| 1. |
- Caetano de Souza, Antonio Carlos, et al.
(författare)
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A low cost & safe system of hydrogen production utilizing NaBH4 and CoO catalysis
- 2007
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Ingår i: 2nd International Congress University-Industry Cooperation (UNIDU07).
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Konferensbidrag (refereegranskat)abstract
- The objective of this study was to evaluate the hydrogen production through hydrolysisof sodium borohydride (NaBH4) utilizing catalysts containing CoO. The reactant is safe and stable(when dry) at room temperature. Few works and studies have presented results of investigationsutilizing catalysts containing cobalt; however utilizing catalysts containing CoO were not found yet.In this work simple and cheap hydrogen generation system was developed having reactions atnormal conditions of temperature and pressure. A solution containing a gravimetric composition of10% wt. NaOH, 10% wt. NaBH4 and 80% wt. H2O was utilized. The reaction was carried out atvarious times using the same catalyst to evaluate its performance. This catalyst presented highrates of hydrogen production, especially at its start-up (about 99% of the theoretical hydrogenvolume was produced) at room temperature. After start-up, e.g., when more solution was put, rateof hydrogen production decreased having its production performance also decreased. Probablythis fact occurred due to the formation of the solid phase products such as NaBO2 which might fillthe porous catalyst structure; decreasing the catalytic area. This catalyst is suggested in situationswhere high production rates are necessary such as start-up of fuel cells.
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| 2. |
- Caetano de Souza, Antonio Carlos, et al.
(författare)
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Hydrogen production through hydrolysis of NaBH4: The use of catalysts containing Pt and Pt-Ru
- 2007
-
Ingår i: 2nd International Congress University-Industry Cooperation (UNIDU07).
-
Konferensbidrag (refereegranskat)abstract
- Several works about hydrolysis of NaBH4 utilizing various catalysts (such as catalysts containing Pt or Ru) are available in the literature. Investigations involving NaBH4 has increased due to the possibility to produce hydrogen using simple and safe systems, even at room temperatures with very high efficiencies. A solution containing a gravimetric composition of 10%wt. NaOH, 10%wt. NaBH4 and 80%wt. H2O was utilized and the reaction was initiated immediately as soon as this solution was put in the chosen catalysts, in this case, catalysts containing Pt and mixtures of Pt-Ru. Catalysts containing Pt and Pt-Ru presented high yields of hydrogen after the solution being inserted in the reaction vessel several times. In this study it was found out that the rates of hydrogen production were increased with catalysts containing Pt and Pt-Ru (99 and 96% of theoretical hydrogen production respectively). The catalysts containing Pt presented higher production rate, while the catalysts containing the mixed Pt-Ru presented a quasi-linear production, e.g., stable production rate.
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| 3. |
- Coronado, Christian Rodriguez, et al.
(författare)
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Development of a thermoeconomic methodology for optimizing biodiesel production. Part II : Manufacture exergetic cost and biodiesel production cost incorporating carbon credits, a Brazilian case study
- 2014
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 29, s. 565-572
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Forskningsöversikt (refereegranskat)abstract
- The purpose of this study is to carry on a thermoeconomic analysis at a biodiesel production plant considering the irreversibilities in each step (part I: biodiesel plant under study and functional thermoeconomic diagram [1]), making it possible to calculate the thermoeconomic cost in US$/kWh and US$/1 of the biodiesel production, and the main byproduct generated, glycerin, incorporating the credits for the CO2 that is not emitted into the atmosphere (carbon credits). Assuming a sale price for both the biodiesel and the byproduct (glycerin), the annual revenue of the total investment in a plant with a capacity of 8000 t/year of biodiesel operating at 8000 h/year was calculated. The variables that directly or indirectly influence the final thermoeconomic cost include total annual biodiesel production, hours of operation, manufacturing exergy cost, molar ratio in the transesterification reaction, reaction temperature and pressure in the process. Depending on the increase or decrease in sale prices for both biodiesel and glycerin, the payback is going to significantly increase or decrease. It is evident that, in exergy terms, the sale of glycerin is of vital importance in order to reduce the biodiesel price, getting a shorter payback period for the plant under study.
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| 4. |
- Coronado, Christian Rodriguez, et al.
