Desalination systems employing the distillation process have long since depended on basic shell and tube heat transfer technology. This basic form of heat transfer has been acceptable in the past, but as the economics of systems becomes more important, and as waters for desalination become more diverse, then the total cost aspect of the project becomes essential. An alternative heat transfer technology is now becoming more dominant in the desalination market - plate heat exchangers. Plate-type desalination systems have been in operation since 1967, and some 70% of the world＇s ships and offshore installations are using plate technology due to the advantages inherent in the system design. The plate concept applied in the Alfa Laval Water Technologies multi-effect plate (MEP), multi-effect thermo-vapour compression (TVC) and vacuum vapour compression (VVC) has distinct advantages over earlier technologies and offers owners and operators significant total cost savings. The high heat transfer coefficient achievable in the plate concept leads to relatively low heat transfer areas. This, along with the inherent low hold-up volume, leads to an extremely compact design giving a small footprint and corresponding to low civil costs. For most applications Alfa Laval applies titanium plates inside a duplex stainless steel vessel. Neither the Alfa Laval plate nor tubular units are designed to operate with waters containing high calcium sulphate. All heat transfer surfaces suffer if subjected to high sulphates, but the significant difference between the plate and the tube is that the plate can be completely cleaned on both sides. In this manner the heat transfer area always remains totally effective, removing any need to incorporate redundancy in design.