Evaporators are used to increase the vapor pressure

Evaporators are typically used to remove water from most liquid streams. Typically, heat is added to the pumping loop and a large vapor/liquid chamber is used to separate the two fluids. A vacuum can be used to help with this glitter, but is not required. Steam from one stage can be used to boost steam by connecting units together in series so that steam from one stage can be used in a subsequent (lower pressure) stage (multi-effect) or by compressors (mechanical recompression) or steam injection (thermal recompression) pressure and allow reuse at the same stage. Typically, multiple effect evaporators behave as flash systems and are controlled by the VLE.

Compared with the evaporator, the concept of heat exchanger is broader, because "heat exchanger" includes all "heat exchanger equipment" for the purpose of heat exchange, such as radiation heat exchanger, convection heat exchanger, Plate heat exchanger, needle heat exchanger, heat pipe heat exchanger, spoiler heat exchanger, regenerative heat exchanger, gas-liquid heat exchanger, etc.