The diameter of internal flue tubes of a Lancashire boiler is about _________ that of its shell.
One-fourth
One-third
Two-fifth
One-half
Correct Answer :
C. Two-fifth
Related Questions
A compound steam engine in which piston rods of high pressure and low pressure cylinders ' are attached to two different cranks set at 180° to each other, is called
Receiver type compound engine
Tandem type compound engine
Woolf type compound engine
Both (A) and (B)
The diameter of fire tubes in Cochran boiler is of the order of
2 cm
6 cm
8 cm
12 cm
Latent heat of dry steam at atmospheric pressure is equal to
539 kcal/ kg
539 BTU/ lb
427 kcal/ kg
100 kcal/ kg
Efficiency of Rankine cycle can be increased by
Decreasing initial steam pressure and temperature
Increasing exhaust pressure
Decreasing exhausts pressure
Increasing the expansion ratio
The velocity of steam leaving the nozzle (V) is given by (where K = Nozzle coefficient or nozzle efficiency, and hd = Enthalpy or heat drop during expansion of steam in a nozzle)
V = 44.72 hd K
V = 44.72 K hd
V = 44.72 K hd
V = 44.72 K hd
The increase in pressure
Lowers the boiling point of a liquid
Raises the boiling point of a liquid
Does not affects the boiling point of a liquid
Reduces its volume
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
In recuperative air preheaters, the heat is transferred
From a metal wall from one medium to another
From heating an intermediate material and then heating the air from this material
By direct mixing,
Heat is transferred by bleeding some gases from furnace
The height of chimney in a power plant is governed by
The draft to be created
Limitation of construction facilities
Control of pollution
Quantity of flue gases to be handled
The air pressure at the fuel bed is reduced below that of atmosphere by means of a fan placed at or near the bottom of the chimney to produce a draught. Such a draught is called
Natural draught
Induced draught
Forced draught
Balanced draught
The device attached to the steam chest for preventing explosions due to excessive internal pressure of steam is called
Safety valve
Water level indicator
Pressure gauge
Fusible plug
The relative heat absorption for successively added equal areas of boiler convection heating surfaces
Increases
Decreases
Remain unaffected
First increases and then decreases
The ratio of total useful heat drop to the total isentropic heat drop, is called
Stage efficiency
Internal efficiency
Rankine efficiency
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.
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
For the same diameter and thickness of tube, a water tube boiler has ________ heating surface as compared to fire tube boiler.
More
Less
Equal
None 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 cross compounding, the cylinders are arranged
Side by side and each cylinder has common piston, connecting rod and crank
Side by side and each cylinder has separate piston, connecting rod and crank
At 90° and each cylinder has common piston, connecting rod and crank
At 90° and each cylinder has separate piston, connecting rod and crank
The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.
Remains same
Decreases
Increases
None of these
The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ numbers of stages are required.
More
Less
Equal
None of these
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
Boiler stays are used to
Prevent flat surfaces under pressure from tearing apart
Take care of failure in shear
Take care of failure in compression
Provide support for boiler
The ratio of the actual vacuum to the ideal vacuum in a condenser is called
Condenser efficiency
Vacuum efficiency
Nozzle efficiency
Boiler efficiency
Presence of moisture in fuel oil would
Keep the burner tips cool
Aid in proper combustion
Because sputtering, possibly extinguishing flame
Clean the nozzles
The supersaturated flow of steam through a nozzle as compared to a stable flow, the available heat drop
Remains the same
Increases
Decreases
Is unpredictable
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
In a throttling process
Heat transfer takes place
Work is done by the expanding steam
Internal energy of steam changes
None of the above
In order to obtain superheated steam, a superheater is added in an existing boiler. As as result, furnace vacuum will
Remain unaffected
Improve
Worsen
May improve/worsen depending on size
In water wall furnace, the heat is transferred to the water walls by
Convection
Radiation
Conduction
Radiation and conduction
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