(författare)
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Development of a thermoeconomic methodology for the optimization of biodiesel production-Part I : Biodiesel plant and thermoeconomic functional diagram
- 2013
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 23, s. 138-146
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Tidskriftsartikel (refereegranskat)abstract
- This work developed a methodology that uses the thermoeconomic functional diagram applied for allocating the cost of products produced by a biodiesel plant. The first part of this work discusses some definitions of exergy and thermoeconomy, with a detailed description of the biodiesel plant studied, identification of the system functions through Physical Diagram, calculation of the irreversibilities of the plant, construction of the Thermoeconomic Functional Diagram and determination of the expressions for the plant's exergetic functions. In order to calculate the exergetic increments and the physical exergy of certain flows in each step, the Chemical Engineering Simulation Software "HYSYS 3.2" was used. The equipments that have the highest irreversibilities in the plant were identified after the exergy calculation. It was also found that the lowest irreversibility in the system refers to the process with a molar ratio of 6:1 and a reaction temperature of 60 degrees C in the transesterification process. In the second part of this. work (Part II), it was calculated the thermoeconomic cost of producing biodiesel and related products, including the costs of carbon credits for the CO2 that is not released into the atmosphere, when a percentage of biodiesel is added to the petroleum diesel used by Brazil's internal diesel fleet (case study).
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| 5. |
- Endalew, Abebe K., et al.
(författare)
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Heterogeneous catalysis for biodiesel production from Jatropha curcas oil (JCO)
- 2011
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 36:5, s. 2693-2700
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Tidskriftsartikel (refereegranskat)abstract
- This work focuses on the development of heterogeneous catalysts for biodiesel production from high free fatty acid (FFA) containing Jatropha curcas oil (KO). Solid base and acid catalysts were prepared and tested for transesterification in a batch reactor under mild reaction conditions. Mixtures of solid base and acid catalysts were also tested for single-step simultaneous esterification and transesterification. More soap formation was found to be the main problem for calcium oxide (CaO) and lithium doped calcium oxide (Li-CaO) catalysts during the reaction of jatropha oil and methanol than for the rapeseed oil (RSO). CaO with Li doping showed increased conversion to biodiesel than bare CaO as a catalyst. La(2)O(3)/ZnO, La(2)O(3)/Al(2)O(3) and La(0.1)Ca(0.9)MnO(3) catalysts were also tested and among them La(2)O(3)-ZnO showed higher activity. Mixture of solid base catalysts (CaO and Li-CaO)and solid acid catalyst (Fe(2)(SO(4))(3)) were found to give complete conversion to biodiesel in a single-step simultaneous esterification and transesterification process. (C) 2011 Elsevier Ltd. All rights reserved.
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| 6. |
- Endalew, Abebe K., et al.
(författare)
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Inorganic heterogeneous catalysts for biodiesel production from vegetable oils
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 35:9, s. 3787-3809
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Forskningsöversikt (refereegranskat)abstract
- Biofuels are renewable solutions to replace the ever dwindling energy reserves and environmentally pollutant fossil liquid fuels when they are produced from low cost sustainable feedstocks. Biodiesel is mainly produced from vegetable oils or animal fats by the method of transesterification reaction using catalysts. Homogeneous catalysts are conventionally used for biodiesel production. Unfortunately, homogeneous catalysts are associated with problems which might increase the cost of production due to separation steps and emission of waste water. Inorganic heterogeneous catalysts are potentially low cost and can solve many of the problems encountered in homogeneous catalysts. Many solid acid and base inorganic catalysts have been studied for the transesterification of various vegetables oils. The work of many researchers on the development of active, tolerant to water and free fatty acids (FFA), as well as stable inorganic catalysts for biodiesel production from vegetable oils are reviewed and discussed.
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| 7. |
- Garcia-Rojas, L. M., et al.
(författare)
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Rendimiento de los productos de la descomposición térmica De la madera de eucalyptus saligna smith a diferentes alturas del fuste comercial
- 2009
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Ingår i: Revista Chapingo, Serie Ciencias Forestales y del Ambiente. - 0186-3231. ; 15:2, s. 147-154
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Tidskriftsartikel (refereegranskat)abstract
- In this work the qualitative and quantitative results of the thermal pyrolysis of Eucalyptus Saligna Smith is presented, to different heights of the commercial wooden log. The wood was collected from Pinar del Rio, Cuba. The need to use this wood like energy source in the region led to the research at laboratory scale. The used trees were 20 and 22 years old, from which 20 cm disks were cut at 25; 55 and 85 % height of the log, milled to chips and air dried. The chemical composition was determined and was carried out the previous analysis of the samples, as well as the thermal decomposition in micro scale. The study of products from the pyrolysis (coal and tar), it was made in a reactor of fixed channel. The caloric value of the biomass and its charcoal was determined. The influence of the height of the log in the product yields from the pyrolysis was studied.As significant differences was observed as for the chemical composition of the studied wood: cellulose, hemicelulose and lignine, being observed an apparent increase of the lignine percentage with the height of the tree. The previous analysis belongs together with the chemical composition of the studied biomass. A small decrease was observed in the yield of the coal and of the percentage of tars with the height of the tree, this belongs together with the variation of the chemical composition according to the height of the tree. The biggest yield of coal and caloric value was achieved at the lowest height of the tree. The contribution to gas goes increasing with the height.
