Fuels and Combustion Quiz 1

1 / 50

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

2 / 50

A coal containing high amount of volatile matter will have___________?

Very little ash content

High fusion point of its ash

Low adiabatic flame temperature

Low ignition temperature

3 / 50

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

Caking capacity

Inherent moisture content

Volatile matter content

Fusion point of its ash

4 / 50

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

Carbon monoxide

Methane

Acetylene

Hydrogen

5 / 50

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

Bulk density

Reactivity

Porosity

Hardness & strength

6 / 50

Anthracite can be used for_____?

Recarbonising steel

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

All A., B. and C.

7 / 50

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

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

None of these

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

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

8 / 50

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

Hydrocarbons

Oxygen

Hydrogen

Carbon monoxide

9 / 50

A coal that softens and fuses on heating is__________?

Non-caking

Carbonised

Caking

Classified

10 / 50

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

100

11 / 50

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

12 / 50

A coal having high amount of volatile matter______?

Produces very little of tar and gas on carbonisation

Ignites easily and burns with long smoky flame

Would require smaller combustion chamber

All A., B. and C.

13 / 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

14 / 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

Lower carbon dioxide content

Higher carbon monoxide content

Higher methane content and thus higher calorific value

15 / 50

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

Calorific value

Ignition temperature

Ash fusion temperature

Caking index

16 / 50

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

Nuclear fusion

All A., B. & C.

Combustion

Nuclear fission

17 / 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

Is more difficult to ignite and produces a shorter flame

Is less liable to spontaneous combustion on storage

Requires smaller combustion space and less secondary air

18 / 50

A coal having high volatile matter content will _________?

Have a very high calorific value

Give less yield of tar and gas on carbonisation

None of these

Burn with a small non-smoky flame

19 / 50

__________ is used as jet engine fuel ?

Petrol

LPG

Diesel

Kerosene

20 / 50

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

Lurgi

Fischer-Tropsch

Bergius

None of these

21 / 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

22 / 50

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

Gives smokeless burning

Shows little or no fusing action

Burns completely

None of these

23 / 50

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

Variation in the pitch of the fan blades

Damper

All A., B. and C.

Speed of the fan

24 / 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 : 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 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

25 / 50

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

> 280

300-600

> 120

< 120

26 / 50

A coal with high ash content_____?

Is not subjected to washing

Has higher calorific value

Is harder and stronger

Has low quantity of mineral matter

27 / 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

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

All A., B. and C.

28 / 50

?Wobbe index? is a characteristic of___________?

Liquid fuels

Solid fuels

Fat coals

Gaseous fuels

29 / 50

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

Neither A. nor B.

Always loss of heat from the flame

No possibility of obtaining complete combustion at high temperature

Both A. and B.

30 / 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

Low calorific value of the fuel

Presence of large quantity of hydrogen in the fuel

High sulphur content in the fuel

31 / 50

A good quality coal should have _____?

High ash content

High sulphur

None of these

Low fusion point of ash

32 / 50

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

Air

Fuel

Neither A. nor B.

Both A. & B.

33 / 50

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

Calorific value

Proximate analysis

Caking index

Ultimate analysis

34 / 50

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

Supply of excess fuel

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

Supply of excess air

None of these

35 / 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

36 / 50

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

Hydrogen

Nitrogen

Fixed carbon

Total carbon

37 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low flash point

High cost & availability

Low calorific value

Low octane number

38 / 50

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

2.5

14.5

10.5

7.5

39 / 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

40 / 50

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

Complete combustion of fuel has taken place

21% excess oxygen has been used for combustion

21% excess air has been used for combustion

No excess air has been used for combustion

41 / 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

Less

Data insufficient; can?t be predicted

42 / 50

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

Caking

High ash

Non-caking

Pulverised

43 / 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?

1 to 2

3 to 4

5 to 15

20 to 40

44 / 50

?Fat? coal means a coal having _____?

High volatile matter

Low ash content

Non smoking tendency

Low calorific value

45 / 50

Advantages of fluidised bed combustion are ______?

All A., B. & C.

Lower furnace operating temperature

High heat transfer rate

Reduced NOx formation in flue gas

46 / 50

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

Carburetted water gas

Coke oven gas

LPG

Gobar gas

47 / 50

A fuel with high heat release rate will__________?

Have high adiabatic flame temperature

None of these

Require smaller combustion chamber

Have high calorific value

48 / 50

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

Ash

Fixed carbon

Volatile matter

Oxygen

49 / 50

A good coking coal should have high _______ content?

Ash

Moisture

None of these

Sulphur & phosphorus

50 / 50

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

Boghead

Non-banded

Splint

Bright

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