[Gasification] [Bioenergy] HHV from composition

Sat Jul 14 13:40:50 EDT 2007

Thomas,

thank you very much for Your message.

I've done a few calculation using data from Biobib and Phyllis databases
and, to my surprise, Channiwala 's formula wasn't that precise!
I send as attachment the file I created for these calculations: I underline
that all data in a column come from the same source.

The average error in column "S" states that Channiwala and Vondracek are
almost of the same precision.
The most probable explanation is: some data are wrong in the database - if
it's so, please write the correct ones in my file.

Thank you in advance

best regards
Francesco Murer

2007/7/4, Thomas Reed <tombreed at comcast.net>:
>
> 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 - 0.0211Ash
> >
> > 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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