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Henrik Thunman - One of the best experts on this subject based on the ideXlab platform.
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Effect of ash circulation on the performance of a dual Fluidized Bed Gasification system
Biomass & Bioenergy, 2018Co-Authors: Sébastien Pissot, Teresa Berdugo Vilches, Henrik Thunman, Martin SeemannAbstract:Abstract During Gasification of biomass, ash forming elements are released from the fuel and some of these elements can have a positive impact on the quality of the gas produced. In a dual Fluidized Bed (DFB) gasifier, a significant amount of these components are found in the fly ash from the Gasification and combustion reactors. In order to increase carbon conversion and Bed material recovery, these streams are generally circulated back to the combustor for the raw gas fly ash and in some cases to the gasifier for the flue gas fly ash. The impact on the Gasification performance has, however, not been investigated. Circulation of flue gas coarse ash was carried out in the Chalmers gasifier, with the aim of assessing the impact on gas quality, in particular in term of tar yields, and how it relates to the flow and properties of ash streams. The coarse ash was first enhanced by an injection of untreated olivine in a fine particle size and was then recirculated, yielding a direct decrease in tar concentration. This effect persisted after the recirculation and the Bed activity was seen to increase with time, at a higher rate than a reference aging experiment. Both the internal Bed material cycle and the external fly ash loop were found to get enriched in ash components, which was linked to the activity gains observed. These results show the potential of continuous fly ash recirculation as an activity enhancer in industrial dual Fluidized Bed Gasification systems.
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Upscaling Effects on Char Conversion in Dual Fluidized Bed Gasification
Energy & Fuels, 2018Co-Authors: Louise Lundberg, David Pallarès, Henrik ThunmanAbstract:Dual Fluidized Bed Gasification (DFBG) is an emerging technology that can be employed as a first step in the transformation of lignocellulosic materials into transportation fuels such as substitute natural gas, dimethyl ether, methanol, and Fischer–Tropsch diesel. The present work aims at (i) identifying challenges that arise in the upscaling of DFBG plants, (ii) determining whether the increased fuel residence time that results from the upscaling is sufficient for process optimization, and (iii) evaluating the impact of measures to mechanically control the fuel residence time. The investigations use a semiempirical 1-dimensional model, which is validated with industrial-scale measurements. The scope includes both DFBG units delivering gas as the main product and those in which the product gas is a byproduct in a heat and power plant. Moreover, both new designs and retrofit cases of existing CFB combustion plants (i.e., adding a gasifier to the return leg) are considered. Modeling results show that althou...
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Zero‐dimensional modeling of indirect Fluidized Bed Gasification
2017Co-Authors: Anton Larsson, Martin Seemann, David Pallarès, Daniel Santos Felix Neves, Henrik ThunmanAbstract:Zero-dimensional models has been developed to investigate mass balance and fuel (biomass) conversion in Chalmers 2-4 MWfuel indirect Fluidized Bed gasifier. The input to the model is measured concentrations and flows. The model shows that the conversion factor of the water gas shift reaction is around 40 %.
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Production of Activated Carbon within the Dual Fluidized Bed Gasification Process
Industrial & Engineering Chemistry Research, 2015Co-Authors: Placid A. Tchoffor, Kent Davidsson, Henrik ThunmanAbstract:A key step in the production of clean energy from biomass Gasification is the cleaning of the product gas to remove impurities, such as tars, H2S, HCl, particulates, and alkali compounds. Some gas cleaning systems employ activated carbon (AC), with Brunauer-Ernmett-Teller (BET) surface areas in the range of 800-1300 m(2)/g. Because the operational conditions for the production of AC are similar to those applied in the Gasification chamber of a dual Fluidized Bed gasifier, the possibility to produce AC within the dual Fluidized Bed Gasification (DFBG) process was investigated in the present work. Wood pellets were gasified with steam in a Fluidized Bed reactor at 800 and 840 degrees C. Part of the unconverted char from this process was further activated with steam in a fixed Bed reactor at 850 degrees C. The results obtained indicate that if >= 44% of the char that results from the devolatilization of the wood pellets is gasified (the extent of char conversion), the unconverted char acquires a BET surface area >900 m(2)/g, which makes it suitable for use in gas cleaning processes. Achieving this extent of char conversion in the Gasification chamber of industrial dual Fluidized Gasification plants would remove the need and cost for a second reactor for further activation of the unconverted char. The cost of the produced activated carbon (AC) has been estimated as being 15-fold lower than that of commercially available AC. This suggests that the production of AC as part of the dual Fluidized Bed Gasification process would be cost-effective.
