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Technical Interview Questions -3 contains questions asked in Chemical Pharma Petrochemical technical interview

31. What is surging in compressors and how it can be prevented?
32. Distinguish between latent heat & sensible heat.
33. What is crystallization? Give Name of crystallizers.
34. Why Earthing is provided in Solvent line?
35. What is ISO & kaizen?
36. Write the name of strong and

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31. What is surging in compressors and how it can be prevented?

In centrifugal and axial compressors when the suction volume falls below a certain limit i.e. when the compressor is not getting enough volume of gas to compress, the gas from discharge side will flow back to the compressor( which would reduce the speed of compressor )and join together with the suction side to increase the volume input.

Thereafter the speed of compressor picks and it come to normal operation. But meanwhile such revere in flow will cross huge pressure gradient across the compressor and vibration thus may damage the impeller. This momentary reverse flow lapses for very short time

To prevent surging we need to install an anti-surging system. The anti-surging system shall have a mechanism to measure the suction flow and discharge flow time to time along with a control valve. When the suction volume falls below a certain set value a part of discharge gas will be directed towards the suction to maintain the minimum suction volume.

As normally compression leads to increase in temperature the gas recycle sis taken after the “after cooler” to ensure the discharge temperature is within control.

32. Distinguish between latent heat & sensible heat.

Latent heat

Latent heat is the enthalpy change associated with temperature change of a body along with phase change.

Sensible heat 

The enthalpy change associated with temperature change of a body in the same phase.

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33. What is crystallization? Give Name of crystallizers.

Crystallization

It is the unit operation in which purification and producing  the  crystal from liquid mixture.

Name of crystallizers

  • Vacuum crystallizer
  • Agitated tank crystallizer
  • Swenson-walker crystallizer
  • Draft tube crystallizer

34. What is ISO & kaizen?

ISO

ISO (International Organization for standardization) is an international standards- setting body composed of representatives from various national standards organizations.

Kaizen

It is Japanese word that refers to activities that continuously improve all functions & involve all employees from the CEO to the assembly line workers.

35. Write the name of 



 

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