[Stoves] Stoves Digest, Vol 62, Issue 18

Chikere Okorafor chikereokorafor at gmail.com
Fri Oct 16 22:20:05 MDT 2015


Thank you,
will work on that and provide feedback.

On 10/14/15, stoves-request at lists.bioenergylists.org
<stoves-request at lists.bioenergylists.org> wrote:
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> Today's Topics:
>
>    1. Re: Stoves Digest, Vol 62, Issue 17 (Chikere Okorafor)
>    2. Fuels and combustion analysis (Frank Shields)
>    3. Re: TLUD pellets stove with a venturi burner. Pictures of	a
>       cooking cycle. (Roberto Poehlmann)
>    4. Re: TLUD pellets stove with a venturi burner. Pictures	of	a
>       cooking cycle. (Crispin Pemberton-Pigott)
>    5. Re: TLUD pellets stove with a venturi burner. Pictures of a
>       cooking cycle. (alex english)
>    6. TLUD pellets stove with a venturi burner. Pictures of a
>       cooking cycle. (Julien Winter)
>    7. TLUD pellets stove with a venturi burner. Pictures of a
>       cooking cycle. (Roberto Poehlmann)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 13 Oct 2015 19:42:03 +0100
> From: Chikere Okorafor <chikereokorafor at gmail.com>
> To: stoves at lists.bioenergylists.org
> Subject: Re: [Stoves] Stoves Digest, Vol 62, Issue 17
> Message-ID:
> 	<CAJ3_gsyfT6NBRGrVCtnEKkrb0L9yi2XUGy9zduX-8McAPGYOrA at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> On 10/13/15, stoves-request at lists.bioenergylists.org
> <stoves-request at lists.bioenergylists.org> wrote:
>> Send Stoves mailing list submissions to
>> 	stoves at lists.bioenergylists.org
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> 	http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
>>
>> or, via email, send a message with subject or body 'help' to
>> 	stoves-request at lists.bioenergylists.org
>>
>> You can reach the person managing the list at
>> 	stoves-owner at lists.bioenergylists.org
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of Stoves digest..."
>>
>>
>> Today's Topics:
>>
>>    1. Help: What areas can I work on stoves in terms of fuels	and
>>       combustion? (Chikere Okorafor)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Tue, 13 Oct 2015 13:38:06 +0100
>> From: Chikere Okorafor <chikereokorafor at gmail.com>
>> To: stoves at lists.bioenergylists.org
>> Subject: [Stoves] Help: What areas can I work on stoves in terms of
>> 	fuels	and combustion?
>> Message-ID:
>> 	<CAJ3_gsyyK611BK7YeeExqGqsvZOKDW61X9a6BVx0TbLyG+xevA at mail.gmail.com>
>> Content-Type: text/plain; charset=UTF-8
>>
>> Good day House,
>> I am running a Masters programme in Thermofluids and Power Plant
>> option at Federal University of Technology, Minna, Nigeria.
>> I am also working on improving and reducing the production cost of a
>> wood stove (AUTOCAD design attached) but confined to Combustion
>> analysis and fuels used.
>>
>> What areas can I work on in terms of fuels and combustion analysis?
>> Contributions are highly welcome.
>> Thank you
>>
>>
>>
>> ------------------------------
>>
>> Subject: Digest Footer
>>
>> _______________________________________________
>> Stoves mailing list
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>> http://www.bioenergylists.org/
>>
>>
>> ------------------------------
>>
>> End of Stoves Digest, Vol 62, Issue 17
>> **************************************
>>
>
>
> --
> -Chikere Okorafor
> Nigerian Airspace Management Agency
> +2348063923146
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> ------------------------------
>
> Message: 2
> Date: Tue, 13 Oct 2015 13:19:46 -0700
> From: Frank Shields <franke at cruzio.com>
> To: Discussion of biomass cooking stoves
> 	<stoves at lists.bioenergylists.org>
> Subject: [Stoves] Fuels and combustion analysis
> Message-ID: <0D636A86-176A-4504-B466-55F86257976E at cruzio.com>
> Content-Type: text/plain; charset=us-ascii
>
> Dear Chikere,
>
>
> Suggestion:
> You will need a combustion chamber where you can put in oven dried biomass
> where combustion is consistent and repeatable per based on emission reading
> taken from a set-up like sold at Aprovecho.
