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
Correct Answer :
C. Decreases
Related Questions
In locomotives, the draught is produced by
Chimney
Induced draft fan
Both combined (A) and (B)
Steam jet draught
Which of the following boiler is best suited to meet the fluctuating demand of steam?
Locomotive boiler
Lancashire boiler
Cornish boiler
Babcock and Wilcox boiler
An economiser is generally placed between
Last superheater or reheater and air preheater
Induced draft fan and forced draft fan
Air preheater and chimney
None of the above
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
The average value of diagram factor lies between
0.2 to 0.5
0.5 to 0.65
0.65 to 0.9
0.8 to 1.2
Which of the following is steam dial?
Non-coking bituminous coal
Brown coal
Pulverised coal
Coking bituminous coal
Which of the following boiler works on a forced circulation of water?
Lamont boiler
Benson boiler
Loeffler boiler
All of these
Which of the following coals has the highest calorific value?
Anthracite coal
Bituminous coal
Lignite
Peat
Lancashire boiler is used where working pressure and power required are
Low
Moderate
High
None of these
A nozzle is said to be a divergent 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
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
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
The compounding of turbines is done in order to
Reduce speed of rotor
Improve efficiency
Reduce exit losses
All of these
Gradually increasing temperature of flue gases at inlet to chimney for given steam outputs is an indication of
Higher effectiveness of boiler
High calorific value coal being burnt
Fouling of heat transfer surfaces
Raising of steam temperature
The state of vapour under saturation condition is described by
Pressure alone
Temperature alone
Pressure and temperature
Pressure and dryness fraction
A turbine is said to have an axial discharge when the steam leaves the blade tip at _________ to the direction of the blade motion.
60°
90°
180°
270°
Steam exhaust from high pressure turbine is reheated in
Boiler drums
Superheater tubes
Economiser
A separate coil located in convection path.
Which of the following is a water tube boiler?
Lancashire boiler
Babcock and Wilcox boiler
Locomotive boiler
Cochran boiler
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
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
A condenser where circulating water flows through tubes which are surrounded by steam, in known as
Surface condenser
Jet condenser
Barometric condenser
Evaporative condenser
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 efficiency of reaction turbine is maximum when (where α = Angle made by the absolute velocity V at inlet)
Vb = 0.5 V cosα
Vb = V cos α
Vb = 0.5 V² cosα
Vb = V² cosα
In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 mts. and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is
40 %
25 %
50 %
80 %
In forced 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 number of drums in Benson steam generator is
One
Two
One steam drum and one water drum
No drum
The steam temperature with increase in load in case of a boiler fitted with radiation superheater
Increases
Decreases
Remain unaffected
First increases and then decreases
In a single acting steam engine
The steam is admitted on one side of the piston and one working stroke is produced during each revolution of the crankshaft
The steam is admitted, in turn, on both sides of the piston and one working stroke is produced during each revolution of the crankshaft
The steam is admitted on one side of the piston and two working strokes are produced during each revolution of the crankshaft
The steam is admitted, in turn, on both sides of the piston and two working strokes are produced during each revolution of the crankshaft
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 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