[Stoves] black sheet corrosion retort kiln bottom plate / kensmetal

Mon Sep 23 07:51:09 CDT 2019

Chris,

I've used Apex Steel (https://www.apex-steel.com/) in Nairobi.  I cannot
vouch for their metals but they are responsive.

Thank you,
Kevin

*Kevin McLean, President*
*Sun24*

*https://sun24.solar <https://sun24.solar>  Sun24 Cookstoves Overview
<https://docs.google.com/document/d/1ZryS7gQ1q3zKLZPM2KcXdtIHbOYQp4PbloPqMvrlZ5Y/edit?usp=sharing>*
*Tampa, Florida, USA*
*+1 (813) 505-3340*

On Mon, Sep 23, 2019 at 8:39 AM Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Chris
>
> I suspect the problem lies in the wood heated and the liquids produced.
>
> The steel is probably made in India. Most steel available in Kenya is made
> in India and is Imperial in all dimensions.
>
> It is also typical for material shipped to Africa to be all the out of
> spec for dimensions, out of limits for content, and out of spec for finish.
>
> It is likely the sulphur content of the sheets is high. If you can't find
> the low chrome stainless, ask for Corten Plate which should have 0.24 %
> carbon content. It might last a little longer.
>
> You could also try painting the hottest part of the sheet with 700 degree
> black paint. It is unlikely that temp will be reached.  If the root problem
> is liquid or gas, not sheet content, it could help.
>
> But the problem will only be "resolved" using a better material. Look
> closely - will the replacement of 1/3 or 1/2 the sheet, the hottest part,
> be sufficient?
>
> Just for good measure, SS316 and SS308 etc are not suitable for high
> temperature applications in stoves. Those are for food and purity
> applications.  Stoves frequently assume that "better" is more expensive.
> Look at the temperature performance chart to check the operating range.
>
> Regards
>
> Crispin
> *From:* scda2 at ymail.com
> *Sent:* September 23, 2019 7:27 AM
> *To:* stoves at lists.bioenergylists.org; crispinpigott at outlook.com
> *Reply to:* scda2 at ymail.com
> *Cc:* sebastianschlott at web.de
> *Subject:* Re: [Stoves] black sheet corrosion retort kiln bottom plate /
> kensmetal
>
> Dear Crispin,
> 1000 thanks for you advice. Hate to type on my small tablet during travel
> in Maroc, but what can i do.
> Very amazing that MS sheet 3mm in India keeps for about 60 burns, but
> Black sheet in Kenya burn holes after only 4 runs. But there might be some
> unknown facts, as i have never been at both places. A) 3mm might not
> actually 3mm but 2mm in Kenya and what the hell kind of big fire they do
> and they use kind of wood which quality i forgot. And i don't know about
> the time of gasification burning wood gas in India, neither in Kenya, (its
> most probably one hour ?).
> Thanks for all your advice on cutting, bending, welding,
> fortunately the retort -kiln design is done in such a way, that no
> cutting, welding bending is necessary, The size of the bottom plate about
> 8"x4" determins the size of the wood chamber.
> I contacted Kensmetal for advice advice, they have a good home page,
> but (of corse) no answer yet from their technical department....
> http://www.kensmetal.co.ke
> <https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.kensmetal.co.ke&data=02%7C01%7C%7C1292eb97bcad4eaeb86608d740190175%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637048348456159819&sdata=yqVaB3yOdHQWs2uGLfaVMxikj055U3YBS0unf20ppPo%3D&reserved=0>
> I will keep u updated
> Best
> Chris ADAM
>
>
> On Thursday, 19 September 2019, 22:01:45 CEST, Crispin Pemberton-Pigott <
> crispinpigott at outlook.com> wrote:
>
>
> Dear Chris
>
> I suggest you consider trying * SS 409* which is typically about 1.5
> times the price of mild steel. It can be thinner so if 3mm MS was working
> in terms of strength, 2mm SS 409 will work as well. It is much stronger.
> The patent has expired so it is available from multiple sources.
>
> Being an SS, the heat transfer rate will be lower, something close to ½
> that of MS. Being thinner will compensate for some of that. Assume you will
> lose 1/3 of the heat transferred from the fire under the end of the
> chamber, so it will take a larger external fire to get the same pyrolysing
> effect in side.   It has an operating temperature of more than 700 C which
> really suits your application.   It will go brown when heated, unlike high
> chrome stainless steel.  I suggest getting *hot-rolled sheets*, not
> cold-rolled because of the albedo of the CR.
>
