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4

The fire tubes in a Cochran boiler usually have _________ diameter.

A. 6.25 mm

B. 62.5 mm

C. 72.5 mm

D. 92.5 mm

Correct Answer :

B. 62.5 mm


Related Questions

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4

In a Parson's turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be

A. 160/3 m/s

B. 320/3 m/s

C. 640/3 m/s

D. 640 m/s

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4

Lancashire boiler is

A. Stationary fire tube boiler

B. Internally fired boiler

C. Horizontal boiler

D. All of these

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4

A stage, in reaction turbine, is represented by

A. Number of casing

B. Number of entries of steam

C. Number of exits of steam

D. Each row of blades

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4

The function of a piston in a steam engine is

A. To guide motion of the piston rod and to prevent it from bending

B. To transfer motion from the piston to the crosshead

C. To convert heat energy of the steam into mechanical work id) to exhaust steam from the cylinder at proper moment

D. None of these

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4

The diameters of fire tubes and superheater tubes in locomotive boiler are

A. 47.5 mm, 130 mm

B. 32.5 mm, 180 mm

C. 65.5 mm, 210 mm

D. 24.5 mm, 65 mm

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4

Heating of dry steam above saturation temperature is known as

A. Enthalpy

B. Superheating

C. Super saturation

D. Latent heat

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4

The draught produced by a steam jet issuing from a nozzle placed in the ash-pit under the fire grate of the furnace is called

A. Induced steam jet draught

B. Chimney draught

C. Forced steam jet draught

D. None of these

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4

An air preheater

A. Increases evaporative capacity of the boiler

B. Increases the efficiency of the boiler

C. Enables low grade fuel to be burnt

D. All of the above

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4

Efficiency of a thermal cycle increases by

A. Regeneration

B. Reheating of steam

C. Both (A) and (B)

D. Cooling of steam

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4

The supersaturated flow of steam through a nozzle as compared to a stable flow, the available heat drop

A. Remains the same

B. Increases

C. Decreases

D. Is unpredictable

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4

The theoretical indicator diagram of a simple steam engine is based upon the assumption that

A. There is no pressure drop due to condensation

B. Steam is admitted at boiler pressure and exhausted at condenser pressure

C. The expansion (or compression) of the steam is hyperbolic

D. All of the above

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4

The main object of a boiler trial is

A. To determine the generating capacity of the boiler

B. To determine the thermal efficiency of the boiler when working at a definite pressure

C. To prepare heat balance sheet for the boiler

D. All of the above

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4

The length of shell of a Locomotive boiler is

A. 1 m

B. 2 m

C. 3 m

D. 4 m

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4

All steam engines work on

A. Zeroth law of thermodynamics

B. First law of thermodynamics

C. Second law of thermodynamics

D. None of these

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4

The ratio of the workdone on the blades to the energy supplied to the blades, is called

A. Blading efficiency

B. Nozzle efficiency

C. Gross or stage efficiency

D. Mechanical efficiency

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4

A wet vapour can be completely specified by

A. Pressure only

B. Temperature only

C. Dryness fraction only

D. Pressure and dryness fraction

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4

Superheating of steam is done at

A. Constant volume

B. Constant temperature

C. Constant pressure

D. Constant entropy

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4

Bomb calorimeter is used to determine

A. Higher calorific value at constant volume

B. Lower calorific value at constant volume

C. Higher calorific value at constant pressure

D. Lower calorific value at constant pressure

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4

In recuperative air preheaters, the heat is transferred

A. From a metal wall from one medium to another

B. From heating an intermediate material and then heating the air from this material

C. By direct mixing,

D. Heat is transferred by bleeding some gases from furnace

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4

1 kg.m is equal to

A. 9.81 Joules

B. 102 Joules

C. 427 Joules

D. None of these

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4

Tertiary air is the air used to

A. Provide air around burners for obtaining optimum combustion

B. Transport and dry the coal

C. Cool the scanners

D. Convert CO (formed in lower zone of furnace) into CO₂ at higher zone.

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4

The dry saturated steam at very high pressure (150200 kg/cm²) when throttled to atmosphere will become

A. Wet

B. Superheated

C. Remain dry saturated

D. Dry

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4

Spontaneous combustion is a phenomenon in which

A. All the fuel burns instantaneously producing high energy release

B. Fuel burns with less air

C. Coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal

D. Explosion in furnace

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4

Carbonisation of coal is the process of

A. Pulverising coal in inert atmosphere

B. Heating wood in a limited supply of air at temperatures below 300°C

C. Strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel

D. Binding the pulverised coal into briquettes

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4

Boiler parameters are expressed by

A. Tonnes/hr. of steam

B. Pressure of steam in kg/cm²

C. Temperature of steam in °C

D. All of the above

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4

The economiser is used in boilers to

A. Increase thermal efficiency of boiler

B. Economise on fuel

C. Extract heat from the exhaust flue gases

D. Increase flue gas temperature

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4

One kg of steam sample contains 0.8 kg dry steam; Its dryness fraction is

A. 0.2

B. 0.8

C. 1.0

D. 0.6

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4

By compounding the expansion of steam in two or more cylinders, the length of stroke

A. Does not change

B. Increases

C. Decreases

D. None of these

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4

The function of an eccentric rod is

A. To provide reciprocating motion to the slide valve

B. To convert reciprocating motion of the piston into rotary motion of the crank

C. To convert rotary motion of the crankshaft into to and fro motion of the valve rod

D. To provide simple harmonic motion to the D-slide valve

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4

The pressure of feed water has to be raised before its entry into the boiler. The pressure is raised by a device known as

A. Feed pump

B. Injector

C. Feed check valve

D. Pressure gauge