Abstract: A novel process of three-column distillation was proposed for the purification of synthetic methanol. In the new process with double-effect distillation to realize heat-integration, the feed to the lower-pressure column was a side-stream with moderate methanol concentration drawn from a stage of the higher-pressure column above its feed stage.A better balance of separation duty between the higher-and lower-pressure columns was achieved, which reduced further the total heat consumption of double-effect distillation process.The salt and base components from the pretreatment column were separated and concentrated to the bottom stream of the higher-pressure column so that the bottom stream of the lower-pressure column contained>99.9% water. Then the water was recycled to the pretreatment column as the extracting water, which realized water-integration within the process and reduced the consumption of fresh soft water of the process. A comparative case study by steady-state simulation was carried out between the traditional two-column process (A), the present three-column process (B) and the new process (C). The result showed that process (C) reduced the heat consumption by 49.2% of process (A) or by 24.7% of process (B) and reduced the soft-water consumption by 38.0% of both (A) and (B).

摘要： 提出了一种新的三塔精馏工艺用于合成甲醇的精制过程.在采用差压双效精馏实现系统内的热集成方案中，新工艺从加压精馏塔进料板上部的侧线采出中等甲醇浓度的物料作为常压精馏塔的进料，有效地平衡了两塔的分离负荷，进一步降低了双效精馏的总能耗，同时，将预精馏塔产生的盐碱类物质浓缩分离到加压塔底采出，使常压塔底出料为高纯度软水，将其循环复用为预塔萃取水，实现了系统内的工艺软水集成，不但降低了新鲜工艺软水的消耗，而且还减少了系统的废水排放量.运用计算机稳态模拟方法对传统的两塔工艺、现有的三塔双效精馏工艺和本文提出的新工艺进行了对比研究，研究结果表明：新工艺可以比两塔工艺节能49.2%，节水38.0%;比现有三塔工艺节能24.7%，节水38.0%.