> You will need small pipes going into the combustion chamber just below the
> secondary where you can add gasses and monitor the effects of these gases
> from reading of the emissions.
> You will need a tank of compressed CO.
> You will need a kiln where long and capped iron pipes are added. The top cap
> fitted with a tube going out of the kiln.
> You will need compressed air.
> You will need tea pot with steam directed out of a tube
>
> Once you fire up the stove and, after several runs, you have a baseline on
> the emissions you then start adding through the stainless tube entering just
> below the secondary the following:
>
> A) CO from the tank
> B) Pyrolysis gases from the biomass in the pipes as the kiln heats to 450
> deg. C.
> C) Air from the compressed air tank
> D) Steam from a boiling water pot
>
> What you want to find out is the range of conditions your combustion chamber
> will take before the emissions are out of range.
> Then, perhaps, what design change can be made per 1) fuel and/or 2) physical
> dimensions for the combustion chamber to be more Robust in accepting greater
> variation of the four (CO, pyrolysis gases, moisture and primary air) and
> still be clean burning.
>
> A lot of variables to organize and control but it seems that is what you are
> good at.
>
>
> Regards
>
> Frank Shields
> 202 Amador
> Watsonville, CA  95076
> (831) 246-0417 cell
> franke at cruzio.com
>
>
>>>
>>> Today's Topics:
>>>
>>>   1. Help: What areas can I work on stoves in terms of fuels	and
>>>      combustion? (Chikere Okorafor)
>>>
>>>
>>> ----------------------------------------------------------------------
>>>
>>> Message: 1
>>> Date: Tue, 13 Oct 2015 13:38:06 +0100
>>> From: Chikere Okorafor <chikereokorafor at gmail.com>
>>> To: stoves at lists.bioenergylists.org
>>> Subject: [Stoves] Help: What areas can I work on stoves in terms of
>>> 	fuels	and combustion?
>>> Message-ID:
>>> 	<CAJ3_gsyyK611BK7YeeExqGqsvZOKDW61X9a6BVx0TbLyG+xevA at mail.gmail.com>
>>> Content-Type: text/plain; charset=UTF-8
>>>
>>> Good day House,
>>> I am running a Masters programme in Thermofluids and Power Plant
>>> option at Federal University of Technology, Minna, Nigeria.
>>> I am also working on improving and reducing the production cost of a
>>> wood stove (AUTOCAD design attached) but confined to Combustion
>>> analysis and fuels used.
>>>
>>> What areas can I work on in terms of fuels and combustion analysis?
>>> Contributions are highly welcome.
>>> Thank you
>>>
>>>
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 13 Oct 2015 21:31:18 -0300
> From: Roberto Poehlmann <roberto.poehlmann at gmail.com>
> To: stoves at lists.bioenergylists.org
> Subject: Re: [Stoves] TLUD pellets stove with a venturi burner.
> 	Pictures of	a cooking cycle.
> Message-ID:
> 	<CAK_QYTwZDhFMUTENtTvzais29Pzq4dRiYZDa5Uc=i-w37JFFwg at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Dear Alex, thanks for your comments. Below some commentaries.
>
> "Roberto,
> I like what you have done. A stable blue flame is interesting. Do you think
> you are getting a bit of premix happening with you lowest secondary holes?
> I have two theories about the colour. One is a combination of premix and
> excess air. The other is that at low turn down, low superficial velocities,
> you get peak bed temperatures down around 500C or even lower at the sides
> of the chamber or maybe even inside the pellet. I think there might be a
> different mix of gasses at these temperatures that make it easier to burn
> without forming soot that turns the flame yellow/orange. Perhaps a lower
> C/H ratio.
> When I add a logs to a bed of coals in my stove, with the primary air shut,
> I see dancing blue flames for quite a while before they turn yellow."
>
> RP> Alex, i have tried to premix the gases before burning it, but without
> much success. With this burner, you see flames emerging from every holes,
> so, i think there is not a premix flame. At the first row of holes, the
> flames forms a plane (completly blue) with vertices starting at every 8
> holes.
>
> About excess air, maybe it is the cause of the blue flame generation, I
> don't know. But, to contradict that, at the first rows of holes, you can
> see blue flames starting at every holes, where there is excess of smoke.
> Maybe, when the flame disappears at the top of the burner, there is an
> exccess air. I cannot determine if i had or not excess air. I only can see
> the flames, smell the gases and put the eyes at the exhaust gases to
> determine if i have or not a good flame.
