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Reviewer C > Checal Indiabix Himmel > Flashcards

Checal Indiabix Himmel Flashcards

1
Q

Higher efficiency in the combustion of solid fuel can not be achieved by

A

keeping the flue gas exhaust temperature very high.

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2
Q

A coal containing very high percentage of durain is called __________ coal.
bright

A

Splint

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3
Q

During combustion of gaseous fuels, deficiency of air

A

lengthens the flame

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4
Q

Gross and net calorific value of a fuel will be the same

A

if its hydrogen/hydrogen compound content is zero.

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5
Q

Low temperature carbonisation

A

is mainly for producing the smokeless domestic coke.

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6
Q

Size of blast furnace grade coke is __________ mm.

A

25-80

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7
Q

Presence of __________ in a dry gaseous fuel does not contribute to its calorific value.

A

Oxygen

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8
Q

The internal energy of the combustion products is __________ compared to that of reactants.

A

less

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9
Q

Junker’s calorimeter is used to determine the calorific value of

A

gaseous fuels

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10
Q

Combustion reaction of fuels is a/an __________ reaction.

A

Exothermic

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11
Q

Improper storage condition results in the weathering of coal and spontaneous combustion, which increases its

A

friability & oxygen content

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12
Q

Which of the following constituents of coal is the most important in the production of coke?

A

Carbon

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13
Q

Stack heat losses can be minimised by

A

controlling the excess air

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14
Q

Laboratory gas is obtained by the cracking of

A

Kerosene

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15
Q

Bituminous coal

A

Is generally coking and burns with smoky yellow flame

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16
Q

Ratio of primary air to secondary air increases with increase in the rank of coal, because the

A

ratio of fixed carbon to volatile matter increases.

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17
Q

Carbon Content by weight in air dried wood may be about __________ percent.

A

50

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18
Q

Gross & net calorific value is the same for

A

L.D. converter gas

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19
Q

Wobbe index’ is a characteristic of

A

Gaseous fuels

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20
Q

Presence of free moisture in coal during its high temperature carbonisation

A

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

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21
Q

Explosion limit of blast furnace gas is 37 to 71% gas in gas-air mixture. It means that the blast furnace gas will explode when burnt in a confined space, if its concentration in the gas-air mixture is __________ percent.

A

in between 37 & 71%

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22
Q

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

A

no possibility of obtaining complete combustion at high temperature.
always loss of heat from the flame.

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23
Q

Coke oven gas consists mainly of

A

H2, & CH4

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24
Q

Fuel gases containing hydrocarbons (ie.g. coke oven gas) are not preheated before burning, mainly because

A

the hydrocarbons crack thereby choking and fouling the heat transfer surface by carbon soot.

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25
Q

Which of the following is the most reactive (as regards the formation of CO + H2 from C + H2O) ?

A

Low temperature coke

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26
Q

Calorific value of coal middling generated in coal washeries during washing of coal may be around __________ Kcal/kg.

A

4000

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27
Q

Flue gas discharge velocity through chimney of a big thermal power plant may be around __________ m/sec.

A

10

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28
Q

Which of the following is used for making the explosive ‘TNT’ ?

A

Toluene

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29
Q

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

A

Fuel and air

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30
Q

Which of the following gaseous fuels has the lowest calorific value ?

A

Blast furnace gas

31
Q

Which of the following is not a by-product recovered in a high temperature coal carbonisation plant ?

A

Ethylene

32
Q

Pensky-Marten apparatus is used for those oils, whose flash points are __________ °F.

A

> 120

33
Q

In high temperature carbonisation of coal compared to low temperature carbonisation

A

H2 content in the coke oven gas is more.

34
Q

When incomplete combustion loss is high, the flue gas analysis shows large amount of

A

CO

35
Q

The gas which contributes maximum to the heating value of natural gas is

A

CH4

36
Q

The temperature at which plastic layer formation takes place during carbonisation of coal varies from __________ °C.

A

350 to 450

37
Q

Yield of coke oven gas in low temperature carbonisation of coal is about __________ Nm3 /ton of dry coal.

A

160

38
Q

Temperature of preheated air used for the transportation of pulverised coal through pipes to the burner of a boiler furnace is restricted to a maximum limit of about 300° C to avoid the

A

risk of explosion

39
Q

Blast furnace coke is made from coal

A

high temperature carbonisation.

40
Q

Yield of blast furnace gas is about __________ Nm3 /ton of pig iron.

A

2000

41
Q

Coke oven gas is stripped of its H2S and mercaptans content by

A

adsorption on bog iron bed.

42
Q

In Lurgi coal gasifier,

A

larger quantity of coal can be processed.

43
Q

Mineral matter content (M) and ash content (A) in coal are approximately related as

A

M = 1.1A

44
Q

When steam is passed over coal resulting in the endothermic reaction represent by, C + H2O = CO + H2, it is called the __________ of coal.

A

gasification

45
Q

Dry air requirement for burning 1 Nm3 of CO to CO2 may be around __________ Nm3.

