Acetic Acid Purification Using Distillation and Membrane Dehydration
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Solution Overview
Problem
Existing methods for producing purified acetic acid from a mixed solution containing acetic acid, an organic solvent, and water face challenges due to the small boiling point difference between acetic acid and water, leading to inefficient energy use and high equipment costs, as well as incomplete separation and contamination issues.
Innovation Solution
Incorporating a membrane separation step using zeolite separation membranes into the distillation process to separate water from the purified liquid, reducing the energy load and ensuring high-quality acetic acid production by minimizing the separation of acetic acid and water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation method is used to separate acetic acid and water, then separation can be achieved, but energy consumption is high due to small boiling point difference
Solution Approach 1:
The patent divides the separation process into two distinct stages: first, distillation is used to remove most of the water and obtain purified liquid; second, membrane separation is applied to the purified liquid to remove remaining trace water. This segmentation allows each method to operate in its optimal range, reducing overall energy consumption while achieving complete separation.
Solution Approach 2:
The patent changes the operating parameters by controlling the distillation process to produce purified liquid with specific water content (0.1-5 wt%), which is then fed to the membrane separation unit. This parameter control optimizes the performance of both separation methods and minimizes energy requirements.
2Use of energy by moving object
If membrane separation is applied to separate water from acetic acid, then energy consumption is reduced, but separation efficiency decreases due to azeotropy
Solution Approach 1:
The patent performs preliminary distillation to remove the bulk of water before applying membrane separation. This preliminary action creates feed conditions (purified liquid with controlled water content) that are optimal for membrane separation, allowing the membrane process to achieve high separation efficiency with minimal energy input.
Solution Approach 2:
The patent introduces an intermediary step (distillation) between the raw acid and the membrane separation process. This intermediary process transforms the feed composition to a state where membrane separation can operate effectively, overcoming the azeotropy limitation without requiring excessive energy input.
3Stability of the object's composition
If excessive water is taken in membrane separation to prevent azeotropy, then azeotropy is avoided, but equipment cost increases due to large membrane area
Solution Approach 1:
Instead of using excessive water throughout the entire process, the patent applies partial action by using membrane separation only on the purified liquid stream after distillation. This approach prevents azeotropy in the critical final separation stage without requiring large membrane areas throughout the entire process, thus reducing equipment costs.
Solution Approach 2:
The preliminary distillation step reduces the water content to an optimal range before membrane separation, so that the membrane process does not need to handle excessive water loads. This preliminary action allows the use of smaller, more cost-effective membrane areas while still preventing azeotropy.
4Manufacturing precision
If distillation is used to completely separate water and acetic acid, then high purity acetic acid is obtained, but production cost increases due to high energy requirement
Solution Approach 1:
The patent segments the purification process into distillation for bulk water removal and membrane separation for trace water removal. This segmentation achieves high purity acetic acid production while minimizing the energy-intensive distillation step, thereby reducing overall production costs.
Solution Approach 2:
The patent replaces part of the mechanical/thermal separation system (distillation) with a membrane-based separation system. This substitution reduces energy requirements while maintaining high purity output, leading to lower production costs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves efficient separation of acetic acid and water with reduced energy consumption, resulting in high-quality purified acetic acid free from organic solvent contamination, thereby lowering production costs and improving the efficiency of acetic acid recycling in cellulose acetate production.
Implementation Method 1
separating water from the purified liquid by a separation membrane
Implementation Method 2
membrane separation step of separating water from the purified liquid by a separation membrane
Implementation Method 3
a distillation step of distilling the mixed solution and separating the mixed solution into a purified liquid rich in acetic acid and a separated liquid rich in an organic solvent
Data Source
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AI summary
Provided is a method for producing purified acetic acid from a mixed solution containing acetic acid, an organic solvent, and water in an energy-efficient manner. The method, which is for producing purified acetic acid from a mixed solution containing acetic acid, an organic solvent, and water, includes: a distillation step in which the mixed solution is distilled and separated into a purified liquid rich in acetic acid and a separated liquid rich in an organic solvent; and a membrane separation step in which the water is separated from the purified liquid by a separation membrane. The purified liquid has a water concentration of 4 wt.% or less.