>
> My next step, as Crispin says once, is to measure the exhaust gases with
> the adequate equipment, to optimize the stove.
>
> Another thing i discover, is that a certain conditions, the flame start at
> the base of the cone and not inside the tube. The reason i thing, is that
> the velocity of the "premix" gases at the tube is greater than the flame
> velocity, and when the premix gases reach the cone, velocity decreases,
> sufficiently to stabilize the flame. I see this phenomenon two or three
> times, and i have no idea how to reproduce it. Maybe is a way to have a
> premix flame.
>
> About the idea of the low superficial velocity, maybe is one of the reasons
> to produce a blue flame, i don't know (again). If you suddently close the
> primary air control at normal operation in a TLUD stove, the flames turns
> more yellow/orange, and if you open the primary air control again after a
> few of seconds, the flames turns completly blue, before it stabilizes
> again. ?Why?
>
> "I had a choked exit on some of my TLUD burners, cone in to secondary air
> and cone out. I called them venturi burners because of the look but I
> abandoned the name because I felt it was all chimney-effect.  I'd like to
> see you have control of the secondary air on the cylinder portion.
>
> If you get a combustion test done, don't be surprised if the best result is
> with a flame with yellow tips.
>
> Nice work.
> Alex"
>
> RP> Thanks Alex. Maybe the mos important factor is the chimney effect as
> you say, and the venturi effect is not as important. What i see is that the
> cone helps to widen the flame. Without the cone, the flames transforms it
> in a tall flame, so the shape of the burner (tube and cone combination)
> helps to maintain the flames near the surface of the cone (venturi effect?,
> sudden expansion effect?).
>
> Here is a link to a series of photos and videos of a cooking cycle executed
> yesterday. Every picture have the time printed in it, to see the evolution
> of the cycle and flames behavior.
>
> https://www.dropbox.com/sh/0ltk3o6pbzanz90/AAAUWrVtNho7ITuBa3eoyR3na?dl=0
>
> I have burned 3 kg of pellet.
>
> At 13:51, i started the fire with the 2 primary air control fully open and
> the 3 secondary air controls fully close.
>
> At 13:59, i closed the primary air controls, and fully open the 3 secondary
> air controls.
>
> At 14:02, i remove the chimney, to lower the gasification rates to see what
> happens.
>
> At 14:04 i put the chimney
>
> At 14 29, i remove the chimney, to lower the power or gasification rates
> again.
>
> At 15:17 i put the chimney again.
>
> At 16:02, i fully open the primary air controls, and close two of the
> secondary air controls
>
> Between 16:03 and 16:08, started the char gasification stage.
>
> At 16:26 , i close more the only open secondary air control.
>
> At 17:06, the flame extinguish
>
> At 17:07 i can ignite again the stove.
>
> At 17:13 the flame extinguish again.
>
> The char and ash left weight 230 grams.
>
> The pyrolisis stage last 2 hours and 10 minutes aprox. The gasification
> stage last 1 hour more aprox., before the first flameout.
>
> If i put a more taller chimney, maybe i can have 30 to 45 minutes more with
> flames.
>
> With this prototype, i am very satisfied with the results, and fullfill my
> requirements of an outdoors cookstove and patio heater with natural draft
> with pellets.
>
> I can see that to lower the power with a chimney, i need to have a more
> sealed primary air control. My goal is to reach the 0,5 kg/hour rates. That
> is, 6 hours with 3 kg of pellets.
>
> Greetings
>
> Roberto Poehlmann
>
> Valdivia, Chile
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> ------------------------------
>
> Message: 4
> Date: Tue, 13 Oct 2015 21:06:31 -0400
> From: Crispin Pemberton-Pigott <crispinpigott at outlook.com>
> To: Stoves <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] TLUD pellets stove with a venturi burner.
> 	Pictures	of	a cooking cycle.
> Message-ID: <COL401-EAS1729A3C374E8EAF9A1F2ED1B13F0 at phx.gbl>
> Content-Type: text/plain; charset="us-ascii"
>
> An HTML attachment was scrubbed...
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>
> ------------------------------
>
> Message: 5
> Date: Tue, 13 Oct 2015 21:29:07 -0400
> From: alex english <aenglish444 at gmail.com>
> To: Discussion of biomass cooking stoves
> 	<stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] TLUD pellets stove with a venturi burner.
