Fuels and Combustion Quiz 1

1 / 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 carbon monoxide content

Higher methane content and thus higher calorific value

2 / 50

A coal that softens and fuses on heating is__________?

Classified

Carbonised

Non-caking

Caking

3 / 50

?Wobbe index? is a characteristic of___________?

Fat coals

Gaseous fuels

Solid fuels

Liquid fuels

4 / 50

A good quality coal should have _____?

Low fusion point of ash

High ash content

None of these

High sulphur

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__________?

Presence of large quantity of hydrogen in the fuel

Low calorific value of the fuel

Lack of thorough mixing of fuel with air

High sulphur content in the fuel

6 / 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 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60

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

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

7 / 50

A coal having high volatile matter content will _________?

Give less yield of tar and gas on carbonisation

Have a very high calorific value

Burn with a small non-smoky flame

None of these

8 / 50

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

All A., B. & C.

Combustion

Nuclear fission

Nuclear fusion

9 / 50

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

10 / 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

11 / 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 air

Supply of excess fuel

None of these

12 / 50

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

Fixed carbon

Oxygen

Ash

Volatile matter

13 / 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

14 / 50

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

Hydrogen

Oxygen

Hydrocarbons

Carbon monoxide

15 / 50

______ prohibits the use of alcohols directly in petrol engines ?

Low calorific value

Low octane number

High cost & availability

Low flash point

16 / 50

Advantages of fluidised bed combustion are ______?

Reduced NOx formation in flue gas

Lower furnace operating temperature

High heat transfer rate

All A., B. & C.

17 / 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 less liable to spontaneous combustion on storage

Is more difficult to ignite and produces a shorter flame

None of these

Requires smaller combustion space and less secondary air

18 / 50

A good metallurgical coke_____?

Should have low fusion point of its ash

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

Should be brittle

Should have high porosity

19 / 50

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

Caking

High ash

Non-caking

Pulverised

20 / 50

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

Bergius

Fischer-Tropsch

None of these

Lurgi

21 / 50

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

22 / 50

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

Splint

Bright

Boghead

Non-banded

23 / 50

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

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

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

None of these

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

24 / 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

21% excess air has been used for combustion

21% excess oxygen has been used for combustion

No excess air has been used for combustion

25 / 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

All A., B. and C.

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

26 / 50

__________ is used as jet engine fuel ?

Diesel

Petrol

LPG

Kerosene

27 / 50

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

Air

Neither A. nor B.

Fuel

Both A. & B.

28 / 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

29 / 50

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

Caking index

Ignition temperature

Ash fusion temperature

Calorific value

30 / 50

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

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

None of these

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

Fixed carbon and heating value around 132 BTU/1b

31 / 50

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

Ultimate analysis

Calorific value

Proximate analysis

Caking index

32 / 50

?Fat? coal means a coal having _____?

High volatile matter

Low calorific value

Non smoking tendency

Low ash content

33 / 50

A good coking coal should have high _______ content?

Ash

Moisture

Sulphur & phosphorus

None of these

34 / 50

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

Gobar gas

Coke oven gas

LPG

Carburetted water gas

35 / 50

A coal having high amount of volatile matter______?

All A., B. and C.

Produces very little of tar and gas on carbonisation

Ignites easily and burns with long smoky flame

Would require smaller combustion chamber

36 / 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.

Always loss of heat from the flame

Both A. and B.

37 / 50

A fuel with high heat release rate will__________?

Have high calorific value

None of these

Have high adiabatic flame temperature

Require smaller combustion chamber

38 / 50

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

Nitrogen

Hydrogen

Total carbon

Fixed carbon

39 / 50

Anthracite can be used for_____?

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

Recarbonising steel

40 / 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

41 / 50

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

Volatile matter content

Fusion point of its ash

Caking capacity

Inherent moisture content

42 / 50

A coal containing high amount of volatile matter will have___________?

Low adiabatic flame temperature

High fusion point of its ash

Low ignition temperature

Very little ash content

43 / 50

A coal with high ash content_____?

Has higher calorific value

Is harder and stronger

Is not subjected to washing

Has low quantity of mineral matter

44 / 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?

1 to 2

3 to 4

20 to 40

5 to 15

45 / 50

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

Hardness & strength

Porosity

Reactivity

Bulk density

46 / 50

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

10.5

14.5

2.5

7.5

47 / 50

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

100

48 / 50

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

> 120

300-600

> 280

< 120

49 / 50

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

Speed of the fan

All A., B. and C.

Variation in the pitch of the fan blades

Damper

50 / 50

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

Carbon monoxide

Acetylene

Hydrogen

Methane

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