Steam Boilers, Engines, Nozzles & Turbines 1000+ MCQ with answer for NMAT

1. Which of the following statement is wrong?
A. The critical pressure gives the velocity of steam at the throat equal to the velocity of sound.
B. The flow in the convergent portion of the nozzle is subsonic.
C. The flow in the divergent portion of the nozzle is supersonic.
D. To increase the velocity of steam above sonic velocity (supersonic) by expanding steam below the critical pressure, the divergent portion for the nozzle is not necessary.
Answer : D

2. Expansion ratio is the ratio of
A. Swept volume to the volume at cut-off
B. Clearance volume to the swept volume
C. Volume at cut-off to the swept volume
D. Swept volume to the clearance volume
Answer : A

3. The ratio of heat equivalent to brake power to the energy supplied in steam is known as
A. Mechanical efficiency
B. Overall efficiency
C. Indicated thermal efficiency
D. Brake thermal efficiency
Answer : D

4. Curtis turbine is a
A. Simple reaction turbine
B. Velocity compounded turbine
C. Pressure compounded turbine
D. Pressure-velocity compounded turbine
Answer : D

5. At critical point, i.e. p = 225.65 kg/cm², the latent enthalpy of vaporisation is
A. Maximum
B. Minimum
C. Zero
D. Depends on temperature also
Answer : C

6. The ratio of the workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam is called
A. Blading efficiency
B. Nozzle efficiency
C. Stage efficiency
D. Mechanical efficiency
Answer : C

7. The velocity of flue gases (V) through the chimney under a static draught of (H') metres is given by
A. V = 2g H'
B. V = 2g/H'
C. V = H'/2g
D. V = 2gH'
Answer : A

8. The Locomotive boiler has
A. 137 fire tubes and 44 superheated tubes
B. 147 fire tubes and 34 superheated tubes
C. 157 fire tubes and 24 superheated tubes
D. 167 fire tubes and 14 superheated tubes
Answer : C

9. Boiler H.P. is defined as the
A. Steam evaporation rate per kg of fuel fired
B. Work done in evaporating 1 kg of steam per hour from and at 100°C into dry saturated steam
C. The evaporation of 15.65 kg of water per hour from and at 100°C into dry saturated steam
D. Work done by 1 kg of steam at saturation condition
Answer : C

10. Evaporative capacity of boiler is expressed as
A. kg of steam produced
B. Steam pressure produced
C. kg of fuel fired
D. kg of steam produced per kg of fuel fifed
Answer : D

11. Fire tube boilers are
A. Internally fired
B. Externally fired
C. Internally as well as externally fired
D. None of these
Answer : A

12. A stage, in reaction turbine, is represented by
A. Number of casing
B. Number of entries of steam
C. Number of exits of steam
D. Each row of blades
Answer : D

13. Superheating of steam is done at
A. Constant volume
B. Constant temperature
C. Constant pressure
D. Constant entropy
Answer : C

14. In a reaction turbine, when steam flows through the moving blades,
A. Pressure increases while velocity decreases
B. Pressure decreases while velocity increases
C. Pressure and velocity both decreases
D. Pressure and velocity both increases
Answer : C

15. The draught (in mm of water), for maximum discharge of flue gases through the chimney, is given by (where H = Height of the chimney in metres, and T₁ = Absolute temperature of air outside the chimney in K)
A. T₁ /88.25H
B. 88.25H/T₁
C. T₁ /176.5H
D. 176.5H/T₁
Answer : D

16. The fire tubes in, a Coarran and Scottish marine boiler are
A. Horizontal
B. Vertical
C. Inclined
D. Both horizontal and vertical
Answer : A

17. Pick up the correct statement as regards Cornish boiler and Lancashire boiler
A. Cornish is fire tube and Lancashire is water tube
B. Cornish is water tube and Lancashire is fire tube
C. Cornish has two fire tubes and Lancashire has one
D. Lancashire has two fire tubes and Cornish has one
Answer : D

18. In water wall furnace, the heat is transferred to the water walls by
A. Convection
B. Radiation
C. Conduction
D. Radiation and conduction
Answer : B

19. A safety valve in a locomotive starts leaking. The leaking medium will be
A. Water
B. Dry steam
C. Wet steam
D. Super heated steam
Answer : D

20. Latent heat of dry steam at atmospheric pressure is equal to
A. 539 kcal/ kg
B. 539 BTU/ lb
C. 427 kcal/ kg
D. 100 kcal/ kg
Answer : A

21. Hard coke is produced by carburisation of coal at
A. Atmospheric temperature
B. 500-600°C
C. 700-850°C
D. 950-1100°C
Answer : D

22. Bomb calorimeter is used to determine
A. Higher calorific value at constant volume
B. Lower calorific value at constant volume
C. Higher calorific value at constant pressure
D. Lower calorific value at constant pressure
Answer : A

23. The critical pressure ratio is given by (where p? = Initial pressure of steam, and p? = Pressure of steam at throat or critical pressure)
A. p?. p?
B. p?/p?
C. p?/p?
D. p? + p?
Answer : C

24. The major axis of elliptical manholes on the shell should be provided
A. Longitudinally
B. Circumferentially
C. On dished end
D. Anywhere
Answer : B

25. In a nozzle, whole frictional loss is assumed to occur between
A. Inlet and throat
B. Inlet and outlet
C. Throat and exit
D. All of these
Answer : C

