Fuels and Combustion Quiz 1

1 / 50

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

Bright

Boghead

Splint

Non-banded

2 / 50

A coal that softens and fuses on heating is__________?

Carbonised

Classified

Caking

Non-caking

3 / 50

Advantages of fluidised bed combustion are ______?

Reduced NOx formation in flue gas

All A., B. & C.

High heat transfer rate

Lower furnace operating temperature

4 / 50

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

Carbon monoxide

Hydrocarbons

Oxygen

Hydrogen

5 / 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

6 / 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

Higher carbon monoxide content

None of these

Lower carbon dioxide content

7 / 50

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

Caking index

Calorific value

Ultimate analysis

Proximate analysis

8 / 50

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

Fixed carbon

Volatile matter

Oxygen

Ash

9 / 50

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

< 120

> 280

300-600

> 120

10 / 50

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

None of these

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

Supply of excess air

Supply of excess fuel

11 / 50

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

Speed of the fan

All A., B. and C.

Variation in the pitch of the fan blades

Damper

12 / 50

A coal having high volatile matter content will _________?

None of these

Give less yield of tar and gas on carbonisation

Have a very high calorific value

Burn with a small non-smoky flame

13 / 50

?Wobbe index? is a characteristic of___________?

Fat coals

Solid fuels

Gaseous fuels

Liquid fuels

14 / 50

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

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

None of these

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

Fixed carbon and heating value around 132 BTU/1b

15 / 50

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

16 / 50

__________ is used as jet engine fuel ?

Kerosene

Petrol

LPG

Diesel

17 / 50

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

High ash

Pulverised

Non-caking

Caking

18 / 50

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

10.5

2.5

14.5

7.5

19 / 50

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

20 / 50

A good coking coal should have high _______ content?

None of these

Sulphur & phosphorus

Moisture

Ash

21 / 50

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

Gives smokeless burning

None of these

Shows little or no fusing action

Burns completely

22 / 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

Requires smaller combustion space and less secondary air

Is less liable to spontaneous combustion on storage

23 / 50

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

Both A. & B.

Air

Neither A. nor B.

Fuel

24 / 50

A coal having high amount of volatile matter______?

All A., B. and C.

Would require smaller combustion chamber

Produces very little of tar and gas on carbonisation

Ignites easily and burns with long smoky flame

25 / 50

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

Ignition temperature

Ash fusion temperature

Caking index

Calorific value

26 / 50

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

Acetylene

Carbon monoxide

Hydrogen

Methane

27 / 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

No excess air has been used for combustion

21% excess oxygen has been used for combustion

21% excess air has been used for combustion

28 / 50

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

100

29 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low octane number

High cost & availability

Low flash point

Low calorific value

30 / 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 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60

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

31 / 50

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

Fusion point of its ash

Volatile matter content

Caking capacity

Inherent moisture content

32 / 50

A good metallurgical coke_____?

Should have low fusion point of its ash

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

Should have high porosity

Should be brittle

33 / 50

A coal with high ash content_____?

Has low quantity of mineral matter

Is not subjected to washing

Is harder and stronger

Has higher calorific value

34 / 50

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

Always loss of heat from the flame

No possibility of obtaining complete combustion at high temperature

Neither A. nor B.

Both A. and B.

35 / 50

?Fat? coal means a coal having _____?

Non smoking tendency

Low calorific value

Low ash content

High volatile matter

36 / 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

All A., B. and C.

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

37 / 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

38 / 50

Anthracite can be used for_____?

All A., B. and C.

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

39 / 50

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

LPG

Gobar gas

Carburetted water gas

Coke oven gas

40 / 50

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

Bulk density

Hardness & strength

Porosity

Reactivity

41 / 50

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

Nuclear fission

All A., B. & C.

Combustion

Nuclear fusion

42 / 50

A coal containing high amount of volatile matter will have___________?

Low adiabatic flame temperature

High fusion point of its ash

Low ignition temperature

Very little ash content

43 / 50

A fuel with high heat release rate will__________?

Have high calorific value

Have high adiabatic flame temperature

None of these

Require smaller combustion chamber

44 / 50

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

Total carbon

Nitrogen

Hydrogen

Fixed carbon

45 / 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

46 / 50

A good quality coal should have _____?

High sulphur

Low fusion point of ash

High ash content

None of these

47 / 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

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

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

48 / 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

3 to 4

1 to 2

5 to 15

49 / 50

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

None of these

Fischer-Tropsch

Lurgi

Bergius

50 / 50

A coal having higher volatile matter content, has lower__________?

Ignition temperature

Coke oven gas yield on carbonisation

Chance of catching fire during storage in open space

Smoking tendency on burning

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