精馏是利用混合物中各组分挥发度不同而将各组分加以分离的一种分离过程，常用的设备有板式精馏塔和填料精馏塔。精馏的原理及设备流程与普通精馏相同，只是待分离物系中的组分间的相对挥发度较小(<1.05~1.10),因而采用填料以实现待分离组分的分离提纯。在单离香料的生产原料一天然精油中经常有同分异构体并存的情况，例如在香叶油、玫瑰油、玫瑰草油等天然精油中同时存在的香茅醇和玫瑰醇就是旋光异构体。

工作原理：精馏通常在精馏塔中进行，气液两相通过逆流接触，进行相际传热传质。液相中的易挥发组分进入气相，气相中的难挥发组分转入液相，于是在塔顶可得到几乎纯的易挥发组分，塔底可得到几乎纯的难挥发组分。料液从塔的中部加入，进料口以上的塔段，把上升蒸气中易挥发组分进一步增浓，称为精馏段；进料口以下的塔段，从下降液体中提取易挥发组分，称为提馏段。从塔顶引出的蒸气经冷凝，一部分凝液作为回流液从塔顶返回精馏塔，其余馏出液即为塔顶产品。塔底引出的液体经再沸器部分气化，蒸气沿塔上升，余下的液体作为塔底产品。塔顶回流入塔的液体量与塔顶产品量之比称为回流比，其大小会影响精馏操作的分离效果和能耗。

Distillation is a separation process that uses the different volatility of each component in the mixture to separate each component. Commonly used equipment includes a plate rectification tower and a packed rectification tower. The principle and equipment flow of rectification are the same as ordinary rectification, except that the relative volatility between the components in the system to be separated is small (<1.05~1.10), so packing is used to realize the separation and purification of the components to be separated. There are often isomers coexisting in natural essential oils, the raw material for the production of isolated fragrances. For example, citronellol and roseol that co-exist in natural essential oils such as geraniol oil, rose oil and palmarosa oil are optical isomers. body.

Working principle: Distillation is usually carried out in a rectification tower, and the gas and liquid phases are contacted by countercurrent to conduct heat and mass transfer between phases. The volatile components in the liquid phase enter the gas phase, and the hardly volatile components in the gas phase transfer to the liquid phase, so that almost pure volatile components can be obtained at the top of the tower, and almost pure hardly volatile components can be obtained at the bottom of the tower. The feed liquid is added from the middle of the tower. The tower section above the feed port further enriches the volatile components in the rising vapor, which is called the rectification section; the tower section below the feed port extracts the volatile components from the descending liquid Divide, called the stripping section. The vapor drawn from the top of the tower is condensed, a part of the condensate is returned to the rectification tower from the top of the tower as reflux, and the remaining distillate is the top product. The liquid drawn from the bottom of the tower is partially vaporized by the reboiler, the vapor rises along the tower, and the remaining liquid is used as the bottom product of the tower. The ratio of the amount of liquid flowing back into the tower from the top of the tower to the amount of product at the top of the tower is called the reflux ratio, and its size will affect the separation effect and energy consumption of the rectification operation.