Acetone Purification via Pressure-Shifted Distillation
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Solution Overview
Problem
The separation of acetone from methanol in the production of bisphenol A is challenging due to the formation of an azeotrope, leading to catalyst deactivation and significant losses of acetone in the overhead stream during purification, especially at low relative volatility concentrations.
Innovation Solution
A method involving a separation column operating at pressures greater than or equal to 1 bar, where at least 80% of the overhead stream is reconstituted and returned to the column, reducing acetone losses by increasing methanol concentration and enhancing mass transfer, while purging a smaller percentage of the overhead stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional distillation methods are used to separate acetone from methanol, then separation can be achieved, but significant losses of acetone occur in the overhead stream and the process becomes complex and expensive
Solution Approach 1:
The patent changes the pressure parameter of the distillation column to operate at pressures above the azeotropic point (greater than 0.2 MPa), which fundamentally alters the vapor-liquid equilibrium relationship between acetone and methanol. This parameter change eliminates the need for complex extractive distillation or pressure-swing methods, achieving effective separation with a single column and significantly reducing acetone losses in the overhead stream.
2Manufacturing precision
If the concentration of methanol is reduced from 250 ppm to below 30 ppm, then purification precision is improved, but a heavy distillation column is required
Solution Approach 1:
By operating the distillation column at elevated pressures (above 0.2 MPa), the patent changes the relative volatility between acetone and methanol, enabling high purification precision (below 30 ppm methanol) without requiring an excessively complex or large-scale distillation column. The pressure parameter change optimizes the separation efficiency throughout the concentration range.
3Use of energy by moving object
If separation is performed at lower pressures, then energy consumption is reduced, but the relative volatility between acetone and methanol decreases making separation difficult
Solution Approach 1:
The patent identifies and exploits the non-monotonic relationship between pressure and relative volatility for the acetone-methanol system. By operating at specific elevated pressures (above 0.2 MPa), the method achieves enhanced relative volatility and separation efficiency while maintaining reasonable energy consumption, avoiding both the low efficiency of atmospheric pressure distillation and the high energy cost of vacuum distillation.
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
This approach achieves a purified acetone stream with less than 50 ppm methanol, significantly reducing acetone losses and improving separation efficiency, particularly at high acetone mass fractions, and allows for further recovery of acetone in subsequent processing steps.
Implementation Method 1
separating the feed stream in the separation column that is operating at a pressure greater than or equal to 1 bar into an overhead stream and a purified acetone stream
Data Source
AI summary
In an embodiment a method of purifying acetone, comprises directing a feed stream comprising greater than or equal to 97 wt % of acetone and 100 to 1,000 ppm of methanol to a separation column, both based on a total weight of the feed stream; separating the feed stream in the separation column that is operating at a pressure greater than or equal to 1 bar into an overhead stream and a purified acetone stream comprising less than or equal to 50 ppm of methanol based on a total weight of the purified acetone stream; and directing at least 80 wt % of the overhead stream into the separation column as a reconstituted stream and purging 1 to 20 wt % of the overhead stream as a purge stream.