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This study focuses on element behaviour during combustion in the Orhaneli thermal power plant (a 210 MW
unit, Bursa-Turkey). A total of 51 samples, feed coals (FCs), fly ashes (FAs) and bottom ashes (BAs), which
were systematically collected over an eight-week period, have been analysed for major, minor and trace elements
(Al, Ca, Fe, K, Mg, Na, S, As, B, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Ga, Ge, Hf, Hg, Li, Mn, Mo, Nb, Ni, P,
Pb, Rb, Sb, Sc, Se, Sn, Sr, Ta, Th, Ti, Tl, U, V, W, Y, Zn, Zr and REEs). This study shows that FCs on an airdried
basis have high moisture (av. 9%), high volatile matter (av. 33%), very high ash yield (av. 53%), relatively
high sulfur content (av. 2.14%) and low gross calorific value (av. 1775 kcal/kg). Proximate analyses of combustion
residues imply that BAs have higher contents of unburned carbonaceous matter than FAs. Mean values of
trace element concentrations in FCs fall within the ranges of most world coals, except for Cr, Cs, Ni and U
which occur in concentrations slightly higher than those determined for most of world coals. Some elements
such as S, Hg, As, B, Bi, Cd, Cs, Ge, K, Pb, Rb, Sb, Se, Sn, Tl, and Zn are indicating enrichments in FAs. The
remaining elements investigated in this study have no clear segregation between FAs and BAs. The mass balance
calculations point to Ca content of feed coal controlling the partitioning of elements in this power plant,
producing a high removal efficiency for highly volatile elements such as Hg, B and Se, and a high retention of
As, Bi, Cd, Cs, Ge, Pb, Rb, Sb, Sn, Tl and Zn in FAs. However, the high enrichment in trace elements of FAs
can increase the hazardous potential of this coal by-product. |
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