The steam enters the nozzle at a
High pressure and a low velocity
High pressure and a high velocity
Low pressure and a low velocity
Low pressure and a high velocity
Correct Answer :
A. High pressure and a low velocity
Related Questions
The ratio of brake power to the indicated power is known as
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Brake thermal efficiency
Steam in water tube boiler as compared to fire tube boiler
Can be raised rapidly
Is raised at slower rate
Is raised at same rate
Could be raised at fast/slow rate depending on design
The chimney draught varies with
Climatic conditions
Temperature of furnace gases
Height of chimney
All of these
In a reaction turbine, when steam flows through the fixed blades,
Pressure increases while velocity decreases
Pressure decreases while velocity increases
Pressure and velocity both decreases
Pressure and velocity both increases
The draught in locomotive boilers is produced by a
Chimney
Centrifugal fan
Steam jet
None of these
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
The efficiency of the plant __________ with the mechanical draught.
Increases
Decreases
Remains constant
None of these
Steam turbines may be classified according to
Direction of steam flow
Number of stages
Mode of steam action
All of these
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
For maximum discharge through a chimney, the condition is that height of hot gas column producing the draught should be
One-half the height of chimney
Equal to the height of chimney
Two times the height of chimney
Four times the height of chimney
In order to reduce the rotor speed of an impulse turbine, the method employed is
Velocity compounding
Pressure compounding
Pressure-velocity compounding
All of these
On Mollier chart, flow through turbine is represented by
Horizontal straight line
Vertical straight line
Straight inclined line
Curved line
The coal requirement per kW hour generation in the thermal power plant is of the order of
0.1 to 0.2 kg
0.2 to 0.4 kg
0.6 to 0.8 kg
1.0 to 1.5 kg
A single stage impulse turbine with a diameter of 1.2 m runs at 3000 r.p.m. If the blade speed ratio is 0.42, then the inlet velocity of steam will be
79 m/s
188 m/s
450 m/s
900 m/s
The ratio of the workdone on the blades to the energy supplied to the blades, is called
Blading efficiency
Nozzle efficiency
Gross or stage efficiency
Mechanical efficiency
The stage efficiency (ηS) is given by (where ηB = Blading efficiency, and ηN = Nozzle efficiency)
ηS = ηB × ηN
ηS = ηB / ηN
ηS = ηN / ηB
None of these
Pick up the wrong statement about critical condition of steam
Latent heat is zero
Liquid directly becomes steam
Specific volume of steam and liquid is same
This is the maximum pressure limit
The draught may be produced by a
Mechanical fan
Chimney
A steam jet
All of these
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
Which of the following statement is wrong?
The mechanical draught reduces the height of chimney.
The natural draught reduces the fuel consumption.
A balanced draught is a combination of induced and forced draught.
All of the above
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
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
Maximum energy loss in a boiler occurs due to
Unburnt carbon in ash
Incomplete combustion
Ash content
Flue gases
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
Reheating of steam under ideal conditions takes place at constant
Entropy
Enthalpy
Pressure
Temperature
Which of the following statement is correct?
A fire tube boiler occupies less space than a water tube boiler, for a given power.
Steam at a high pressure and in large quantities can be produced with a simple vertical boiler.
A simple vertical boiler has one fire tube.
All of the above
The diagram 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
The diameter of internal flue tubes of a Lancashire boiler is about _________ that of its shell.
One-fourth
One-third
Two-fifth
One-half
Clearance ratio is the ratio of
Clearance volume to the swept volume
Clearance volume to the volume at cut-off
Volume at cut-off to the swept volume
Swept volume to the clearance volume
The number of water level indicators in a boiler are generally _________ in number.
One
Two
Three
Four