1,720,978 research outputs found
Hydrogen production from biomass via gasification process: The results of the eu UnifHY project
No full textThis paper quotes an overview of the UNIfHY project results regarding pure hydrogen production from biomass gasification. Tests with different gasification agents (steam/air/oxygen) and at different temperatures showed syngas yield from 1.1 to 1.7 Nm3 dry/kg of dry biomass, hydrogen content from 20 to 40%-v dry, tars, particulate in the range of 10-20 g/Nm3 dry, sulphur and chlorine compounds in the range of 50-90 ppmv, ammonia up to 1600 ppmv. Candle filters showed particulate removal efficiency higher than 99%-wt. A portable purification system (PPS) consisting in a ZnO guard bed reactor, a water gas shift reactor (WGS), compressor and gas upgrading unit (PSA) was designed and realized. The system was proven to be operable stably and continuously in experimental runs lasting more than 12 h. Hydrogen production at concentration of 99.99%-v was achieved with an H2 yield from PSA of 66.4%. Based on the data collected, UNIfHY can reach an economic production cost of 3-10 €/kg H2 (in the range 4.00-0.04 t H2/day, respectively) with low environmental impact (0.5-2.4 kg CO2/kg H2) but targets have to be different for decentralised (40% efficiency, 10 years lifetime, <10 €/kg cost, production of electricity and heat) and centralised (70%, 20 years, <5 €/kg no electricity neither heat) production and higher performance and reliability can be achieved by means of the implementation of better configurations. © 2017, ETA-Florence Renewable Energies. All right reserved
CO2 sorption-enhanced processes by hydrotalcite-like compounds at different temperature levels
No full textThe aim of this work is to identify solid sorbents for CO2 capture for coal and biomass syngas conditioning and cleaning by means of a sorption-enhanced reaction process. Hydrotalcite-like compounds (HTlcs) were synthesized with and without K2CO3 impregnation. Samples were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) porosimetry after synthesis and after capture tests, respectively. Sorption and desorption tests were performed in a fluidized bed reactor, under cyclic conditions, at two different temperature levels: 350/450°C and 600/700°C. At low temperature only the Mg-Al HTlcs K promoted samples showed stability and sorption capacity comparable with literature values. On the other hand, results at high temperature indicate that the mixed Mg-Ca-Al HTlcs samples exhibit the best behavior with the highest sorption capacity (1.7 mmol CO2 /g) almost stable over 5 sorption/regeneration cycles; furthermore, addition of steam allowed increasing their reactivity by 70% compared to the dry value. This type of sorbent could be a promising candidate to prepare a bifunctional sorbent-catalyst for sorption-enhanced processes, taking place directly in the fluidized bed gasifier, or downstream the reactor for adjustment of gas composition before further conversion in gaseous energy carriers. © 2015 by De Gruyter
Performance tests with a SOFC unitfuelled with syngas produced from biomass gasification ractors, properly conditioned and cleaned
No full textBiomass gasification and BioSNG production: Use of sorbents for simultaneous H2 enrichment and CO2 removal for the conditioning of gas composition
No full textUse of sorbents for sorption enhanced water gas shift (SEWGS) were considered to adjust the composition of the product gas obtained from a process of biomass gasification and convert it in BioSNG. To this purpose four sorbents were prepared and tested in experiments of SEWGS with a real gas obtained at a 1000 kWth pilot plant based on the process of steam/oxygen biomass gasification. The selected sorbents were two K-enriched hydrotalcites Mg/Al (HT1K and PMG70/K), a hydrocalumite Ca/Al (HT2) and a mixed hydrotalcite Mg/Ca/Al (HT3). The two Mg/Al materials were selected for cyclic tests of SEWGS at 400 °C (low temperature), the other two for evaluations at 600 °C (high temperature). Based on the experimental results, average and rather stable, CO2- uptake capacities of about 0.9 and 0.7 mmolCO2/gsorbent were respectively evaluated for HT1K and PMG70/K; for HT2 and HT3 the average uptake capacities were correspondingly found to be 2.6 and 3.1 mmolCO2/gsorbent. By comparing the structural properties of the materials before and after tests, no relevant modifications were observed based on results from SEM-EDX and XRD, as well as no presence of residual contaminants from tars were detected based on the FTIR spectrum. Preliminary data from modelling for the processes carried out at 400 °C and 600 °C, indicated a conversion efficiency from biomass to BioSNG up to 56 % and 45 %, respectively. © 2017, ETA-Florence Renewable Energies. All rights reserved
Bioremediation of wastewater stream from syngas cleaning via wet scrubbing
