Tom et al Any cite for the 5-7% value?
Your last sentence is confusing to me with the word "gasifying pyrolysis gases" in it. Paul is striving for only pyrolysis, and don't think he is proposing a packed charcoal bed. Ron On Apr 28, 2013, at 2:19 PM, "Tom Miles" <[email protected]> wrote: > Paul, > > > > It’s a great idea to use char as a filler but there is a cost. I am sure > that you will find that a small percentage of the charcoal “filler” will be > consumed as charcoal will burn in direct contact with air or through > reduction of the char. You will always have a little excess air or moisture > in the bed. When charcoal is used as a packed bed for gasifying pyrolysis > gases charcoal consumption is estimated at 5-7%. > > > > Tom > > > > > From: Stoves [mailto:[email protected]] On Behalf Of Ron > Sent: Sunday, April 28, 2013 1:08 PM > To: [email protected]; Paul Anderson > Cc: [email protected]; Eckhardt, Bradley D; Discussion of biomass > cooking stoves > Subject: Re: [Stoves] [biochar] TLUD advances -- Two more uses of char > > > > Paul et al > > > > This is to recognize and applaud the "char filler" suggestion you received > from NASA's Dr. Jack Bacon. I like it and hope we can hear soon from some > who may have tried it. My guess is that there is some maximum char volume > above which Andrew's observation today of char combustion will prevail. > > > > You correctly talked of the pyrolysis front. Equally, users should be > thinking about char combustion if any char particle gets hot enough while the > upward flowing primary air still contains O2. Upflowing primary air can > get to char easier than fuel since there will be no/little exiting gases from > the char. > > > > Good note. > > > > Ron > > > > > On Apr 28, 2013, at 10:01 AM, Paul Anderson <[email protected]> wrote: > > > > Dear all, > > These two and many other "tips" need to be collected and told to TLUD > stove users. One avenue is in Christa's Manual, Another is in stove > manuals and at training sessions. And at websites, etc. > > 1. Charcoal to extinguish hot charcoal: When dealing with small > amounts of hot charcoal as in the residential TLUD stoves, one easy way > to extinguish hot charcoal is to dump it into a somewhat larger amount > of already extinguished (cold) char. The cold char takes up much of > the heat, extinguishing the hot char. Be sure that it is well mixed > and sufficiently cooled to avoid re-ignition. This is best done in > containers that can be sealed. Containers of metal or ceramic are > best, but even wood could be used if the quantity of cold char is > sufficient to prevent the hot char from reaching the sides. As always, > be careful because oxygen to a small hot ember can lead to much greater > combustion. > > 2. "Space fillers" in loose fuels in TLUD devices: > > General note about fuel in TLUDs: > In general, dry biomass fuels in TLUDs need to appropriately fill most > of the air-space in the fuel chamber. This is accomplished with > smallish pieces such as wood chips, pellets, short-cut twigs, and shells > of seeds. Also, careful packing with vertical wood-segments or > straight-ish reeds can occupy the space. But twisted sticks and > long-ish pieces that bridge inside the fuel chamber leave too much space > unoccupied. In those cases, the space can be appropriately occupied by > adding small pieces, as named above. Shake the TLUD to assure that the > pieces have settled in well, and add more as needed. These fillers > will also pyrolyze and become charcoal. > > Inert materials as "space fillers": Technically, the space fillers > could be inert materials such as ball bearings or pebbles (of rock that > will not shatter with this heat) or fired clay balls. Although they > could function effectively, they would require separation after the > batch is unloaded and cooled. But there is one material that solves > these inconveniences and costs. It is charcoal. > > Charcoal as a space filler: TLUD stoves make charcoal. Therefore, > charcoal is not a fuel for TLUD stoves. However, small pieces of > charcoal (but not charcoal fines) can also be used as "space fillers" to > solve the need to restrict air flow in the fuel chamber. The char will > not pyrolyze and will not burn (char-gasify or oxidize) as the pyrolysis > front moves downward through that biomass fuel. > > a. Char is abundant for TLUD users, and at no additional cost, and is > not consumed. > > b. Unlike small pieces of biomass as fillers, char pieces cannot catch > on fire and then fall down to the lower areas of the fuel chamber and > igniting fire there. > > Charcoal as a reducer of thermal output: Clearly in the above > statements when charcoal is used as a space filler, the fuel chamber > contains less biomass and therefore less heat will be generated (which > is desirable for simmering and some other cooking needs). > > Another variation is to have well packed (mainly straight) wood or reeds > or stems as a vertical bundle in the middle of a TLUD fuel chamber. > Then load in small charcoal all around the bundle to fill in the > remaining space. When used (pyrolyzed), the fuel will yield heat in > proportion to its cross-sectional area of the fuel bundle, not of the > entire cross-sectional area of the fuel cylinder. This is because the > annulus of char is essentially non-combustible at the pyrolytic > temperatures in the TLUD reactor. > > Variations of all of the above need to be tested and even measured. > (This will be utilized at the Stove Camp at Aprovecho 22 - 26 July 2013). > > Note: Credit for much of the above goes to Dr. Jack Bacon, a senior > scientist at the NASA Johnson Space Center in Houston, TX. Jack, a > leader in the local chapter of Engineers Without Borders (EWB-JSC), > suggested charcoal as fillers during discussions in April 2013 with Paul > Anderson about an EWB project to use TLUDs for heat in a fruit dryer in > Rwanda. > > Dr TLUD > > -- > Paul S. Anderson, PhD aka "Dr TLUD" > Email: [email protected] Skype: paultlud Phone: +1-309-452-7072 > Website: www.drtlud.com > > > __._,_.___ > Reply via web post Reply to sender Reply to group Start a New > Topic Messages in this topic (3) > RECENT ACTIVITY: New Members 4 > Visit Your Group > MARKETPLACE > > > > Switch to: Text-Only, Daily Digest • Unsubscribe • Terms of Use • Send us > Feedback > . > > __,_._,___
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