[Stoves] Torrifaction topics Re: Pellet stoves - risks
Dean Still
deankstill at gmail.com
Thu Sep 10 10:18:34 CDT 2015
Hi Paul,
We purchased torrified pellets and burned them in the natural draft TLUDs
here.
The pellets still make flame but there is less PM 2.5.
We will get back to testing now that Festival season is coming to a close.
Best,
Dean
On Wed, Sep 9, 2015 at 9:08 PM, Paul Anderson <psanders at ilstu.edu> wrote:
> Frank, see below. (JSS for web)
>
> Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
> Email: psanders at ilstu.edu
> Skype: paultlud Phone: +1-309-452-7072
> Website: www.drtlud.com
>
> On 9/9/2015 9:56 PM, Frank Shields wrote:
>
> Thanks Paul for the comments,
>
> So you find the typical pellets suitable for your TLUD? and they operate
> at optimum as compared to other mostly non-uniform types biomass?
> This i find interesting. Thanks.
>
> Nothing is "optimum", but pellets come close. Other biomass can be quite
> uniform, such as natural quarters or thirds of nut shells, or even segments
> of maize cobs. And "too uniform" are the sawed pieces of wood that were
> the "standard fuel" of testing for many years (and somewhat still is) at
> Aprovecho because the flat surfaces would pack together and essentially
> become 2 or 3 times "thicker". The greater factors are dryness (MC) and
> being too large, causing bridging with big air spaces.
>
>
> When you talk of control over the primary air are you suggesting a fan?
>
> No. I was referring to natural draft.
>
> If not I would think the conditions of air flow is: 1) diameter of
> combustion chamber 2) height of combustion chamber 3) percent air volume in
> the bulk fuel 4) shape of the air voids in the bulk fuel 5) temperature of
> the combustion 6) evenness of the flame front and 7) insulation of the
> combustion chamber. Can’t think of anything else but that is quite a few
> variables. A fan would eliminate all these variables.
>
> Even a fan cannot overcome these variables if it cannot truly virtually
> cut off the air flow.
>
> I was referring to a sliding door to block the air. And it surprising
> how VERY LITTLE primary air can prevent control of a TLUD. Leaks the
> diameter of a pin can prevent control. That was the downfall of the Quad
> TLUD because the air slipped in past the tabs in the slots. So the Troika
> was designed with better sealing of the bottom (and with one less leg and
> design factors, but air leakage was the Quad problem.)
>
>
> With the GEK from All Powers Lab you could pipe the gases 30 feet where
> they are cool to the touch and the flame is a nice blue color with no
> smoke. Do you think it possible to achieve these conditions in your TLUD as
> the set-up are about the same. But the flame front and char above needs to
> be HOT.
>
> No. GEK is a true downdraft, with the hot pyrolytic gases passing
> downward through the red-hot char bed, cracking the long molecules. TLUDs
> release the pyrolytic gases upward.
>
>
> The cool gases passing through the char zone and making it past the
> secondary are the gases Dean is talking about that with research might be
> removed from the fuel before using via torrification. This would be a very
> interesting research project.
>
> I disagree. The gases removed by torrification are what the TLUD needs
> to burn to give the cooking flame. And you will never get all of them
> released even as the material goes to higher temperatures, even when the
> biomass has become char-400 and then char-550 and char-800 degrees C and
> everything in between and beyond. As Crispin and I and others point out,
> there are no "dirty fuels", just inadequate devices for their combustion.
> Biomass cannot be cleaned up for use in a TLUD to do what a TLUD is not
> intended to do, which is to burn the pyrolytic gases. Funding that
> research would take money away for viable research topics. Trying to make
> a TLUD into a generator of gases for internal combustion engines is like
> training cows to run in the Kentucky Derby, because you can train them,
> but they have no chance of winning that race. But if you want milk,
> choose a cow, not a horse. :-)
>
> Paul
>
>
> thanks
>
>
>
> Frank Shields
> franke at cruzio.com
>
>
>
>
> On Sep 9, 2015, at 6:36 PM, Paul Anderson < <psanders at ilstu.edu>
> psanders at ilstu.edu> wrote:
>
> Frank and Alex,
>
> About the conditions of the fuel and above the fuel, we can also add the
> conditions in the bed of char that is above the MPF. And the main factor
> that I am thinking of is the temperature in those zones above the MPF.
> Imagine that the gases become rather cool before reaching the incoming
> secondary air, then there could be greater likelihood that some could slip
> past the secondary burning.
>
> Frank asked about the preferred fuel sizes in my (or other) TLUDs. I do
> not have such preferences. I like pellets, of course. But there must be
> allowance for a variety of sizes.
