Fellow stovers, This morning, I loaded my Rim Fire iCan TLUD with 1500 grams of Vermont wood pellets. Powered with a muffin fan, it runs like a champion.
1,000 grams of 14C water in an open top can set on top of the grate boiled in 10 minutes . Old school. 520 grams of 14C water in a Swiss Volcano style unit set on top of the grate, boiled in 3:20 minutes. The boil was so vigorous that the water spilled over the top and put out the gas fire. New school. Re-lit the gas with no problem as the water merely splashed on the burner grate and never made it into the pyrolysis chamber. Not having any secondary air introduced into the pyrolysis chamber is brilliant. I wish I had thought of it. The syngas flames are still orange, but it sure works like gang busters with no holes in the burner plate. I observe that after the yellow wood gas flames vanish at the end of the run, a deep blue flame is present on top of the burner grate. This lasts for a few minutes and then it too vanishes. Even with the fan on full, the unit self extinguishes with zero smoke. With wood pellet feed stock, there is only minor ash residue. The quenching water does not turn milky. Notes: 1. After the second boiling test, I replace the open top can on the burner. It reboiled and kept boiling boiling until the feed stock as exhausted at about the 45 minute mark. Approximately 95% of the water was evaporated, as only 49 grams of water were left in the can. The water had been out all night and had stabilized to ambient temperatures. It had quite possibly not yet warmed up to the air temp of 14C. 2. The pH of the quenching water was about 7, ie neutral. Grass quenching water tests at about pH 11. 3. The resulting charcoal has an extremely clean nose and easily passes Hugh's "no soap test". 4. Wood pellets are a lot nicer to work with than grass pellets. The exhaust gasses of grass pellet pyrolysis tend to be messy. This possibly indicates that the temperature in the system is not hot enough to crack the oils and tars peculiar to grasses. 5. The Rim Fire iCan is based on the fan powered TLUD work of Prof. Bolinio, described in 2005, and subsequent work by Paul Olivier. Like their designs, no secondary air is introduced into the pyrolysis chamber. My basic departures from their designs are that 1] I use a burner plate whose diameter is slightly LESS than the diameter of the pyrolysis chamber; 2] I use no holes at all in the burner plate; 3] I use fewer and smaller primary air holes in three concentric rings. The burner plate is essentially the opposite of a concentrator ring often used in TLUDS that introduce secondary air into the pyrolysis chamber. 6. Currently I am working with a fixed speed muffin fan. Clearly, a variable speed fan will offer many advantages. I hope to have one latter this week. The design goal is a fan than can be powered by either a 9 volt battery or a small solar cell. A key goal is a free standing unit that is not grid dependent. I am working on this with a friend who is former General Dynamics engineer. If you want more details and photos, please send me a note. More as it is. Cheers from VT, Jock Jonathan P Gill Peacham, VT. [email protected] Extract CO2 from the atmosphere.
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