Fuels and Combustion Quiz 6

1 / 50

Pick out the correct statement ?

The less the oxygen content, better is the coal, as it reduces the calorific value

All A., B. and C.

Oxygen content decreases from lignite to bituminous coal as the coalification increases

With increase in oxygen content, moisture holding capacity of coal increases and the caking power decreases

2 / 50

Percentage of nitrogen in blast furnace gas may be around___________?

3 / 50

Preheating of _______ the flame temperature?

Either the fuel or the air or both, increases

Combustion air decreases

The gaseous fuel before combustion decreases

Either the fuel or the air does not affect

4 / 50

Pitch creosote mixture (PCM) as compared to furnace oil is a better fuel, because its _____?

All A., B. and C.

Emissivity factor is higher

Flue gas has lower dew point thereby facilitating more waste heat recovery

Sulphur content is lower

5 / 50

Pick out the wrong statement ?

Specific heat of coal decreases with increases in the volatile matter and decrease in the C/H ratio of coal

Angle of repose of coal increases with its increasing size

Specific gravity of coal increases with its increasing maturity

Refractive index and reflectance of coal increases with the increasing rank of coal

6 / 50

Prime coking coal is always blended with medium or non- coking coal before carbonisation___________?

Neither A. nor B.

To check against its excessive swelling during heating, which may exert high pressure and damage coke oven walls

Both A. and B.

Because, it alone produces unreactive coke

7 / 50

Oxygen required for theoretically complete combustion of 1 Nm3 methane is _______ Nm3?

8 / 50

Preheating of coal charge for the coke ovens reduces the ___________?

Fuel consumption in coking

Time of carbonisation

Yield of gas and tar

All A., B. and C.

9 / 50

Octane number of 2, 2, 4 ? trimethyl pentane is ___________?

In between 0 and 100

100

More than 100

10 / 50

Naphthalene recovered from coke oven gas is used_____?

For making electrodes

As moisture proof coating on fibres

As moth balls (insecticides)

As a fuel in furnaces

11 / 50

Percentage of carbon monoxide in blast furnace gas may be around ______ ?

12 / 50

Out of the following fuels, the difference between gross and net calorific value will be minimum in case of_____?

Water gas

Coke oven gas

Blast furnace gas

Natural gas

13 / 50

Producer gas containing least amount of tar is produced by the__________?

High pressure gasification of coal (e.g. in Lurgi gasifier)

Partial combustion of coal

Partial combustion of large size (< 50 mm) coke

Atmospheric pressure gasification of coal (e.g., in Kopper-Totzek gasifier)

14 / 50

Nitrogen in coal__________?

Is present upto 1-2%

Comes from protein in parent vegetable matter

Is recovered as ammonia during its carbonisation

All A., B. and C.

15 / 50

Orsat apparatus___________?

Gives flue gas analysis on dry basis

All A., B. & C.

Determines N2 in flue gas indirectly

Can?t determine CO in flue gas, if it is < 0.2%

16 / 50

Out of the following fuels, the difference between the net and gross calorific value is maximum in case of__________?

Pitch

Bituminous coal

Fuel oil

Blast furnace gas

17 / 50

Percentage of hydrogen in coke oven gas may be around _____?

18 / 50

Presence of phosphorous in metallurgical coal___________?

Badly affects the quality of steel

Reduces its calorific value

Increases its caking power

Is not undesirable

19 / 50

Pick out the wrong statement ?

High concentration of oxygen in flue gas means high stack loss

Gaseous fuels require the least % excess air for complete combustion

The ratio of fixed carbon to volatile matter percentage in coal is called its ?fuel ratio?

Calorific value of natural gas is more than that of LPG

20 / 50

Producer gas comprises mainly of _________?

CO & H2

CO2 & N2

CO2 & H2

CO & N2

21 / 50

Pick out the wrong statement ?

Percentage of ash in coke produced from medium coking coal is more than that in coal

The calorific value (kcal/Nm3) of coke oven gas reduces on removal of hydrogen from it by cryogenic method

Ash is normally removed as ?fly-ash? in Kopper-Totzek process of coal gasification

Coal based fertiliser plants in India at Talcher (Orissa) and Ramagundam (A.P) employ Kopper-Totzek process of coal gasification

22 / 50

Of the total tar present in raw coke oven gas, the tar recovered in primary cooler is about ________ percent?

23 / 50

Pick out the wrong statement ?

Gross and net calorific value of a fuel is the same, if it does not contain hydrogen or hydrocarbons

Carburetted water gas is also called blue gas

Coals are divided in four species according to their carbon content in Seylor?s classification

Carbonisation time in a by-product coke oven is about 16 hours

24 / 50

Pick out the wrong statement ?