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| 8. |
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| 9. |
- Grimm, Alejandro, et al.
(författare)
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Comparison of different types of biomasses for copper biosorption
- 2007
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 99:7, s. 25559-2565
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Tidskriftsartikel (refereegranskat)abstract
- Three biomass, birch wood Betula sp., marine brown alga Fucus vesiculosus, and terrestrial moss Pleurozium schreberi, have been compared as raw materials for preparation of biosorbents for removal of copper ions from diluted water solutions. Small sample doses (0.5 g/100 ml) of the biosorbents prepared from alga and moss enabled more than 90% removal of Cu(II) ions from diluted water solutions (5-20 mg/l). The sample from sawdust was less effective.A pseudo-second-order rate model properly described the experimental kinetic data for the biosorbents. The maximum sorption capacities (X,) determined from the experimental equilibrium isotherms by applying the Langmuir model showed that the alga had the best copper-binding ability (X-m = 23.4 mg/g), followed by the moss (X-m = 11.1 mg/g), and the sawdust (X-m = 4.9 mg/g). No visible damages or performance losses were detected for the alga and moss after five sorption-desorption cycles using diluted HCl as eluent.
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| 10. |
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| 11. |
- Grimm, Alejandro, et al.
(författare)
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Preliminary tests with a birch wood pellets up-draft air gasifier
- 2004
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Ingår i: International Scientific Conference of Mechanical Engineering.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden and Cuba a variety of biomass have being investigated for energyconversion through termochemical processes into solid, liquids and gaseous products. Biomass gasification in fixed bed seem to be attractive option for the conversion ofagricultural and forest residues into gases suitable for use as alternative fuel in gasengines in rural areas, heat or electricity production. This paper discusses the performance characteristics of a up - draft gasifier withBirch wood pellets. The bench scale gasifier was designed and built in the Royal Istitute of Technology, Sweden. A series of parameters, such as the gas and liquids yields, temperatures and ash yield were measured as a function of the time.
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| 12. |
- Herrera, I., et al.
(författare)
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Environmental impact assessment of decentralized generation of heat and power in Santa Clara city, Cuba
- 2013
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Ingår i: Proceedings of the 26th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2013. - : China International Conference Center for Science and Technology.
-
Konferensbidrag (refereegranskat)abstract
- In the last two centuries, population and resources consumption, including energy, have experienced a great expansion, which has led to a rapid increase in the scale of the anthropogenic impact on the environment. Some of the most visible anthropogenic impacts are those related to the use of fossil energy, since it provides about 87% of the worldwide energy demand. Fossil fuels combustion causes large emissions of atmospheric pollutants, which have been demonstrated to cause damages to a wide range of receptors, including human health, natural ecosystems, and the built environment. In Cuba fossil fuels represent roughly 89% of the total energy used, from this amount, about 4 229 thousands toe (46% of the fossil fuels consumption) are used for power generation and 2 273 thousands toe (25% of the fossil fuels consumption) are used for heat generation. An important fraction (about 25%) of the fuel devoted to generate electricity is consumed in Decentralized Power Stations (DPS), some of them located in highly populated areas, and a similar situation occurs with some heat generation facilities. These circumstances are probably the reason why air quality in several cities has become a visible problem, due to pollutant gas emissions. In this way the impacts related to these facilities require a detailed analysis; especially human health impacts due to the incremental exposure to polluting gases. This paper presents an environmental impact analysis in Santa Clara City. The study include four DPS, with a total installed power of 84 MW, and ten heat generation facilities, with a total installed capacity of 16.3 MW. With this purpose an Integrated Assessment of Energy Supply (IAES), based on the state of the art in engineering, dispersion models, air quality and epidemiology was carried out. This includes a perturbations analysis to reduce the negative impacts with low investment actions. The baseline and two other scenario scenarios were studied. It was demonstrated that northwest DPS cause the highest local impact in terms of years of life lost due to incremental air pollutants concentrations. The most affected areas were identified in the northwest and southwest of the city. It was determined a potential impacts on health reduction about 13%, and to reduce greenhouse gases emissions from heat generation facilities about 10%.
