A new method for the treatment of the reverse osmosis process, with preheating of the feedwater

This paper summarises our investigations on the conceptual studies of the Reverse Osmosis (RO) process with preheating of the feed-water, which is expected to lead to lower specific power consumption and higher water production, thus further reducing the cost of desalination by this advanced RO process. There are, however, no adequate calculation methods to take into account the effect of temperature on the RO system performance parameters such as the recovery ratio, feed pressure, feed flow and the permeate salinity. The work presented here tries to fulfil this need through the elaboration of mathematical correlations expressing the variation of these parameters as functions of the input parameters such as feed temperature, feed salinity, and the desired production capacity. The principle of the method used is to first dimension the RO system with the help of the software ROSA and the membrane SW30 HR380 for a series of calculations (504 cases) giving the variation of the above performance parameters for a large range of the input conditions. Numerical methods were then used to obtain the correlations giving the complete variation of the performance parameters as functions of the input parameters. The correlations were then integrated into the desalination cost evaluation code, DEEP, developed by IAEA and in the course of continued development at CEA. The revised version of the code was then applied to a specific project of nuclear desalination (the TUNDESAL project), currently being carried out in the context of a collaboration agreement between France and Tunisia, under the aegis of the IAEA regional cooperation programme.