The critical pressure ratio for initially superheated steam is __________ as compared to initially dry saturated steam.
More
Less
Same
None of these
Correct Answer :
B. Less
Related Questions
Locomotive boiler is of the following type
Multi tubular
Horizontal
Internally fired
All of the above
A device used to put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit, is called
Blow off cock
Stop valve
Superheater
None of these
The diameter of fire tubes in Cochran boiler is of the order of
2 cm
6 cm
8 cm
12 cm
The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is
Less
More
Equal
May be less or more depending on temperature
The diameter of Cornish boiler varies from
0.5 to 1 m
1 to 2 m
1.25 to 2.5 m
2 to 3 m
A steam turbine, in which a part of the steam after partial expansion, is used for process heating and the remaining steam is further expanded for power generation, is known as
Back pressure turbine
Pass out turbine
Low pressure turbine
Impulse turbine
A safety valve usually employed with stationary boilers is
Lever safety valve
Dead weight safety valve
High steam and low water safety valve
All of these
Which of the following statement indicates the difference between Cornish boiler and Lancashire boiler?
Cornish boiler is a water tube boiler whereas Lancashire boiler is a fire tube boiler
Cornish boiler is a fire tube boiler whereas Lancashire boiler is a water tube boiler
Cornish boiler has one flue tube whereas Lancashire boiler has two flue tubes
Cornish boiler has two flue tubes whereas Lancashire boiler has one flue tube
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
The radius of a dished head is taken approximately as
One fourth
Half
One
Two
Which is not correct statement about effect of sulphur in fuel?
It has heating value
It helps in electrostatic precipitation of ash in flue gases
It leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low
It erodes furnace walls
Equivalent evaporation is the amount of water evaporated in a boiler from and at
0°C
100°C
Saturation temperature at given pressure
Room temperature
The temperature of flue gases at air heater outlet should be
100°C
Above dew point temperature of flue gases
Below dew point temperature of flue gases
Less than wet bulb temperature of flue gases
In a nozzle, the effect of super-saturation is to
Decrease dryness fraction of steam
Decrease specific volume of steam
Increase the entropy
Increase the heat drop
Fire tube boilers are those in which
Flue gases pass through tubes and water around it
Water passes through the tubes and flue gases around it
Forced circulation takes place
Tubes are laid vertically
The critical pressure ratio for initially dry saturated steam is
0.546
0.577
0.582
0.601
A boiler in India should conform to safety regulations of
DIN
BS
ASTM
IBR
Which is not the correct statement about moisture in coal?
Inherent moisture and surface moisture are different things
In some coals moisture may be present up to 40%
Some moisture in coal helps in better burning which is not possible with completely dry coal
It increases thermal efficiency
The crown of the fire box is made hemispherical in order to
Give maximum space
Give maximum strength
Withstand pressure inside boiler
Resist intense heat in fire box
Which of the following statement is wrong?
Locomotive boiler is a water tube boiler
Water tube boilers are internally fired
Lamont boiler is a low pressure water tube boiler
All of the above
The water tubes in a simple vertical boiler are
Horizontal
Vertical
Inclined
None of these
The economiser is used in boilers to
Increase thermal efficiency of boiler
Economise on fuel
Extract heat from the exhaust flue gases
Increase flue gas temperature
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
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
Rateau turbine is
Simple reaction turbine
Velocity compounded turbine
Pressure compounded turbine
Pressure-velocity compounded turbine
Parson's reaction turbine is a __________ reaction turbine.
40 percent
50 percent
60 percent
70 percent
The evaporation of 15.653 kg of water per hour from and at 100°C is called
Evaporative capacity
Factor of evaporation
Equivalent evaporation
One boiler h.p.
Which of the following statement is correct for steam turbines as compared to reciprocating steam engines?
A steam turbine develops higher speeds
The efficiency of steam turbine is higher
The steam consumption is less
All of these
The flow of steam is supersonic
At the entrance to the nozzle
At the throat of the nozzle
In the convergent portion of the nozzle
In the divergent portion of the nozzle
When the inlet pressure of steam is equal to the exit pressure, then
There is a pressure drop in the nozzle
Fluid flows through the nozzle
Pressure drops and fluid flows through the nozzle
There is no pressure drop and fluid does not flow through the nozzle