PowerFeed Xylene Separation in Simulated Moving Bed

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Solution Overview

Problem

Current simulated moving bed adsorption processes for separating paraxylene from mixtures of C8 aromatics are inefficient and require a large number of adsorbent beds, conduits, and connection devices, limiting process efficiency and purity of product streams.

Innovation Solution

Implementing a PowerFeed process in a commercial simulated moving bed apparatus with reduced adsorbent beds, where the flow rate of streams is varied during step time intervals in two separate adsorption zones to achieve additional separation of paraxylene and other C8 aromatics or non-aromatic hydrocarbons, allowing for a dual separation in a reduced bed configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a large number of adsorbent beds are used in simulated moving bed adsorption, then separation efficiency and product stream purity are improved, but device complexity and the number of conduits and connection devices increase

Engineering Contradiction:

Improveproduct stream purityVSAvoidnumber of conduits and connection devices

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The adsorption apparatus is divided into two distinct adsorption zones with different functions: the first zone separates paraxylene from C8 aromatics while the second zone separates ethylbenzene from the raffinate. This segmentation allows each zone to be optimized for its specific separation task, achieving high purity products with fewer total beds than a single-zone system would require.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a temporal dimension by implementing PowerFeed flow rate modulation during step time intervals. By varying flow rates dynamically during the adsorption cycle, the system achieves enhanced separation efficiency without requiring additional spatial components (more beds or conduits), thus resolving the contradiction between purity and device complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If the number of adsorbent beds is reduced, then device complexity is decreased, but separation efficiency and productivity are reduced

Engineering Contradiction:

Improvenumber of bedsVSAvoidthroughput

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent applies PowerFeed operation by dynamically modulating flow rates during step time intervals rather than maintaining constant flow. This dynamic adjustment optimizes mass transfer and adsorption capacity utilization in real-time, allowing the reduced-bed system to maintain high productivity and separation efficiency despite having fewer adsorbent beds.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters by implementing variable flow rates during different phases of the adsorption cycle. By adjusting flow rates as a function of time within each step interval, the system maximizes the utilization of available adsorbent capacity, compensating for the reduced number of beds and maintaining high throughput.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If conventional simulated moving bed adsorption is used, then process simplicity is maintained, but additional separation of metaxylene, orthoxylene, ethylbenzene, or non-aromatic is not achieved

Engineering Contradiction:

Improveadditional separation capabilityVSAvoidprocess configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dual-zone system provides multi-functionality by simultaneously enabling paraxylene separation from C8 aromatics and ethylbenzene separation from raffinate within the same apparatus. The system can handle multiple separation tasks using the same adsorbent beds and fluid circulation infrastructure, enhancing versatility without proportionally increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 PowerFeed process enhances the separation efficiency and purity of product streams while reducing the number of beds and conduits needed, maintaining or improving throughput and adsorbent efficiency compared to conventional systems.

Implementation Method 1

adsorption, using an adsorbent solid which preferentially adsorbs paraxylene over metaxylene and orthoxylene in a simulated moving bed apparatus

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

modulation of flow during the step time has been found to enhance separation in certain instances involving simulated moving bed separation

Methodology Applied

Scientific EffectFluid flow modulation:

Data Source

PatentUS10392324B2Xylene separation process

Publication Date: 2019.08.27 GEORGIA TECH RES CORP

AI summary

A process to separate paraxylene from a mixture of paraxylene, metaxylene, orthoxylene, and ethylbenzene in a commercial simulated moving bed apparatus in a reduced number of beds is provided, allowing an additional separation to be conducted in the remaining beds. This additional separation may separate another xylene isomer, ethylbenzene, or a non-aromatic C8+ hydrocarbon from the raffinate stream produced by the first separation. A PowerFeed process is used to recover paraxylene in a first adsorption zone containing 8-16 beds of a conventional 24-bed simulated moving bed adsorption apparatus, and then a second separation may be conducted in a second adsorption zone containing the remaining beds.