[Stoves] Calc. void space and pellet particle density

[Frank Shields]

Dear Crispin,

 

Yes - this is the type of thing I am looking for. They need to be heavy
enough to flow down around funny looking particles. And cheap to discard
after each test. Perfectly round would help as I think that is the only
problem with sand once the salts are removed. Stainless shot I was thinking
but likely too expensive. Steel shot picked out with a magnet but if they
acted like little magnets they would be no good. 

 

Glass beads do not flow like I need them for wood chips and all the
crevices. 

 

Regards

 

Frank

 

 

 

 

 

 

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Crispin Pembert-Pigott
Sent: Monday, March 10, 2014 2:19 PM
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] Calc. void space and pellet particle density

 

Dear Frank

 

One of the best ways to check voids is to use xenospheres
<http://www.freepatentsonline.com/5980644.html> . You would probably want to
measure their volume not the mass because they are so light. They are
available 'sized' for example 100 microns. One company selling them was
called Ash Resources in Johannesburg but I bet you can get them from a lot
of places.

 

Xenospheres are produced when tiny silica grains are expanded in the fire of
a coal burner like a power station
<http://www.darcy.co.uk/case-studies/installation-of-debris-booms-prevents-x
enospheres-getting-into-local-rivers/> .  They chill and emerge as hollow
spheres with a vacuum inside. They are floated off in the ash treatment and
collected, size sorted and sold as filler.

 

If you don't break them (they are not very strong) you have small balls that
are very slippery and pretty constant in size. You can buy, for example,
80-100 microns in a bag.

 

I think the biggest size is 400 microns but they do get larger - just not so
many of them. Light, insulating concrete products include it in the mix as
if it was sand. You can add them to ceramics to make them light but most
will not survive passing through a pug mill or extruder.

 

Regards

Crispin

 

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