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Fractionation at total reflux. The Fenske equation in continuous fractional distillation is an equation used for calculating the minimum number of theoretical plates required for the separation of a binary feed stream by a fractionation column that is being operated at total reflux (i.e., which means that no overhead product distillate is being withdrawn from the column).
The McCabe–Thiele method is a technique that is commonly employed in the field of chemical engineering to model the separation of two substances by a distillation column. [1] [2] [3] It uses the fact that the composition at each theoretical tray is completely determined by the mole fraction of one of the two components.
In a typical fractional distillation, a liquid mixture is heated in the distilling flask, and the resulting vapor rises up the fractionating column (see Figure 1). The vapor condenses on glass spurs (known as theoretical trays or theoretical plates) inside the column, and returns to the distilling flask, refluxing the rising distillate vapor ...
There is a very important distinction between the theoretical plate terminology used in discussing conventional distillation trays and the theoretical plate terminology used in the discussions below of packed bed distillation or absorption or in chromatography or other applications.
Typical industrial fractional distillation columns. Fractional distillation is the most common form of separation technology used in petroleum refineries, petrochemical and chemical plants, natural gas processing and cryogenic air separation plants. [3] [4] In most cases, the distillation is operated at a continuous steady state. New feed is ...
Key fractional distillation concepts: theoretical stages, x-y diagrams, multicomponent distillation, column composition and temperature profiles; Process design and optimization: minimum reflux and minimum stages, optimum reflux, short-cut methods, feed entry location
The reflux system in a typical industrial distillation column. Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial [1] and laboratory [2] distillations. It is also used in chemistry to supply energy to reactions over a long period of time.
Moreover, the efficiencies of the vapor–liquid contact devices (referred to as "plates" or "trays") used in distillation towers are typically lower than that of a theoretical 100% efficient equilibrium stage. Hence, a distillation tower needs more trays than the number of theoretical vapor–liquid equilibrium stages.