Gas quality measurement of gas mixtures containing hydrogen with ultrasonic flow meters - experiences, challenges and perspectives

The quantity of natural gas with admixed hydrogen is gaining importance in the context of decarbonization of energy supply. Flow metering using ultrasonic gas meters has set a new standard in terms of reliability, durability, and measurement accuracy, and is widely used in both the natural gas and process gas industries. However, due to its very high speed of sound and low density, hydrogen presents a physical challenge for volume flow meters. Both the challenges and the necessary adaptations to the device design and signal analysis of the ultrasonic meters are discussed. It is shown that appropriately adapted ultrasonic meters are well suited for hydrogen-containing gases as well as for measuring pure hydrogen. In addition to the primary measurement values and the required high accuracy, ultrasonic meters offer further advantages such as a large flow range, very high flow rates ("energy-equivalent transport of hydrogen"), low pressure drop and diagnostic capabilities. In particular, the precise measurement of speed of sound, which is primarily used to validate accurate flow measurement, also provides opportunities for gas composition analysis. For example, the hydrogen content can be determined when the composition of the natural gas is known. This provides a sustainable alternative or complement to hydrogen content measurement.