Steam Boilers, Engines, Nozzles & Turbines MCQ Solved Paper for ISRO Recruitment

1. The fire tubes in a Locomotive boiler has _________ diameter.
A. 4.75 mm
B. 5.47 mm
C. 7.45 mm
D. 47.5 mm
Answer : D

2. Which of the following gases has the highest calorific value?
A. Producer gas
B. Coal gas
C. Water gas
D. Blast furnace gas
Answer : B

3. The critical pressure ratio (p?/p?) is given by
A. (p?/p?) = [2/(n - 1)] ^{n/(n + 1)}
B. (p?/p?) = [2/(n + 1)] ^n/(n-1)
C. (p?/p?) = [(n - 1)/2] ^{n + (1/n)}
D. (p?/p?) = [(n + 1)/2] ^{n - (1/n)}
Answer : B

4. The pressure of feed water has to be raised before its entry into the boiler. The pressure is raised by a device known as
A. Feed pump
B. Injector
C. Feed check valve
D. Pressure gauge
Answer : A

5. The cylinder condensation or missing quantity may be reduced by
A. The efficient steam jacketing of the cylinder walls
B. Superheating the steam supplied to the engine cylinder
C. Keeping the expansion ratio small in each cylinder
D. All of the above
Answer : D

6. The draught may be produced by a
A. Mechanical fan
B. Chimney
C. A steam jet
D. All of these
Answer : D

7. Heating of dry steam above saturation temperature is known as
A. Enthalpy
B. Superheating
C. Super saturation
D. Latent heat
Answer : B

8. 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

9. 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

10. 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

11. Gradually increasing temperature of flue gases at inlet to chimney for given steam outputs is an indication of
A. Higher effectiveness of boiler
B. High calorific value coal being burnt
C. Fouling of heat transfer surfaces
D. Raising of steam temperature
Answer : C

12. Parson's reaction turbine is a __________ reaction turbine.
A. 40 percent
B. 50 percent
C. 60 percent
D. 70 percent
Answer : B

13. Which of the following statement is correct?
A. Lancashire boiler is a fire tube boiler.
B. Fire tube boilers are internally fired.
C. Babcock and Wilcox boiler is a water tube boiler.
D. All of the above
Answer : D

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

15. Steam engine operates on
A. Carnot cycle
B. Joule cycle
C. Stirling cycle
D. Brayton cycle
Answer : D

16. A condenser in a steam power plant
A. Increases expansion ratio of steam
B. Reduces back pressure of steam
C. Reduces temperature of exhaust steam
D. All of these
Answer : D

17. Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler
A. Increases
B. Decreases
C. Remain unaffected
D. First increases and then decreases
Answer : B

18. Boiler stays are used to
A. Prevent flat surfaces under pressure from tearing apart
B. Take care of failure in shear
C. Take care of failure in compression
D. Provide support for boiler
Answer : A

19. In a uniflow engine
A. Steam enters and exhausts through the same port
B. Steam enters at one end and exhausts at the centre
C. Steam enters at the centre and exhausts at the other end
D. None of the above
Answer : B

20. The maximum discharge of steam through a convergent-divergent nozzle depends upon
A. Area of nozzle at throat
B. Initial pressure and volume of steam
C. Final pressure of steam leaving the nozzle
D. Both (A) and (B)
Answer : D

21. Which of the following statement is correct?
A. A horizontal steam engine requires less floor area than a vertical steam engine
B. The steam pressure in the cylinder is not allowed to fall below the atmospheric pressure
C. The compound steam engines are generally non-condensing steam engines
D. All of the above
Answer : B

22. When the circulation of water, in a boiler, is by convection currents which are set up during the heating of water, then the boiler is known as
A. Internally fired boiler
B. Externally fired boiler
C. Natural circulation boiler
D. Forced circulation boiler
Answer : C

23. The reheat factor depends upon
A. Initial pressure and superheat
B. Exit pressure
C. Turbine stage efficiency
D. All of these
Answer : D

24. Lancashire boiler has __________ internal flue tubes.
A. One
B. Two
C. Three
D. Four
Answer : B

25. A supercritical boiler is one that operates above the pressure and temperature of following values
A. 100 kg/cm² and 540°C
B. 1 kg/cm² and 100°C
C. 218 kg/cm² abs and 373°C
D. 218 kg/cm² abs and 540°C
Answer : C

