Simulated Moving Bed Adsorptive Separation with Crystallizer
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Solution Overview
Problem
Conventional SMB adsorptive separation processes for p-xylene from aromatic hydrocarbon mixtures face limitations in productivity, as they require large amounts of solvent, struggle with separating components with similar adsorption properties, and are not suitable for massive or continuous separation.
Innovation Solution
The process involves a simulated moving bed adsorptive separation using a device with multiple adsorption chambers connected in parallel, where extracts are further separated in a crystallizer, enhancing productivity by simulating counterflow through rotary valve operation and connecting adsorption chambers to an extract column and crystallizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional batch chromatography is used for separation, then high purity separation can be achieved, but it requires a large amount of solvent and is not suitable for continuous separation
Solution Approach 1:
The continuous chromatography system is divided into multiple discrete adsorption columns (typically 4-12 columns) arranged in a circuit, with each column performing a specific function (adsorption, desorption, transfer, etc.) at different stages of the cyclic process. This segmentation enables continuous operation while maintaining high separation purity and reducing solvent consumption compared to batch methods.
Solution Approach 2:
The system operates through periodic switching of flow directions and column functions using valve assemblies. Each column cycles through different operational modes (adsorption, desorption, transfer) in a repeating sequence, enabling continuous separation with improved solvent efficiency and productivity compared to conventional batch chromatography.
2Manufacturing precision
If conventional batch chromatography is used, then separation with high purity can be achieved, but separation of components with similar adsorption properties is hardly achieved
Solution Approach 1:
Different sections of the chromatographic system (different columns or zones within columns) are optimized for specific separation tasks. The stationary phase composition, particle size, and column dimensions can be varied locally to enhance selectivity for components with similar adsorption properties, improving the system's ability to resolve difficult separations.
3Productivity
If conventional batch chromatography is used, then separation can be performed, but it is not appropriately used for separation in massive amount and continuous separation
Solution Approach 1:
The system maintains continuous operation by having multiple columns working in different phases of the separation cycle simultaneously. While one column is in desorption mode, another is in adsorption mode, ensuring uninterrupted processing. This continuous operation dramatically increases productivity and processing capacity compared to batch methods, enabling massive amount separation.
4Productivity
If true moving bed (TMB) process is used, then counter current flow efficiency is achieved, but friction and leakage of filling material occur and work in normal state is hardly achieved
Solution Approach 1:
Instead of physically moving the stationary phase as in TMB, the invention creates a simulated moving bed effect by periodically switching the roles of fixed columns through valve manipulation. This copying of the TMB concept using stationary columns eliminates friction and leakage problems while maintaining the counter-current flow efficiency and high productivity benefits.
5Reliability
If simulated moving bed (SMB) process is used, then operational stability is improved, but productivity is limited compared to conventional processes
Solution Approach 1:
The invention merges multiple SMB columns into a single integrated continuous system with interconnected flow paths and coordinated valve switching. This combination of multiple columns operating in parallel and series configurations increases the overall processing capacity and production rate while maintaining the operational stability benefits of SMB technology.
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 significantly increases production rate by up to 35% and improves purity, addressing the limitations of conventional SMB processes by efficiently separating p-xylene through additional crystallization steps.
Implementation Method 1
a component which has stronger adsorption tendency to the stationery phase comes out of the column along with the flow of the stationery phase
Implementation Method 2
a crystallizer which separate the desired component from the feed for a crystallizer
Data Source
AI summary
Provided is a process for adsorptive separation of p-xylene from an aromatic hydrocarbon mixture comprising other isomers of xylene, and a device used therein. More specifically, the present invention provides a separation process employing simulated moving bed (SMB) adsorptive chromatography, characterized by subjecting the extracts eluted from a plurality of adsorption chambers arranged in parallel, to a crystallizer for additional separation, thereby improving productivity, and a device used therein.