Raman Spectroscopy for Para-Xylene Separation Control

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Solution Overview

Problem

Current methods for determining the compositional profile of para-xylene in simulated moving bed separation processes are time-consuming, labor-intensive, and disrupt plant operations, providing limited real-time data for precise control and optimization.

Innovation Solution

Implementing a Raman system with a probe and spectrophotometer for inline sampling of intermediate streams between adsorbent sub-beds, using laser light to generate spectra that assess concentrations of para-xylene and other components, allowing for continuous, automated generation of pump-around profiles without process disruption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If on-line gas chromatography analysis is used to determine compositional profile, then real-time data is provided, but analysis time is too long (10 minutes per analysis) compared to valve step time (60 seconds)

Engineering Contradiction:

Improvecompositional profile accuracyVSAvoidanalysis time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical gas chromatography system with an optical Raman spectroscopy system. The Raman system uses laser light to excite molecular vibrations and detects scattered light to identify and quantify components, providing rapid compositional analysis without the time-consuming mechanical separation and detection processes of gas chromatography.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from gas chromatography retention times and detector responses to Raman spectral frequencies and intensities. This parameter change enables much faster analysis since Raman spectroscopy provides instantaneous spectral data compared to the sequential elution process of gas chromatography.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If manual sampling and off-line laboratory analysis are used, then detailed compositional data is obtained, but operator labor and plant disruption increase

Engineering Contradiction:

Improvecompositional profile accuracyVSAvoidoperator intervention

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The Raman system is installed inline in the process stream and performs autonomous compositional analysis without requiring operator sampling or intervention. The system continuously monitors the process automatically, eliminating manual labor while maintaining measurement accuracy.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent introduces an intermediary Raman spectroscopy system that bridges the gap between process control needs and compositional analysis requirements. This intermediary system provides detailed compositional data through optical measurement without requiring physical sampling or laboratory analysis.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of time

If only selected valve positions are sampled for analysis, then analysis time is reduced, but information about separation process performance is limited

Engineering Contradiction:

Improveanalysis timeVSAvoidseparation process data

Core Design Contradiction:

Loss of timeVSLoss of information

Solution Approach 1:

The Raman system provides continuous compositional monitoring at all valve positions throughout the cycle, rather than discrete sampling at selected positions. This continuous measurement approach captures complete separation process information while maintaining rapid analysis speed.

Inventive Principle:

Principle #20Continuity of useful action

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

Enables rapid and frequent compositional analysis with minimal operator intervention, providing accurate, ongoing data for improved process control and optimization with reduced maintenance.

Implementation Method 1

The intermediate stream is irradiated with laser light that is directed from a probe of a Raman system positioned for inline sampling of the intermediate stream. Scattered light from the irradiated intermediate stream is collected with the probe. A spectrum of the scattered light is generated with the Raman system to assess concentrations of one or more of para-xylene and other components in the intermediate stream.

Methodology Applied

Scientific EffectRaman scattering: Scattering

Data Source

PatentUS8884092B2Simulated moving bed systems for separation of para-xylene and processes for determining pump-around profiles of the simulated moving bed systems

Publication Date: 2014.11.11 UOP LLC

AI summary

Embodiments of simulated moving bed systems for separating a preferentially adsorbed component from a feed stream and processes for determining a pump-around profile of the simulated moving bed systems are provided. The process comprises the steps of rotating a rotary valve to a first valve position to direct the feed stream to a first adsorbent sub-bed. An intermediate stream between two adsorbent sub-beds in direct fluid communication with each other is irradiated with laser light that is directed from a probe of a Raman system positioned for inline sampling of the intermediate stream. Scattered light from the irradiated intermediate stream is collected with the probe. A spectrum of the scattered light is generated with the Raman system to determine concentrations of the preferentially adsorbed component and one or more other components in the intermediate stream.