Styrene Solvent Purification via Liquid-Liquid Extraction
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Solution Overview
Problem
Current methods for purifying solvents in extractive distillation processes, such as those used for styrene separation, face challenges in effectively removing styrene polymers, which can lead to solvent degradation and operational inefficiencies, requiring additional steps and equipment for purification and recovery.
Innovation Solution
A method that introduces styrene as a purifying agent in the solvent purification zone, combined with liquid-liquid extraction and steam stripping, to efficiently remove styrene polymers, simplify operation steps, and extend the stable operation time of the device, without the need for separate purifying agent recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional steam stripping regeneration method is used, then high boiling point polymers can be removed, but low molecular polymers with boiling points close to the solvent cannot be effectively removed
Solution Approach 1:
The patent changes the purification approach from thermal-based (steam stripping) to mass transfer-based (liquid-liquid extraction). By introducing a purifying agent that forms a separate phase, the system exploits differences in solubility and phase distribution to remove polymers of various molecular weights, overcoming the limitation of steam stripping which relies on boiling point differences.
Solution Approach 2:
The patent introduces a purifying agent as an intermediary substance that facilitates polymer removal. This purifying agent forms a separate phase with the polymer-rich mixture, enabling selective extraction and separation of polymers from the solvent system without requiring high temperature steam stripping.
2Reliability
If purifying agent recovery column is added to separate purifying agent and polymer, then purification effect is improved, but operation steps and separation equipment are increased
Solution Approach 1:
The patent merges the purification function with the existing extractive distillation column by introducing the purifying agent into the solvent system already present in the column. This integration allows polymer removal without requiring separate dedicated equipment for purifying agent recovery, as the same column handles both extraction and purification functions.
Solution Approach 2:
The patent makes the extractive distillation column multi-functional by enabling it to perform both styrene separation and polymer removal simultaneously through the addition of the purifying agent. This universal approach eliminates the need for separate specialized equipment for each function.
3Reliability
If more purifying agent is used to ensure complete polymer removal, then solvent performance is maintained, but energy consumption and operational cost increase
Solution Approach 1:
The patent optimizes the amount of purifying agent by changing the approach from bulk thermal treatment to targeted mass transfer. By controlling the phase distribution and solubility parameters, the system achieves effective polymer removal with minimal purifying agent consumption, reducing energy requirements compared to conventional methods that require large amounts of steam or multiple processing stages.
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 effectively removes styrene polymers, reduces energy consumption, and maintains solvent performance, thereby ensuring long-term operation of the device with fewer operational steps and equipment requirements.
Implementation Method 1
a part of the rich solvent is separated and sent to a solvent purification zone where water is introduced; after a liquid-liquid extraction
Implementation Method 2
a styrene-containing feedstock is introduced into an extractive distillation column from the middle, and a solvent for an extractive distillation is introduced into the extractive distillation column from an upper part; after an extractive distillation
Data Source
AI summary
A method for purification of a styrene-containing feedstock includes steps of introducing the styrene-containing feedstock into the middle of an extractive distillation column, and a solvent for the extractive distillation into the upper part of the column; discharging a raffinate oil from the top of the column, and a rich solvent rich in styrene from the bottom of the column. The rich solvent is then introduced into the middle of the solvent recovery column for vacuum distillation to obtain a crude styrene from the top of the solvent recovery column, and a lean solvent is discharged from the bottom of the solvent recovery column and recycled to the upper part of the extractive distillation column. A portion of the rich solvent is sent to a solvent purification zone for a liquid-liquid extraction using water to obtain a mixture of a styrene polymer and styrene.