Development of Multiple-Effect Seawater Concentrator of Simple Construction

—Construction and Performance of a Quintuple-Effect Concentrator—

Abstract

A quintuple-effect seawater concentrator consisting of four distilling layers and a top evaporating fabric was constructed and its performance was tested. In this concentrator, the bottom surface of 1 m×2 m is heated up to 100°C, while the top surface was cooled in 23°C air by free convection accompanied by evaporation. Each distilling layer was constructed with a mesh spacer of plastic 5mm thick placed between an evaporating fabric and a condensing fabric, and in this construction, it was found that no condensate leaked to the evaporating fabric and no concentrate leaked to the condensing fabric. The total evaporation in this concentrator was 15.4 kg/h, and it is suggested that the evaporation increases as the area of the mesh spacer through which the vapor diffuses is increased and as the cooling on the top surface is increased. The separating plate between the distilling layers is a silicone-coated, hot-dip zinc-coated steel sheet. While this plate was kept in contact with the seawater-soaked evaporating fabric in this test, it is not in rust.