Energy-saving method for separating methylbenzene and 2-methoxyethanol mixture by extractive distillation

Abstract

The invention discloses an energy-saving method for separating a methylbenzene and 2-methoxyethanol mixture by extractive distillation. An extracting agent for the energy-saving method is dimethyl sulfoxide; the used separating equipment comprises an extractive distillation column, a heat exchanger and an extracting agent recovering tower; in the separating process, methylbenzene steam generated on the top of the extractive distillation column is condensed and then is extracted according to the preset reflux ratio; 2-methoxyethanol and the extracting agent at the bottom of the extractive distillation column are extracted and then are divided into a circulating material flow and a discharging material flow; the circulating material flow is heated by the heat exchanger and then returns to enter the extractive distillation column; the discharging material flow enters the extractive distillation column; the extracting agent is extracted from the bottom of the extracting agent recovering tower and is recycled; and 2-methoxyethanol steam generated on the top of the extracting agent recovering tower is condensed by the heat exchanger and then is extracted according to the preset reflux ratio. According to the method, a double-effect heat-integration technique is adopted, and heat is provided for to-be-reboiled material flow at the bottom of the extractive distillation column by usinga to-be-condensed material flow on the top of the extracting agent recovering tower, so that secondary utilization of energy is realized, energy consumption is effectively reduced and the cost of equipment is reduced.

Description

technical field [0001] The invention belongs to the technical field of extraction, rectification and separation, and relates to a method for separating a mixture of toluene and 2-methoxyethanol, in particular to an energy-saving method for separating the mixture of toluene and 2-methoxyethanol through extraction and rectification. Background technique [0002] Toluene is an extremely important synthetic raw material and organic solvent in the chemical industry. As a raw material, it is used to prepare chemicals such as benzene and xylene, and can also be used in the production of fine chemicals such as spices. It is widely used in chemical, pharmaceutical, pigment and synthetic material industries. As a solvent, it is used in printing and dyeing, coating and electrochemical industries. 2-Methoxyethanol is mainly used as a solvent for oils, nitrocellulose, synthetic resins, alcohol-soluble dyes, etc., as well as a pesticide dispersant and a leather plasticizer. In the above...

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Problems solved by technology

Li et al. (Computers&Chemical Engineering, 2017,99:117.) designed the process of extractive distillation to separate toluene and 2-methoxyethanol, but the product purity and yield are low, and the process consumes a lot of energy

Sun Chang (Research on the separation of toluene / ethylene glycol monomethyl ether by batch extraction and rectification [D]. Tianjin University, 2013.) designed a process for the separation of toluene and 2-methoxyethanol by batch extraction and rectification, but the reflux ratio is extremely Large (9) and the toluene product has a low purity, only 98.8%, and has the disadvantages of high energy consumption and low product purity

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