[Stoves] Calc. void space and pellet particle density

Ronal W. Larson rongretlarson at comcast.net
Mon Mar 10 15:57:48 CDT 2014


Frank - see below:

On Mar 10, 2014, at 12:13 PM, Frank Shields <frank at compostlab.com> wrote:

> Ron and all,
>  
> Seems a few years back there was a University (or some group) that was going to assemble a collection of test methods for stoves? Was Tami involved? Did anything come of that?
>  
      [RWL:   Maybe there is a University that has been doing that, but I would guess that Dean Still, of all on this list, would know best.   Is a consultant with GACC.   I would also trust Jim Jetter of EPA, to know of such.   I don't.  
     Tami has an MS student, Ryan Thompson, doing tests on stove emissions, but probably not on fuels or stove efficiencies.

More below.

> See below:
>  
>  
>  
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Ronal W. Larson
> Sent: Sunday, March 09, 2014 5:17 PM
> To: Discussion of biomass
> Subject: Re: [Stoves] Calc. void space and pellet particle density
>  
> Frank:  (and anyone on list)
>  
>   1.  Would you be good enough to add a few more tests:
>  
> a.      Measure (ml or gm) the amount of water (and/or acetone) you can add to the container full of sand.  (I see relative density of .785 for acetone)
>  
> [Frank >] I like acetone because water can have air bobbles when measuring the density of grains of particles –like sand. So for particle density of sand you fill a container with water to get volume. Then fill with acetone to get the density of acetone. Then add sand and acetone together to get the particle density.

     [RWL:  I like the idea of adding this as a standard test, but am also asking you to repeat your earlier test with this use of sand and water/acetone. Presumably the new weight will be 20-30% higher than with the sand result you reported.   I think that your method has not accounted for the volume of air in either the sand or pellet case (no air volume of course with water alone).  Knowing this added sand/water and sand/acetone weight results will, I think, decrease your reported void volume.   Tightly packed spheres get above 70% volume (air void space less than 30%).  I think we might get close to that with pellets.   

	I don’t think I need the results with pellets and water or acetone, but would be nice to have.

