Modified on-line monitoring of total gaseous mercury in flue gases using Semtech Hg 2000 analyzer

摘要

The Semtech Hg 2000 analyzer continuously monitors the HgO content in flue"gas. An on-line measure- ment method of total gaseous mercury in flue gas devel- oped in our laboratory is described. which uses the ab- sorption cell of the Semtech Hg Analyzer connected to a converter that is located in a furnace heated up to 650°C. The converter can be heated up to 800 oC by both the fur- naceand an e~tra heating of a Ni-Cr alloy heating wire.. Both the absorption cell and the converter are made of quartz. All gaseous Hg2+ species in flue gas are thermally Teduced t9 HgO by the converter and detect~d by the semtech Hg 2000 anayzer.The thermal reduction efficiencies of different conversjon materials, which were filled in the converter, such as quartz chips, granular MgO, Ni and CoO powder. were tested using different flue gas conditions. Studies have shown that HCl is the major factor to inhibit the thefD1al reduction of Hg2+ to HgO, and in the.,converter arid the absorption cell HgO will react readily with HCl.toform HgCI2. Both MgO and Ni could be used in the converter to absorb HCl in the flue gas, but Ni has better absorption efficiency. By using an original Semtech and a modified one, both HgO and total gaseous Hg contents in flue gas could, be monitored si- mu'taneously and continuously.