Steam Boilers Engines Nozzles and Turbines

101. Size of boiler tubes is specified by

1. mean diameter and thickness
2. inside diameter and thickness
3. outside diameter and thickness
4. outside diameter and inside diameter
5. outside diameter alone.

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102. Spontaneous combustion is a phenomenon in which

1. all the fuel burns instantaneously producing high energy release
2. fuel burns with less air
3. coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
4. explosion in furnace
5. none of the above.

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103. Steam engine operates on

1. carnot cycle
2. joule cycle
3. Stirling cycle
4. brayton cycle
5. none of the above.

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104. Steam exhaust from high pressure turbine is reheated in

1. boiler drum
2. superheater tubes
3. economiser
4. a separate coil
5. a separate coil located in convection path.

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105. Steam in water tube boiler as compared to fire tube boiler

1. can be raised rapidly
2. is raisd at slower rate
3. is raised at same rate
4. could be raised at fast/slow rate depending on design
5. none of the above is true.

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106. Stoichiometric quantity of air is the

1. air present in atmosphere at NTP conditions
2. air required for complete combustion of fuel with no excess air
3. air required for optimum combustion so as to have reasonable excess air
4. air required to convert CO into C02
5. air required to form an explosive mixture.

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107. Sublimation region is the region where

1. solid and vapour phases are in equi-librium
2. solid and liquid phases are in equilibrium
3. liquid and vapour phases are in equilibrium
4. solid, liquid and vapour phases are in equilibrium
5. none of the above.

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108. Sulphur content of fuels is very important to the plant operators because it

1. has high heating value
2. retards electric precipitation
3. promotes complete combustion
4. has highly corrosive effect
5. facilitates ash removal.

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109. Sulphur in coal results in

1. causing clinkering and slagging
2. corroding air heaters
3. spontaneous combustion during coal storage
4. facilitating ash precipitation
5. all of the above.

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110. Superheating of steam is done at

1. constant volume
2. constant temperature
3. constant pressure
4. constant entropy
5. constant enthaply.

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