煤热解过程中无机有害元素的变迁规律

在自行设计的加压密闭快速热解反应器中研究了神华和义马煤中Na、K、Pb和Mn等无机有害元素在氮气条件下随温度（300℃-700℃)的变化规律,进一步考察了热解气氛（氮气、氢气和二氧化碳）、压力对神华煤中这4种元素逸出规律的影响。结果表明：Na、K、Pb和Mn等元素在半焦中的残留量随温度的升高而减少,减少量随煤种而异,如在700℃时,神华煤中Na、K、Pb和Mn的析出率分别是义马煤的3、4．2、1．4和2．4倍;低压快速加氢热解有利于这4种元素的逸出。Pb是挥发性最强的元素,与热力学计算结果一致。

Transformation of Na,K, Pb and Mn during pyrolysis of coal

Transformation of Na, K, Pb and Mn in char for Shenhua and Yima coals at pyrolysis temperatures of 300 degrees C-700 degrees C was reported. Effects of atmosphere (N2, H2 and CO2) and pressure on release of the elements in Shenhua coal were also studied. The pyrolysis experiment was carried out in a closed stainless steal reactor. Results show that the bleeding ratio of Na, K, Pb and Mn varied with coal type but all increased with pyrolysis temperature. For example, the bleeding ratio of Na, K, Pb and Mn at 700 degrees C for Shenhua coal was 3, 4.2, 1.4, and 2.4 times larger than that of Yima coal. The effect of pressure was small. Among the N2, H2 and CO2 environments, H2 resulted in the highest bleeding ratio and CO2 the least bleeding ratio. Thermodynamic calculation shows that Pb was the most volatile element among the four inorganic harmful elements.