昭通褐煤的热解提质及其对气化反应性能的影响

为了对储量相对丰富的昭通褐煤进行合理有效的分级转化利用,采用固定床程序升温热解的方法研究了不同温度下煤的热解行为,借助GC-MS和拉曼光谱对所得焦油和煤焦进行了表征分析,并在850℃下对不同热解温度制得的煤焦进行了水蒸气等温气化特性评价。结果表明,热解温度为700℃时,热解气体有效组分(H_2、CO、CH_4)的累积物质的量占总释放量的70%,此温度下热解气低位热值增长速率最快(以500℃下热解气低位热值为基准计算,其值为90%);酚类化合物在500-700℃大量生成析出,而温度高于700℃时,酚类化合物的分解反应加剧。不同热解温度下所制煤焦的表观气化反应速率随热解温度的升高不断降低,气化产物中CO_2与CO的物质的量逐渐升高,700℃热解制得的煤焦在水蒸气气氛下气化所得合成气中有效组分H_2与CO的比率最高。

Upgrading of Zhaotong coal by pyrolysis and its effect on the gasification reactivity

In order to integratedly utilize the relatively rich coal resource of Zhaotong mine, temperature-programmed pyrolysis experiments of Zhaotong lignite were performed in fixed bed reactor at different temperatures. The resultant coal tar and char were characterized by GC-MS and Raman Spectroscopy, respectively. Char-H₂O isothermal gasification characteristics were evaluated in fixed bed reactor at 850℃. The results show that in pyrolysis at 700℃ the cumulative content of H₂, CO and CH₄ in gases accounts for about 70%, and the growth rate of low calorific value of gas is the fastest, which is 90% based on the value at 500℃. A large number of phenolic compounds are generated at 500-700℃. Above 700℃ the decomposition reactions of the phenolic compounds is intensified. With the increase of pyrolysis temperatures, the apparent reaction rate of char decreases, while the molar ratio of CO₂ and CO increases. The molar ratio of H₂ and CO in gasification from char pyrolyzed at 700℃ was the highest.