淖毛湖煤热解过程中碱金属的迁移转化特性

Characteristics of alkali metal migration and transformation during pyrolysis of Naomaohu coal

基于Na,K盐含量控制对新疆低变质煤热解炼制油气品质的重要作用,通过建立固定床热解实验台,考察了淖毛湖煤在还原性气氛下热解温度对碱金属的迁移转化特性的影响。研究结果表明,淖毛湖原煤中Na主要以水溶态形式存在,K主要以不溶态形式存在。随着热解温度的升高,半焦收率呈先快速降低后缓慢降低的趋势,焦油收率呈先升高后降低的趋势。当热解温度低于600℃时,随着热解温度的升高,水溶Na向不溶Na转变;但当热解温度高于600℃时,不溶Na开始向水溶Na转化。在低温条件下,煤中的不溶K大量释放,酸溶K含量呈上升趋势;当温度高于600℃时,不溶K含量的下降速率减慢,水溶K含量增加。此外,热解释放的Na,K主要存在于焦油中,气体中含量相对较少。

Based on the importance of Na and K content control in the pyrolysis and refining of oil and gas from Xinjiang low metamorphic coal, the effect of temperature on the migration and transformation characteristics of alkali metals in reducing atmosphere of Naomaohu coal was investigated by the fixedbed pyrolysis experimental platform. The results show that Na in the raw coal is mainly in the form of water-soluble state, and K mainly exists in the form of insoluble state. With the increase of pyrolysis temperature, the char yield decreases rapidly and then decreases slowly and the tar yield increases firstly and then decreases. When the temperature is lower than 600 ℃, the water-soluble Na changes to insoluble state as the pyrolysis temperature increases. However, when the temperature is higher than600 ℃, the insoluble Na begins to transform into water-soluble Na. Under lower temperature, large numbers of insoluble K are released in the coal, and the content of acid soluble K is on the rise. When the temperature is higher than 600 ℃, the declining rate of insoluble K content becomes slow, and the water soluble K content increases. In addition, the releasing of Na and K mainly exist in the tar, while the contents are relatively less in gas.