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Chromium Speciation in Coal and Biomass Co-Combustion Products

机译：煤和生物质共燃产品中的铬形态

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Chromium speciation is vital for the toxicity of products resulting from co-combustion of coal and biomass. Therefore, understanding of formation processes has been studied using a combination of X-ray absorption fine structure (XAFS) spectroscopy and thermo-dynamic equilibrium calculations. The influence of cofiring on Cr speciation is very dependent on the type of fuel. Cr(VI) contents in the investigated fly ash samples from coal and coining average around 7% of the total chromium. An exception is cofiring 7-28% wood for which ashes exhibited Cr(VI) concentrations of 12-16% of the total chromium. Measurements are in line with thermodynamic predictions: RE factors of Cr around 1 are in line with volatile Cr only above 1400 ℃; lower Cr(VI) concentrations with lower oxygen content and Cr(III) dissolved in aluminosilicate glass. Stability of Cr(VI) below 700 ℃ does not correlate with Cr(VI) concentrations found in the combustion products. It is indicated that Cr(VI) formation is a high-temperature process dependent on Cr evaporation (mode of occurrence in fuel, promoted by organic association), oxidation (local oxygen content), and formation of solid chromates (promoted by presence of free lime (CaO) in the ash). CaCrO_4(s) is a probable chemical form but, given different leachable fractions (varying from 25 to 100%), different forms of Cr(VI) must be present Clay-bound Cr is likely to dissolve in the aluminosilicate glass phase during melting of the clay.
机译：铬的形态对于煤和生物质共同燃烧产生的产品的毒性至关重要。因此，已经结合使用X射线吸收精细结构（XAFS）光谱学和热力学平衡计算来研究对形成过程的理解。共燃对Cr形态的影响非常取决于燃料的类型。研究的煤粉煤灰样品中的Cr（VI）含量平均约为总铬的7％。一个例外是共烧7-28％的木材，其灰烬的Cr（VI）浓度占总铬的12-16％。测量结果符合热力学预测：1左右的Cr的RE因子仅在1400℃以上才与挥发性Cr一致。较低的Cr（VI）浓度和较低的氧含量以及溶解在铝硅酸盐玻璃中的Cr（III）。低于700℃的Cr（VI）的稳定性与燃烧产物中的Cr（VI）浓度无关。结果表明，Cr（VI）的形成是一个高温过程，取决于Cr的蒸发（在燃料中的发生方式，由有机缔合促进），氧化（局部氧含量）和固体铬酸盐的形成（由游离铬的存在促进）。灰中的石灰（CaO）。 CaCrO_4是一种可能的化学形式，但是，考虑到不同的可浸出部分（从25％到100％），必须存在不同形式的Cr（VI）粘土结合的Cr在熔化过程中很可能溶解在铝硅酸盐玻璃相中。黏土。

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  • 来源
    《Environmental Science & Technology》 |2011年第6期|p.2450-2456|共7页
  • 作者

    Arthur F. Stam; Ruud Meij; Henk te Winkel; Ronald J. van Eijk; Frank E. Huggins; Gerrit Brem;

  • 作者单位

    KEMA, P.O. Box 9035, 6800 ET Arnhem, The Netherlands,University of Twente, Faculty of Engineering, Laboratory of Thermal Engineering, P.O. Box 217,7500 AE Enschede, The Netherlands;

    KEMA, P.O. Box 9035, 6800 ET Arnhem, The Netherlands;

    KEMA, P.O. Box 9035, 6800 ET Arnhem, The Netherlands;

    KEMA, P.O. Box 9035, 6800 ET Arnhem, The Netherlands;

    University of Kentucky, 107 S. J. Whalen Building, 533 S. Limestone St., Lexington, Kentucky 40506-0043, United States;

    University of Twente, Faculty of Engineering, Laboratory of Thermal Engineering, P.O. Box 217,7500 AE Enschede, The Netherlands;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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