(More) Effective Contaminant Measurement in LNG Processing

Presented at 2017 Spring Conference held at Hilton Garden Inn, Milan North on 17 - 19 May 2017 by Tony Wimpenny, Orbital Gas Systems
Safe and efficient gas processing requires a detailed understanding of the characteristics of the gas prior to treatment, and verification that the treatment has been completed to the required specification. In processing natural gas to LNG, it is a necessity to ensure that moisture is removed to very low levels, id ice build-up in the cryogenic refrigeration plant. Similarly, mercury must be completely removed as it can progressively eat through aluminium heat exchangers in a destructive and potentially catastrophic self-propagating chemical process. Unscheduled plant shutdown or maintenance operations cost millions of dollars every year, and the potential threat to personnel health due to mercury exposure makes the issue even more critical. Typically, pre- and post- bed removal conditions are monitored by very accurate analysers. However, both moisture and mercury are notoriously difficult to measure at trace levels due to their tendency to adhere to any rough surfaces, contamination or other substrates not purpose-built for the application. This paper looks at the challenges measurement impose on a sampling system and a number of techniques that can be employed to mitigate problems.