流化床热解过程中煤中氟的挥发性研究

VOLATILITY OF FLUORINE IN COAL DURING FLUIDIZED-BED PYROLYSIS

采用大同、平朔、霍林河、义马四种煤研究了热解过程中煤中氟的挥发行为。研究表明 ,随热解温度的升高 ,氟的挥发率有增加趋势。但其行为不仅取决于元素氟及其化合物本身的挥发性 ,同时还受其赋存形态、共存矿物离子等原生条件和热解条件的影响。氟磷灰石类矿物质并非四种煤中氟的主要赋存形态。除大同煤外 ,难挥发性氟的含量均高于 6 5 %,难挥发性氟至少部分是以CaF2 或CaF2 基的多元络合物形式存在的。

Fluorine is one of the harmful trace elements in coal. In this paper, the properties of fluorine in coal and its volatility during fluidized-bed pyrolysis were studied. In the coal samples studied, fluorapatite is not the major form of fluorine. During coal pyrolysis, the volatility of fluorine can be affected by not only the volatility of the individual element and its compounds, but also the form of fluorine and the pyrolysis conditions. With increasing temperature, the volatility of fluorine in coal increases. In the experiment temperature ranges, fluorine volatility has gone up from 20% to 50% for Datong coal, from 17% to 34% for Pingshuo coal, from 18% to 30% for Huolinhe coal, and from 10% to 25% for Yima coal. The mass fraction of non-volatile form of fluorine in these coals is higher than 65% except for Datong coal. The non-volatile form of fluorine in coal might be calcium fluoride or calcium fluoride based complex compounds.