Design of a Multi Stage Flashing (MSF) Desalination Plant in Surman – Libya

Abstract

Thermal water desalination is one of the most important techniques to solve the water scarcity problem in many regions of the world. Out of around 7.8 billion people in the world, only about 6 billion of them have access to clean water: Notably, climate change plays a major role in accelerating the evaporation rate of water from water bodies, which in turn increases the scarcity. Multi-stage flash, recognized to have a high rate of water production in comparison with other available technologies, at accounts for 35% of water desalination facilities worldwide.

In this work, three designs with different number of Stages 22, 26, 29 respectively are presented for the one-off type and another three more with recirculating brine are presented as well. The temperature drop of the brine stream was 2.72 °C/stage, 2.31 °C/stage, 2.07 °C/stage in for three designs respectively. The top brine temperature was 100°C. The results show that 59.5 kg/s for the three designs of the type one time, of superheated steam is required to desalinate 162 kg/s of 1587 kg/s, influent mass flow of brine.

In the three designs with recirculating brine the results show that 24.35 kg/sec, 20.62 kg/sec, and 18.47 kg/sec respectively of superheated steam it is required to desalinate 162 kg/s of 354.375 kg/s of the seawater flowing and 1586 of the flow of recycle brine. The PR ratios were as follows 2.72 for the first three designs and 6.65, 7.85, 8.77 respectively to the recycled brine designs, PR was achieved using the third design, which features a 29-stage brine recycling configuration.