26. A steam turbine, in which a part of the steam after partial expansion, is used for process heating and the remaining steam is further expanded for power generation, is known as
A. Back pressure turbine
B. Pass out turbine
C. Low pressure turbine
D. Impulse turbine
Answer : B

27. The reheat factor is the ratio of the
A. Cumulative heat drop to the isentropic heat drop
B. Isentropic heat drop to the heat supplied
C. Total useful heat drop to the total isentropic heat drop
D. None of the above
Answer : A

28. The object of producing draught in a boiler is
A. To provide an adequate supply of air for the fuel combustion
B. To exhaust the gases of combustion from the combustion chamber
C. To discharge the gases of combustion to the atmosphere through the chimney
D. All of the above
Answer : D

29. Which of the following statement is correct for a compound steam engine?
A. The cost of the engine, for the same power and economy, is more than that of a simple steam engine.
B. The forces in the working parts are increased as the forces are distributed over more parts.
C. The ratio of expansion is reduced, thus reducing the length of stroke.
D. The temperature range per cylinder is increased, with corresponding increase in condensation.
Answer : C

30. In case of condensing steam engines, the pressure of steam in the cylinder during exhaust stroke is _________ the atmospheric pressure.
A. Equal to
B. Lower than
C. Higher than
D. None of these
Answer : C

31. A fusible plug is fitted in small boilers in order to
A. Avoid excessive build up of pressure
B. Avoid explosion
C. Extinguish fire if water level in the boiler falls below alarming limit
D. Control steam dome
Answer : C

32. Proximate analysis of fuel is determination of percentage of
A. Carbon, hydrogen, nitrogen, sulphur, moisture
B. Fixed carbon, ash, volatile matter, moisture
C. Higher calorific value
D. Lower calorific value
Answer : B

33. Pick up the wrong statement about critical condition of steam
A. Latent heat is zero
B. Liquid directly becomes steam
C. Specific volume of steam and liquid is same
D. This is the maximum pressure limit
Answer : D

34. Which of the following statement indicates the difference between Cornish boiler and Lancashire boiler?
A. Cornish boiler is a water tube boiler whereas Lancashire boiler is a fire tube boiler
B. Cornish boiler is a fire tube boiler whereas Lancashire boiler is a water tube boiler
C. Cornish boiler has one flue tube whereas Lancashire boiler has two flue tubes
D. Cornish boiler has two flue tubes whereas Lancashire boiler has one flue tube
Answer : C

35. The economiser is used in boilers to
A. Increase thermal efficiency of boiler
B. Economise on fuel
C. Extract heat from the exhaust flue gases
D. Increase flue gas temperature
Answer : A

36. The effect of friction in the nozzle __________ dryness fraction of steam.
A. Has no effect on
B. Decreases
C. Increases
D. None of these
Answer : C

37. The condition of steam in boiler drum is always
A. Dry
B. Wet
C. Saturated
D. Supersaturated
Answer : B

38. The high pressure and low pressure cylinders in a Woolf type compound engine are regarded as having cranks
A. 180° to each other
B. 90° to each other
C. 0° to each other
D. None of these
Answer : A

39. The critical pressure at which latent heat of vaporisation is zero is
A. 225.65 kgf/ cm²
B. 273 kgf/ cm²
C. 100 kgf/ cm²
D. 1 kgf/ cm²
Answer : A

40. The actual vacuum in a condenser is equal to
A. Barometric pressure + actual pressure
B. Barometric pressure - actual pressure
C. Gauge pressure + atmospheric pressure
D. Gauge pressure - atmospheric pressure
Answer : B

41. The length of Cornish boiler varies from
A. 2 to 4.5 m
B. 3 to 5 m
C. 5 to 7.5 m
D. 7 to 9 m
Answer : C

42. A device used to heat feed water by utilising the heat in me exhaust flue gases before leaving through the chimney, is known as
A. Economiser
B. Fusible plug
C. Superheater
D. Stop valve
Answer : A

43. When the total heat of steam is h kJ/kg and the sensible heat of feed water is h_f1 kJ/kg, then the factor of evaporation is given by
A. (h - h_f1)/2257
B. (h + h_f1)/2257
C. (h × h_f1)/2257
D. None of these
Answer : A

44. The basic job of feed water treatment in boilers is to overcome the problem of
A. Corrosion
B. Scale
C. Carryover
D. All of the above
Answer : D

45. On Mollier chart, flow through turbine is represented by
A. Horizontal straight line
B. Vertical straight line
C. Straight inclined line
D. Curved line
Answer : B

46. 100% efficiency of a thermal cycle cannot be achieved because of
A. Frictional losses
B. It is not possible to achieve 0°K temperature
C. Leakage
D. Non availability of ideal substance
Answer : B

47. A steam nozzle converts
A. Heat energy of steam into kinetic energy
B. Kinetic energy into heat energy of steam
C. Heat energy of steam into potential energy
D. Potential energy into heat energy of steam
Answer : A

48. An air preheater is installed
A. Before the economiser
B. Before the superheater
C. Between the economiser and chimney
D. None of these
Answer : C

49. The water tubes in a simple vertical boiler are
A. Horizontal
B. Vertical
C. Inclined
D. None of these
Answer : C

50. Carbonisation of coal is the process of
A. Pulverising coal in inert atmosphere
B. Heating wood in a limited supply of air at temperatures below 300°C
C. Strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
D. Binding the pulverised coal into briquettes
Answer : C