<div dir="ltr"><div><div>Mark,<br><br></div>I am thinking back to an early email exchange with Doug where he told me that an absence of visible smoke doesn't necessarily mean clean combustion. My experience at the Decathlon has reinforced that comment. I am very much still learning but it seems to me that low emission combustion of wood is still seen as dirty by legislators so it needs to get much cleaner. <br>
<br>In New Zealand, and from what I read also the USA, emission laws are getting tougher and bans on wood burners still being seen and implemented as a solution. I listened to one air scientist here apply the term "decommissioning" and this was the only solution he offered. In the long run the battle I face for retrofits is against this type of thinking, I can only hope my zero emission result starts to make waves in official circles.<br>
<br></div><div>Knowing what I now know I don't think a vitreous shield is sufficient, better techniques to maintain flame temperature are necessary. I certainly haven't found it an advantage with a retrofit anyway.<br>
<br></div><div>So yes I do think heat recovery on the exhaust is the way forward, get the combustion complete before any heat is removed. <br><br>Of course the holy grail of long burn times is always a goal that complicates matters, in particular engineering that into a simple low cost system. It is going to be hard to beat automated feed systems to achieve that along with zero emissions but a jet stream type water jacket may make it possible. I will certainly give it a go when I have the R&D resources available to me.<br>
<br></div><div>I think low emissions and greater efficiency is always a relevant topic and useability quite an appropriate discussion also :-) <br></div><div><br></div><div>Cheers<br><br>Jason<br><br></div><div>PS. I have one aquaintance in New Zealand that is challenging the science around respiratory disease and emissions from wood smoke. He says the link is tenuous and the early bogus studies keep getting repeated and used as justification to ban wood stoves.<br>
</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sat, Dec 28, 2013 at 8:33 PM, Mark Ludlow <span dir="ltr"><<a href="mailto:mark@ludlow.com" target="_blank">mark@ludlow.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div link="blue" vlink="purple" lang="EN-US"><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hi Jason,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Using a vitreous shield (Dick Gallien’s solution) seems functionally sensible but it confuses the heat-transfer analysis a bit. If this is a stove (rather than a char producer or gasifier) where we idealize a clean exhaust, robbed of all of it sensible heat. Hmmm… Are heat recovery coils or perhaps plate heat-exchangers on the exhaust the only way to go? Naturally, all of this deviates a bit from pyrolysis and gasification…<br>
<br>I like your targeting of retrofits!<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal">
<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Best, Mark<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> Gasification [mailto:<a href="mailto:gasification-bounces@lists.bioenergylists.org" target="_blank">gasification-bounces@lists.bioenergylists.org</a>] <b>On Behalf Of </b>Jason<br>
<b>Sent:</b> Friday, December 27, 2013 10:48 PM</span></p><div><div class="h5"><br><b>To:</b> Discussion of biomass pyrolysis and gasification<br><b>Subject:</b> Re: [Gasification] Wood heating in the UK - whole log gasification<u></u><u></u></div>
</div><p></p><div><div class="h5"><p class="MsoNormal"><u></u> <u></u></p><div><div><p class="MsoNormal" style="margin-bottom:12.0pt">To all,<br><br>my experience with top feeding systems is keeping the upper ends of the fuel from pyrolysing too early. A water jacket is a logical solution so the link to the jetstream is interesting for me as I have not come across that before.<br>
<br>When taking a look at some of the alternate designs at the bottom of that wikipedia page I am reminded of one discussion with a judge at the wood stove decathlon. He advised of the terrible pollution problem from poorly designed boilers, something I had seen discussed but had not explored in depth. The Alliance For Green Heat is in the thick of combating the problem. When the problem of combustion chambers surrounded by water jackets was explained the problem was immediately apparent, the combustion just doesn't get hot enough or for long enough to be complete. So yes a water jacket but its integration into the design has to be carefully considered. The plans for an ultra clean design are in my head now as a consequence of that discussion :-) <u></u><u></u></p>
