Proceedings of COBEM 2005 18th International Congress of Mechanical Engineering Copyright © 2005 by ABCM November 6-11, 2005, Ouro Preto, MG THE INFLUENCE OF CARBONIZATION TEMPERATURE AND CARBONIZATION HEATING RATE IN THE CHARCOAL PRODUCTION Paulo Cesar da Costa PINHEIRO Departamento de Engenharia Mecânica da UFMG Av. Antônio Carlos 6627, 31270-901 Belo Horizonte, MG e-mail: pinheiro@netuno.lcc.ufmg.br, pinheiro@demec.ufmg.br Omar SÉYE Centro de Desenvolvimento Energético Amazônico Av. Gen. Rodrigo Octavio Jordão Ramos, 3000, 69077-000 Manaus, AM e-mail: omar_seye@hotmail.com, seye62omar@yahoo.com Francisco José FIGUEIREDO Dept. Ciências Térmicas e dos Fluidos UFSJ Praça Frei Orlando, 170, 36300-000 São João del Rei, MG e-mail: fjf@ufsj.edu.br Abstract. The biomass heated over 200°C, in absence of air has a thermal decomposition (carbonization), generating gases, vapor and a solid residue (charcoal). Many factors influence the charcoal production: chemical-physical properties, size and form of the wood, water content, heating rate, external pressure, etc. Normally the carbonization is performed in the range 400-500°C, and the process temperature has high influence on the quality and quantity of charcoal produced. The present paper shows the analysis of the influence of carbonization heating rate on the properties of eucalyptus charcoal. The tests has been carried out in a macrotermobalance, under autogenerated atmosphere, with heating rates of 1, 2,5, 5, 10, 20 and 50°C/min and carbonization final temperature of 500°C. Keywords: charcoal, biomass, eucalyptus , chemical kinetics, carbonization temperature 1. Introduction The reduction of the fossil fuel reserves and the concern with the environment have improved the use of renewed energy sources. Brazil is the world’s greater charcoal producer and consumer (8.,66 Mton, 2003), and this charcoal is used mainly in the pig-iron and steel industries (82%, 7.1 Mton). Despite the charcoal being used since the beginning of the human civilization, the chemical kinetic and the heat and mass transfer mechanisms in the interior of the biomass during the carbonization are yet not very known. In order to improve the carbonization process efficiency, it is very important to know the carbonization process parameters and the way as they influence of the carbonization kilns performance and the produced charcoal quality. 2. Carbonization Gravimetric Efficiency In Brazil, the firewood and charcoal are usually commercialized by volume, and the carbonization process “efficiency” in industrial kilns is evaluated through the Conversion Index IC: V V = IC charcoal wood where V wood is the volume of wood input (estere) and V charcoal is the volume of charcoal output (mdc, m 3 ). Table 1. Usual Factors for Conversion of Estere to Mass and to Volume of Eucalyptus and Pinus (st, kg, m 3 ) Mass Volume Wood Estere st Product kg % st % m 3 % Eucalyptus 1 Wood Bark Total 577.6 30,4 608 95 5 100 0.87 0.13 1 87 13 100 0.61 0.09 0.7 87 13 100 Pinus 1 Wood Bark Total 545.2 34,8 580 94 6 100 0.82 0.18 1 82 18 100 0.57 0.13 0.7 82 18 100 Source: BRACELPA The estere is a brazilian measure unit of overall volume of a wood stack (height x depth x width), including the empty space between the wood logs (1 st = 1 m³ wood piled up). The measurement is made in the field with a measure