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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>Dear Stovers,<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Reading the book “Biomass Gasifier “Tars”” explains and illustrates the complexity of measuring Tars. Many very different collection procedures, extraction steps and reporting units and it seems it all ends up very confusing. I don’t know how we can use gravimetric units on gas samples when there is such a wide range of organics. And the distribution and make-up of the organics change as the gases leave the combustion chamber and cool. It’s a very good book for us on a steep learning curve and those wanting to compare different systems by showing the complexity of reporting and extractions.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Because we want combustion to convert all organic carbon to CO2 (or CO in pyrolysis gas) It seems to me the definition of tar should be the ‘oxygen demand’ of the gas just as it leaves the gasifier or combustion chamber. Forget the structure of the organics for other research. We could run a gas sample mixed with oxygen through a metal tube with heated coil inside and determine the increase in CO2 from going in to the exit. The tube could be heated to increasing temperatures to separate the tars into Primary, Secondary and Tertiary products. Or separate using a hot tube at different length Or differing flow rate. The reported units would be in [ mg O2 demand per Nm3 ]. Knowing the CO and CO2 going in we can calculate the Tars in the sample based on the CO2 increase in the out gas reported on oxygen demand. Sampling at the point just after the exit of the combustion chamber or gasifier (before any work has been done) means most of the tars are still in the gas phase.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>At least this way we will have a common base we can all start at. Then additional research is done to quantify the types of organics and the changes that take place as use and cooling takes place down the ‘train’. <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Anyways – if I had a lot of money and time this is what I would research…. <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Frank<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Frank Shields<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>42 Hangar Way<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Watsonville, CA 95076<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>(831) 724-5244 tel<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>(831) 724-3188 fax<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>frank@bioCharlab.com<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p></div></body></html>