<div dir="ltr">See comments below.<br><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Jun 14, 2013 at 8:50 AM, Kevin <span dir="ltr"><<a href="mailto:kchisholm@ca.inter.net" target="_blank">kchisholm@ca.inter.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><u></u>
<div bgcolor="#ffffff">
<div><font face="Arial">Dear Paul</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">In the TLUD Process, if there was no combustion of char,
then all the phytolythic silica would remain within the char remaining, and
would probably be a minimal health threat. However, the reality is that some of
the char will get fully combusted, releasing the silica as quartz, cristobalite,
or tridamite, depending on the particular local "thermo-metallurgical
conditions." </font></div></div></blockquote><div><br><br></div><div>If channeling occurs in a TLUD, then temperatures rise to the point that cristobalite can form. When channeling occurs, total combustion takes place and the sides of the reactor turn red hot. But before this happens, one begins to see (in my type of TLUD) burner holes that do not support a flame. With a small fan adjustment and shake of the gasifier, the problem is gone.<br>
<br></div><div>Also another nice thing about pellets is that they are not so easily subject to channeling. It is hard to create a channel in the midst of pellets of a high bulk density.<br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#ffffff"><div><font face="Arial">Thus, you may, or may not, have a significant health problem
associated with the biochar produced from RH "Starting Fuel."</font></div></div></blockquote><div><br></div><div>Unlikely, under normal operating conditions within a TLUD gasifier operating on a uniform biomass.<br>
</div><div>But it is highly likely in a direct combustion stove.<br></div><div><br></div><div>So my point is that direct combustion of fine biomass is not ideal. If we gasify or pyrolyze in the context of a top-lit updraft or a bottom-lit downdraft we've got a better device. No CO2 is formed at a big distance from the pot, and the formation of cristobalite is minimized. If we go one step further and use pellets as a fuel, then a lot less particulate matter is emitted.<br>
<br></div><div>The comment that a TLUD gasifier on rice hulls is a one-trick pony leaves me mystified. What does one say about all of the forms of biomass that I have tried in my TLUD other than rice hulls. I cite two prime examples: coffee husks and tobacco stems, both of which are uniform in grain size. And neither of these two products were pelletized.<br>
<br></div><div>But I am convinced that pelleting is the way to go:<br></div><div></div><ul><li>less channeling and therefore less CO2 in the syngas,</li><li>less channeling and therefore less exposure of the reactor wall to truly intense heat,<br>
</li><li>less particulate matter in the syngas,</li><li>a much smaller, lighter and more mobile stove,</li><li>pellets are much easier to transport and store, especially important in an urban setting,</li><li>batch times of as long as 4.5 hours with a reactor height of only 75 cm,</li>
<li>batch times as long as 1.5 hour with a reactor height of only 25 cm,</li><li>it might even be possible to do away with a fan on the shortest version of the pellet gasifier.</li><li>if we shorten the reactor height and do away with a fan, the price of the gasifier drops by more than 50%.</li>
<li>at the same time, this stove will produce biochar in pelleted form, which in Vietnam commands a significant price.</li><li>pelleting makes it possible to use a broad range of fine biomass fuels that would be very difficult to combust.<br>
</li></ul><div><br></div><div></div><div>Thanks.<br></div><div>Paul<br></div><div> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff">
<div><font face="Arial"></font> </div>
