Desecration of feed water is carried out because it reduces
Cavitation of boiler feed pumps
Corrosion caused by oxygen
Heat transfer coefficient
pH value of water
Correct Answer :
B. Corrosion caused by oxygen
Related Questions
A condenser in a steam power plant
Increases expansion ratio of steam
Reduces back pressure of steam
Reduces temperature of exhaust steam
All of these
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
In fire tube boilers
Water passes through the tubes which are surrounded by flames and hot gases
The flames and hot gases pass through the tubes which are surrounded by water
Forced circulation takes place
None of these
Sulphur content of fuels is very important to the plant operators because it
Has high heating value
Retards electric precipitation
Promotes complete combustion
Has highly corrosive effect
Lancashire boiler has __________ internal flue tubes.
One
Two
Three
Four
In a boiler, feed water supplied per hour is 205 kg while coal fired per hour is 23 kg. The net enthalpy rise per kg of water is 145 kJ. If the calorific valve of the coal is 2050 kJ/kg, then the boiler efficiency will be
56 %
63 %
74 %
78 %
In a nozzle, whole frictional loss is assumed to occur between
Inlet and throat
Inlet and outlet
Throat and exit
All of these
The cylindrical shell of a Lancashire boiler has diameter from
1 to 2 m
1.25 to 2.25 m
1.5 to 2.5 m
1.75 to 2.75 m
In a throttling process
Steam temperature remains constant
Steam pressure remains constant
Steam enthalpy remains constant
Steam entropy remains constant
Mechanical equivalent of heat for 1 kcal or Joule's equivalent is equal to
421 kg.m
421 kg.m
539 kg.m
102 kg.m
The impulse turbine rotor efficiency will have a maximum value of 0.5 cos 2α, where α is the nozzle exit flow angle, if the
Blades are equiangular
Blade velocity coefficient is unity
Blades are equiangular and frictionless
Blade solidity is 0.65
For a Parson's reaction turbine, if α₁ and α₂ are fixed blade angles at inlet and exit respectively and β₁ and β₂ are the moving blade angles at entrance and exit respectively, then
α₁ = α₂ and β₁ = β₂
α₁ = β₁ and α₂= β₂
α₁ < β₁ and α₂ > β₂
α₁ = β₂ and β₁ = α₂
The draught produced by a steam jet issuing from a nozzle placed in the ash-pit under the fire grate of the furnace is called
Induced steam jet draught
Chimney draught
Forced steam jet draught
None of these
The factor of evaporation for all boilers is always
Equal to unity
Less than unity
Greater than unity
None of these
A compound steam engine in which piston rods of high pressure and low pressure cylinders are attached to two different cranks set at 90° to each other, is called
Receiver type compound engine
Tandem type compound engine
Woolf type compound engine
Both (A) and (B)
A valve installed between the boiler and the feed pump is
Blow off cock
Feed check valve
Steam stop valve
None of these
In a velocity compounded impulse turbine, when steam flows through the second row of moving blades,
Velocity increases
Velocity decreases
Velocity remains constant
Pressure remains constant
The maximum discharge through a chimney occurs when the height of chimney is
Infinitely long
Around 200 meters
Equal to the height of the hot gas column producing draught
Outside temperature is very low
The three Ts for good combustion are
Temperature, time, and turbulence
Total air, true fuel, and turbulence
Thorough mixing, total air and temperature
Total air, time, and temperature
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 correct statement about pulverised fuel firing?
High burning rate is possible
Heat release can be easily controlled
Fuel burns economically
It is the best technique for burning high ash content fuel having low fusion ash
The high pressure boiler is one, which produces steam at a pressure more than
Atmospheric pressure
5 kg/cm²
10 kg/cm²
7580 kg/cm²
Pick up wrong statement about desired properties of a good fuel
High calorific value
Produce minimum smoke and gases
Ease in storing
High ignition point
The performance of a boiler is measured by the
Amount of water evaporated per hour
Steam produced in kg/h
Steam produced in kg/kg of fuel burnt
All of these
A fusible plug is fitted in small boilers in order to
Avoid excessive build up of pressure
Avoid explosion
Extinguish fire if water level in the boiler falls below alarming limit
Control steam dome
Blading efficiency is also known as
Stage efficiency
Diagram efficiency
Nozzle efficiency
None of these
The velocity of steam at throat of the nozzle is __________ the velocity of sound.
Equal to
Less than
More than
None of these
A stage, in reaction turbine, is represented by
Number of casing
Number of entries of steam
Number of exits of steam
Each row of blades
When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be
Choked
Under-damping
Over-damping
None of these
Lancashire boiler is a
Stationary fire tube boiler
Stationary water tube boiler
Water tube boiler with natural/forced circulation
Mobile fire tube boiler