[Stoves] Torrified Pellets

alex english aenglish444 at gmail.com
Sun May 24 14:22:06 MDT 2015


Crispin,
A prof I know at Queens U. wants to make torrified sphere pellets that can
be pumped with water through pipelines, then separated.
A scalable biomass energy concept.

My comment to Dean related to the only combustion characteristic that would
be different  with torrified pellets from plane old wood pellets.
Flammability limits that I could test in my premix burner TLUD.  As Ronald
has already stated, differences I too doubt would show up in other
diffusion TLUDs.

The fuel matters, the stove matters, the price matters, the meal/task
matters, got it. I won't blame or credit the fuel alone, but charcoal
really is special :)

Alex

On Sun, May 24, 2015 at 3:13 PM, Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Alex
>
>
>
> The major reason to torrefy wood seems to be that it stops absorbing
> moisture (mostly) and it weighs less per MJ. The EU is importing a lot of
> pellets on this basis. The UK has a power station fired by them.
>
>
>
> Regards
>
> Crispin
>
>
>
>
>
>
>
> *From:* Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On
> Behalf Of *alex english
> *Sent:* Sunday, May 24, 2015 14:18
> *To:* Discussion of biomass cooking stoves
> *Subject:* Re: [Stoves] Torrified Pellets
>
>
>
> Torrified wood has most of it's volatiles.  I would expect the gases to
> have a higher CV and wider range of flame stability when used in a premix
> burner. Just guessing this has no relevance to cooking stoves.
> Dean, what is the range, cat pee best to worst PM emissions, that you have
> measured from any and all tluds when burning dry wood pellets?
> Alex
>
> On 2015-05-24 1:53 PM, "Dean Still" <deankstill at gmail.com> wrote:
>
> Dear Ronald,
>
>
>
> Thanks for your helpful comments. Charcoal without remaining wood in it
> doesn't make smoke but, of course, wood really likes to smoke. With biomass
> the preparation including recipe, drying, pellet size, etc. makes a big
> difference in emissions when trying to get down to the very low levels
> needed to protect health. I'm making some torrified pellets and will report
> back after testing under the hood.
>
>
>
> All Best,
>
>
>
> Dean
>
>
>
> On Sat, May 23, 2015 at 3:52 PM, Ronald Hongsermeier <rwhongser at web.de>
> wrote:
>
> Dear Dean,
> I may seem like I'm harping here, but now that you've said a bit more,
> you've mentioned a couple of factors that I have noticed in my limited
> experience without a hood and therefore without concrete parametric
> analysis, but for which I can give some postulates.
>
> 1. The wood-gas stove in design mode depends on a uniform fuel
> "chunk-size" which promotes a level "pyrolysis" front(planar) migrating
> towards the bottom of the stove. If that plane is broken by dis-uniformity
> in the fuel or overly large gaps between the fuel pieces, you will get a
> spot drop in temperature along with glowing fuel which will migrate
> unevenly towards the bottom of the stove, breaking the pyrolysis front and
> sometimes dropping the mean temp inside the burning chamber such that the
> rising wood gas will no longer be close enough to critical temp that the
> onset of 2nd-ary air will ignite it.
>
> 2. 1. would be consistent with the bark observation. Bark generally has
> lots more minerals and less energy per unit mass. Did you/they assure
> dryness level of the bark? Were the pieces between (cross-section/10-20) of
> the stoves throat? Do you mean pellets from eucalyptus wood or when
> eucalyptus oil is poured on the fuel? Off the shelf kerosin burners here in
> germany are strictly regulated as to what you may or may not burn in them.
> If it is smoking it is either wrong fuel, design flaw or user error.
>
> 3. Pellets pack closely, so if they are smoking, usually the problem can
> be fixed by either turning up the fan a bit or putting some chimney length
> between the secondary air and the pan to increase the draw. (i.e., the
> primary air is probably not of sufficient pressure to deliver enough O2 to
> the pyrolysis front to keep it hot enough such that it will ignite upon
> contact with the secondary air.)
>
> 4. Because torrefied pellets are partially reacted, they may be somewhat
> less dense and especially because the ends will be cleaner, they may not
> resist airflow as much, which may help somewhat with 3. above. I would
> expect them to act very similar to dry pellets, except for the difference
> in density.
>
> regards,
> Ronald von Aftermidnighttimeforantibiotics (and bed)
>
>
>
> On 23.05.2015 23:49, Dean Still wrote:
>
> Dear Ron,
>
>
>
> We had three women interns here at the research center for a summer who
> found cleaner burning recipes for the TLUDs gathered from the surrounding
> forest. Some things like bark make smoke, etc.
>
>
>
> Many pellets smoke when using eucalyptus, etc. Different mixtures of
> kerosene make more or less smoke in off the shelf stoves.
>
>
>
> I'm wondering if torrified pellets will burn cleaner than normal pellets.
>
>
>
>
>
> Best,
>
>
>
> Dean
>
>
>
> On Sat, May 23, 2015 at 1:28 PM, Ronald Hongsermeier <rwhongser at web.de>
> wrote:
>
> Hi Dean,
> I remember that there was a proposed university program (W. Virginia or
> the Carolinas??) In view of the deaths(not _many_ but tragic) that have
> taken place due to off-loading of pellets at some European ports (CO in the
> hold) The torrefaction could lead to a more inert fuel. That's hopeful
> speculation on my part however. You would be transporting some less bound
> water and the energy density is better than regular pellets in addition to
> the lack of liquid or vapor H2O absorption issue mentioned before-- these
> would lend efficiencies in the logistics end of things and an even more
> uniform fuel than regular pellets, which tend to absorb quite a  bit of
> water here in the damp winter weather...
> I have to admit that I'm a bit puzzled as to what you mean by cleaner fuel
> recipes. What specific pollutant are you interested in or are you talking
> about particulate?
> If you aren't choking the burn by putting the pot too close, you should be
> getting a very clean burn with a TLUD?!?
>
> regards,
> Ron
>
> On 23.05.2015 22:01, Dean Still wrote:
>
> Hi Ronald,
>
>
>
> I'll keep looking. I think that we shouldn't forget cleaner fuel recipes
> as part of the solution.
>
>
>
> Best,
>
>
>
> Dean
>
>
>
> On Sat, May 23, 2015 at 12:33 PM, Ronald Hongsermeier <rwhongser at web.de>
> wrote:
>
> Hi Dean,
> I did some searching around on the internet several years ago on this
> topic.
> I'd like to try torrefied stuff as well, but I struck out at that time.
> No idea where to find them.
> The main advantage that I picked up on at that time was that they should
> be relatively inert as to picking up extra water after they were pelletized.
> Cleaner burning than what?
> clean burning is a control issue, not a fuel issue as far as I understand.
> If I understand the concept correctly, it's like using part of the large
> molecules initially broken out (cracked) by the heat in the reaction vessel
> to coat the surfaces of the remaining unpyrolized material. This should
> burn quite okay in a TLUD.
>
> regards,
> Ronald von Nasennebenhöhlenhölle (but I'm coming back)
>
> On 23.05.2015 20:56, Dean Still wrote:
>
> Hi All,
>
>
>
> I'd like to try torrified pellets in a TLUD under the emissions hood.
>
>
>
> Any ideas on where to find them?
>
>
>
> Or if it should be cleaner burning?
>
>
>
> Best,
>
>
>
> Dean
>
>
>
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