Hello
I am trying to calculate the stoichiometric air requirement for coal combustion.
I have a small question regarding combustion of coal.
Ultimate analysis for Coal as fired on wt basis%
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Posted 12 January 2015 - 07:37 AM
Hello
I am trying to calculate the stoichiometric air requirement for coal combustion.
I have a small question regarding combustion of coal.
Ultimate analysis for Coal as fired on wt basis%
Posted 12 January 2015 - 11:31 AM
There is no H2 or O2 or N2 present in coal. So use H, O, N so as not to look foolish.
(It makes no difference though, because the burning of 1 kg of H and then burning of 1 kg of H2 both require the same kgs of O2)
Burning of Coal can better written as: CxHyOzNpSq + ....... O2 --> ...................
in which x, y, z, p and q you can determine from the given composition.
Edited by PingPong, 12 January 2015 - 11:35 AM.
Posted 12 January 2015 - 12:26 PM
Thanks for the clarity. sorry I assumed few things in a different way.
IS there any changes required for the following calculations. If I know O as 10.5% in the Coal
Total actual O2 = Theoretical O2 required - Oxygen already in coal
Posted 12 January 2015 - 01:44 PM
That 10.5 % is WEIGHT %
1 kg O is equivalent to 1 kg O2
Posted 13 January 2015 - 04:04 AM
Thanks for your answers.
Posted 13 January 2015 - 11:49 PM
H2 + O = H2O
2 gm of hydrogen reacts with 16 gm of oxygen
Or, 1 gm of hydrogen reacts with 8 gm of oxygen
So, 5.4 gm of hydrogen (present in 100 gm of coal) reacts with 5.4 x 8 = 43.2 gm of oxygen
C + O2 = CO2
12 gm of carbon reacts with 32 gm oxygen
So, 73 gm of carbon will react with 32 x 73/12 = 194.7 gm of oxygen
And so on
Then combine all oxygen required and subtract oxygen present in coal. This would be oxygen required by 100 gm of coal for stoitiometric combustion. Convert the result obtained to air equivalent.
Add 20% more to the requirement (excess air) for complete combustion. Otherwise part of carbon will be converted to carbon monoxide instead of carbon dioxide. (There by some energy would be lost in the gases due to incomplete combustion)
Hydrogen and nitrogen can also be present in the volatile matter of the coal
Hope this answers your queries.
Edited by P.K.Rao, 14 January 2015 - 12:33 AM.
Posted 16 January 2015 - 10:11 AM
Thanks for your detailed reply Mr.Rao
I was adding N from coal on to the N2 from air.
I will consider NO2 as 1.5% into my combustion calculation.
Thanks
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