Fuels and Combustion Quiz 1

1 / 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

2 / 50

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

Carbon monoxide

Hydrogen

Hydrocarbons

Oxygen

3 / 50

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

300-600

> 120

> 280

< 120

4 / 50

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

Lurgi

Bergius

Fischer-Tropsch

None of these

5 / 50

A good metallurgical coke_____?

Should be brittle

Should have low fusion point of its ash

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

Should have high porosity

6 / 50

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

Shows little or no fusing action

Gives smokeless burning

Burns completely

None of these

7 / 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 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

None of these

8 / 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

9 / 50

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

Caking

Pulverised

High ash

Non-caking

10 / 50

A coal having higher volatile matter content, has lower__________?

Coke oven gas yield on carbonisation

Ignition temperature

Chance of catching fire during storage in open space

Smoking tendency on burning

11 / 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

12 / 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

All A., B. and C.

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

13 / 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

None of these

Higher carbon monoxide content

14 / 50

A good quality coal should have _____?

High ash content

Low fusion point of ash

High sulphur

None of these

15 / 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

16 / 50

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

Fixed carbon and heating value around 132 BTU/1b

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

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

None of these

17 / 50

A coal containing high amount of volatile matter will have___________?

Very little ash content

Low adiabatic flame temperature

High fusion point of its ash

Low ignition temperature

18 / 50

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

Calorific value

Ignition temperature

Caking index

Ash fusion temperature

19 / 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

3 to 4

20 to 40

20 / 50

A coal that softens and fuses on heating is__________?

Carbonised

Classified

Non-caking

Caking

21 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low octane number

Low calorific value

High cost & availability

Low flash point

22 / 50

A coal having high amount of volatile matter______?

Would require smaller combustion chamber

Ignites easily and burns with long smoky flame

All A., B. and C.

Produces very little of tar and gas on carbonisation

23 / 50

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

7.5

10.5

2.5

14.5

24 / 50

A good coking coal should have high _______ content?

Ash

Sulphur & phosphorus

None of these

Moisture

25 / 50

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

100

26 / 50

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

Acetylene

Hydrogen

Carbon monoxide

Methane

27 / 50

?Fat? coal means a coal having _____?

Low ash content

Low calorific value

Non smoking tendency

High volatile matter

28 / 50

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

29 / 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.

30 / 50

A coal having high volatile matter content will _________?

Burn with a small non-smoky flame

None of these

Give less yield of tar and gas on carbonisation

Have a very high calorific value

31 / 50

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

Fuel

Air

Both A. & B.

Neither A. nor B.

32 / 50

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

Hardness & strength

Porosity

Bulk density

Reactivity

33 / 50

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

Damper

Speed of the fan

Variation in the pitch of the fan blades

All A., B. and C.

34 / 50

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

Hydrogen

Nitrogen

Fixed carbon

Total carbon

35 / 50

__________ is used as jet engine fuel ?

Petrol

Kerosene

Diesel

LPG

36 / 50

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

21% excess oxygen has been used for combustion

No excess air has been used for combustion

Complete combustion of fuel has taken place

21% excess air has been used for combustion

37 / 50

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

None of these

Supply of excess air

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

Supply of excess fuel

38 / 50

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

Nuclear fission

All A., B. & C.

Combustion

Nuclear fusion

39 / 50

?Wobbe index? is a characteristic of___________?

Solid fuels

Fat coals

Gaseous fuels

Liquid fuels

40 / 50

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

Proximate analysis

Calorific value

Ultimate analysis

Caking index

41 / 50

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

42 / 50

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

Non-banded

Boghead

Splint

Bright

43 / 50

Anthracite coal ______?

Is essentially a coking coal

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

Contains more volatile matter than bituminous coal

Ignites more easily than bituminous coal

44 / 50

Advantages of fluidised bed combustion are ______?

All A., B. & C.

Reduced NOx formation in flue gas

High heat transfer rate

Lower furnace operating temperature

45 / 50

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

Volatile matter

Oxygen

Fixed carbon

Ash

46 / 50

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

Fusion point of its ash

Caking capacity

Volatile matter content

Inherent moisture content

47 / 50

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

Coke oven gas

LPG

Gobar gas

Carburetted water gas

48 / 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.

49 / 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 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60

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

50 / 50

A fuel with high heat release rate will__________?

Require smaller combustion chamber

Have high calorific value

None of these

Have high adiabatic flame temperature

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