[Stoves] Torrified Pellets
Ronald Hongsermeier
rwhongser at web.de
Mon May 25 11:53:08 CDT 2015
Dear Dean,
It appears that the parameters for the WHO PM2.5 standard is 2mg/min of
_what_ _burning_ _level_ (i.e., we need a wattage parameter of some
type)? When an Italian university study concluded that an average
unfiltered cigarette at human-puffing speed (i.e., smoked in around 5
minutes) produced more particulate than a modern, properly running 250KW
diesel engine fully loaded for an hour, it is important to link those 2
mg with an amount of fuel combusted in that minute, don't you agree?
What is that parameter? Crispin obliquely referred to this earlier along
in this discussion by saying to decrease particulate you just have to go
to a smaller stove. There is a limit for every stove "bore" below which
clean burning (however that's defined) will not be maintainable. And
with airspeed (pressure differential), it's the same thing, there is an
upper limit at which you will have excess air for a given bore.
Well-made charcoal left that particulate somewhere else-- in spades --
probably in the air.
regards,
Ron
P.S. Somehow I seem to be getting a feeling that the WHO standard is not
being chosen for proven health purposes, but rather for certain types of
fuels to be ultimately shown to be by definition "too dirty".
On 25.05.2015 17:12, Dean Still 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
> <mailto: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
> <mailto: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 <mailto: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 <mailto: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
>>> <mailto: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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