Fuels and Combustion Quiz 1

1 / 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

2 / 50

Advantages of fluidised bed combustion are ______?

All A., B. & C.

High heat transfer rate

Reduced NOx formation in flue gas

Lower furnace operating temperature

3 / 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 : 7.42, 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

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

4 / 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

Recarbonising steel

All A., B. and C.

Making carbon electrodes

5 / 50

A good coking coal should have high _______ content?

Sulphur & phosphorus

None of these

Moisture

Ash

6 / 50

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

7 / 50

A coal that softens and fuses on heating is__________?

Caking

Carbonised

Classified

Non-caking

8 / 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

9 / 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 _______?

Lower carbon dioxide content

Higher carbon monoxide content

Higher methane content and thus higher calorific value

None of these

10 / 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__________?

Low calorific value of the fuel

Lack of thorough mixing of fuel with air

Presence of large quantity of hydrogen in the fuel

High sulphur content in the fuel

11 / 50

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

Neither A. nor B.

Both A. and B.

Always loss of heat from the flame

No possibility of obtaining complete combustion at high temperature

12 / 50

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

Ash fusion temperature

Caking index

Ignition temperature

Calorific value

13 / 50

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

Caking

Non-caking

Pulverised

High ash

14 / 50

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

None of these

Burns completely

Gives smokeless burning

Shows little or no fusing action

15 / 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

16 / 50

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

Total carbon

Nitrogen

Fixed carbon

Hydrogen

17 / 50

A coal with high ash content_____?

Is not subjected to washing

Is harder and stronger

Has low quantity of mineral matter

Has higher calorific value

18 / 50

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

Reactivity

Hardness & strength

Bulk density

Porosity

19 / 50

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

Acetylene

Methane

Hydrogen

Carbon monoxide

20 / 50

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

Variation in the pitch of the fan blades

All A., B. and C.

Damper

Speed of the fan

21 / 50

A coal having high volatile matter content will _________?

None of these

Have a very high calorific value

Give less yield of tar and gas on carbonisation

Burn with a small non-smoky flame

22 / 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

No excess air has been used for combustion

Complete combustion of fuel has taken place

21% excess oxygen has been used for combustion

23 / 50

__________ is used as jet engine fuel ?

Diesel

Petrol

Kerosene

LPG

24 / 50

?Fat? coal means a coal having _____?

Low calorific value

Low ash content

High volatile matter

Non smoking tendency

25 / 50

A coal containing high amount of volatile matter will have___________?

Low adiabatic flame temperature

Very little ash content

Low ignition temperature

High fusion point of its ash

26 / 50

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

Nuclear fusion

Combustion

Nuclear fission

All A., B. & C.

27 / 50

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

> 120

> 280

< 120

300-600

28 / 50

A good metallurgical coke_____?

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

Should have low fusion point of its ash

Should be brittle

Should have high porosity

29 / 50

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

Caking capacity

Inherent moisture content

Volatile matter content

Fusion point of its ash

30 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low octane number

Low calorific value

High cost & availability

Low flash point

31 / 50

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

Oxygen

Hydrocarbons

Carbon monoxide

Hydrogen

32 / 50

A coal having high amount of volatile matter______?

Would require smaller combustion chamber

Produces very little of tar and gas on carbonisation

All A., B. and C.

Ignites easily and burns with long smoky flame

33 / 50

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

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

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

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

None of these

34 / 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

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

All A., B. and C.

35 / 50

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

Non-banded

Bright

Splint

Boghead

36 / 50

A good quality coal should have _____?

None of these

High ash content

Low fusion point of ash

High sulphur

37 / 50

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

100

38 / 50

A fuel with high heat release rate will__________?

Have high adiabatic flame temperature

Have high calorific value

None of these

Require smaller combustion chamber

39 / 50

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

LPG

Coke oven gas

Gobar gas

Carburetted water gas

40 / 50

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

Calorific value

Ultimate analysis

Caking index

Proximate analysis

41 / 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

42 / 50

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

Fischer-Tropsch

Bergius

None of these

Lurgi

43 / 50

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

44 / 50

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

None of these

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

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

Fixed carbon and heating value around 132 BTU/1b

45 / 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 less liable to spontaneous combustion on storage

Is more difficult to ignite and produces a shorter flame

46 / 50

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

Fuel

Both A. & B.

Neither A. nor B.

Air

47 / 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

1 to 2

20 to 40

3 to 4

48 / 50

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

7.5

14.5

10.5

2.5

49 / 50

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

Volatile matter

Ash

Fixed carbon

Oxygen

50 / 50

?Wobbe index? is a characteristic of___________?

Fat coals

Solid fuels

Gaseous fuels

Liquid fuels

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