Browsing by Author "Direito, D."
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Pyrolysis of cork residues - preliminary resultsPublication . Teixeira, J; Direito, D.; Crispim, A.; Ribeiro, A. M.; Silva, L. M. S.The energy from renewable sources is a topic that has been widely discussed and studied, especially since the use of fossil fuels in industrial processes are the principal source of environmental pollution. ln, this context, the processes of biomass gasification and pyrolysis are alternatives for energy enhancement, especially in rural areas [1]. One novel area that has begun to be investigated is the use of cork residues. Gasification studies have been conducted using several) samples of residues obtained during different phases of the cork manufacturing process in order to test their ability to produce energy [2]. An alternative to gasification is pyrolysis, which involves the carbonization of solid materials in an inert atmosphere, resulting in three distinct products: gas, oil and a carbon-rich solid residue. The formation of pyrolytic products is influenced by the operating conditions and the characteristics of the raw material [3]. The aim of this study was to investigate possible innovation in the cork industry by analysing the efficiency of pyrolysis of natural cork waste and by identifying optimal operating conditions, and the characteristics of the products obtained. ln, this paper some preliminary results are reported
- Pyrolysis of leather wastes from the footwear industry –preliminary resultsPublication . Direito, D.; Pilão, Rosa Maria; Crispim, Alfredo; Ribeiro, A.M.Most of the leather used by the footwear industry (more than 70%) is produced from skins and hides tanned with chromium sulphate [1]. The production of leather goods, especially shoes, gives rise to wastes that amount to 15 – 20% of the entry leather [2]. As an example, the European footwear industry generates between 1x105 to 2x105 tons per year of leather wastes [1]. In the last few years, various investigations have been carried out in order to find alternatives to the disposal of these residues in landfills. Several processes have been developed to treat the leather residues that include, among others, combustion, pyrolysis, chemical treatment (oxidation and hydrolysis) or direct application of the wastes [2]. Pyrolysis is the thermal degradation of wastes, in the presence of an inert atmosphere, producing a solid phase (biochar), a liquid phase (bio-oil) and a gas phase composed mainly of CO2, CO, CH4 and H2 [3]. Several authors have reported work on the pyrolysis of chromium tanned leather wastes [4, 5, 6]. [...]
- Slow pyrolysis of oil palm mesocarp fibres: Effect of operating temperaturePublication . Almeida, A. F.; Direito, D.; Pilão, Rosa Maria; Mayer, B.This study investigated the effect of temperature on the slow pyrolysis of oil palm mesocarp fibres. The biomass was characterized in terms of proximate and ultimate analysis, and its higher heating value (HHV) was 18.51 MJ/kg. For pyrolysis temperatures from 469 to 783°C, at a heating rate of 20°C/min, bio-char yield varied between 32.7% and 25.8%. Gas and liquid phases were analysed by gas chromatography and Fourier-Transform Infrared Spectrometry (FTIR), respectively. CO2 was the major gas produced for all temperatures (6.9 to 10.0mol/kg of biomass) and H2 concentration increased rapidly as the temperature rose (0.6 to 8.0 mol/kg of biomass). FTIR measurements show that the bio-oils contained alcohols, phenols, alkanes, alkenes, carboxylic acids, aldehydes and aromatic compounds. The HHV of both bio-chars (27.50 to 28.86 MJ/kg) and bio-oils (25.95 to 28.50 MJ/kg) were measured. Thermal decomposition of the fibres was also studied using thermogravimetric analysis.
- Valorisation of leather wastes from footwear industry via pyrolysis: Product yields and characterisationPublication . Silva, F.; Direito, D.; Pilão, R.; Ribeiro, A.M.(Objectives) The influence of temperature on the pyrolysis of leather trimmings from the footwear industry; Characterization of leather waste used in the pyrolysis process; The physical-chemical characterizations of biochar, bio-oil and non-condensable gases.
- Valorisation of Leather Wastes from the Footwear Industry via Pyrolysis: Product Yields and CharacterisationPublication . Silva, F.; Direito, D.; Pilão, R.; Ribeiro, A.M.; Silva, Felipe; Direito, Daniel; Pilão, Rosa Maria; Ribeiro, AlbinaThe footwear industry, although contributing positively to the Portuguese economy, generates a lot of residues including chromium tanned leather wastes. This study presents results on the slow pyrolysis of these residues at particle sizes between 5 and 6.3 mm and temperatures inside the reactor ranging from 444 to 875 °C. For this range of temperatures, char yield decreased from 36.2 to 28.1% and gas yield increased between 33.2 and 47.6%. The liquid phase yield was highest at 444 °C (30.6%) and then decreased to 24.3% at 875 °C. As the operating temperature increased, there was an increase in the ash content (15.8 to 21.6%) and a decrease in volatiles content (20.9–3.7%) of biochars. The higher heating values (HHV) of the chars were between 21.9 and 23.1 MJ/kg. Preliminary results show that an increase in particle size leads to a rise in char yield. The infrared analysis of the liquid phase indicated the presence of water, alcohols, phenols, carboxylic acids, alkanes, alkenes, and aromatics. The liquid phases had an average water content of 43%, densities between 1110 and 1120 kg/m3 and the HHV between 12.7 and 15.1 MJ/kg. The gases produced were analysed by gas chromatography. For 538 °C, the production of H2, CO, CH4 and CO2 was, respectively, 1.00, 0.37, 0.18 and 1.37 mol/kg of leather. At 875 °C, H2 was the most produced gas (2.74 mol/kg leather), followed by CO, CO2 and CH4 with quantities of 1.40, 1.26 and 0.42 mol/kg leather.