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| 13. |
- Marquez-Montesino, Francisco, et al.
(författare)
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Pyrolytic Degradation Studies of Acacia mangium wood
- 2015
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 10:1, s. 1825-1844
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Forskningsöversikt (refereegranskat)abstract
- Pyrolytic degradation of Acacia mangium wood was studied. The chemical composition of biomass, immediate and elemental analyses and calorific value for biomass and char, were determined. The standard and the derivative curve thermogravimetric analysis (TGA and DTG) were obtained. Devolatilization maximum of values between 250 +/- 20 degrees C and 380 +/- 20 degrees C were observed, with completion after 2 h, which confirms the selection of 2 hours for pyrolysis. Kinetic study was performed at different heating rates for a conversion rate from 20% to 80%. Average values of activation energy for temperature in degrees K of 228.57 kJ/mol for Biomass 1 and 199.36 kJ/mol for Biomass 2 were obtained by the isoconversion method of FWO. The lower value of activation energy for Biomass 2 was related to the possible catalytic activity of ash. The values of correlation coefficient from 0.9418 to 0.9946 for Biomass 1 and from 0.8706 to 0.9918 for Biomass 2, indicate the reliability of the first-order reaction model. The caloric values obtained were: Biomass 1 (16962 kJ/kg), Biomass 2 (16974 kJ/kg), chars from Biomass 1 (between 23731 y 26 942 kJ/kg) and gas from Biomass 1 and Biomass 2 (3858.7 and 4859.4 kJ/m(3), respectively).
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| 14. |
- Mendiburu, Andres Z., et al.
(författare)
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Thermochemical equilibrium modeling of a biomass downdraft gasifier : Constrained and unconstrained non-stoichiometric models
- 2014
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 71, s. 624-637
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this work is to develop a non-stoichiometric equilibrium model to study parameter effects in the gasification process of a feedstock in downdraft gasifiers. The non-stoichiometric equilibrium model is also known as the Gibbs free energy minimization method. Four models were developed and tested. First a pure non-stoichiometric equilibrium model called M1 was developed; then the methane content was constrained by correlating experimental data and generating the model M2. A kinetic constraint that determines the apparent gasification rate was considered for model M3 and finally the two aforementioned constraints were implemented together in model M4. Models M2 and M4 showed to be the more accurate among the four developed models with mean RMS (root mean square error) values of 1.25 each. Also the gasification of Brazilian Pinus elliottii in a downdraft gasifier with air as gasification agent was studied. The input parameters considered were: (a) equivalence ratio (0.28-035); (b) moisture content (5-20%); (c) gasification time (30-120 min) and carbon conversion efficiency (80-100%).
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| 15. |
- Minkova, V., et al.
(författare)
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Effect of water vapour and biomass nature on the yield and quality of the pyrolysis products from biomass
- 2001
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Ingår i: Fuel processing technology. - 0378-3820 .- 1873-7188. ; 70:1, s. 53-61
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Tidskriftsartikel (refereegranskat)abstract
- Slow pyrolysis/activation of biomass in a flow of steam is studied in laboratory equipment supplied with a fixed bed reactor. Forestry and agricultural residues of different origin are selected as raw materials (birch wood, olive stones, bagasse, pelletised straw and miscanthus). The final pyrolysis temperature is varied in the range 700-800 degreesC and the duration of the activation is 1 or 2 h. The effect of both the nature of the investigated biomass samples and the presence of water vapour on the quality of the pyrolysis products is in the focus of interest of this work. Column chromatography is used to characterize the liquid products. The surface area and the acid-base neutralization capacity of the solid products are determined by the adsorption capacity towards iodine and reactions with EtONa and HCl. The results are compared with those obtained in pyrolysis in inert atmosphere of nitrogen. It is shown that the presence of steam has strong effect on the yield and properties of the products. Significant part of the liquid product is found dissolved in the water phase obtained after condensation of the volatiles. The solid products obtained in the presence of steam have the properties of activated carbons.
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| 16. |
- Minkova, V., et al.
