<div dir="ltr"><div>Hi Ronal:</div><div><br></div><div>By way of explanation, these appliances are house heaters and are very removed from gasifier type single pot cooking stoves. A typical mass is in the 2,000 - 4,000 kg range, which is used as thermal mass (heat storage). Here are some examples:<br><a href="http://mha-net.org/html/gallery2.html">http://mha-net.org/html/gallery2.html</a><br></div><div>Batch fuel loads are 15 - 30 kg., once or twice per day. Biochar has never been a consideration, and I only got interested in it recently.</div><div><br></div><div>They typically have a flue damper which needs to be closed to retain the heat. This means all the charcoal has to be burned, or you risk carbon monoxide poisoning. Some countries like Germany and Austria don't permit flue dampers due to the potential safety issue.</div><div><br></div><div>With an underfire air system (grate), burning up charcoal is easy, but underfire air was found to be dirty once we started measuring PM and CO.</div><div><br></div><div>For the last couple of years I have experimented with using an airtight system, like the Austrians, that allows the combustion to be stopped by shutting off the combustion air and also preventing flow through the chimney. This can be done at any time once the batch has burned the volatiles and is into charcoal mode. This is a huge convenience, because you can walk away and don't have to worry about closing a flue damper too early. Coincidentally, the tighter you can manage to make it, the more charcoal you can make. The next morning, there may still be some live coals and I scoop all the remains into a metal ash bucket with a tight lid, that extinguishes everything. Somewhat similar to the bottom part of a Kon Tiki kiln. Charcoal yield is roughly 5% by weight.<br></div><div><br></div><div>Contraflow refers to a particular way of running the internal heat exchange channels, ie downdrafting. It is native to Finland. Combustion is complete by this time. In the traditional Austrian system, the firebox has less height and immediately downdrafts before entering additional heat exchange flue channels. With this setup you get very good mixing in the flames in the downdraft channel this way.</div><div><br></div><div>Norbert<br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Jul 27, 2018 at 5:00 PM, Ronal W. Larson <span dir="ltr"><<a href="mailto:rongretlarson@comcast.net" target="_blank">rongretlarson@comcast.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div>Norbert and list:</div><div><br></div><div><span class="m_-8194949261018758151Apple-tab-span" style="white-space:pre-wrap"> </span>1. Thanks for the historical review and comments.</div><div><br></div><div><span class="m_-8194949261018758151Apple-tab-span" style="white-space:pre-wrap"> </span>2. I hope you can add a few more comments from the MHA and SNEWS perspectives on the relationship between top lighting and char-making. I know that you have yourself been making char in your own MH - and perceive that to be fairly unusual for your profession. Specifically, in the 1992 time period, was there anyone doing top lighting for char-making purposes? </div><div><br></div><div><span class="m_-8194949261018758151Apple-tab-span" style="white-space:pre-wrap"> </span>3. You wrote: "<i>At Toronto we talked with Tempcast, who told us that they
have abandoned their underfire air completely and are developing a new air
system based on top down burning."</i></div><div><span class="m_-8194949261018758151Apple-tab-span" style="font-style:italic;white-space:pre-wrap"> </span>On this list, top lighting always (??) refers to char-making first (emphasize first). Many of the commercial stoves like the Phillips and the Mimi Moto, adjust air flows when the pyrolysis front hits the bottom and then consume the char. We have been told that the Dutch developer of the Phillips regularly (?) did stop his own personal unit when the pyrolysis front reached the bottom - and did save the char.</div><div><span class="m_-8194949261018758151Apple-tab-span" style="white-space:pre-wrap"> </span>My question on this sentence is whether we should call this operation more like a kon tiki - which has zero "underwire air". Can you say more about the Tempcast "<i>new air system". </i> I am suggesting here there may have been top-lighting but not up draft. And presumably Tempcraft was not interested in making char/</div><div><br></div><div><span class="m_-8194949261018758151Apple-tab-span" style="white-space:pre-wrap"> </span>4. Also can you say something about the term <i>"contraflow" </i> in this sentence: <i> "Elsewhere in this issue you'll find a report on some initial testing we did on
contraflow heaters at Jerry Frisch's new lab." </i>This sounds like it might have been a downdraft system. On this list we only hear from Gordon West and Bill Knauss with their continuous TLUD, in which the pyrolysis front is stationary, because the fuel is being continuously fed upwards. They are optimizing towards char production. Could your "contraflow" approach produce char?</div><div><br></div><div>Thanks again for this and other great contributions to this list.</div><div><br></div><div>Ron</div><div><br></div><div><br></div><br><div><blockquote type="cite"><div><div class="h5"><div>On Jul 27, 2018, at 1:30 PM, Norbert Senf <<a href="mailto:norbert.senf@gmail.com" target="_blank">norbert.senf@gmail.com</a>> wrote:</div><br class="m_-8194949261018758151Apple-interchange-newline"></div></div><div><div><div class="h5"><div dir="ltr"><div>Just to add a somewhat random historical data point on the TLUD discussion:</div><div><br></div><div>Masonry Heater Association first published an article on top ignition for updraft batch burns in masonry heaters in 1991.<br></div><div>Here's my follow up article from 1992:<br><a href="http://mha-net.org/docs/v8n2/docs/TOPDOWN.pdf" target="_blank">http://mha-net.org/docs/v8n2/<wbr>docs/TOPDOWN.pdf</a></div><div><br></div><div>It has become a mainstream ignition method for wood stoves and fireplaces since then. <br></div></div></div></div>
______________________________<wbr>_________________<br>Stoves mailing list<br><br>to Send a Message to the list, use the email address<br><a href="mailto:stoves@lists.bioenergylists.org" target="_blank">stoves@lists.bioenergylists.<wbr>org</a><br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br><a href="http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org" target="_blank">http://lists.bioenergylists.<wbr>org/mailman/listinfo/stoves_<wbr>lists.bioenergylists.org</a><br><br>for more Biomass Cooking Stoves, News and Information see our web site:<br><a href="http://stoves.bioenergylists.org/" target="_blank">http://stoves.bioenergylists.<wbr>org/</a><br><br></div></blockquote></div><br></div></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature" data-smartmail="gmail_signature">Norbert Senf<br>Masonry Stove Builders<br>25 Brouse Road, RR 5<br>Shawville Québec J0X 2Y0<br>819.647.5092<br><a href="http://www.heatkit.com" target="_blank">www.heatkit.com</a></div>
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