Fuels and Combustion Quiz 1

1 / 50

A good metallurgical coke_____?

Should be brittle

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

Should have low fusion point of its ash

Should have high porosity

2 / 50

A good coking coal should have high _______ content?

Ash

None of these

Moisture

Sulphur & phosphorus

3 / 50

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

Carbon monoxide

Acetylene

Hydrogen

Methane

4 / 50

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

Nitrogen

Total carbon

Hydrogen

Fixed carbon

5 / 50

?Fat? coal means a coal having _____?

Non smoking tendency

Low ash content

Low calorific value

High volatile matter

6 / 50

A coal containing high amount of volatile matter will have___________?

Very little ash content

High fusion point of its ash

Low ignition temperature

Low adiabatic flame temperature

7 / 50

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

Nuclear fission

All A., B. & C.

Combustion

Nuclear fusion

8 / 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 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

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

9 / 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

1 to 2

5 to 15

3 to 4

10 / 50

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

Both A. & B.

Neither A. nor B.

Fuel

Air

11 / 50

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

Supply of excess fuel

Supply of excess air

None of these

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

12 / 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

None of these

Higher methane content and thus higher calorific value

13 / 50

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

Caking

Non-caking

High ash

Pulverised

14 / 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

No possibility of obtaining complete combustion at high temperature

Neither A. nor B.

15 / 50

Anthracite coal ______?

Ignites more easily than bituminous coal

Contains more volatile matter than bituminous coal

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

Is essentially a coking coal

16 / 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

17 / 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

18 / 50

?Wobbe index? is a characteristic of___________?

Gaseous fuels

Fat coals

Liquid fuels

Solid fuels

19 / 50

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

All A., B. and C.

Damper

Speed of the fan

Variation in the pitch of the fan blades

20 / 50

A coal with high ash content_____?

Has low quantity of mineral matter

Has higher calorific value

Is not subjected to washing

Is harder and stronger

21 / 50

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

Calorific value

Ignition temperature

Ash fusion temperature

Caking index

22 / 50

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

10.5

14.5

2.5

7.5

23 / 50

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

Inherent moisture content

Caking capacity

Volatile matter content

Fusion point of its ash

24 / 50

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

Boghead

Non-banded

Splint

Bright

25 / 50

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

> 280

300-600

> 120

< 120

26 / 50

A good quality coal should have _____?

High sulphur

None of these

High ash content

Low fusion point of ash

27 / 50

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

Oxygen

Fixed carbon

Ash

Volatile matter

28 / 50

A fuel with high heat release rate will__________?

Require smaller combustion chamber

None of these

Have high adiabatic flame temperature

Have high calorific value

29 / 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

21% excess oxygen has been used for combustion

Complete combustion of fuel has taken place

No excess air has been used for combustion

30 / 50

Anthracite can be used for_____?

Recarbonising steel

All A., B. and C.

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

31 / 50

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

Gobar gas

LPG

Coke oven gas

Carburetted water gas

32 / 50

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

None of these

Lurgi

Fischer-Tropsch

Bergius

33 / 50

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

34 / 50

Advantages of fluidised bed combustion are ______?

Reduced NOx formation in flue gas

High heat transfer rate

Lower furnace operating temperature

All A., B. & C.

35 / 50

A coal having high volatile matter content will _________?

Burn with a small non-smoky flame

Have a very high calorific value

Give less yield of tar and gas on carbonisation

None of these

36 / 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

37 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low flash point

Low octane number

Low calorific value

High cost & availability

38 / 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__________?

Lack of thorough mixing of fuel with air

High sulphur content in the fuel

Low calorific value of the fuel

Presence of large quantity of hydrogen in the fuel

39 / 50

__________ is used as jet engine fuel ?

LPG

Diesel

Kerosene

Petrol

40 / 50

A coal having higher volatile matter content, has lower__________?

Smoking tendency on burning

Coke oven gas yield on carbonisation

Chance of catching fire during storage in open space

Ignition temperature

41 / 50

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

100

42 / 50

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

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

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

None of these

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

43 / 50

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

Porosity

Reactivity

Hardness & strength

Bulk density

44 / 50

A coal that softens and fuses on heating is__________?

Non-caking

Classified

Carbonised

Caking

45 / 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

Less

Same

46 / 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

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

All A., B. and C.

47 / 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

None of these

Requires smaller combustion space and less secondary air

48 / 50

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

Ultimate analysis

Calorific value

Caking index

Proximate analysis

49 / 50

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

Hydrocarbons

Carbon monoxide

Oxygen

Hydrogen

50 / 50

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

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