”