</div><div><p class="MsoNormal">Jason<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div></div><div><p class="MsoNormal" style="margin-bottom:12.0pt">
<u></u> <u></u></p><div><p class="MsoNormal">On Sat, Dec 28, 2013 at 2:10 PM, Tom Miles <<a href="mailto:tmiles@trmiles.com" target="_blank">tmiles@trmiles.com</a>> wrote:<u></u><u></u></p><blockquote style="border:none;border-left:solid #cccccc 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in">
<div><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Alex,</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I was thinking of Dick’s Jetstream. He employed a lot of good combustion principles to stick wood burning at a time when we were just migrating from the “tin wonder” wood stoves. </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I didn’t realize that there was a Wikipedia page on it.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Thanks</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Tom </span><u></u><u></u></p>
<p class="MsoNormal"><a name="143382095fbc920b_14336c12fd5b097c__MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></a><u></u><u></u></p><div><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Gasification [mailto:<a href="mailto:gasification-bounces@lists.bioenergylists.org" target="_blank">gasification-bounces@lists.bioenergylists.org</a>] <b>On Behalf Of </b>Alex English<br>
<b>Sent:</b> Friday, December 27, 2013 4:41 PM<br><b>To:</b> Discussion of biomass pyrolysis and gasification</span><u></u><u></u></p><div><p class="MsoNormal"><br><b>Subject:</b> Re: [Gasification] Wood heating in the UK - whole log gasification<u></u><u></u></p>
</div></div></div><p class="MsoNormal"> <u></u><u></u></p><div><p class="MsoNormal">Ken,<u></u><u></u></p><div><div><p class="MsoNormal"><br><br>If you haven't already heard of the Jetstream<br><span style="font-size:10.0pt;font-family:"Arial","sans-serif";background:white">The wood was loaded into a vertical tube which passed through the water jacket into a refractory lined combustion chamber. In this chamber the burning took place and was limited to the ends of the logs. The water jacket prevented the upper parts of the logs from burning so they would gravity feed as the log was consumed.</span><br>
<br><a href="http://en.wikipedia.org/wiki/Jetstream_furnace" target="_blank">http://en.wikipedia.org/wiki/Jetstream_furnace</a><br><br>Not a chimney powered stove.<br><br>Alex<br><br><br>On 27/12/2013 6:47 PM, Jeff Davis wrote:<u></u><u></u></p>
</div></div></div><div><div><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><p class="MsoNormal" style="margin-bottom:12.0pt">Hi Ken, <br><br><br><br>Thanks for the interest! <br><br><br><u></u><u></u></p><p class="MsoNormal" style="margin-bottom:12.0pt">
This is my main unknown as yet, how would a split log combust and pyrolise, if presented to the ember bed, cut end first. I suspect that there would be little penetration of heat axially, directly through the end, because the ring structure presents a tough barrier. Therefore, most burning would have to come radially, and so air nozzles would have to be positioned to act radially on the sides of the log. <u></u><u></u></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><br>OK, I should try cutting the wood at 45 deg instead of 90. Interesting! <br><br><br><u></u><u></u></p><p class="MsoNormal" style="margin-bottom:12.0pt">In your design, it looks similar to a Rocket, but with the fuel container near vertical. However, the top loading hatch looks fairly airtight? - so unlike a rocket, there is no air drawn through fuel. <u></u><u></u></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><br>The next test run will be at almost vertical and more distance between the tube and grate. <br><br>This has only run for short periods of time but once it's burning OK I have been leaving it up. In the middle of the door is an adjustable air inlet. It's rusted open because of the nasty acidic coal that was burned in it for a few years. <br>
<br><br><u></u><u></u></p><p class="MsoNormal">Nevertheless it appears to burn well and produces a healthy amount of good sized charcoal. I would be very interested to know how it copes with a larger log. Perhaps by way of experiment, one could be loaded, instead of the 2" material, to see how it fairs - this would be very useful information. <u></u><u></u></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><br><br>In due time. <br><br><br><br><br>Best wishes, <br>Jeff <br><br>_______________________________________________ <br>Gasification mailing list <br><br>to Send a Message to the list, use the email address <br>
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