Emissions of heavy metals during fixed-bed combustion of six biomass fuels

• Few studies examine heavy metal emissions during the small-scale combustion of various solid biofuels. This issue may become more important, as one can expect new regulations governing such emissions from biomass combustion similar to those governing waste incineration. This paper investigates the emissions of particulate-associated heavy metals (i.e., Sb, As, Cd, Co, Cr, Cu, Pb, Mn, Ni, Tl, V, Hg, and Zn) during the fixed-bed combustion of six solid biofuels (i.e., stemwood from birch and pine/spruce, bark from birch and pine, salix, and oat grains) and of peat and bituminous coal for comparison. The results indicate that the flue gas concentration (normalized to 11% O2) of the sum of all measured metals (Zn excluded) during the biomass combustion tests ranged from 57 μg Nm-3 for birch stemwood to 198 μg Nm-3 for birch bark. The concentration of Zn in the flue gas was generally considerably higher than those of the other metals, ranging from 646 μg Nm-3 for spruce/pine stemwood to 7948 μg Nm-3 for birch bark. Compared with coal and peat, the biomass fuels produced higher Zn emissions, but lower or similar emissions of the sum of the other metals. The volatile behavior and concentration of the metal in the flue gases as a function of the heavy metal in the fuel are also presented for selected heavy metals.

Subject headings

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

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

TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik -- Bioenergi (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology -- Bioenergy (hsv//eng)

Keyword

Biomass

Bituminous coal

Coal combustion

Flue gases

Fuels

Lead

Metals

Peat

Waste incineration

Zinc

Energiteknik

Energiteknik

Publication and Content Type

ref (subject category)

art (subject category)