Hydrogen will play a key role in the energy transition. A first step in the decarbonisation of electricity and heat generation as well as other industrial processes will be the injection of green hydrogen into the natural gas networks. For the network operators, this changes mean an enormous challenge, not only with regard to the material integrity of the pipeline infrastructure, but also in terms of durability and functionality of the installed measurement technology. In our paper, we will demonstrate a new approach to using clamp-on ultrasonic technology not only to measure flow non-invasively, but also to simultaneously determine the compressibility, density and viscosity of the gas flowing in the pipe.

Clamp-on ultrasonic meters are widely used in high pressure natural gas systems for non-fiscal purposes Nevertheless, common clamp-on gas flow meters are blind to changes in gas composition and therefore rely on external determination and input of the current gas quality. Gas chromatographs for the precise determination of composition are only available to a limited extent for organisational and economic reasons. Many non-fiscal gas flow measurement points will therefore lack real-time data to determine the standard volume flow and transported caloric content.

FLEXIM designed an algorithm based on AGA 10 and GERG 2008 sound speed tables to calculate within the ultrasonic flow meter the molar mass, the compressibility, and the density of the natural gas stream in real-time. This enables the flowmeter to compensate its readings in case of changes in the gas composition without any time delay.

The presentation will show the development of the algorithm and will highlight first test result on natural gas and natural gas mixes with renewable gases.