Steam coal is
Pulverized coal
Hard coke
Non-coking bituminous
Anthracite coal
The engine exhaust is made to pass through a convergent pipe on its way to the short chimney, thereby producing an induced draught. This is done in
Lancashire boiler
Locomotive boiler
Babcock-wilcox boiler
Marine boiler
Steamjet draught is invariably used in
Lancashire boiler
Locomotive boiler
Babcock- wilcox boiler
Cornish boiler
Which is not true in the context of comparison between induced fan draught and forced fan draught?
In induced draught, the fan is placed near or at the base of chimney. In forced draught, the fan or blower is placed at the base of boiler grate
Forced draught fan provides more uniform flow of air through the grate
With forced draught all leakages are outward whereas in induced draught, the infiltration is inwards
For the same mass flow rate and draught, the forced draught, the forced draught fan requires more power as compared to that required by induced draught
A steam nozzle is said to be choked when
There is stoppage of flow through the nozzle
Flow rate connot be increased by increasing the supply pressure
Critical conditions prevail and mass flow rate is maximum
Shock effect is felt in the nozzle
All of the following statements are correct, except
A convergent nozzle is used if the exit pressure is equal to or less than critical pressure
In a convergen-divergent nozzle, the flow velocity at the throat reaches the sonic velocity
Sonic speed represents the maximum speed at which a pressure wave can be transmitted
The nozzle is said to be choked when the flow rate is maximum
In a convergent nozzle, the mass flow rate is not a function of
Initial pressure of steam
Initial condition of steam; whether wet, dry or superheated
Throat diameter
Exit condition of steam
In a nozzle designed for maximum discharge conditions, the flow velocity in the convergent section of a nozzle is
Subsonic
Sonic
Supersonic
Depends upon the initial pressure and condition of steam.
In a steam nozzle, inlet pressure of superheated steam is 10bar. The exit pressure is decreased from 3bar to 1bar. The discharge rate will
Remain constant
Decrease
Increase slightly
Increase or decrease depending on whether the nozzle is converboilergent or convergent-divergent
Which is not true regarding effect of friction loss in a nozzle?
Reduction in exit velocity
Increase in final dryness friction
Increase in specific volume of steam
Increase in mass flow rate
The frictional loss in a well-designed nozzle is of the order of
Less than 5%
5-8%
10-15%
15-25%
The effect of friction on flow of steam through a nozzle is to
Decrease the mass flow rate and to increase the wetness at exit
Increase the mass flow rate and to increase the exit temperature
Decrease the mass flow rate and to decrease the wetness of steam
Increase the exit temperature without any effect on mass flow rate.
The effect of friction in a steam nozzle is to……….velocity and ………..dryness friction
Increase, increase
Increase, decrease
Decrease, increase
Decrease, decrease
The expansion of steam through a nozzle is so rapid that steam may not get time to condense and may remain in a state of homogeneous vapour. The expansion process is then stated to be
Critical
Thermally equilibrium
Metastable
Supersaturated
When compared to stable flow, the available enthalpy drop for supersaturated flow of steam through a nozzle
Remains same
Increases
Decreases
Is unpredictable