<div><font face="Arial">The additives I suggested for your consideration would be
most aggressive toward the "exposed silica" that is most likely to be the
hazard.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">Hope this helps. Any further questions, please let me
know.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">Best wishes,</font></div><span class="HOEnZb"><font color="#888888">
<div><font face="Arial"></font> </div>
<div><font face="Arial">Kevin</font></div>
</font></span><blockquote style="BORDER-LEFT:#000000 2px solid;PADDING-LEFT:5px;PADDING-RIGHT:0px;MARGIN-LEFT:5px;MARGIN-RIGHT:0px"><div class="im">
<div style="FONT:10pt arial">----- Original Message ----- </div>
<div style="FONT:10pt arial;BACKGROUND:#e4e4e4"><b>From:</b>
<a title="paul.olivier@esrla.com" href="mailto:paul.olivier@esrla.com" target="_blank">Paul
Olivier</a> </div>
<div style="FONT:10pt arial"><b>To:</b> <a title="stoves@lists.bioenergylists.org" href="mailto:stoves@lists.bioenergylists.org" target="_blank">Discussion of biomass cooking
stoves</a> </div>
</div><div><div class="h5"><div style="FONT:10pt arial"><b>Sent:</b> Thursday, June 13, 2013 10:28
PM</div>
<div style="FONT:10pt arial"><b>Subject:</b> Re: [Stoves] Burning wet
wood</div>
<div><br></div>
<div dir="ltr">
<div>
<div>
<div>
<div>Kevin,<br><br></div>But why directly combust biomass containing amorphous
silica?<br></div>
<div>Why not use it as fuel in a TLUD where the temperature is well below that
needed for cristobalite formation.<br></div>At normal TLUD temperatures,
cristobalite is not formed.<br></div>The silica remains amorphous and is found
back in the biochar.<br></div>
<div>If the biochar is incorporated into the soil, the silica can eventually
be taken up by plants.<br></div>
<div></div>
<div>The silica came from the soil, and now it goes back to the
soil.<br></div>
<div>Simple. No?<br></div>
<div><br></div>Paul Olivier<br>
<div>
<div>
<div>
<div>
<div>
<div class="gmail_extra"><br><br>
<div class="gmail_quote">On Fri, Jun 14, 2013 at 7:57 AM, Kevin <span dir="ltr"><<a href="mailto:kchisholm@ca.inter.net" target="_blank">kchisholm@ca.inter.net</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT:#ccc 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex" class="gmail_quote"><u></u>
<div bgcolor="#ffffff">
<div><font face="Arial">Dear Paul</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">To comment on your important question:</font></div>
<div><font face="Arial">"<font face="Times New Roman">How would cristobalite
formation be avoided in a direct combustion unit processing a biomass that
has an appreciable content of amorphous silica?</font>",</font></div>
<div><font face="Arial">I would suggest for your consideration the possibility
of adding alkaline earths or metals to the rice husks, with a view to
forming harmless silicate compounds.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">1: The first one I would try is Ca(OH)2, or "Hydrated
lime". It might have "binding characteristics" that would enable you to
produce a pellet or "Rice Hull Aggregate" if some sort, but on combustion,
the CaO would certainly react with the SiO2, to produce "Calcium Silicate"
of some sort, having the generalized formula "XCaO.YSiO2" This would tend to
produce a pH neutral ash. Or, it might also yield an ash with cementatious
properties.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">2: Another approach you might try is to add a Sodium
or Calcium Bentonite Clay to the RH fuel, firstly to act as a
"binder/aggregator", and then to act as a "Silica Getter" during
combustion.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">3: You might even try sodium carbonate, as a 'silica
reactant. "</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">4: Iron Oxide has a strong affinity for silica also.
