Continuous online process analytics with multiplexing gas chromatography by using calibrated convolution matrices.

Area of Science:

• Analytical Chemistry
• Chemical Engineering
• Process Control

Background:

• Traditional gas chromatography (GC) methods are too slow for real-time control of fast-changing chemical processes.
• Quantitative analysis of trace components often requires lengthy GC analysis times (minutes to an hour).
• Process Analytical Technology (PAT) demands faster, more precise measurement techniques for safe and efficient chemical operations.

Purpose of the Study:

• To develop a multiplexing gas chromatography (mpGC) technique to increase measurement frequency.
• To address the limitations of conventional GC response times in dynamic process environments.
• To improve the efficiency of chemical process control through reduced dead time in control loops.

Main Methods:

• Developed an mpGC technique for systems with systematic non-linear responses.
• Implemented superimposed chromatogram acquisition by injecting samples before previous ones fully elute.
• Introduced a convolution matrix calibration to suppress systematic errors and correlation noise.
• Achieved a computed chromatogram representing an average over the last five injections.

Main Results:

• The mpGC technique increases sample throughput by a factor of three compared to conventional GC.
• Calibration of the convolution matrix effectively suppresses correlation noise from systematic errors.
• Remaining noise in computed chromatograms is primarily due to changing sample concentrations.
• Achieved faster measurement cycles suitable for real-time process monitoring.

Conclusions:

• The developed mpGC technique offers a significant advancement in process analytical technology.
• This method enables faster and more frequent quantitative measurements for improved chemical process control.
• mpGC provides a viable solution for analyzing fast-changing processes where conventional GC is inadequate.