In order to obtain superheated steam, a superheater is added in an existing boiler. As as result, furnace vacuum will
Remain unaffected
Improve
Worsen
May improve/worsen depending on size
Correct Answer :
C. Worsen
Related Questions
A condenser in a steam power plant
Increases expansion ratio of steam
Reduces back pressure of steam
Reduces temperature of exhaust steam
All of these
The change in internal energy in steam engines equals to
Work done during the Rankine cycle
Work done during compression
Work done during adiabatic expansion
Change in enthalpy
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
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
The safety valve on boiler drum compared to safety valve on superheater is set at
Same value
Higher value
Lower value
Lower/higher depending on steam flow
Expansion ratio is the ratio of
Swept volume to the volume at cut-off
Clearance volume to the swept volume
Volume at cut-off to the swept volume
Swept volume to the clearance volume
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
In an impulse reaction turbine, the pressure drops gradually and continuously over
Fixed blades
Moving blades
Both fixed and moving blades
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
1 kg.m is equal to
9.81 Joules
102 Joules
427 Joules
None of these
The diagram efficiency is the ratio of
Workdone on the blades to the energy supplied to the blades
Workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
Energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
None of the above
Green coal, in order to be burnt, must be
Heated sufficiently
Burnt in excess air
Heated to its ignition point
Burnt as powder
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 effect of friction on the flow of steam through a nozzle is to
Decrease the mass flow rate and to increase the wetness of steam
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
With increase in load, convection superheater has
Drooping characteristic
Linear characteristic
Rising characteristic
Flat characteristic
In a throttling process
Heat transfer takes place
Work is done by the expanding steam
Internal energy of steam changes
None of the above
The actual vacuum in a condenser is equal to
Barometric pressure + actual pressure
Barometric pressure - actual pressure
Gauge pressure + atmospheric pressure
Gauge pressure - atmospheric pressure
The fire tubes in a Locomotive boiler has _________ diameter.
4.75 mm
5.47 mm
7.45 mm
47.5 mm
The diagram factor is the ratio of the
Area of the actual indicator diagram to the area of theoretical indicator diagram
Actual workdone per stroke to the theoretical workdone per stroke
Actual mean effective pressure to the theoretical mean effective pressure
Any one of the above
A compound steam engine in which piston rods of high pressure and low pressure cylinders ' are attached to two different cranks set at 180° to each other, is called
Receiver type compound engine
Tandem type compound engine
Woolf type compound engine
Both (A) and (B)
The ratio of the actual vacuum to the ideal vacuum in a condenser is called
Condenser efficiency
Vacuum efficiency
Nozzle efficiency
Boiler efficiency
An impulse turbine as compared to a reaction turbine, for a given power has _________ row of blades.
Equal
Less
More
None of these
The proximate analysis of fuel lists
Various chemical constituents, carbon, hydrogen, oxygen etc, plus ash as percents by volume
Various chemical constituents, carbon, hydrogen, oxygen, etc, plus ash as percents by weight
Fuel constituents as percents by volume of moisture, volatile, fixed carbon and ash
Fuel constituents as percents by weight of moisture, volatile, fixed carbon and ash
Which of the following is a fire tube boiler?
Lancashire boiler
Babcock and Wilcox boiler
Yarrow boiler
None of these
Fire tube boilers are limited to a maximum working pressure of
0.17 MN/m²
1.7 MN/m²
17 MN/m²
170 MN/m²
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
For water, at pressures below atmospheric;
Melting point rises slightly and boiling point drops markedly
Melting point rises markedly and boiling point drops markedly
Melting point drops slightly and boiling point drops markedly
Melting point drops slightly and boiling point drops slightly
Expanding steam to a very low pressure (high vacuum) in steam engines is
Desirable
Economical
Essential
Uneconomical
The ratio of the volume at cut-off to the swept volume is called
Cut-off ratio
Expansion ratio
Clearance ratio
None of these
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