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Steam Boilers, Engines, Nozzles & Turbines MCQ Solved Paper for SBI Clerk

Thursday 9th of March 2023

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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. The process of maintaining the speed of the turbine constant for various load conditions, is known as
A. Bleeding
B. Reheating
C. Governing
D. None of these
Answer : C
3. 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
4. The high pressure boiler is one, which produces steam at a pressure more than
A. Atmospheric pressure
B. 5 kg/cm²
C. 10 kg/cm²
D. 7580 kg/cm²
Answer : D
5. 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
6. The diameter of Cornish boiler varies from
A. 0.5 to 1 m
B. 1 to 2 m
C. 1.25 to 2.5 m
D. 2 to 3 m
Answer : B
7. During storage, the heating value of coal
A. Increases
B. Decreases
C. Remain constant
D. May increase or decrease depending upon the method of storage
Answer : B
8. A boiler in India should conform to safety regulations of
A. DIN
B. BS
C. ASTM
D. IBR
Answer : D
9. The critical pressure ratio for initially superheated steam is __________ as compared to initially dry saturated steam.
A. More
B. Less
C. Same
D. None of these
Answer : B
10. The length of shell of a Locomotive boiler is
A. 1 m
B. 2 m
C. 3 m
D. 4 m
Answer : D
11. The length of Lancashire boiler varies from
A. 5 to 6 m
B. 6 to 7 m
C. 7.25 to 9 m
D. 9 to 10 m
Answer : C
12. The maximum discharge through a chimney occurs when the height of chimney is
A. Infinitely long
B. Around 200 meters
C. Equal to the height of the hot gas column producing draught
D. Outside temperature is very low
Answer : C
13. If partial pressure of air and steam be pa and ps respectively in a condenser, then according to Dalton's law, the pressure in condenser is equal to
A. ps - pa
B. pa - ps
C. pa + ps
D. None of these
Answer : C
14. The capacity of induced draft fan compared to forced draft fan in a boiler is
A. Same
B. More
C. Less
D. Less or more depending on size of boiler
Answer : B
15. Which of the following substance will have same percentage in both proximate and ultimate analysis?
A. Ash
B. Volatile matter
C. Moisture
D. Hydrogen
Answer : A
16. When the cross-section of a nozzle __________ continuously from entrance to exit, it is called a convergent nozzle.
A. Increases
B. Decreases
C. Remain same
D. None of these
Answer : B
17. Which of the following is not a boiler mounting?
A. Blow off cock
B. Feed check valve
C. Economiser
D. Fusible plug
Answer : C
18. 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
19. Expanding steam to a very low pressure (high vacuum) in steam engines is
A. Desirable
B. Economical
C. Essential
D. Uneconomical
Answer : D
20. The main object of a boiler trial is
A. To determine the generating capacity of the boiler
B. To determine the thermal efficiency of the boiler when working at a definite pressure
C. To prepare heat balance sheet for the boiler
D. All of the above
Answer : D
21. The diagram factor is the ratio of the
A. Area of the actual indicator diagram to the area of theoretical indicator diagram
B. Actual workdone per stroke to the theoretical workdone per stroke
C. Actual mean effective pressure to the theoretical mean effective pressure
D. Any one of the above
Answer : D
22. 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
23. A device used in a boiler to control the flow of steam from the boiler to the main pipe and to shut off the steam completely when required, is known as
A. Blow off cock
B. Fusible plug
C. Superheater
D. Stop valve
Answer : D
24. Which is not correct statement about effect of sulphur in fuel?
A. It has heating value
B. It helps in electrostatic precipitation of ash in flue gases
C. It leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low
D. It erodes furnace walls
Answer : D
25. Fusible plug for boilers is made of fusible metal containing tin, lead, and
A. Bismuth
B. Copper
C. Aluminium
D. Nickel
Answer : A
26. In a Parson's turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be
A. 160/3 m/s
B. 320/3 m/s
C. 640/3 m/s
D. 640 m/s
Answer : C
27. 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
28. 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
29. Coke is produced by
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. Enriching carbon in the coal
Answer : C
30. The maximum heat loss is a boiler occurs due to
A. Moisture in fuel
B. Dry flue gases
C. Steam formation
D. Unburnt carbon
Answer : B
31. Willians line for the steam engine is a straight line relationship between the steam consumption per hour and
A. Indicated power
B. Brake power
C. Efficiency
D. Pressure of steam
Answer : A
32. The amount of water evaporated from feed water at _________ into dry and saturated steam at 100° C at normal atmospheric pressure is called equivalent evaporation from and at 100° C.
A. 0°C
B. 40°C
C. 60°C
D. 100°C
Answer : D
33. In regenerative 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 gas from furnace
Answer : B
34. The pressure of reheat steam after passing through reheater compared to inlet condition is
A. More
B. Less
C. Equal
D. May be more or less depending on capacity of reheater
Answer : B
35. In a throttling process
A. Steam temperature remains constant
B. Steam pressure remains constant
C. Steam enthalpy remains constant
D. Steam entropy remains constant
Answer : C
36. In impulse turbines, when friction is neglected, the relative velocity of steam at outlet tip of the blade is __________ the relative velocity of steam at inlet tip of the blade.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : A
37. By compounding the expansion of steam in two or more cylinders, the length of stroke
A. Does not change
B. Increases
C. Decreases
D. None of these
Answer : C
38. Water at pressure of 4 kg/cm² and 160°C temperature when exposed to atmosphere will
A. Boil
B. Flash i.e. get converted into steam
C. Remain as it was
D. Cool down
Answer : B
39. The dry saturated steam at very low pressure, (510 kg/cm²) when throttled to atmosphere will become
A. Wet
B. Superheated
C. Remain dry saturated
D. Dry
Answer : B
40. The friction present between the steam and the nozzle surfaces reduces the heat drop by
A. 10 to 15 %
B. 15 to 25 %
C. 25 to 40 %
D. 40 to 60 %
Answer : A
41. Lancashire boiler is
A. Stationary fire tube boiler
B. Internally fired boiler
C. Horizontal boiler
D. All of these
Answer : D
42. The theoretical indicator diagram of a simple steam engine is based upon the assumption that
A. There is no pressure drop due to condensation
B. Steam is admitted at boiler pressure and exhausted at condenser pressure
C. The expansion (or compression) of the steam is hyperbolic
D. All of the above
Answer : D
43. The ratio of the isentropic heat drop to the heat supplied, is called
A. Reheat factor
B. Stage efficiency
C. Interna efficiency
D. Rankine efficiency
Answer : D
44. The diameter of cylindrical shell of the Lancashire boiler is of the order of
A. 1 to 1.25m
B. 1 to 1.75 m
C. 2 to 4 m
D. 1.75 to 2.75 m.
Answer : D
45. While steam expands in turbines, theoretically the entropy
A. Remains constant
B. Increases
C. Decreases
D. Behaves unpredictably
Answer : A
46. Rateau turbine is
A. Simple reaction turbine
B. Velocity compounded turbine
C. Pressure compounded turbine
D. Pressure-velocity compounded turbine
Answer : C
47. 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
48. The maximum efficiency of a reaction turbine is
A. 2 sin²?/(1 + sin²?)
B. 2 cos²?/(1 + cos²?)
C. (1 + sin²?)/2 sin²?
D. (1 + cos²?)/2 cos²?
Answer : B
49. 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
50. 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
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