From Liquefied Natural Gas Production to Saturn’s Moon Titan

Australia is expected to become the world’s largest liquefied natural gas (LNG) producer in 2019 as forecast LNG exports increase to 74 million tonnes per year, according to a report by Reuters. However, the production of LNG is technically demanding, as it requires the exploitation and detailed understanding of phase equilibrium in multicomponent mixtures at extreme conditions with high pressures (over 60 bar) and low temperatures (down to -162 degrees C).

Here at the Australian Centre for LNG Futures, PhD student Arman Siahvashi has developed an innovative apparatus to visually measure the freezing and melting temperatures of hydrocarbons at cryogenic temperatures, data which are crucial to solve one of the major problems facing LNG industry: unscheduled plant shutdowns due to the blockages caused by the freeze-out of heavy hydrocarbons. Accurate measurements of freeze-out under conditions relevant to LNG production is extremely challenging. The apparatus, detailed in the Journal of Chemical and Engineering Data utilizes a cold finger attached to a Peltier module to accurately control and measure freeze-out conditions at pressures up to 200 bar and temperatures down to -180 °C. This novel approach has increased the accuracy and improved the uncertainty of such measurements compared to the traditional techniques and is eliminating knowledge gaps relating to problematic compounds not previously considered.

Arman’s work has also attracted attention from researchers at NASA’s Jet Propulsion Laboratory (JPL) due to its relevance in understanding and exploring Saturn’s giant moon Titan. Data from the Cassini-Huygens spacecraft have revealed Titan’s landscape is constructed from organic molecules such as benzene that are eroded by a weather cycle of methane rain, cryogenic hydrocarbon rivers, and lakes. This makes Titan the only object in the Solar System aside from Earth with stable standing bodies of liquid on its surface with temperatures down to -180 oC. Studies of Titan’s surface evolution require precise measurements of equilibrium solubilities at cryogenic temperatures which are also a critical factor for the potential of non-aqueous surface life. Dr. Michael Malaska, chief investigator of NASA’s Planetary Ices Group, commented: “Arman’s novel measurement technique allows a high precision measurement on a wide variety of organic compounds, not just the ones that have chromophores or can be easily detected in solution. We are incredibly excited to be able to collaborate with him, and look forward to his measurements providing key inputs for understanding Titan geology and chemistry. In addition, his measurement values will also provide us with instrument performance requirements for future lake and sea mission proposals to Titan”.