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Combustion Analysis Problem

combustion mass balance chemical reaction

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#1 RPD


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Posted 14 September 2019 - 03:54 PM

Hello, I am currently stuck on a combustion analysis problem. The answer wanted is the composition of each stream. I have done it by setting up a table and using my combustion equations and assigning a variable to each equation. Somewhere I am making a mistake as when I solve all my equations I keep getting a negative kmol out for CO.


The coal contains 4.41% bound moisture


The question is attached. Any help will be much appreciated. My basis used is 100 kg coal in. 


Thanks in advance 


Adding on, sorry about how messy my work is. I hope it makes sense. I decided to first work out how much carbon actually combusted. I then wrote up all my combustion equations giving each a variable and using stoichiometric ratios. 


The gen 1 stands for generated in reaction 1 and con 1 stands for consumed in reaction 1. 


there is no extra information about the percentages and the CO2 relative to CO. No O2 is said to leave at the flue gas. 


According to my working there is negative kmol CO leaving which is obviously wrong.

Attached Files

Edited by RPD, 15 September 2019 - 03:53 PM.

#2 Bobby Strain

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Posted 14 September 2019 - 06:15 PM

We can't help you without seeing your work.



#3 breizh


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Posted 15 September 2019 - 03:10 AM

Hi ,

is your Problem statement complete ? no clue about CO2 or CO?

What about the % , no indication about mass or Mo l ?


We are not doing home work but we will support you if you explain to us your difficulties and show your  work.

Good luck.


#4 breizh


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Posted 15 September 2019 - 07:54 PM

Hi ,

Your documents are difficult to follow :

You should start with a PFD ( identify all the equipment) , label all the streams in and out .

Consider also to issue a Excel table to perform your calculation

list all the components

Use the analysis on hands and explain what you are getting from them .

write down all the possible reactions taking place .


note : about bound Moisture , this will be released during the calcination of the coal . This water will be combined with the water from the air and released in the flue gas.

Make sure you understand the meaning of volatile in Coal with the respective components..



If you follow this methodology everyone will understand your work .

Hope this is helping you .

Good luck


Edited by breizh, 16 September 2019 - 01:24 AM.

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