Optimisation of MSF Desalination Process for Fixed Water Demand using gPROMS

Simultaneous optimisation of design and operating parameters of MSF desalination process is considered here using MINLP technique within gPROMS software. For a fixed fresh water demand throughout the year and with seasonal variation of seawater temperature, the external heat input (a measure of operating cost) to the process is minimised. It is observed that seasonal variation in seawater temperature results in significant variation in design with minimum variation in operating conditions in terms of process temperatures. The results also reveal the possibility of designing stand-alone flash stages which would offer flexible scheduling in terms of the connection of various units (to build up the process) and efficient maintenance of the units throughout the year as the weather condition changes. In addition, operation at low temperatures throughout the year will reduce design and operating costs in terms of low temperature materials of construction and reduced amount of antiscaling and anti-corrosion agents.