multi-effect distillation

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In order to improve the production ratio (GOR or global output ratio: the quantity of distilled water produced in relation to the quantity of steam, expressed as kg of water produced per kg of steam used) and, accordingly, to lower freshwater production costs, we use the heat generated by the first effect vapour condensation in the second evaporator’s heating bundle, and then the heat generated by the second effect steam condensation in the third evaporator’s heating bundle, and so on. This cascade re-use of the steam output is only possible in exchange for a reduction in operating pressure at each effect, the final condenser working at the lowest pressure.

Increasing the number of effects will increase GOR because the same boiler steam produces water at each effect, but will increase boilemaking to be implemanted works. Therefore, a cost-effective optimum has to be found, mainly based on the cost of local energy.

Two-effect MEDSecured image
Figure 10. Two-effect MED