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Promising Performance from a New Briquette Burner by Pete Young
[top] [end]PerformanceIt has long been thought that burning densified agricultural residues as fuels eg. sawdust, rice husks and coir dust could help to meet the increasing demands for domestic energy. The ITDG International Forum on Briquetting in November 1988 revealed that few projects had succeeded in demonstrating the acceptability of residues as clean and easy burning fuels, nor the feasibility of briquetting manufacture. Those projects that were showing some signs of promise demonstrated the importance of combining good briquette burning properties with stove designs which meet users requirements and at a cost effective price.ITDG's own briquetting work has shown this to be extremely difficult to achieve. Technical developments are continuing to get user acceptability at a competitive price. IT is working on the design of briquettes in terms of configuration, density and levels of pyrolysis combined with a reduction of energy used in the briquetting process and on optimization of stove design to meet clean burning and user convenience requirements.
Work by Roland Louvel in Niger and by Samarakoon in Sri Lanka had shown that briquettes made in the form of sticks could be a substitute for wood because they could be burnt in a similar way. Control of briquetted pellets could only be achieved by frequent and regular feeding which lead to high attendance factors and low acceptability. With these problems in mind BEST Ltd (Biomass, Energy, Services and Technology Ltd) designed a stove that would burn briquettes in a stick like manner. The high degree of control over power levels is unique for such combustion devices and comparable to that of kerosene stoves.
Power levels were however on the low side and led to boiling times between 9.5 mins and 28 mins. As a result of the greater control over the rate of combustion, emmissions were remarkably low and produced no appreciable soot deposits on the cooking pots. This design of stove with its unique method of combustion is only in its early stage of development, but already it has demonstrated its potential to burn clearly and controllably with sawdust briquettes. Limited field trials are now being planned in Kenya to determine users reaction. [top] [end]Description and UseThe "Briquette Burner" stove is operated by placing a briquette into each of the 2 tubes. The ends of the briquette are pushed into the fire box and are lit from above, either with kerosene or waste paper and a few small pieces of briquette. Once the briquettes are alight the pot may be placed on the stove.The power can be increased-by pushing the briquettes in or reduced by pulling them out. As the briquettes burn away, leaving behind char this needs to be dislodged by gently rubbing the ends together while still in the stove. Combustion is very clean because the air supply enters the stove through the hole in the briquettes at the points where combustion is initiated. Long thin swirling flames evolve out of the ends of the briquette and rise to the bottom of the pot in a concentrated flame envelope. This leads to high convectional heat transfer with high view factors (surface area of pot exposed) which in turn give higher efficiencies compared to most other types of combustion chambers. [top] [end]Contents: Boiling Point 16: Muds, Clays and Metals for Stove Making
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Page created:
27 August 2008; Last edited:
02 September 2008; Version: 0 | |||||||||||
Pagename: BP16:PromisingPerformanceFromANewBriquetteBurner @HEDON: QENA | |||||||||||