(författare)
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Thermochemical treatment of biomass in a flow of steam or in a mixture of steam and carbon dioxide
- 2000
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Ingår i: Fuel processing technology. - 0378-3820 .- 1873-7188. ; 62:1, s. 45-52
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous pyrolysis and gasification of biomass samples of different origin is performed in a flow of steam or in a mixture of steam and carbon dioxide. Wastes from birch wood, olive stones, bagasse, and pellets from straw and Miscanthus are used as feedstock. The raw materials are heated with 10 degrees C/min to 750 degrees C at atmospheric pressure and kept for a period of 2 h at this temperature, Laboratory experimental equipment with a horizontal rotating stainless steel reactor is used. The oxygen-containing functional groups in the solid products (-COOH, =CO and -OH) are determined using the method of Boehm. The results are compared with those obtained in treatment in inert atmosphere as well as with those obtained in a stationary reactor. The rotating pyrolysis reactor seems suitable for production of energy-rich gaseous products and activated carbons.
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| 17. |
- Proenza Pérez, Nestor, et al.
(författare)
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Estudio termodinámico y dimensionamiento de un gasificador downdraft para um sistema de cogeneración compacto en comunidades aisladas
- 2006
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Ingår i: Revista Ciências Exatas. - 1516-2893. ; 12:1, s. 53-62
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Tidskriftsartikel (refereegranskat)abstract
- The gasification system has been used for manyyears ago. It has demonstrated a good way for to solveenergetic problems for isolated communities. In thispaper, is studied the gasification system associated tointernal combustion engine. Are considered technicaland economical aspects for the system design forapplications in rural localities where the electricityenergy is not possible since economical and socialviewpoint. In this manner social contribution andeconomical benefits can be determinated.
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| 18. |
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| 19. |
- Silveira, Jose Luz, et al.
(författare)
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Incorporation of hydrogen production process in a sugar cane industry : Steam reforming of ethanol
- 2014
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; 71:1, s. 94-103
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Tidskriftsartikel (refereegranskat)abstract
- This work presents a technical, ecological and economic analysis of hydrogen production incorporation through ethanol steam reforming at a traditional sugarcane industry (sugar, ethanol). This proposal is reached through a reduction in the amount of fuel (bagasse) that is normally utilized to generate electricity without affecting the sugar and ethanol production processes, however. This surplus bagasse is utilized to produce steam for hydrogen production. In order to achieve this, it is calculated the available bagasse and maximum hydrogen amount and their inputs (hydrated and anhydrous ethanol). Based on the aforementioned, the investment needs are estimated, where the operation and maintenance cost, the operation period, the interest rate, and the annuity are considered. The incorporation of this new process is assessed through a comparison of this innovative plant with the traditional ones.
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| 20. |
- Silveira, Jose Luz, et al.
(författare)
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The benefits of ethanol use for hydrogen production in urban transportation
- 2009
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 13:9, s. 2525-2534
-
Forskningsöversikt (refereegranskat)abstract
- The purpose of this paper is to describe the benefits of sugar cane ethanol in Brazil, appointing the productivity of this type of fuel based on hectares of plantation, its carbon dioxide cycle and the contribution to reduce the greenhouse effect. In the following step the uses of ethanol for hydrogen production by steam reforming is analyzed and some comparison with natural gas steam reforming is performed. The sugar cane industry in Brazil, in a near future, in the hydrogen era, could be modified according to our purpose, since besides the production of sugar, and ethylic and anhydric alcohol, Brazilian sugar cane industry will also be able to produce biohydrogen. Fuel cells appear like a promising technology for energy generation. Among several technologies in the present, the PEMFC (proton exchange membrane fuel cell) is the most appropriate for vehicles application, because it combines durability, high power density, high efficiency, good response and it works at relatively low temperatures. Besides that it is easy to turn it on and off and it is able to support present vibration in vehicles. A PEMFC's problem is the need of noble catalysts like platinum. Another problem is that CO needs to be in low concentration, requiring a more clean hydrogen to avoid fuel cell deterioration. One part of this paper was developed in Stockholm, where there are some buses within the CUTE (clean urban transport for Europe) project that has been in operation with FC since January 2004. Another part was developed in Guaratingueta, Brazil. Brazil intends to start up a program of FC buses. As conclusion, this paper shows the economical analysis comparing buses moved by fuel cells using hydrogen by different kinds of production. Electrolyze with wind turbine, natural gas steam reforming and ethanol steam reforming.
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| 21. |
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| 22. |
- Suarez, J. A., et al.
