Experimental evaluation of various flow meters using gaseous CO2

The need for accurate flow measurement within the Carbon Capture, Utilisation and Storage (CCUS) transport network is widely reported and understood as a requirement of Emission Trading Schemes and commercial contracts. In meeting this requirement, traceable calibration is needed in conditions which closely mimic the process conditions. However, currently accredited calibration facilities cannot meet the conditions for calibrating in gaseous CO₂ and so a likely alternative solution for these custody transfer flow meters is to be calibrated with an alternative fluid and the calibration transferred. In this article, which was produced under the framework of the EMPIR project “Metrology for Decarbonising the Gas Grid”, the authors will investigate this approach with a number of flow meters tested in natural gas, nitrogen gas and finally in carbon dioxide gas at varying pressures. The results of which will suggest that orifice and Coriolis meters can be calibrated in another fluid however, an ultrasonic meter would require further work and potentially require calibration in CO₂. This article will also investigate the effects of impurities in a CO₂ gas stream for a rotary displacement flow meter and a thermal mass flow controller compared against a piston prover which provides a primary reference flow standard.