Reboiler

An evaporator is in process technology, an apparatus for converting a liquid into its vapor state. Industrially variety of evaporators are used. For example, the Robert evaporator in the sugar industry, or thin film evaporator for the evaporation of food concentrates or pharmaceutical solutions. To reduce costs, it is common to connect several evaporators in series. For this purpose, the first evaporator with heating steam (possibly with pressure ) heated. The following evaporators are heated with the vapors generated ( = solvent vapor ) from the previous evaporator. From the first to the last evaporator must gradually the pressure be lowered in order to gain energy from the vapors.

Principle

For evaporation of the liquid, the supply of thermal energy is required. Therefore evaporators are usually from a surface through which heat from a heating medium is transferred to the liquid to be evaporated. With direct evaporators, in contrast, the heating medium can be placed directly in contact with the liquid. The heating medium may consist of a hot liquid cooled or from a vapor which is condensed, exist.

The physical basis

For evaporation of a liquid occurs when the vapor pressure exceeds the prevailing pressure. In this case, the pressure may be different from the ambient pressure, i.e., higher or lower. The vapor pressure in turn depends on the temperature and increases with this. To evaporate the liquid, energy is needed, which corresponds to the enthalpy of evaporation. The same amount of energy is released when the vapor formed is condensed again.

When a liquid into an inert, overcurrent forming gas, such as air evaporates, it is called evaporation. The energy for evaporation originates from the liquid and the air itself, so that cooling takes place.

Evaporator types

There are different types of evaporators. The most common types are:

• Steam boiler
• Thin-film evaporator
• Falling film evaporator
• Kettle- type evaporator
• Koaxialverdampfer
• Natural circulation evaporator
• Forced circulation evaporator

• Heat exchanger
• Steam boiler technology