>
> NOTE: I advocate some form of control on the entry of the primary air
> that then can move upward. TLUD stoves that rely on the sizes of the air
> passageways in the fuels as the control mechanism are seriously restricted
> to a specific size and shape of fuel.
>
> Paul
>
> Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
> Email: psanders at ilstu.edu
> Skype: paultlud Phone: +1-309-452-7072
> Website: www.drtlud.com
>
> On 9/9/2015 11:42 AM, Frank Shields wrote:
>
> Dear Alex,
>
> I think the fuel and the environment above the fuel is both of equal
> importance. So do we change the fuel or the combustion set-up? that is the
> question.
>
> A stove system that is able to burn a wide variety of fuels and widely
> sold may be difficult and/or expensive to make adjustments for a specific
> fuel. So in this case if it is easy to change the fuel that may be
> preferred. I think the answer to change the fuel or the stove system
> depends on the amount of work and expense involved.
>
> Thats the way I look at it today. : )
>
> Regards
>
> Frank
>
>
>
>
> Frank Shields
> franke at cruzio.com
>
>
>
>
> On Sep 9, 2015, at 9:23 AM, alex english <aenglish444 at gmail.com> wrote:
>
> Frank,
> If there are emissions that derive from fuel directly and then escape
> further 'processing' by flame environments by sneaking by , then they might
> be called something like primary fuel derived emissions. PFDEs. It is safe
> to say, I think,that most of these would be transformed into products of
> complete or incomplete combustion in and around the flame. I may be
> confused, but this mix would likely have less to do with the fuel than the
> environment above fuel.
> Hmm
> Alex
> On 2015-09-09 8:55 AM, "Frank Shields" < <franke at cruzio.com>
> franke at cruzio.com> wrote:
>
>> Dear Paul and Stovers,
>>
>> For ‘user-acceptance’ and ‘market driven’ I would think preparing the
>> fuel optimized for your stove that quickly boils water with little dirty
>> emissions is one and the same.
>>
>> I would think that would be drying and, perhaps as Dean has mentioned,
>> driving off some of the early volatiles that may pass the secondary before
>> complete combustion.
>>
>> Paul - Do you have information as to the optimum size and shape the
>> biomass should be for your stove? That should be determined.
>> Then we go to testing the parameters of the biomass like carbon bulk
>> density and carbon particle density along with water soluble sugars and
>> lipids that may contribute to poor emissions. It could be as simple as
>> soaking and draining out constituents to improve the quality as well as
>> heating to drive off the early volatiles.
>>
>> But first we need to find what it is in the fuel that causes the poor
>> emissions. That could be to take some problem biomass and get a baseline
>> from testing.
>> Then pre-heat to drive off early volatiles and re-test. Then using
>> another batch soak in hot water, drain, dry and re-test. And finally soak
>> in a solvent, drain, dry and re-test.
>>
>> Using emissions tests to get ratios of emission components and particles
>> might be enough to determine success. Or add helium surrogate to get
>> absolute concentrations as they are produced might be info that would help.
>>
>> Regards
>>
>> Frank
>>
>>
>>
>> Frank Shields
>> <franke at cruzio.com>franke at cruzio.com
>>
>>
>>
>>
>> On Sep 9, 2015, at 8:20 AM, Paul Anderson < <psanders at ilstu.edu>
>> psanders at ilstu.edu> wrote:
>>
>> Frank and Stovers,
>>
>> My simplistic interest in the "induced drying" of biomass fuels is
>> related to improving the user-acceptance of the TLUD cookstoves and the
>> establishment of some fuel marketing chain. The degree of drying /
>> torrification would be market driven, not related to emissions or technical
>> characteristics of the resultant fuels.
>>
>> As the degree of drying / heating of the fuels increases, the cost of
>> that processing will rise. So I favor the minimum treatment that will
>> benefit the customer and will justify the increase in fuel price.
>>
>> A favorable situation would be to use essentially waste heat to prepare
>> the future fuel supplies. Or expend a small amount of fuel to prepare a
>> much larger amount of fuel that will be sold with sustainable profitability.
>>
>> Paul
>>
>> Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
>> Email: psanders at ilstu.edu
>> Skype: paultlud Phone: +1-309-452-7072
>> Website: www.drtlud.com
>>
>>
>> On 9/8/2015 3:55 PM, Frank Shields wrote:
>>
>> Dear Paul,
>>
>> Making batches of different degrees of torrification biofuels is one
>> thing and then testing and interpreting the results is another.