> This material (also known a*s 3CR12*) is difficult to cut with an angle
> grinder and cutting disk, when thick. I suggest you have it guillotined
> instead. It is very abrasion resistant. If you are forced to cut it with a
> grinder, don’t let it get red hot. Cut by moving the disk contact point
> back and forth on the cut-line.  Using a thinner disk will help (a bit).
> If it gets red hot it will harden considerably and it is already abrasion
> resistant.
>
> It cuts quite well with a saw but make sure there is adequate pressure to
> get the teeth well into the material.  In general stainless has to have a
> deep tool penetration or the surface hardens.
>
> If you are not sure what the material offered is, look for a small % of
> *titanium*, about 1/3 to 1/2 of a %.  It is a low chrome (12%),
> titanium-stabilised stainless steel.
>
> It can be bend in a press brake but it will not bend back.  The elongation
> is about 16% (only) so plan for a larger than normal radius such as 2T or
> 2.5T instead of 1.5. You can weld it with any stainless steel arc rod, all
> of which are made from better material.  The area around the weld will
> harden considerably.  It spot-welds very well.
>
> If you punch holes it will need close to 75% of the depth sheared, higher
> than a standard MS of 33%.  This provides a very smooth hole wall but at
> the expense of a much higher than normal pressure requirement per mm2 cut
>  Increasing the die hole clearance from 1/10thT to 1/6th or 1/5thT will
> probably reduce the punching force needed, if you don’t mind the bottom
> burr.
>
> It will laser cut well, but is a bit messy plasma cutting.  The edge will
> need to be cleaned with a grinder, and the cut edge will be hard.  Nigel PP
> warns that above some temperature the chrome atoms will let go of the
> oxidation sites and condense into droplets within the material. After that
> there is going to be some irreversible corrosion, though I think you will
> be so happy you won’t care.
>
> This material is available down to 0.3mm which is used in a double layer
> for catalytic converter housings.
>
>
>
> You can buy hot-rolled sections like angle iron made of the same material.
>
>
>
> Good luck with the demonstration.  You might want to use it in another
> thickness on top as well.
>
>
>
> Regards
>
> Crispin
>
> *From:* Stoves <stoves-bounces at lists.bioenergylists.org> *On Behalf Of *
> dr.adam
> *Sent:* Wednesday, September 18, 2019 2:53 AM
> *To:* Discussion of biomass cooking stoves <
> stoves at lists.bioenergylists.org>
> *Subject:* Re: [Stoves] black sheet corrosion retort kiln bottom plate
>
>
>
> Dear Teddy
>
> HELP !
>
> You might be familiar with metal sheet dealers in Nairobi?
>
> Near Mombasa/ Kilifi  the company komaza.com (new face of forestry) built
> one of my retort-kilns.
>
> I guess they used poor quality black sheet 8"x4", 3mm for the bottom plate
> and they complained that already after 4 batches operation they had these
> horrible holes near the fire chamber.
>
>
>
> You have any idea which kind of more heat resistant metal plates (boiler
> sheet?) might be available in Kenya, any name of a dealer? Kenya with its
> tea producing industry and use of steam boilers, should have such sheets
> available?
>
> Thanks in advance.
>
> We might see us on 5th Nov. in Nairobi Conference  :-)
>
> Chris ADAM
>
>
>
> [image: Inline image]
>
> I have even doubt they used a 3mm sheet (they paid 7500KSH for it)?
>
>
>
>
>
> On Monday, 16 September 2019, 13:03:33 CEST, Cookswell Jikos <
> cookswelljikos at gmail.com> wrote:
>
>
>
>
>
> A very interesting short video on a very clever company that's started up
> in Kenya
>
>
>
> https://www.youtube.com/watch?v=EaJNe0im-eM
> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DEaJNe0im-eM&data=02%7C01%7C%7C1292eb97bcad4eaeb86608d740190175%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637048348456159819&sdata=MtrNzOHTyWXomCLBp4rMeEfBzGESFGxa%2FcpuZ%2FAPqs8%3D&reserved=0>
>
>
>
>
>
>
> Any suggestions for better sawdust burning stoves sub 10$ that could be
> locally made?
>
>
>
> Best,
>
>
> Teddy
>
>
>
>
> _______________________________________________
> 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/
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20190923/04b3f48f/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 140289 bytes
Desc: not available
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20190923/04b3f48f/attachment.jpg>