Alex and list See below.
----- Original Message ----- From: "Alex English" <[email protected]> To: "Discussion of biomass cooking stoves" <[email protected]> Sent: Wednesday, January 25, 2012 4:59:09 AM Subject: Re: [Stoves] The upside of Down feed Ron, On 24/01/2012 12:35 PM, [email protected] wrote: Alex and list: R: This is to further explore the idea of char production in your device (which we should call??). A: We could call it the thinking-outside-the-box-stove stove:) Suggestions? <blockquote> [RWL2a: Obvious - Im going to use "Alexifier". </blockquote> <blockquote> After writing this, I started a too-long, not yet well-thought-out naming exercise based on ideas like "TLUD". I have been wanting to add a label on whether a pyro-device has a fixed/stationary pyrolysis front/zone (yours) - or a moving one or no single pyrolysis front (a retort or a TLOD). Might also want to identify natural or forced draft, etc. After some more thought I'll post something that might lead to a more generic name than "Alexifier". </blockquote> R: In the exchange below, I think I have to side with Crispin - is not the fuel essentially all combusted? Of course it is the usual two-step combustion - with pyrolysis first leaving a pile of char - which is then itself more slowly combusted? As the char disappears, more pellets are able to fall down. You seem to have established stable rates of pellet and air flows such that the pyrolysis zone is unable to travel up into the hopper. <blockquote> </blockquote> A: A combination of forces are moving the pellets down and over while they burn, completely. [RWL2b - Except for your longish "Kilimanjaro mound", noted last, which remains pyrolyzed, not combusted] <blockquote> R: The Venturi effect you mentioned is one drawing both pellets and air down from the hopper - yes? (When I wrote yesterday I was fixated on char movement.) </blockquote> A: No, the venturi is the shape of pile at the end of the grate. It is not a functioning venturi. The chimney effect draws the air. [RWL2c: I am slowly getting the picture. <blockquote> R: My reason for still pursuing the char production possibility is that your geometry seems very similar to the Dasifier (concept of Agua Das - being ccd). Das tells me he can produce char. Somehow your grate has to be replaced by one that allows char to fall through?? Is there any alternative then to an auger? </blockquote> A: Air and gravity may be able to move the char enough to create a continuous flow. As the pellets lighten during charring they are more subject to the force of moving gasses. A bit f a long shot, but possible. <blockquote> [RWL2d: I failed earlier to comment on the slanted grate - which looks to be important. The weight change ito the Kilimanjaro mound s presumably about 75%. Your comments here indicate char capture may be pretty limited. But maybe even a little capture would help keep emissions down and overall fuels costs lower. I am afraid that a lower auger may be the device needed to obtain much char. . </blockquote> <blockquote> R: Might it make sense to replace the tall chimney in some circumstances with a blower? (To lower first costs - allowing a much shorter chimney?) </blockquote> A: Yes. <blockquote> [RWL2e: The best part of a blower (what location(s) would you recommend?) from my standpoint is the ability to have cheap power level control . But here there would also seem to be a major initial cost advantage (using fans/blowers out of dead computers). Andrew Heggie once gave me a $1-$2 pulse width controller built by a friend of his. ] </blockquote> <blockquote> R: Is this development related at all to backup heating of your greenhouse? Or manly intended for home heating? Any applicability to cooking? </blockquote> A: No this is pure science:) My first choice is to succeed with wood chips as they are cheap and available and cordwood and chainsaws has taken a toll on my old tendons and ligaments. Combustion processes are adaptable to local needs and circumstances. I won't predict how they will be used. I used Tom's TLUD camp stove to heat phosphoric acid to clean a copper heat exchanger at the greenhouse last fall. It was perfect for the job. Who'd a thunk. [RWL2f. Addressing those who don't know Alex - he is one of the best "pure" scientific types on this list (which he won't admit). But he is more. He displayed genius in converting a large greenhouse moving grate boiler to one that pyrolyzes - improving emissions as well. Probably/hopefully going to make money eventually on the produced char, when he feels more comfortable with what he has. His emphasis on chips is possibly appropriate for all small cookstoves - maybe drop operating costs by a factor of 3 or more over pellets. Alex - I had one more thought on your "pot" idea to collect char. How about if this pot is below a right angle bend in your horzontal air-fuel line? The idea would be like a cyclone: particles (charred pellets or pellet particles) would bump into the wall and drop into your "pot". A ways back you talked about chips acting like "sails". Maybe that could be helpful rather than harmful - and this proposed right angle bend (suitably located "downwind" from the hopper) could catch them. A glowing particle entering the "pot" would presumably extinguish fairly quickly as air entry would be prevented by some still remaining combustible gases exiting upward - out of this "pseudo-retort" .. Another thought - several bends and pots - where there might be some size and shape separation.. One directly under the hopper might catch pellets that have dropped sufficiently in size (forced through also by weight above? (All this trying to avoid the cost of an auger) . Maybe my above comments all worthless, but thanks for sharing this new scientific exploration idea with us. Many ideas to explore. Ron Alex Ron <blockquote> [email protected] To: "Discussion of biomass cooking stoves" <[email protected]> , "Alex English" <[email protected]> Sent: Monday, January 23, 2012 9:38:55 PM Subject: Re: [Stoves] The upside of Down feed Alex and list: My interest is in the first several lines, which read: Crispin: "This is interesting news. The grate looks great, and if there is a pile of char that is maintained in front, we must conspire to burn it." Alex: "Not so fast. I rather like the idea of a naturally formed biochar venturi:)" RWL: I have totally missed the possibility of a char output in your design. I can't even see a Venturi possibility.. Can you explain a bit more on how that can be accomplished? Have you accomplished any char preservation yet? Thanks. Ron ----- Original Message ----- From: "Alex English" <[email protected]> To: "Discussion of biomass cooking stoves" <[email protected]> Sent: Monday, January 23, 2012 6:45:36 PM Subject: Re: [Stoves] The upside of Down feed Dear Crispin, On 22/01/2012 10:36 PM, Crispin Pemberton-Pigott wrote: <blockquote> Dear Alex This is interesting news. The grate looks great, and if there is a pile of char that is maintained in front, we must conspire to burn it. </blockquote> Not so fast. I rather like the idea of a naturally formed biochar venturi:) <blockquote> <snip remainder> </blockquote> </blockquote> _______________________________________________ Stoves mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://www.bioenergylists.org/
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