>> Do we measure success on emissions or time it takes to boil water? And
>> them we have other variables like bulk carbon density and particle carbon
>> density. Volatiles and adding moisture. Size and shape will be important.
>>
>> So once we figure out a way of making constant quality material for
>> testing there is still a lot of research work to do. Agreeing on what we
>> use as a measure of success is the first.
>>
>> regards
>>
>> Frank
>>
>>
>>
>> Frank Shields
>> <franke at cruzio.com>franke at cruzio.com
>>
>>
>>
>>
>> On Sep 6, 2015, at 5:32 AM, Paul Anderson < <psanders at ilstu.edu>
>> psanders at ilstu.edu> wrote:
>>
>> Dear all,
>>
>> While agreeing with Frank and Dean, I suggest that there are sufficient
>> "degrees of torrification" that we should subdivide the discussion.
>>
>> 1. Wet or green wood High moisture content (MC)
>> 2. Dried in 20% MC range
>> 3. Dried to 10% MC or less
>> 4. Kiln dried (heated to ???? degrees C)
>> 5. Super dried (heated to maybe 120 C)
>> 6. Toasted (slightly browning) 120 to 180 C ???
>> 7. Early torrified 180 - 240 C ??
>> 8. Fully torrified 240 - 300 C ??
>> 9. Undergoing pyrolysis above 300 C ???
>> 10. And then we have different "chars" based on temperatures during
>> production, 400 C, 450 C, 550 C, 700 C, 900 C
>>
>> LOTS of question marks there. Frank and others can refine this much
>> better. Issues of MC and temperatures and "names" (and related to
>> sufficient time to have the heat impact reach the center of the pieces of
>> biomass, not just flash heating), and probably more variables.
>>
>> To just say "torrified" leaves too many uncertainties and possible
>> mis-understandings / assumptions by the large number of readers in
>> different cultures and with different experiences.
>>
>> I can say that TLUD stoves (when properly made and with consistent MC in
>> the fuels) work very well with the 3, 4, 5, and 6 (above) fuels. They do
>> not like much moisture content, and they do not want the fuel to be already
>> partially charred.
>>
>> Reasonable quality fuel supply is so important for TLUD acceptance.
>> More work could be done about this.
>>
>> Paul
>>
>> Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
>> Email: psanders at ilstu.edu
>> Skype: paultlud Phone: +1-309-452-7072
>> Website: www.drtlud.com
>>
>> On 9/5/2015 11:45 PM, Frank Shields wrote:
>>
>> Dear Dean, Stovers,
>>
>> I have not worked with stoves but working with all types of pellets
>> (paper, manures, etc.) and good quality wood pellets I find they burn in
>> pipes very poorly and seem they are really just good for pellet stoves
>> dropping in one at a time.
>> I think you may be on to something in regards to torrifying to some
>> extent before using to get a cleaner combustion. I see the real challenge
>> is quality control because torrification takes place in a very narrow range
>> and it is so easy to have a ‘run-a-way’ combustion that heats higher than
>> the setting you want. I was able to achieve that in my pipes but only after
>> much practice and s l o w l y raising the temperature to desired
>> amount. Not sure how this would be done commercially. It would be a very
>> interesting project.
>>
>> We also may be able to get clean combustion by finding constituents in
>> the pellets (and all biomass for that matter) that create these large
>> organic volatile structures that give problems and eliminate them from the
>> fuel.
>>
>> Regards
>>
>>
>> Frank
>>
>>
>>
>>
>>
>>
>> Frank Shields
>> <franke at cruzio.com>franke at cruzio.com
>>
>>
>>
>>
>> On Sep 3, 2015, at 12:28 PM, Dean Still < <deankstill at gmail.com>
>> deankstill at gmail.com> wrote:
>>
>> Hi Frank,
>>
>> After limited experience in Uganda and China my experience is that it's
>> not easy to make clean burning recipes for biomass pellets.
>>
>> Seems like the torrified pellets emit less PM but we need to do more
>> tests.
>>
>> Best,
>>
>> Dean
>>
>> On Thu, Sep 3, 2015 at 8:44 AM, Frank Shields < <franke at cruzio.com>
>> franke at cruzio.com> wrote:
>>
>>> Dear Chispin and stovers
>>>
>>>
>>> Of course no mention of the quality of the pellets! In the U.S. The go
>>> through standard testing and results labeled
>>> On bags. But pellets are made of all sorts of materials and energy
>>> values and volatile profiles. It would seem this would be part of the
>>> discussion.
