During storage, the heating value of coal
Increases
Decreases
Remain constant
May increase or decrease depending upon the method of storage
Correct Answer :
B. Decreases
Related Questions
Water tube boilers are
Internally fired
Externally fired
Internally as well as externally fired
None of these
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
The equivalent evaporation of a boiler is a measure to compare
The given boiler with the model
The two different boilers of the same make
Two different makes of boilers operating under the same operating conditions
Any type of boilers operating under any conditions
The fire tubes in a Cochran boiler usually have _________ diameter.
6.25 mm
62.5 mm
72.5 mm
92.5 mm
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
Cochran boiler is a
Horizontal fire tube boiler
Horizontal water tube boiler
Vertical water tube boiler
Vertical fire tube boiler
An air preheater
Increases evaporative capacity of the boiler
Increases the efficiency of the boiler
Enables low grade fuel to be burnt
All of the above
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
The nozzle efficiency is the ratio of
Workdone on the blades to the energy supplied to the blades
Workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
Energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
None of the above
Gusset stays in a boiler are provided to
Prevent the bulging of flat surfaces
Avoid explosion in furnace
Prevent leakage of hot flue gases
Support furnace freely from top
The dry saturated steam at very low pressure, (510 kg/cm²) when throttled to atmosphere will become
Wet
Superheated
Remain dry saturated
Dry
The pressure of steam in the engine cylinder at the beginning of the stroke is ________ the boiler pressure.
Equal to
Less than
Higher than
None of these
The capacity of induced draft fan compared to forced draft fan in a boiler is
Same
More
Less
Less or more depending on size of boiler
Green coal, in order to be burnt, must be
Heated sufficiently
Burnt in excess air
Heated to its ignition point
Burnt as powder
The proximate analysis of fuel lists
Various chemical constituents, carbon, hydrogen, oxygen etc, plus ash as percents by volume
Various chemical constituents, carbon, hydrogen, oxygen, etc, plus ash as percents by weight
Fuel constituents as percents by volume of moisture, volatile, fixed carbon and ash
Fuel constituents as percents by weight of moisture, volatile, fixed carbon and ash
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
Efficiency of a thermal cycle increases by
Regeneration
Reheating of steam
Both (A) and (B)
Cooling of steam
Lancashire boiler is a
Stationary fire tube boiler
Stationary water tube boiler
Water tube boiler with natural/forced circulation
Mobile fire tube boiler
The pressure of feed water has to be raised before its entry into the boiler. The pressure is raised by a device known as
Feed pump
Injector
Feed check valve
Pressure gauge
Which type of boiler can meet rapid changes of load?
Vertical fire tube type
Horizontal fire tube type
Horizontal water tube type
Forced circulation type
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 pressure at which latent heat of vaporisation of water is zero, is
Below atmospheric pressure
1 kg/cm²
100 kg/cm²
225.6 kg/cm²
In impulse turbines, when friction is neglected, the relative velocity of steam at outlet tip of the blade is __________ the relative velocity of steam at inlet tip of the blade.
Equal to
Less than
Greater than
None of these
Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler
Increases
Decreases
Remain unaffected
First increases and then decreases
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
The action of steam in a steam turbine is
Static
Dynamic
Static and dynamic
Neither static nor dynamic
On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by
Horizontal straight line
Vertical straight line
Straight inclined line
Curved line
The impulse reaction turbine has its driving force
As an impulsive force
As a reaction force
Partly as an impulsive force and partly as a reaction force
None of the above
A throttle governed steam engine develops 15 kW with 280 kg per hour of steam and 35 kW with 520 kg per hour of steam. The steam consumption in kg per hour when developing 20 kW will be nearly
150 kg/h
210 kg/h
280 kg/h
340 kg/h
An impulse turbine as compared to a reaction turbine, for a given power has _________ row of blades.
Equal
Less
More
None of these