Keyword: MSF; MSF-OT; MSF-BM; Generalized Disjunctive Programming (GDP); Mixed-Integer Nonlinear Programming (MINLP)
Desalination is the way to produce fresh water from saline water. Industrial desalination of sea water have been developed in order to provide sustainable source of fresh water for worldwide countries. Thermal process were the oldest and most dominating desalination techniques in the world. Multi-Stage Flash (MSF) distillation unit was already used for many years ago and is now the largest sector in the desalination industry.
In this work, a steady state mathematical model of Multistage Flash (MSF) desalination process is developed and validated against the results reported in the literature using GAMS software. The model is then used for further investigation.
First, a steady state mathematical model has been developed above using GAMS modelling tool. The model predictions for both MSF-OT and MSF-BM in steady state conditions showed good agreement against data from existing MSF plants.

Secondly, the superstructure is proposed for the optimization for both Once Through and Brine Mixing process. The mathematical formulation for MSF-OT and MSF-BM was developed using the Generalized Disjunctive Programming (GDP) framework and reformulated into a mixed-integer nonlinear programming (MINLP) problem. The resulting optimization problem was solved using the available state-of-the-art solvers in GAMS software. The objective function is focused on minimizing the total annualized cost (TAC) of MSF-OT and MSF-BM process. Primary results illustrate the capabilities of our approach to offer to the decision-maker the best design depending on the purchased cost of the equipment.