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Using Ilmenite To Reduce the Tar Yield in a Dual Fluidized Bed Gasification System
Energy & Fuels, 2014Co-Authors: Anton Larsson, Mikael Israelsson, Fredrik Lind, Martin Seemann, Henrik ThunmanAbstract:Biomass Gasification plays an important role in the emerging production of second-generation biofuels. One of the major challenges facing biomass Gasification is to find simple and efficient ways to reform tar components. While the tar causes operational problems, it can be reformed to increase the chemical efficiency of the Gasification process. With respect to tar reforming, catalytic materials are of special interest. Many of the materials that have been proposed as promising catalysts are metal oxide-based materials. However, metal oxides also have the ability to transport oxygen when subjected to alternating oxidizing and reducing atmospheres, similar to that which occurs in a dual Fluidized Bed Gasification system. In this work, ilmenite was used as the catalytic material in the Chalmers 2–4 MWth dual Fluidized Bed gasifier to decrease the yield of tar. The ilmenite was mixed with the silica sand, which was used as the Bed material, to investigate how the level of ilmenite affected chemical efficien...
Viboon Sricharoenchaikul - One of the best experts on this subject based on the ideXlab platform.
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Mitigating Bed agglomeration in a Fluidized Bed gasifier operating on rice straw
Energy Reports, 2020Co-Authors: Jurarat Nisamaneenate, Anun Seemen, Duangduen Atong, Viboon SricharoenchaikulAbstract:Abstract Fluidized Bed gasifier is a promising technology with respect to converting biomass to useful energy. Bed agglomeration is an operational challenge that arises during Fluidized Bed Gasification with rice straw as raw materials. Rice straw contains high amounts of potassium and other components that may lower the melting point of ash, causing Bed agglomeration. Using alternative Bed materials such as alumina, in the place of silica, can mitigate this problem. In Thailand, rice straw is an agricultural by-product of the rice milling processes, produced in large quantities every year. Usually, rice straw management comprises open field burning, which releases greenhouse gases, particulate matter, and other pollutants. In this paper, the behaviors of Bed agglomeration and defluidization were investigated during the Fluidized Bed Gasification of rice straw, using silica and alumina as Bed materials. The effect of the percentage ratio of silica and alumina (0:100; 25:75; 50:50; 75:25; 100:0) was examined. The operating parameters were as follows: rice straw particle size of 425– 850 μ m , reaction temperature of 700–900 °C, and equivalence ratios (ER) of 0.2 and 0.4. The results showed that the percentage ratio of silica and alumina, 0:100 at 700 °C, had extended the defluidization time of 60 min. The effect of equivalence ratio on Bed agglomeration was found to be apparently heightened at a high temperature. The result of SEM/EDX analysis showed that the major elements at the linkage point of the agglomerated particle were Si, K, and Ca, with regard to any proportion of the alumina Bed and temperature. In conclusion, low temperature agglomerate formation can be explained by a K 2 O-CaO-Si2O phase diagram. The results from this investigation can be applied to biomass-Fluidized Bed Gasification, where Bed agglomeration entails a plant shutdown and is expensive in terms of maintenance.
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Effect of Silica and Alumina Ratio on Bed Agglomeration During Fluidized Bed Gasification of Rice Straw
2018 2nd International Conference on Green Energy and Applications (ICGEA), 2018Co-Authors: Anun Seemen, Duangduen Atong, Viboon SricharoenchaikulAbstract:Bed agglomeration is one operational challenge during Fluidized Bed Gasification when rice straw is used as raw materials. Rice straw contains high potassium and other components which may lower ash melting point causing Bed agglomeration. This study focused on the effect of alumina and silica ratio of Bed materials in Fluidized Bed gasifier. The ratio of alumina Bed was 0, 0.25, 0.50, 0.75 and 1.0. The experiments were performed at 700, 800 and 900°C with equivalence ratio (ER) of 0.2. Rice straw size 425–850 μm was used as raw materials. The result showed that the high ratio of alumina deceased Bed agglomeration at 700°C. However, similar alumina ratio increased Bed agglomeration at 800 and 900°C. In addition, the effect of temperature on defluidization time was significant. As the operating temperature increased, the defluidization time decreased. Although the ratio of the Bed material was different but the result of defluidization time show a similar trend. As a result, high operating temperature may not suitable for Fluidized Bed Gasification with this particular biomass. The SEM/EDS analyzed showed that potassium, calcium and silicate are major element in a linkage between Bed particles. As a result, 75% of alumina Bed ratio at 700°C was sufficient to avoid Bed agglomeration during Fluidized Bed Gasification of rice straw. In conclusion, specific ratio of alumina and silica can prevent agglomeration in Fluidized Bed Gasification of rice straw when operating temperature lower than apparent eutectic melting point of involved alkalis from rice straw. The result from this investigation may lead to options on mitigating the problem of Bed agglomeration in Fluidized Bed gasifier of rice straw.
Umberto Arena - One of the best experts on this subject based on the ideXlab platform.
