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A separation and purification method for energy-saving dehydration and impurity removal of ethylene glycol aqueous solution

An ethylene glycol, aqueous solution technology, applied in the separation/purification of hydroxyl compounds, chemical instruments and methods, organic chemistry, etc. The effect of saving energy consumption, improving safety and improving input-output ratio

Active Publication Date: 2020-09-01
SICHUAN TECHAIRS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, the main defect of the steam permeation membrane separation method is similar to that of the pervaporation method, the flux is small, and it is difficult to achieve the high concentration index of the ethylene glycol aqueous solution; The new separation method has the advantages of large separation coefficient and relatively large flux, but it is still unable to economically concentrate the ethylene glycol aqueous solution from 15-25% concentration to 60-80%, and it is even more difficult to complete the ethylene glycol aqueous solution. Deep dehydration and impurity removal
When the ethylene glycol aqueous solution is initially concentrated to 50~60%, the three membrane separation concentration methods cannot compare with the first-effect and second-effect evaporation in terms of energy efficiency ratio and input-output ratio.
Similarly, the membrane separation method is also difficult to achieve the deep dehydration of ethylene glycol with the same energy efficiency ratio as the traditional vacuum drying method
[0004] Vacuum drying and adsorption dehydration methods are only suitable for the deep dehydration of ethylene glycol, and cannot economically undertake the concentration of ethylene glycol aqueous solution

Method used

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  • A separation and purification method for energy-saving dehydration and impurity removal of ethylene glycol aqueous solution
  • A separation and purification method for energy-saving dehydration and impurity removal of ethylene glycol aqueous solution

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Embodiment 1

[0038] like figure 1 and figure 2 Shown, a kind of separation and purification method of ethylene glycol aqueous solution dehydration impurity removal, comprises following operation:

[0039] (1) Multi-effect evaporation and concentration process, the ethylene glycol aqueous solution with a concentration of about 25% (mass ratio, the same below) from the ethylene oxide hydration reactor, the temperature is 100°C, and enters the co-current second effect after pressure relief The first-effect evaporator of the evaporation system, evaporates and concentrates to 40%, and then sends it to the second-effect evaporator, evaporates and concentrates to about 60%, and realizes initial concentration. Among them, the condensate of the second-effect secondary steam is introduced at the top of the second-effect evaporator as the reflux liquid, so that it is in countercurrent contact with the rising secondary steam in the evaporator, and the ethylene glycol component in the steam is recove...

Embodiment 2

[0050] On the basis of the separation and purification method for energy-saving dehydration and impurity removal of a kind of ethylene glycol aqueous solution described in Example 1, it is further optimized. In the pervaporation re-concentration process, a vacuum pump is used to obtain a certain vacuum on the permeation side of the pervaporation membrane. The method maintains the partial pressure difference between water and trace impurity components on both sides of the pervaporation membrane, allowing water and trace impurity components to pass through continuously, while the non-permeable ethylene glycol components are further concentrated to 88~90 %, as the feed liquid of the next process-liquid phase adsorption process, it is passed into the liquid phase adsorption tower for liquid phase adsorption, and the ethylene glycol product with a purity of 99.9~99.99% or more is obtained from the bottom of the tower. This can reduce the load of the liquid phase adsorption process. ...

Embodiment 3

[0052] On the basis of the separation and purification method of dehydration and impurity removal of a kind of ethylene glycol aqueous solution described in Example 1, it is further optimized, and the described pervaporation reconcentration process comes from 60% of the two-effect evaporator in the multi-effect evaporation concentration process. % ethylene glycol aqueous solution at a temperature of 100°C, and enters the pervaporation re-concentration process consisting of two-stage pervaporation membranes and components under normal pressure, wherein the ethylene glycol re-concentration solution that has not passed through the first-stage pervaporation membrane is used as In the two-stage pervaporation membrane system, the concentration of ethylene glycol concentrate that has not passed through the two-stage pervaporation membrane reaches 88~90%; while the permeate (condensed water and trace impurities) of the primary and secondary pervaporation membranes ) mixed with the cond...

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Abstract

The invention discloses a separation and purification method for energy-saving dehydration and impurity removal of an ethylene glycol aqueous solution. The ethylene glycol aqueous solution enters multi-effect evaporation and concentration, osmotic vaporization and re-concentration, liquid-phase adsorption, extraction and desorption, and extracting agent regeneration processes sequentially, and anethylene glycol product with the purity being more than or equal to 99.9-99.99% is obtained from the bottom of an absorption tower in the liquid-phase adsorption process; the operation temperature inthe whole dehydration and impurity removal processes is the same as the feed temperature; ethylene glycol contained in a condensate is further recovered in the multi-effect evaporation, osmotic vaporization and extracting agent regeneration processes, and the yield of the ethylene glycol reaches 96-99%. The separation and purification method disclosed by the invention has the benefits that by utilizing the gas-liquid equilibrium and energy efficiency ratio of the glycol aqueous solution at different concentrations, the energy economy utilization ratio in the dehydration and the impurity removal reaches 80-100%; compared with that of a traditional multi-effect evaporation-vacuum drying and dehydration process, the energy consumption is reduced by about 1-2 times. A deep dehydration and impurity removal process for an ethylene glycol concentrate by liquid-phase adsorption and (super) critical extraction and desorption is also introduced, can be matched with an ethylene glycol and poly-glycol separation refining system and is high in integration degree.

Description

technical field [0001] The invention belongs to the technical field of chemical industry separation and purification, and more specifically relates to a separation and purification method for energy-saving dehydration and impurity removal of ethylene glycol aqueous solution. Background technique [0002] Ethylene glycol is the main chemical raw material for the manufacture of polyester fibers and antifreeze agents, and can also be used to produce some special chemical products, such as alkyd resins, fluids for hydraulic systems, plasticizers, glyoxal, etc. The production method of ethylene glycol. At present, most of the ethylene glycol plants in China are mainly ethylene oxide (EO) pressurized hydration method, which combines ethylene oxide with water at a mass ratio of 20~25:1. Under the following conditions, an aqueous solution of ethylene glycol with an ethylene glycol content of about 15-25% (mass ratio, the same as below) is generated, and then undergoes multiple-effec...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C29/74C07C29/76C07C29/78C07C29/86C07C31/20
CPCC07C29/74C07C29/76C07C29/78C07C29/86C07C31/202
Inventor 陈运蔡跃明钟雨明刘开莉
Owner SICHUAN TECHAIRS
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