If you have a 'high iron clay", it might also be worth a try.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">Note that these are not necessarily "simple
suggestions." Too much of the alkalis may cause clinkering. Significant
experimentation may be required.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">Best wishes,</font></div><span><font color="#888888">
<div><font face="Arial"></font> </div>
<div><font face="Arial">Kevin</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial"></font> </div></font></span>
<blockquote style="BORDER-LEFT:#000000 2px solid;PADDING-LEFT:5px;PADDING-RIGHT:0px;MARGIN-LEFT:5px;MARGIN-RIGHT:0px">
<div>
<div style="FONT:10pt arial">----- Original Message ----- </div>
<div style="FONT:10pt arial;BACKGROUND:#e4e4e4"><b>From:</b> <a title="paul.olivier@esrla.com" href="mailto:paul.olivier@esrla.com" target="_blank">Paul Olivier</a> </div>
<div style="FONT:10pt arial"><b>To:</b> <a title="stoves@lists.bioenergylists.org" href="mailto:stoves@lists.bioenergylists.org" target="_blank">Discussion of
biomass cooking stoves</a> </div></div>
<div>
<div style="FONT:10pt arial"><b>Sent:</b> Thursday, June 13, 2013 9:21
PM</div>
<div style="FONT:10pt arial"><b>Subject:</b> Re: [Stoves] Burning wet
wood</div>
<div><br></div></div>
<div>
<div>
<div dir="ltr">
<div>
<div>Crispin,<br><br></div>My point of departure is a top-lit, updraft
gasifier that makes biochar. Everything that I have written previously has
to be understood in this light. This could be contrasted with a direct
combustion unit, but this was not my point at all. But direct combustion
units do not have a very great appeal among the Vietnamese.<br><br>I do
not think that I could interest very many households in Vietnam to switch
from bottled gas to a biomass fuel if I were to ask them to directly
combust biomass in their kitchens. Most Vietnamese might not make a lot of
money per month, but they are sharp, intelligent and enterprising. They
see direct combustion units associated with poverty. They are not
attracted to handling a messy biomass of a low bulk density, and there is
also a strong social resistance even against handling loose rice hulls.
This is especially true in an urban setting.<br><br></div>
<div>Rice is a major export item for Vietnam, and it is grown on over 80%
of the agricultural land in Vietnam. Therefore, Vietnam produces a lot of
rice hulls. In the highland areas where rice is not grown, we find coffee
husks. So for the Vietnamese, there are these two readily available fuels.
We also see rice hulls or coffee husks in many other Asian countries. Now
let me pose the following question to you.<br><br></div>
<div>Do you think that you could build a small direct combustion unit that
would handle loose rice hulls and loose coffee husks as neatly and cleanly
as a TLUD? I have seen many people who try to burn these two waste
products, but there is always a lot of smoke. The coffee husk is
especially nasty to combust. When burned, it emits a strong, black,
pungent smoke. I would insist that this direct combustion unit for rice
hulls and coffee husks not emit a whiff of visible smoke at any time
during its entire operation.<br><br>Finally I must caution that the direct
combustion of rice hulls is not ideal, since the ash might easily contain
cristobalite. How would cristobalite formation be avoided in a direct
combustion unit processing a biomass that has an appreciable content of
amorphous silica?<br><br></div>
<div>Thanks.<br></div>
<div>Paul<br></div></div>
<div class="gmail_extra"><br><br>
<div class="gmail_quote">On Thu, Jun 13, 2013 at 8:29 PM, Crispin
Pemberton-Pigott <span dir="ltr"><<a href="mailto:crispinpigott@gmail.com" target="_blank">crispinpigott@gmail.com</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT:#ccc 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex" class="gmail_quote">
<div link="blue" vlink="purple" lang="EN-CA">
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Dear
Paul O<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">I
am not sure why you think I am opposing the preparation of fuels. You
have mentioned it perhaps a dozen times in your last message as if it is
something I oppose. Because I have no idea why you think I oppose fuel
preparation – an essential part of most combustion I will address this
point.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Let
me set the record straight so you do not waste any more time telling me
that I oppose fuel preparation.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">I
fully agree that fuels need to be prepared. All fuels should be prepared
in some way – either tree branches cut to length for transport or split
to promote faster drying, chopping in certain cases or turning it into
pellets or briquettes for certain applications.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">I
not only fully agree with coal preparation, I have researched the
correct size that the raw coal should be in order to perform well in
certain ultra-low emissions stoves. The answer is a 10 to 15 g pellet
with well rounded edges so that it flows well under gravity without
shaking or vibration. This can be done with high volatiles coal without
adding any binder merely by getting the moisture and pressure of
formation correct. This was researched in South Africa by Prof Horsfall
(Shell Coal Chair, Wits Univ, JHB) and our fellow list member Prof
Philip Lloyd. Briquetting raw coal is an excellent way to deal with the
difficult of lowering emissions from very low priced
stoves.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">What
does not work well at all, proven over and over, is making semi-coked
briquettes and trying to promote that to households as a domestic fuel.
