Checal Indiabix Himmel Flashcards
Higher efficiency in the combustion of solid fuel can not be achieved by
keeping the flue gas exhaust temperature very high.
A coal containing very high percentage of durain is called __________ coal.
bright
Splint
During combustion of gaseous fuels, deficiency of air
lengthens the flame
Gross and net calorific value of a fuel will be the same
if its hydrogen/hydrogen compound content is zero.
Low temperature carbonisation
is mainly for producing the smokeless domestic coke.
Size of blast furnace grade coke is __________ mm.
25-80
Presence of __________ in a dry gaseous fuel does not contribute to its calorific value.
Oxygen
The internal energy of the combustion products is __________ compared to that of reactants.
less
Junker’s calorimeter is used to determine the calorific value of
gaseous fuels
Combustion reaction of fuels is a/an __________ reaction.
Exothermic
Improper storage condition results in the weathering of coal and spontaneous combustion, which increases its
friability & oxygen content
Which of the following constituents of coal is the most important in the production of coke?
Carbon
Stack heat losses can be minimised by
controlling the excess air
Laboratory gas is obtained by the cracking of
Kerosene
Bituminous coal
Is generally coking and burns with smoky yellow flame
Ratio of primary air to secondary air increases with increase in the rank of coal, because the
ratio of fixed carbon to volatile matter increases.
Carbon Content by weight in air dried wood may be about __________ percent.
50
Gross & net calorific value is the same for
L.D. converter gas
Wobbe index’ is a characteristic of
Gaseous fuels
Presence of free moisture in coal during its high temperature carbonisation
protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls.
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.
in between 37 & 71%
Actual flame temperature is always lower than the adiabatic flame temperature, because there is
no possibility of obtaining complete combustion at high temperature.
always loss of heat from the flame.
Coke oven gas consists mainly of
H2, & CH4
Fuel gases containing hydrocarbons (ie.g. coke oven gas) are not preheated before burning, mainly because
the hydrocarbons crack thereby choking and fouling the heat transfer surface by carbon soot.
Which of the following is the most reactive (as regards the formation of CO + H2 from C + H2O) ?
Low temperature coke
Calorific value of coal middling generated in coal washeries during washing of coal may be around __________ Kcal/kg.
4000
Flue gas discharge velocity through chimney of a big thermal power plant may be around __________ m/sec.
10
Which of the following is used for making the explosive ‘TNT’ ?
Toluene
Adiabatic flame temperature of a fuel is dependent on the initial temperature of
Fuel and air
Which of the following gaseous fuels has the lowest calorific value ?
Blast furnace gas
Which of the following is not a by-product recovered in a high temperature coal carbonisation plant ?
Ethylene
Pensky-Marten apparatus is used for those oils, whose flash points are __________ °F.
> 120
In high temperature carbonisation of coal compared to low temperature carbonisation
H2 content in the coke oven gas is more.
When incomplete combustion loss is high, the flue gas analysis shows large amount of
CO
The gas which contributes maximum to the heating value of natural gas is
CH4
The temperature at which plastic layer formation takes place during carbonisation of coal varies from __________ °C.
350 to 450
Yield of coke oven gas in low temperature carbonisation of coal is about __________ Nm3 /ton of dry coal.
160
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
risk of explosion
Blast furnace coke is made from coal
high temperature carbonisation.
Yield of blast furnace gas is about __________ Nm3 /ton of pig iron.
2000
Coke oven gas is stripped of its H2S and mercaptans content by
adsorption on bog iron bed.
In Lurgi coal gasifier,
larger quantity of coal can be processed.
Mineral matter content (M) and ash content (A) in coal are approximately related as
M = 1.1A
When steam is passed over coal resulting in the endothermic reaction represent by, C + H2O = CO + H2, it is called the __________ of coal.
gasification
Dry air requirement for burning 1 Nm3 of CO to CO2 may be around __________ Nm3.
2.4
Degree of carbonisation of coal during coke making can be roughly judged by the __________ of the coke produced
volatile matter
Ammonia content in raw coke oven gas is about __________ gm/Nm3.
15
Coal is heated in absence of air for 7 minutes at a temperature of about __________ °C, during its volatile matter determination for proximate analysis.
950
Quantity of coke oven gas produced by high temperature carbonisation of one ton of dry coal may be around __________ Nm3 .
300
Coking coals are invariably
bituminous coals
Which of the following accounts for maximum energy loss in a boiler ?
Flue gases
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. .145 kg sugar
kg H20
b.67.1 lb soln
ft3 soln
c. 136 g sugar
L soln
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. 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
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. 300 lb mol NH3 from N2
b. 16.2 %
c. 60.0 %
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. S is the limiting reactant.
b. 14.9 %
c. 70.0 %
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
0
Oxygen percentage (by weight) in atmospheric air is
23
The calorific value of ‘LPG’ (50% propane + 50% butane) is about __________ kcal/Nm3.
25,000
Tar yield in the low temperature and high temperature carbonisation of dry coal may be respectively __________ percent.
10 & 3
present in coal is not determined in its ultimate analysis.
Fixed carbon
When the coal is heated in absence of air, it is called its
carbonisation
Fusion point of coal ash generally varies from 1000 to 1700° C. Ash having fusion point less than __________ °C is liable to form clinker.
1100
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
CO2 : 7.42, CO : 1.86, O2 : 4.64, N2:86.02
The average molecular weight of a flue gas having the composition by volume as CO2 = 25%, O2 = 25%, N2 = 50% will be
23
The calorific value of natural gas is about __________ kcal/Nm3.
10, 000
During its calorific value determination by bomb calorimeter, coal is combusted by
oxygen
Which of the following fuel gases has the highest calorific value ?
LPG
Blast furnace gas burns with a bluish flame, because of the presence of
CO
Of the total tar present in raw coke oven gas, the tar recovered in primary cooler is about __________ percent.
25
Purity of coke means that, it is high in carbon and low in
volatiles
Largest constituent of blast furnace gas is
N2
A good metallurgical coke should have very low
sulphur & phosphorous content
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.
105
