Otto Formo said "Fuel efficiency and clean burning, are more or less linked together."
Yes indeed! It helps to realize that smoke is fuel in its own right. For some fuels, the smoke has a higher heat energy content (MJ/kg) than the fuel itself, which means that if you have an inefficient stove that produces smoke, the fuel left behind once the smoke has been driven off actually has less energy than the fuel you started with. Start clean and then add a chimney. If you can get quite a clean burn with a natural draft, then adding a chimney should improve the burn further because of the added draft. Only then will your chimney remain clean for years. Many cheap chimneys are thin galvanized metal. Starting and stopping the fire causes some condensation, and residual NOx and SOx then give rise to rapid corrosion. So the best chimneys are brick or clay, with relatively thick metal a good alternative. And yes, even biomass can give SOx. Always check the possible size of chimneys in the field. I once tested a fuel in a lab stove that had a 3m chimney, and it worked really well. The same fuel in the same stove in the field was a total failure because the maximum chimney was about 1.5m. The first cancer directly linked to human activities was a scrotal cancer in Victorian chimney sweeps, who had to climb up the huge chimneys with brooms to keep them clean. If the soot was allowed to build up, it could eventually catch alight and burn the house down. Prof Philip Lloyd Energy Institute Cape Peninsula University of Technology PO Box 652, Cape Town 8000 Tel:021 460 4216 Fax:021 460 3828 Cell: 083 441 5247 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: 09 February 2012 03:07 To: [email protected] Subject: Stoves Digest, Vol 18, Issue 10 Send Stoves mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists .org or, via email, send a message with subject or body 'help' to [email protected] You can reach the person managing the list at [email protected] When replying, please edit your Subject line so it is more specific than "Re: Contents of Stoves digest..." Today's Topics: 1. Re: Grates and chimneys (Otto Formo) 2. Re: Grates and chimneys (Xavier Brandao) 3. Re: Grates and chimneys (Fireside Hearth) ---------------------------------------------------------------------- Message: 1 Date: Wed, 8 Feb 2012 19:06:52 +0100 (MET) From: Otto Formo <[email protected]> To: "Paul S. Anderson" <[email protected]>, Discussion of biomass cooking stoves <[email protected]>, Otto Formo <[email protected]> Cc: [email protected] Subject: Re: [Stoves] Grates and chimneys Message-ID: <[email protected]> Content-Type: text/plain; charset="iso-8859-1" Dear all, Yes, nobody should clog their chimneys. On the other hand, nobody should belive that stoves with chimneys are clean burning, any how. A chimney will "only" make sure that we will have no more indoor polution, while outdoor polution in larger cities are a huge problem, related to insufficient combustion. According to Paal, top lit fireplaces ,will have a very positive effect on outdoor polution too. Fuel efficiency and clean burning, are more or less linked together. If you aim for a "very" clean burning stove, you will most likely have a fuel efficient stove, as well. On the other hand, you have no "guarantee", that a fuel efficient stove are "very" clean burning. Focusing on the new ISO standard Workshop for Clean burning and Efficient Cookstoves in Holland at the end of this month, we should stress on the clean burn in stoves and not so much at efficiency. CO and PM are the most important issues, when it comes to indoor polution. Otto Still a TLUD ND gasifier fan.......without a fan..... _______________________________________________ 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/
