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- Co-gasification of glycerol/fat mixtures in a downflow fixed bed reactor: Preliminary resultsPublication . Almeida, A.; Pilão, Rosa Maria; Ramalho, Elisa; Ribeiro, A.M.; Pinho, CarlosThe aim of this work was to assess the technical viability of glycerol/fat co-gasification. The gasification performance was studied in a downflow fixed bed reactor using steam as oxidizing agent. Tests were performed with a mixture of 10% of fat and 52% of water, and the effect of temperature was evaluated in the 800 ºC to 950 ºC range. Samples of dry gas from the gasifier were collected and analysed by gas chromatography in order to determine the CO, CO2, CH4 and H2 content. The results revealed that the co-gasification of glycerol/fat mixtures seems to be a feasible technical option. Best results of the gasification parameters were obtained at the highest tested temperature, 950 °C.
- Influence of the operating temperature on the slow pyrolysis of pineconesPublication . Nascimento, M.; Silva, F.; Pilão, R.M.; Neto, M.P.; Ribeiro, A.M.This study investigated the production of biochars, bio-oils and non-condensable gas from pinecones through pyrolysis. The effect of temperature on the yields of the three phases and their characterization was studied. Char yield varied from 39.7 to 29.5 % and gas yield increased from 22.1 to 33.9 % as temperature rose from 408 to 661 ºC. Bio-oil yield increased from 38.3% at 408 ºC to 39.9 % at 562 ºC and then decreased to 36.6 % at 661 ºC. The chars obtained had an ash content between 1.38 and 2.20 %, volatiles in the range of 3.90 to 22.99 %, fixed carbon from 75.23 to 94.72 % and a higher heating value (HHV) in the range of 28.81 to 31.63 MJ.kg-1. The gas phase was mainly composed of carbon dioxide (CO2), carbon monoxide (CO), methane (CH4) and hydrogen (H2).
- Thermogravimetric analysis of high-density cork granules using isoconversional methodsPublication . Ribeiro, A.M.; Ramalho, Elisa; Pimenta, Maria Paula; Pilão, Rosa MariaIn the present work thermogravimetric techniques were used to study the thermal degradation of high-density cork granules. Pyrolysis experiments were carried out for four heating ramps (10, 15, 20 and 25 °C.min−1), using nitrogen as the carrier gas. From the differential thermogravimetric (DTG) curves it was seen that degradation mainly occurs from 220 °C to 525 °C for the main components of cork (suberin, lignin, cellulose, and hemicellulose). It was also observed that for temperatures higher than 525 °C and up to 900 °C, lignin continued to decompose. Activation energies were calculated using the data obtained and the two isoconversional methods Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO). For the KAS method, and for degrees of conversion between 0.10 and 0.85, the activation energies varied between 232.2 and 353.0 kJ.mol−1. Using the FWO method and for the same degrees of conversion, the activation energies were in the range of 230.0 to 346.6 kJ.mol−1. These values agree with data provided by other authors, for different lignocellulosic biomass.
- Catalytic co-gasification of glycerol/fat mixtures: A preliminary studyPublication . Cruz, A. C.; Ramalho, M.E.; Pilão, Rosa MariaIn this work, the co-gasification of treated crude glycerol and animal fat was studied using steam as the gasifying agent. Tests were performed in a downflow fixed bed reactor with a bed composed of catalyst particles of dolomite. The gasification process was studied using a mixture with 59% of glycerol, 3% of fat and 38% of water and tests were carried out at 700 ºC and 750 ºC. The producer gas was quantified and analysed by gas chromatography obtaining, for the tested temperatures, between 48% and 47% of H2, about 13% of CO, 11% of CH4 and CO2 content between 30% and 27%. The results showed that the use of dolomite as a catalyst promotes the production of a gas rich in H2 and CO2. The results also show that the gasification parameters increase with temperature having obtained at the maximum working temperature a gas production yield of 0.92 m3/kg at 750ºC, a cold gas production efficiency of 70.6% and for the carbon and hydrogen conversion efficiencies the values obtained were 58.0 % and 40.9% respectively.
- 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 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.
- Evaluation of MCP correlation algorithms applied to wind data seriesPublication . Moreira, A.; Rocha, T.; Mendonça, J.; Pilão, R.; Pinto, P.(Objectives) This work aimed to develop methodologies for analyzing statistical correlations among wind data series using various Measure-Correlate-Predict (MCP) methods, with the goal of selecting the most suitable method for extrapolating long-term data with minimal associated uncertainty. Furthermore, the study intends to investigate how the concurrent period used to build the correlation can affect the performance indicators of MCP methods.
- 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.
- Co-Gasification of Crude Glycerol/Animal Fat MixturesPublication . Almeida, Ana F.; Pilão, Rosa Maria; Ribeiro, Albina; Ramalho, Elisa; Pinho, CarlosThe aim of this work was to assess the technical viability of glycerol/fat co-gasification. The gasification performance was studied in a downflow fixed bed reactor using activated alumina particles as bed material and steam as oxidizing agent. The effect of gasification temperature, from 800 to 950 °C was studied with a feed mixture with 10% (w/w) of animal fat. The influence of fat incorporation on the feedstock in the overall gasification process was also performed, using 3% (w/w) and 5% (w/w) of fat in feed mixtures. Samples of dry gas from the gasifier were collected and analyzed by gas chromatography in order to determine the CO, CO2, CH4, and H2 content. The best results were obtained using the highest tested temperature, 950 °C, and using 3% (w/w) of animal fat in the feed mixture. The overall results revealed that the co-gasification of glycerol/animal fat mixtures seems to be a feasible technical option
- 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]. [...]