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
Correct Answer :
A. Last superheater or reheater and air preheater
Related Questions
Which is not correct statement about the function of furnace?
To provide proper conditions for continuous complete combustion
Mix fuel with air and ignite
Separate ash from coal
Maintain heat supply to prepare and ignite the incoming fuel
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
The high steam and low water safety valve is not used in
Cochran boiler
Cornish boiler
Lancashire boiler
Locomotive boiler
By compounding the expansion of steam in two or more cylinders, the ratio of expansion
Does not change
Increases
Decreases
None of these
Which is not correct statement about pulverised fuel firing?
High burning rate is possible
Heat release can be easily controlled
Fuel burns economically
It is the best technique for burning high ash content fuel having low fusion ash
The critical pressure at which latent heat of vaporisation is zero is
225.65 kgf/ cm²
273 kgf/ cm²
100 kgf/ cm²
1 kgf/ cm²
The velocity of whirl at outlet for an axial discharge turbine is
Minimum
Maximum
Zero
None of these
Maximum energy loss in a boiler occurs due to
Unburnt carbon in ash
Incomplete combustion
Ash content
Flue gases
The performance of a boiler is measured by the
Amount of water evaporated per hour
Steam produced in kg/h
Steam produced in kg/kg of fuel burnt
All of these
Fire tube boilers are
Internally fired
Externally fired
Internally as well as externally fired
None of these
The cylindrical shell of a Lancashire boiler has diameter from
1 to 2 m
1.25 to 2.25 m
1.5 to 2.5 m
1.75 to 2.75 m
An economiser in a boiler
Increases steam pressure
Increases steam flow
Decreases fuel consumption
Decreases steam pressure
Which is not the correct statement about moisture in coal?
Inherent moisture and surface moisture are different things
In some coals moisture may be present up to 40%
Some moisture in coal helps in better burning which is not possible with completely dry coal
It increases thermal efficiency
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
Carbonisation of coal is the process of
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
Binding the pulverised coal into briquettes
Alkaline pyrogallate is used in Orsat's apparatus for absorption of
CO₂
CO
O₂
N₂
When the cross-section of a nozzle increases continuously from entrance to exit, it is called a
Divergent nozzle
Convergent nozzle
Convergent-divergent nozzle
None of these
The basic job of feed water treatment in boilers is to overcome the problem of
Corrosion
Scale
Carryover
All of the above
The draught produced by a steam jet issuing from a nozzle placed in the chimney is called
Induced steam jet draught
Chimney draught
Forced steam jet draught
None of these
The amount of water evaporated in kg per kg of fuel burnt is called
Evaporative capacity of a boiler
Equivalent evaporation from and at 100° C
Boiler efficiency
None of these
Proximate analysis of fuel is determination of percentage of
Carbon, hydrogen, nitrogen, sulphur, moisture
Fixed carbon, ash, volatile matter, moisture
Higher calorific value
Lower calorific value
Steam in water tube boiler as compared to fire tube boiler
Can be raised rapidly
Is raised at slower rate
Is raised at same rate
Could be raised at fast/slow rate depending on design
It is required to produce large amount of steam at low pressure. Which boiler should be used?
Pulverised fuel fired boiler
Cochran boiler
Lancashire boiler
Babcock and Wilcox boiler
Feed water conditioning in thermal power plants in done to
Reduce hardness and for removal of solids
Increase efficiency of thermal power plant
Increase heat transfer rate
Increase steam parameters
The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.
Remains same
Decreases
Increases
None of these
The basic purpose of drum in boiler is to
Serve as storage of steam
Serve as storage of feed water for water wall
Remove salts from water
Separate steam from water
The diameters of fire tubes and superheater tubes in locomotive boiler are
47.5 mm, 130 mm
32.5 mm, 180 mm
65.5 mm, 210 mm
24.5 mm, 65 mm
When steam after doing work in the cylinder passes into a condenser, the engine is said to be a
Slow speed engine
Vertical steam engine
Condensing steam engine
Non-condensing steam engine
In impulse turbines, when friction is neglected, the relative velocity of steam at outlet tip of the blade is __________ the relative velocity of steam at inlet tip of the blade.
Equal to
Less than
Greater than
None of these
The diameter of Cornish boiler is of the order of
12 m
1.52.5 m
23 m
2.53.5 m