Online Ethylene Oxide Impurity Measurement System
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Solution Overview
Problem
Current methods for measuring impurities in high-purity liquid ethylene oxide product streams are inefficient due to the need for off-line sampling and analysis, which results in significant lag times and difficulties in adjusting process variables in real-time, leading to potential production of off-spec products and financial losses.
Innovation Solution
An automated on-line method and system for detecting impurities in liquid ethylene oxide streams using a gas chromatograph analyzer system with a sample conditioning system that minimizes the risk of polymerization and allows for real-time analysis of impurities such as aldehydes, water, and carbon dioxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If off-line sampling and lab analysis methods are used to measure impurity concentrations, then measurement accuracy can be achieved through multiple lab methods (GC, LC, titration), but significant lag time occurs making real-time process adjustment impossible
Solution Approach 1:
The patent replaces manual off-line sampling and lab-based mechanical analysis systems with an automated on-line gas chromatograph system. The GC analyzer continuously measures impurity concentrations directly in the process stream, eliminating the time delay associated with manual sampling, sample transport, and laboratory analysis while maintaining measurement accuracy through automated detection methods.
Solution Approach 2:
The system enables self-service by implementing automated sampling and analysis capabilities within the process line itself. The on-line GC system automatically draws samples, analyzes them, and provides results without requiring external laboratory intervention, thereby eliminating the lag time between sampling and result availability while maintaining precise measurement capabilities.
2Reliability
If aggressive process adjustments are made to prevent off-spec product during lag time, then product quality can be protected, but production efficiency and profitability decrease
Solution Approach 1:
The patent implements real-time feedback by continuously monitoring impurity concentrations through the on-line GC system and immediately providing data to the control system. This enables dynamic adjustment of process variables based on actual measured values, allowing the process to maintain product quality specifications while operating at optimal efficiency without requiring conservative or aggressive default adjustments.
Solution Approach 2:
The system ensures continuous useful action by providing uninterrupted real-time measurement and control capability. The on-line GC analyzer operates continuously without the interruptions inherent in batch lab analysis, enabling constant process optimization and eliminating the need to switch between conservative and aggressive operating modes, thereby maintaining both quality and productivity continuously.
3Reliability
If total recycle is implemented until lab confirmation of on-spec product, then off-spec product can be prevented from reaching customers, but significant financial losses occur due to production delays
Solution Approach 1:
The patent replaces the mechanical batch sampling and lab analysis system with an automated on-line GC measurement system that provides continuous real-time data. This eliminates the time delay between product production and quality confirmation, allowing immediate detection of off-spec conditions and rapid response without requiring total recycle or production shutdowns, thereby preventing both quality issues and financial losses.
Solution Approach 2:
The system performs preliminary action by continuously monitoring impurity levels in real-time before off-spec product can be produced or distributed. The on-line GC system detects quality deviations immediately upon occurrence, enabling preventive corrective action rather than reactive responses that require product recall or total recycle, thus eliminating production delays while maintaining quality assurance.
4Reliability
If conservative process operation is maintained to ensure impurity levels remain below specifications, then product quality can be ensured, but production efficiency and profitability are reduced
Solution Approach 1:
The patent employs real-time feedback control where the on-line GC system continuously measures actual impurity concentrations and provides immediate data to the control system. This enables dynamic optimization of process variables based on real measurements rather than conservative fixed settings, allowing the process to operate at maximum efficiency while maintaining quality through active control rather than passive conservative operation.
Solution Approach 2:
The system introduces dynamics by transitioning from static conservative process settings to dynamic real-time control. The on-line GC enables continuous monitoring and adjustment of process variables based on actual impurity levels, allowing the process to adapt its operating conditions optimally rather than maintaining fixed conservative parameters, thereby achieving both quality assurance and maximum 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
The system enables real-time, accurate measurement of impurities at concentrations below 10 ppm, allowing for immediate adjustments to process variables, reducing the risk of off-spec products, and minimizing financial losses associated with production delays.
Implementation Method 1
A small volume of the liquid ethylene oxide is vaporized without heating the liquid ethylene oxide to a temperature at which polymerization is initiated.
Implementation Method 2
The vaporized ethylene oxide and impurities are carried by the carrier gas through a gas chromatograph
Implementation Method 3
A carrier gas flows through a gas chromatograph
Data Source
Figure 1~2
Figure 3~4
AI summary
Automated systems and methods for obtaining of the concentration of impurities in a liquid ethylene oxide product stream are shown and described. The systems and methods employ remote injection and flash vaporization of small volumes of liquid ethylene oxide into a carrier gas to minimize polymerization of the ethylene oxide and accumulation of polymerized ethylene oxide. Ethylene oxide peaks are diverted from the gas chromatograph effluent detector to stabilize baseline signal errors and avoid errors in the calculation of an impurity with an adjacent retention time peak. The systems and methods may be used for feedback, feedforward, dynamic matrix, and/or model-based predictive control of ethylene oxide purity. The systems and methods reduce lag times and errors associated with relying on laboratory analyses to make process adjustments.