Balanço energético do processamento mecânico de toras de eucalyptus

Abstract

In sawmills, the band and circular saw are the main machines wich consuming energy in the sawing of logs. In addition to producing lumber, during the sawing it is also generated large amounts of waste. Eventually, this waste can be burned for energy or used for making other items. The wood when compared to other materials such as steel, concrete, aluminum, ceramic, plastic, presents among other advantages high energy efficiency. The main objective of this work were to evaluate the efficiency of the energy balance of the sawing of logs and the influence of the log properties in the energy consumption of the saws. This work used ten logs of Eucalyptus grandis plantation with 15 years of age, cut from an area of the Federal University of Lavras (UFLA). The logs were sawn using a band saw and then the boards were re-sawn in a circular saw. The consumed electrical energy was measured using a multifunctional meter. The energy stored both in the waste and in sawn wood was determined by the lower calorific value. The energy balance was calculated as the difference between the consumed electricity in the saws and the energy stored in the waste and sawn wood. The consumption of electrical energy to produce one cubic meter of sawn wood was equivalent to 201.28 kWh. The balance of energy that considers the energy stored in the waste and sawn wood was 2.2 times higher than the balance that considered only the energy from waste. The mass was the property of the log that most influenced the intensity of consumed energy in the cuts (R ² = 0.61). The results also showed that the production of sawn timber of Eucalyptus grandis has the potential to be self-sufficient in electricity.