> 	Pictures of a cooking cycle.
> Message-ID:
> 	<CA+6hwOov3McqB05aSPKzVZv7W4SUSXQB-Qsm8GJoUKb0VOu=Hw at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Roberto,
> I may have missed this detail, but what is the diameter or area of the fuel
> chamber?
> Alex
>
> On Tue, Oct 13, 2015 at 8:31 PM, Roberto Poehlmann <
> roberto.poehlmann at gmail.com> wrote:
>
>> Dear Alex, thanks for your comments. Below some commentaries.
>>
>> "Roberto,
>> I like what you have done. A stable blue flame is interesting. Do you
>> think you are getting a bit of premix happening with you lowest secondary
>> holes?
>> I have two theories about the colour. One is a combination of premix and
>> excess air. The other is that at low turn down, low superficial
>> velocities,
>> you get peak bed temperatures down around 500C or even lower at the sides
>> of the chamber or maybe even inside the pellet. I think there might be a
>> different mix of gasses at these temperatures that make it easier to burn
>> without forming soot that turns the flame yellow/orange. Perhaps a lower
>> C/H ratio.
>> When I add a logs to a bed of coals in my stove, with the primary air
>> shut, I see dancing blue flames for quite a while before they turn
>> yellow."
>>
>> RP> Alex, i have tried to premix the gases before burning it, but without
>> much success. With this burner, you see flames emerging from every holes,
>> so, i think there is not a premix flame. At the first row of holes, the
>> flames forms a plane (completly blue) with vertices starting at every 8
>> holes.
>>
>> About excess air, maybe it is the cause of the blue flame generation, I
>> don't know. But, to contradict that, at the first rows of holes, you can
>> see blue flames starting at every holes, where there is excess of smoke.
>> Maybe, when the flame disappears at the top of the burner, there is an
>> exccess air. I cannot determine if i had or not excess air. I only can
>> see
>> the flames, smell the gases and put the eyes at the exhaust gases to
>> determine if i have or not a good flame.
>>
>> My next step, as Crispin says once, is to measure the exhaust gases with
>> the adequate equipment, to optimize the stove.
>>
>> Another thing i discover, is that a certain conditions, the flame start
>> at
>> the base of the cone and not inside the tube. The reason i thing, is that
>> the velocity of the "premix" gases at the tube is greater than the flame
>> velocity, and when the premix gases reach the cone, velocity decreases,
>> sufficiently to stabilize the flame. I see this phenomenon two or three
>> times, and i have no idea how to reproduce it. Maybe is a way to have a
>> premix flame.
>>
>> About the idea of the low superficial velocity, maybe is one of the
>> reasons to produce a blue flame, i don't know (again). If you suddently
>> close the primary air control at normal operation in a TLUD stove, the
>> flames turns more yellow/orange, and if you open the primary air control
>> again after a few of seconds, the flames turns completly blue, before it
>> stabilizes again. ?Why?
>>
>> "I had a choked exit on some of my TLUD burners, cone in to secondary air
>> and cone out. I called them venturi burners because of the look but I
>> abandoned the name because I felt it was all chimney-effect.  I'd like to
>> see you have control of the secondary air on the cylinder portion.
>>
>> If you get a combustion test done, don't be surprised if the best result
>> is with a flame with yellow tips.
>>
>> Nice work.
>> Alex"
>>
>> RP> Thanks Alex. Maybe the mos important factor is the chimney effect as
>> you say, and the venturi effect is not as important. What i see is that
>> the
>> cone helps to widen the flame. Without the cone, the flames transforms it
>> in a tall flame, so the shape of the burner (tube and cone combination)
>> helps to maintain the flames near the surface of the cone (venturi
>> effect?,
>> sudden expansion effect?).
>>
>> Here is a link to a series of photos and videos of a cooking cycle
>> executed yesterday. Every picture have the time printed in it, to see the
>> evolution of the cycle and flames behavior.
>>
>> https://www.dropbox.com/sh/0ltk3o6pbzanz90/AAAUWrVtNho7ITuBa3eoyR3na?dl=0
>>
>> I have burned 3 kg of pellet.
>>
>> At 13:51, i started the fire with the 2 primary air control fully open
>> and
>> the 3 secondary air controls fully close.
