Types of Distillation & column internals

More:- https://chemicalengineeringworld.com
Distillation is a method of separating the components of a solution which depends upon distribution of the substances between a gas and liquid phase, applied to cases where all components are present in both phases.
* What is distillation ?
* Types of Distillation
* Batch Distillation
* Azeotropic Distillation
* Flooding
* Priming
* Coning
* Weeping
* Dumping
* Packed Column
* Tray column
* Reflux Ratio
* Relative volatility
* Distillation column
Distillation is a method of separating mixtures based on differences in volatility (volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure.) of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction

1. Distillation Index 1) What is distillation? 2) Comparison of Distillation with other Mass transfer operation 3 ) Reflux ratio, Relative volatility 4) Problems in distillation 5)Types of Distillation 6) Packed tower and tray tower https://chemicalengineeringworld.com

2. 1) What is distillation? Distillation is a method of separating the components of a solution which depends upon distribution of the substances between a gas and liquid phase, applied to cases where all components are present in both phases. Distillation  is a method of  separating   mixtures  based on differences in   volatilities ( volatility  is the tendency of a substance to  vaporize . Volatility is directly related to a substance's  vapor pressure .)  of components in a boiling liquid mixture. Distillation is a unit operation , or a physical separation process, and not a  chemical reaction . https://chemicalengineeringworld.com

3. Distillation column Reboiler Residue Condenser Distillate Reflux Feed https://chemicalengineeringworld.com

4. In Distillation vapor rising in the section above the feed (called the absorption, enriching, or rectifying section) is washed with liquid to remove or absorb the less volatile component. The liquid returned to the top of the tower is called reflux and the material permanently removed is the distillate. The section below the feed (stripping or exhausting section) the liquid is stripped of volatile component by vapor produced in reboiler . https://chemicalengineeringworld.com

5. Difference between Distillation and other MTO Distillation > foreign substance is not required. > So there is no choice required for selection of new substance . > Give pure product, Further purification is not required. https://chemicalengineeringworld.com

6. Other MTO > foreign substance required. > So there is choice required for selection of new substance . > Not give pure product, Further purification is required. https://chemicalengineeringworld.com

7. Important parameters for Distillation Relative volatility Reflux Reflux ratio https://chemicalengineeringworld.com

8. Relative volatility It is the ratio of concentration ratio of one component to other in one phase to other phase. Relative volatility is usually denoted as α. It indicates the ease or difficulty of using distillation to separate the more  volatile  components from the less volatile components in a mixture For separation,it should be greater than 1. https://chemicalengineeringworld.com

9. Reflux Ratio Reflux = Liquid return to column/ Distillate Minimum Reflux ratio ,Maximum Reflux ratio , Optimum reflux ratio Increasing reflux ratio Improves separation Increases cycle time Increases energy consumption https://chemicalengineeringworld.com

10. Types of Distillation 1) Single stage operation (Flash Vaporization ) 2) Batch Distillation 3) Azeotropic Distillation 4) Extractive Distillation https://chemicalengineeringworld.com

11. Single stage operation- Flash vaporization Here the liquid mixture is partially vaporized, the vapor allowed to come to equilibrium with the residual liquid and the resulting liquid and vapor phase separated from the apparatus. vapor liquid separator Feed https://chemicalengineeringworld.com

12. Batch Distillation The oldest operation used for separation of liquid mixtures . Feed is fed from bottom, where includes R e-boiler, to be processed . Numbers of accumulator tanks are connected to collect the main and the intermediate distillate fractions. https://chemicalengineeringworld.com

13. Azeotropic Distillation What is Azeotrope ? It is constant Boiling mixture. Azeotropic distillation  usually refers to the specific technique of adding another component to generate a new, lower-boiling azeotrope , such as the example below with the addition of benzene to water and ethanol. https://chemicalengineeringworld.com

14. Extractive Distillation The method of extractive distillation uses a separation solvent, which is generally nonvolatile, has a high boiling point and is miscible with the mixture, but doesn't form an azeotropic mixture. Third component change the relative volatility of the mixture. A classic example to be cited here is the separation of an azeotropic mixture of  benzene  and  cyclohexane , where  aniline  is one suitable solvent. https://chemicalengineeringworld.com

15. Problems in tray towers For high tray efficiency we require deep pools of liquid and relatively high gas velocities. These conditions however lead to a number of difficulties. One is the mechanical entrainment in which small droplets of liquid will be carried by the gas to the tray above. Great depth of liquid and high gas velocities both result in high pressure drop for the gas in flowing through the tray. In absorber and humidifiers high pressure drop result in high fan power to blow the gas to the tower which result in high operating cost. In distillation high pressure at the bottom of the tower results in high boiling temperatures, which in turn may lead to heating difficulties and possibly damaged to heat sensitive compounds. https://chemicalengineeringworld.com

16. Flooding Entrainment Priming Coning Weeping Dumping https://chemicalengineeringworld.com

17. https://chemicalengineeringworld.com

18. Flooding As the pressure difference is increased due to increased rate of flow of either gas or liquid the level in the downspout will rise further to permit the liquid to enter the lower tray. And finally the liquid level may reach that on the tray above. Further increased in any rate, liquid will fill the entire space between the trays. The tower is then flooded. Liquid may be forced out of the exit pipe of the tower. https://chemicalengineeringworld.com

19. Priming For liquid gas combinations which tend to foam excessively, high gas velocities lead to condition of priming. Here the foam persists throughout the space between trays and a great deal of liquid is carried by the gas from one tray to the tray above. https://chemicalengineeringworld.com

20. Coning If liquid rate are too low, the gas rising through the openings of the tray may push the liquid away and the contact of the gas and the liquid is poor. That is called coning. https://chemicalengineeringworld.com

21. Weeping If the gas rate is too low, much of the liquid may rain down through the openings of the tray. Its called weeping. Dumping And at very low gas rates, none of the liquid reaches the downspouts. Its called dumping. https://chemicalengineeringworld.com

22. Packed Column In industry, a  packed column  is a type of packed bed used to perform  separation processes , such as  absorption ,  stripping , and  distillation . A packed column is a  pressure vessel  that has a packed section https://chemicalengineeringworld.com

23. Tray column https://chemicalengineeringworld.com

24. https://chemicalengineeringworld.com

25. https://chemicalengineeringworld.com

26. https://chemicalengineeringworld.com

27. https://chemicalengineeringworld.com

28. https://chemicalengineeringworld.com

29. https://chemicalengineeringworld.com

30. Tray Column v/s Packed Column Tray tower Tray is used Cleaning is Easy. Dirty service (plate columns are easier to clean) Pressure drop is high Side stream withdrawal is possible. Presence of thermal or mechanical stress due to large temperature changes which might lead to cracked packings https://chemicalengineeringworld.com

31. Packed Column Packing used in packed column Side stream withdrawal is not possible. Cleaning is Difficult. More choices in materials of construction for packings especially in corrosive service (e.g. plastic, ceramic, metal alloys) lower pressure drop (important in vacuum distillation) less liquid entrainment · low liquid hold-up, especially suitable for thermally sensitive material https://chemicalengineeringworld.com

32. Thank You https://chemicalengineeringworld.com