System and method for separating methanol-water through rectification coupled membrane

Abstract

The invention discloses a system for separating methanol-water through a rectification coupled membrane. The system comprises a rectification tower, a condenser, a reboiler, a centrifugal pump and a membrane separator. A method for separating methanol-water by using the system comprises the following steps that: a mixture of methanol and water is introduced into the rectification tower, most of water is separated from the tower kettle of the rectification tower, and residual water and methanol mixed gas is distilled out from the tower top of the rectification tower; and the residual water and methanol mixed gas is introduced into the condenser for condensation, part of the residual water and methanol mixed liquid obtained after condensation flows back into the rectification tower, the rest part of the residual water and methanol mixed liquid enters the membrane separator after being pressurized through the centrifugal pump, and finally high-purity methanol is obtained. According to the method, a low-concentration methanol solution is firstly purified in the rectification tower to a relatively high concentration, and then methanol and water are further separated through a monopolar pervaporation membrane, so that the concentration of penetrating fluid methanol is increased to 99.9% or above, cascade separation of methanol with different concentrations is realized, the energy consumption in the separation process is greatly reduced, and the investment and the cost in the separation process are saved.

Description

technical field [0001] The invention belongs to the technical field of rectification coupling membrane separation, and in particular relates to a system and method for rectification coupling membrane separation of methanol-water. Background technique [0002] The increasing amount of greenhouse gases in the air makes the trend of global warming more and more obvious. Methanol is an important carrier for energy storage and conversion. Because methanol has the characteristics of low boiling point and high octane number, it has the characteristics of high oxygen content and weaker calorific value than gasoline as a fuel, and its latent heat of vaporization is more than three times that of gasoline. At the same time, since the physical and chemical properties of methanol fuel are close to that of gasoline, using methanol fuel on gasoline engines does not require major changes to the engine. Methanol and gasoline have good compatibility, and various proportions of blending can b...

AI Technical Summary

Problems solved by technology

Industrial-grade methanol has high purity requirements, so it can be used as fuel or to produce various downstream products, so it has relatively high separation requirements. Through multi-tower rectification, methanol with a purity of more than 99.9% can be obtained, but the energy consumption of multi-tower rectification and separation is high. At the same time, the investment cost is high

Images