[Stoves] Torrified Pellets

Mon May 25 23:09:02 CDT 2015

Alex,

The recent TLUD tests have been with pellets but one of these days we'll do
a test series with other biomass sources. I've tried chips and they seem to
work well.

Dean

On Mon, May 25, 2015 at 3:55 PM, alex english <aenglish444 at gmail.com> wrote:

> Dean,
> Thanks for the data. Have you any data using "real' wood chips in the Tom
> R patterned stove? I know Tom would use both fuels in his. A power factor
> should be included. There are folks working on producing premium chips for
> smaller furnaces. I don't think the TLUD 'authorities' have spec'd the
> perfect chip or range of acceptible chips, for size, species and moisture
> to maintain an even active descending front.
>
> Alex
>
> On Mon, May 25, 2015 at 11:12 AM, Dean Still <deankstill at gmail.com> wrote:
>
>> 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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