Power Plant Engineering

81. The maximum length of a screw conveyer is about

1. 30 metres
2. 40 metres
3. 60 metres
4. 100 metres

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82. The maximum percentage gain in Regenerative feed heating cycle thermal efficiency

1. increases with number of feed heaters increasing
2. decreases with number of feed heaters increasing
3. remains same unaffected by number of feed heaters
4. none of the above

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83. The modern steam turbines are

1. impulse turbines
2. reaction turbines
3. impulse-reaction turbines
4. none of the above

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84. The overall efficiency of thermal power plant is equal to

1. Rankine cycle efficiency
2. Carnot cycle efficiency
3. Regenerative cycle efficiency
4. Boiler efficiency x turbine efficiency x generator efficiency

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85. The percentage 02 by volume in atmosphere air is

1. 21%
2. 23%
3. 77%
4. 79%

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86. The percentage O2 by Weight in atmospheric air is

1. 18%
2. 23%
3. 77%
4. 79%

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87. The pressure at the furnace is minimum in case of

1. forced draught system
2. induced draught system
3. balanced draught system
4. natural draught system

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88. The pressure on the two sides of the impulse wheel of a steam turbine

1. is same
2. is different
3. increases from one side to the other side
4. decreases from one side to the other side

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89. The proper indication of incomplete combustion is

1. high CO content in flue gases at exit
2. high CO2 content in flue gases at exit
3. high temperature of flue gases
4. the smoking exhaust from chimney

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

1. 0.6
2. 0.578
3. 0.555
4. 0.5457

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