Membrane distillation dehydration method for polyatomic alcohol water solution produced from corn

Abstract

The invention discloses a method for dehydrating polyol aqueous solution produced from corn, which belongs to the application technology of vacuum membrane distillation. The method adopts a membrane distillation device, first heats the polyol aqueous solution to a temperature of 61°C-65°C, and then uses a raw material pump to add the polyol aqueous solution into the hollow fiber membrane to form a vacuum environment of 0.085MPa-0.089MPa outside the membrane, thereby A vapor pressure difference is formed on both sides of the membrane. The water in the polyol aqueous solution inside the membrane enters the hollow fiber membrane through the membrane holes in the form of steam under the action of the vapor pressure difference, and then condenses into Water, collecting condensed water, so as to achieve dehydration and concentration of polyol aqueous solution produced from corn. The invention has the advantages of operating temperature below 65 DEG C, lower energy consumption compared with the existing common distillation method, high interception rate of polyalcohol by the membrane used, and low loss rate of polyalcohol.

Description

technical field [0001] The invention relates to a method for dehydrating polyol aqueous solution produced from corn, and belongs to the application field of vacuum membrane distillation technology. Background technique [0002] Low-carbon polyols such as ethylene glycol and propylene glycol (including 1,2-propanediol and 1,3-propanediol) are important energy liquid fuels, and are also a very important raw material for polyester synthesis, such as for the manufacture of polyethylene naphthalate Polyester fibers such as glycol ester (PEN), polytrimethylene terephthalate (PTT), etc. In 2005, my country's import dependence of ethylene glycol was as high as 78.6%, which was the highest record in import history in recent years. The domestic production scale of propylene glycol is very small, and the products mainly rely on imports. Therefore, it is of great significance to research and develop new routes and new methods for the synthesis of ethylene glycol and propylene glycol. ...

AI Technical Summary

Problems solved by technology

Dehydration treatment of polyol mixed solution by ordinary distillation and rectification has the problems of large investment in one-time equipment, high operating cost, and unstable operation.

This is because water has a lower boiling point than polyols, and a large amount of steam must be consumed to evaporate water from polyols; although multiple-effect distillation is used, the energy consumption is still high; in order to achieve the effect of multiple-effect evaporation, each dehydration unit The operating pressure of the tower decreases, resulting in a large amount of low-pressure water vapor at the top of the vacuum-operated tower, resulting in huge cooling equipment and operating costs, and brings great difficulties to the vacuum maintenance of the tower; because the multi-effect operation is limited within a certain pressure range , the operating pressure difference and temperature difference between the two adjacent towers are very small, and at the same time, due to the presence of salt in the medium, the temperature difference between the two adjacent towers is further reduced, and the investment in heat exchange equipment is huge; As a result, a large amount of polyols are taken away from the top of the after-effect tower, causing environmental pollution and product loss; no matter whether the after-effect vacuum tower adopts a plate tower or a packed tower, it is in the limit operating state of too high gas velocity and too small liquid volume, which is easy to Entrainment of polyols will cause environmental pollution and product loss, so it is urgent to develop an effective and energy-saving dehydration technology

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