Values in heat of combustion plugin doesnt make sense

[Michael Jensen]

Hi everyone.

I have entered a syngas stream (22% CO, 36%H2, 35%CO2, 1,3%CH4, 5,5%H2O, 0,2%N2) and wanted to know the heat of combustion for the stream.

The calculated value of 702,6 kJ/kg and 11271 kJ/kmol doesnt make sense. I can understand if there is a typo and it is 11271 kj/nm3... Do others get values that make sense?

Br
Michael

[Frank R Brown III]

Using Data from the NGPSA Data Book I found the stream to be 7505.76 kJ/kg. Incidently speaking of typos I assumed 0.2% N2 from 0.02 to make the total 100%.

[Michael Jensen]

Thanks Frank. I updated the original post. I get similar value. There most be something wrong with the calculation in DWSIM

[Daniel Medeiros]

This is the calculation procedure: https://github.com/DanWBR/dwsim/blob/windows/DWSIM.Plugins.HeatOfCombustion/Form1.vb#L44

It takes into account the combustion of hydrocarbons only. Maybe you can help me to spot the error.

[Michael Jensen]

Hi Daniel.

I guess this is the error:

If compounds(i).Elements.ContainsKey("C") And compounds(i).Elements.ContainsKey("H") Then...

If the stream contains either hydrogen or carbon monoxide it doesnt calculate a heating value.

If only hydrocarbons are used in the calculation, I would rename the plugin to "Hydrocarbon combustion" or something else. The user is not notified that it only uses hydrocarbons..

[Daniel Medeiros]

what are the combustion reactions for them?

[Michael Jensen]

H2 + 1/2 O2 -> H2O
CO + 1/2 O2 -> CO2
2 NH3 + 1,5 O2 -> N2 + 3 H2O
H2S + 1,5 O2 -> SO2 + H2O
COS + 1,5 O2 -> CO2 + SO2

[Michael Jensen]

CS2 + 3 O2 -> CO2 + 2 SO2