A

2.4

46
Q

Degree of carbonisation of coal during coke making can be roughly judged by the __________ of the coke produced

A

volatile matter

47
Q

Ammonia content in raw coke oven gas is about __________ gm/Nm3.

A

15

48
Q

Coal is heated in absence of air for 7 minutes at a temperature of about __________ °C, during its volatile matter determination for proximate analysis.

A

950

49
Q

Quantity of coke oven gas produced by high temperature carbonisation of one ton of dry coal may be around __________ Nm3 .

A

300

50
Q

Coking coals are invariably

A

bituminous coals

51
Q

Which of the following accounts for maximum energy loss in a boiler ?

A

Flue gases

52
Q

Wine making involves a series of very complex reactions most of which are performed
by microorganisms. The starting concentration of sugars determines the final alcohol content
and sweetness of the wine. The specific gravity of the starting stock is therefore adjusted to
achieve desired quality of wine.
A starting stock solution has a specific gravity of 1.075 and contains 12.7 wt% sugar. If all the
sugar is assumed to be C12H22O11, determine
a. kg sugar/kg H2O
b. lb solution/ft3 solution
c. g sugar/L solution

A

a. .145 kg sugar
kg H20
b.67.1 lb soln
ft3 soln
c. 136 g sugar
L soln

53
Q

Gypsum (plaster of Paris : CaSO4
.
2H2O) is produced by the reaction of calcium
carbonate and sulfuric acid. A certain lime stone analyzes: CaCO3 96.89 %; MgCO3 1.41 %;
inerts 1.70 %. For 5 metric tons of limestone reacted completely, determine:
a. kg of anhydrous gypsum (CaSO4) produced.
b. kg of sulfuric acid solution (98 wt%) required.
c. kg of carbon dioxide produced.
(MW : CaCO3 100.1; MgCO3 84.32; H2SO4 98; CaSO4 136; MgSO4 120;
H2O 18; CO2 44)

A

a. CaSO4 produced -6600 kg CaSO4
b. Sulfuric acid required
Both CaCO3 and MgCO3 react with sulfuric acid in a 1 to 1 molar ratio. -4920 kg H2SO4 solution

c.Carbon dioxide generated - 2165 kg CO2

54
Q

The synthesis of ammonia proceeds according to the following reaction
N2 + 3 H2 —–> 2 NH3
In a given plant, 4202 lb of nitrogen and 1046 lb of hydrogen are fed to the synthesis reactor
per hour. Production of pure ammonia from this reactor is 3060 lb per hour.
a. What is the limiting reactant.
b. What is the percent excess reactant.
c. What is the percent conversion obtained (based on the limiting reactant).

A

a. 300 lb mol NH3 from N2
b. 16.2 %
c. 60.0 %

55
Q

Five pounds of bismuth (MW = 209) is heated along with one pound of sulfur to form
Bi2S3 (MW = 514). At the end of the reaction, the mass is extracted and the free sulfur
recovered is 5 % of the reaction mass. Determine
a. the limiting reactant.
b. the percent excess reactant. 2 Bi + 3 S —–> Bi2S3
c. the percent conversion of sulfur to Bi2S3.

A

a. S is the limiting reactant.
b. 14.9 %
c. 70.0 %

56
Q

Pure carbon is completely burnt in oxygen. The flue gas analysis is 70%CO2, 20%CO and 10%O2. The percent excess oxygen used is

A

0

57
Q

Oxygen percentage (by weight) in atmospheric air is

A

23

58
Q

The calorific value of ‘LPG’ (50% propane + 50% butane) is about __________ kcal/Nm3.

A

25,000

59
Q

Tar yield in the low temperature and high temperature carbonisation of dry coal may be respectively __________ percent.

A

10 & 3

60
Q

present in coal is not determined in its ultimate analysis.

A

Fixed carbon

61
Q

When the coal is heated in absence of air, it is called its

A

carbonisation

62
Q

Fusion point of coal ash generally varies from 1000 to 1700° C. Ash having fusion point less than __________ °C is liable to form clinker.

A

1100

63
Q

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 reminder going to CO, the Orsat analysis in volume percent is

A

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

64
Q

The average molecular weight of a flue gas having the composition by volume as CO2 = 25%, O2 = 25%, N2 = 50% will be

A

23

65
Q

The calorific value of natural gas is about __________ kcal/Nm3.

A

10, 000

66
Q

During its calorific value determination by bomb calorimeter, coal is combusted by

A

oxygen

67
Q

Which of the following fuel gases has the highest calorific value ?

A

LPG

68
Q

Blast furnace gas burns with a bluish flame, because of the presence of

A

CO

69
Q

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

A

25

70
Q

Purity of coke means that, it is high in carbon and low in

A

volatiles

71
Q

Largest constituent of blast furnace gas is

A

N2

72
Q

A good metallurgical coke should have very low

A

sulphur & phosphorous content

73
Q

Correct viscosity of furnace oil at the burner tip for proper atomisation is about 25 centistokes. To reduce the viscosity of high viscosity furnace oil (250 centistokes) to the correct atomisation viscosity (i.e. 25 cst), it should be preheated to about____°C.

A

105

Reviewer C (19 decks)

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