[Stoves] Clinker Formation

Sat May 17 00:50:38 CDT 2014

Yes we did and we got .03% Sulphur and .014 %

Regards
Shailendra

On Sat, May 17, 2014 at 11:11 AM, Tom Miles <tmiles at trmiles.com> wrote:

> The Dolomites would be best. The china clay depends on the composition of
> the bagasse. Have you have the bagasse ash, sulfur and chlorine tested?
>
>
>
> Tom
>
>
>
> *From:* Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On
> Behalf Of *Shailendra Garg
> *Sent:* Friday, May 16, 2014 10:34 PM
>
> *To:* Discussion of biomass cooking stoves
> *Subject:* Re: [Stoves] Clinker Formation
>
>
>
> Also what should be the composition and grade of the china clay to be used.
>
>
>
> Chemical Analysis of China Clay Powder:
>
> Al2o3
>
> 30 � 38 %
>
> Sio2
>
> 40 � 45 %
>
> LOI
>
> 10 - 13 %
>
>
>
> Is the above an okay composition?
>
> Also they say that the China Clay powder is available from 100 Mesh To
> 500 Mesh.
>
> For Dolomite I can see
>
>
>
> Contant
>
> Percentage
>
> MgO
>
> 50-58%
>
> CaO
>
> 30-37%
>
> SiO
>
> 2-2.50%
>
> R2O3
>
> 5-8%
>
>
>
> Is the above composition the right composition?
>
>
>
> Regards
>
> Shailendra
>
>
>
> On Sat, May 17, 2014 at 10:56 AM, Shailendra Garg <
> shailendra.garg at pelletenergysystems.com> wrote:
>
> Thanks a lot Tom/Crispin/Jonathan.
>
>
>
> Tom, did you use Dolomite or Kaolini Clay at some point? I am wondering
> how much % of these should be used. Also are there other natural agro waste
> which we can probably mix with bagasse to get the same result (high
> potassium I mean).
>
>
>
> Regards
>
> Shailendra
>
> ---------- Forwarded message ----------
> From: *Tom Miles* <tmiles at trmiles.com>
>
> Date: Fri, May 16, 2014 at 8:29 PM
> Subject: Re: [Stoves] Clinker Formation
>
> To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
>
> Shailendra,
>
>
>
> The composition of bagasse varies  considerable. We have gasified and
> burned very clean bagasse and very dirty bagasse. The larges variation
> comes when the cane tops and leaves, called “trash”, are included with the
> cane as it goes through the mill. The tops and leaves contain high
> concentrations of sodium, potassium, sulfur, and chlorine and low
> concentrations of silica, calcium, and magnesium. The balances of these
> minerals determine the melting temperatures of the ash mix and whether
> particles stick together as agglomerates or melt and fuse like glass. The
> plant takes up salts from alkaline soils which is not always cleaned in the
> sugar extraction process. This increases the concentrations of low melting
> compounds of chlorine (KCL, NaCl) and sulfur. Straw and other agricultural
> residues that contain annual growth have very high levels of potassium. The
> proportion of potassium to silica determines if the silica will become
> sticky or melt. The more potassium, the lower the melting temperature.
>
>
>
> Melting temperature measured I the lab are usually not accurate because
> they use methods appropriate for coal in preparing the samples to be
> tested, not biomass. For coal the fuel sample is ashed at 850C or 900C.
> That vaporizes elements that are important to melting. In Europe and North
> American labs the fuel sample is prepared at 550C or 600C which is below
> the vaporization temperatures. Then when the ash is heated it will melt at
> more typical temperatures.
>
>
>
> Pellets are dry so they burn at very high temperatures ( 800-1000 C). To
> prevent slagging you need to burn the fuel in stages. The first stage
> includes drying, de-volatilization,, pyrolysis (heating) and gasification
> (partial oxidation). You must control the air at that stage on the grate so
> that temperatures do not exceed 750 C. This is usually done by limiting air
> through the fuel pile. When the gases emerge above the fuel pile you can
> add air and increase the temperature, usually to 800-900C. Then you must
> have a mechanism for removing the dry ash. If it remains exposed to the hot
> flame it can stick together (sinter) or melt ()fuse) to ash.
>
>
>
> Stages combustion in a pellet burner can be a challenge. Most pellet
> burners are designed to burn the fuel and air mixture at the highest
> temperature which is usually in the range of 1000C- 1100C range which will
> melt most dirty fuels.
>
>
>
> Another approach is to add minerals to the fuel ,like dolomite or kaolin
> clays, that contain high proportions of calcium or magnesium. These
> minerals will raise the melting temperature of the mixture and reduce
> sintering or slagging.
>
>
>
> Tom Miles
>
>
>
> *From:* Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On
> Behalf Of *Crispin Pemberton-Pigott
> *Sent:* Friday, May 16, 2014 4:36 AM
> *To:* stoves at lists.bioenergylists.org
> *Subject:* Re: [Stoves] Clinker Formation
>
>
>
> Dear Shailendra
>
>
>
> What you describe is what happens when there is a flux present - probably
> more than one. A flux reduces the melting temperature and it is not a
> surprise that you have a clinker problem. It may well be glass, not ash in
> the mineral sense but of course glass is a mineral.
>
>
>
> Perhaps Alex English will comment because he has made more glass
> accidentally than most of us put together.
>
>
>
> Roger Samson showed us that leaving switchgrass outside through the winter
> removed Cl and K by leaching. The problem went away.
>
>
>
> Another possibility is to change the combustion to try and prevent the
> temperature ‎rising so high. That would involve cooling the char burning
> zone by not preheating the primary air, just as an example.
>
>
>
> Regards
>
> Crispin
>
>
>
>
>
>
>
> BBM 2B567C3
>
> ‎
>
> Dear All,
>
>
>
> We in India are trying to find a solution to the clinker problem in the
> stoves as the temperature reaches above 1000 degrees very soon in a 30KW
> stove for example. Now the pellets we are using are mainly bagasse based,
> and its ash melting point is above 1000 degrees but still it is not giving
> the right result. The pellets are not made of 100% bagasse and the size we
> are using is 8mm.
>
>
>
> Please give your inputs/suggestions if this problem can be solved by
> adjusting the primary secondary air or we need to change the composition of
> the pellets.
>
>
>
> Regards
>
> Shailendra
>
>
>
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