61. Thermal efficiency of a thermal power plant is of the order of___________________?
A. 15%
B. 20%
C. 30%
D. 45%
E. 60%.

62. Pick up wrong statement about desired properties of a good fuel__________________?
A. high calorific value
B. produce minimum smoke and gases
C. ease in storing
D. high ignition point
E. economical

63. Which is not correct statement about pulverized fuel firing ?
A. high burning rate is possible
B. heat release can be easily controlled
C. fuel burns economically
D. it is the best technique for burning high ash content fuel having low fusion ash
E. separate mills are required to powder the coal

64. Which is not correct statement about the function of furnace____________________?
A. to provide proper conditions for con-tinuous complete combustion
B. mix fuel with air and ignite
C. separate ash from coal
D. maintain heat supply to prepare and ignite the incoming fuel
E. to minimise radiation losses

65. Which is not the correct statement about moisture in coal ______________________?
A. inherent moisture and surface mois┬Čture are different things
B. in some coals moisture may be present upto 40%
C. some moisture in coal helps in better burning which is not possible with completely dry coal
D. it increases thermal efficiency
E. moisture in coal is removed before firing by heating it with hot air

66. 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
E. none of the above

67. 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
E. more than the tallest building nearby

68. In locomotives, the draught is produced by_________________?
A. chimney
B. induced draft fan
C. both combined A. and B.
D. steam jet draught
E. none of the above

69. Vacuum for reciprocating steam engines compared to steam turbines is__________________?
A. more
B. equal
C. less
D. could be more or less depending on the size of plant
E. none of the above

70. The height of chimney in a power plant is governed by__________________?
A. the draft to be created
B. limitation of construction facilities
C. control of pollution
D. quantity of flue gases to be handled
E. all of the above

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