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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='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Toby,<o:p></o:p></span></p><p class=MsoNormal style='margin-top:4.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>There is no difference, really, between pressure and vacuum. If we just start to think of anything that has no pressure at all as Zero Pressure; normal Atmospheric Pressure as 14.69 PSIA (PSI absolute) and so forth, then we won’t get into trouble. Pump sizing always considers the Absolute Pressure (e.g. PSIA) at the inlet and outlet, not the Gauge pressure (e.g. PSIG). A third concept is Differential Pressure (e.g. PSID). A pump increases the pressure (measured across the Inlet and Discharge Ports) as a differential pressure gain, more-or-less irrespective of the Absolute Pressure environment that it operates in.<o:p></o:p></span></p><p class=MsoNormal style='margin-top:4.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>There is really no such thing as “Vacuum” conveying. This only refers to the fact the transport network operates at or below the ambient pressure and is operated this way to help reduce fugitive losses of transported materials. A vacuum cannot move anything; it is the force of pressurized gas behind the transported material that provides the propulsive energy. In the case of a conveying system connected to a positive-displacement “vacuum” blower, the force is a maximum of 14.69 PSI, enough to “lift” a water column 33.9 feet, hardly any stretch at all for a pump, though the work done will be the same regardless of the method used.<o:p></o:p></span></p><p class=MsoNormal style='margin-top:4.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>When someone says: “Gravity doesn’t exist; the world sucks!”, this is a very special case of the above that awaits the practical manipulation of anti-gravity.<o:p></o:p></span></p><p class=MsoNormal style='margin-top:4.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Best, Mark<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><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-bounces@lists.bioenergylists.org [mailto:gasification-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Toby Seiler<br><b>Sent:</b> Sunday, February 27, 2011 3:42 PM<br><b>To:</b> gasification@lists.bioenergylists.org<br><b>Subject:</b> [Gasification] Benefits of boosting compression ratio with producer gas<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0><tr><td valign=top style='padding:0in 0in 0in 0in'><div><p class=MsoNormal>Sorry Tom, I didn't ask the question correctly (or I may be off in left field). This comes from some time spent in a place called Flow Dynamics Laboratory where inlet design of blowers was being tested. My application was sawdust material moving. Dan, the owner, explained how pressure was much more effective than vacuum for moving mass. He explained that drag in a vacuum is hard to overcome, while pressure fills the space with molecules and can push materials great distances. <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>When talking engines, for example on my 74 Ford f600, I watch the vacuum gage and see that it is around 18-22" of vacuum, warmed up 1200 rpm or so (driving hydraulic pump). So what goes to the cylinders is not atmospheric pressure, it is around half, perhaps less. <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>I'm trying to understand how engine efficiency is related to both air and gas pressure and density. If producer gas is operating with 18/1 in a normally aspirated engine, due to high octane, how will the ratio be affected if one has positive pressure at one or two pounds? <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>Seemingly this would involve air flow across an orifice, similar to a butterfly valve (throttle), but I am at a loss for a good start point. <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>Given a large quantity of air and gas to make comparable power (not large derated), the flow of air/gas in a large displacement engine would seem to be a much more critical factor than just saying the cylinder is seeing atmosphere pressure and forgetting the drag that manifolds, throttle valves and pulling gas from a gasifier creates (in a suction system). I can hardly see a direct linear relationship. <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>My work is a low pressure system, so this is not an academic or theoretical discussion that I will never act on and I'm at a point of determining engine for a CHP and what internal modifications to plan, if any. I have several engines, a 345 International, a 460 Ford, a Cumins 5.7 (with needed repair), a 7.3 International (in a ford truck also needing repair). <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>Sorry if this is confusing or not cogent. I'm trying.<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>Toby<o:p></o:p></p></div><div><p class=MsoNormal>seilertechco <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div></td></tr></table><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p></div></body></html>