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4

For maximum discharge through a chimney, the condition is that height of hot gas column producing the draught should be

A. One-half the height of chimney

B. Equal to the height of chimney

C. Two times the height of chimney

D. Four times the height of chimney

Correct Answer :

B. Equal to the height of chimney


Related Questions

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4

Water tube boilers are those in which

A. Flue gases pass through tubes and water around it

B. Water passes through the tubes and flue gases around it

C. Work is done during adiabatic expansion

D. Change in enthalpy

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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

The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ numbers of stages are required.

A. More

B. Less

C. Equal

D. None of these

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4

Reheating of steam under ideal conditions takes place at constant

A. Entropy

B. Enthalpy

C. Pressure

D. Temperature

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The major axis of elliptical manholes on the shell should be provided

A. Longitudinally

B. Circumferentially

C. On dished end

D. Anywhere

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4

Water tube boilers are

A. Internally fired

B. Externally fired

C. Internally as well as externally fired

D. None of these

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4

In water wall furnace, the heat is transferred to the water walls by

A. Convection

B. Radiation

C. Conduction

D. Radiation and conduction

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4

The critical pressure ratio (p₂/p₁) is given by

A. (p₂/p₁) = [2/(n - 1)] n/(n + 1)

B. (p₂/p₁) = [2/(n + 1)] n/(n-1)

C. (p₂/p₁) = [(n - 1)/2] n + (1/n)

D. (p₂/p₁) = [(n + 1)/2] n - (1/n)

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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

The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is

A. Less

B. More

C. Equal

D. May be less or more depending on temperature

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4

The action of steam in a steam turbine is

A. Static

B. Dynamic

C. Static and dynamic

D. Neither static nor dynamic

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Fire tube boilers are

A. Internally fired

B. Externally fired

C. Internally as well as externally fired

D. None of these

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4

When the inlet pressure of steam is equal to the exit pressure, then

A. There is a pressure drop in the nozzle

B. Fluid flows through the nozzle

C. Pressure drops and fluid flows through the nozzle

D. There is no pressure drop and fluid does not flow through the nozzle

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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

When the circulation of water, in a boiler, is by convection currents which are set up during the heating of water, then the boiler is known as

A. Internally fired boiler

B. Externally fired boiler

C. Natural circulation boiler

D. Forced circulation boiler

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4

The diameter of a cylindrical shell of a Scotch marine boiler varies from

A. 1.5 to 2 m

B. 2.5 to 3.5 m

C. 3.5 to 4.5 m

D. None of these

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4

The crown of the fire box is made hemispherical in order to

A. Give maximum space

B. Give maximum strength

C. Withstand pressure inside boiler

D. Resist intense heat in fire box

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4

The shell of the Cochran boiler is made hemispherical

A. To give maximum space and strength

B. To withstand the pressure of steam inside the boiler

C. Both (A) and (B)

D. None of the above

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4

Fire tube boilers are limited to a maximum working pressure of

A. 0.17 MN/m²

B. 1.7 MN/m²

C. 17 MN/m²

D. 170 MN/m²

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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 rate of steam produced in Benson boiler is

A. 100 tonnes/h

B. 135 tonnes/h

C. 175 tonnes/h

D. 250 tonnes/h

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The draught (in mm of water), for maximum discharge of flue gases through the chimney, is given by (where H = Height of the chimney in metres, and T1 = Absolute temperature of air outside the chimney in K)

A. T1 /88.25H

B. 88.25H/T1

C. T1 /176.5H

D. 176.5H/T1

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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

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O₂ content in atmospheric air on weight basis is

A. 21 %

B. 23 %

C. 30 %

D. 40 %

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4

Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler

A. Increases

B. Decreases

C. Remain unaffected

D. First increases and then decreases

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4

The ultimate analysis of fuel lists

A. Various chemical constituents, carbon, hydrogen, oxygen etc, plus ash as percents by volume

B. Various chemical constituents, carbon, hydrogen, oxygen, etc, plus ash as percents by weight

C. Fuel constituents as percents by volume of moisture, volatile, fixed carbon and ash

D. Fuel constituents as percents by weight of moisture, volatile, fixed carbon and ash

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Sulphur content of fuels is very important to the plant operators because it

A. Has high heating value

B. Retards electric precipitation

C. Promotes complete combustion

D. Has highly corrosive effect

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4

The overall efficiency of thermal power plant is

A. Boiler efficiency, turbine efficiency, generator efficiency

B. All the three above plus gas cycle efficiency

C. Carnot cycle efficiency

D. Regenerative cycle efficiency

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4

The diagram factor is the ratio of the

A. Area of the actual indicator diagram to the area of theoretical indicator diagram

B. Actual workdone per stroke to the theoretical workdone per stroke

C. Actual mean effective pressure to the theoretical mean effective pressure

D. Any one of the above

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4

In a boiler, feed water supplied per hour is 205 kg while coal fired per hour is 23 kg. The net enthalpy rise per kg of water is 145 kJ. If the calorific valve of the coal is 2050 kJ/kg, then the boiler efficiency will be

A. 56 %

B. 63 %

C. 74 %

D. 78 %