(författare)
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A phenomenological energy model of biomass pyrolysis under autothermal fluidized bed conditions
- 2006
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Ingår i: Energy Sources Part a-Recovery Utilization and Environmental Effects. - : Informa UK Limited. - 1556-7036 .- 1556-7230. ; 28:8, s. 705-714
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Tidskriftsartikel (refereegranskat)abstract
- In Cuba a variety of types of biomass is being investigated for energy conversion through thermochemical processes into solid, liquid, and gas products. A continuous bench fluidized bed pyrolysis has been designed and is currently under testing. In this article, a transport model has been developed to simulate the axial temperature fields in a bench. The model and experimental results indicated that (1) two zones exist inside of the fluidization column, the dense bed where the exothermic and endothermic reactions are active, and the freeboard zone where the temperature of the pyrolysis product decreases continuously; (2) the bed temperature increases with an increase in the air factor. The predicted temperature is in quantitative agreement with experimental measurements.
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| 23. |
- Suarez, J. A., et al.
(författare)
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Autothermal fluidized bed pyrolysis of Cuban pine sawdust
- 2006
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Ingår i: Energy Sources Part a-Recovery Utilization and Environmental Effects. - : Informa UK Limited. - 1556-7036 .- 1556-7230. ; 28:8, s. 695-704
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Tidskriftsartikel (refereegranskat)abstract
- Oxidative pyrolysis of Cuban pine sawdust was investigated using an autothermal fluidized bed reactor. Biomass particles were fed continuously (8.13 Kg/h) in a bed, fluidized by air gas. Experiments were conduced at three different dimensionless air factors 1, 1.5, and 2 (defined as ratio of actual air flow rate to stoichiometric air flow rate). The various physical and chemical characteristics of the pyrolysis products acquired in these conditions were identified. The results indicated that (1) the operating temperature can be correlated with the air factor; (2) the higher air factor promotes high temperature and contributes to the secondary reactions, which lead to less liquid; (3) the physicochemical characterization of the pyrolysis products indicated that the air factor, in the range studied, does not have a notable influence in their properties; (4) the liquid and char products obtained may be a potentially valuable source of chemical feedstocks.
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| 24. |
- Tapia, Luis Carlos Félix, et al.
(författare)
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Sustainability Assessment of Hydrogen Production Techniques in Brazil : A Multi-criteria Analysis
- 2017
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Ingår i: Green Energy and Technology. - Cham : Springer Nature. ; , s. 139-173
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Current global demands for energy resources along with the continuous global population growth have created a great deal of stress among natural environments and societies in fulfilling such a need without disrupting economic and social structures. Policy- and decision-making processes hold some of the most important keys to allow safe paths for societies towards energy security and to safeguard the environment. Brazil has played a leading role in renewable energy production and use during the last few decades, thus becoming one of the world’s leading producers of sugarcane-based ethanol, and adapted policies to support renewable energy generation and use. Although it is true that Brazil has historic experience in managing renewables development and their further integration into the consumer market, there is still a lot to be done in order to drive new technologies that could reduce emissions even further, thus increasing economic stability and social welfare.
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| 25. |
- Zanzi, Rolando, 1954-
(författare)
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Pyrolysis of biomass. Rapid pyrolysis at high temperature. Slow pyrolysis for active carbon preparation.
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pyrolysis of biomass consists of heating solid biomass inthe absence of air to produce solid, liquid and gaseous fuels.In the first part of this thesis rapid pyrolysis of wood(birch) and some agricultural residues (olive waste, sugarcanebagasse and wheat straw in untreated and in pelletized form) athigh temperature (800ºC–1000ºC) is studied ina free fall reactor at pilot scale. These conditions are ofinterest for gasification in fluidized beds. Of main interestare the gas and char yields and compositions as well as thereactivity of the produced char in gasification.A higher temperature and smaller particles increase theheating rate resulting in a decreased char yield. The crackingof the hydrocarbons with an increase of the hydrogen content inthe gaseous product is favoured by a higher temperature and byusing smaller particles. Wood gives more volatiles and lesschar than straw and olive waste. The higher ash content inagricultural residues favours the charring reactions. Charsfrom olive waste and straw are more reactive in gasificationthan chars from birch because of the higher ash content. Thecomposition of the biomass influences the product distribution.Birch and bagasse give more volatiles and less char thanquebracho, straw and olive waste. Longer residence time inrapid pyrolysis increase the time for contact between tar andchar which makes the char less reactive. The secondary charproduced from tar not only covers the primary char but alsoprobably encapsulates the ash and hinders the catalytic effectof the ash. High char reactivity is favoured by conditionswherethe volatiles are rapidly removed from the particle, i.e.high heating rate, high temperature and small particles.The second part of this thesis deals with slow pyrolysis inpresence of steam for preparation of active