>>
>> At 13:59, i closed the primary air controls, and fully open the 3
>> secondary air controls.
>>
>> At 14:02, i remove the chimney, to lower the gasification rates to see
>> what happens.
>>
>> At 14:04 i put the chimney
>>
>> At 14 29, i remove the chimney, to lower the power or gasification rates
>> again.
>>
>> At 15:17 i put the chimney again.
>>
>> At 16:02, i fully open the primary air controls, and close two of the
>> secondary air controls
>>
>> Between 16:03 and 16:08, started the char gasification stage.
>>
>> At 16:26 , i close more the only open secondary air control.
>>
>> At 17:06, the flame extinguish
>>
>> At 17:07 i can ignite again the stove.
>>
>> At 17:13 the flame extinguish again.
>>
>> The char and ash left weight 230 grams.
>>
>> The pyrolisis stage last 2 hours and 10 minutes aprox. The gasification
>> stage last 1 hour more aprox., before the first flameout.
>>
>> If i put a more taller chimney, maybe i can have 30 to 45 minutes more
>> with flames.
>>
>> With this prototype, i am very satisfied with the results, and fullfill
>> my
>> requirements of an outdoors cookstove and patio heater with natural draft
>> with pellets.
>>
>> I can see that to lower the power with a chimney, i need to have a more
>> sealed primary air control. My goal is to reach the 0,5 kg/hour rates.
>> That
>> is, 6 hours with 3 kg of pellets.
>>
>> Greetings
>>
>> Roberto Poehlmann
>>
>> Valdivia, Chile
>>
>> _______________________________________________
>> Stoves mailing list
>>
>> to Send a Message to the list, use the email address
>> stoves at lists.bioenergylists.org
>>
>> to UNSUBSCRIBE or Change your List Settings use the web page
>>
>> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
>>
>> for more Biomass Cooking Stoves,  News and Information see our web site:
>> http://stoves.bioenergylists.org/
>>
>>
>>
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> ------------------------------
>
> Message: 6
> Date: Tue, 13 Oct 2015 22:57:49 -0400
> From: Julien Winter <winter.julien at gmail.com>
> To: Discussion of biomass cooking stoves
> 	<stoves at lists.bioenergylists.org>
> Subject: [Stoves] TLUD pellets stove with a venturi burner. Pictures
> 	of a	cooking cycle.
> Message-ID:
> 	<CALv4xTyVC2dmyG3HXA9sfb1MaONMj6Xh9sTcuKy0+KqNx_c-nA at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Roberto;
>
> This is an interesting discussion.  A comment and a question.
>
> Comment: the flame speed of H2 is very fast, so you are likely getting H2
> burning from the lower air holes.  H2 flames are virtually invisible, so
> you will not see them.
>
> A question: do the lower air holes blow the gases and focus heat to the
> centre of the burner?  If so, it is interesting that gases get back out to
> your upper air holes.  Gases will be entrained into the upper level air
> jets, and that could be pulling gases back out the the periphery; along
> with localized bouyancy in the flamelets.  The ca 45? upward angle is
> likely important.
>
> Adjusting the vertical angle of the air jets would be an interesting
> experiment, because I think the angle is critical to the function of your
> burner.
>
> In my experience, pellet fuels have a lower maximum gasification rate than
> some fuels with a more open fuel bed.  If you intend to burn sticks, you
> will have to run some tests on those as well.
>
> Cheers,
> Julien.
>
> --
> Julien Winter
> Cobourg, ON, CANADA
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> ------------------------------
>
> Message: 7
> Date: Wed, 14 Oct 2015 00:45:37 -0300
> From: Roberto Poehlmann <roberto.poehlmann at gmail.com>
> To: stoves at lists.bioenergylists.org
> Subject: [Stoves] TLUD pellets stove with a venturi burner. Pictures
> 	of a	cooking cycle.
> Message-ID:
> 	<CAK_QYTyRvAOf9AwR2rEyW2Btm_wQmUH_dPxXdbu=RHU1JYF5Og at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Alex, the fuel chamber has 16,5 cm of diameter and 22 cm tall.
>
> Roberto P.
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> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
>
>
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://www.bioenergylists.org/
>
>
> ------------------------------
>
> End of Stoves Digest, Vol 62, Issue 18
> **************************************
>


-- 
-Chikere Okorafor
Nigerian Airspace Management Agency
+2348063923146



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