Balanço de massa e energia na pirólise da madeira de Eucalyptus em escala macro

Abstract

Industrial technologies currently employed in the carbonization of wood are inefficient, generating in addition to charcoal, over 70% of co-products with high energy potential, but still without proper use. This way, it is necessary to develop tools that seek to better understand the phenomena that control this process, in close range to industrial. Before that, the objective of this study was to evaluate the effect of moisture and diameter on mass and energy balance in Eucalyptus urophylla wood small logs in the pyrolysis process in laboratory scale simulating the industrial process. Two trees were collected and used two short logs 30 cm per tree, with a diameter of 7 cm and 12 cm. Later they were stored in greenhouse and outdoors for drying. Initially we sought to characteriz e the wood from chemical, energy and physical analysis. The carbonization were performed in an electric kiln called Macro ATG at the final temperature of 500 °C and a heating rate of 5 °C min -1 . They were evaluated in charcoal chemical composition, immediate, energy and physical. The flux, mass and energy potential of non condensable gases were estimated from data provided by the oven software. There were also mass and energy balance of the process. The wood moisture in the stove was 0.58 and 0.83% respectively, the diameters of 7 cm and 12 cm, while the dried woods outdoors for both classes diametric humidity was 13%. Low coefficients of variation were found between the diameter classes both in the characterization of wood and the charcoal. The moisture and did not affect the mass and energy balance of the process, however influenced the production and quality of the gas. The more energetic gases were produced from the raw material dry and diameters influence the thermal gradient from the heating rate. There is a large variation in temperature in the wood during carbonization due to heat transfer, the difference between the area-center can reach up to 120 ° C. The heating rate decreases with increasing temperature. The peak gas production is the same as the maximum energy production starts 120 minutes after the pyrolysis and has a maximum duration of 30 minutes, possibly the best moment of firing. During this interval, the temperature in the timber is above 300 °C.