Fuels and Combustion Quiz 1

1 / 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

2 / 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

3 / 50

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

Inherent moisture content

Volatile matter content

Caking capacity

Fusion point of its ash

4 / 50

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

14.5

2.5

7.5

10.5

5 / 50

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

Proximate analysis

Calorific value

Ultimate analysis

Caking index

6 / 50

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

Fixed carbon

Hydrogen

Nitrogen

Total carbon

7 / 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 _______?

None of these

Higher carbon monoxide content

Higher methane content and thus higher calorific value

Lower carbon dioxide content

8 / 50

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

Porosity

Bulk density

Reactivity

Hardness & strength

9 / 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

Low calorific value of the fuel

Lack of thorough mixing of fuel with air

Presence of large quantity of hydrogen in the fuel

10 / 50

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

Fixed carbon

Volatile matter

Oxygen

Ash

11 / 50

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

High ash

Non-caking

Caking

Pulverised

12 / 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 : 6.39, 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

CO2 : 7.42, CO : 1.86, O2 : 4.64, N2:86.02

13 / 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

14 / 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

15 / 50

?Fat? coal means a coal having _____?

Non smoking tendency

Low ash content

Low calorific value

High volatile matter

16 / 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

None of these

Requires smaller combustion space and less secondary air

Is less liable to spontaneous combustion on storage

17 / 50

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

Splint

Non-banded

Bright

Boghead

18 / 50

A good coking coal should have high _______ content?

Sulphur & phosphorus

Ash

Moisture

None of these

19 / 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

20 / 50

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

None of these

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

Fixed carbon and heating value around 132 BTU/1b

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

21 / 50

__________ is used as jet engine fuel ?

Petrol

Kerosene

LPG

Diesel

22 / 50

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

None of these

Lurgi

Fischer-Tropsch

Bergius

23 / 50

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

Fuel

Neither A. nor B.

Both A. & B.

Air

24 / 50

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

No possibility of obtaining complete combustion at high temperature

Neither A. nor B.

Both A. and B.

Always loss of heat from the flame

25 / 50

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

Gobar gas

LPG

Carburetted water gas

Coke oven gas

26 / 50

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

100

27 / 50

A coal containing high amount of volatile matter will have___________?

High fusion point of its ash

Very little ash content

Low adiabatic flame temperature

Low ignition temperature

28 / 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

Complete combustion of fuel has taken place

21% excess air has been used for combustion

No excess air has been used for combustion

29 / 50

A coal with high ash content is undesirable, as_________?

All A., B. and C.

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

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

30 / 50

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

Ash fusion temperature

Calorific value

Ignition temperature

Caking index

31 / 50

A fuel with high heat release rate will__________?

None of these

Have high calorific value

Have high adiabatic flame temperature

Require smaller combustion chamber

32 / 50

A coal having high amount of volatile matter______?

Produces very little of tar and gas on carbonisation

Would require smaller combustion chamber

Ignites easily and burns with long smoky flame

All A., B. and C.

33 / 50

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

Methane

Hydrogen

Acetylene

Carbon monoxide

34 / 50

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

35 / 50

A coal having high volatile matter content will _________?

Have a very high calorific value

Burn with a small non-smoky flame

Give less yield of tar and gas on carbonisation

None of these

36 / 50

A good quality coal should have _____?

High sulphur

High ash content

None of these

Low fusion point of ash

37 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low calorific value

Low flash point

High cost & availability

Low octane number

38 / 50

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

39 / 50

Anthracite coal ______?

Contains more volatile matter than bituminous coal

Is essentially a coking coal

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

Ignites more easily than bituminous coal

40 / 50

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

None of these

Shows little or no fusing action

Burns completely

Gives smokeless burning

41 / 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

42 / 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

43 / 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

3 to 4

5 to 15

44 / 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.

45 / 50

?Wobbe index? is a characteristic of___________?

Fat coals

Solid fuels

Gaseous fuels

Liquid fuels

46 / 50

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

> 280

< 120

300-600

> 120

47 / 50

A coal that softens and fuses on heating is__________?

Non-caking

Caking

Carbonised

Classified

48 / 50

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

Carbon monoxide

Oxygen

Hydrogen

Hydrocarbons

49 / 50

Advantages of fluidised bed combustion are ______?

All A., B. & C.

Lower furnace operating temperature

Reduced NOx formation in flue gas

High heat transfer rate

50 / 50

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

Nuclear fission

All A., B. & C.

Nuclear fusion

Combustion

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