Membrane Unit for Non-Aromatic Removal in Xylene Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current xylene isomerization processes for para-xylene production face challenges due to the increasing concentration of non-aromatic compounds in the recycle loop, which negatively affects para-xylene yield, process efficiency, and capacity.
Innovation Solution
A membrane unit is strategically positioned within the xylene recovery loop to selectively remove non-aromatic compounds by preferentially permeating xylenes, thereby separating a non-aromatics rich stream from other streams, allowing for continuous operation without the need for purging or dumping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a continuous purge is used to control non-aromatic compound build-up, then non-aromatic concentration is controlled, but xylenes are lost along with the non-aromatics
Solution Approach 1:
The patent extracts and removes only the harmful non-aromatic compounds from the recycle loop using a membrane separation unit, while retaining the valuable xylene components in the loop. This selective extraction eliminates the need for continuous purging that would otherwise cause xylene losses.
Solution Approach 2:
The membrane separation unit provides localized treatment of the recycle stream, creating different quality zones: the permeate stream contains removed non-aromatics while the retentate stream maintains high xylene concentration. This local quality differentiation enables selective removal without bulk purging.
2Object-affected harmful factors
If the entire recycle inventory is periodically dumped to control non-aromatics, then non-aromatic build-up is prevented, but process operation is interrupted and xylenes are lost
Solution Approach 1:
The membrane unit continuously extracts non-aromatic compounds from the recycle loop without requiring periodic interruption or complete dumping of the recycle inventory. This maintains continuous process operation while controlling non-aromatic build-up.
Solution Approach 2:
The membrane separation operates continuously to remove non-aromatics, eliminating the need for periodic batch operations or complete recycle loop dumps. This ensures uninterrupted para-xylene production while maintaining non-aromatic concentration control.
3Object-affected harmful factors
If the entire recycle inventory is periodically dumped to control non-aromatics, then non-aromatic build-up is prevented, but process operation is interrupted
Solution Approach 1:
The membrane separation unit provides continuous operation for non-aromatic removal, eliminating periodic process stoppages and dump operations. This maintains uninterrupted para-xylene production while effectively controlling non-aromatic concentration in the recycle loop.
4Productivity
If non-aromatics are removed from the recycle loop, then para-xylene yield and process efficiency improve, but additional equipment is required
Solution Approach 1:
The membrane separation unit acts as an intermediary device that selectively removes non-aromatics from the recycle loop without disrupting the core isomerization and separation processes. This modular addition improves para-xylene yield while maintaining relative simplicity of the overall system.
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 membrane unit enhances the xylene recovery loop's efficiency and capacity by continuously removing non-aromatics, reducing the need for purging, and maintaining higher yields of xylene-containing streams, while also lowering operational costs.
Implementation Method 1
the membrane unit may be configured to preferentially permeate xylenes such that it allows other molecules (e.g., non-aromatics) to permeate more slowly than xylene if it allows those other molecules to permeate at all
Data Source
AI summary
Selective removal of non-aromatic hydrocarbons from a xylene isomerization process for para-xylene production is accomplished using a membrane unit positioned within a xylene recovery loop. The membrane unit may include a one-stage or multi-stage (e.g., two-stage) membrane system and may be configured to separate a membrane unit product stream from a non-aromatics rich stream, which can be removed from the xylene recovery loop. The membrane unit may have a xylene permeance of about 60 gm/m2/hr/psi and a xylene to non-aromatic permeance ratio of about 15.