Side-Cut Distillation Column for NMP Purification
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Solution Overview
Problem
The existing on-site distillation apparatus for purifying NMP from lithium ion secondary battery production struggles to maintain high recovery rates and stability in the face of varying water concentrations and throughput.
Innovation Solution
A single tower-type side-cut distillation column is used, where light-boiling components are removed at the top and high-boiling components at the bottom, with high-purity NMP withdrawn as a side-cut vapor and liquefied, and a flow control mechanism regulates the liquid level to ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single tower-type distillation column is used to reduce apparatus size, then device complexity is reduced, but manufacturing precision and purification effectiveness may deteriorate
Solution Approach 1:
The single distillation column is segmented into multiple functional zones: a top portion for removing light-boiling components (water), a bottom portion for removing high-boiling components, and a mid-stage portion for withdrawing high-purity NMP as side-cut vapor. This segmentation allows the simple single-tower structure to achieve multi-stage purification effectiveness comparable to complex multi-column systems.
Solution Approach 2:
Different portions of the distillation column are assigned different local functions with optimized characteristics: the top portion handles water removal, the bottom portion handles high-boiling component removal, and the mid-stage portion optimizes for high-purity NMP withdrawal. This local optimization enables the simple structure to achieve high purification precision (purity of not less than 99.9% by weight).
2Adaptability or versatility
If the distillation column operates under varying water content and throughput conditions, then adaptability is improved, but operational stability deteriorates
Solution Approach 1:
The distillation apparatus employs dynamic flow control mechanisms that automatically adjust operating parameters based on real-time conditions. The flow control means regulates the amount of high-purity NMP withdrawn from the condenser to the product tank based on liquid level in the bottom portion, enabling the system to adapt to variations in water content and throughput while maintaining stable operation and preventing liquid level fluctuations that could compromise reliability.
Solution Approach 2:
The system incorporates feedback control through flow control means that monitors liquid level in the bottom portion of the distillation column and adjusts the withdrawal rate of condensed NMP accordingly. This feedback mechanism ensures that operational stability is maintained even when raw material concentration or throughput varies, as the system automatically compensates to keep liquid levels within the predetermined range.
3Manufacturing precision
If high-purity NMP is withdrawn as side-cut liquid from mid-stage portion, then purification is achieved, but recovery rate is limited to about 85%
Solution Approach 1:
The invention utilizes phase transition by withdrawing high-purity NMP as vapor from the mid-stage portion of the distillation column and then condensing it in a condenser. This vapor-liquid phase transition approach enables higher recovery rates (over 90%) compared to liquid withdrawal methods, as the vapor phase allows for more complete separation and condensation of NMP from impurities.
Solution Approach 2:
The system changes the physical state parameter of NMP from liquid to vapor during withdrawal and separation, then transitions it back to liquid in the condenser. This parameter change enables more efficient separation and higher recovery rates, as vapor withdrawal from the mid-stage portion captures NMP before it mixes with liquid impurities in the bottom portion, and subsequent condensation achieves complete recovery.
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 enhances the recovery rate of high-purity NMP to over 90% while maintaining stable operation despite variations in throughput or water content, ensuring safe and simple on-site purification.
Implementation Method 1
a distillation column in which water comprising light-boiling components is removed from a raw NMP in a top portion thereof to separate a high-concentration NMP from the raw NMP
Implementation Method 2
water comprising light-boiling components is removed from a raw NMP in a top portion thereof
Implementation Method 3
a cooling condenser, and a pump, in which high-boiling components are further removed from the high-concentration NMP in a bottom portion of the distillation column
Implementation Method 4
high-purity NMP in a vaporized state which comprises a less amount of impurities is withdrawn as a side-cut vapor from a mid-stage portion of the distillation column and then liquefied by a condenser
Data Source
AI summary
A distillation apparatus is capable of regenerating spent NMP from an on-site process for lithium ion battery electrodes. The distillation apparatus has a raw material tank, a side-cut distillation column, and a product tank. The distillation column has a top portion where a liquid to be treated is separated into a high-concentration NMP and water containing light-boiling components, a bottom portion where refluxed liquid in the distillation column is further distilled to separate the refluxed liquid into a high-purity NMP and the high-concentration NMP containing high-boiling components, and a mid-stage portion from which the high-purity NMP is withdrawn as side-cut vapor. The distillation column has, at a rear stage, a condenser for condensing the high-purity NMP withdrawn as the side-cut vapor, and a flow controller for regulating an amount of a liquid of the high-purity NMP withdrawn from the condenser to the product tank.