Parametric Optimization of Multi-Stage Flashing Desalination System Using Genetic Algorithm for Efficient Energy Utilization

The technique of multi-stage desalination with brine recirculation (MSF-BR) is characterized by its high energy demand, necessitating the exploration of efficient operational methods to minimize energy consumption and enhance plant performance. In this research study, Matlab R2021a software was used to apply a genetic algorithm with the aim of determining the optimal values of the operating variables of the MSF-BR system within certain limits, considering energy consumption and feed seawater temperature variation. The study included improving several operational factors, including top brine temperature, steam temperature, feed seawater temperature, cooling water flow rate and make up flow rate, number of station stages, and the stages of the heat rejection section. The optimal maintenance period during the operational year was also determined. The results of the analysis were based on data from the Al-Khafji desalination plant, which consists of 16 stages and has a production capacity of 7,053,393.8 gallons/day. The study aimed to achieve two main objectives: increasing the gain output ratio (GOR) and reducing the proportion of the recovery ratio. The results showed that the optimal period for maintenance is January, where the performance ratio ranges between 0.987 and 9.38, compared to the currently used month of December, where the performance ratio ranges between 1.096 and 9.56. Optimal target values were set at the following operating parameters: 33.3 °C for feed seawater temperature, 98.67 °C for steam temperature, 95.62 °C for brine temperature, 1571.18 kg/s for cooling water flow rate, 1624.24 kg/s for feed water flow rate, 21 stages for the station, and two stages for the heat rejection section. To achieve the highest GOR, the number of stages and heat rejection section should be more than 19 and 2, respectively. In general, to achieve improvements in GOR and reduce energy consumption, it is recommended to maintain Tf in the range of 33–34 °C and set Mcw between 1050 and 1800 kg/s.