Instrumentation and measurement in gas dehydration: Controlling performance from inlet to outlet

Tunable diode laser absorption spectroscopy (TDLAS) is used for real‑time detection of moisture in natural gas. By directly monitoring the water content in the gas, operators and engineers gain clear, real-time insight into whether the system is meeting specifications and running efficiently. Non-contact optical measurement avoids contamination and sensor drift due to vapor impurities. TDLAS-based gas analyzers, such as the J22, ensure the highest accuracy and reliability under harsh environmental conditions. While providing rapid response to concentration changes, these analyzers are insensitive to changing stream composition.

Accurate ultrasonic flow measurement is essential for controlling and verifying performance in gas dehydration units. At the inlet, it helps ensure the gas velocity is kept in the design limits of the glycol contactor, therefore supporting stable gas-glycol contact and reducing the risk of foaming, flooding or carryover. At the outlet, accurate flow data ensures stable operation and helps detect abnormal pressure drops or restrictions caused by fouling or carryover effects. Ultrasonic gas flowmeters such as our Prosonic Flow G 300 offer key advantages compared to mechanical meters: they are non-intrusive, exceptionally robust, suitable for wet gas and fluctuating feed gas composition. Ultrasonic flowmeters also ensure high accuracy as well as integrated advanced gas analysis capabilities.

Pressure and temperature transmitters provide decisive insight into absorber performance, glycol regeneration, gas flow behavior and, therefore, overall process stability. In the contactor, pressure and temperature directly influence water absorption efficiency and gas quality. Monitoring these variables, together with differential pressure, helps detect foaming, flooding, fouling and turbulences as well as poor gas‑liquid contact at an early stage. iTHERM ModuLine TM131 ensures fast response times and captures dynamic process changes reliably thanks to iThERM QuickSens technology. Its wide measuring range makes it suitable for use in absorbers, flash tanks and regenerators. Deltabar PMD78B provides accurate pressure measurement and condition monitoring with Heartbeat Technology as well as long-term measurement stability and robustness.

Coriolis flowmeters provide direct mass flow measurement independent of temperature, pressure or density changes. This is especially valuable in dehydration processes where glycol properties can vary during regeneration or due to contamination.

High accuracy at both low and variable flow rates makes these instruments well suited for lean and rich glycol circulation monitoring. Stable flow measurement helps operators maintain proper glycol-to-gas ratios, improve absorber efficiency and reduce the risk of glycol carryover or off-spec gas. Another major benefit is the ability to measure multiple process variables simultaneously: density measurement is particularly valuable because it allows operators to monitor glycol concentration and regeneration performance in real time. Changes in glycol density can indicate water contamination, poor regeneration efficiency or process instability. In addition, Coriolis flow meters such as Proline Promass Q 300 offer excellent long-term stability and space-saving installation.