Evaporator and its affecting factors

EVAPORATOR

An evaporator is a device in a process used to turn the liquid form of a chemical substance such as water into its gaseous-form/vapor. The liquid is evaporated, or vaporized, into a gas form of the targeted substance in that process. The process of evaporation is used widely in the chemical and process industry, and for a variety of purposes. These include the concentration of solutions (often as a precursor to crystallization of the solute), revaporization of liquefied gases, refrigeration applications (cooling or chilling), and generation of pure and mixed vapors for process applications. The term evaporators is usually reserved vapors for the first of these applications, namely the evaporation of the solvent from a solution in order to concentrate the solution. Evaporators may be classified into falling film evaporators (in which evaporation takes place from the film interface with no nucleate boiling at the wall), nucleate boiling evaporators (in which wall nucleate boiling occurs over part or all of the heat transfer surface), flash evaporators and direct contact evaporators. Some evaporators are used to concentrate a solution by vapourizing and eliminating water, as, for example, in a concentration plant for sugar and syrup. In purification processes, such as the desalination of seawater, evaporators convert the water to vapour, leaving mineral residues in the evaporator. The vapour then is condensed into (desalinated) water. In a refrigerationsystem, the cooling effect is produced as the rapid evaporation of the liquid refrigerant absorbs heat.