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- Feng, Xinbin, et al.
(författare)
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Modified on-line monitoring of total gaseous mercury in flue gases using a Semtech 2000 Analyzer
- 2000
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Ingår i: Fresenius Journal of Analytical Chemistry. - 0937-0633. ; 368:5, s. 528-533
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Tidskriftsartikel (refereegranskat)abstract
- The Semtech Hg 2000 analyzer continuously monitors the Hg0 content in flue gas. An on-line measurement method of total gaseous mercury in flue gas developed in our laboratory is described, which uses the absorption 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 °C by both the furnace and an extra 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 reduced to Hg0 by the converter and detected by the Semtech Hg 2000 analyzer. The thermal reduction efficiencies of different conversion 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 thermal reduction of Hg2+ to Hg0, and in the converter and the absorption cell Hg0 will react readily with HCl to form HgCl2. 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 Hg0 and total gaseous Hg contents in flue gas could be monitored simultaneously and continuously.
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- Feng, Xinbin, et al.
(författare)
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On-line Speciation of Mercury in the Flue Gases
- 1999
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Ingår i: Proceedings of A&WM Mercury in the Environment Specialty Conference, Air & Waste Management Association, Minneapolis, MN. USA.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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- Lindstedt, Anja, et al.
(författare)
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High temperature catalytic reduction of nitrogen monoxide by carbon monoxide and hydrogen over La1-xSrxMO3 perovskites (M=Fe,Co) during reducing and oxidizing conditions
- 1994
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Ingår i: Appl Catalysis A. - 0926-860X. ; 116:1-2, s. 109-126
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic activity of La1−xSrxMO3 perovskites (M = Fe or Co) was investigated for the reduction of nitrogen monoxide. The catalytic activity for the NO+CO and the NO+H2 reaction was investigated in a fixed bed reactor in the temperature interval 873–1223 K. The perovskites showed high activity for the reduction of nitrogen monoxide in the absence of oxygen even at 873 K. Hydrogen was less active than carbon monoxide as a reducing agent and the cobalt perovskites showed slightly higher activity than the iron perovskites in the lower temperature range. The reduction of nitrogen monoxide was concluded to proceed through the reduction of the surface by the reducing agent followed by adsorption and decomposition of nitrogen monoxide on the surface. The activated (reducing) perovskites were investigated by X-ray diffractometry. The cobalt perovskites were reduced to a compound of the K2NiF4 type, La2CoO4, while the iron perovskites retained their perovskite structure upon reduction. The perovskite structure of the cobalt perovskite was restored upon reoxidation of the La2CoO4 compound. The introduction of excess oxygen into the gas mixture decreased the nitrogen monoxide reduction level to zero. Nitrogen monoxide (1000 ppm) was completely reduced in a stoichiometric CO+O2 mixture (2% CO and 1% O2) over La0.8Sr0.2CoO3 at 1173 K. LaCoO3 showed high thermal stability in a helium atmosphere at 300–1223 K, while the perovskite was reduced to La2O3 and cobalt metal in a 10% CO+ He atmosphere.
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- Åmand, Lars-Erik, 1957, et al.
(författare)
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Co-Combustion of Dried Sewage Sludge and Coal The Fate of Heavy Metals
- 2001
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Ingår i: In Proceedings of the 16th International Conference on Fluidized Bed Combustion--FBC01, held in Reno, Nevada, USA, May 13-16, 2001.
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Konferensbidrag (refereegranskat)abstract
- The fate of some selected heavy metals has been investigated during co-combustion of sewage sludge and coal in two fluidised bed combustors: the 12MWth circulating fluidized bed (CFB) boiler at CTH and the laboratory scale unit at IVD. The total and species balances were, in general, fairly well closed, and the increased amounts of heavy metals originating from the input sludge were also found in the exit flows. Volatile species such as Hg and Cd are sensitive to the temperature conditions. Thus, almost no mercury was found in the bottom ash, and a cyclone at 350 °C captured little Hg in comparison to a cyclone and filters at 150 °C. The high particle loading in a CFB appears to contribute essentially to the reduction of the flue gas mercury concentration; the emission is reduced by orders of magnitude compared to a plant with low particle concentration. In most cases investigated the emissions of heavy metals were below the limits related to co-combustion set by the European Union.
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