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Technical Interview Questions - 6 contains interview questions about  inert gases used in industry, Corrosion and erosion in piping, Saponification, aromatic and aliphatic hydrocarbons, Multiple effect evaporator, single effect, multiple effect evaporator, industrial dryers,

61. What are inert gases? Why they are inert? Give the names of 4 inert gases.
62. Define : Corrosion and erosion
63. Define : Saponification
64. Give difference between aromatic and aliphatic hydrocarbons.
65. Write difference between Forward feed and Backward feed evaporation.
66. Write difference between single effect and multiple effect evaporator.        
67. Name any four dryers along with one application in each
68. Difference between drying and evaporation.
69. Write driving force in Mass transfer operation, Heat transfer operation, Momentum transfer operation.

70. Define Enthalpy.

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61. What are inert gases? Why they are inert? Give the names of 4 inert gases.

  • An inert gas is a gas which does not undergo chemical reactions under a set of given conditions.
  • Inert gases are generally used to avoid unwanted chemical reactions degrading the sample. These undesirable chemical reactions are often oxidation & hydrolysis with oxygen and moisture in air.
  • Examples
    1. Purified ARGON
    2. NITROGEN 
    3. NEON
    4. HELIUM
    5. CO2.

62. Define : Corrosion and erosion

Corrosion
It is natural process in  which  degraded the  useful  property of material  such as strength, structure. It occurs in metal but sometimes in polymer.

Corrosion in pipe


Erosion
It is action of surface process that removes soil, rocks or dissolves  material from the one location to another.

Erosion


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63. Define : Saponification

When an oil or fat is boiled with a solution of caustic  soda, the resultant product are soap and glycerin. The chemical reaction is called saponification.

Oil + NaOH -------- > Soap + Glycerin

64. Give difference between aromatic and aliphatic hydrocarbons.

Aromatic Compound
Aliphatic Compound
They are containing aromatic ring or benzene ring.
They are organic chemical compound without benzene ring.
They are always cyclic.
They are linear and cyclic.
They are always unsaturated.
They are saturated and unsaturated.
They are conjugated due to the presence of alternating double bond.
The majority of aliphatic compound are not conjugated.


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65. Write difference between Forward feed and Backward feed evaporation.


Forward Feed Evaporator
Backward Feed evaporator

Forward feed evaporation


Flow of solution and steam is in parallel direction.

Backward feed evaporation


-Flow of solution and steam is in counter current direction.
-It’s not required pump.
-It’s required pump.
-In this process heating of feed in first effect.
-In this process heating of feed in each effect.
-Maintenance cost and power cost is less.
-Maintenance charge and power cost is high.
-Get less thick liquor.
-Get thick liquor.


66. Write difference between single effect and multiple effect evaporator.

  • In multiple effect evaporator vapour coming out from  1st evaporator  is  use  as feed  for 2nd While in single effect evaporator vapour coming out from evaporator  is  going to condenser and discard.
  • Cost of multiple effect evaporator is higher than single effect
  • Multiple effect evaporator is use in large scale
single effect evaporator
single effect evaporator

multiple effect evaporator
multiple effect evaporator


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67. Name any four dryers along with one application in each

Tray Dryer

Used in dyes and pharmaceuticals

Tray Dryer

Tray Dryer cross section


Spray Dryer

Used in detergent and food

Spray dryer




Fluidized Bed Dryer (FBD)

Used in pharmaceuticals

Fluidized Bed Dryer (FBD)
Fluidized Bed Dryer (FBD)


Fluidized Bed Dryer (FBD) cross section
Fluidized Bed Dryer (FBD) cross section


Rotary Dryer

Used in Cement industry


Rotary Dryer working



Roto Cone Vacuum Dryer (RCVD)
Used in Pharmaceuticals

Roto Cone Vacuum Dryer(RCVD)
Roto Cone Vacuum Dryer(RCVD)
Roto Cone Vacuum Dryer(RCVD) cross section
Roto Cone Vacuum Dryer(RCVD) cross section

68. Difference between drying and evaporation.

DRYING
EVAPORATION
-Small amount of solvent removed.
-Large amount of solvent removed.
-Remove solvent below boiling point.
-Remove solvent at boiling point.
-Main purpose to get dried product
-Main purpose to increasing concentration of product.

69. Write driving force in Mass transfer operation, Heat transfer operation, Momentum transfer operation.
  • Mass transfer operation: – Transfer of mass from higher concentration to lower
  • Heat transfer operation: – Transfer of heat from higher temperature to lower
  • Momentum transfer operation: – Transfer of fluid from higher velocity to lower
  • Momentum  – Mass × Velocity
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70. Define Enthalpy.

Enthalpy is defined as thermodynamic state function denoted by letter “H”, that consists of internal energy system (U) plus product Pressure (P) & Volume(V) of the system.
H = U + pV

Unit - Joule, Calories

Thanks for reading - Technical Interview Questions - 6
Naitik Patel
Industrial Guide

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