226. The critical pressure at which latent heat of vaporization is zero is
(A) 225.65 kgf/cm2
(B) 273 kgf/cm2
(C) 100 kgf/cm2
(D) 1 kgf/cm2
227. Water at a pressure of 4 kg/cm2 & 160° C temperature, when exposed to the atmosphere, will
(A) Boil
(B) Flash i.e get converted into steam
(C) Remain as it was
(D) Cool down
228. In an experiment to determine dryness fraction of steam, the mass of water separated was 0.6 kg in15 mts and the mass of steam passed out at the same time was 5.4 kg. Dryness fraction is
(A) 40%
(B) 25%
(C) 90%
(D) 80%
229. Potassium hydroxide is used in Orsat’s apparatus for the absorption of
(A) CO2
(B) CO
(C) O2
(D) N2
230. The efficiency of a thermal cycle increases by
(A) Regeneration
(B) Reheating of steam
(C) Both (A) and (B)
(D) Cooling of steam
231. What chemicals are added for residual dissolved oxygen?
(A) Sodium sulphite
(B) Hydrazine
(C) Carbohydrazide
(D) All of the mentioned
232. Why deaerator is not used in water cooled and moderated nuclear power plant?
(A) Radioactivity
(B) Not Economical
(C) Not safe
(D) Not mechanically possible
233. The specific volume of steam with increase in pressure decreases
(A) Linearly
(B) Slowly first and then rapidly
(C) Rapidly first and then slowly
(D) Inversely
234. Stoichiometric quantity of air is the
(A) Air present in the atmosphere at NTP conditions
(B) The air required for complete combustion of the fuel with no excess air
(C) Air required for optimum combustion so as to have reasonable excess air
(D) The air required to convert CO into CO2
235. The latent heat of steam with the increase of pressure
(A) Remains the same
(B) Increase
(C) Decrease
(D) Behaves unpredictably
236. Locomotive type boiler is
(A) Horizontal multi-tubular water tube boiler
(B) Water wall enclose furnace type
(C) Vertical tubular fire tube type
(D) Horizontal multi-tubular fire tube boiler
237. Fusible plug for boilers is made of a fusible metal containing tin, lead, and
(A) Bismuth
(B) Copper
(C) Nickel
(D) Iron
238. Boiler H.P is defined as the
(A) Steam evaporation rate per kg of fuel fired
(B) Work was done in evaporating 1 kg of steam per hour from and at 100° C into dry saturated steam
(C) The evaporation of 15.65 kg of water per hour from and at 100° C into dry saturated steam
(D) Work is done by 1 kg of steam at saturation condition
239. Boiler stays are used to
(A) Prevent flat surfaces under pressure from tearing apart
(B) Take care of failure in shear
(C) Take care of failure compression
(D) Provide the foundation of boiler
240. In designing air preheater the important design consideration is that
(A) Approach temperature should be as low as possible
(B) Handing and maintenance should be easier
(C) Heat transfer area should be optimum
(D) Stack gases should not be cooled to the dew point
241. Primary air is the air used to
(A) Provide air around burners for obtaining optimum combustion
(B) Transport and dry the coal
(C) Convert CO (formed in the lower zone of the furnace) into CO2 at higher zone
(D) Air-delivered by forced draft fan
242. Sulphur content of fuels is very important to the plant operators because of it
(A) Has the high heating value
(B) Retards electric precipitation
(C) Promotes complete combustion
(D) Has a highly corrosive effect
243. Presence of moisture in fuel oil would
(A) Keep the burner tips cool
(B) Aid in proper combustion
(C) Cause sputtering, possibly extinguishing the flame
(D) Clean the nozzles
244. Tertiary air is the air used to
(A) Provide air around burners for obtaining optimum combustion
(B) Cool the scanners
(C) Supply air for ignitors
(D) Convert CO (formed in the lower zone of furnace) into CO2 at higher zone
245. Overfire burning is the phenomenon of
(A) Supply of excess air
(B) Supply of excess coal
(C) Burning CO and unburnt in the upper zone of the furnace by supplying more air
(D) Fuel bed firing
246. The blowdown cock in the boiler is used for
(A) Regulating drum level by blowing unwanted water
(B) Emptying the boiler in case of shut down
(C) Maintaining constant pressure in the drum by blowing unwanted steam
(D) To remove sludge or sediments from the drum
247. Which one of the following safety devices are used to protect the boiler when the water level fails below a minimum level?
(A) Water level indicator
(B) Fusible plug
(C) Blow off cock
(D) Safety valve
248. In a boiler following data given.
1. Quantity of steam(dry) generated 12 TPH
2. Quantity of coal consumed 2.7 TPH
3. Net enthalpy rise per kg of steam is 540 kcal
4. GCV of coal is 3000 kcal/ kg
5. Steam pressure & temperature is 10 kg/cm2 at 180° C
What will be the boiler efficiency?
(A) 60%
(B) 80%
(C) 75%
(D) 85%
249. Steam is generated in a boiler at 110 kg/cm2 and 522° C. Drum pressure of the boiler is 118 kg/cm2.Calculate degree of superheat. [Saturated steam temperature corresponding to 118 kg/cm2 is 322° Cand 110 kg/cm2 is 317° C]
(A) 200° C
(B) 205° C
(C) 844° C
(D) 839° C
250. The safety valve of a boiler is set at 40 kg/cm2. During testing, it is found that the valve lifts at 44 kg/cm2 and reset at 38 kg/cm2. Calculate over pressure percentage.
