Emissions and deposit properties from combustion of wood pellet with magnesium additives

• This work studies the amount of gaseous and particle emissions and deposits on heat exchanger surfaces in a boiler fired with commercially available pellets and with pellets primed with magnesium oxide and magnesium hydroxide. The combustion experiments were performed on a residential boiler of 20 kW. Substrates placed in the heat exchanger was analysed with SEM-EDX-mapping to evaluate the chemical composition of the deposits. The results show that particle emissions (PM 2.5) using the additives increased by about 50% and the mass of the deposits in the flue gas heat exchanger (excluding loose fly ash) increased by about 25% compared to the combustion of pellets without additives. The amount of additives was found to be eight times higher than the amount of the main alkali metals potassium (K) and sodium (Na) which leads to the assumption that the additives were overdosed and therefore caused the problems reported. The SEM analysis of the substrates placed in the flue gas heat exchanger indicate that the deposits of sodium (Na), potassium (K), chlorine (Cl) and sulphur (S) decrease using the additives. If this was due to the expected chemical reactions or due to the loose fly ash covering the substrates after the test, could not be determined in this study.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Energisystem (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Energy Systems (hsv//eng)

Nyckelord

softwood pellets

magnesium

additives

particle emissions

deposit formation

Miljö- och energisystem

Environmental and Energy Systems

Energy- and Environmental Engineering

SWX-Energi, Integrerade system för sol och biobränsle

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)