This product, which is nearly useless for cooking, is promoted over and
over as a ‘clean coal’ product. Time and again users find it is very
hard to light, requires a much larger fire to remain alight, must be
refuelled much sooner than unprocessed coal and is three times the price
required the whole industry to be subsidised. It does not ‘burn
cleaner’, it makes as much PM to light and makes more CO. To burn it
correctly it has to be reduced to the same optimal size and manufactured
with the volatiles intact so it can burn
properly.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<div>
<div>
<div>
<div>
<div>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><b><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt" lang="EN-US">></span></b>If you say "dirty coal" to someone in the
industry, they will understand exactly what you mean.<span style="COLOR:#1f497d"><u></u><u></u></span></p></div>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">They
will point to a coal their combustor cannot
burn.<u></u><u></u></span></p>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Obviously
there are coals from the edge of the field that are very difficult to
burn at all. In fact they call it ‘burned’ coal, meaning deteriorated. I
was involved slightly in the exploration of the Transkei coal fields
near MacClear in the early 80’s working with Heinemann whose PhD thesis
describes the field well. The edges of the deposits will not burn in a
domestic stove. That product is suited to >20 kW institutional stoves
that are never turned off. In short, the device is tuned to the
fuel.<u></u><u></u></span></p></div>
<div>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">></span>Every
body in the trade can tell you what a bad coal is, and they usually have
a good idea of what is needed to prepare it into a good coal for a
specific purpose. There are almost no coals coming out of the ground
that must not be prepared.<span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">I
am ‘in the trade’ and I think there is far too much ‘old boy
understanding’ of what a good or bad coal is. The best coal I have even
worked with is from Nalaikh mine: 25% moisture, 50% volatiles, 0.2%
Sulphur. This qualifies in the old school methods as a terrible, dirty,
bad coal.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">It
is one of the cleanest burning fuels available – but not when put into a
badly made copy of a Russian wood stove. It is really hard to produce
clinkers with it (high ash fusion temperature) and is very easy to
light. It will work in a TLUD or cross draft or downdraft stove and burn
clean enough to take the PM out of the ambient air. Show me a power
station running ‘clean good coal’ that will do that. The stoves being
promoted had lower CO per MJ than a new Eskom power station, lower PM
and of course a much greater system efficiency than using
electricity.<u></u><u></u></span></p></div>
<div>
<div>
<p class="MsoNormal"><span style="COLOR:#1f497d"><u></u><u></u></span> </p></div>
<div>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>But, Crispin,
just about all coal must be prepared. Also there is extensive blending
going on. Combustors generally are not designed to handle
everything.<u></u><u></u></p></div></div>
<div>
<p class="MsoNormal"><span style="COLOR:#1f497d"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">That
is correct – combustors are designed to handle particular fuels. Fuels
are prepared for particular combustors. We all know this. When fuels are
not matched to the stove or vice versa, it is not true that the fuels
are ‘dirty’. That is my point. In the wrong stove, biomass is a ‘dirty
smoky fuel’. At a ProBEC conference once there was a lady who was just
dead set against anyone burning wood because it was ‘a smoky
fuel’. It did not occur to her that there were more options than
an open fire.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<div>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">></span>Yes,
but please do not tell me the South Africans do not do extensive coal
preparation. <span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">That
is why I said nothing about that. I am not sure where you are coming
from. Coal is always prepared, usually by
sizing.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<div>
<div>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>Yes, there
are power stations designed to burn coal of a 40% ash. But often they
have little choice in doing so. <span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Correct.
