Studies of the Brazilian sugarcane bagasse carbonisation process and products properties

Laboratory-scale experiments in an enlarged scale thermoreactor have demonstrated that the pyrolysis of the bagasse bulk in a mechanically loosened layer yields 23-28% charcoal measured on an oven dry basis. The charcoal is appropriate for the production of fuel briquettes and granules for household and industry uses. To implement an energy self-sufficient production process, yields of condensable matter and gas components were determined. It is shown that their combined heat of combustion exceeds the upper limit of the heat necessary to carbonise the biomass by 1.6 to 1.8 times. To overcome the difficulties caused by a high fine particles content and the fibrous structure of bagasse, the use of a rotary drum type apparatus is suggested to be appropriate. Due to technological considerations, a two-stage process may be recommended: a heating up and pyrolysis stage up to 350 degrees C, and a charcoal glowing stage with the peak temperature 475-500 degrees C. Such a reactor unit with a joint furnace and closed pyroligneous vapour and heat carrier flow system, greatly reduces the emission of carbon monoxide (CO) and dust particles. Bagasse can be used as an alternative source of traditional wood for charcoal production. It could prevent the deforestation of native forests. (C) 1999 Elsevier Science Ltd. All rights reserved.