低表面张力物系在规整填料塔中的传质性能

为了研究低表面张力物系在高比表面积的规整填料塔中的流体力学性能和传质性能,选用正庚烷-甲基环己烷物系,在内径400mm的不锈钢精馏塔中对Mellapak 500Y和750Y型规整填料进行全回流精馏实验。通过测定气相负荷从小到大直至液泛的过程,得到了不同操作条件下的压降、泛点气速、传质效率的数据,给定了操作的极限。结果表明:750Y填料的传质效率优于500Y填料,但稳定性比500Y填料差,处理量比500Y填料小。且实验中气相负荷递增变化时的传质效率略低于气相负荷递减变化时的传质效率。同时,为了考察传质效率随塔高的变化,填料塔在不同高度处设置了4个取样口,测定了不同取样口中样品的组成。通过分析传质效率随塔高的变化,阐述了不同负荷范围内气相总体积传质系数沿塔高的变化规律。

Mass transfer of low surface tension system in packed column containing structured packings

To investigate the hydrodynamics and mass transfer performance of low surface tension system in a column with structured packings, distillation experiments were carried out at total reflux using n-heptane/methylcyclohexane system in a stainless steel distillation column containing Mellapak 500Y and 750Y. The inner diameter of the column was 400mm. Experiments were conducted in a wide range of flow rate. The flooding experiment data, which could give the limits of operation, was determined. The key parameters, including pressure drop, flooding factor, and mass transfer efficiency, were obtained. Compared with 500Y, 750Y exhibited higher mass transfer efficiency, lower stability and smaller capacity. If experiments conducted with vapor load in ascending order, mass transfer efficiency was slightly lower than that measured by descending order. In order to study the variation of mass transfer efficiency along the tower, four sampling outlets were set up at different heights. The compositions of samples were determined. Through the analysis of mass transfer efficiency along the column, the relationship between overall gas phase volume mass transfer coefficient and tower height was determined at various vapor loads.