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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p><o:p> </o:p></p><p><span style='font-family:"Liberation Sans",serif'>Naphthalene in Producer Gas</span><o:p></o:p></p><p><o:p> </o:p></p><p><span style='font-family:"Liberation Sans",serif'>Hi Gasification Colleagues,</span><o:p></o:p></p><p><span style='font-family:"Liberation Sans",serif'>Reading through the Italian Paper on gasifier monitoring in South Tyrol</span><span style='font-family:"Liberation
Sans",serif'>, the reference to Naphthalene caught my eye, because as a light pyrolysis oil, after dry filtration and condensation, I have only seen this in gas in the Northern hemisphere. Looking like yellow oil floating on aqueous condensate, exposed to air when tipped onto a concrete surface, it just completely vaporizes leaving only a carbon trace of stain. It makes a good mess inside pipes and diaphragm regulators and if being combusted in a flare or oxidation chamber, will add to the emissions from the stack. The bottom line is that we don't want this in our producer gas for either engine or combustion applications, but once condensed, it's very hard to clean out of the gas.</span><o:p></o:p></p><p><span style='font-family:"Liberation Sans",serif'>My questions to any one who might have some similar experience, is why Naphthalene may not show up in small gasifiers under say 100m3/hr, yet becomes a issue as the gas output increases from a larger system. I have observed this formation in N.Ireland and California and definitely related to just higher output. Could it be related to the amount or volume of the unstable pyrolysis gas in the fuel hopper? Can this create a chemistry that can survive an incandescent char bed, but reform as Naphthalene in the gas reduction phase? </span><o:p></o:p></p><p><span style='font-family:"Liberation Sans",serif'>I can assure you that it isn't about tar or bad design, as our bed analysis and pressure drop continuous monitoring has not shown bridging or channeling to be the culprit. Black tars are never present, nor is CH4 as Methane (<2%), so bed temperatures are not an issue, nor moisture content of the fuels (wood chips or blocks). Char under the grate is dry and clean, as is the <10 micron dust from the cyclones.</span><o:p></o:p></p><p><span style='font-family:"Liberation Sans",serif'>The photos show two samples from a larger system, one a first stage cooling containing ash and carbon with a purple colour from the ash. The second bag from the cooling condenser is yellow from the Naphthalene which did increase with more gas output . The square container is completely clear and comes from the Fluidyne Pacific Class gasifier (90m3/hr) and it has always made clear condensate in both hemispheres except when incorrectly fueled. It has not been possible to test larger gasifiers of our own design here in New Zealand, hence the questions.</span><o:p></o:p></p><p><span style='font-family:"Liberation Sans",serif'>Any discussion would be appreciated.</span><o:p></o:p></p><p><span style='font-family:"Liberation Sans",serif'>Doug Williams,</span><o:p></o:p></p><p><span style='font-family:"Liberation Sans",serif'>Fluidyne.</span><o:p></o:p></p><p><o:p> </o:p></p><p><o:p> </o:p></p><p><o:p> </o:p></p><p><span style='font-family:"Liberation Sans",serif'> </span><o:p></o:p></p></div></body></html>