Desalination temperature difference

Is it true that the former refers to the multi-effect evaporation process, while the latter refers to the low-temperature multi-effect evaporation process?

Personally, I think the former statement is correct.

I think it is the first type. All the documents I have read are written according to the first type. LZ, you can upload the literature with the second theory, and we can share it. :lol

Several main processes of seawater desalination Time: 2009-10-24 Source: Chengdu Kaiyuan Fluid Control Engineering Co., Ltd. Editor: Dai Fulin Seawater desalination (also known as seawater desalination) is the process of separating salt and water in seawater. Desalination can be achieved by removing water from seawater or removing salt from seawater. Seawater desalination methods are basically divided into these two categories. 　　Among them, reverse osmosis, electrodialysis and distillation have been widely used commercially. ①Reverse osmosis (RO) is driven by pressure. Fresh water in seawater enters the low-pressure side of the membrane through a semipermeable membrane, while other components in seawater (such as salt) are blocked on the high-pressure side of the membrane and discharged with concentrated seawater, thereby achieving effective separation. When seawater is desalinated, if an external pressure greater than the osmotic pressure of seawater is applied on one side of the seawater, the pure water in the seawater will reversely penetrate into the freshwater. This is the principle of reverse osmosis seawater desalination (Figure 1). In order to obtain the necessary desalination rate, the actual operating pressure is greater than 5.5MPa. Figure 1 Reverse osmosis desalination process ② Electrodialysis (ED) Under the action of a DC electric field, ions migrate through a selective ion exchange membrane, thereby partially separating electrolyte ions from the solution. This process is called electrodialysis (Figure 2). Figure 2 Electro-osmosis desalination process ③ Distillation method The principle of seawater desalination by distillation method is simple, that is, heating seawater, and obtaining fresh water after the water vapor condenses. Distillation methods are divided into multi-stage flash distillation (MSF), low-temperature multiple effect distillation (MED) and vapor compression distillation (Vaporcom-pression, VC) according to the energy, equipment and processes used. Among them, low-temperature multi-effect operates below 70°C, which is much lower than the steam temperature of around 110°C in multi-stage flash evaporation. It effectively avoids the scaling of inorganic salts and is currently one of the most applicable evaporation technologies. At the same time, it can use various forms of low-level heat sources, such as combining with thermal power plants or nuclear power plants, and using the back pressure of the steam turbine of 0.02 to 0.04MPa (absolute pressure) to pump air and produce water, reducing power generation losses and improving the efficiency of the generator set (Figure 3). Figure 3 MED process flow using steam turbine back pressure steam