Technoeconomic analysis of once through long tube MSF process for high capacity desalination plants

•Barriers of increasing MSF evaporator capacity are solved.•Five tube bundles, once through, and long tubes are the key components of process efficiency.•Significant saving in the water tariff cost.•Novel layout of MSF evaporator is proposed to reduce footprint up to 60%.

This work presents a technoeconomic comparison between once through long tube (MSF-OT-LT) with atmospheric deaerator, and brine recycle cross tube (MSF-BR-CT) evaporators. The process design and cost analysis of 30 MIGD MSF-OT-LT evaporator is presented.The process calculations showed that for the same performance ratio, the heat transfer area of MSF-OT-LT is 34% lower than that of MSF-BR evaporator. This is due to the flashing range increase and higher heat transfer coefficient of MSF-OT-LT configuration. The pumping power of the MSF-OT-LT is 40% lower than that of MSF-BR-CT evaporator. This is due to lower friction loss in the tubes and due to remove brine recycle pump. A novel configuration of MSF-OT-LT is proposed in which the stages are arranged in a triple deck. The footprint decreases up to 57% in the large size project of 150 MIGD.For a large size project of 150 MIGD capacity, the unit water cost of the MSF-OT-LT configuration is 36% lower than that of the MSF-BR-CT. It can be concluded from this study that the MSF-OT-LT evaporator is a viable option for large scale capacity and a reliable technology for poor quality and high salinity sea water.