[Stoves] BIOMASS ENERGY VS COMPOSITION

[frank]

Dear Tom, and Stovers,

There needs to be a lot more work to see if my idea is repeatable to a 
point it means something we can use. I like the idea of just using 
moisture and carbon to determine the energy in the fuel and guess at 
hydrogen because I find the carbon analyzer being very accurate where 
the few times I have sent out samples with reps to another lab for 
calorimeter work the results were varied more than I like. We need to at 
least consider the ash in fuels and I think also the energy in glues, 
oils, greases, resins etc.  when we come to testing biowaste products etc.

It was your web site where I got the energy info of the different fuels 
that made me think we need another method. It seems we can use 6% 
hydrogen for fuel and 2% hydrogen for charred fuel on an ash-free basis.

I just received today a bag of ground soybean hulls and ground almond 
shells for other testing.  We get a wide variety of materials sent to 
this lab that could be used for experimenting for the potential of being 
a small fuel or glue.  If only I had more time and could work on this 
full time. It will be awhile before I can get back to it. 

Kindest regards

Frank
 




Thomas Reed wrote:

> Dear Frank:
>
> I'm glad to see someone exploring alternate biomass fuels here. at 
> STOVES and GASIFICATION.  Mother Nature produces  biomass in many 
> forms beside  wood, and they are all potentially good for making 
> energy or charcoal, each with some reservations. 
>
> It is important to report both particle density and the buld density 
> under various packing conditions.  Many of the measurements you 
> project can be done with simple apparatus, but HHV and ultimate 
> analysis will cost a bundle.  Fortunately, Mother Nature is quite 
> conservative in building her various biomass forms and the variation 
> is limited.  For a long time I have used the average formula
>
> C H1.4 O0.6
> The molecular weight for this formula is 23; the energy content is 21 
> MJ/kg (high heating value, HHV, bone dry) or 19 MJ, (low heating 
> value, LHV (liquid water not condensed) with  10% moisture (Denver dry).
>
> This covers most structural biomass (wood, straw etc.)  You can see an 
> extensive listing of properties at our WoodGas site, 
> http://www.woodgas.com/proximat.htm  
> <http://www.woodgas.com/proximat.htm>along with links to other listings. 
> ------------------------------------------------------------------------
>
> However, I have discovered important exceptions in "reproductive" 
> biomass (cobs, seeds, husks, shells, ....) which are also good fuels, 
> particularly for our woodgas stoves.  Reproductive biomass could be 
> over 50% of the available biomass residues in the world, since in the 
> past they have not found a use. 
> Fortunately, there are corellations between the simple proximate 
> analysis and the ultimate analysis. 
>
> I discovered the importance of this second category when working with 
> Acai pits from Brazil and Cherry pits (8 tons of each).  The proximate 
> analysis of the Acai pits was very close to being pure starch with an 
> energy content of 16 MJ/kg (HHV), while the cherry pits had 23 MJ/kg 
> HHV, both outlyers of the above assumptions.  Reproductive biomass 
> contains vey little lignin and lignin has an energy content of ~26 
> MJ/kg.  Starch ((C6H10O5)n has an energy content of  ~17 MJ/kg.  
> Triglycerides (vegetable oils) have an energy content of ~ 40 MJ/kg, 
> so it doesn't take much oil tucked away in the seed to kick up the 
> energy content.  
>
> I hope you will continue your investigation and let us all know the 
> results.
>
> Yours truly,
>
> TOM REED       THE BIOMASS ENERGY FOUNDATION
>
> frank wrote:
>
>>Stovers,
>>
>>The WBT relies on the energy (joules) used during the test. Determined 
>>in the starting fuel energy and subtracting the fuel energy remaining.
>>Because we may be using it with a mix of different woods, small fuels 
>>like nuts and berries, leaves, dung and all types of organics we need a 
>>good simple method of determine the energy output of any type of fuel.
>>
>>I am trying to come up with such a procedure.
>>
>>If one takes a block of wood 10 X 10 X 10 cm and drops it onto a fire it 
>>does three things (as I understand it):
>>1) moisture goes off
>>2) turns to carbon
>>3) then, finally, the size is reduced as the carbon oxidizes until there 
>>is only ash remaining.
>>
>>The particle density is reduced as the moisture and wood gases go off 
>>and remains the same during the carbon to ash phase until the ash is 
>>heavy enough to increase the density.
>>
>>If we know some things about a fuel at the start like:
>>1) moisture
>>2) ash content
>>3) joules per kg ash-free volatile solids
>>4) joules per kg ash-free charred
>>5) particle density ash-free volatile solids
>>6) particle density ash-free charred fuel
>>
>>
>>Then when testing a stove we can start with a 1) known weight of fuel. 
>>After the test at the end we 2) weight what is left and determine the 3) 
>>particle density of the wood-char-ash mix.  We can then calculate the 
>>Joules we started with and the joules left over at the end. 
>>
>>For my testing I have replaced the Joules with Carbon because I  have a 
>>Leco carbon analyzer.
>>
>>If you wanted to test a stove using a type of fuel you would send in a 
>>sample to a lab and have the following test done:
>>Example:
>>
>>Moisture % 28.6
>>Volatile solids dry wt 99.2%
>>Ash dry wt 0.77%
>>Particle Density of fuel (ash-free dry wt) g/cc 0.75
>>Particle Density charred sample (ash-free) g/cc 0.61
>>Carbon  in ash-free volatile solids g/cc 0.38
>>Carbon in ash-free char g/cc 0.45
>>(char is produced in preheated oven 400 deg. C sample covered for one hour)
>>
>>example as we go.....
>>tare 153.25
>>tare + sample wet 191.65
>>tare + sample dry 180.68
>>tare + sample charred 162.34
>>tare + sample ashed 153.46
>>
>>
>>For the stove tester using the above fuel:
>>weigh the amount of fuel starting  2000g
>>calculate volatile solids dry wt by subtracting water and ash. 1413 g
>>weigh the wood-char-ash at the end. 400g
>>determine particle density (easy test)  0.65
>>calculate ash-free particle density and plot on the line between 
>>(wood-carbon) and (char-carbon) from data received to get the carbon 
>>(Joules) in the cubic centimeter.0.430 Carbon (g)/cc
>>calculate total carbon left  1413/0.65 = 2173cc.     2173 X 0.43 = 934  
>>grams carbon left.
>>If the density of the remaining mix from the stove test is between the 
>>wood - char density values above (a mixture of wood+char remain) use 
>>that plotted value for the energy not burned. If the density of the 
>>remaining material is at (or less) than the char density value use the 
>>char value as the energy.
>>
>>I have been working on 6 samples:
>>1) Shredded bark
>>2) almond tree trimming
>>3) cow manure
>>4) Pellets of sewage
>>5) paper and fruit juices
>>6) wood chips
>>
>>Open to any help or suggestions.
>>
>>Getting a little 'burned out'!
>>
>>Frank
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-- 
Frank Shields
Soil Control Lab
42 Hangar way
Watsonville, CA  95076
(831) 724-5422 tel
(831) 724-3188 fax
frank at compostlab.com
www.compostlab.com