Which of the following statement is correct?
A fire tube boiler occupies less space than a water tube boiler, for a given power.
Steam at a high pressure and in large quantities can be produced with a simple vertical boiler.
A simple vertical boiler has one fire tube.
All of the above
Correct Answer :
C. A simple vertical boiler has one fire tube.
Related Questions
Which of the following gases has the highest calorific value?
Producer gas
Coal gas
Water gas
Blast furnace gas
A double acting steam engine with a cylinder diameter of 190 mm and a stroke of 300 mm has a cut-off of 0.35. The expansion ratio for this engine is nearly
1.05
2.86
6.65
10.05
A wet vapour can be completely specified by
Pressure only
Temperature only
Dryness fraction only
Pressure and dryness fraction
The feed check valve is used in order to
Regulate flow of boiler water
Check level of water in boiler drum
Recirculate unwanted feed water
Allow high pressure feed water to flow to drum and not allow reverse flow to take place
The aim of a compound steam engine is
To reduce the ratio of expansion in each cylinder
To reduce the length of stroke
To reduce the temperature range in each cylinder
All of the above
Film boiling occurs at
Very low pressure
Atmospheric pressures
Medium pressures
Very high pressures
The efficiency of a boiler is defined as
Ratio of heat actually used in producing steam to the heat liberated in the furnace
Ratio of the mass of steam produced to the mass of total water supplied in a given time
Ratio of the heat liberated in the furnace to the heat actually used in producing steam
None of the above
The safety valve on boiler drum compared to safety valve on superheater is set at
Same value
Higher value
Lower value
Lower/higher depending on steam flow
Which of the following is a water tube boiler?
Lancashire boiler
Babcock and Wilcox boiler
Locomotive boiler
Cochran boiler
The average value of diagram factor lies between
0.2 to 0.5
0.5 to 0.65
0.65 to 0.9
0.8 to 1.2
In an impulse reaction turbine, the pressure drops gradually and continuously over
Fixed blades
Moving blades
Both fixed and moving blades
None of these
On Mollier chart, flow through turbine is represented by
Horizontal straight line
Vertical straight line
Straight inclined line
Curved line
Over fire burning is the phenomenon of
Supply of excess, air
Supply of excess coal
Burning CO and unburnts in upper zone of furnace by supplying more air
Fuel bed firing
Throttle governing of steam engines is a method of controlling the engine output by varying
Volume of intake steam
Pressure of intake steam
Temperature of intake steam
All of these
The effect of friction on the flow of steam through a nozzle is to
Decrease the mass flow rate and to increase the wetness of steam
Increase the mass flow rate and to increase the exit temperature
Decrease the mass flow rate and to decrease the wetness of steam
Increase the exit temperature without any effect on mass flow rate
Which of the following statement is correct?
The expansion of steam in a nozzle follows Rankine cycle.
The friction in the nozzle increases the dryness fraction of steam.
The pressure of steam at throat is called critical pressure.
All of the above
Hard coke is produced by carburisation of coal at
Atmospheric temperature
500-600°C
700-850°C
950-1100°C
The diameter of a cylindrical shell of a Scotch marine boiler varies from
1.5 to 2 m
2.5 to 3.5 m
3.5 to 4.5 m
None of these
Which of the following statement is wrong?
The critical pressure gives the velocity of steam at the throat equal to the velocity of sound.
The flow in the convergent portion of the nozzle is subsonic.
The flow in the divergent portion of the nozzle is supersonic.
To increase the velocity of steam above sonic velocity (supersonic) by expanding steam below the critical pressure, the divergent portion for the nozzle is not necessary.
The difference of supersaturated temperature and saturation temperature at that pressure is called
Degree of super-saturation
Degree of superheat
Degree of under-cooling
None of these
The average operating pressure of Benson boiler is
100 bar
150 bar
200 bar
250 bar
A device used to increase the temperature of saturated steam without raising its pressure, is called
Blow off cock
Fusible plug
Superheater
Stop valve
The amount of water evaporated in kg per kg of fuel burnt is called
Evaporative capacity of a boiler
Equivalent evaporation from and at 100° C
Boiler efficiency
None of these
There is always some steam left in the clearance space from the previous stroke. This steam left in the clearance space is called
Wet steam
Saturated steam
Superheated steam
Cushion steam
Tertiary air is the air used to
Provide air around burners for obtaining optimum combustion
Transport and dry the coal
Cool the scanners
Convert CO (formed in lower zone of furnace) into CO₂ at higher zone.
The coal requirement per kW hour generation in the thermal power plant is of the order of
0.1 to 0.2 kg
0.2 to 0.4 kg
0.6 to 0.8 kg
1.0 to 1.5 kg
Maximum energy loss in a boiler occurs due to
Unburnt carbon in ash
Incomplete combustion
Ash content
Flue gases
A nozzle is said to be a convergent nozzle
When the cross-section of the nozzle increases continuously from entrance to exit
When the cross-section of the nozzle decreases continuously from entrance to exit
When the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
None of the above
Hard coke is used in
Cement industry
Thermal power plant
Blast furnace
Domestic use
Sublimation region is the region where
Solid and vapour phases are in equilibrium
Solid and liquid phases are in equilibrium
Liquid and vapour phases are in equilibrium
Solid, liquid and vapour phases are in equilibrium