Abstract:

Batch distillation is a highly energy inefficient process. To reduce its energy consumption, an internal heat integrated multivessel batch distillation with constant total reflux operation (IHIMVBD) is proposed for separation of binary mixtures. The rectifier surrounded by a jacketed reboiler concentrically is operated at a higher pressure compared to that in the jacketed reboiler, so the heat transfers from the high pressure rectification tower to the low pressure still through the internal wall. For this purpose, an isentropic compression system is installed in the reboiled vapor line. In order to improve the thermodynamic and economic performance, an intensified IHIMVBD (Int-IHIMVBD) scheme is developed by introducing overhead vapor recompression mechanism in the IHIMVBD structure. This scheme is to additionally utilize the latent heat of compressed overhead vapor for vaporizing the reboiler liquid. The features of the IHIMVBD system and its intensified form are illustrated by separating a binary mixture of ethanol and n-propanol. The Int-IHIMVBD configuration shows promising energy saving and economic potential over the IHIMVBD and MVBD.

Key words: multivessel batch distillation, total reflux, internal heat integration, vapor recompression, energy saving, economics, binary mixture

摘要：

鉴于间歇精馏热力学效率低的缺点,提出带有内部热集成的多储罐间歇精馏全回流操作(IHIMVBD)分离二元混合物的新型操作方式。在该操作中,多储罐间歇精馏塔被同轴的夹套式再沸器环绕,利用安装在再沸蒸汽管线上的压缩机使精馏塔的操作压力高于夹套式再沸器,使热量通过精馏塔壁面从高压的精馏塔传向低压的再沸器,实现热量的内部集成。为了进一步提高热力学效率和经济效益,将塔顶蒸汽再压缩技术应用于IHIMVBD,构成强化的内部热集成多储罐间歇精馏全回流操作(Int-IHIMVBD)。该操作能额外利用被压缩的塔顶蒸汽的潜热供给塔釜料液再沸,实现塔顶蒸汽与塔釜料液的热集成。通过模拟分离乙醇-正丙醇的实例表明,相比MVBD和IHIMVBD,Int-IHIMVBD能显著提高分离过程的热力学效率和经济效益。

关键词: 多储罐间歇精馏, 全回流, 内部热集成, 蒸汽再压缩, 节能, 经济, 二元混合物