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
Correct Answer :
B. When the cross-section of the nozzle decreases continuously from entrance to exit
Related Questions
Reheating of steam under ideal conditions takes place at constant
Entropy
Enthalpy
Pressure
Temperature
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
When the inlet pressure of steam is equal to the exit pressure, then
There is a pressure drop in the nozzle
Fluid flows through the nozzle
Pressure drops and fluid flows through the nozzle
There is no pressure drop and fluid does not flow through the nozzle
At critical point, i.e. p = 225.65 kg/cm², the latent enthalpy of vaporisation is
Maximum
Minimum
Zero
Depends on temperature also
The object of producing draught in a boiler is
To provide an adequate supply of air for the fuel combustion
To exhaust the gases of combustion from the combustion chamber
To discharge the gases of combustion to the atmosphere through the chimney
All of the above
The function of a crosshead is to guide motion of the _________ and to prevent it from bending.
Piston rod
Connecting rod
Eccentric rod
Valve rod
A safety valve mainly used with locomotive and marine boilers is
Lever safety valve
Dead weight safety valve
High steam and low water safety valve
Spring loaded safety valve
The diameter of tubes for natural circulation boiler as compared to controlled circulation boilers is
More
Less
Same
Could be more or less depending on other factors
The bituminous coal is no caking if its carbon content is
78-81 %
81-85 %
85-90 %
90-95 %
Expanding steam to a very low pressure (high vacuum) in steam engines is
Desirable
Economical
Essential
Uneconomical
The safety valve at superheater as compared to drum safety valve setting is set at
Higher value
Lower value
Same value
Any value
The flow through a nozzle is regarded as
Constant volume flow
Constant pressure flow
Isothermal flow
Isentropic flow
The diameter of flue tube in a Cornish boiler is _________ that of the shell.
One-fourth
One-third
Two-fifth
Three-fifth
The forced circulation of water does not take place in
LaMont boiler
Lancashire boiler
Velox boiler
Benson boiler
The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is
Less
More
Equal
May be less or more depending on temperature
Blading efficiency is also known as
Stage efficiency
Diagram efficiency
Nozzle efficiency
None of these
The rate of steam produced in Benson boiler is
100 tonnes/h
135 tonnes/h
175 tonnes/h
250 tonnes/h
Which type of boiler can meet rapid changes of load?
Vertical fire tube type
Horizontal fire tube type
Horizontal water tube type
Forced circulation type
A steam turbine, in which a part of the steam after partial expansion, is used for process heating and the remaining steam is further expanded for power generation, is known as
Back pressure turbine
Pass out turbine
Low pressure turbine
Impulse turbine
The discharge is __________ at critical pressure.
Zero
Minimum
Maximum
None of these
The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.
Remains same
Decreases
Increases
None of these
An air preheater
Increases evaporative capacity of the boiler
Increases the efficiency of the boiler
Enables low grade fuel to be burnt
All of the above
The indicated thermal efficiency is defined as the
Ratio of thermal efficiency to the Rankine efficiency
Ratio of brake power to the indicated power
Ratio of heat equivalent to indicated power to the energy supplied in steam
Product of thermal efficiency and Rankine efficiency
The dry saturated steam at very high pressure (150200 kg/cm²) when throttled to atmosphere will become
Wet
Superheated
Remain dry saturated
Dry
The overall efficiency of thermal power plant is
Boiler efficiency, turbine efficiency, generator efficiency
All the three above plus gas cycle efficiency
Carnot cycle efficiency
Regenerative cycle efficiency
In locomotive boiler, maximum steam pressure is limited to
1 kg/cm²
5 kg/cm²
10 kg/cm²
18 kg/cm²
The expansion of steam, as it flows over the blades in reaction turbine, represents
Isothermal process
Isentropic process
Throttling process
Free expansion process
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 biggest size of thermal power unit operating in India is
30 MW
60 MW
100 MW
500 MW
Rateau turbine is
Simple reaction turbine
Velocity compounded turbine
Pressure compounded turbine
Pressure-velocity compounded turbine