(A) 5%
(B) 9.1%
(C) 15%
(D) 10%
(A) 225.65 kgf/cm2
(B) 273 kgf/cm2
(C) 100 kgf/cm2
(D) 1 kgf/cm2
227. Water at a pressure of 4 kg/cm2 & 160° C temperature, when exposed to the atmosphere, will
(A) Boil
(B) Flash i.e get converted into steam
(C) Remain as it was
(D) Cool down
228. In an experiment to determine dryness fraction of steam, the mass of water separated was 0.6 kg in15 mts and the mass of steam passed out at the same time was 5.4 kg. Dryness fraction is
(A) 40%
(B) 25%
(C) 90%
(D) 80%
229. Potassium hydroxide is used in Orsat’s apparatus for the absorption of
(A) CO2
(B) CO
(C) O2
(D) N2
230. The efficiency of a thermal cycle increases by
(A) Regeneration
(B) Reheating of steam
(C) Both (A) and (B)
(D) Cooling of steam
231. What chemicals are added for residual dissolved oxygen?
(A) Sodium sulphite
(B) Hydrazine
(C) Carbohydrazide
(D) All of the mentioned
232. Why deaerator is not used in water cooled and moderated nuclear power plant?
(A) Radioactivity
(B) Not Economical
(C) Not safe
(D) Not mechanically possible
233. The specific volume of steam with increase in pressure decreases
(A) Linearly
(B) Slowly first and then rapidly
(C) Rapidly first and then slowly
(D) Inversely
234. Stoichiometric quantity of air is the
(A) Air present in the atmosphere at NTP conditions
(B) The air required for complete combustion of the fuel with no excess air
(C) Air required for optimum combustion so as to have reasonable excess air
(D) The air required to convert CO into CO2
235. The latent heat of steam with the increase of pressure
(A) Remains the same
(B) Increase
(C) Decrease
(D) Behaves unpredictably
236. Locomotive type boiler is
(A) Horizontal multi-tubular water tube boiler
(B) Water wall enclose furnace type
(C) Vertical tubular fire tube type
(D) Horizontal multi-tubular fire tube boiler
237. Fusible plug for boilers is made of a fusible metal containing tin, lead, and
(A) Bismuth
(B) Copper
(C) Nickel
(D) Iron
238. Boiler H.P is defined as the
(A) Steam evaporation rate per kg of fuel fired
(B) Work was done in evaporating 1 kg of steam per hour from and at 100° C into dry saturated steam
(C) The evaporation of 15.65 kg of water per hour from and at 100° C into dry saturated steam
(D) Work is done by 1 kg of steam at saturation condition
239. Boiler stays are used to
(A) Prevent flat surfaces under pressure from tearing apart
(B) Take care of failure in shear
(C) Take care of failure compression
(D) Provide the foundation of boiler
240. In designing air preheater the important design consideration is that
(A) Approach temperature should be as low as possible
(B) Handing and maintenance should be easier
(C) Heat transfer area should be optimum
(D) Stack gases should not be cooled to the dew point
241. Primary air is the air used to
(A) Provide air around burners for obtaining optimum combustion
(B) Transport and dry the coal
(C) Convert CO (formed in the lower zone of the furnace) into CO2 at higher zone
(D) Air-delivered by forced draft fan
242. Sulphur content of fuels is very important to the plant operators because of it
(A) Has the high heating value
(B) Retards electric precipitation
(C) Promotes complete combustion
(D) Has a highly corrosive effect
243. Presence of moisture in fuel oil would
(A) Keep the burner tips cool
(B) Aid in proper combustion
(C) Cause sputtering, possibly extinguishing the flame
(D) Clean the nozzles
244. Tertiary air is the air used to
(A) Provide air around burners for obtaining optimum combustion
(B) Cool the scanners
(C) Supply air for ignitors
(D) Convert CO (formed in the lower zone of furnace) into CO2 at higher zone
245. Overfire burning is the phenomenon of
(A) Supply of excess air
(B) Supply of excess coal
(C) Burning CO and unburnt in the upper zone of the furnace by supplying more air
(D) Fuel bed firing
246. The blowdown cock in the boiler is used for
(A) Regulating drum level by blowing unwanted water
(B) Emptying the boiler in case of shut down
(C) Maintaining constant pressure in the drum by blowing unwanted steam
(D) To remove sludge or sediments from the drum
247. Which one of the following safety devices are used to protect the boiler when the water level fails below a minimum level?
(A) Water level indicator
(B) Fusible plug
(C) Blow off cock
(D) Safety valve
248. In a boiler following data given.
1. Quantity of steam(dry) generated 12 TPH
2. Quantity of coal consumed 2.7 TPH
3. Net enthalpy rise per kg of steam is 540 kcal
4. GCV of coal is 3000 kcal/ kg
5. Steam pressure & temperature is 10 kg/cm2 at 180° C
What will be the boiler efficiency?
(A) 60%
(B) 80%
(C) 75%
(D) 85%
249. Steam is generated in a boiler at 110 kg/cm2 and 522° C. Drum pressure of the boiler is 118 kg/cm2.Calculate degree of superheat. [Saturated steam temperature corresponding to 118 kg/cm2 is 322° Cand 110 kg/cm2 is 317° C]
(A) 200° C
(B) 205° C
(C) 844° C
(D) 839° C
250. The safety valve of a boiler is set at 40 kg/cm2. During testing, it is found that the valve lifts at 44 kg/cm2 and reset at 38 kg/cm2. Calculate over pressure percentage.
(A) 5%
(B) 9.1%
(C) 15%
(D) 10%
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