Fuels and Combustion Quiz 6

1 / 50

Pick out the wrong statement ?

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

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

Maximum yield of naphthalene is obtained on distillation of crude oil

2 / 50

Natural draft created by the chimney depends upon _______?

Both A. & B.

Neither A. nor B.

Temperature of the flue gas

Its height

3 / 50

Preheating of a gaseous fuel results in increased______?

Flame temperature

Quantity of flue gas

Ignition temperature

Flame length

4 / 50

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

Four

Six

Five

Two

5 / 50

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

Neither A. nor B.

Both A. and B.

Because, it alone produces unreactive coke

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

6 / 50

Pick the odd man out?

Pitch creosote mixture

Wood

Briquettes

Oil gas

7 / 50

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

Ammoniacal cuprous chloride

KOH

None of these

Pyrogallol solution

8 / 50

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

9 / 50

Narrow coke ovens as compared to wider coke ovens__________?

All A., B. and C.

Produce smaller coke

Require less time of carbonisation

Produce stronger coke

10 / 50

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

Ash content

Moisture content

Volatile matter content

CSR & CRI

11 / 50

Pick out the wrong statement ?

Cokes of high reactivity are obtained from weakly coking coals

Reactivity of coke is inversely proportional to its absolute density

Cokes of high reactivity are obtained from strongly coking coals

Abrasion index of the coke is a measure of its hardness

12 / 50

Naphthalene is used for making__________?

Unsaturated polyesters

Drug intermediates e.g. ?-naphthol

Insecticides (e.g. moth balls)

All A., B. and C.

13 / 50

Nitrogen in coal__________?

Comes from protein in parent vegetable matter

Is recovered as ammonia during its carbonisation

Is present upto 1-2%

All A., B. and C.

14 / 50

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

Viscosity

Calorific value

Specific gravity

Octane number

15 / 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

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

Specific gravity of coal increases with its increasing maturity

16 / 50

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

17 / 50

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

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

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

None of these

Reduces the coking time

18 / 50

Oxygen percentage (by weight) in atmospheric air is__________?

19 / 50

Pick out the correct statement ?

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

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

All A., B. and C.

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

20 / 50

Orsat apparatus___________?

All A., B. & C.

Determines N2 in flue gas indirectly

Gives flue gas analysis on dry basis

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

21 / 50

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

Blast furnace gas

Water gas

Natural gas

Coke oven gas

22 / 50

Pick out the wrong statement ?

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

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

None of these

23 / 50

Pick out the wrong statement ?

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

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

24 / 50

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

In between 0 and 100

100

More than 100

25 / 50

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

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

Sulphur content is lower

All A., B. and C.

Emissivity factor is higher

26 / 50

Preheating of combustion air is done to _____?

Complete the combustion of fuel

Reduce its requirement for effecting the complete combustion

Increase the adiabatic flame temperature

Increase the calorific value of the fuel

27 / 50

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

28 / 50

Naphthalene recovered from coke oven gas is used_____?

As moth balls (insecticides)

For making electrodes

As moisture proof coating on fibres

As a fuel in furnaces

29 / 50

Preheating of _______ the flame temperature?

Either the fuel or the air does not affect

Combustion air decreases

Either the fuel or the air or both, increases

The gaseous fuel before combustion decreases

30 / 50

Pick out the wrong statement ?

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

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

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

Carburetted water gas is also called blue gas

31 / 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

Latent

Sensible and latent

32 / 50

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

< 120

< 90

> 120

90-110

33 / 50

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

Sulphur

Carbon

Oxygen

Hydrogen

34 / 50

Percentage of nitrogen in blast furnace gas may be around___________?

35 / 50

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

36 / 50

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

37 / 50

Pick out the wrong statement ?

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

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

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

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

38 / 50

Orsat apparatus is meant for _____?

None of these

Gravimetric analysis of flue gas

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

Finding out combustion efficiency

39 / 50

Presence of free moisture in coal is most disadvantageous during__________?

Its pulverisation (as it requires more power)

Handling (e.g. when emptying wagons)

Combustion of fire slacks on the grates

None of these

40 / 50

Producer gas comprises mainly of _________?

CO2 & H2

CO & H2

CO & N2

CO2 & N2

41 / 50

Pick out the wrong statement ?

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

High concentration of oxygen in flue gas means high stack loss

Calorific value of natural gas is more than that of LPG

Gaseous fuels require the least % excess air for complete combustion

42 / 50

Presence of phosphorous in metallurgical coal___________?

Reduces its calorific value

Is not undesirable

Increases its caking power

Badly affects the quality of steel

43 / 50

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

Amount of heat liberated

Flame temperature

Any of the above

Flue gas temperature

44 / 50

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

11.5

0.5

45 / 50

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

Storage

Transportation and handling

Washing

Pulverisation

46 / 50

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

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

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

Partial combustion of coal

Partial combustion of large size (< 50 mm) coke

47 / 50

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

Bituminous coal

Fuel oil

Pitch

Blast furnace gas

48 / 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.

49 / 50

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

50 / 50

Natural draught produced by a chimney depends upon the _______?

Height of the chimney

Neither A. nor B.

Density of the chimney gases

Both A. and B.

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