Flow Measurement and Leakage Detection of Gaseous CO2

In order to combat the climate change caused by increasing emissions of CO2 from industrial processes, Carbon Capture and Storage (CCS) technologies have been accepted worldwide to address these pressing global warming concerns. So as to efficiently manage material and financial losses across the entire stream, accurate accounting and monitoring through fiscal metering of CO2 in CCS transportation pipelines are core and required features for the deployment of CCS technologies. Moreover, these technical requirements are part of the legal compliance schemes and guidelines from various regulatory bodies. This thesis reports experimental studies of two different metering technologies, an Averaging Pitot Tube (APT) and a Coriolis mass flowmeter (CMF), for CO2 flow measurement, together with the design and implementation of a CO2 flow calibration facility. A prototype system for the leak detection of the gas phase of CO2 is also developed.

A review of the methodologies and technologies for the flow measurement and leak detection of CO2 gas is firstly given, followed by the discussion of the main challenges and technical requirements in their applications. Based on this review, two flow metering technologies, APT and CMF, are selected for experimental studies and a calibration platform using both volumetric and direct mass measurement methods for the gas phase of CO2 is also developed. The APT and CMF were calibrated and evaluated in the test facility. Experimental results obtained in this test facility demonstrate that the instruments are capable of accurately metering gaseous CO2 within a measurement uncertainty of ±1.5%. Flow characterization of the fluid under wet and mixed components conditions were further assessed with both meters. Under wet CO2 flow, results obtained show that both flow instruments are subject to significant measurement errors. The APT gave an error of up to ±25%, for a liquid fraction of 20%, while the error of the CMF was up ±6%, for a liquid fraction of 10%. Further investigations show that these errors can, however, be corrected through simple and straightforward algorithms that can be easily incorporated into computing processes in the flowmeters. In binary gaseous mixture tests, the CMF proved to be very reliable in the gas combination processes and likewise in the metering of the CO2 mixture (? ±1%), while a higher degree of uncertainty was registered for the APT (? ±4%). Overall analyses from investigations confirmed the APT and CMF instruments as promising technologies for CO2 flow measurement and can be further improved for application in actual CCS conditions. In addition, this thesis describes experimental investigations of the leak detection of CO2 gas from a pipeline, with emphasis on full controllability and flexibility of the operational process. An imaging system using passive temperature change detection techniques is designed, implemented and evaluated. The effectiveness of the developed technique is examined on a laboratory-scale flow rig system. Results obtained from tests confirmed the operability of the system configuration and validation of the thermal imaging approach. Suggestions for future development and enhancement of the proposed techniques are finally given.