Fuels and Combustion Quiz 1

1 / 50

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

None of these

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

2 / 50

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

Fuel

Neither A. nor B.

Air

Both A. & B.

3 / 50

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

Fixed carbon

Ash

Oxygen

Volatile matter

4 / 50

A coal that softens and fuses on heating is__________?

Caking

Carbonised

Classified

Non-caking

5 / 50

A coal having high volatile matter content will _________?

Have a very high calorific value

None of these

Burn with a small non-smoky flame

Give less yield of tar and gas on carbonisation

6 / 50

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

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

Supply of excess fuel

Supply of excess air

None of these

7 / 50

A coal with high ash content is undesirable, as_________?

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

All A., B. and C.

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

8 / 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

9 / 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

10 / 50

A coal having higher volatile matter content, has lower__________?

Coke oven gas yield on carbonisation

Chance of catching fire during storage in open space

Ignition temperature

Smoking tendency on burning

11 / 50

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

Combustion

Nuclear fission

All A., B. & C.

Nuclear fusion

12 / 50

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

Ash fusion temperature

Caking index

Calorific value

Ignition temperature

13 / 50

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

2.5

10.5

14.5

7.5

14 / 50

A fuel with high heat release rate will__________?

Have high adiabatic flame temperature

Require smaller combustion chamber

Have high calorific value

None of these

15 / 50

?Fat? coal means a coal having _____?

Low calorific value

Low ash content

Non smoking tendency

High volatile matter

16 / 50

__________ is used as jet engine fuel ?

LPG

Kerosene

Petrol

Diesel

17 / 50

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

> 120

> 280

< 120

300-600

18 / 50

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

Hydrogen

Methane

Acetylene

Carbon monoxide

19 / 50

A good quality coal should have _____?

High sulphur

None of these

Low fusion point of ash

High ash content

20 / 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

None of these

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

21 / 50

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

Hydrocarbons

Hydrogen

Oxygen

Carbon monoxide

22 / 50

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

Fixed carbon

Hydrogen

Total carbon

Nitrogen

23 / 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

3 to 4

20 to 40

1 to 2

24 / 50

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

Volatile matter content

Caking capacity

Inherent moisture content

Fusion point of its ash

25 / 50

?Wobbe index? is a characteristic of___________?

Gaseous fuels

Solid fuels

Fat coals

Liquid fuels

26 / 50

A coal having high amount of volatile matter______?

Ignites easily and burns with long smoky flame

Would require smaller combustion chamber

Produces very little of tar and gas on carbonisation

All A., B. and C.

27 / 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

28 / 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

High sulphur content in the fuel

Lack of thorough mixing of fuel with air

Presence of large quantity of hydrogen in the fuel

29 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low octane number

Low flash point

High cost & availability

Low calorific value

30 / 50

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

Boghead

Splint

Non-banded

Bright

31 / 50

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

100

32 / 50

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

33 / 50

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

Gives smokeless burning

Burns completely

None of these

Shows little or no fusing action

34 / 50

Advantages of fluidised bed combustion are ______?

Lower furnace operating temperature

Reduced NOx formation in flue gas

High heat transfer rate

All A., B. & C.

35 / 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

36 / 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

37 / 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

None of these

Requires smaller combustion space and less secondary air

Is more difficult to ignite and produces a shorter flame

38 / 50

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

Carburetted water gas

Gobar gas

Coke oven gas

LPG

39 / 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

Lower carbon dioxide content

None of these

40 / 50

A coal with high ash content_____?

Is not subjected to washing

Has higher calorific value

Has low quantity of mineral matter

Is harder and stronger

41 / 50

A good coking coal should have high _______ content?

Sulphur & phosphorus

None of these

Moisture

Ash

42 / 50

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

43 / 50

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

Calorific value

Caking index

Ultimate analysis

Proximate analysis

44 / 50

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

Variation in the pitch of the fan blades

Speed of the fan

All A., B. and C.

Damper

45 / 50

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

Fischer-Tropsch

Bergius

None of these

Lurgi

46 / 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

47 / 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 : 7.42, CO : 1.86, O2 : 4.64, N2:86.02

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

48 / 50

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

Pulverised

Caking

High ash

Non-caking

49 / 50

Anthracite coal ______?

Is essentially a coking coal

Contains more volatile matter than bituminous coal

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

Ignites more easily than bituminous coal

50 / 50

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

Porosity

Reactivity

Bulk density

Hardness & strength

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