No full textBiomass gasification is a process known for its high potential in enabling the exploitation of residual biomass in the production of renewable electricity. At present one of the most favorable patterns from both an environmental and a sustainability point of view is air gasification coupled with an Internal Combustion Engine (ICE) for decentralized production. In order to have the best performances of the ICE to be run with the produced gas, the required technical specifications on gas purity can be achieved at an appropriate level by means of wet scrubbing. In wet gas cleaning approach, stages based on organic liquids (e.g. biodiesel) and water can be jointly adopted for the removal of contaminants. In the present work preliminary results for the regeneration of the wastewater stream produced at a gasification plant whose gas cleaning is carried out with a purification train based on biodiesel and water scrubbing are presented. To this aim three different fungal strains were selected and tested for their bioremediation potential, i.e. Bjerkandera adusta, Arthrinium sp, and Pleurotus ostreatus. Laboratory tests gave an overall positive response on the effectiveness of wastewater treatment by Bjerkandera adusta and Arthrinium sp. thus demonstrating that these microorganisms are able to metabolize, and therefore remove, both aromatic molecules typical of tar produced in gasification processes, and esters of fatty acids constituting the biodiesel used for gas washing in the first stage
Use of experimental catalysts for production of bio-methane from biomass: Tests of methanation with real syngas and performance evaluations
No full textThe methanation of a real gas produced from almond shells via steam/oxygen gasification is investigated. The performance of an experimental Ni-containing catalysts (Ni23.7Mg56.3Al20) was evaluated by using the material prepared in grains of 1-2 mm. The real gas was enriched with hydrogen at two different H2/COx mole ratios. All tests were carried out at operating conditions of 400 ÷ 450 °C and 25 bara. Checks with a defined reactive gas mixture provided indication about the activity state of the catalysts before and after the methanation. During all the stages of the tests the outlet gas composition was monitored and after each complete run the catalyst analyzed. Under the operating conditions adopted, the experimental catalyst showed a higher methane yield (+10% and +44%) at both H2 enrichment levels and no carbon deposition was observed, as demonstrated by after-test catalyst samples evaluated via Raman spectroscopy coupled with optical microscopy and SEM-EDAX analysis. © 2017, ETA-Florence Renewable Energies. All rights reserved
Performance tests with a SOFC unit fuelled with syngas produced from biomass gasification reactors, properly conditioned and cleaned
No full textPerformance tests were completed with a SOFC unit fuelled with syngas produced from biomass gasification reactors, properly conditioned and cleaned. Three series of tests at bench and industrial scale were completed. The results of the tests indicate that cleaned syngas, from both steam blown gasifier and oxygen/steam blown gasifier reactor, is a feasible fuel for anode supported SOFC cell. Cell performance on cleaned syngas is comparable or better than SOFC cell performance fuelled with the reference, hydrogen/nitrogen gas mixture. Several potential issues for the integrated SOFC/gasifier operation were identified. Proper humidification of the gas stream, necessary to avoid carbon deposition, is critical for the long term cell performance. The presence of larger amounts of methane and higher hydrocarbons may lead to SOFC cell cracking due to large temperature gradients resulting from internal reforming process
Production of Gaseous Carriers Via Biomass Gasification for Energy Purposes
No full textAbstractIt is under development a biomass gasification plant based on a 1 MWth bubbling fluidized bed (BFB) reactor with internal recirculation. Compared to conventional BFB design, the mechanism of internal circulation of solids can give beneficial effect to the process in terms of biomass conversion efficiency into gaseous product and gas quality. A model describing the process of biomass gasification in the two reaction chambers was developed. Expected results were preliminarily validated by experimental results obtained at a bench scale facility working on the same gasification concept
CO2 sorption enhanced processes by hydrotalcite like compounds at different temperature levels.
No full textAir gasification of digestate and its co-gasification with residual biomass in a pilot scale rotary kiln
No full textIn this study energy recovery of digestate from a biogas plant was investigated via air gasification. Gasification tests were executed in a pilot scale rotary kiln plant having a nominal biomass feeding rate of about 20 kg/h. The equivalence ratio was varied from 0.22 to 0.39 with the goal to approach the autothermal condition. Tests were carried out for 5 h in steady state condition. Syngas composition, char and gas yields were measured. To improve the cold gas efficiency of the process, a mixture of digestate and almond shells (60:40 wt%) was gasified. Autothermal condition was reached with the mixture using equivalence ratio of 0.30 where the corresponding cold gas efficiency achieved the maximum value of 55%. The raw gas had a lower heating value of 4–5 MJ/Nm3. To evaluate possible improvements in the produced gas properties, in this work the effect of steam injection was also investigated
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