Power Plant Engineering Mcq Questions Pdf

41. Compounding of steam turbines is done in order to

(a) reduce the rotor speed.
(b) increase the rotor speed.
(c) balance the turbine.
(d) none of the above.

42. The governing employed for medium and larger sized steam tur-bines is

(a) bypass.
(b) nozzle.
(c) throttle.
(d) combination of (b) and (c).

43. The ratio of exit pressure to inlet pressure of maximum mass flow rate per unit area of steam through a nozzle, when the steam is initially super heated, is

(a) 0.65
(b) 0.578
(c) 0.5457
(d) 0.5325

44. The ratio of exit pressure to inlet pressure of maximum mass flow rate per unit area of steam through a nozzle, when the steam is initially dry saturated, is

(a) 0.5325
(b) 0.5457
(c) 0.578
(d) 0.65

45. The effect of considering friction in steam nozzles for the same pressure ratio leads to

(a) increase in dryness fraction of exit steam.
(b) decrease in exit velocity from the nozzle.
(c) no change in exit velocity from the nozzle and quality of exit steam.
(d) both (a) and (b).

46. The steam is superheated to the highest economical temperature in order to

(a) reduce the requirement of steam for a given output of energy owing to its high internal energy and thus reduce the turbine size.
(b) reduce the mechanical resistance to the flow of steam over turbine blades and increase the efficiency as superheated steam is dry and so turbine blades remain dry.
(c) avoid corrosion and pitting at the turbine blades occurring owing to steam dryness.
(d) all of the above.

47. Any leakage of air into the condenser destroys the vacuum and causes

(a) an increase in air pressure in the condenser limiting the useful heat drop in the steam turbine.
(b) lowering of the partial pressure of the steam and of the saturation temperature along with it.
(c) under-cooling of the condensate more severe.
(d) all of the above.

48. A 200 MW steam power plant will consume nearly………..tonnes of coal per day.

(a) 1,000
(b) 2,000
(c) 4,000
(d) 7,500

49. Heating value of coal is roughly

(a) 1,000 – 1,500 kcal/kg
(b) 3,000 – 4,500 kcal/kg
(c) 5,000 – 6,500 kcal/kg
(d) 7,500 – 10,000 kcal/kg

50. Calorific value of coal largely depends upon

(a) ash content.
(b) size of coal particles.
(c) moisture content.
(d) volatile matter.

51. The coal of the lowest calorific value is

(a) anthracite.
(b) bituminous coal.
(c) lignite.
(d) steam coal.

52. The coal having highest calorific value is

(a) anthracite.
(b) bituminous.
(c) lignite.
(d) peat

53. Coal used in thermal power plants is also known as

(a) soft coal
(b) steam coal.
(c) charcoal.
(d) coke.

54. Coking cokes

(a) do not form ash.
(b) burn completely.
(c) form lumps or masses of coke.
(d) burn freely.

55. Which of the following is considered to be superior quality of coal ?

(a) Bituminous.
(b) Coke.
(c) Lignite.
(d) Peat

56. Low grade coals have

(a) low carbon content.
(b) low calorific value.
(c) low moisture content.
(d) low ash content.

57. Coal is usually considered of

(a) lava origin.
(b) animal origin.
(c) vegetable origin.
(d) none of the above.

58. Coal rank classifies coal as per its

(a) specific gravity.
(b) degree of metamorphism.
(c) carbon percentage.
(d) ash content.

59. The average ash content in Indian coals is around

(a) 5%.
(b) 10%.
(c) 20%.
(d) 30%.

60. The coal that has highest ash content is

(a) lignite.
(b) coking coal.
(c) bituminous coal.
(d) steam coal.