[Stoves] Torrifaction topics Re: Pellet stoves - risks

Paul Anderson psanders at ilstu.edu
Wed Sep 9 20:36:24 CDT 2015


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 <mailto:franke at cruzio.com>
>
>
>
>
>> On Sep 9, 2015, at 9:23 AM, alex english <aenglish444 at gmail.com 
>> <mailto: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 
>> <mailto: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 <mailto:franke at cruzio.com>
>>
>>
>>
>>
>>>     On Sep 9, 2015, at 8:20 AM, Paul Anderson <psanders at ilstu.edu
>>>     <mailto: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 <mailto:psanders at ilstu.edu>    
>>>     Skype: paultlud      Phone:+1-309-452-7072 <tel:%2B1-309-452-7072>
>>>     Website:www.drtlud.com <http://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 <mailto:franke at cruzio.com>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>     On Sep 6, 2015, at 5:32 AM, Paul Anderson <psanders at ilstu.edu
>>>>>>     <mailto: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 <mailto:psanders at ilstu.edu>    
>>>>>>     Skype: paultlud      Phone:+1-309-452-7072 <tel:%2B1-309-452-7072>
>>>>>>     Website:www.drtlud.com <http://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 <mailto:franke at cruzio.com>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>     On Sep 3, 2015, at 12:28 PM, Dean Still
>>>>>>>>     <deankstill at gmail.com <mailto: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 <mailto: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
>>>>>>>>         <mailto: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
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>         _______________________________________________
>>>>>>>>>         Stoves mailing list
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>>>>>>>>>
>>>>>>>>>         for more Biomass Cooking Stoves,  News and Information
>>>>>>>>>         see our web site:
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>>>>>>>>
>>>>>>>>         _______________________________________________
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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 <tel:%28541%29%20767-0287>
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