One kg of steam sample contains 0.8 kg dry steam; Its dryness fraction is
0.2
0.8
1.0
0.6
Correct Answer :
B. 0.8
Related Questions
All steam engines work on
Zeroth law of thermodynamics
First law of thermodynamics
Second law of thermodynamics
None of these
The rate of steam produced in Benson boiler is
100 tonnes/h
135 tonnes/h
175 tonnes/h
250 tonnes/h
The flow of steam is supersonic
At the entrance to the nozzle
At the throat of the nozzle
In the convergent portion of the nozzle
In the divergent portion of the nozzle
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
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
The fire tubes in a Locomotive boiler has _________ diameter.
4.75 mm
5.47 mm
7.45 mm
47.5 mm
The ratio of total useful heat drop to the total isentropic heat drop, is called
Stage efficiency
Internal efficiency
Rankine efficiency
None of these
Coke is produced by
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
Enriching carbon in the coal
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
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)
The efficiency of an impulse turbine is maximum when (where Vb = Blade speed, V = Absolute velocity of steam entering the blade, and α = Nozzle angle)
Vb = 0.5 V cosα
Vb = V cosα
Vb = 0.5 V² cosα
Vb = V² cosα
If partial pressure of air and steam be pa and ps respectively in a condenser, then according to Dalton's law, the pressure in condenser is equal to
ps - pa
pa - ps
pa + ps
None of these
Which of the following statement is correct?
The expansion of steam in a nozzle follows Rankine cycle.
The friction in the nozzle increases the dryness fraction of steam.
The pressure of steam at throat is called critical pressure.
All of the above
A device used in a boiler to control the flow of steam from the boiler to the main pipe and to shut off the steam completely when required, is known as
Blow off cock
Fusible plug
Superheater
Stop valve
Duplex feed pumps are used in small steam boilers. These operate on the principle of
Centrifugal pump
Axial flow pump
Gear pump
Reciprocating pump
The length of Lancashire boiler varies from
5 to 6 m
6 to 7 m
7.25 to 9 m
9 to 10 m
When the total heat of steam is h kJ/kg and the sensible heat of feed water is hf1 kJ/kg, then the factor of evaporation is given by
(h - hf1)/2257
(h + hf1)/2257
(h × hf1)/2257
None of these
The compounding of turbines is done in order to
Reduce speed of rotor
Improve efficiency
Reduce exit losses
All of these
The forced circulation of water does not take place in
LaMont boiler
Lancashire boiler
Velox boiler
Benson boiler
In a steam condenser, the partial pressure of steam and air are 0.06 bar and 0.007 bar respectively. The condenser pressure is
0.007 bar
0.053 bar
0.06 bar
0.067 bar
Spontaneous combustion is a phenomenon in which
All the fuel burns instantaneously producing high energy release
Fuel burns with less air
Coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
Explosion in furnace
Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler
Increases
Decreases
Remain unaffected
First increases and then decreases
In water 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
The process of draining steam from the turbine, at certain points during its expansion and using this steam for heating the feed water in feed water heaters and then supplying it to the boiler is known as
Regenerative heating
Reheating of steam
Bleeding
None of these
The water tubes in a simple vertical boiler are
Horizontal
Vertical
Inclined
None of these
Fusible plug for boilers is made of fusible metal containing tin, lead, and
Bismuth
Copper
Aluminium
Nickel
An economiser is installed in a boiler primarily to
Superheat the steam
Reduce fuel consumption
Increase steam pressure
All of these
In order to compare the capacity of boilers, the feed water temperature and working pressure are taken as
50°C and normal atmospheric pressure
50°C and 1.1 bar pressure
100°C and normal atmospheric pressure
100°C and 1.1 bar pressure
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
In a compound steam engine, the first stage of expansion is carried out in a high pressure cylinder whereas the last expansion is completed in low pressure cylinder. The diameter of high pressure cylinder is _________ the low pressure cylinder.
Equal to
Less than
More than
None of these