>>> Thanks
>>> Frank
>>>
>>> Sent from my iPhone
>>>
>>> On Sep 3, 2015, at 6:13 AM, Crispin Pemberton-Pigott <
>>> <crispinpigott at outlook.com>crispinpigott at outlook.com> wrote:
>>>
>>> Dear Friends
>>>
>>>
>>> There is a broad move around the world to create pelleted fuel from
>>> biomass and burn it in tighter spaces. This report was noted in the
>>> Alliance for Green Heat newsletter:
>>>
>>>
>>> *Updated on the Mt. Vernon pellet stove recall*
>>> <http://r20.rs6.net/tn.jsp?f=001d7dcszljjgfEKYA31aaHyRsMRRejQSaDUDJHpy5B3lPW1W0QcteHERbDFukIhEc2-_1cKtvym49J_ai7zvt1WWN26UenG3N6joIskOVraQhcc__S5dpEwVlcw8pbpwWuwRufyvZSstnraBJTXAbr2wOPL-tX7Wypj3swduscC5I1Staun8b2olWMeGwuEsLEKsSA0qsYd2J1B5b7fDXOH7vLn_jPI3y12xty5nULquL9LCJu6LE7P-Ysu5qiL45LFwfyKNL4feu5XOzEawUh0a7X5VAZM8fb7F4K1l1kHGeFIFftvkxNTEEi9J_I05V6LKmiIZSk4GOQXJRAMRf5NDba52L-Wn_9jVkbpqju9Kifq8bMZm_xowV5Qn2NerYbUfu00_a4isbrvL9gktLkSQ==&c=WnPhxOQ3V-ic1ZJ3NBDpcipfRPq-UdIrBKPYwMfkxe-_CRS45fkQ4w==&ch=gnDbpciWOWhz6yV0o8Zdcoli15r_rpgR21xk0iBJKKi_KYRnwLVmTw==>
>>>
>>> Last month, we reported on the recall of 2,000 Mt. Vernon E2 pellet
>>> stoves after about 6 experienced explosions that shattered the glass in the
>>> front door. No injuries have been reported. The Alliance wrote to HHT
>>> asking for clarifications about what caused the malfunction and whether the
>>> stove would be 3rd party tested again for safety. *Click here*
>>> <http://r20.rs6.net/tn.jsp?f=001d7dcszljjgfEKYA31aaHyRsMRRejQSaDUDJHpy5B3lPW1W0QcteHEfKhE4oT8BuuAHDwJ1L0g7GrKo5I0xEbbDvkpCt65Xds638GUTKpc9WxdvAozGBIprVOl7vL1wQKB10dTQFUofpAQnr3z9i2zwxCfiQA3rCg4PVvKxSMWgMWDhYiC_fJ7rGJlBpUwsdpb9A-KCa9c_WZg3sRbG1GpSOEsBvotEVw3FLKELU68l1aktAt4KqIrr-AbESuj8iSP6u9wdRQU3L5aMshSI5ocFejIUjrSB94PP9Q2h_zrmWcq3brFPbj1VqWZSiFfmDp50WpCw2b2SOvJ-9NqzbOgn8sgdzIHO2tNWqczgkuFI6d7bzwPt4D_g==&c=WnPhxOQ3V-ic1ZJ3NBDpcipfRPq-UdIrBKPYwMfkxe-_CRS45fkQ4w==&ch=gnDbpciWOWhz6yV0o8Zdcoli15r_rpgR21xk0iBJKKi_KYRnwLVmTw==>
>>> for a copy of the HHT response.
>>>
>>>
>>> The drive to create better combustion often means having a staged
>>> gasification-then-burning type of design. That may be a source of problems.
>>>
>>>
>>> I know of at least one instance of a very modern TLUD coal stove
>>> explosion in Ulaanbaatar when the operator refuelled it with a significant
>>> amount of lignite (high volatiles) while it was already very hot. This
>>> generated a huge amount of combustible gas while simultaneously
>>> extinguishing the gas flame. Eventually it heated up to the point that the
>>> gas ignited and it blew flaming fuel out of the top of the stove, around
>>> the room. A public education campaign tried to prevent exactly this sort
>>> of mis-operation.
>>>
>>>
>>> Regards
>>>
>>> Crispin
>>>
>>>
>>> _______________________________________________
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>>
>>
>> --
>> Dean Still
>> Executive Director
>> Aprovecho Research Center
>> PO Box 1175
>> 76132 Blue Mountain School Road
>> Cottage Grove, OR 97424
>> (541) 767-0287
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Executive Director
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PO Box 1175
76132 Blue Mountain School Road
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(541) 767-0287
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