Publications

Sampling and analysis of small quantities of mercury in natural gas from various streams of processing, liquefaction and subsequent handling require specialized equipment and skill. As is the case with many other micro analytical methods, the determination of small quantities of mercury requires special precautions to ensure complete recovery of the element, and to prevent contaminations during sampling or analysis.Most of the current analytical methodls for deter-. mining mercury in natural gas and relaled samples are the modifications of methods developed by environmentalists, toxicologists, and geochemists.The Methods Developed Include:(a) Drager tubes.(b) Reduction of mercury to elemental state in an aqueous solution and measurement by cold vapor atomic absorption spectrophotometry.(c) Collection of mercury on gold collector (amalgamation) for subsequent determination by utilizing gold film detector, based on the phenomenon that a thin gold fiim undergoes a significant increase in resistance upon the absorption of mercury vapor.(d) Collection of mercury by silver wire or gold plated wire, for subsequent determination by ultra violet photometer operating at 253.7 nm. Continuously direct mercury measurements of gas streams by dual beam, ultra violet photometers.The methods used by P.T. Arun Natural Gas Liquefaction Company include the fiist three. The repeatability, accuracy and sensitivity of the individual methods has been evaluated for this specific application and are reported in this paper.Because of the specific circumstances at P.T. Arun including interferences, from acid gases such as H2S, it is concluded that the determination of small quantity of mercury in natural gas by gold film detector provides the most reliable results.