Low‐grade heat driven desalination plants are capable of providing reliable and sustainable water solutions for remote communities, mine sites and water intensive processes used by industry. In certain situations reverse osmosis systems cannot meet the supply owing to various factors such as extremely high salinity, presence of toxins or radioactive compounds and lack of a suitable energy source.
Steam is a valuable and expensive energy resource, particularly in alumina refineries. Any process capable of capturing this resource can reduce production costs and greenhouse gas emissions simply by reducing fuel consumption. One of the main uses for steam in refineries is in evaporation units, which re-concentrate process liquor back to the main process circuit for further digestion. It can also be used to produce wash water.
A technology capable of overcoming reverse osmosis system limitations and which can utilise waste heat/steam is multi effect distillation (MED). A novel design has been developed by UWA which could boost the efficiency of standard MED by over 30% in terms of freshwater yield with a standard coolant temperature of 20°C. This can be achieved by exploiting the geothermal bore heat sources or waste heat/steam that is produced by refineries.
Advance the existing MED technology towards commercialisation by building and testing a 1 m3/day first generation two‐effect prototype.
A two-stage cascaded thermal desalination pilot plant was constructed to produce 1 m3/day of pure water from a saline feed and this unit was successfully commissioned and tested over a range of heat source temperatures (63°C–93°C) and cooling water temperatures (20°C–35°C). The result was an increase in fresh water production over a single stage system of between 33% and 57% dependent upon the operating conditions.
A second novel process was designed involving flash-boosted thermal-vapour-compression multi-effect-evaporator system, aimed at exploiting the waste heat streams available in the refinery. The process was bench marked against the currently used system and it showed a 370% increase in thermal performance. Capital cost analysis demonstrated a 10% reduction in the condensate production rate and 8% increase in process liquor production rate. Overall this process showed it is possible to save an additional 16% of the live steam consumption for the whole refinery plant.
The two-stage pilot plant will be tested under the refinery’s operating conditions and if successful, be commissioned onsite for incorporation into the refinery’s processes.
The technology has been protected with a number of patents and patent applications. The investigators are working with South32 as an industrial partner to undertake a pilot scale test program that is expected to be completed in late 2016.
Further commercialisation opportunities are being sought. For more information please contact the Principal Investigator.
Total Value: $1,127,686 (cash and in-kind contributions)
Principal Investigator: Professor Hui Tong Chua
Title: Development of a novel low grade heat driven desalination technology
Length: 54 months
Personnel: 28 collaborators contributing 22.0 FTE
- 2016., Rahimi, B. A novel flash boosted multi-effect distillation process. PhD thesis, The University of Western Australia.
- 2016. Rahimi, B., et al. A novel low grade heat driven process to re-concentrate process liquor in alumina refineries. Hydrometallurgy. In press.
- 2015. 10th International Alumina Quality Workshop. Perth, Australia.
- 2015. International Desalination Association World Congress on Desalination and Water Reuse. San Diego, USA.
- 2015. Christ, A. A novel sensible heat driven desalination technology. PhD thesis, The University of Western Australia.
- 2015. Christ, A., et al. Application of the Boosted MED process for low-grade heat sources — A pilot plant. Desalination 366:47-58.
- 2015. Christ, A., et al. Boosted Multi-Effect Distillation for sensible low-grade heat sources: A comparison with feed pre-heating Multi-Effect Distillation. Desalination 366:32-46.
- 2015. Rahimi, B., et al. Thermo-economic analysis of two novel low grade sensible heat driven desalination processes. Desalination 365:316-328.
- 2014. Rahimi, B., et al. A novel process for low grade heat driven desalination. Desalination 351(0): 202-212.
- 2014. Christ, A., et al. Thermodynamic optimisation of multi effect distillation driven by sensible heat sources. Desalination 336(0): 160-167.
- 2014. Christ, A., et al. Low-grade waste heat driven desalination technology. International Journal for Simulation and Multidisciplinary Design Optimization 5: A02.
- 2014. Waste heat put to work for freshwater. Science network WA.
- 2014. Thermo-Economic Analysis of Two Novel Low Grade Heat Driven Desalination Processes. Technical report.
- 2013. The American Membrane Technology Association and The American Water Works Association Membrane Technology Conference and Exposition. San Antonio, Texas.
- 2013. Geothermal Desalination – Part 1: Development of a techno-economic model. Technical report.
- 2013. Geothermal Desalination – Part 2: Case Studies in Morocco and Australia. Technical report.
- 2013. International Desalination Association World Congress. Tianjin, China.
- 2013. Maddock, J. A novel low-grade heat driven multiple-effect distillation technology. Honours thesis, The University of Western Australia.
- 2012. Group of Eight and China 9 Water, Water Management and Sustainable Futures Forum. Brisbane, Australia.
- 2012. 5th International Desalination Workshop. Jeju, China.
- 2012. Evolving Energy – International Energy Foundation International Energy Congress. Sydney, Australia.
- 2012. Association for Simulation and Multidisciplinary Design Optimization 4th International Conference on Multidisciplinary Design Optimization and Application. Xi’an, China.
- 2011. Wang, X., et al. Low grade heat driven multi-effect distillation technology. International Journal of Heat and Mass Transfer 54(25-26):5497-5503.