[Stoves] Clinker Formation

Sat May 17 00:51:33 CDT 2014

ash is between 5-7%

Regards
Shailendra

On Sat, May 17, 2014 at 11:20 AM, Shailendra Garg <
shailendra.garg at pelletenergysystems.com> wrote:

>
> 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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>>
>>
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