Side Draw Column Sequence for High-Purity CDON Separation
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Solution Overview
Problem
Current processes for separating cyclododecanone (CDON) from dehydrogenation mixtures containing low boilers, medium boilers, and high boilers result in impurities that can damage polyamide 12 polymers, necessitating a method to obtain high-purity CDON.
Innovation Solution
A process involving a sequence of two side draw columns connected in series, where the side stream from the primary side draw column is fed into the secondary side draw column, allowing for the withdrawal of CDON-rich fractions and separation of CDOL and high boilers, achieving a target fraction with a CDON content of at least 98% by weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation methods are used to separate CDON from dehydrogenation mixtures, then the separation process is simple, but the CDON purity is insufficient and contains impurities that damage polyamide 12 polymers
Solution Approach 1:
The separation process is divided into multiple sequential distillation columns, each performing a specific separation function. The first column removes low boilers, the second column separates CDON from medium boilers and CDOL, and the third column removes high boilers. This segmentation allows each column to be optimized for its specific separation task, achieving high CDON purity (≥98%) while maintaining manageable complexity through modular design.
Solution Approach 2:
The patent extracts and removes harmful impurities (low boilers, medium boilers, high boilers, and CDOL) from the CDON stream through sequential distillation columns. Each column specifically targets and removes certain impurity groups, progressively purifying the CDON product to meet the required purity specification for polyamide 12 production.
2Manufacturing precision
If multiple distillation columns are used to achieve high CDON purity, then the CDON purity increases to at least 98% by weight, but the device complexity and process steps increase
Solution Approach 1:
The complex separation task is segmented into three specialized distillation columns, each handling a specific range of impurities. This allows parallel optimization of each column's operating parameters (reflux ratios, feed locations, withdrawal rates) to maximize efficiency while achieving the required purity, rather than using one overly complex column with many more theoretical stages.
Solution Approach 2:
The first distillation column performs preliminary removal of low boilers before the main separation in the second column. This preliminary action reduces the burden on subsequent columns, allowing them to operate more efficiently at their optimal reflux ratios and achieving the final high purity requirement with fewer total theoretical stages across the system.
3Manufacturing precision
If conventional single-column distillation is used, then the process is simple and fast, but impurities such as CDOL, medium boilers, and high boilers remain in the CDON fraction
Solution Approach 1:
The patent segments the impurity removal into three distinct functional units: Column 1 for low boiler removal, Column 2 for main CDON/CDOL and medium boiler separation, and Column 3 for high boiler removal. Each column is designed with specific feed locations, withdrawal points, and reflux ratios optimized for its particular separation task, achieving comprehensive impurity removal while keeping each individual column relatively simple.
Solution Approach 2:
The patent systematically extracts different groups of impurities in sequence through three distillation columns. Column 1 extracts low boilers (boiling point < CDON), Column 2 extracts medium boilers and CDOL (boiling point > CDON), and Column 3 extracts high boilers (boiling point >> CDOL). This sequential extraction ensures complete removal of all impurity groups that would damage polyamide 12 polymers.
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 process effectively separates high-purity CDON, reducing the presence of CDOL, medium boilers, and high boilers, thereby minimizing damage to polyamide 12 production and enhancing the quality of laurolactam production.
Implementation Method 1
A process involving a sequence of two side draw columns connected in series, where the side stream from the primary side draw column is fed into the secondary side draw column, allowing for the withdrawal of CDON-rich fractions
Data Source
AI summary
Removing a cyclododecanone-rich fraction from a dehydrogenation mixture comprising low boilers, cyclododecanone, medium boilers, cyclododecanol and high boilers, comprises: (a) feeding the dehydrogenation mixture to a preliminary separator column; (b) distillatively removing the low boilers from the dehydrogenation mixture to obtain a first mixture comprising cyclododecanone, medium boilers, cyclododecanol and high boilers; (c) feeding the first mixture into a primary side draw column (7); and (d) drawing off a first cyclododecanone-rich fraction from the top of the primary side draw column. Removing a cyclododecanone-rich fraction from a dehydrogenation mixture comprising low boilers, cyclododecanone, medium boilers, cyclododecanol and high boilers, comprises: (a) feeding the dehydrogenation mixture to a preliminary separator column; (b) distillatively removing the low boilers from the dehydrogenation mixture to obtain a first mixture comprising cyclododecanone, medium boilers, cyclododecanol and high boilers; (c) feeding the first mixture into a primary side draw column (7); (d) drawing off a first cyclododecanone-rich fraction from the top of the primary side draw column; (e) drawing off a first fraction comprising cyclododecanol and high boilers from the bottom of the primary side draw column; (f) drawing off a second mixture comprising cyclododecanone, cyclododecanol and medium boilers from the side draw of the primary side draw column; (g) feeding the second mixture into a secondary side draw column; (h) drawing off a second cyclododecanone-rich fraction from the top of the secondary side draw column; (i) drawing off a second fraction comprising cyclododecanol and high boilers from the bottom of the secondary side draw column; (j) drawing off a third mixture comprising cyclododecanone, cyclododecanol and medium boilers from the side draw of the secondary side draw column; and (k) combining the first cyclododecanone-rich fraction and the second cyclododecanone-rich fraction to obtain the cyclododecanone-rich target fraction.