Fuels and Combustion Quiz 1

1 / 50

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

Carbon monoxide

Methane

Acetylene

Hydrogen

2 / 50

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

Inherent moisture content

Volatile matter content

Fusion point of its ash

Caking capacity

3 / 50

A good quality coal should have _____?

High ash content

Low fusion point of ash

High sulphur

None of these

4 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low calorific value

Low octane number

Low flash point

High cost & availability

5 / 50

A fuel with high heat release rate will__________?

Have high calorific value

None of these

Have high adiabatic flame temperature

Require smaller combustion chamber

6 / 50

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

Porosity

Reactivity

Hardness & strength

Bulk density

7 / 50

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

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

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

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

None of these

8 / 50

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

21% excess oxygen has been used for combustion

Complete combustion of fuel has taken place

No excess air has been used for combustion

21% excess air has been used for combustion

9 / 50

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

> 120

> 280

300-600

< 120

10 / 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?

20 to 40

1 to 2

5 to 15

3 to 4

11 / 50

A good metallurgical coke_____?

Should have high porosity

Should be brittle

Should have low fusion point of its ash

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

12 / 50

?Wobbe index? is a characteristic of___________?

Solid fuels

Fat coals

Liquid fuels

Gaseous fuels

13 / 50

A coal containing high amount of volatile matter will have___________?

Low ignition temperature

Very little ash content

High fusion point of its ash

Low adiabatic flame temperature

14 / 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__________?

Data insufficient; can?t be predicted

Less

Same

15 / 50

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

7.5

10.5

14.5

2.5

16 / 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 __________?

Is less liable to spontaneous combustion on storage

Is more difficult to ignite and produces a shorter flame

Requires smaller combustion space and less secondary air

None of these

17 / 50

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

Caking index

Ultimate analysis

Proximate analysis

Calorific value

18 / 50

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

Combustion

Nuclear fission

All A., B. & C.

Nuclear fusion

19 / 50

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

Caking index

Ignition temperature

Ash fusion temperature

Calorific value

20 / 50

__________ is used as jet engine fuel ?

LPG

Diesel

Petrol

Kerosene

21 / 50

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

Total carbon

Nitrogen

Hydrogen

Fixed carbon

22 / 50

A coal with high ash content_____?

Is harder and stronger

Has low quantity of mineral matter

Is not subjected to washing

Has higher calorific value

23 / 50

Anthracite coal ______?

Ignites more easily than bituminous coal

Is essentially a coking coal

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

Contains more volatile matter than bituminous coal

24 / 50

A coal with high ash content is undesirable, as_________?

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

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

All A., B. and C.

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

25 / 50

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

Neither A. nor B.

Both A. & B.

Air

Fuel

26 / 50

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

Both A. and B.

Neither A. nor B.

Always loss of heat from the flame

No possibility of obtaining complete combustion at high temperature

27 / 50

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

28 / 50

A good coking coal should have high _______ content?

Moisture

None of these

Sulphur & phosphorus

Ash

29 / 50

A coal having high volatile matter content will _________?

Give less yield of tar and gas on carbonisation

Have a very high calorific value

None of these

Burn with a small non-smoky flame

30 / 50

Advantages of fluidised bed combustion are ______?

All A., B. & C.

High heat transfer rate

Lower furnace operating temperature

Reduced NOx formation in flue gas

31 / 50

A coal that softens and fuses on heating is__________?

Caking

Carbonised

Non-caking

Classified

32 / 50

Anthracite can be used for_____?

All A., B. and C.

Recarbonising steel

Making carbon electrodes

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

33 / 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

34 / 50

?Fat? coal means a coal having _____?

Low calorific value

Low ash content

High volatile matter

Non smoking tendency

35 / 50

A coal having high amount of volatile matter______?

Would require smaller combustion chamber

Produces very little of tar and gas on carbonisation

Ignites easily and burns with long smoky flame

All A., B. and C.

36 / 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__________?

High sulphur content in the fuel

Low calorific value of the fuel

Presence of large quantity of hydrogen in the fuel

Lack of thorough mixing of fuel with air

37 / 50

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

Supply of excess air

None of these

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

Supply of excess fuel

38 / 50

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

Splint

Non-banded

Boghead

Bright

39 / 50

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

Volatile matter

Ash

Fixed carbon

Oxygen

40 / 50

A coal having higher volatile matter content, has lower__________?

Chance of catching fire during storage in open space

Smoking tendency on burning

Ignition temperature

Coke oven gas yield on carbonisation

41 / 50

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

None of these

Shows little or no fusing action

Burns completely

Gives smokeless burning

42 / 50

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

43 / 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 _______?

Higher methane content and thus higher calorific value

None of these

Lower carbon dioxide content

Higher carbon monoxide content

44 / 50

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

100

45 / 50

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

Gobar gas

LPG

Carburetted water gas

Coke oven gas

46 / 50

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

Lurgi

None of these

Bergius

Fischer-Tropsch

47 / 50

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

Pulverised

Caking

High ash

Non-caking

48 / 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 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60

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

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

49 / 50

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

Hydrogen

Carbon monoxide

Oxygen

Hydrocarbons

50 / 50

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

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

Fixed carbon and heating value around 132 BTU/1b

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

None of these

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