None of these

Low grade coal can be used, but generally high volatile matter coals are more suitable for making pulverised fuel

Pulverised fuel can be completely burnt with less percentage of excess air compared to lump coal

Regulation of furnace temperature and atmosphere (oxidising or reducing) is easily possible with pulverised fuel firing

25 / 50

Presence of force moisture in coal is most disadvantageous during its ___________?

Transportation and handling

Pulverisation

Washing

Storage

26 / 50

Orsat apparatus is meant for _____?

None of these

Gravimetric analysis of flue gas

Finding out combustion efficiency

Direct determination of nitrogen in flue gas by absorbing it in ammoniacal cuprous chloride

27 / 50

Power alcohol as compared to straight run gasoline has lower _________?

Specific gravity

Octane number

Calorific value

Viscosity

28 / 50

Naphthalene is used for making__________?

Insecticides (e.g. moth balls)

Drug intermediates e.g. ?-naphthol

Unsaturated polyesters

All A., B. and C.

29 / 50

Percentage of methane in coke oven gas may be around _______?

30 / 50

Preheating of combustion air is done to _____?

Increase the adiabatic flame temperature

Increase the calorific value of the fuel

Reduce its requirement for effecting the complete combustion

Complete the combustion of fuel

31 / 50

Preheating of a gaseous fuel results in increased______?

Flame temperature

Quantity of flue gas

Flame length

Ignition temperature

32 / 50

Pick out the wrong statement ?

LPG is also used as fuel for automobiles & small furnaces and for cutting & welding of metals

Maximum yield of naphthalene is obtained on distillation of crude oil

The minimum temperature, at which a petroleum oil vapor catches fire and continues to burn, is called its flash point

Each ton of petroleum oil on distillation produces about 30-50 Nm3 of gas

33 / 50

Pensky-Marten apparatus is used for those oils, whose flash points are ______ ?F?

< 90

90-110

< 120

> 120

34 / 50

Presence of free moisture in coal during its high temperature carbonisation _______?

None of these

Protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls

Reduces the coking time

Increases the loss of fine coal dust from the ovens when charging

35 / 50

Pick out the wrong statement ?

Burning the fuel with theoretically required amount of pure oxygen results in attainment of maximum adiabatic flame temperature

Adiabatic flame temperatures of actual combustions are always less than the maximum values

Burning the fuel with excess pure oxygen results in maximum theoretical flame temperature

Theoretical flame temperature is the temperature attained by the products of combustion, when the fuel is burned without loss or gain of heat

36 / 50

Oxygen percentage (by weight) in atmospheric air is__________?

37 / 50

Presence of nitrogen in combustion air does not reduce the ______?

Flame temperature

Flue gas temperature

Any of the above

Amount of heat liberated

38 / 50

One kg of carbon for theoretically complete combustion requires _______ kg of air?

11.5

0.5

39 / 50

Oxygen content in a flue gas was found to be 4%. It implies that excess air used for combustion was around _______ percent?

40 / 50

Presence of _______ in a dry gaseous fuel does not contribute to its calorific value?

Sulphur

Hydrogen

Carbon

Oxygen

41 / 50

Narrow coke ovens as compared to wider coke ovens__________?

Require less time of carbonisation

All A., B. and C.

Produce smaller coke

Produce stronger coke

42 / 50

Natural draft created by the chimney depends upon _______?

Temperature of the flue gas

Neither A. nor B.

Both A. & B.

Its height

43 / 50

Presence of free moisture in coal is most disadvantageous during__________?

Combustion of fire slacks on the grates

None of these

Its pulverisation (as it requires more power)

Handling (e.g. when emptying wagons)

44 / 50

Out of the following, which is the most important parameter for the blast furnace grade coke ?

Volatile matter content

Moisture content

Ash content

CSR & CRI

45 / 50

Number of macrocomponents present in coal according to Stopes are _____?

Four

Two

Six

Five

46 / 50

Net calorific value is the gross calorific value less the ________ heat of water in the product of combustion when cooled to 15?C ?

None of these

Sensible

Sensible and latent

Latent

47 / 50

Nitrogen present in the flue gas is determined in the Orsat apparatus by absorbing it in_______?

Pyrogallol solution

Ammoniacal cuprous chloride

None of these

KOH

48 / 50

Natural draught produced by a chimney depends upon the _______?

Density of the chimney gases

Height of the chimney

Neither A. nor B.

Both A. and B.

49 / 50

Pick out the wrong statement ?

Cokes of high reactivity are obtained from weakly coking coals

Abrasion index of the coke is a measure of its hardness

Cokes of high reactivity are obtained from strongly coking coals

Reactivity of coke is inversely proportional to its absolute density

50 / 50

Pick the odd man out?

Oil gas

Wood

Pitch creosote mixture

Briquettes

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