Multi-effect water distiller Working principle: The qualified raw water is input into the preheater after increased the pressure by multilevel pump. After heat exchanging, the raw water is entered into each preheater. Next the raw water is input into the raw water distributor of the 1st stage evaporator, which is spouted to the inside of the heating tubes. So that the raw water in the tube is flowed as membrane, which is heated by boiler steam. The produced second steam with drips is entered into the gas and steam separating setting from the bottom of the heating tubes. The separated pure steam is entered into the next stage as heating steam, meanwhile, the raw water, which is not evaporated, entered into the next stage. And then it is repeated above mentioned process. The pure steam from last stage is converged with each stages condensed water(except 1st stages), after cooling and drainage of the infusible gas, it is became the WFI with the temperature 92-99 Centigrade. How to guarantee high quality of WFI? Double tubesheet:Avoiding cross pollution by some materials.(It is customized to choose single tube or double tubesheet, according to customers requirements)