Evaporators are essential pieces of equipment for most processes. They are a specialized configuration of a shell and tube heat exchanger. The shell and tube types that we build can generally be categorized as either falling film or forced circulation.
In a falling film type the process liquid is preheated to nearly boiling temperature before being evenly distributed by a distribution tray or splash plate to the tubes. As gravity pulls the liquid down through the tubes, heat transferred from the shell side boils some of the film. The vapor and remaining liquid are collected and routed counter-flow through several other evaporators called evaporation effects to create the desired product concentration.
Forced circulation types are preferred with process liquors which are susceptible to scaling or crystallizing. As the liquid is circulated through the heat exchanger tubes, boiling is prevented by keeping the pressure just above the boiling point. As the liquor enters the lower pressure separator, the liquid flashes to vapor.