Fuels and Combustion Quiz 1

1 / 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

2 / 50

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

None of these

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

Supply of excess air

Supply of excess fuel

3 / 50

A good coking coal should have high _______ content?

Ash

Moisture

None of these

Sulphur & phosphorus

4 / 50

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

Both A. and B.

Neither A. nor B.

No possibility of obtaining complete combustion at high temperature

Always loss of heat from the flame

5 / 50

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

Volatile matter content

Fusion point of its ash

Inherent moisture content

Caking capacity

6 / 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

7 / 50

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

8 / 50

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

Gobar gas

LPG

Carburetted water gas

Coke oven gas

9 / 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

10 / 50

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

Splint

Non-banded

Bright

Boghead

11 / 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

12 / 50

A fuel with high heat release rate will__________?

None of these

Have high adiabatic flame temperature

Require smaller combustion chamber

Have high calorific value

13 / 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

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

All A., B. and C.

14 / 50

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

100

15 / 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

16 / 50

A good quality coal should have _____?

None of these

High ash content

Low fusion point of ash

High sulphur

17 / 50

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

Acetylene

Methane

Hydrogen

Carbon monoxide

18 / 50

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

Hydrocarbons

Oxygen

Hydrogen

Carbon monoxide

19 / 50

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

Air

Neither A. nor B.

Fuel

Both A. & B.

20 / 50

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

None of these

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

21 / 50

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

None of these

Burns completely

Gives smokeless burning

Shows little or no fusing action

22 / 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

23 / 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

24 / 50

A coal containing high amount of volatile matter will have___________?

Low adiabatic flame temperature

Very little ash content

High fusion point of its ash

Low ignition temperature

25 / 50

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

10.5

14.5

7.5

2.5

26 / 50

A coal that softens and fuses on heating is__________?

Carbonised

Classified

Caking

Non-caking

27 / 50

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

Nuclear fission

Combustion

Nuclear fusion

All A., B. & C.

28 / 50

Anthracite coal ______?

Is essentially a coking coal

Ignites more easily than bituminous coal

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

Contains more volatile matter than bituminous coal

29 / 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.

30 / 50

?Fat? coal means a coal having _____?

Non smoking tendency

Low calorific value

High volatile matter

Low ash content

31 / 50

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

Volatile matter

Ash

Oxygen

Fixed carbon

32 / 50

Advantages of fluidised bed combustion are ______?

Lower furnace operating temperature

All A., B. & C.

Reduced NOx formation in flue gas

High heat transfer rate

33 / 50

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

Lurgi

None of these

Fischer-Tropsch

Bergius

34 / 50

A good metallurgical coke_____?

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

Should be brittle

Should have high porosity

Should have low fusion point of its ash

35 / 50

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

Non-caking

Pulverised

Caking

High ash

36 / 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

37 / 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

None of these

Higher methane content and thus higher calorific value

Higher carbon monoxide content

38 / 50

__________ is used as jet engine fuel ?

Kerosene

LPG

Diesel

Petrol

39 / 50

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

Reactivity

Hardness & strength

Porosity

Bulk density

40 / 50

A coal having higher volatile matter content, has lower__________?

Coke oven gas yield on carbonisation

Smoking tendency on burning

Chance of catching fire during storage in open space

Ignition temperature

41 / 50

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

Ignition temperature

Calorific value

Ash fusion temperature

Caking index

42 / 50

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

300-600

> 280

< 120

> 120

43 / 50

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

Total carbon

Fixed carbon

Hydrogen

Nitrogen

44 / 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

45 / 50

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

46 / 50

A coal having high volatile matter content will _________?

Give less yield of tar and gas on carbonisation

Burn with a small non-smoky flame

None of these

Have a very high calorific value

47 / 50

?Wobbe index? is a characteristic of___________?

Gaseous fuels

Liquid fuels

Solid fuels

Fat coals

48 / 50

______ prohibits the use of alcohols directly in petrol engines ?

High cost & availability

Low flash point

Low octane number

Low calorific value

49 / 50

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

Proximate analysis

Ultimate analysis

Calorific value

Caking index

50 / 50

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

Speed of the fan

Damper

Variation in the pitch of the fan blades

All A., B. and C.

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