Principle and technical characteristics of reverse osmosis desalination Desalination consists of a high-pressure pump, a pressure vessel and an energy recovery unit. After seawater is pre-treated and pressurized by the high-pressure pump and sent into the pressure vessel of the reverse osmosis unit, the seawater first passes through the first membrane element and flows in the inlet spacer net channel of the spiral coiling of this membrane element, and under the higher pressure, a part of the water molecules continuously penetrate through the membrane and enter into the central tube of the coiling membrane element through the water-producing spacer net flow channel to produce the product water, and the rest of the inlet water continues to flow along the direction of the water flow to the next membrane element. This process is carried out sequentially, when the feed water through the next membrane element, the concentration of feed water increases, flow through the last membrane element, the feed water becomes concentrated water, concentrated water flow out of the pressure vessel after the energy recovery device to recover the remaining pressure energy and then excluded.