Fuels and Combustion Quiz 1

1 / 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 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

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

2 / 50

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

None of these

Fischer-Tropsch

Bergius

Lurgi

3 / 50

A good coking coal should have high _______ content?

Sulphur & phosphorus

Ash

None of these

Moisture

4 / 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

5 / 50

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

Nuclear fusion

Combustion

All A., B. & C.

Nuclear fission

6 / 50

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

Fixed carbon

Ash

Oxygen

Volatile matter

7 / 50

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

Ignition temperature

Ash fusion temperature

Calorific value

Caking index

8 / 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

9 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low octane number

Low flash point

High cost & availability

Low calorific value

10 / 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

11 / 50

A good metallurgical coke_____?

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

Should have low fusion point of its ash

Should be brittle

Should have high porosity

12 / 50

__________ is used as jet engine fuel ?

LPG

Petrol

Kerosene

Diesel

13 / 50

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

Air

Both A. & B.

Neither A. nor B.

Fuel

14 / 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

None of these

Supply of excess fuel

Supply of excess air

15 / 50

A coal having high volatile matter content will _________?

Have a very high calorific value

None of these

Give less yield of tar and gas on carbonisation

Burn with a small non-smoky flame

16 / 50

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

300-600

> 280

< 120

> 120

17 / 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

18 / 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

19 / 50

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

Pulverised

Non-caking

High ash

Caking

20 / 50

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

Caking capacity

Volatile matter content

Fusion point of its ash

Inherent moisture content

21 / 50

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

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

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

22 / 50

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

Non-banded

Splint

Bright

Boghead

23 / 50

A coal containing high amount of volatile matter will have___________?

Low ignition temperature

Low adiabatic flame temperature

High fusion point of its ash

Very little ash content

24 / 50

A coal having high amount of volatile matter______?

Would require smaller combustion chamber

All A., B. and C.

Ignites easily and burns with long smoky flame

Produces very little of tar and gas on carbonisation

25 / 50

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

2.5

7.5

10.5

14.5

26 / 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

Is more difficult to ignite and produces a shorter flame

None of these

27 / 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

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

All A., B. and C.

28 / 50

?Wobbe index? is a characteristic of___________?

Fat coals

Liquid fuels

Solid fuels

Gaseous fuels

29 / 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__________?

Less

Data insufficient; can?t be predicted

Same

30 / 50

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

Carburetted water gas

Coke oven gas

Gobar gas

LPG

31 / 50

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

Acetylene

Methane

Hydrogen

Carbon monoxide

32 / 50

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

100

33 / 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__________?

Presence of large quantity of hydrogen in the fuel

Lack of thorough mixing of fuel with air

Low calorific value of the fuel

High sulphur content in the fuel

34 / 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

35 / 50

?Fat? coal means a coal having _____?

High volatile matter

Low calorific value

Low ash content

Non smoking tendency

36 / 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.

37 / 50

Advantages of fluidised bed combustion are ______?

High heat transfer rate

Lower furnace operating temperature

Reduced NOx formation in flue gas

All A., B. & C.

38 / 50

A coal with high ash content_____?

Is not subjected to washing

Has higher calorific value

Is harder and stronger

Has low quantity of mineral matter

39 / 50

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

40 / 50

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

Oxygen

Hydrocarbons

Carbon monoxide

Hydrogen

41 / 50

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

Calorific value

Proximate analysis

Ultimate analysis

Caking index

42 / 50

A coal that softens and fuses on heating is__________?

Carbonised

Caking

Non-caking

Classified

43 / 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 methane content and thus higher calorific value

None of these

Higher carbon monoxide content

44 / 50

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

Nitrogen

Total carbon

Hydrogen

Fixed carbon

45 / 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

Making carbon electrodes

All A., B. and C.

Recarbonising steel

46 / 50

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

Speed of the fan

Variation in the pitch of the fan blades

All A., B. and C.

Damper

47 / 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

Smoking tendency on burning

Ignition temperature

48 / 50

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

Porosity

Hardness & strength

Reactivity

Bulk density

49 / 50

A good quality coal should have _____?

None of these

Low fusion point of ash

High ash content

High sulphur

50 / 50

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

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