Technical and feasibility study of conversion of long-stick wood to charcoal in a partial combustion metal kiln

• Published in: Energy for sustainable development 2006-09, Vol.10 (3), p.17-25
• Main Authors: Saravanakumar, A., Haridasan, T.M., Bai, R. Kasturi
• Format: Article
• Language: English
• ISSN: 0973-0826
• DOI: 10.1016/S0973-0826(08)60540-2

In India, a considerable quantity of charcoal is used in urban areas for applications ranging from industrial processing to domestic cooking. Unfortunately, field information on various aspects of charcoal production, distribution and consumption is almost non-existent. In order to promote development and proper technical intervention in charcoal production and positive links with social forestry and wasteland development programmes, collection of first-hand information on charcoal markets and marketing practices would be useful. Charcoal-making practices are empirical in nature with a built-in traditional wisdom inherited from one's ancestors. Clear scientific study of the whole process with the interventions for controlling the influencing parameters is lacking. For long-term production of charcoal, using thin but long twigs and similar type of woody biomass seems to be ideal due to the possibility of producing them in wastelands and in a short time-frame. Moreover, reaction times for the batch process in an industrial kiln are typically 8 days. In this article we describe a practical method for manufacturing high-quality charcoal from biomass that realizes yields of 48-83 % on energy basis with a reaction time of about 5 hr, depending on the moisture content of the feed. An experimental study of the conversion by pyrolysis of long-stick wood to charcoal in a partial combustion kiln was conducted to understand and upgrade the process. The present study investigates the process of partial combustion in charcoal kilns. With this concept, a 250-kg capacity metal kiln was designed and constructed. For the test period of 5 hours, 250 kg of long stick wood was converted into 75 kg of charcoal. The average conversion ratio of 3:1 means that 3 kg of air-dried fuel wood is burnt to produce 1 kg of charcoal. The temperature profiles of 456-600$dG C inside the kiln help to understand the process of pyrolysis reactions to obtain charcoal in final form.