Methods for separating the binary azeotropic mixture of ethylene glycol and ethylene glycol diacetate with sulfolane entrainer

A method for separating ethylene glycol and ethylene glycol diacetate using sulfolane as an entrainer, wherein a yield of the ethylene glycol is greater than or equal to 99.50% and a mass purity of the ethylene glycol is greater than or equal to 99.50%, a yield of the ethylene glycol diacetate is greater than or equal to 99.80% and a mass purity of the ethylene glycol diacetate is greater than or equal to 99.90%, and the method comprises:

• (a) obtaining the ethylene glycol and a mixture of the ethylene glycol diacetate and the sulfolane through separating a mixture of the ethylene glycol and the ethylene glycol diacetate under an action of the sulfolane by an extractive distillation tower;
• (b) obtaining the ethylene glycol diacetate and the sulfolane through separating the mixture of the ethylene glycol diacetate and the sulfolane by an entrainer recovery tower;
• and
• (c) obtaining recycled sulfolane through cooling the sulfolane by a heat exchanger, mixing the recycled sulfolane with fresh sulfolane and circulating into the extractive distillation tower for recycling;
• wherein a theoretical plate count of the extractive distillation tower is 18-30, an operating pressure at a top of the extractive distillation tower is 7-8 kPa, a temperature at the top of the extractive distillation tower is 120-130° C., and a temperature at a bottom of the extractive distillation tower is 160-170° C.,
• a feeding position of the mixture of the ethylene glycol and the ethylene glycol diacetate is the 16th-18th theoretical plate of the extractive distillation tower, and a feeding position of the recycled sulfolane and the fresh sulfolane is the 6th-8th theoretical plate of the extractive distillation tower,
• a ratio of a total mass of the recycled sulfolane and the fresh sulfolane to a mass of the mixture of the ethylene glycol and the ethylene glycol diacetate is (5-7):1;
• a theoretical plate count of the entrainer recovery tower is 10-15, an operating pressure at the top of the entrainer recovery tower is 3-7 kPa, a temperature at the top of the entrainer recovery tower is 90-100° C., and a temperature at the bottom of the entrainer recovery tower is 160-175° C.,
• a feeding position of the mixture of the ethylene glycol diacetate and the sulfolane is the 4th-6th plate of the entrainer recovery tower;
• and
• a heat exchange temperature difference of the heat exchanger is 65-75° C., and an operating pressure of the heat exchanger is 15-20 kPa.