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Energy recovery from plastic and biomass waste by means of Fluidized Bed Gasification: A life cycle inventory model
Energy, 2018Co-Authors: Filomena Ardolino, Concetta Lodato, Thomas Fruergaard Astrup, Umberto ArenaAbstract:Abstract The study provides for the first time a life cycle inventory model for the Fluidized Bed Gasification of wastes, based on a large amount of high-quality data. All of them have been obtained from a pilot scale Fluidized Bed gasifier, fed with ten types of waste and biomass, under a wide range of operating conditions. The model refers to commercial scale gasifiers having a “thermal configuration”, where the generated syngas is immediately burned downstream of the reactor. Key relationships between process- and waste-specific parameters have been defined. The model quantifies the main inputs and outputs of the Gasification process (emissions, energy recovery, ash disposal, resource consumptions), providing high-quality data that could contribute to improve life cycle assessment modelling of waste Gasification. Finally, some case studies have been implemented in the EASETECH software to illustrate the model applicability, evaluate the role of main parameters, and compare the environmental performances of Gasification power units with that of the European electricity mix. The performances appear highly affected by metal contents in the waste-derived fuels, while the model results to a limited extent are sensitive to the equivalence ratio and the net electrical efficiency of the energy conversion.
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Fluidized Bed Gasification of industrial solid recovered fuels.
Waste Management, 2016Co-Authors: Umberto Arena, Fabrizio Di GregorioAbstract:The study evaluates the technical feasibility of the Fluidized Bed Gasification of three solid recovered fuels (SRFs), obtained as co-products of a recycling process. The SRFs were pelletized and fed to a pilot scale bubbling Fluidized Bed reactor, operated in Gasification and co-Gasification mode. The tests were carried out under conditions of thermal and chemical steady state, with a Bed of olivine particles and at different values of equivalence ratio. The results provide a complete syngas characterization, in terms of its heating value and composition (including tars, particulates, and acid/basic pollutants) and of the chemical and physical characterization of Bed material and entrained fines collected at the cyclone outlet. The feasibility of the Fluidized Bed Gasification process of the different SRFs was evaluated with the support of a material and substance flow analysis, and a feedstock energy analysis. The results confirm the flexibility of Fluidized Bed reactor, which makes it one of the preferable technologies for the Gasification of different kind of wastes, even in co-Gasification mode. The Fluidized Bed Gasification process of the tested SRFs appears technically feasible, yielding a syngas of valuable quality for energy applications in an appropriate plant configuration.
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Fluidized Bed Gasification
Fluidized Bed Technologies for Near-Zero Emission Combustion and Gasification, 2013Co-Authors: Umberto ArenaAbstract:Abstract: The chapter describes the state-of-the-art of Fluidized Bed Gasification of solid fuels, starting from the key role played by hydrodynamics, and its strong correlation with physical and chemical phenomena of the process and operating performance parameters of the reactor. The possible configurations of Fluidized Bed Gasification plants are also assessed, and an analysis of the main methods for syngas cleaning is reported. Finally, the chapter describes some of the most interesting commercial experiences. The analysis indicates that the Gasification of biomass and also of municipal and industrial solid wastes appear to be the most interesting sectors for the industrial development and utilization of Fluidized Bed gasifiers.
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Fluidized Bed Gasification of biomass: a substance flow analysis
2011Co-Authors: Umberto Arena, Fabrizio Di Gregorio Lucio Zaccariello, Maria Laura MastelloneAbstract:A natural biomass was fed in a pilot scale bubbling Fluidized Bed gasifier, having a maximum feeding capacity of 100kg/h. Measurements included the syngas composition, the mass flow rate and composition of entrained fines collected at the cyclone and purge material from the wet scrubber, and the Bed material characterization. The performance of the whole Gasification plant and of its specific components as well as the validity of some design solutions and operating criteria have been quantitatively assessed by means of a substance flow analysis.
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Fluidized Bed Gasification of waste derived fuels
Waste Management, 2010Co-Authors: Umberto Arena, Lucio Zaccariello, Maria Laura MastelloneAbstract:Five alternative waste-derived fuels obtained from municipal solid waste and different post-consumer packaging were fed in a pilot-scale bubbling Fluidized Bed gasifier, having a maximum feeding capacity of 100 kg/h. The experimental runs utilized Beds of natural olivine, quartz sand or dolomite, Fluidized by air, and were carried out under various values of equivalence ratio. The process resulted technically feasible with all the materials tested. The olivine, a neo-silicate of Fe and Mg with an olive-green colour, has proven to be a good candidate to act as a Bed catalyst for tar removal during Gasification of polyolefin plastic wastes. Thanks to its catalytic activity it is possible to obtain very high fractions of hydrogen in the syngas (between 20% and 30%), even using air as the gasifying agent, i.e. in the most favourable economical conditions and with the simplest plant and reactor configuration. The catalytic activity of olivine was instead reduced or completely inhibited when waste-derived fuels from municipal solid wastes and aggregates of different post-consumer plastic packagings were fed. Anyhow, these materials have given acceptable performance, yielding a syngas of sufficient quality for energy applications after an adequate downstream cleaning.
