NOVELTY - Rotary heat supply type sea water desalting comprises (i) providing a sea water desalting device, and (ii) using the sea water desalting device for desalting seawater. The seawater desalting device comprises a vacuum pump (1), a sea water pump (2), a sea water pre-heating chamber (3), and a vacuum evaporation chamber (4). The sea water pre-heating chamber is provided with a rotating shaft, a mechanical seal disposed between the rotating shaft and sea water pre-heating chamber, a sea water preheating cavity located inside the sea water pre-heating chamber.    USE - The method is useful for rotary heat supply type sea water desalting (claimed).    ADVANTAGE - The method utilizes self-generated steam and friction medium heat to provide energy for sea water desalting; does not utilize chemical agent; is environmentally friendly; and can be driven by electric energy or utilizes renewable energy source, preferably wind energy, hydro energy, tidal energy, and other renewable mechanical energy to drive directly or indirectly.    DETAILED DESCRIPTION - Rotary heat supply type sea water desalting comprises (i) providing a sea water desalting device, and (ii) using the sea water desalting device for desalting seawater. The seawater desalting device comprises a vacuum pump (1), a sea water pump (2), a sea water pre-heating chamber (3), and a vacuum evaporation chamber (4). The sea water pre-heating chamber is provided with a rotating shaft, a mechanical seal is disposed between the rotating shaft and sea water pre-heating chamber, a sea water preheating cavity is located inside the sea water pre-heating chamber, and surrounds the rotating shaft. The sea water pre-heating chamber is fixedly connected with the static disc provided with a non-condensable gas outlet. The static disc is provided with the overflow weir, where the overflow weir and the sea water pre-heating cavity are matched to form fresh water overflow port. The sea water pre-heating cavity at the bottom part is set with a friction heater, and the upper part with a rotating shell. The pipe coil opens to the outside through the steam inlet. The rotating shell is clamped between the sealing cover. The sealing cover is connected with the steam inlet and a mechanical seal. The sea water preheating cavity is fixed on the static disc. A hollow cylindrical baffle plate is set on the rotating shell and the steam baffle plate and a sea water pipe coil. The sea water coil pipe each layer is provided with a horizontal annular baffle plate. The baffle plate is fixed on the rotary shell and the steam baffle plate. The water pipe is respectively connected with cooling seawater inlet and the hot water outlet set on the sea water pre-heating cavity on the outer edge end of the guiding sheet. The sea water pre-heating chamber shell upper part is set with steam inlet and air inlet. The steam inlet and the sea water pre-heating chamber is set between the static seal. The sea water pre-heating chamber shell side is set with a fresh water outlet, which is connected with the guide plate, and is respectively set on the sea water pre-heating chamber. The sea water pre-heating cavity at the bottom is provided with a drain outlet. The vacuum evaporating chamber is set with rotating shaft. A mechanical seal is between the rotating shaft and the vacuum chamber. The fresh water groove is located in the vacuum chamber, and surrounds the rotating shaft. The vacuum evaporating chamber is fixedly connected with the static disc provided with the overflow weir. The overflow weir and the water groove form fresh water overflow port. The water groove at the bottom is set with a liquid distributor. The water groove is fixed at the center with a central column, and provided with a hollow cylindrical liquid blocking plate near the inner edge. The liquid distribution plate is horizontal mounted on the central column and the liquid blocking plate. The rotating shaft is set on the upper part of the outlet water tank, which is provided with a waste outlet port. The outlet water tank is provided with multiple water discharging holes, and is provided with a drain valve. The drain hole is provided with guide plate. The outlet water tank through the water leakage hole is connected with the water groove. The drain hole is set on the water groove and the central column and the liquid blocking plate. The vacuum evaporating chamber is provided with a hot sea water inlet. An atomizer is connected with the hot sea water inlet. The vacuum evaporating chamber is set between the static seal. The vacuum evaporating chamber shell side part is set with a concentrated sea water outlet. The concentrated sea water outlet connected to the guide plate, and passes through the static disc. The vacuum chamber is provided with a vapor outlet. The bottom of vacuum evaporating chamber is provided with a drain outlet.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the sea water desalting device (Drawing includes non-English language text).    Vacuum pump (1)    Sea water pump (2)    Sea water pre-heating chamber (3)    Vacuum evaporation chamber (4)