Fuels and Combustion Quiz 1

1 / 50

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

300-600

> 120

< 120

> 280

2 / 50

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

Fixed carbon and heating value around 132 BTU/1b

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

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

None of these

3 / 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 air has been used for combustion

21% excess oxygen has been used for combustion

4 / 50

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

5 / 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

Presence of large quantity of hydrogen in the fuel

Lack of thorough mixing of fuel with air

Low calorific value of the fuel

6 / 50

Anthracite coal ______?

Is essentially a coking 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

7 / 50

A good metallurgical coke_____?

Should have low fusion point of its ash

Should have high porosity

Should be brittle

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

8 / 50

A coal having high volatile matter content will _________?

Burn with a small non-smoky flame

Give less yield of tar and gas on carbonisation

Have a very high calorific value

None of these

9 / 50

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

10 / 50

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

No possibility of obtaining complete combustion at high temperature

Both A. and B.

Always loss of heat from the flame

Neither A. nor B.

11 / 50

A coal having higher volatile matter content, has lower__________?

Chance of catching fire during storage in open space

Smoking tendency on burning

Coke oven gas yield on carbonisation

Ignition temperature

12 / 50

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

Burns completely

Gives smokeless burning

Shows little or no fusing action

None of these

13 / 50

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

Carbon monoxide

Oxygen

Hydrocarbons

Hydrogen

14 / 50

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

100

15 / 50

A good coking coal should have high _______ content?

None of these

Moisture

Sulphur & phosphorus

Ash

16 / 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

5 to 15

1 to 2

17 / 50

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

All A., B. and C.

Variation in the pitch of the fan blades

Damper

Speed of the fan

18 / 50

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

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

None of these

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

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

19 / 50

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

Volatile matter

Ash

Oxygen

Fixed carbon

20 / 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 carbon monoxide content

None of these

Lower carbon dioxide content

Higher methane content and thus higher calorific value

21 / 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

22 / 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 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

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

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

23 / 50

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

Ultimate analysis

Caking index

Calorific value

Proximate analysis

24 / 50

?Fat? coal means a coal having _____?

Low calorific value

Non smoking tendency

High volatile matter

Low ash content

25 / 50

A coal with high ash content_____?

Has low quantity of mineral matter

Is not subjected to washing

Has higher calorific value

Is harder and stronger

26 / 50

A coal with high ash content is undesirable, as_________?

All A., B. and C.

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

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

27 / 50

__________ is used as jet engine fuel ?

Kerosene

Petrol

LPG

Diesel

28 / 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

29 / 50

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

Fusion point of its ash

Volatile matter content

Caking capacity

Inherent moisture content

30 / 50

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

Hardness & strength

Reactivity

Porosity

Bulk density

31 / 50

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

Nuclear fusion

All A., B. & C.

Nuclear fission

Combustion

32 / 50

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

Hydrogen

Carbon monoxide

Acetylene

Methane

33 / 50

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

Bright

Splint

Boghead

Non-banded

34 / 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 __________?

Requires smaller combustion space and less secondary air

Is less liable to spontaneous combustion on storage

None of these

Is more difficult to ignite and produces a shorter flame

35 / 50

A coal having high amount of volatile matter______?

Would require smaller combustion chamber

Produces very little of tar and gas on carbonisation

Ignites easily and burns with long smoky flame

All A., B. and C.

36 / 50

A fuel with high heat release rate will__________?

None of these

Have high calorific value

Require smaller combustion chamber

Have high adiabatic flame temperature

37 / 50

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

Air

Neither A. nor B.

Both A. & B.

Fuel

38 / 50

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

Coke oven gas

Carburetted water gas

Gobar gas

LPG

39 / 50

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

None of these

Supply of excess fuel

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

Supply of excess air

40 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low calorific value

Low flash point

High cost & availability

Low octane number

41 / 50

?Wobbe index? is a characteristic of___________?

Fat coals

Solid fuels

Gaseous fuels

Liquid fuels

42 / 50

A coal that softens and fuses on heating is__________?

Classified

Caking

Non-caking

Carbonised

43 / 50

A good quality coal should have _____?

High sulphur

High ash content

Low fusion point of ash

None of these

44 / 50

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

Total carbon

Hydrogen

Fixed carbon

Nitrogen

45 / 50

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

Fischer-Tropsch

None of these

Bergius

Lurgi

46 / 50

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

High ash

Caking

Non-caking

Pulverised

47 / 50

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

Ash fusion temperature

Caking index

Ignition temperature

Calorific value

48 / 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

49 / 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.

50 / 50

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

2.5

7.5

14.5

10.5

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