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<DIV dir=ltr><FONT color=#000000 size=2 face=Arial>Dear Andrew </FONT></DIV>
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<DIV dir=ltr><FONT face=Arial>To me this a kiss of the death.</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial>I started my carier developing screew pyrolysis units at the technical universty of Copenhagen for two purposes - one the Viking gasifier - 2 a starw pyrolysis unit. </FONT></DIV>
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<DIV dir=ltr><FONT face=Arial>1. It is limited in temperature bedause of material limitations in the steel -</FONT></DIV>
<DIV dir=ltr><FONT face=Arial>2. It is limited in capacity due to heat tarnsfer limitations om both sides</FONT></DIV>
<DIV dir=ltr><FONT face=Arial>3. It is hot mowing part inside that has a limited lifetime due to reduced strenght </FONT></DIV>
<DIV dir=ltr><FONT face=Arial>4. Everywhere you cool eg for bearings tar condenses and cause problems. </FONT></DIV>
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<DIV dir=ltr><FONT face=Arial>1. Maks temperature on the steel plate is 600 oC if you expect life times of years even for soem of the most expensive types of refracotory metals. The consequense of that is that mea temperatue inside the biomass will be well below 600 oC having the consequense that almost no gasification takes place.</FONT></DIV>
<DIV dir=ltr><FONT face=Arial>2. Energy transfer is in the order of 3-4 KW/m2 havinf the consequense that you can pyrolyse 5-10 kg pr hour pr m3 at a mean temperature of 500 oC - thus a Range fuel pyrolyser should have been 4-800 m2 to PYROLYSE (not gasifiy) 4000 kg pr hours. Assuming this made of a 600 mm pipe with a screew inside it is a 2-400 meter long pipe !!! - imagine the termal stresses in such a construction - and even worse thermal transients!!</FONT></DIV>
<DIV dir=ltr><FONT face=Arial>3. Imagine 18 pipes in series stacked on top of each other you feed into the top and it falls in to the pipe below - each equipped with a screew and 36 - <STRONG><U>36</U></STRONG> pressurised axel sealings!! and 18 drive mechanisms!! The maintenance cost will far exeed the income from each line in a commercial market </FONT></DIV>
<DIV dir=ltr><FONT face=Arial>4. Tars are not easy to handle </FONT></DIV>
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<DIV dir=ltr><FONT face=Arial>Here in Denmark we have designed 2 real staged gasifiers one is the Viking and the other is the TKE 3 stage gasifier. </FONT></DIV>
<DIV dir=ltr><FONT face=Arial>The Viking has a screew pyrolyser very similar to the one that Range use. The TKE gasifier uses an internally heated plug pyrolyser. The reason the I went a way from the Screew pyrolyser was that i could </FONT></DIV>
<DIV dir=ltr><FONT face=Arial>1. Not see how upscale it</FONT></DIV>
<DIV dir=ltr><FONT face=Arial>2. Not see hw to make a safety approval </FONT></DIV>
<DIV dir=ltr><FONT face=Arial>3. See too high maintenance costs </FONT></DIV>
<DIV dir=ltr><FONT face=Arial>But for both gasifiers electricity made from biomass cost s around 50-75 cent US pr kWh in a 3-800 KW gasifier. </FONT></DIV>
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<DIV dir=ltr>The answer to your last question is -- YES</DIV>
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<DIV dir=ltr>Best regards</DIV>
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<DIV dir=ltr>Thomas Koch </DIV>
<DIV dir=ltr><A href="http://www.tke.dk">www.tke.dk</A> </DIV>
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<FONT size=2 face=Tahoma><B>Fra:</B> gasification-bounces@lists.bioenergylists.org på vegne af andrew schofield<BR><B>Sendt:</B> on 26-01-2011 05:25<BR><B>Til:</B> gasification@lists.bioenergylists.org<BR><B>Emne:</B> Re: [Gasification] Range Fuels Closing Plant<BR></FONT><BR></DIV>
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Dear Thomas Koch,<BR><BR> How much of a problem for the scaled up Range Fuels plant, was heat transfer from the hot fluid outside the auger-tubes to the celluose inside each parallel screw-tube?<BR>we gather a hint of the problem from your description, and Range Fuels needing to consult you about your experience with <BR>hot-fluid jacketed screw-pyrolizers.<BR><BR> Dr Reed said he saw the liquid fuel process working at small scale. May I guess this success was with a jacketed single-screw?<BR><BR> Inside the radiation, and convection sections of water-tube boilers steel surface temperatures can vary widely, as water vigorously circulates inside. <BR>Water, being more fluid than wood chips screwing along in a tube, keeps steel temperature within certain limits throughout the entire boiler setting. <BR>May we use this analogy to describe one problem experienced with Range Fuels attempt at system scale up?<BR><BR>A culinary anology for heat-jacketed auger-tubes is stir-frying vegitables in a Chinese wok. The chef adroitly presents new surfaces of the food to the hot steel to transfer heat by conduction. The chef can only make a batch of food under a certain size. Size beyond which he may choose to use a pressure cooker which can feed an army.<BR><BR>Would not direct-contact heat exchange between the hot fluid, and the wood be more practical at 4 ton/hr?<BR><BR>Andrew Schofield<BR>Renewable Fuel Systems<BR><BR><BR>Thomas Koch wrote:<BR> Tom<BR> <BR> Range fuel gasification technology was an externally heated<BR> pressuries pipe with a transport screew inside when I saw it. <BR> It was very similar to the pyrolysis unit on the wiking gasifier but<BR> they had ideas to upscale it to 4 tons pr hour by stacking pipes with<BR> screew conveyers. Thinking of the challenges of making the 1 tons pr<BR> hour screew pyrolyser in Haslev i have doubts this principle will<BR> ever be competitive for energy production - even for atmospherich<BR> applications. Thomas Koch <BR><BR><PRE>From: Thomas Reed <tombreed2010@gmail.com><BR><BR> I attended a few of the formative meetings of Range Fuels back about 2007 when I lived in Denver. <BR>I have known Bud Klepper since about 1988 when we worked together on a methanol project. <BR>Too bad that many $millions couldn't solve at a large scale what Bud had solved at a small scale. <BR> <BR>Tom Reed, Pyrologist<BR> </PRE><BR>Jim of All Power Labs wrote:<BR> thomas, why did you think a stacked array of skinny auger retorts won't work? this seems a known solution that tends to work as far as i know. of course the proof is in the material handling with specific fuels.<BR><BR> did you find it difficult to keep the auger straight and working? difficult to keep the heat out of the motor and bearings at the ends?<BR><BR> any secret cautionary tales we should know of?<BR><BR> jim<BR><BR></DIV></BODY></HTML>