Fuels and Combustion Quiz 1

1 / 50

Artificial draught produced by a fan can be controlled by the_____?

Damper

Variation in the pitch of the fan blades

All A., B. and C.

Speed of the fan

2 / 50

A fuel with high heat release rate will__________?

Have high adiabatic flame temperature

Require smaller combustion chamber

Have high calorific value

None of these

3 / 50

______ of the coal is the basis for Seylor?s coal classification?

Ultimate analysis

Proximate analysis

Caking index

Calorific value

4 / 50

?Fat coals? are those coals which have very high______?

Inherent moisture content

Fusion point of its ash

Volatile matter content

Caking capacity

5 / 50

?Wobbe index? is a characteristic of___________?

Liquid fuels

Gaseous fuels

Fat coals

Solid fuels

6 / 50

A coal having higher volatile matter content will necessarily have lower______?

Caking index

Ignition temperature

Calorific value

Ash fusion temperature

7 / 50

Actual flame temperature is always lower than the adiabatic flame temperature, because there is_________?

Neither A. nor B.

No possibility of obtaining complete combustion at high temperature

Always loss of heat from the flame

Both A. and B.

8 / 50

A certain thickness of the coal, if stored unscientifically on soft (katcha) ground having no metallic/concrete flooring gets sunked into the ground, which is termed as the ?carpet loss?. The carpet loss may be of the order of _______ cms?

5 to 15

20 to 40

1 to 2

3 to 4

9 / 50

A coal with high ash content is undesirable, as_________?

All A., B. and C.

The ash retains the sulphur & phosphorus and thus affects the quality of products in metallurgical furnace apart from increasing the slag volume. Besides, it may fuse and stick to the boiler tubes thereby reducing the heat transfer

It is abrasive to the coal pulveriser (i.e. ball mill) and the combustion chamber

The ash in molten condition gets absorbed in the pores of the refractory lining of the furnace and causes its spalling due to different co-efficient of expansion/contraction of the refractory and the ash

10 / 50

A coal with high ______ content, would ignite most easily?

Volatile matter

Oxygen

Ash

Fixed carbon

11 / 50

?Wind loss? resulting from unscientific storage of coal may be the order of about ______ percent?

10.5

14.5

2.5

7.5

12 / 50

(64-132) rank coal (ASTM) means a coal with 64%_____?

Fixed carbon and a heating value of 132 BTU/1b

Fixed carbon and having a heat value of 13, 200 BTU/1b

Ash and a heating value of 13, 200 BTU/1b

None of these

13 / 50

64-132) rank coal (ASTM) means a coal with 64%_____?

Ash and heating value around 13, 200 BTU/1b

None of these

Fixed carbon and heating value around 132 BTU/1b

Fixed carbon and having a heating value around 13, 200 BTU/1b

14 / 50

A liquid/gaseous fuel containing hydrocarbons and high amount of sulphur is burnt with 40% excess air. The flue gas still contains large amount of carbon monoxide. This may be due to the__________?

Lack of thorough mixing of fuel with air

High sulphur content in the fuel

Low calorific value of the fuel

Presence of large quantity of hydrogen in the fuel

15 / 50

A coal that softens and fuses on heating is__________?

Caking

Non-caking

Carbonised

Classified

16 / 50

A good coking coal should have high _______ content?

Ash

None of these

Moisture

Sulphur & phosphorus

17 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low flash point

High cost & availability

Low calorific value

Low octane number

18 / 50

About ______ Nm3 of air will be required for the complete combustion of 2Nm3 of CO?

19 / 50

______ present in coal is not determined in its ultimate analysis ?

Hydrogen

Total carbon

Fixed carbon

Nitrogen

20 / 50

A coal having high volatile matter content will _________?

Have a very high calorific value

Burn with a small non-smoky flame

None of these

Give less yield of tar and gas on carbonisation

21 / 50

Anthracite coal ______?

Burns with short, bluish, yellow-tipped flame producing very little smoke

Ignites more easily than bituminous coal

Contains more volatile matter than bituminous coal

Is essentially a coking coal

22 / 50

A good quality coal should have _____?

High sulphur

Low fusion point of ash

None of these

High ash content

23 / 50

A particular coal is said to be free burning when it ___________?

Shows little or no fusing action

Gives smokeless burning

None of these

Burns completely

24 / 50

A coal having higher volatile matter content, has lower__________?

Ignition temperature

Smoking tendency on burning

Chance of catching fire during storage in open space

Coke oven gas yield on carbonisation

25 / 50

?Micum Index? of a coke is a measure of its_____?

Porosity

Hardness & strength

Bulk density

Reactivity

26 / 50

A gaseous fuel in order to develop luminosity on burning, must contain ___________?

