The aim of a compound steam engine is
To reduce the ratio of expansion in each cylinder
To reduce the length of stroke
To reduce the temperature range in each cylinder
All of the above
Correct Answer :
D. All of the above
Related Questions
Fire tube boilers are those in which
Flue gases pass through tubes and water around it
Water passes through the tubes and flue gases around it
Forced circulation takes place
Tubes are laid vertically
A _________ in a boiler is used to put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit.
Blow off cock
Fusible plug
Stop valve
Safety valve
Curtis turbine is a
Simple reaction turbine
Velocity compounded turbine
Pressure compounded turbine
Pressure-velocity compounded turbine
The best suited coal for chain or travelling grate stoker boiler is
Coking coal
Non-coking or free burning coal
Pulverised coal
High sulphur coal
The specific heat of superheated steam in kcal/kg is generally of the order of
0.1
0.3
0.5
0.8
The safety valve at superheater as compared to drum safety valve setting is set at
Higher value
Lower value
Same value
Any value
The pressure at which latent heat of vaporisation of water is zero, is
Below atmospheric pressure
1 kg/cm²
100 kg/cm²
225.6 kg/cm²
Cut-off ratio is the ratio of
Swept volume to the volume at cut-off
Volume at cut-off to the clearance volume
Volume at cut-off to the swept volume
Clearance volume to the volume at cut-off
The missing quantity per stroke is equal to
Cylinder feed indicated mass of steam
Cylinder feed + indicated mass of steam
Mass of cushion steam + indicated mass of steam
Mass of cushion steam + cylinder feed
An economiser is installed in a boiler primarily to
Superheat the steam
Reduce fuel consumption
Increase steam pressure
All of these
A vessel into which the steam is exhausted and condensed after doing work in an engine cylinder or turbine is known as
Steam condenser
Steam boiler
Steam preheater
Economiser
The main object of a boiler trial is
To determine the generating capacity of the boiler
To determine the thermal efficiency of the boiler when working at a definite pressure
To prepare heat balance sheet for the boiler
All of the above
Stage efficiency is also known as
Diagram efficiency
Nozzle efficiency
Gross efficiency
None of these
Boiler stays are used to
Prevent flat surfaces under pressure from tearing apart
Take care of failure in shear
Take care of failure in compression
Provide support for boiler
For the same diameter and thickness of tube, a water tube boiler compared to a fire tube boiler has
More heating surface
Less heating surface
Equal heating surface
Heating surface depends on other parameters
Which of the following is a fire tube boiler?
Locomotive boiler
Babcock and Wilcox boiler
Stirling boiler
All of the above
Sulphur content of fuels is very important to the plant operators because it
Has high heating value
Retards electric precipitation
Promotes complete combustion
Has highly corrosive effect
The difference of supersaturated temperature and saturation temperature at that pressure is called
Degree of super-saturation
Degree of superheat
Degree of under-cooling
None of these
The fusible plug in small boilers is located
In the drum
In the fire tubes
Above steam dome
Over the combustion chamber
If the critical pressure ratio for steam is 0.546, then the steam is initially
Wet steam
Dry saturated steam
Superheated steam
None of these
The device attached to the steam chest for preventing explosions due to excessive internal pressure of steam is called
Safety valve
Water level indicator
Pressure gauge
Fusible plug
In designing air preheaters, the important design consideration is that
Approach temperature should be as low as possible
Handling and maintenance should be easier
Heat transfer area should be optimum
Stack gases should not be cooled to the dew point
A safety valve in a locomotive starts leaking. The leaking medium will be
Water
Dry steam
Wet steam
Super heated steam
The fire tubes in a Cochran boiler usually have _________ diameter.
6.25 mm
62.5 mm
72.5 mm
92.5 mm
Water tube boilers are those in which
Flue gases pass through tubes and water around it
Water passes through the tubes and flue gases around it
Work is done during adiabatic expansion
Change in enthalpy
In reaction turbines, the axial thrust is due to
Pressure drop across the rotor
Change in axial velocity
Both (A) and (B)
None of these
The pressure of steam __________ while flowing through a nozzle.
Increases
Decreases
Remains constant
None of these
A throttle governed steam engine develops 15 kW with 280 kg per hour of steam and 35 kW with 520 kg per hour of steam. The steam consumption in kg per hour when developing 20 kW will be nearly
150 kg/h
210 kg/h
280 kg/h
340 kg/h
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
The ratio of brake power to the indicated power is known as
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Brake thermal efficiency