Dear Ronald >Dear Jeff, >I'm wondering a bit what you mean-- if you turn the stove 90° on an axis you'd have a side load >horizontal draft-- I'm not just playing semantic tricks here: the chief gain in the TLUD is the even >distribution of natural airflow optimized for the whole of the pyrolysis plane.
Ah...but not quite so fast. What the end-lit cross draft (hereinafter ELCD) burners do is to create an angled plane that accomplishes what the TLUD does vertically. There is actually nothing involving gravity with the TLUD, almost. A TLUD can be run upside down (BLDD) so why not on its side? The essential provision is that it be done in a box, preferably a non-leaky one. Apart from the low ignition emissions, the major advantage is that it can be refuelled. It works because the air control is maintained, though with quite different materials and flow paths from a regular sheet metal TLUD. The Mongolian requirement is for a stove that will last 10 years with user maintenance. It should be in the 7-13 kW range. It must be refuellable and burn wet lignite (a form of young, brown coal). We are reproducing the TLUD effectiveness without going to the extreme of trying to leave the char unburned. It surprises me that there seems to be general acceptance that the cleanliness of a TLUD is to do with the fact they are char producing. This is simply no so. It is clean because the combustion conditions are right for the portion of the fuel that is burning burned (the volatiles). As Dean has pointed out, changing the air supply at the end can burn the char if you want. John Davies does exactly the same thing burning coal in a packed bed gasifier: first devolatilisation then coke burning, but he is also burning it vertically. What the ELCD stove does is to create a set of burning conditions that modify themselves, so to speak, creating the right conditions for TLUD wood ignition followed by the different conditions for continuous and complete burning of the coal. Once the wood is lit, the small chips of coal around it fall over the wood and are quickly lit. This also opens a hole in the 'floor' of the fire meaning an air entrance near the outlet of the combustion chamber which is the entrance of the pipe in which the smoke is burned by the flames. The hole provides enough air to change the ratio of primary to secondary and maintain a pretty clean burn. It is not a classic TLUD vertical profile, obviously, but as the air drafts sideways from the loading door through the coal to the pipe at the opposite end, it creates the same result: evaporated volatiles, evaporated moisture, and CO. As there is a bowl-shaped fire burning near the pipe, the combustibles are dealt with immediately or in the pipe. Again, please make no assumptions, everyone, that the low PM from TLUD's is the result of not burning the carbon. The ELCD probably has lower PM than anything tested so far (based on the numbers we have heard from Aprovecho tests) and it definitely burns the carbon. If you think of 1500 mg of PM 2.5 being considered as an emissions standard for about 15 MJ of heating power, that is 100 mg/MJ. The GTZ 7.5 has been run twice in the past few days with quite casual ignition, with a total of less than 0.5 mg/MJ over a 5 hour run. Merely reversing the ignition position to the fuel door end increases emissions to about 300 mg/MJ. (By the way the GTZ 7.5 is not an ELCD stove. It has a hopper.) So I conclude that it is quite possible to run a TLUD on its side and thus overcome the primary problem of not being able to refuel one. >regards, >Ronald von derbesinnlichenweihnachtsstimmung Materialistisch Weihnachtsgrüße ... Crispin _______________________________________________ Stoves mailing list to Send a Message to the list, use the email address Stoves mailing list 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/ [email protected] http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