carbon. Theinfluence of the type of biomass, the type of reactor and thetreatment conditions, mainly temperature and activation time,on the properties and the yield of active carbons are studied.The precursors used in the experiments are birch (wood) anddifferent types of agricultural residues such as sugarcanebagasse, olive waste, miscanthus pellets and straw in untreatedand pelletized form.The results from the pyrolysis of biomass in presence ofsteam are compared with those obtained in inert atmosphere ofnitrogen. The steam contributes to the formation of solidresidues with high surface area and good adsorption capacity.The yield of liquid products increases significantly at theexpense of the gaseous and solid products. Large amount ofsteam result in liquid products consisting predominantly ofwater-soluble polar compounds.In comparison to the stationary fixed bed reactor, therotary reactor increases the production of energy-rich gases atthe expense of liquid products.The raw materials have strong effect on the yields and theproperties of the pyrolysis products. At equal time oftreatment an increase of the temperature results in a decreaseof the yield of solid residue and improvement of the adsorptioncapacity until the highest surface area is reached. Furtherincrease of the temperature decreases the yield of solidproduct without any improvement in the adsorption capacity. Therate of steam flow influences the product distribution. Theyield of liquid products increases while the gas yielddecreases when the steam flow is increased.Keywords: rapid pyrolysis, pyrolysis, wood, agriculturalresidues,biomass, char, tar, gas, char reactivity,gasification, steam, active carbon
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| 26. |
- Zanzi, Rolando, et al.
(författare)
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Rapid pyrolysis of agricultural residues at high temperature
- 2002
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 23:5, s. 357-366
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with rapid pyrolysis of agricultural residues such as olive waste and straw at high temperature (800 -1000degreesC) in a free-fall reactor at pilot scale. The conditions are of interest for gasification in fluidized beds where rapid pyrolysis plays an important role as first stage. The objective of the work is to study the effect of the process conditions such as heating rate, temperature and particle size on the product distribution, gas composition and char reactivity. A higher temperature and smaller particles increase the heating rate resulting in a decreased char yield. The cracking of the hydrocarbons with an increase in the hydrogen content is favoured by a higher temperature and by using smaller particles. Wood gives more volatiles and less char than straw and olive waste. The higher ash content in agricultural residues favours the charring reactions. The higher lignin content in olive waste results in a higher char yield in comparison with straw. Chars from olive waste and straw are more reactive in gasification than chars from birch because of the higher ash content.
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| 29. |
- Zanzi Vigouroux, Rolando, 1954-, et al.
(författare)
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BIOMASS TORREFACTION
- 2004
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Ingår i: 2nd World Conf. on Biomass for Energy, Industry and Climate Protection. ; , s. 859-862
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Konferensbidrag (refereegranskat)abstract
- This paper presents a work on biomass torrefaction performed in a laboratory unit with a reactor tube of a length of 0.5 m and an inner diameter of 0.04 m. The experiments are conducted with miscanthus, birch, salix as well as with wood and straw pellets. The reactor was heated to the selected temperature (230°C, 250°C or 280°C) and kept at the final temperature for a period of 1, 2 or 3 hours. The effect of the raw material, temperature, and residence time on the properties of the torrefied products is studied. The torrefied biomass products are characterized with elemental composition, energy content, moisture content, ash content and volatile fraction. The gaseous products are also analysed. The type of biomass influenced the product distribution. During torrefaction biomass undergoes changes in physical and chemical properties. The fixed carbon content and energy density increase with both time and temperature of torrefaction, while the yield on a weight basis decreases. The torrefied biomass has hydrophobic properties and a higher calorific value than the raw material.
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| 31. |
- Zanzi Vigouroux, Rolando, 1954-, et al.
(författare)
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FIXED BED UPDRAFT GASIFICATION OF BIOMASS
- 2005
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Ingår i: 14th European Biomass Conference and Exhibition. - : ETA-Florence, Italy and WIP-Munich, Germany. - 8889407077
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Konferensbidrag (refereegranskat)abstract
- The paper presents the initial work performed in a newly built updraft gasifier. Densified woody biomass, birch, in form of pellets with a diameter of 8 mm and a length between 5 and 15 mm has been used as a raw material for batch autothermal gasification using air as an oxidation agent. The main objectives were to study the effect of the treatment conditions on the distribution of the products and the composition of product gas to establish the suitability of the gasifier to produce combustible gas with sufficiently high calorific value.The amount of the biomass used in the experiments was varied between 1 and 4 kg and the flow rate of the oxidation agent, air, was varied from 1,1 to 2,6 m3/h. Increased airflow rates favored higher temperatures, however, excessively high airflow rates resulted in fast consumption of the biomass and it also favored combustion over gasification and thus formation of lower amounts of combustible products. High airflow rates caused also higher yields of liquid products, due to the shorter residence time of the tar-rich gas in the gasifier and thus unfavorable conditions for tar cracking.
