[Gasification] [Bioenergy] HHV from composition

[Thomas Reed]

Dear All:

While a lot of gasification and stoves is concerned with mechanical 
problems, the thermodynamics and chemistry underlie all our activities.  
I am blessed or cursed with being a Physical Chemist and have spent my 
life and careers in high temperature work.  I am so happy to be able to 
give an exact answer to the question below. 
------------------------------------------------------------------------

The high heating value, HHV, for any fuel is a very important commercial 
property and so it is measured with great accuracy.  It is not 
surprising that various scientists have tried to correlate the HHV to 
the composition starting with Dulong in 1880.  Most of the equations 
below were developed primarily for coal, but some for MSW, biomass etc. 

In 1990 a student of Prof. Parikh,  S. A. Channiwala  IIT Bombay 
(Mumbai) wrote a thesis that covered all previous correlations and added 
further data of his own which covered all fuel-like substances.  A 
summary of this work by S. A. Channiwal and P. P. Parikh appeared in 
FUEL, _81_ , 1051-1063 and recommends the last correlation which you 
give below:

HHV [kJ/kg] = 349,1 C + 1178,3 H - 103,4 O + 100,5 S - 15,1 N - 21,1 Ash

To quote their abstract, "The correlation offers an average absolute 
error of 1.45% and a bias error of 0.00%."    They also note in the body 
of the text that "the ASTM bomb calorimeter standards speciy the 
reproducibility limit of 240J/g while the present correlation for the 
entire range of solid, liquid and gaseous fuels offers the predictin 
within 337J/g which is quite comparable with the measurement 
uncertainties if one considers the widely varying nature of data and the 
source of its collection."

I am currently writing a sequel.

(Personal note:  I visited Prof. Parikh in 1990 and she sent me on a 
trip to Pune and Phaltan with Channiwala as my guide and companion.  We 
had LOTS of time to talk about Walruses and Kings and Thermodynamic 
Things.)

Yours truly,  

TOM REED         BEF/BEC

P
Francesco Murer wrote:
> I've found many formulas to estimate HHV of biomass from ultimate analysis. 
> I 'd like to know 
>
> *	which is the most accurate for woody biomass?
> *	on which basis I should consider elements mass fractions: dry-ash-free or dry or "as received"? 
>
>
> Bain/Graboski (1979):
> HHV [Btu/lb] = 85,65 +137,04 C + 217,55 H + 62,56 N 107,73 S  + 8,04 O - 12,94 Ash
>
> Dulong-Petit (Perry, 1997)
> HHV [kJ/kg] = 337 C + 1428 (H - O/8) + 95 S
>
> Dulong-Petit (Tillman)
> HHV [Btu/lb] = 14490 C + 61000 H + 5550 S
> HHV [Btu/lb] = 14440 C + 61020 H + 5550 S - 6590 O - (39 O)^2       -- hydrogen and oxygen in the moisture content are reported in H and O of the ultimate analysis -- 
>
> Dulong-Berthelot (Tillman)
> HHV [Btu/lb] = 81,370 + 345 [ %H - (%O + %N - 1) / 8 ] + 22,2 %S   -- where the fuel contents of H, O, N, S are expressed on a percentage, rathere than weight fraction basis --
>
> Boie (Standard and modified for MSW respectively)
> HHV [kJ/kg] = 351,7 C + 1162,4 H + 104,6 S - 110,9 O + 62,8 N - 439,6 
> HHV [kJ/kg] = 227,9 C + 1162,4 H + 104,6 S + 58,2 O + 62,8 N - 439,6
>
> Vondracek
> HHV [kcal/kg] = 85 C + 270 H +25 S - 27 O 
> HHV [kcal/kg] = (89,1 - 0,067 C) + 270 H + 25 S - 27 O 
>
> IGT/Graboski
> HHV(kJ/g) = 0.341 C+ 1.322 H + 0.0686 S - 0.120 (O+N) - 0.0153 Ash
>
> Atlas of Thermal Data (NREL/TP-433-7965)
> HHV(kJ/g) = 0.3491 C + 1.1783 H + 0.1005 S -0.1034 O -0.0151 N - 0.0211 Ash
>
> Channiwala
> HHV [kJ/kg] = 349,1 C + 1178,3 H - 103,4 O + 100,5 S - 15,1 N - 21,1 Ash
>
>
> Besides these, there should be also formulas by Mott and Spooner, Grummel and Davis, but I haven't been able to found them. 
>
>
> Thanks in advance for any reply,
>
> best regards
>
> Francesco Murer
>
>   
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