Abstract:

Hydrofluoric acid (HF) alkylation is the main process of alkylbenzene production, and acid-hydrocarbon separator is one of the key equipment in the process. Due to the high corrosivity and high hazard of HF catalyst, the separation method of large tank sedimentation is still in use. As a result, the retention time of reaction effluents is long and the amount of HF reserves is large, which brings great risks to alkyl benzene units. There have been few researches on the separation of the system (both at home and abroad) due to the particularity of the medium. In this paper, a coalescence separator suitable for rapid separation of HF and alkylated oil was developed and pilot test was carried out. The acid content of oil phase outlet (≤0.2%) and the circulating acid concentration of acid phase outlet (≥98.5%) met the technological criterion. Moreover, the acid-hydrocarbon separation rate increased about 2 times, and the volume of separator and the amount of HF reserves shrank by more than 2/3. In view of the emulsification phenomenon of the reaction system, the emulsion yield and reduction rate were measured and calculated in the test, and the multi-layer boundary distribution of acid, hydrocarbon and emulsion layer in the separator was elucidated, which provides a good guide for the upgrading and transformation of HF catalytic process.

Key words: alkylation, alkylbenzene, hydrofluoric acid, fiber coalescence, acid-hydrocarbon separation

摘要：

氢氟酸（HF）烷基化是烷基苯生产的主流工艺，酸烃分离器是该工艺的关键设备之一，由于HF催化剂的高腐蚀性、高危险性，至今仍沿袭大罐沉降的分离方法，导致反应流出物停留时间长、HF储量巨大，给烷基苯装置带来巨大的安环风险。工艺介质的特殊性造成国内外对该体系快速分离的研究处于空白，本文创新开发了适用于HF和烷基化油快速分离的聚结分离器，开展了中试试验，分离器油相出口酸含量（≤0.2%）及酸相出口循环酸浓度（≥98.5%）满足工艺指标，酸烃分离速率可提高约2倍，分离器容积及HF储量缩减2/3以上，同时针对该反应体系的乳化现象，试验测算了乳化液产率及消减速率，解决了分离器内酸、烃、乳化层的多层界位分布状况不明晰的难题，对涉及HF催化工艺的升级改造具有普遍参考价值。

关键词: 烷基化, 烷基苯, 氢氟酸, 纤维聚结, 酸烃分离