With a shift from fossil-based systems to renewable energy sources also comes a shift for transportation. This is also true for pipeline leak detection systems.
Pipelines transport 100% hydrogen or a blend with natural gas. CO2 can be transported as a gas or liquid, or in a supercritical state. As a result, 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 by damping in gas. Classical statistical systems are affected by compressibility and linepack changes. This leads to long detection times and high thresholds. The systems react with a loss of sensitivity, or in the worst case, with false alarms. Real-time transient model technology (RTTM)-based systems consider all the different products and pipeline properties in their calculations. However, if the fluid cannot be accurately modelled by the system this leads to false results.
The Extended RTTM (E-RTTM) system was developed by KROHNE, an established supplier of measuring solutions to the pipeline industry, with over 450 installations and more than 35 years of experience in pipeline leak detection and localisation systems. It combines a feature generation module with leak signature analysis using leak pattern detection. Any disadvantages are compensated for by signature analysis. E-RTTM makes the system less sensitive to inaccuracies in RTTM calculations. Thus, inaccuracies arising from challenging pipeline conditions, product parameters or mixtures like hydrogen blends become less important. KROHNE’s PipePatrol E-RTTM is a leading technology for the monitoring of pipelines. The RTTM is used for filtering purposes, and leaks are detected by pattern recognition techniques. The technology is applicable to liquid, gas and slurry applications.
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. The smallest detectable leak rates are typically 0,5% and below. Leak detection time is in seconds, and confirmation within minutes. The false alarm rate is exceptionally low, and leak localisation is best-in-class.
Leak detection system for hydrogen
KROHNE’s 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 had been recommended by an independent third-party authority to be the supplier for the leak detection system. The E-RTTM technology was selected due to its ability to measure a gas, even in small leak quantities. This was the first power-to-gas application equipped with a PipePatrol leak detection system. Since then, PipePatrol has been installed on many more hydrogen pipelines.
Leak detection system for carbon capture
Natural gas from the Gorgon gas field contains around 14% naturally occurring CO2. Prior to converting the natural gas to LNG, the CO2 is removed. To minimise the environmental footprint, the separated CO2 is injected in a storage formation. A 7 km-long pipeline transports the CO2 from the LNG liquefaction plant to the CO2 injection wells. The requirement was to supply a pipeline leak detection system that provided 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 CO2 in a supercritical phase, and flow measurements done by orifice plates with limited rangeability.
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