[Stoves] Torrified Pellets

Mon May 25 10:12:29 CDT 2015

Hi Alex,

The best TLUD with a fan patterned after the Tom Reed design, using a clean
burning brand of heating stove pellets, started with alcohol gel, seemed to
do better than the new WHO standard of less than 2mg/min of PM 2.5. But
most well tuned TLUDs we test are approximately around 4 to 10. And the
untuned TLUD, of course, can be much worse. This is from gravimetric
testing which catch a lot more PM2.5 than light scattering tests. The
ISO/IWA requires gravimetric testing.

Well made charcoal burns without significant emissions of PM 2.5 and a
charcoal stove met the WHO PM2.5 standard.

Using 'real wood' is a bigger challenge. Not as clean yet. But dedicated
TLUDers are experimenting diligently!

Best,

Dean

On Sun, May 24, 2015 at 11:18 AM, alex english <aenglish444 at gmail.com>
wrote:

> 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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