Hydrocarbons

Oxygen

Hydrogen

Carbon monoxide

27 / 50

?Overfire burning? in a furnace is a phenomenon characterised by the ___________?

Burning of carbon monoxide and other incombustibles in upper zone of furnace by supplying more air

Supply of excess fuel

Supply of excess air

None of these

28 / 50

______ has the widest inflammability limit (explosion limit) of all the gases?

Methane

Hydrogen

Acetylene

Carbon monoxide

29 / 50

A coal having high ratio of volatile matter to fixed carbon as compared to a coal having low ratio of volatile matter to fixed carbon __________?

None of these

Requires smaller combustion space and less secondary air

Is more difficult to ignite and produces a shorter flame

Is less liable to spontaneous combustion on storage

30 / 50

A carbonaceous fuel (containing no H2 or hydrocarbons) is burnt and the resulting flue gas contains 21% CO2. It means that_____?

21% excess air has been used for combustion

21% excess oxygen has been used for combustion

Complete combustion of fuel has taken place

No excess air has been used for combustion

31 / 50

?Fat? coal means a coal having _____?

High volatile matter

Low calorific value

Low ash content

Non smoking tendency

32 / 50

Advantages of fluidised bed combustion are ______?

Lower furnace operating temperature

High heat transfer rate

Reduced NOx formation in flue gas

All A., B. & C.

33 / 50

A good metallurgical coke_____?

Should be brittle

Must contain moderate quantities of ash, moisture, sulphur and volatile matters

Should have low fusion point of its ash

Should have high porosity

34 / 50

A sample of natural gas containing 80% methane (CH4) and rest nitrogen (N2) is burnt with 20% excess air. With 80% of the combustibles producing CO2 and the remainder going to CO, the Orsat analysis in volume percent is__________?

CO2 : 6.39, CO : 1.60, O2 : 3.99, H2O:25.96, N2:72.06

CO2 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

CO2 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60

CO2 : 7.42, CO : 1.86, O2 : 4.64, N2:86.02

35 / 50

__________ is used as jet engine fuel ?

Kerosene

Petrol

LPG

Diesel

36 / 50

Abel apparatus is used for those oils, whose flash points are ___________?F?

> 280

300-600

> 120

< 120

37 / 50

Abrasion index of blast furnace coke should be around ______ percent?

38 / 50

_____ process is meant for direct hydrogenation of coal to produce liquid fuel?

None of these

Lurgi

Bergius

Fischer-Tropsch

39 / 50

Adiabatic flame temperature of a fuel is dependent on the initial temperature of_____?

Air

Both A. & B.

Neither A. nor B.

Fuel

40 / 50

?Fuel? can be defined as a substance which produces heat by_____?

Combustion

All A., B. & C.

Nuclear fission

Nuclear fusion

41 / 50

Air/gas ratio for complete combustion will be the highest for___________?

Coke oven gas

LPG

Carburetted water gas

Gobar gas

42 / 50

Ammonia content in raw coke oven gas is about ______ gm/Nm3?

100

43 / 50

Anthracite can be used for_____?

Blending with highly coking coal to check its swelling which helps in saving coke even walls from damage and to produce high strength coke

Making carbon electrodes

Recarbonising steel

All A., B. and C.

44 / 50

A coal containing high amount of volatile matter will have___________?

Low adiabatic flame temperature

Low ignition temperature

High fusion point of its ash

Very little ash content

45 / 50

A coal with high ash content_____?

Has low quantity of mineral matter

Is not subjected to washing

Has higher calorific value

Is harder and stronger

46 / 50

A coal gasifier operating at 20 atm. (e.g. Lurgi gasifier) as compared to one operating at atmospheric pressure (e.g. Kopper-Totzek or Winkler gasifier) will produce a gas having _______?

None of these

Higher carbon monoxide content

Higher methane content and thus higher calorific value

Lower carbon dioxide content

47 / 50

A fuel containing carbon and carbon monoxide (but containing no hydrogen or its compounds) is burnt in pure oxygen at constant pressure. Its gross calorific value as compared to net calorific value will be__________?

Same

Data insufficient; can?t be predicted

Less

48 / 50

A travelling grate stoker is meant for the efficient burning of _______ coal?

Non-caking

Pulverised

Caking

High ash

49 / 50

A coal having high amount of volatile matter______?

Produces very little of tar and gas on carbonisation

Would require smaller combustion chamber

Ignites easily and burns with long smoky flame

All A., B. and C.

50 / 50

A coal containing very high percentage of durain is called _______ coal?

Splint

Bright

Boghead

Non-banded

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