26. Thermal equilibrium means that the flow of steam is
A. Isothermal
B. Isentropic
C. Hyperbolic
D. Polytropic
Answer : B

27. Which of the following boiler is best suited to meet the fluctuating demand of steam?
A. Locomotive boiler
B. Lancashire boiler
C. Cornish boiler
D. Babcock and Wilcox boiler
Answer : A

28. The overall efficiency of thermal power plant is
A. Boiler efficiency, turbine efficiency, generator efficiency
B. All the three above plus gas cycle efficiency
C. Carnot cycle efficiency
D. Regenerative cycle efficiency
Answer : A

29. Fire tube boilers are those in which
A. Flue gases pass through tubes and water around it
B. Water passes through the tubes and flue gases around it
C. Forced circulation takes place
D. Tubes are laid vertically
Answer : A

30. An air preheater
A. Increases evaporative capacity of the boiler
B. Increases the efficiency of the boiler
C. Enables low grade fuel to be burnt
D. All of the above
Answer : D

31. 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

32. A device used to increase the temperature of saturated steam without raising its pressure, is called
A. Blow off cock
B. Fusible plug
C. Superheater
D. Stop valve
Answer : C

33. 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

34. For a Parson's reaction turbine, if ?? and ?? are fixed blade angles at inlet and exit respectively and ?? and ?? are the moving blade angles at entrance and exit respectively, then
A. ?? = ?? and ?? = ??
B. ?? = ?? and ??= ??
C. ?? < ?? and ?? > ??
D. ?? = ?? and ?? = ??
Answer : B

35. In recuperative air preheaters, the heat is transferred
A. From a metal wall from one medium to another
B. From heating an intermediate material and then heating the air from this material
C. By direct mixing,
D. Heat is transferred by bleeding some gases from furnace
Answer : A

36. 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

37. The basic purpose of drum in boiler is to
A. Serve as storage of steam
B. Serve as storage of feed water for water wall
C. Remove salts from water
D. Separate steam from water
Answer : D

38. A single stage impulse turbine with a diameter of 1.2 m runs at 3000 r.p.m. If the blade speed ratio is 0.42, then the inlet velocity of steam will be
A. 79 m/s
B. 188 m/s
C. 450 m/s
D. 900 m/s
Answer : C

39. When the inlet pressure of steam is equal to the exit pressure, then
A. There is a pressure drop in the nozzle
B. Fluid flows through the nozzle
C. Pressure drops and fluid flows through the nozzle
D. There is no pressure drop and fluid does not flow through the nozzle
Answer : D

40. Reheating of steam under ideal conditions takes place at constant
A. Entropy
B. Enthalpy
C. Pressure
D. Temperature
Answer : D

41. 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

42. 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

43. The length of Cornish boiler is of the order of
A. 24 m
B. 35 m
C. 57.5 m
D. 79 m
Answer : C

44. In a 50% reaction turbine stage, tangential component of absolute velocity at rotor inlet is 537 m/s and the blade velocity is 454 m/s. The power output in kW of steam will be
A. 260 kW
B. 282 kW
C. 296 kW
D. 302 kW
Answer : B

45. Boiler parameters are expressed by
A. Tonnes/hr. of steam
B. Pressure of steam in kg/cm²
C. Temperature of steam in °C
D. All of the above
Answer : D

46. The radius of a dished head is taken approximately as
A. One fourth
B. Half
C. One
D. Two
Answer : C

47. A turbine is said to have an axial discharge when the steam leaves the blade tip at _________ to the direction of the blade motion.
A. 60°
B. 90°
C. 180°
D. 270°
Answer : B

48. If partial pressure of air and steam be p_a and p_s respectively in a condenser, then according to Dalton's law, the pressure in condenser is equal to
A. p_s - p_a
B. p_a - p_s
C. p_a + p_s
D. None of these
Answer : C

49. Cochran boiler is a
A. Horizontal fire tube boiler
B. Horizontal water tube boiler
C. Vertical water tube boiler
D. Vertical fire tube boiler
Answer : D

50. In a velocity compounded impulse turbine, when steam flows through the second row of moving blades,
A. Velocity increases
B. Velocity decreases
C. Velocity remains constant
D. Pressure remains constant
Answer : B