Electricity and Control July 2023

COVER ARTICLE

W ith a shift from fossil-fuel based systems to renewable energy sources also comes a shift in their transportation. The shift applies for pipeline leak detection systems too. Some pipelines transport 100% hydrogen and others a blend with natural gas. CO 2 can be transported as gas, liquid or in supercritical state. The leak detection system needs to be able to work with these different mixtures and phases. For classical leak detection systems, this is a problem. Negative Pressure Wave leak detection systems are affected due to damping in gas. Classical statistical systems are affected due to compressibility and linepack changes. This leads to long detection times or high thresholds. The systems will react with a loss of sensitivity or, in the worst case, with false alarms. This is a typical application for RTTM-based systems, which try to accommodate all the different products and pipeline properties in their calculations. However, if the fluid cannot be accurately modelled by the system, it will present false results. In the Extended Real-Time Transient Model technology (E-RTTM) developed by KROHNE, these disadvantages are compensated for by signature analysis. This makes the system less sensitive to inaccuracies in RTTM calculations. Thus, challenging pipeline conditions, product parameters or mixtures such as hydrogen blends leading to inaccuracies, become less important. In KROHNE’s PipePatrol the RTTM is used for filtering purposes and leaks are detected by pattern recognition techniques. Principle of E-RTTM As a manufacturer of measuring technology and established supplier of systems to the pipeline industry with more than 35 years of experience in leak detection and localisation systems, KROHNE developed E-RTTM. The Extended-Real Time Transient Model extends a feature generation module with leak signature analysis using leak pattern detection. An E-RTTM leak detection system creates a virtual image of a pipeline and uses standard process instrumentation for flow, temperature and pressure measurements. The hydraulic profiles along the virtual pipeline are calculated from the measured pressure and temperature values. The model compares the calculated flow values with the actual values from the flowmeters. If the model detects a discrepancy, the leak signature analysis module determines whether it was caused by changing pipeline operation, an instrument error, or a leak. Leak detection for hydrogen The leak detection system was installed on a power-to-gas project which was the world’s first demonstration plant for storing wind energy in the natural gas grid. As the leading leak detection system provider in Germany, KROHNE was recommended by an independent third-party authority to supply the leak detection system. The E-RTTM technology was selected due to its ability to measure leaks even in small quantities. This was the first power to-gas application equipped with a PipePatrol leak detection Leak detection for the energy transition

FEATURES: · Control systems + automation · Drives, motors + switchgear · Measurement + instrumentation · Safety of plant, equipment + people

Daniel Vogt, Dipl-Ing. (FH), MSc, Business Unit Manager, Pipeline Management Solutions, KROHNE.

Max Ihring, MSc, Product Group Manager, Pipeline Management Solutions, KROHNE.

system, in 2013. Since then, PipePatrol has been installed on more hydrogen pipelines.

Leak detection for carbon capture Natural gas from the Gorgon gas field contains around 14% naturally occurring CO 2 . Before converting the natural gas to LNG, the CO 2 is removed. To minimise the environmental footprint, the separated CO 2 is injected in a storage formation. A seven km long pipeline transports the CO 2 from the LNG liquefaction plant to the CO 2 injection wells. The requirement was to provide a pipeline leak detection system that provides timely and accurate leak information for the pipeline-segments between the LNG plant and drill-centres. KROHNE provided the E-RTTM-based leak detection system. The project involved unique conditions, such as the properties of CO 2 in supercritical phase and flow measurements done using orifice plates with limited rangeability. Summary KROHNE’s PipePatrol E-RTTM, is a leading technology for monitoring pipelines. It can be adapted to the different requirements of applications and thus produces better overall results. Signature analysis makes the system less sensitive to inaccuracies in the process and modelling of the fluid. The technology is industry-proven for liquid, gas and slurry applications. The smallest detectable leak rates are typically 0.5% or lower. Leaks are detected within seconds, confirmed within minutes. It also has an exceptionally low false alarm rate due to optimisation. Leak localisation is best-in-class. □

Changes in energy sources and transportation pipelines require a change in leak detection systems too.

For more information contact KROHNE South Africa. Visit: https://za.krohne.com/en

JULY 2023 Electricity + Control

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