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Desalination
Published in Frank R. Spellman, Hydraulic Fracturing Wastewater, 2017
Often used for seawater desalination, multiple-effect distillation (MED) consists of multiple “effects,” or stages in series. In each effect, the feed water is heated by steam in tubes. Vapor from the first effect is condensed in the second effect, and the heat of condensation is used to evaporate the water in the second effect. Each effect is connected in series and essentially reuses the energy from the previous effect. Thus, this system is a low energy consumer compared to other thermal processes. MED has the advantages of simple operation and low maintenance costs.
Desalination
Published in Sarah Bell, Urban Water Sustainability, 2017
The first major improvement in the efficiency of desalination was the development of multi-effect distillation (MED). MED was initially developed for sugar refining, and it uses a series of connected evaporation cells, each at a lower temperature than the previous one. In each cell, seawater is sprayed over a pipe containing steam, causing water to condense within the pipe. The seawater evaporates in the cell, producing steam that is transferred into the next chamber in a closed pipe, where it condenses due to the lower temperature (Figure 9.1).
The Game Changers
Published in Anco S. Blazev, Energy Security for The 21st Century, 2021
Other innovations include “capacitive deionization,” which does away with separate membranes and uses porous electrodes that both attract and trap salt. Another is “multiple-effect distillation,” which produces water vapor and leaves salt behind at 30 percent greater energy efficiency over the conventional methods.
Low-grade heat from solar ponds: trends, perspectives, and prospects
Published in International Journal of Ambient Energy, 2022
Farbod Esmaeilion, Abolfazl Ahmadi, Mehdi Aliehyaei
By considering the performance possibilities of the solar pond for reaching the process of over 100°C, solar pond potential for producing freshwater from seawater has been investigated. Providing some chained circumstances like steady temperature through the year, condensation process at low temperature, and suitable heat transfer are effective. Based on obtained results for desalinating seawater, producing each cubic metre of seawater needs 1000–4000 m2 surface of solar pond per day (Salata and Coppi 2014; Esmaeilion 2020). In the titanium desalination system, a solar pond is utilised to prevent chemical corrosion with the help of salty water (Caruso and Naviglio 1999). By announcing a new construction consisted of the solar pond, membrane distillation, and multiple effect distillation, contaminated water purified and freshwater produced (Lu, Walton, and Swift2001).
Effects of Film Flow and a Surfactant on Scale Formation in Falling Film Evaporators for Seawater Desalination
Published in Heat Transfer Engineering, 2022
Maximilian Waack, Heike Glade, Stephan Nied
Falling film flow and scale formation are crucial aspects to be considered during the design and operation of horizontal tube falling film evaporators, which are commonly used in multiple-effect distillation (MED) plants for seawater desalination. Seawater is distributed onto the upper tube rows of a horizontal tube bundle by spray nozzles. The liquid forms a thin film on the outside of the tubes and trickles down tube by tube. On the one hand, a thin seawater film on the outside of the tubes is favorable with regard to a high heat transfer coefficient. On the other hand, lowering the liquid load increases the risk of film breakdown which may accelerate the precipitation of inversely soluble salts on the heat transfer surface and lowers the effective heat transfer area. Moreover, the initial seawater distribution onto the top of the tube bundle is prone to failure due to clogging of the commonly used spray nozzles which gives rise to an uneven liquid distribution within the tube bundle and accelerated crystallization fouling.
The water–energy nexus: energy use for water supply in China
Published in International Journal of Water Resources Development, 2019
Guohua He, Yong Zhao, Jianhua Wang, Haihong Li, Yongnan Zhu, Shang Jiang
Reverse osmosis and low-temperature multiple-effect distillation are the two major desalination technologies currently used in China, with 80.3% and 14.5% of the desalination plants employing these methods , respectively ( State Oceanic Administration of China, 2015). Zheng, Chen, Wang, and Zhang (2014) estimated the average energy requirements in China for desalination of seawater using reverse osmosis (5 kWh/m3) and low-temperature multiple-effect distillation (8 kWh/m3). Therefore, in this study, the weighted average value of 6.5 kWh/m3 was used as the energy requirement for desalination.