Enrichment and separation method of low-concentration dimethyl oxalate

According to the enrichment and separation method of the low-concentration dimethyl oxalate provided by the invention, the bottom liquid of the desorption tower is circulated back to the absorption tower, so that the dimethyl oxalate is enriched to a certain concentration and then enters the rectification tower to be separated, the separation energy consumption of the dimethyl oxalate is greatly reduced, and meanwhile, the cyclic utilization of a methanol absorbent is realized. Aiming at different reaction working conditions, the concentration of the enriched dimethyl oxalate can be flexibly adjusted, so that the amount of the outwards thrown dimethyl oxalate and methanol solution can be adjusted, the treatment capacity of the dimethyl oxalate rectifying tower is further adjusted, and the flexibility of the flow is high. 本发明提供了一种低浓度草酸二甲酯的富集分离方法，通过将解吸塔底液循环回吸收塔，使草酸二甲酯富集到一定浓度后再进入精馏塔分离，大幅降低了草酸二甲酯的分离能耗，同时实现甲醇吸收剂的循环利用。本发明针对不同反应工况，草酸二甲酯富集的浓度可以灵活调节，从而可以调节外甩的草酸二甲酯、甲醇溶液的量，进而调节草酸二甲酯精馏塔的处理量，流程的灵活性高。