SAIL chemical engineering questions with answers
1. Which of the following chemicals is used for dosing boiler drum to reduce dissolve gases ?
c) Hydrazine (Ans)
2. The total dissolve solids (TDS) after water treatment through a water softener plant
c) remains same (Ans)
d) may increase or decrease
3. The insulation thickness for which the total cost is minimum is called
a) economic thickness of insulation (Ans)
b) minimum insulation thickness
c) maximum insulation thickness
d) cheapest insulation thickness
4. Which of the following does not contribute to efficient to use of steam ?
a) Superheated steam for indirect process heating (Ans)
b) Insulation of steam pipelines
c) Providing dry steam for process
d) Reducing work to be done by steam
5. Which among the following steam turbines has the maximum efficiency ?
a) condensing turbine (Ans)
b) Extraction condensing turbine
c) Back pressure turbine
d) Double extraction condensing turbine
6. The equipment having the highest efficiency in case of conventional power plant is
a) electric generator (Ans)
c) gas turbine
d) cooling tower
7. The equipment used to remove dirt from steam lines installed before steam trap is
a) bypass line
b) drain valve
c) strain (Ans)
d) vent valve
8. Which type of steam is ideal for indirect heat transfer in a heat exchanger?
a) Wet steam
b) Dry saturated steam (Ans)
c) Superheated steam
d) none of these
9. Recovery of heat from dryer exhaust air is a typical application of
a) heat pump
b) heat pipe
c) heat wheel (Ans)
d) heat exchanger (double pipe type)
10. Which of the following co-generation system has maximum heat to power ratio ?
a) Reciprocating engine
b) Gas turbine
c) Back pressure steam turbine (Ans)
d) Combined cycle
11. Which is the best location for measuring CO2 & O2% in flue gases for combustion efficiency in a thermal power plant ?
a) After the economiser
b) Outlet of the boiler (Ans)
c) Bottom of the Chimney
d) Before the economiser
12. If an equipment’s steam consumption is 2 tons/hr, then what should be the steam trap capacity in tons/hr?
c) 3 (Ans)
13. The device used to upgrade a lower pressure steam to a higher pressure steam is called
a) jet ejector
b) heat pump
c) thermocompressor (Ans)
d) heat wheel
14. Steam generation in a boiler is 26 tons in 2 hours. Fuel consumption in the same period is 1 ton/hr. Continuous blowdown is 10% of feed water input. The evaporation ratio is
c) 13 (Ans)
15. If the voltage level of distribution system is raised from 11kV to 22 kV for the same loading condition, the distribution losses are reduced by —-per cent.
c) 25 (Ans)
16. A 230 V single phase line supplies to a load of 25 amperes at 0.80 power factor. The active power supplied by the line will be
a) 4.6 kW (Ans)
b) 4.6 kVA
c) 7.96 kW
d) 7.96 MVA
17. If the gross heat rate of a thermal power plant is given, then the efficiency is equal to the ——-of gross heat rate.
a) inverse (Ans)
c) square root
d) cube root
18. The rating of the capacitor at motor terminals should not be more than the magnetizing kVAR of the motor at ——load.
c) no (Ans)
19. A screw compressor belongs to the positive displacement compressor type. The other name for the screw compressor is the ——-compressor.
c) helical axial
d) helical rotary (Ans)
20. Which compressor best meets the high volume low pressure requirements?
a) Reciprocating compressor
b) Centrifugal compressor (Ans)
c) Lobe compressor
d) Rotary compressor
21. Which of the following can also act as a heat pump ?
a) Air conditioner (Ans)
b) Reciprocating compressor
c) Centrifugal compressor
d) none of these
22. A three phase induction motor loaded at less than 50% , if operated in star mode will reult in
a) electrical downsizing of the motor
b) improved efficiency & power factor
c) reduced operating voltage
d) all a, b & c (Ans)
23. The driving force for refrigeration vapor absorption refrigeration system is ——-energy
c) thermal (Ans)
d) both a&b
24. What loading percentage can be ideally considered as a meaningful figure to decide on the best motor efficiency in the selection process ?
c) 75 (Ans)
25. An eight pole induction motor operating at 50 Hz will have a synchronous speed of —– rpm.
a) 750 (Ans)
26. In a double pipe heat exchanger the I.D and O.D. of the inner pipe are 4cm & 5cms respectively. The I.D. of the outer pipe is 10cm with a wall thickness of 1cm. Then the equivalent diameters (in cm) of the annulus of heat transfer and pressure drop respectively are
a) 15, 5 (Ans)
b) 21, 6
c) 6, 19
d) 15, 21
27. Hydraulic mean diameter for flow through packed bed of spherical particles of size Dp with porosity ε is
28. The sphericity of a cylinder of 1 mm diameter and length 3 mm is
a) 0.90 (Ans)
29. When an unsaturated air-water vapor mixture is heated at constant pressure, then the
a) partial pressure of water vapor increases
b) specific humidity decreases
c) relative humidity increases
d) relative humidity decreases (Ans)
30. Two iron pipes of the same nominal diameter but different schedule numbers will have the same
a) inside diameter (Ans)
b) outside diameter
c) wall thickness
d) none of the above