Spray enhanced demisting (SED)

A new innovative and efficient system has been studied, realized and tested by SWS’s engineers for the production of top quality distillate TDS<0.1 ppm by evaporation of seawater in both MSF and MED desalination plants. This system is based on the combined effect of scrubbing the vapor outflowing from the demisters (with a spray of accelerated droplets of distillate) and of the mechanical coalescence in a further layer of demisters. The key factors of the main scrubbing process are the highest rate of hitting droplets velocity, the dimensions of the droplets and the number of droplets to be large enough to balance the statistically low impact efficiency. The arrangement of the system is very simple and has been protected by a patent since June 2001, registered by SWS. The benefits provided by this innovation are quite remarkable both for the dramatical reduction of the investment cost and for the high reliability of the plants whenever the fresh water product is requested for industrial services, such as make up to HP steam generators, and process water for the chemical industry being the suitable quality ensured without any further treatment of the distillate.

• The SED system is now successfully tested and ready for commercial application. Its cost is proven to be dramatically lower than any polishing plant to be installed for further treatment of the distillate, whenever the requested purity exceeds 1 ppm. The reliability of the SED system is based on its mechanical simplicity and by far exceeds the reliability of any resin treatment plant. • The environmental impact of the SED system is much more favorable than any resin treatment system, since the resin requirs the consumption and disposal of the regenerating chemicals. • The SED system is protected by the patent registered by SWS, but will be anyway available to any supplier of desalination plants, upon a fair cooperation agreement. • The SED system is applicable to both MED and MSF desalination units. Partial application on single stages/effects is possible and recommended whenever the combined service is to be provided for industrial end civil utilization. In this case a separate extraction of the distillate produced in the SED equipped stages/effects, is to be ensured by adequate additional pumps. • The SED is also applicable in most of the cases to the existing plants, providing that the geometry of the stages/effects is suitable for the installation of the additional demister. The engineers of SWS are available for any survey and for any review of drawings, and accordingly confirm the possibility of installation, as well as determine the ensured purity of the fresh water and the reduction of the total maximum production rates of the plant.