煤燃烧过程中铍的迁移转化特性研究

通过热力学平衡模拟计算煤燃烧过程中铍的形态转化,采用高温真空管式炉进行含铍化合物与矿物的固固反应实验,以及富铍煤中加入添加剂的燃烧实验,通过X射线衍射仪(XRD)、X射线荧光探针(XRF)以及电感耦合等离子质谱仪(ICP-MS)揭示煤燃烧过程中铍的迁移转化规律。结果表明,模拟计算发现铍只与含铝化合物反应生成BeAl_2O_4和Be Al6O10,同时固固反应实验也印证了这一结论,但反应温度在1 000℃左右,明显高于模拟计算温度650℃。添加Al_2O_3的富铍煤在燃烧时,由于铍与Al_2O_3发生反应,铍的释放率明显降低,最高降低33%以上;添加了伊利石的富铍煤,由于伊利石与铍的反应温度高于Al_2O_3,其抑制作用弱于Al_2O_3;而高岭石由于与铍的反应温度过高,在高岭石与铍发生反应产生抑制效果之前,部分铍已经在燃烧过程中释放出去,因此,抑制效果最差。

Investigation on the transfer-transformation behavior of beryllium during coal combustion

The thermodynamic equilibrium calculation was conducted to estimate the beryllium conversion in the combustion process of coal, and the high temperature vacuum tube furnace was used to research the beryllium compounds reaction with other solid substances and the coal combustion experiments by adding sorbents. X-ray diffraction (XRD), X-ray fluorescence probe (XRF) and inductively coupled plasma-mass spectrometry (ICP-MS) were used to reveal the transformation behavior of beryllium during coal combustion. The results indicate that the beryllium only reacts with aluminum compounds and the reaction resultants are BeAl₂O₄ and BeAl₆O₁₀, the solid-solid reaction experiments are in agreement with thermodynamic calculation results, but the actual reaction temperature is about 1000℃, far above the thermodynamic calculation temperature 650℃. Because beryllium reacts with Al₂O₃ in combustion, the release rate of beryllium in the coal sample added with Al₂O₃ reduces greatly by up to 33%. Moreover, the inhibition of illite to beryllium release for coal combustion with addition of illite is weaker owing to a higher reaction temperature of illite with beryllium than that of Al₂O₃. Kaolinite, because its reaction temperature with beryllium is too high, has the lowest inhibition effect.