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- Energy and exergy analysis of co-gasification of crude glycerol and animal fat mixturesPublication . Almeida, Ana; Pilão, Rosa Maria; Ramalho, Elisa; Pinho, CarlosThis work presents an energy and exergy analysis of co-gasification tests of crude glycerol and animal fat mixtures, in order to obtain first and second law efficiencies, the last ones representing a novelty in the field of gasification technology. Mixtures with 5% (w/w) of dry animal fat, 57% (w/w) of dry treated crude glycerol and 38% (w/w) of water were studied in a fixed bed down flow gasification reactor at 800°C and 900°C. The increase of gasification temperature seems not to affect the energy and exergy yields of the overall process.
- Effect of catalyst on the producer gas composition from co-gasification of glycerol/fat mixturesPublication . Cruz, Amaro; Ramalho, Elisa; Ribeiro, Albina; Pilão, Rosa MariaIn this work, steam reforming of crude glycerol and animal fat mixtures was studied. The tests were carried out at temperatures of 700 °C and 750 °C in a fixed bed reactor using activated alumina or dolomite particles, to evaluate the catalytic capacity of these minerals in the removal of tar from the producer gas. The gas produced was quantified and analyzed by gas chromatography, and it was concluded that its composition is greatly influenced by the bed material used. The results obtained showed that dolomite is more effective in reducing the tar content, evidencing its ability to catalyze the tar reform reactions and promoting the water-gas shift reaction. Consequently, using dolomite as a catalyst, a producer gas with 47–48 vol% in H and 27–30 vol% in CO2 was obtained, while using a bed of alumina particles, a gas with a high CO content (45–48 vol%) and lower H content (34–37 vol%) was produced.
- Catalytic co-gasification of glycerol/fat mixtures: experimental vs thermodynamic equilibrium resultsPublication . Cruz, A. C.; Ramalho, Elisa; Pilão, Rosa MariaIn this work, the co-gasification of treated crude glycerol and animal fat was studied using steam as the gasification 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 °C and 750 °C. The producer gas was quantified and analyzed 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. Maximum values of 0.92 m3/kg for dry gas yield, 70.6% for cold gas efficiency, and 58% and 40.9% for carbon and hydrogens efficiencies were obtained. The gasification process was evaluated using the non-stoichiometric chemical equilibrium model. The results obtained showed that the real gasification process does not reach chemical equilibrium.
- 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.
- 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