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4

Secondary air is the air used to

A. Provide air around burners for obtaining optimum combustion

B. Transport and dry the coal

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

D. Air delivered by induced draft fan

Correct Answer :

A. Provide air around burners for obtaining optimum combustion


Related Questions

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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

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4

Which of the following statement is wrong?

A. The mechanical draught reduces the height of chimney.

B. The natural draught reduces the fuel consumption.

C. A balanced draught is a combination of induced and forced draught.

D. All of the above

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4

The efficiency of an impulse turbine is maximum when (where Vb = Blade speed, V = Absolute velocity of steam entering the blade, and α = Nozzle angle)

A. Vb = 0.5 V cosα

B. Vb = V cosα

C. Vb = 0.5 V² cosα

D. Vb = V² cosα

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4

Caking coals are those which

A. Form lumps or masses of coke

B. Burn freely

C. Show little or no fusing action

D. Burn completely

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4

The air pressure at the fuel bed is reduced below that of atmosphere by means of a fan placed at or near the bottom of the chimney to produce a draught. Such a draught is called

A. Natural draught

B. Induced draught

C. Forced draught

D. Balanced draught

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4

In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is

A. Low

B. Very low

C. High

D. Very high

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4

The ratio of heat actually used in producing the steam to the heat liberated in the furnace, is known as

A. Equivalent evaporation

B. Factor of evaporation

C. Boiler efficiency

D. Power of a boiler

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4

The critical pressure ratio for initially wet steam is

A. 0.546

B. 0.577

C. 0.582

D. 0.601

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4

In forced circulation steam boilers, the force is applied

A. To draw water

B. To circulate water

C. To drain off the water

D. All of these

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4

The ratio of the temperature rise of cooling water to the vacuum temperature minus inlet cooling water temperature is called

A. Condenser efficiency

B. Vacuum efficiency

C. Nozzle efficiency

D. Boiler efficiency

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4

The ratio of heat utilised to produce steam and the heat liberated in furnace is known as

A. Boiler effectiveness

B. Boiler evaporative capacity

C. Factor of evaporation

D. Boiler efficiency

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4

The efficiency of a boiler is defined as

A. Ratio of heat actually used in producing steam to the heat liberated in the furnace

B. Ratio of the mass of steam produced to the mass of total water supplied in a given time

C. Ratio of the heat liberated in the furnace to the heat actually used in producing steam

D. None of the above

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4

With increase in load, radiant superheater has

A. Drooping characteristic

B. Linear characteristic

C. Rising characteristic

D. Flat characteristic

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4

The equivalent evaporation is defined as

A. The ratio of heat actually used in producing the steam to the heat liberated in the furnace

B. The amount of water evaporated or steam produced in kg per kg of fuel burnt

C. The amount of water evaporated from and at 100°C into dry and saturated steam

D. The evaporation of 15.653 kg of water per hour from and at 100°C

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4

The critical pressure ratio is given by (where p₁ = Initial pressure of steam, and p₂ = Pressure of steam at throat or critical pressure)

A. p₁. p₂

B. p₁/p₂

C. p₂/p₁

D. p₁ + p₂

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4

The shell diameter and length of locomotive boiler are

A. 1.5 m, 4 m

B. 1.5 m, 6 m

C. 1 m, 4 m

D. 2 m, 4 m

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4

In a compound steam engine, the first stage of expansion is carried out in a high pressure cylinder whereas the last expansion is completed in low pressure cylinder. The diameter of high pressure cylinder is _________ the low pressure cylinder.

A. Equal to

B. Less than

C. More than

D. None of these

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4

Desecration of feed water is carried out because it reduces

A. Cavitation of boiler feed pumps

B. Corrosion caused by oxygen

C. Heat transfer coefficient

D. pH value of water

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4

The velocity of steam leaving the nozzle (V) is given by (where K = Nozzle coefficient or nozzle efficiency, and hd = Enthalpy or heat drop during expansion of steam in a nozzle)

A. V = 44.72 hd K

B. V = 44.72 K hd

C. V = 44.72 K hd

D. V = 44.72 K hd

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4

The fittings mounted on the boiler for its proper and safe functioning is a

A. Water level indicator

B. Pressure gauge

C. Safety valve

D. All of these

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4

The maximum efficiency of a reaction turbine is

A. 2 sin²α/(1 + sin²α)

B. 2 cos²α/(1 + cos²α)

C. (1 + sin²α)/2 sin²α

D. (1 + cos²α)/2 cos²α

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4

Fire tube boilers are limited to a maximum design working pressure of

A. 1 kg/cm

B. 6 kg/cm

C. 17 kg/cm²

D. 100 kg/cm²

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4

The amount of water evaporated from feed water at _________ into dry and saturated steam at 100° C at normal atmospheric pressure is called equivalent evaporation from and at 100° C.

A. 0°C

B. 40°C

C. 60°C

D. 100°C

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4

One kilowatt-hour energy is equivalent to

A. 1000 J

B. 360 kJ

C. 3600 kJ

D. 3600 kW/sec

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4

In a boiler, the heat is lost

A. To dry flue gases

B. In moisture present in the fuel

C. To steam formed by combustion of hydrogen per kg of fuel

D. All of the above

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4

The flow of steam is supersonic

A. At the entrance to the nozzle

B. At the throat of the nozzle

C. In the convergent portion of the nozzle

D. In the divergent portion of the nozzle

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4

The object of producing draught in a boiler is

A. To provide an adequate supply of air for the fuel combustion

B. To exhaust the gases of combustion from the combustion chamber

C. To discharge the gases of combustion to the atmosphere through the chimney

D. All of the above

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4

A compound steam engine in which piston rods of high pressure and low pressure cylinders are attached to two different cranks set at 90° to each other, is called

A. Receiver type compound engine

B. Tandem type compound engine

C. Woolf type compound engine

D. Both (A) and (B)

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4

The function of injector used in small steam plants is to

A. Create vacuum in furnace

B. Create vacuum at turbine exhaust

C. Pump feed water

D. Dose chemicals in feed water

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4

The increase in pressure

A. Lowers the boiling point of a liquid

B. Raises the boiling point of a liquid

C. Does not affects the boiling point of a liquid

D. Reduces its volume