Dear Ron and Aron
A Rocket stove typically makes quite a bit of charcoal and that is one reason why you should put a grate in, if you plan to save fuel. The ends of the sticks fall off long before the charcoal is burned and sit in a pile on the floor of the combustion chamber. Whatever happens not to burn, is lost later. If you want to make additional charcoal put in a grate with a small number of 8mm holes in it, of 6mm. This will cut off most primary air and cause the creation of a much larger (about double) the amount. The Namibian Tsotso is a stove which is built exactly like that. It creates charcoal so effectively that towards the end of a WBT it hard to get additional fuel in because of the pile of char. It could in theory burn at least some of it but it is not really set up to do so. If you do add such a grate, it is, by definition, a not Rocket Stove (which always has overhanging fuel and air supplied from underneath). The Institutional Lion Stove, which is basically a Rocket Stove with preheated primary air, also makes a lot of char, until it fills the lower combustion chamber. This then acts as a simmering fuel charge and all the firewood can be removed. I have seen a stove with a 70 litre pot simmering for ages (more than an hour) using on this cube of char what was blocking the primary air entrance up level to the fuel shelf (which is made of brick). In fact I found a photo of that very stove which is at an orphan feeding station in Moneni, Swaziland. There is no firewood in the chamber at all. The stove saves about 70% of the fuel in part because of this. If you are wondering what the metal rings are on the top, the pots are chained to the stove to prevent them growing legs. They already have three feet so they tend to go walk-about. Xavier on this list has been making similar stoves in Benin. A complete description of how to make it is in the NDE library at http://www.newdawnengineering.com/website/library/Stoves/lionstove/ Regards Crispin Aron: Can you clarify your intended design? I know of no way that you can turn a rocket stove into a char-making stove (but would love to hear differently). Ron.
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