Koreans devoting R&D cash to gas-hydrate desalination
Korea's Minister of Land, Transport & Maritime Affairs, Kwon Do-youp, unveiled "a new paradigm" in desalination development when he announced on 4 October 2011 that Korea was pursuing gas-hydrate desalination.The Korean government maintains that its new process can be 30-50% cheaper than current evaporation or membrane technologies.
The Korean Institute of Industrial Technology (Kitech) is to receive up to Won 11 billion (US$ 9.2 million) for the next five years to develop core technologies for the technology. In addition, private companies have been invited to take part, at an early stage of research, in a project to set up a 20 m³/d test plant to help promote early commercialization.
Earlier this year, five researchers from Kitech, with a colleague from Korea Basic Science Institute, published a paper A new apparatus for seawater desalination by gas hydrate process and removal characteristics of dissolved minerals (Na+, Mg2+, Ca2+, K+, B3+) in Desalination journal (published online on 23 February 2011).
In it they describe a novel apparatus that continuously produces and pelletizes CO2 hydrates by a squeezing operation of a dual-cylinder unit, which is able to extract hydrate pellets from a reactor containing hydrate slurries.
"In a single-stage hydrate process," say the researchers, "72-80% of each dissolved mineral was removed in the following order: K+ > Na+ > Mg2+ > B3+ > Ca2+. Our results also showed that ion rejection by the hydrate process strongly depends on the ionic size and charge."
They concluded that their study illustrated that this method could solve the separation difficulty between hydrate crystals and concentrated brine solutions, thus allowing it to be applied for more effective desalination processes.
Gas hydrate commonly forms during offshore gas drilling, when water is condensed in the presence of methane at a high pressure and low temperature.
Research on gas-hydrate desalination is also being carried out by Oak Ridge National Laboratory in the USA, working with BC Technologies Ltd.