从煤焦油分离提纯蒽和咔唑工艺改进探讨

Improvement of separation and purification process for anthracene and carbazole from coal tar

溶剂结晶-精馏法是目前从煤焦油中分离提纯蒽和咔唑的比较先进成熟的已工业化工艺,其杂质的脱除主要在溶剂结晶部分,操作步骤多,但杂质分离效果还不是很理想,最终影响产品纯度。通过实验研究,发现结晶物中高杂质母液的滞留是该工艺杂质分离效果难以提高的关键因素。提出了溶剂结晶结合抽滤-精馏法新工艺,给结晶箱组合气液分离器,实现结晶同步抽滤功能,降低结晶物的母液滞留量,可提高分离效果,减少溶剂循环量,提高产品纯度和回收率,降低装置能耗,增加产能,有较好的经济性。

A relatively advanced industrialized method used for separation and purification of anthracene and carbazole from coal tar is crystallization-distillation process. The impurities are mainly removed by the crystallization process. However, the separation and purification of crystallization process need to be further improved because of too many steps and relatively poor separation effect. In addition, the experimental results indicate that the retention of mother liquor with high content of impurities in crystals is the key factor that greatly influences the improvement of the separation of anthracene and carbazole from coal tar. Therefore, a new process of crystallization and filtration-distillation is proposed in this paper. In the new process, crystallizer is combined with gas-liquid separator to achieve the synchronization of crystallization and suction filtration, which can improve separation efficiency by reducing the retention of mother liquor in crystallization, and obtain the high purity and recovery rate of the product with a small amount of solvent circulation. This new process is promising and economical ,with low energy consumption and large production capacity.