Waste energy utilisation

Leader

Challenge

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.

Investigation 

Advance the existing MED technology towards commercialisation by building and testing a 1 m3/day first generation two‐effect prototype.

Outcomes

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.

Future Direction

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.

Technology Readiness

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.

Partner


 

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

Related Project: Pre-feasibility investigation of water and energy options utilising geothermal energy, multi-effect distillation and reverse osmosis

Further Information

FR1 UWA Chua Summary Poster

Project Summary Poster – geothermal

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