Chemical Engineering Job Interview Questions

Frequently asked interview questions for chemical engineering jobs

1)   When to use double pipe heat exchanger and shell and tube heat exchanger?
2)   What is Biot No?
3)   What should be the pressure to be taken for pipe and reactor before put in service?
4)   Which liquid should be on shell side of a shell and tube HE and why?
5)   How we can find leakage in any tube in shell and tube HE?
6)   What is the difference between vapor and gas?
7)   What is the difference between evaporation and boiling?
8)   Why the hot liquid in heat exchanger, reactor jacket should flow from bottom to top?
9)   Why steam enters top side of jacket in reactor?
10) When we need pumps in parallel and pumps in series?
11) When to use gear pumps?
12) Please give a comparison between orifice meter and venturi meter.
13) Why centrifugal pumps are widely used in process industries than positive displacement pumps
14) Give brief classification of handling pumps
15) What is surging in compressors and how it can be prevented?
16) Differentiate compressors, fans and blowers?
17) What is the difference between HAZOP and HAZAN?
18) Why we use LMTD to calculate overall heat transfer co efficient in shell and tube than arithmetic average?
19) What should be the packing size in packed columns?
20) When to use absorption factor method to calculate no of plates?
21) How to convert ppm in to percentage?
22) What is TLV (threshold limit value)?
23) What is critical insulation thickness for pipes?
24) What is priming in centrifugal pumps?
25) Why PD pumps need safety valve at discharge side whereas a centrifugal pump doesn’t need it?
26) Why steam ejectors are located above 10.33 meters only (or) What is Barometric leg ?
27) What is the size of nozzle in steam ejectors?
28) Why Steam ejectors are used in series?
29) What is MSDS?
30) What is the role of casing in centrifugal pumps?
31) What is the difference between PFD and PID?
32) What is the MOC of HE?
33) Why earthing done in reactors?
34) Why SS are not corrosive?
35) When vacuum distillation is needed?
36) What is the use of plate efficiency in distillation column?
37) What would be impact if we increase and decrease the size of packing in packed column?
38) Why tangential entry in cyclone separators?
39) When to use gate valve and globe, ball?
40) When extended surface HE is required?
41) How liquid nitrogen is saved in tanks?
42) In which type of condensation (Film type, drop wise) heat transfer would be higher?
43) What is the use of baffles in heat exchangers?
44) Why baffles are used in reactors?
45) Both the Nusselt number and the Biot number have the same form. What are the differences between them in terms of the variables employed and their physical significance?
46) What are the color codes for cylinders of Oxygen, Carbon di oxide, and Chlorine?
47) Please provide the color coding of pipe lines in process industries.
48) What is the difference between fouling and scaling?
49) What is dry bulb temperature, wet bulb temperature?
50) What is dew point and why it is important in instrument air?
51) What is the difference between Distillation and Fractionation (fractional distillation)?
52) Can Bernaulli's theorem be applied on gases?
53) What is the difference between unit operation and unit process?
54) Why the efficiency of multiple effect evaporator is less then single effect evaporator?
55) Explain the designing of distillation column.
56) What is valency?
57) What is the Law of Thermodynamics?
58) What is pseudo pressure ?
59) What is corrosion? Which is the most important material used for metallic coating?