By Liz Mcgrath and Eric May
IT MAY be the world’s largest natural gas project, however not all the Gorgon focus is on the gas fields lying off the northwest coast of Western Australia.
More than a thousand kilometres away, Professor Eric May from the University of Western Australia (UWA) has led a small team of scientists in series of global breakthroughs on the behaviour of gases and liquids, discoveries set to help optimize the way LNG is produced.
The research project, funded by Chevron and the Australian Research Council, has brought together some of the foremost researchers in the field and required the commissioning and construction of world leading high-pressure experimental equipment in the UWA laboratories.
For Dr May, an expert on the thermodynamics and measurement of fluid properties, particularly those relevant to gas processing and LNG production, the timing was impeccable.
“The prospective oil and gas activity in the northwest of Western Australia is on a truly global scale,” he said. “With six major projects currently under construction, Australia will be the world’s second largest LNG exporter by 2020, producing 60-100 million tonnes per annum.
“To capitalise on this resource we need effective and safe technology and part of this is how well operators can simulate or predict how an LNG plant is going to perform in terms of separating out the various components of the natural gas stream.”
Beginning back in 2007, UWA researchers focused on the cryogenic distillation tower at the heart of an LNG plant, known as the ‘scrub column’.
“This column is designed to prevent significant concentrations of compounds heavier than ethane from entering the main cryogenic heat exchange where liquefaction occurs, before the LNG is then de-pressurised and sent to storage,” Dr May said.
“If operators leave the top part of the scrub column at too high a concentration, heavier compounds can freeze out and block the narrow tubing networks in the cryogenic heat exchanger, causing unplanned shutdowns with severe consequences in terms of time and money.”
It is possible to drive the scrub column to prevent this from happening but this requires the use of extra power. Predicting the concentrations of heavy hydrocarbons leaving the top of the scrub column is especially difficult as the operating temperature and pressure are often near the fluid mixture’s thermodynamic critical point.
Dr May’s team set about developing the state-of-the-art measurement systems needed to capture the most accurate data available on the behaviour of fluid mixtures under these conditions.
“The data was then used to construct more accurate and efficient models of fluid properties inside the scrub column,” said Dr May.
“This advance will not only enable LNG operators to avoid expensive delays but also provide engineers with the knowledge needed to lower the energy required to produce the LNG, reducing the environmental footprint of such major developments.”
It’s been heady work for the recipient of the 2010 WA Early Career Scientist Award and the 2012 Prime Minister’s Award for Physical Scientist of the Year, who also holds the Chevron Chair of Gas Processing at UWA.
“At the beginning, you never know for sure exactly how you’re going to overcome the challenges,” Dr May said. “But then one day you’re looking at the new data and you suddenly see the answer. This project has become increasingly enjoyable and rewarding as we’ve gone from very fundamental science to an outcome that’s very applied.
“We’re now looking at building a micro scale replica LNG plant for research, training and education that again will be unique in the world,” he said.