Fuels and Combustion Quiz 1

1 / 50

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

Reactivity

Bulk density

Porosity

Hardness & strength

2 / 50

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

No excess air has been used for combustion

21% excess oxygen has been used for combustion

Complete combustion of fuel has taken place

21% excess air has been used for combustion

3 / 50

A coal having high amount of volatile matter______?

Would require smaller combustion chamber

Ignites easily and burns with long smoky flame

Produces very little of tar and gas on carbonisation

All A., B. and C.

4 / 50

Anthracite coal ______?

Contains more volatile matter than bituminous coal

Is essentially a coking coal

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

Ignites more easily than bituminous coal

5 / 50

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

Air

Both A. & B.

Neither A. nor B.

Fuel

6 / 50

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

Caking capacity

Volatile matter content

Fusion point of its ash

Inherent moisture content

7 / 50

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

100

8 / 50

A good metallurgical coke_____?

Should be brittle

Should have high porosity

Should have low fusion point of its ash

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

9 / 50

A coal that softens and fuses on heating is__________?

Caking

Non-caking

Carbonised

Classified

10 / 50

?Wobbe index? is a characteristic of___________?

Fat coals

Liquid fuels

Solid fuels

Gaseous fuels

11 / 50

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

Coke oven gas

Carburetted water gas

Gobar gas

LPG

12 / 50

A coal having high volatile matter content will _________?

Give less yield of tar and gas on carbonisation

None of these

Have a very high calorific value

Burn with a small non-smoky flame

13 / 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 : 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

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

14 / 50

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

None of these

Supply of excess air

Supply of excess fuel

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

15 / 50

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

16 / 50

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

Non-banded

Boghead

Splint

Bright

17 / 50

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

Both A. and B.

Always loss of heat from the flame

Neither A. nor B.

No possibility of obtaining complete combustion at high temperature

18 / 50

A fuel with high heat release rate will__________?

None of these

Have high calorific value

Require smaller combustion chamber

Have high adiabatic flame temperature

19 / 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

Same

Less

20 / 50

?Fat? coal means a coal having _____?

High volatile matter

Non smoking tendency

Low calorific value

Low ash content

21 / 50

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

Speed of the fan

Variation in the pitch of the fan blades

All A., B. and C.

Damper

22 / 50

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

Hydrocarbons

Carbon monoxide

Oxygen

Hydrogen

23 / 50

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

Hydrogen

Methane

Acetylene

Carbon monoxide

24 / 50

A coal containing high amount of volatile matter will have___________?

Very little ash content

Low adiabatic flame temperature

Low ignition temperature

High fusion point of its ash

25 / 50

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

Volatile matter

Fixed carbon

Ash

Oxygen

26 / 50

A coal with high ash content is undesirable, as_________?

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

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

All A., B. and C.

27 / 50

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

28 / 50

A coal with high ash content_____?

Has higher calorific value

Is harder and stronger

Is not subjected to washing

Has low quantity of mineral matter

29 / 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

Lack of thorough mixing of fuel with air

Presence of large quantity of hydrogen in the fuel

30 / 50

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

Fischer-Tropsch

Bergius

None of these

Lurgi

31 / 50

A good coking coal should have high _______ content?

Sulphur & phosphorus

None of these

Ash

Moisture

32 / 50

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

Calorific value

Ignition temperature

Ash fusion temperature

Caking index

33 / 50

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

Proximate analysis

Ultimate analysis

Caking index

Calorific value

34 / 50

Advantages of fluidised bed combustion are ______?

Lower furnace operating temperature

Reduced NOx formation in flue gas

All A., B. & C.

High heat transfer rate

35 / 50

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

> 120

< 120

300-600

> 280

36 / 50

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

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

Fixed carbon and heating value around 132 BTU/1b

None of these

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

37 / 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

Lower carbon dioxide content

Higher carbon monoxide content

None of these

38 / 50

__________ is used as jet engine fuel ?

Petrol

Diesel

LPG

Kerosene

39 / 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

All A., B. and C.

Recarbonising steel

40 / 50

A coal having higher volatile matter content, has lower__________?

Coke oven gas yield on carbonisation

Ignition temperature

Smoking tendency on burning

Chance of catching fire during storage in open space

41 / 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

42 / 50

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

Pulverised

Non-caking

Caking

High ash

43 / 50

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

All A., B. & C.

Nuclear fission

Combustion

Nuclear fusion

44 / 50

A good quality coal should have _____?

High sulphur

None of these

High ash content

Low fusion point of ash

45 / 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

5 to 15

3 to 4

1 to 2

46 / 50

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

10.5

14.5

2.5

7.5

47 / 50

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

Hydrogen

Total carbon

Fixed carbon

Nitrogen

48 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low calorific value

Low flash point

Low octane number

High cost & availability

49 / 50

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

Shows little or no fusing action

Burns completely

Gives smokeless burning

None of these

50 / 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

None of these

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

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