Distributor plate and evaporator

A method of operating an evaporator system having a plurality of effects, each of said effects including:

• a header chamber for receiving liquid to be concentrated by evaporation;
• a callandria adapted to provide evaporation of liquid from a falling film in inner surfaces of the callandria;
• and
• a distributor plate located in the header chamber to distribute liquid to openings of the callandria via distribution holes in the distributor plate, said distributor plate including an essential planar plate member perforated with said distribution holes and further including a series of overflow conduits for providing a rapid flow of a washing liquid through the plate during washing, the conduits having inlets disposed above the surface of the planar plate, said method including:
• feeding the liquid to be evaporated into the effects in series, said effects being retained under vacuum to facilitate evaporation;
• maintaining a level on said distributor plates of the liquid to be evaporated at less than the height of inlets of the overflow conduits above the respective plates;
• returning the effects to ambient pressure;
• and providing parallel feeding of wash liquid into the header chambers of the effects and onto respective distributor plates at such a rate as to produce overflow of wash liquid into the inlets of the overflow conduits.