Isopropyl Alcohol Purification Using Molecular Sieves and Divided Wall Column
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Solution Overview
Problem
The challenge in producing high-purity isopropyl alcohol (IPA) lies in the difficulty of removing water from IPA-water azeotropes, which hinders efficient purification due to their similar boiling points, leading to residual water content that affects the efficiency of subsequent distillation processes.
Innovation Solution
A method involving a dehydration process using molecular sieves to reduce water content in the feed to 300 ppm or less, followed by a purification process in a Divided Wall Column (DWC) to enhance the efficiency of IPA production, where the DWC separates low, middle, and high-boiling components effectively, and regeneration of molecular sieves is done to maintain dehydration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation is used to separate IPA from water, then the process is simple, but the separation efficiency is poor due to azeotrope formation
Solution Approach 1:
The purification process is segmented into two distinct stages: (1) dehydration stage using molecular sieve columns to remove water and form an IPA-rich stream, and (2) distillation stage to further purify the IPA. This segmentation allows each stage to be optimized for its specific function, overcoming the azeotrope limitation by first reducing water content below the azeotropic composition.
Solution Approach 2:
The molecular sieve dehydration is performed as a preliminary action before distillation. By pre-removing water to achieve water content below the azeotropic point (creating an IPA-rich stream), the subsequent distillation process can efficiently separate IPA without being hindered by azeotrope formation.
2Manufacturing precision
If molecular sieve dehydration is used to remove water, then water content is reduced effectively, but energy consumption increases due to additional processing steps
Solution Approach 1:
The molecular sieves are regenerated in-situ within the same columns by heating with steam or hot gas to desorb accumulated water, then cooling to restore dehydration capacity. This recovery process eliminates the need for separate regeneration equipment and allows continuous operation with two columns alternating between dehydration and regeneration modes.
Solution Approach 2:
The dehydration and molecular sieve regeneration functions are merged into the same column structure. The columns serve dual purposes: dehydration during service mode and regeneration during regeneration mode, reducing overall system complexity and energy consumption compared to separate units.
3Manufacturing precision
If molecular sieve columns are used for dehydration, then water removal efficiency is improved, but the frequency of regeneration increases leading to operational interruptions
Solution Approach 1:
The system uses two molecular sieve columns that operate in alternating cycles. While one column is performing dehydration, the other is being regenerated. This segmentation of time and function ensures continuous dehydration capability without operational interruptions.
Solution Approach 2:
The columns operate in periodic cycles alternating between dehydration mode and regeneration mode. This periodic action ensures that at any given time, one column is actively dehydrating while the other is being prepared, maintaining continuous operational capacity.
Data Source
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AI summary
The present application relates to an apparatus for purifying isopropyl alcohol. The present application enables isopropyl alcohol to be obtained in a high purity from a feed comprising water and isopropyl alcohol with a minimum amount of energy consumption.