	I think no issues with your other answers below, but the issue with wax seems worth thinking more about.]
>  
> b.     Same for sand replaced by pellets, even if the pellets are ruined  (but try to make the weight gain measurement as fast as possible (see how much you can both add and drain).  But perhaps they can be waterproofed with only a gram or two of waxy material.
> [Frank >]  -Official tests for soil requires to coat with wax and use water. Terrible – terrible. The wax leaks and add volume. The sand is better. The sand changes in bulk density when shaken (a problem) but the item being tested (wood chips, pellets, soil clod) do not change in particle size. So my thinking is to decrease the sand / sample ratio as much as you can. That is add the most pellets to the liter bottle as possible and get them to be embedded into the sand.   
>            
> c.      Same when you mix sand and pellets  (my preference is to start with a liter of only pellets, then first see how much sand you can get in [by shaking], weigh and then see how much water (and or acetone) can be added).
> [Frank >] I do this for wood chips and suggest for large particles like the cubes being talked about. Fill a container to the top to get bulk density then pour in the sand with lots of tapping. Take out the wood pieces and determine the reduction volume of the sand (= voids). But for smaller particles I suggest embedding the particles in the sand to make sure there are no big pockets of voids. If you keep tapping the sample will float to the top. So for wood chips and sticks I add sand and chips together and make sure there is plenty of sand on top. Then tap until I see the first sigh of sample pocking through the top. Then I know the particles are all surrounded with sand.
>  
>   2.  I agree with Andrew Heggie that a void space of 52% sounds high.  Can you specify the diameter of the pellets and an average pellet length.  Manufacturer?  Any spec on source material?
> [Frank >] This was a quickly conducted test using a real sample but without all the QC usually done for the sole purpose of showing an example of how to do the test.
>  
>   3.  If you have to start over, let’s use a volume of “exactly” 1 liter (water weight = 1 kg), for all cases (to simplify the computations).
> [Frank >]
> http://www.novatech-usa.com/Products/Glass-BOD-Bottles
> http://www.hach.com/disposable-bod-bottles-300-ml-100-cs/product?id=7640237102
>  
> One liter volumetric flask is not easy to use for such tests. Nice to fill to top and determine that volume. I like BOD bottles for using with acetone or water for testing the particle density of very small particles. Eye dropper removes the excess to exact. I use glass but they are expensive. The disposable ones are made of a plastic and I will work for water but may not(?) with acetone (or other solvents).  
>  
> I use imhoff cones for wood chips and sticks. Add sticks or chips to a couple inches from top. Pour in sand and tap, tap, tap until the chips poke out of the surface. See total volume from marks on side. Pour out the sand and collect. Dump wood. Pour back sand, tap, tap, tap and see volume of voids.
>  
> http://www.coleparmer.com/buy/product/56354-imhoff-settling-cone-plastic-each-w990800.html
>  
>   4.  We should be able to get the same answer for pellet density regardless of how hard we try to increase the bulk densities (Alex’ point).  
> [Frank >] Pellet density but not necessarily pellet bulk density. Depends on packing.
>  
> Thanks in advance.
>  
>  
> Ron
>  
> On Mar 8, 2014, at 3:53 PM, Frank Shields <frank at compostlab.com> wrote:
> 
> 
> 1555.68
> sand
> 1053.17
> water (vol)
> 671.78
> pellets
> 152.47
> pellets used
> 1539.82
> Pellets + Sand
> 0.637865
> Bulk density Pellet
> 671.78/1053.17
> 1.47714
> Sand bulk density
> 1555.68/1053.17
> 1387.35
> Sand used when mixed with pellets
> 1539.8-152.47
> 168.33
> Sand not used
> 1555.68-1387.35
> 113.9567
> Vol sand not used
> 168.33/1.477
> 1.337965
> pellet density
> 152.47/113.95
> 502.091
> pellet vol in bottle
> 671.78/1.337965
> 551.079
> void space
> 1053.17-502.091
> 52.32574
> % voids
> 551.079/1053.17*100
> Tare a glass narrow neck bottle
> Fill with sand –weigh
> Fill with pellets weigh
> Fill with water – weigh (vol of glass jar)
> Calc bulk density of sand and pellets
>  
> Weigh a handful of pellets
> Add sand > sprinkle in pellets > add sand > sprinkle in pellets until all pellets are in bottle and topped off with sand
> Weigh sand + pellets mix
> Calc sand in mix
> Calc sand NOT in mix
> Calc volume of sand NOT in mix using sand bulk density
> Calc. particle density of pellets from wt hand full of pellets / volume of sand not in mix.
> Calc pellet volume in liter bottle when filled with pellets
> Calc. void space in bottle left
> Calc percent voids from void / total vol of liter bottle X 100
>  
> I fill with sand then tap twice on the counter then top off with sand.
>  
> This is a sample from a local US pellet source. The bulk density is 0.638 g/cc and the particle density of the pellets is 1.338 g/cc
> Void space for air movement in a TLUD filled with these pellets is 52.3%
>  
> Instead of sand one can use water or acetone for other materials. The particle density of sand (or like) I find best done using acetone.  
>  
>  
> Hope the calcs are correct. : )
>  
> Regards
>  
> Frank
>  
>  
> Frank Shields
> Control Laboratories; Inc.
> 42 Hangar Way
> Watsonville, CA  95076
> (831) 724-5422 tel
> (831) 724-3188 fax
> frank at biocharlab.com
> www.controllabs.com
>  
>  
>  
>  
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Dean Still
> Sent: Thursday, March 06, 2014 11:21 AM
> To: Discussion of biomass cooking stoves
> Subject: Re: [Stoves] Cuber and size of densifying machines. (no longer Re: The wood and char and fuel "debate" )
>  
> Hi Tom,
>  
> In Uganda the pellets were too dense and were hard to light. Do you know the density of USA heating stove pellets?
>  
> Best,
>  
> Dean
>  
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