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Measuring water in glycols (MEG/TEG) during glycol dehydration

Process analysis - Oil & Gas

Real-time monitoring of water levels using a solid state FTIR-based sensor

For the Petroleum-based industries, glycol dehydration is a key process in the production of petrochemical products.  Standard methods of measuring water in glycols (MEG/TEG/PEG) have their challenges that force many to juggle speed of results versus expense and accuracy. Manufacturers are looking for a better way to monitor this process. Keit has developed the solid-state IRmadillo™ FTIR spectrometer for in situ monitoring of industrial processes to provide continuous real-time results.

The need for a robust solution

Spectroscopic measurements typically fall into three main types for process analysis: near infrared (NIR), mid-infrared Fourier transform (i.e., FTIR) and Raman spectroscopy. Both Raman and NIR instruments can be used in industrial processes, but they lack any real sensitivity for water. Conventional FTIR spectrometers are more sensitive to water but necessitate the use of fragile fibre probes, which are wholly unsuited for the industrial environment.

What’s the solution?

By making an FTIR instrument sensitive enough to measure water yet robust enough to handle vibrations. Here we present a robust and rugged FTIR-based sensor that is inherently vibration resistant and reliable. This is achieved by the avoidance of all moving parts and fibre probes, offering a tough and innovative method for process monitoring.

IRmadillo and Analysis of MEG & TEG

The Keit IRmadillo is an innovative solid-state technology certified safe for use in hazardous environments.  This makes it ideal for application in petrochemical manufacturing. Suitable insertion points for the IRmadillo into a typical glycol dehydration process are shown in Figure 3.

How well can it measure water in glycols?

The IRmadillo was used to analyse individual samples of monoethylene glycol (MEG) and triethylene glycol (TEG) with known concentrations of water.  Samples were acquired and spectra were used to build chemometric models. The data were analysed using orthogonal signal correction (OSC) and partial least squares (PLS) models to predict the concentrations in real time.

IRmadillo water in MEG

IRmadillo water in TEG
Figures 1 & 2 – Plots of measured values vs reference values for water in MEG (top) and TEG (bottom)

After analysis, the results show that the IRmadillo produced results showing an excellent correlation between the measured and reference samples. This means that the IRmadillo can accurately measure the water concentration with great precision.

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The results showed that it is possible for the Keit IRmadillo to monitor drying of MEG & TEG to >99.985 and 99.990% respectively.


Figure 3: A simplified schematic showing the glycol dehydration process and possible insertion points of the IRmadillo


The IRmadillo™ is an effective, accurate and precise sensor for measuring water in glycols. It has been demonstrated directly for monoethylene glycol and triethylene glycol, but the technique is applicable to any glycol dehydration mix. It is possible to monitor water contents to 139 ppm in MEG and 96 ppm in TEG.

Get the Application Note

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