3 replies to this topic

[chemic]

Hi all,

How can I calculate Gross Calarofic Value (GCV) from Proximate Analysis of Fuel,

Also, I need the Relationship between Proximate and Ultimate Analysis

Regards,

Chemic

[El Compostador]

Chemic: proximate analysis reports gravimetric fractions (weight percentages) of moisture (H2O), volatile matter (fuel), fixed carbon, etc. In an ultimate analysis, fractions are reported at the elemental level; for example, the hydrogen bound to the water molecule is reported together with the hydrogen in the fuel.

If you have the ultimate analysis and would like to know the available hydrogen, then you would have to subtract the amount of hydrogen bound to water; assuming that all the oxygen in the fuel is in the form of water then you would use:

GH available = GH, total – GO/8. where G refers to a weight percentage, H =hydrogen, O =Oxygen.

As far as calculating the GCV, it depends on the type of fuel (the heating value of the fuel); what type of fuel are you considering? you can also estimate it using the ultimate analysis but you need to know the type of fuel.

Hope this helps a bit.

[chemic]

Thanks EI.

I don't have Ultimate Analysis, hence I need to estimate GCV using Proximate Analysis,

The fuel used is a Biomass Material (Rice Husk, Wood Chips etc).

I have the following relationship between proximate and Ultimate Analysis, i.e Calculation of % of Carbon, Hydrogen and Nitrogen from Fixed Carbon, Ash, Moisture and Volatile matter (proximate analysis), But I need to Know the Calculation of % Sulphur and % of Oxygen from Proximate analysis to Calculate GCV.

Regards,

Chemic

[MMA]

Chemic: For discussion purposes, let's assume the following proximate analysis:

Fixed Carbon kg

14

Volatile Matter kg

57

Ash kg

19

Moisture kg

10

TOTAL kg

100





If sulfur was not reported separately, it means it was not measured so you can't really calculate from the above information. You can approximate it if you have an idea of the chemical composition of the fuel and of the ash (mostly SiO2, Al2O3). The same goes for nitrogen. For example for rice hauls, we can assume a "chemical formula" for the volative matter such as:

C62H100O46NS.5P.7

Then you can assume that the 57 kg of volatile matter in the proximate analysis is due to C62H100 O46 N S.5 P.7 and calculate the elemental contributions. You can even calculate the heat of combustion using the above "chemical formula" and estimate the GCV. See the following link for more details:

http://www.woodgas.com/proximat.htm



But I am not sure if this type of analysis will help you since it involves using an estimate of the chemical compositon of your fuel and this is what you were trying to calculate in the first place!