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4

The three Ts for good combustion are

A. Temperature, time, and turbulence

B. Total air, true fuel, and turbulence

C. Thorough mixing, total air and temperature

D. Total air, time, and temperature

Correct Answer :

A. Temperature, time, and turbulence


Related Questions

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Cochran boiler is a

A. Horizontal fire tube boiler

B. Horizontal water tube boiler

C. Vertical water tube boiler

D. Vertical fire tube boiler

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4

The turbine blades are

A. Straight

B. Circular

C. Curved

D. None of these

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4

The density of supersaturated steam is about __________ that of the ordinary saturated vapour at the corresponding pressure.

A. Same as

B. 2 times

C. 4 times

D. 8 times

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4

The radius of a dished head is taken approximately as

A. One fourth

B. Half

C. One

D. Two

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The flow through a nozzle is regarded as

A. Constant volume flow

B. Constant pressure flow

C. Isothermal flow

D. Isentropic flow

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4

The coal requirement per kW hour generation in the thermal power plant is of the order of

A. 0.1 to 0.2 kg

B. 0.2 to 0.4 kg

C. 0.6 to 0.8 kg

D. 1.0 to 1.5 kg

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4

The isentropic enthalpy drop in moving blade is two-third of the isentropic enthalpy drop in fixed blades of a turbine. The degree of reaction will be

A. 0.4

B. 0.56

C. 0.67

D. 1.67

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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

Lancashire boiler is used where working pressure and power required are

A. Low

B. Moderate

C. High

D. None of these

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4

Which of the following is a water tube boiler?

A. Locomotive boiler

B. Cochran boiler

C. Cornish boiler

D. Babcock and Wilcox boiler

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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 function of a safety valve is

A. To blow off steam when the pressure of steam inside the boiler exceeds the working pressure

B. To indicate the water level inside the boiler to an observer

C. To measure pressure of steam inside the steam boiler

D. None of the above

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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 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 maximum discharge through a chimney occurs when the height of chimney is

A. Infinitely long

B. Around 200 meters

C. Equal to the height of the hot gas column producing draught

D. Outside temperature is very low

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4

Which of the following statement is correct?

A. A fire tube boiler occupies less space than a water tube boiler, for a given power.

B. Steam at a high pressure and in large quantities can be produced with a simple vertical boiler.

C. A simple vertical boiler has one fire tube.

D. All of the above

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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

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

The change in internal energy in steam engines equals to

A. Work done during the Rankine cycle

B. Work done during compression

C. Work done during adiabatic expansion

D. Change in enthalpy

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4

The stage efficiency (ηS) is given by (where ηB = Blading efficiency, and ηN = Nozzle efficiency)

A. ηS = ηB × ηN

B. ηS = ηB / ηN

C. ηS = ηN / ηB

D. None of these

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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

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4

The reheat factor is the ratio of the

A. Cumulative heat drop to the isentropic heat drop

B. Isentropic heat drop to the heat supplied

C. Total useful heat drop to the total isentropic heat drop

D. None of the above

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4

Expansion ratio is the ratio of

A. Swept volume to the volume at cut-off

B. Clearance volume to the swept volume

C. Volume at cut-off to the swept volume

D. Swept volume to the clearance volume

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4

The natural draught is produced by

A. Steam jet

B. Centrifugal fan

C. Chimney

D. Both (A) and (B)

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4

The efficiency of reaction turbine is maximum when (where α = Angle made by the absolute velocity V at inlet)

A. Vb = 0.5 V cosα

B. Vb = V cos α

C. Vb = 0.5 V² cosα

D. Vb = V² cosα

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4

Which is not the correct statement about moisture in coal?

A. Inherent moisture and surface moisture are different things

B. In some coals moisture may be present up to 40%

C. Some moisture in coal helps in better burning which is not possible with completely dry coal

D. It increases thermal efficiency

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4

The basic job of feed water treatment in boilers is to overcome the problem of

A. Corrosion

B. Scale

C. Carryover

D. All of the above

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4

Sublimation region is the region where

A. Solid and vapour phases are in equilibrium

B. Solid and liquid phases are in equilibrium

C. Liquid and vapour phases are in equilibrium

D. Solid, liquid and vapour phases are in equilibrium

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4

Blow off cock in a boiler is used to

A. Control the flow of steam from the boiler to the main pipe and to shut off the steam completely when required

B. Empty the boiler when required and to discharge the mud, scale or sediments which are accumulated at the bottom of the boiler

C. Put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit

D. Increase the temperature of saturated steam without raising its pressure

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4

The maximum discharge of steam through a convergent-divergent nozzle depends upon

A. Area of nozzle at throat

B. Initial pressure and volume of steam

C. Final pressure of steam leaving the nozzle

D. Both (A) and (B)