<div dir="ltr"><div dir="ltr">Crispin: <br><br>Of course biomass has N, but for other fuels combusted at high enough temperatures, the N comes from air. <br><br>That's what I remember from my utility regulatory and climate beancounting work. <br><br>Biomass burnt at over 820 C probably oxidizes nitrogen in the air, depending on air supplies. <br><br>Am I wrong? <br><br>Copying Andrew and Harold in case my foolishness needs to be checked again. <br><br>Nikhil<br><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><font face="georgia, serif">------------------------------------------------------------------------<br>Nikhil Desai</font></div><div><span style="font-family:georgia,serif;font-size:small">(US +1) 202 568 5831</span><font face="georgia, serif"><br><i>Skype: nikhildesai888</i><br></font><br></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Mar 5, 2019 at 9:36 PM Crispin Pemberton-Pigott <<a href="mailto:crispinpigott@outlook.com">crispinpigott@outlook.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div name="BB10" id="gmail-m_-8709489697284904690BB10_response_div_BBPPID" dir="auto" style="width:100%">Having recently been invited to explain NOx formation and getting rid of it after it formed, I had a chance to discuss this with Prof Annegarn when in China. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">The N comes from the fuel and most N in fuel becomes NO even if there is not enough O in the fuel to create it. In the case of biomass there is plenty. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">After NO is created, it can be converted to N2 and O2 which frees the O to move on to join H or C. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">If it is kept above about 820 C for 250 milliseconds it will go that way, or can. Low NOx burners are of two types: those that convert NO to N2 and those that prevent the formation
of NO2 at a much higher temperature. It is actually not very helpful to discuss all NOx as if it was similar and certainly not helpful if you are trying to minimize production of it. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">You can use a low-N fuel.</div>
<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">You can use a chamber hot enough to convert NO to N2. </div>
<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">You can keep the uppermost temperature below 1250 C. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">NO forms easily in a gasifier or fire because the N and O are already joined together in the cellulose with several combinations easily formed. N is often joined to three oxygen
atoms with a valence of 4. One of them is joined by a double bond so taking off the two with single bonds, you have NO with a double bond. N2O a has a valence of 1 for the N and it can be dealt with. NO2 has a valence of 4 for the N and it is "unhappy" because
it likes 3 or 5 but the oxygen is satisfied by its complete shell (octet). </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">It is 2 with NO so keeping it hot and providing a second NO gives N2 and O2 which happens if given time and temperature. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">N2 has a triple bond and is very stable. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">As for fuels, the amount of chlorophyll can be used as a vague indicator of the N content so leaves have far more and wood far less than average for a whole plant. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">Therefore we expect pellets made with leafy material (corn stover) to have much more NO in the exhaust compared with wood pellets. If the combustor is properly constructed, it can
be greatly reduced. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">I only have detailed tests for coal fires in which the conditions are good for NO reduction. The effect is pronounced: exhaust that would otherwise have an emission factor of 600
ppm (undiluted sample) can be reduced to the low 200's with combustion chamber design alone. Let's call it a 60% reduction. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">It is quite important to remember that a stove fuel combination has inherent emissions, and accidental emissions, and some like NO which are from an inherent elemental component
but which like Sulphur, can be emitted in less or more polluting forms. Poor combustion of S gives H2S when it should be SO2. N should be N2 not some other molecule. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">Just because NO (and CO) forms easily doesn't mean we have to "accept it".we can play a few tricks. </div>
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<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">Regards </div>
<div name="BB10" id="gmail-m_-8709489697284904690response_div_spacer_BBPPID" dir="auto" style="width:100%">Crispin </div>
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<div id="gmail-m_-8709489697284904690from"><b>From:</b> <a href="mailto:winter.julien@gmail.com" target="_blank">winter.julien@gmail.com</a></div>
<div id="gmail-m_-8709489697284904690sent"><b>Sent:</b> March 5, 2019 6:54 PM</div>
<div id="gmail-m_-8709489697284904690to"><b>To:</b> <a href="mailto:peetersfrans@telenet.be" target="_blank">peetersfrans@telenet.be</a>; <a href="mailto:stoves@lists.bioenergylists.org" target="_blank">stoves@lists.bioenergylists.org</a></div>
<div id="gmail-m_-8709489697284904690cc"><b>Cc:</b> <a href="mailto:franke@cruzio.com" target="_blank">franke@cruzio.com</a>; <a href="mailto:Crispinpigott@outlook.com" target="_blank">Crispinpigott@outlook.com</a>; <a href="mailto:boll.bn@t-online.de" target="_blank">boll.bn@t-online.de</a></div>
<div id="gmail-m_-8709489697284904690subject"><b>Subject:</b> Re: FW: [Stove NOX // ACRYLAMIDE</div>
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<div dir="ltr">Hi All;
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<div>I have not looked into it in detail, and certainly not in the last three years. However, in the back of my mind, NOx can form in freeboard flame area of moving grate gasifiers when there are higher amounts of excess (above stoichiometric requirements) air.
I expect that this would be a larger problem with fuels that are high in nitrogen. This could arise for biomass stoves that burn compressed fuels that have higher amounts of leafy material or dung.</div>
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<div>Cheers,</div>
<div>Julien.</div></div></div></div></div>
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