准东煤中碱金属的赋存形式及其在燃烧过程中的迁移规律实验研究

对新疆煤采用三步化学提取实验(蒸馏水洗、醋酸铵洗、稀盐酸洗)以分析其碱金属赋存特性,对水溶的阴离子进行了离子色谱分析。分别检测了在不同温度、不同停留时间下准东煤灰的碱金属量,并用Factsage软件模拟该煤灰中碱金属的析出形式。结果表明,煤中的钠主要是水溶钠,钾主要以不可溶钾存在,水溶碱金属主要以水合离子形式的氯化物存在。准东煤中碱金属在400~600℃析出最快,主要是水溶态碱金属的释放,碱金属的释放主要发生在燃烧后期。灰中碱金属在高温下会与烟气中的成分发生反应,主要产物是氯化物以及氢氧化物。在700℃钠对准东煤中低温共融物的形成有很大贡献。

Modes of occurrence and transformation of alkali metals in Zhundong coal during combustion

The sequential chemical extraction (three steps) was used to examine the modes of occurrence of alkali metals in four kinds of Xinjiang coals based on the solubility in distilled water, ammonium acetate and hydrochloric acid. The water-soluble anions were analysed by ion chromatography. The contents of alkali metals in the coal ash made at different temperatures and residence times were measured respectively, and the release forms of alkali metals from coal ash were also simulated by Factsage. Results show that the most of sodium in coal is the water-soluble one and the potassium only exists in the insoluble form. Water-soluble alkali metals may exist in the form of hydrated ion of chloride. The release of alkali metals from coal is the fastest during 400~600 ℃,which are mostly water-soluble alkali metals; and the release of alkali metals mostly occurs at the later stage of combustion. Alkali metals in ash would react with the components of flue gas at high temperature, which produces chloride and hydroxide. It can be inferred that the sodium makes a great contribution to the formation of low temperature eutectoid at 700 ℃.