They design burners to go with the fuel. Until then, the fuel is ‘bad’ –
is that correct? Then it becomes ‘good’?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<div>
<blockquote style="BORDER-BOTTOM:medium none;BORDER-LEFT:#cccccc 1pt solid;PADDING-BOTTOM:0mm;PADDING-LEFT:6pt;PADDING-RIGHT:0mm;MARGIN-LEFT:4.8pt;BORDER-TOP:medium none;MARGIN-RIGHT:0mm;BORDER-RIGHT:medium none;PADDING-TOP:0mm">
<div>
<div>
<div>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">>>Imagine
trying to design a biomass stove that was tuned to each type of fuel
that happened to be available…oh wait…that is exactly what is
happening on this list! What a surprise, again. Is that not exactly
what you are
doing?</span><u></u><u></u></p></div></div></div></div></blockquote></div>
<div>
<div>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>Not at all.
That is precisely what I am opposing. <span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">What
exactly are you opposing? It is not at all clear. Are you opposing
stoves that can burn unprocessed fuels? Are you opposing stoves that
only burn one fuel?<u></u><u></u></span></p>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">></span>Crispin,
I challenge you to put coconut powder or fine sawdust into the best TLUD
that you can design. <span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Why
would I try to burn fine sawdust in a TLUD? There is nothing magical
about a TLUD. There are plenty of bad TLUD’s. Fine sawdust burns
perfectly well in a blown burner and there is a very fine ceramics
factory in Malawi that uses such a burner – two of them actually. Just
because a fuel doesn’t burn well in a TLUD does not mean the fuel is
‘bad’ or ‘dirty’.<u></u><u></u></span></p>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>Then tell me
if air is going to flow up through this fine biomass in a uniform
manner. <span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">It
is not going to, that is why a TLUD is not suitable for burning that
fuel. Use something more appropriate.<u></u><u></u></span></p>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>Tell me that
there will be minimal CO2 present in the outgoing syngas. <span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Why
should we have to produce syngas? Is this based on the idea that only a
TLUD gasifier can burn cleanly??<u></u><u></u></span></p>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>Also the
device you design has to be small and easy to use. It cannot occupy an
entire corner of your kitchen, and no part of it should be situated
outdoors. Go for it.<span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">That’s
silly. I will choose my own design criteria, thank you very much. The
challenge is to burn a fuel properly in a way convenient to the user.
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<div>
<div>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>However, if
we pelletize the coconut dusk or the wood shaving, air flows up through
it in a uniform manner, and we have an incredibly simple reactor that
weighs less than 1.2 kg. It can be in continuous operation for up to 1.5
hours.<u></u><u></u></p></div></div>
<div>
<p class="MsoNormal"><span style="COLOR:#1f497d"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">That
is one solution. Go for it. See if people want to buy it. If they do,
you have a winner. If it tests well, I will promote it. Testing will
include user acceptance, emissions and durability, cost and
controllability.<u></u><u></u></span></p></div>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<div>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">></span>Ok,
then show me a TLUD operating on loose coconut dust or fine sawdust.
<span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Why
would I bother trying to burn in in a TLUD? They are batch loaded. They
are hard to control, they can’t really be turned off. A TLUD is
very finicky about the fuel – in fact the fuel can be considered a
significant part of the stove. Fuel preparation is so onerous that when
we tried late last year to talk about ‘improved stoves’ in Central Java,
the group of women immediately, loudly and without prompting, told us
firmly that we should <i>not</i> bring to them any stove that required
extensive fuel preparation, “especially chopping wood into small
pieces”. They were simply <i>not</i> willing to do that, they
said.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">It
seems someone had been there before us.<u></u><u></u></span></p>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>There should
be relatively little CO2 in the syngas<span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Why
make syngas? Why not just burn the fuel? This gasifier thing is getting
out of hand. We are not trying to supply town gas we are trying to cook.