Maria Laura Mastellone - One of the best experts on this subject based on the ideXlab platform.
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Fluidized Bed Gasification of biomass: a substance flow analysis
2011Co-Authors: Umberto Arena, Fabrizio Di Gregorio Lucio Zaccariello, Maria Laura MastelloneAbstract:A natural biomass was fed in a pilot scale bubbling Fluidized Bed gasifier, having a maximum feeding capacity of 100kg/h. Measurements included the syngas composition, the mass flow rate and composition of entrained fines collected at the cyclone and purge material from the wet scrubber, and the Bed material characterization. The performance of the whole Gasification plant and of its specific components as well as the validity of some design solutions and operating criteria have been quantitatively assessed by means of a substance flow analysis.
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Fluidized Bed Gasification of waste derived fuels
Waste Management, 2010Co-Authors: Umberto Arena, Lucio Zaccariello, Maria Laura MastelloneAbstract:Five alternative waste-derived fuels obtained from municipal solid waste and different post-consumer packaging were fed in a pilot-scale bubbling Fluidized Bed gasifier, having a maximum feeding capacity of 100 kg/h. The experimental runs utilized Beds of natural olivine, quartz sand or dolomite, Fluidized by air, and were carried out under various values of equivalence ratio. The process resulted technically feasible with all the materials tested. The olivine, a neo-silicate of Fe and Mg with an olive-green colour, has proven to be a good candidate to act as a Bed catalyst for tar removal during Gasification of polyolefin plastic wastes. Thanks to its catalytic activity it is possible to obtain very high fractions of hydrogen in the syngas (between 20% and 30%), even using air as the gasifying agent, i.e. in the most favourable economical conditions and with the simplest plant and reactor configuration. The catalytic activity of olivine was instead reduced or completely inhibited when waste-derived fuels from municipal solid wastes and aggregates of different post-consumer plastic packagings were fed. Anyhow, these materials have given acceptable performance, yielding a syngas of sufficient quality for energy applications after an adequate downstream cleaning.
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tar removal during the Fluidized Bed Gasification of plastic waste
Waste Management, 2009Co-Authors: Umberto Arena, Lucio Zaccariello, Maria Laura MastelloneAbstract:Abstract A recycled polyethylene was fed in a pilot plant bubbling Fluidized Bed gasifier, having an internal diameter of 0.381 m and a maximum feeding capacity of 90 kg/h. The experimental runs were carried out under various operating conditions: the Bed temperature was kept at about 850 °C, the equivalence ratio varied between 0.2 and 0.35, the amount of Bed material was between 131 and 215 kg, the fluidizing velocity was between 0.5 and 0.7 m/s, quartz sand and olivine were used as Bed material, and air and steam were used as fluidizing reactants. The results confirm that the tar removal treatments applied inside the gasifier (primary methods) can eliminate or strongly reduce the need for a further downstream cleanup of the syngas. In particular, the utilization of a natural olivine as an in situ tar reduction agent remarkably improves the quality of the product gas, in terms of both high hydrogen volumetric fraction and larger syngas yield.
Jia-chi Hung - One of the best experts on this subject based on the ideXlab platform.
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Influence of different fluidization and Gasification parameters on syngas composition and heavy metal retention in a two-stage Fluidized Bed Gasification process
Environmental Science and Pollution Research, 2021Co-Authors: Jia-hong Kuo, Chiou-liang Lin, Jia-chi HungAbstract:Herein, we investigated the influence of Gasification and fluidization parameters on the H_2 content of syngas and the retention of heavy metals (Cu and Pb) in a Bed material during a two-stage Fluidized Bed Gasification process. The results indicated that a temperature of 900 °C in both stages resulted in the highest H_2 content (32.4 mol%) in syngas. When different equivalence ratios (ERs) were investigated, it was found that the highest H_2 content in syngas (25.4 mol%) was achieved at an ER of 0.3. A particle size of 0.46 mm in the Fluidized Bed led to an increase in the H_2 content of syngas. Moreover, increasing the operating gas velocity led to an increase in the H_2 content of syngas. The heavy metal concentration in the Bed material was the highest at 500 °C. When the influences of different particle sizes and operating gas velocities were compared, it was observed that a particle size of 0.46 mm and gas velocity of 1.5 U/U_mf resulted in increased heavy metal concentrations in the Bed material, which indicates that the reduction in the particle size and the increase in the operating gas velocity enhanced Gasification and improved the retention of heavy metals.