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Distillation interview questions

Distillation interview questions blog contains interview questions regarding to distillation process and concept

  1. What is normal tray spacing (Distance between two plates) in distillation column?
  2. What are the various graphical methods for the calculation of number of plates in distillation column?
  3. What are the different types of tray efficiencies?
  4. What is relative volatility of fluids? How it impact distillation?
  5. Distinguish between liquid-liquid extraction and leaching?
  6. State operational problems in distillation column


Question 1: What is normal tray spacing (Distance between two plates) in distillation column?

Answer: As per thumb rule. Normal tray spacing is 2 ft. or 0.6m. Height should not exceed 30m. Hence maximum numbers of try is about 50 trays due to fabrication limit diameter of column should be less than 7m and height less than 35meter.

                       
Distillation interview questions Tray spacing

Question 2: What are the various graphical methods for the calculation of number of plates in distillation column?

Answer: There are three methods

  1. Mccabe thiele method
  2. Ponchon sevrit method
  3. Lewis sorel method


Question 3: What are the different types of tray efficiencies?

Answer: There are three types of tray efficiencies
  1. Local or point efficiencies
  2. Murphee plate efficiencies
  3. Overall efficiency
In most of cases overall plate efficiencies is used which is founded by

Overall plate efficiency = No of ideal trays required / No of actual trays required

Question 4: What is relative volatility of fluids? How it impact distillation?

Answer: The relative volatility is the ratio of the K values for two components. It is denoted by ‘α’
               
                                α = k1 /k2

In distillation if relative volatility is high then it is easy to separate fluid mixture and few numbers of trays required but if relative volatility is near 1 then it’s difficult to distillate fluid mixture.

Relative volatility is reduced if column pressure is increased.

Question 5: Distinguish between liquid-liquid extraction and leaching?

Answer: In liquid-liquid extraction solvent is used as solvent to separate liquids and in leaching (also known as solid-liquid extraction) solute is using to separate like separate oil from oil cake using hexane.

Question 6: State operational problems in distillation column

Answer: Mainly there are four problems occurring
  1. Flooding
  2. Weeping/Dumping
  3. Entrainment
  4. Foaming

In Packed bed column there are main three problems
  1. Channeling
  2. Loading
  3. Flooding



 

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