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Renin Angiotensin Mechanism.

Evaporators: Evaporating Still.

 

Definition:

  • The equipment used for carrying out the process of evaporation are called “Evaporators”.

  • Evaporators are classified according to the form of the heat movement,

    • Natural circulation evaporators. e.g Evaporating Pan.

    • Forced circulation evaporation. e.g. Modified evaporating pan.

    • Film evaporators. e.g Climbing film evaporator.

Evaporating Still:

Construction:

  • It consists of a jacketed-evaporating pan with a cylindrical cover that connects it to a condenser. 

  • The overall assembly is called still. 

  • The cover is clamped with the evaporating pan. 

Working:

  • The dilute liquid is fed into the still, the cover is clamped. 

  • Steam is introduced into the jacket. 

  • The liquid is evaporated and condensed in the condenser and collected. 

  • The product (i.e. concentrated liquid) is collected through the product outlet.

Advantages:

  1. Simple construction and easy to clean and maintain.

  2. The vapor is removed by condensation which 

    1. speeds evaporation

    2. reduces inconvenience and allows the equipment to be used for solvents other than water e.g. ethanol.

  3. A receiver and vacuum pump can be fitted to the condenser, permitting operation under reduced pressure and, hence, at lower temperature.

Disadvantages:

  • Natural convection only

  • All the liquor is heated all the time

  • The heating surface is limited.

Uses:

  1. Aqueous and other  solvents may be evaporated

  2. Thermolabile materials can be evaporated under reduced pressure.

  3. Removing the still head is convenient for evaporating extracts to dryness.

Commonly Asked Questions.

  1. Define evaporation and write a short note on “Evaporating Still”.
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