The combustion process releases many organic and inorganic pollutants into the atmosphere, both in gaseous and solid form. During coal combustion in thermal power plants without pollution control equipment, chlorine, fluorine, bromine, and iodine present in coals are mainly volatilized as gaseous compounds. It has been estimated (1) that 94% of the chlorine in coal is volatilized, generally being emitted as gaseous HCI. Emission values of 99% for chlorine, 90% for fluorine, 60% for bromine, and 90% for iodine have been given for pulverized coal combustion based on actual measurements at the 600 Mwe power station in Netherlands (2). Limiting pollutant emissions is a precise requirement of the Italian legislation that fixes (in the case of power plants) 100 mg/Nm3 as the limit value for chlorine, and 5 mg/Nm3 for fluorine and bromine (expressed as hydrofluoric and hydrobromic acid, respectively). No limit for iodine emissions has been established. From this point of view and in order to maintain control of emissions from combustion plants, it is important to monitor the concentration of halogens in fuels. Unfortunately, in literature there are very few data published with regard to the amount of halogens in fossil fuels, which emphasizes the analytical difficulties with regard to the determination of these analytes. In the present paper, a pyrohydrolysis of the sample at 1100°C, followed by the absorption of volatilized compounds in Na2CO3/NaHCO3 solution and the final instrumental analysis of Cl, Br, and F with ion chromatography (IC) and Br and I with inductively coupled plasma mass spectrometry (ICP-MS) has been adopted. The accuracy of the method, evaluated by analyzing some certified reference materials, was better than 95% for all analytes and the detection limits adequate to the analytical requirements (0.1 mg/kg for Br and I, 1 mg/kg for F, and 10 mg/kg for C1).
|Number of pages||6|
|Publication status||Published - Jul 2002|
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