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| 32. |
- Zanzi Vigouroux, Rolando, 1954-, et al.
(författare)
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Fixed (slow-moving) bed updraft gasification of agricultural residues
- 2006
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Konferensbidrag (refereegranskat)abstract
- A laboratory-scale countercurrent fixed-bed gasifier has been designed and constructed to produce datafor process modelling and to compare the gasification characteristics of several biomasses. Densified woodybiomass, birch, in form of pellets with a diameter of 8 mm and a length between 5 and 15 mm has been used as a rawmaterial for batch autothermal gasification using air as an oxidation agent. The main objectives were to study theeffect of the treatment conditions on the distribution of the products and the composition of product gas to establishthe suitability of the gasifier to produce combustible gas with sufficiently high calorific value. The influence of theair flow rates on the composition of the producer gas has been studied. The amount of the biomass used in theexperiments was varied between 1 and 4 kg and the flow rate of the oxidation agent, air, was varied from 1,1 to 2,6m3/h.
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| 33. |
- Zanzi Vigouroux, Rolando, 1954-, et al.
(författare)
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Gasificación de pellets de madera en un reactor en flujo ascendente
- 2006
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Ingår i: Revista Ciencias Exatas. - : Universidade de Taubaté. - 1516-2893. ; 12:1, s. 63-69
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Tidskriftsartikel (refereegranskat)abstract
- El trabajo presenta los resultados de la gasificación de madera pelletizada de abedul en un reactor discontinuo de lecho ascendente. En los experimentos realizados se cargo el gasificador y se realizo el ensayo sin volver a alimentar el gasificador. Es decir se gasificó solo una carga. Se varió la carga utilizada (3 y 4 kg de madera pelletizada) y el flujo de aire (entre 1.1 m3/h y 2.6 m3/h). El gas producido por la gasificación esta compuesto de CO2, CO, H2, CH4 y hidrocarburos livianos. Las mayores concentraciones de los gases producidos por la gasificación y ricos en energía son 19% de CO, 7% de H2, 4 % de C4, y 1% de hidrocarburos livianos [C2 (etano, eteno y acetileno)]. El efecto predominante del aumento del flujo de aire es una mayor temperatura en el gasificador. El proceso de gasificación mejora debido a una mayor temperatura y a un aumento de la cantidad de dióxido de carbono producida por una mayor combustión. A mayor velocidad de gasificación aumenta la producción de monóxido de carbono y el contenido calorífico del gas producido es mayor. La cantidad de líquidos aumenta con el flujo de aire.
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| 35. |
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| 36. |
- Zanzi Vigouroux, Rolando, 1954-, et al.
(författare)
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Preparation of Activated Carbon : Forest residues activated with Phosphoric Acid and ZincSulfate
- 2011
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Ingår i: VII EDICIÓN DE LA CONFERENCIA CIENTÍFICA INTERNACIONAL MEDIOAMBIENTE SIGLO XXI, MAS XXI 2011.
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Konferensbidrag (refereegranskat)abstract
- This paper describes the preparation of activated carbon by chemical activation. The selected biomass used as precursor is sawdust from both Cuban and Swedish Pine tree. Phosphoric acid and Zinc Sulphate are the chemical reagents. The objective is to study the influence of acid concentration, impregnation ratio and activation temperature on adsorption performance of the obtained activated carbon. The experiments with phosphoric acid activation show that treatment with 40% acid concentration at 400 °C produce an activated carbon with good properties for ammonia adsorption and good iodine number. If a 30% phosphoric acid is used for activation, an activation temperature of 500 °C is recommended. With an impregnation ratio of 1, good adsorption was obtained in the activated carbon produced from Swedish pine while using Cuban pine a higher adsorption was obtained with an impregnation ratio of 2. The experiments with Zinc Sulphate activation show that activation conditions of 20% zinc sulphate concentration, 400 °C and impregnation ratio: 1 are enough to produce an activated carbon with good properties for ammonia adsorption. The adsorption of carbon tetrachloride was lower. Activated carbons produced with 10 % zinc sulphate concentration, 0.5 impregnation ratio and 400 °C activation temperature (the mildest studied conditions) show already good iodine number and BET surface area.
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