FLASH DISTILLATION

FLASH DISTILLATION

Distillation is a process of separating the component substances from a liquid mixture by selective evaporation and condensation.

                   

Ex: Distilled water is water that has many of its impurities removed                       through distillation

          Vodka is made by the distillation of fermented substances such as                     grains, potatoes, or sometimes fruits or sugar.

FLASH means sudden occurrence of something.

DEFINITION: Flash distillation is defined as a process in which the entire liquid mixture is suddenly vaporized(flash) by passing the feed from a high pressure zone to a low pressure zone.

also called as equilibrium distillation.

PRINCIPLE:

• —  When hot liquid is passed from high pressure zone to low pressure zone     the entire liquid is suddenly vaporized.
•   This is called as flash vaporization.
•  —  During this process chamber gets cooled because of vapors.
•  —  The molecules which have low boiling point remains as vapour.
•  —  The molecules which have high boiling point gets condensed.
•   Due to this low boiling point molecules the entire system gets cooled.
•   This process requires certain amount of time. So liquid and vapour is kept   in intimate contact until equilibrium is achieved.
•  The liquid is collected separately. The vapour is separated from the liquid  and again allowed to condense.

          

CONSTRUCTION:
   —  It consists of :

•     Feed Reservoir
•     Pump
•     Heater
•     Pressure Reducing Valve
•     Vapour Separator

WORKING:

•   When the feed is pumped into the heater which is having high pressure.    The feed gets heated.
• — This feed enters into vapour separator by passing through pressure  reducing valve.
• — Then pressure of liquid is reduced and liquid gets vaporised.
• — Due to vapours the equipment gets cooled.
• — Due to cooling the molecules which have high boiling point get condensed  and forms as liquid.
• — And some remains as vapours which are having low boiling point.
• — This mixture is allowed for sufficient time. so, vapour and liquid portions    separate and achieve equilibrium.
• — At the top of vapour separator vapour is separated and at the bottom  liquid is separated.
• — By continuous feed, flash distillation is obtained continuously.
• — Amount of feed is exactly equal to amount of  material removed.
• — Therefore vapour and liquid concentrations at any point remains constant    in the unit.

         

USES:

• —       It is used for separating components which are having different boiling       points.
• —  It is widely used in petroleum industry for refining crude oil.

ADVANTAGES:

• —  It is continuous process.
• —  It is used for obtaining multi-component systems of narrow boiling range,   especially in oil refinery.

              Eg:- petroleum 60,80 etc.,

DISADVANTAGES:

• —  It is not effective in separating components of comparable volatility.
• —  It is not suitable for two component system.