Efficiency of a thermal cycle increases by
Regeneration
Reheating of steam
Both (A) and (B)
Cooling of steam
Correct Answer :
C. Both (A) and (B)
Related Questions
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
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
Primary air is the air used to
Provide air around burners for obtaining optimum combustion
Transport and dry the coal
Convert CO (formed in lower zone of furnace) into CO₂ at higher zone
Air delivered by forced draft fan
The pressure of steam __________ while flowing through a nozzle.
Increases
Decreases
Remains constant
None of these
The friction present between the steam and the nozzle surfaces reduces the heat drop by
10 to 15 %
15 to 25 %
25 to 40 %
40 to 60 %
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
The difference between Cornish boiler and Lancashire boiler is that
Former is fire tube type and latter is water tube type boiler
Former is water tube type and latter is fire tube type
Former contains one fire tube and latter contains two fire tubes
None/of the above
With increase in load, radiant superheater has
Drooping characteristic
Linear characteristic
Rising characteristic
Flat characteristic
The size of a boiler drum in pulverised fuel fired boiler, as its size and capacity, (steam pressure and flow ratings) increase
Increases
Decreases
Remains unchanged
Increases/decreases depending on steam temperature requirements
In natural circulation type boiler,
Heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum
Water is supplied in drum and through down comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam
Feed pump is employed to supplement natural circulation in water wall type furnace
Water is converted into steam in one. Pass without any recirculation
Expanding steam to a very low pressure (high vacuum) in steam engines is
Desirable
Economical
Essential
Uneconomical
The draught in locomotive boilers is produced by a
Chimney
Centrifugal fan
Steam jet
None of these
Carbonisation of coal is the process of
Pulverising coal in inert atmosphere
Heating wood in a limited supply of air at temperatures below 300°C
Strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
Binding the pulverised coal into briquettes
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
Lancashire boiler is a
Stationary fire tube boiler
Stationary water tube boiler
Water tube boiler with natural/forced circulation
Mobile fire tube boiler
In a Parson's turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be
160/3 m/s
320/3 m/s
640/3 m/s
640 m/s
The diameter of fire tube of Cornish boiler compared to its shell is
One half
One third
One fourth
One fifth
The condition of steam in boiler drum is always
Dry
Wet
Saturated
Supersaturated
Which of the following gases has the highest calorific value?
Producer gas
Coal gas
Water gas
Blast furnace gas
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.
Which of the following is required for a steam condensing plant?
Condenser
Condensate pump
Air extraction pump
All of these
The length of shell of a Locomotive boiler is
1 m
2 m
3 m
4 m
Equivalent evaporation of water is the evaporation for a feed water supply at 100°C
And its corresponding conversion into dry saturated steam at 100°C and 1.033 kg/cm²
And its corresponding conversion into dry steam at desired boiler pressure
Conversion into steam at atmospheric condition
Conversion into steam at the same pressure at which feed water is supplied
The ratio of heat actually used in producing the steam to the heat liberated in the furnace, is known as
Equivalent evaporation
Factor of evaporation
Boiler efficiency
Power of a boiler
In a uniflow engine
Steam enters and exhausts through the same port
Steam enters at one end and exhausts at the centre
Steam enters at the centre and exhausts at the other end
None of the above
The diameter of flue tube in a Cornish boiler is _________ that of the shell.
One-fourth
One-third
Two-fifth
Three-fifth
Which of the following statement is wrong?
The factor of evaporation for all boilers is always greater than unity.
The amount of water evaporated in kg per kg of fuel burnt is called equivalent evaporation from and at 100° C.
The ratio of heat actually used in producing the steam to the heat liberated in the furnace is called boiler efficiency.
None of the above
Besides mean effective pressure, the data required to determine the indicated power of an engine include
Piston diameter, length of stroke and calorific value of fuel
Piston diameter, specific fuel consumption and Calorific value of fuel
Piston diameter, length of stroke and speed of rotation
Specific fuel consumption, speed of rotation and torque
Fire tube boilers are limited to a maximum design working pressure of
1 kg/cm
6 kg/cm
17 kg/cm²
100 kg/cm²
If a steam sample is nearly in dry condition, then its dryness fraction can be most accurately determined by
Throttling calorimeter
Separating calorimeter
Combined separating and throttling calorimeter
Bucket calorimeter