短程蒸馏分离香茅油中的香茅醛实验及传质模型研究

Mass Transfer Model of Citronellal Separated from Citronella Oil by Short Path Distillation

短程蒸馏因具有受热时间短、分离效率高和可保持物质天然活性等优势,被广泛用于食品添加剂的提纯和精制。准确预测产品分离纯度以及分离效率对短程蒸馏工艺参数优化和设备设计有重要的意义。本文利用短程蒸馏分离了香茅油中香茅醛,并基于Langmuir-Kundsen方程建立了多组分传质模型,模拟了分离过程,预测了不同工艺条件对香茅醛分离纯度以及分离效率的影响,模拟结果与实验数据存在较好的一致性。研究结果表明:香茅醛的分离集中在蒸发器的前段,在蒸发器一半位置(z/L=0.5),香茅醛分离效率已达最终分离效率的60%以上。提高进料量、降低蒸发温度或减小蒸发面积均有利于香茅醛的纯化,但会降低其分离效率。综合香茅醛分离纯度以及分离效率,获得最佳工艺条件为:进料量4~5 m L/min,温度65~70℃。

The short path distillation has been widely used in purification and refining of food additives for its advantages of short heating time, high separation efficiency and preservation of the natural actives. Accurate prediction of separation purity and separation efficiency play an important role in parameters optimization and experiment design of short path distillation process. The citronellal was separated from citronella oil by short path distillation in this work and the corresponding multicomponent mass transfer model, which simulated the separation process, was established based on Langmuir-Kundsen equation. The effects of different process conditions on the purity and separation efficiency of citronellal were predicted, and the simulation results were consistent with the experimental data. The results showed that the separation of citronellal was mainly processed in the front, nearly middle part of the evaporator（z/L = 0.5）, with a ultimate separation efficiency of 60%. Increasing feeding rate, decreasing evaporating temperature or evaporation area was beneficial for the purification of citronellal, while reduced the separation efficiency. Based on the results of purity and separation efficiency of citronellal, the optimum process conditions were as follows： feeding rate, 4~5 m L/min; temperature, 65~70 ℃.