Partitioning of trace inorganic elements in a coal-fired power plant equipped with a wet Flue Gas Desulphurisation system

Evaluation of a Flue Gas Desulphurisation (FGD)-Gypsum from a Wet Limestone FGD as Adsorbent for Removal of Selenium in Water Streams

“…A sketch of the FGD system at the coal-fired power plant is shown in Figure 1. Detailed descriptions of the operation of the FGD system at the coal-fired power plant and the water streams are provided [7,9].…”

“…Conversely, above pzc the surface is negatively charged (attracting cations/repelling anions). Therefore, the acidic conditions of gypsum slurry aqueous phase (pH 5.1) [9] induced by the addition of Al 2 (SO 4 ) 3 , led to the protonation of the FGD-gypsum surface.…”

“…Because coal-combustion processes are well evaluated, general trends in trace element behaviour during combustion have been identified [1][2][3][4][5][6][7][8][9]. It is common knowledge that many of the trace elements from coal are partially or totally vaporised during combustion.…”

“…The degree of vaporisation determines how each element is partitioned between various solid residues and the flue gas [1]. Selenium during Pulverised Coal Combustion (PCC) can be released as gas SeO 2 and/ or as particulate Se [7][8][9]. However, when the flue gas cools down some of gas SeO 2 may condense on the finest particle surfaces of Fly Ashes (FAs).…”

“…Most of FAs are captured in cleaning systems by high-efficiency particulate collector devices, though some particulate Se may escape from controls and reach Flue Gas Desulphurisation (FGD) system. Once in FGD, gas SeO 2 and particulate Se may be dissolved in the aqueous phase of absorber slurries and/or concentrated in the gypsum sludge [7][8][9]. Depending on the abatement capacity of FGDs, a given proportion of Se can be released in a gaseous and/or PM form [8,9].…”