Final design of an advanced solar dryer for salt recovery from brine effluent of a desalination MED plant

The ongoing AQUASOL-Enhanced Zero Discharge Seawater Desalination using Hybrid Solar Technology (EVK1-CT2001-00102) [1] project is one more attempt at puffing solar energy to use in water desalination, improving the economics and the environmental performance of a MED desalination plant [2]. Within the project, an advanced solar dryer is being studied, allowing for brine concentration and/or ultimate salt recovery from the MED brine effluent, providing one more product - salt. This is meant to be achieved using the fact that the effluent of the MED plant has a higher salt concentration than the initial sea water, and that the whole system might be integrated in a classical Saltworks, with the potential for substituting one or more intermediate steps in the conventional process. Taking into account the specificities of salt production in a classical Saltworks, an optimised design based on a passive approach was studied, allowing for an improved system able to deal with a constant brine flow. The construction and preliminary evaluation of a small Advanced Solar Dryer (ASD) prototype [4] permitted a performance assessment of five different configurations for a covered evaporation channel, leading to a final design of a full-scale ASD prototype at Lesvos (Greece). The assessment of ASD monitoring results over changing weather conditions also allowed for a refinement of the ASD operation simulation model, namely through a better knowledge and description of ASD internal airflow head loss. A 1:25 scale model of the final ASD prototype was thoroughly studied in a wind tunnel. This test enabled the evaluation and introduction of additional internal flow enhancement strategies. After the prescribed final design, the ASD prototype will be erected and deployed in June, to be operating under brine concentration conditions. Design choices and construction strategies of the full-scale ASD prototype will be presented. First monitoring results and "present-state" simulation for a yearly operation campaign will be further on addressed, after collection of monitoring results under real operation conditions.