This paper deals with the technological development of the falling film vertical tube evaporation and in particular with the Snamprogetti process. After a brief indication of the successful results obtained in the Taranto plants, a presentation is made of the combination of a vertical tube evaporation plant with an existing multi-stage flash plant, with a view to improving its economics in terms of efficiency and production. Moreover, special attention is paid to the advantages obtainable from the multiple effect operating at high concentration factors.