If you don’t separate the fire from the fuel many problems are
eliminated. Close-coupled semi-gasifiers avoid all sorts of problems for
this reason.<u></u><u></u></span></p>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>It should
also make a uniform biochar. <span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">What
on earth for? Having collected all the fuel and dried it, with effort,
and handled it into the stove, why would I not burn it? The economic
argument about char in the soil may well be shown, in future, to be
valid. Until then it is arm waving. If char helps soil, make a reactor
that is smokeless and make it at scale. Cheaply, locally, and apply it
without transporting to the kitchen and back. In your special
circumstances, which are hardly universal, you have a local market – go
for it. Don’t advertise it for people for whom it is completely
inappropriate.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<div>
<blockquote style="BORDER-BOTTOM:medium none;BORDER-LEFT:#cccccc 1pt solid;PADDING-BOTTOM:0mm;PADDING-LEFT:6pt;PADDING-RIGHT:0mm;MARGIN-LEFT:4.8pt;BORDER-TOP:medium none;MARGIN-RIGHT:0mm;BORDER-RIGHT:medium none;PADDING-TOP:0mm">
<div>
<div>
<div>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">>></span><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">We
do not focus enough on how to design good stoves and hope that
preparing the fuel will compensate for our collective ignorance.
</span><u></u><u></u></p></div></div></div></blockquote></div>
<div>
<div>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>No, but we
can make things infinitely complicated and expensive if we do not
prepare fuels correctly. <span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">So,
prepare the fuels. Nothing wrong with that if people are willing to do
it.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<div>
<div>
<p class="MsoNormal"><span style="COLOR:#1f497d">></span>Ok, then put
Mongolian coal, of a 30% moisture content and of all shapes and sizes,
into a TLUD, and tell me if you are going to get a beautiful flame with
no CO2 formation in the synas. <span style="COLOR:#1f497d"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">You
are mixing two things: a decent burn and gas production. No Mongolian is
trying to make syngas in a TLUD. I doubt they know what the term ‘TLUD’
means, 99% of the TLUD users. It is just a stove. It burns
“</span>Mongolian coal, of a 30% moisture content and of all shapes and
sizes” <span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">and
they do it hundreds of thousands of times a day. Emissions are down more
than 90% against the baseline. If they would prepare the fuel into small
round briquettes, PM would drop another order of magnitude. Is there any
other project that has a) as many TLUD’s promoted? As much reduction in
the local environmental PM? As much an advance over the baseline? As
little attention? <u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div>
<div>
<div>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><span style="COLOR:#1f497d">></span>The TLUD works superbly on both rice
hulls and coffee husk because these materials are uniform and generally
do not require preparation. When hulled, coffee cherries and rice hulls
are at a 12% moisture, and air flows up through them within the reactor
in a uniform manner. <span style="COLOR:#1f497d"><u></u><u></u></span></p></div>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">So
what you are saying is that when the fuel is perfectly prepared, it
happens to work well with a particular type or types of TLUD. How is
this going to assist us all? We cannot prepare all the fuels available
so they will suit a certain burning technology. The technology is much
easier to change than 99% of the fuels.<u></u><u></u></span></p>
<div>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><span style="COLOR:#1f497d">></span>I venture to say the TLUD will work
well on most types of irregular biomass provided they are properly
prepared. This measn that the one stove could handle almost any type of
properly prepared biomass.<span style="COLOR:#1f497d"><u></u><u></u></span></p></div>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">An
approach specifically and heartily rejected by our target audience. They
are drowning in biomass and they are not interested in a) paying for
fuel and b) preparing it to fit what someone happens to be making as a
combustor. Far easier to change the combustor. Develop once. Buy once,
problem solved. <u></u><u></u></span></p></div></div>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">That
is my point.<u></u><u></u></span></p>
<p style="MARGIN-BOTTOM:12pt" class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Regards<span><font color="#888888"><br>Crispin<u></u><u></u></font></span></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"><u></u><u></u></span> </p></div></div></div></div><br>_______________________________________________<br>
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