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Technical Interview Questions - 7 contains following interview questions about Unit operation, Unit process, Pressure test, catalysts are used in Chlorination and Hydrogenation, Ton of refrigeration in Chiller, Ton of refrigeration cooling water.

71. Define : Unit operation, Unit process
72. What is difference between Bubble point & Boiling Point? What is difference between Dew point and freezing point?
73. What is Avogadro number? What is its importance?
74. What is Pressure test?
75. Which gas occupied maxi

71. Define : Unit operation, Unit process

Unit Operation

When any physical change takes place it is Unit operation.
Change in Concentration from inlet to outlet

Example: Distillation, Filtration, Drying, Extraction, Gas absorption, Crystallization

Unit Process

When any physical change takes place it is Unit operation.
Example: - Oxidation, Reduction, Alkylation, Sulphonation, Chlorination, etc.

72. What is difference between Bubble point & Boiling Point? What is difference between Dew point and freezing point?

Bubble point : It is temperature at which first bubble of liquid is formed.

Boiling Point : It is a temperature of liquid at which vapour pressure of liquid is equal to atmospheric pressure [1 atm, 1.03323 Kg/cm²].

Explanation:

We have 2 chemicals mixture.

1. Less volatile chemical
2. High Volatile chemical
Volatility of fluid : Capability of liquid to convert into vaporize.
When initial phase of boiling starts less volatile chemical starts to vaporize.
At last high volatile chemical starts vaporizing.

Dew point : When any chemicals temperature is dropping, Whole vapour phase starts converting to liquid phase. At certain temperature there will no traces of chemical in vapour phase. This is dew point of Chemical.

Freezing point: When any liquid is converted into solid phase at 1 Atmospheric pressure. This temperature is Freezing point of fluid.

73. What is Avogadro number? What is its importance?

Numbers of molecules present in 1 mole.

Value : 6.023 * 10²³ / mole

74. What is Pressure test?

Pressure test is carried When any new Piping system or Pressure vessel is installed 

For Piping system it should be capable to hold double pressure then maximum operating pressure for certain time.

For vessels and reactors it should be handle up to 1.5 times of maximum pressure for certain temperature.

If piping system is designed to 10 kg/cm² then pressure test should be carried to 20 kg/cm² [Some times this is carried on 15 kg/cm² it not recommended]

Reactor and vessel designed to 10 kg/cm² then pressure test should be carried to 15 kg/cm²

75. Which gas occupied maxim




 

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