Dual Extract Flush for Simulated Moving Bed Xylene Separation
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Solution Overview
Problem
Current xylene extraction processes using simulated moving beds face inefficiencies due to coupled line flush settings, residual feed material introduction, inefficient desorbent usage, and contamination issues, which impact product purity and adsorptive capacity.
Innovation Solution
Decoupling line flush in and line flush out processes, using extract material for both flushes, and optimizing bedline flushing volumes to minimize contamination and desorbent usage, with a second flush ensuring cleanliness and relocating over-flushed components to maintain adsorptive capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If line flush in and line flush out are coupled together, then the process is simpler to operate, but the optimal settings for each flush cannot be independently optimized
Solution Approach 1:
The patent divides the coupled line flush in and line flush out processes into two independent flush operations. Each flush can now be optimized separately with independent control parameters, allowing line flush in to be optimized at >100% and line flush out at approximately 100%, thereby resolving the contradiction between operational simplicity and optimization precision.
2Manufacturing precision
If the first flush uses a volume greater than bedline volume, then residual feed material is flushed out, but desorbent is wasted and sent to the extract column requiring additional heat separation
Solution Approach 1:
The patent introduces a preliminary second flush operation that occurs before material is sent to the extract column. This second flush cleans the bedline of desorbent and residual contaminants, preventing them from entering the extract column. The preliminary action eliminates the need for additional heat separation duty, resolving the energy waste problem while maintaining purity through the optimized first flush.
3Productivity
If feed remains in the feed bedline after first flush, then it is added to chambers two full beds after feed introduction, but this introduces inefficiency in feed separation
Solution Approach 1:
The patent extracts residual feed material from the bedline through the optimized first flush operation with independent control. By setting the first flush to >100% of bedline volume, the system removes feed material before it can be reintroduced to downstream chambers, eliminating the separation inefficiency while maintaining high productivity through optimized flush timing and volume.
4Productivity
If residual contaminants remain in the bedline after first flush, then they are sent to the bed directly below extract, but only one bed of separation is available to remove these contaminants
Solution Approach 1:
The patent introduces a preliminary second flush operation that removes residual contaminants from the bedline before material is sent to the extract column. This preliminary cleaning action ensures that when material does enter the extract column, the contaminant load is minimized, allowing the single bed of separation to effectively maintain product purity without compromising productivity.
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 product purity, reduces desorbent consumption, and maintains adsorptive capacity by optimizing each flush independently and ensuring residual contaminants are removed effectively, thereby improving the overall efficiency of xylene extraction processes.
Implementation Method 1
passing a feed and desorbent into a unit wherein the unit comprises a desorption zone, a purification zone, and an adsorption zone
Data Source
AI summary
The present invention relates to dual extract flush for feeds for xylene extraction processes. More specifically, the present invention relates to dual extract flush for feeds for simulated moving bed extraction processes. It decouples line flush in and line flush out, providing a means for optimizing each flush independently. This scheme will allow for minimizing each bedline and flushing each according to its own bedline volume, which will minimize any additional non-ideal compositions added to the chambers or downstream fractionation.