Decarbonisation Technology - November 2022

Process gas analyser for measuring hydrogen concentration

A process gas analyser, based on near-infrared tunable diode laser absorption spectroscopy, has been developed to measure hydrogen in production environments

Airat Amerov and Michael Gaura AMETEK Process Instruments

T he human population of planet Earth is expected to reach eight billion by the end of 2022 or early in 2023, depending on the reference source. This means that, since the birth years of the authors, nearly twice as many people are occupying the same amount of space. However, most of us do not realise that, in the same time frame, global energy consumption has tripled. Thankfully, energy suppliers have continued to adapt and provide us with reliable and safe power, as well as heating, cooling, and transportation fuels, as our population and energy consumption habits have increased. As our understanding of the environmental impacts of the increasing energy requirements has evolved, a focus has been placed on reducing carbon utilisation and release from energy suppliers as well as end users. One ongoing transition that has secured billions of dollars in investment and spending is replacing some portion of fossil fuel or coal-based energy sources with hydrogen. Recognising that there are a variety of processes to produce hydrogen (the ‘rainbow’ – green, blue, brown, grey), this article focuses on a technology (tunable diode laser absorption spectroscopy (TDLAS)) that can be used to analyse the concentration of hydrogen in almost any method of hydrogen production, transportation, and storage. A new process gas analyser, based on near- infrared TDLAS, was developed and tested for the measurement of hydrogen in production environments. TDLAS is a non-contact optical technique with long-term stability,

Figure 1 5100 HD Analyzer

high specificity, and considerable sensitivity. TDLAS has been proven for several decades in many energy production and emissions monitoring applications. The low operating expense (OpEx) – no consumables, long-life optical components, and minimal maintenance requirements – has driven its acceptance as a preferred measurement technology. Measurements of hydrogen were made with this gas analyser in sample matrices corresponding to nitrogen. Reliable performance was demonstrated over a wide range of analyte concentrations and under a variety of pressure levels in the sample cell of the analyser. The hydrogen measurements yielded an accuracy of 2% full-scale range over a concentration range of 0-100%. The principal objective of the work reported here is to characterise a new TDLAS- based extractive analyser with an all-digital