Online Determination of Mercury in Unstabilised Hydrocarbon Liquid Streams

Warren Corns, from PS Analytical, will present 'Online Determination of Mercury in Unstabilised Hydrocarbon Liquid Streams' at PEFTEC, November 18th-19th 2015.

Unstabilised hydrocarbon liquid streams such as unstabilised condensate present particular challenges for sampling and determination. If the liquid sample is depressurised, a portion of the sample is vaporised, producing a two phase sample for determination. Mercury can be associated with both the gas and liquid portions of the sample. The most accurate mercury measurement is therefore obtained when the analysis is performed at process conditions. 

Conventionally, determination of liquid process streams which are gas-liquid mixtures when depressurised is difficult due to the need to characterise two separate phases and combine the results. This can lead to high measurement uncertainty and complicated procedures. 

This paper describes a newly developed fast loop sampling system with self-cleaning filtration, a novel auto-injection system designed to introduce the sample to the analyser at process pressure to avoid the issues associated with depressurisation. Sample is collected in a flow injection sample loop at process conditions. A pressurised sample flows through an injection valve, where aliquots of sample are introduced to the vaporisation chamber which allows the volatilization of the sample so that Hg is collected using high temperature amalgamation. After the pre-concentration step and selective separation of the sample matrix the mercury is thermally desorbed to the Hg analyser which is based on atomic fluorescence spectrometry. 

This paper will describe a fully developed ATEX/IECEx zone 1, certified equipment. The system can be configured for up to eight sample streams. Examples and results will be provided from instruments installed in the field.

This talk will take place Thursday 19th November, 2.30-3.00, Room 2 at PEFTEC.