STUDY OF THE BEHAVIOUR OF A CATALYTIC CERAMIC CANDLE FILTER IN A LAB-SCALE UNIT AT HIGH TEMPERATURES

Solid particles and tars are among the non-desirable products of synthesis gas produced during biomass gasification. Removal of fly ashes is necessary in order to comply with emission limits as well as avoid their deposition in downstream units. Condensation of tars, on the other side, can cause clogging. A catalytic hot gas filter can remove both solids and tars, when operating at temperatures as high as 850oC. Catalytic hot gas filter elements are under development in order to solve this issue. A lab-scale filtration unit has been designed and constructed at Delft University of Technology. The unit contains one ceramic hot gas filter candle which is made of a SiC porous structure coated with a mullite membrane. The integration of a Nickel-based catalyst layer allows the dual function of particle filtration and tar cracking. The filter vessel is part of a set-up that is equipped with a tar evaporator and a pre-heater, both located upstream of the filter unit. This paper presents the results of the first set of experimental tests that have been performed with this unit. A dust-free model gas was used and consisted of a mixture of CO (14%), CO2 (14%), H2 (7%), CH4 (5%), and varying concentrations of N2 (30, 40, 50%) and H2O (30, 20, 10%). Naphthalene (2g/Nm3 and 5g/Nm3) was adopted as model compound in order to study the catalytic conversion of heavier hydrocarbon species to H2. A gas face velocity of 2.5cm/s was selected for tests performed at atmospheric conditions and at operating temperatures varying between 700oC and 850oC. The pressure drop through the filter candle was continuously monitored during the process. The gas composition was measured upstream and downstream of the filter unit by means of an on-line micro-GC, while naphthalene concentration was attained with the SPA method. The following findings were obtained: higher naphthalene conversion with increasing temperatures and better conversion at any temperature when 2g/Nm3 were used compared to 5g/Nm3. Tests at 850oC and 30 vol% H2O produced a conversion of 99.4% with 2g/Nm3 while 98.5% with 5g/Nm3. Experiments with higher steam content showed higher conversion values. Methane concentration was also affected thus indicating that reforming reactions took place as well. Pressure drop measurements showed that no carbon deposition occurred on the candle during the tests, even at lower temperatures. At this stage new experiments are being performed with different face velocities and tar compounds in order to provide enough data for future tests with real gasification gas

STUDY OF THE BEHAVIOUR OF A CATALYTIC CERAMIC CANDLE FILTER IN A LAB-SCALE UNIT AT HIGH TEMPERATURES

Solid particles and tars are among the non-desirable products of synthesis gas produced during biomass gasification. Removal of fly ashes is necessary in order to comply with emission limits as well as avoid their deposition in downstream units. Condensation of tars, on the other side, can cause clogging. A catalytic hot gas filter can remove both solids and tars, when operating at temperatures as high as 850oC. Catalytic hot gas filter elements are under development in order to solve this issue. A lab-scale filtration unit has been designed and constructed at Delft University of Technology. The unit contains one ceramic hot gas filter candle which is made of a SiC porous structure coated with a mullite membrane. The integration of a Nickel-based catalyst layer allows the dual function of particle filtration and tar cracking. The filter vessel is part of a set-up that is equipped with a tar evaporator and a pre-heater, both located upstream of the filter unit. This paper presents the results of the first set of experimental tests that have been performed with this unit. A dust-free model gas was used and consisted of a mixture of CO (14%), CO2 (14%), H2 (7%), CH4 (5%), and varying concentrations of N2 (30, 40, 50%) and H2O (30, 20, 10%). Naphthalene (2g/Nm3 and 5g/Nm3) was adopted as model compound in order to study the catalytic conversion of heavier hydrocarbon species to H2. A gas face velocity of 2.5cm/s was selected for tests performed at atmospheric conditions and at operating temperatures varying between 700oC and 850oC. The pressure drop through the filter candle was continuously monitored during the process. The gas composition was measured upstream and downstream of the filter unit by means of an on-line micro-GC, while naphthalene concentration was attained with the SPA method. The following findings were obtained: higher naphthalene conversion with increasing temperatures and better conversion at any temperature when 2g/Nm3 were used compared to 5g/Nm3. Tests at 850oC and 30 vol% H2O produced a conversion of 99.4% with 2g/Nm3 while 98.5% with 5g/Nm3. Experiments with higher steam content showed higher conversion values. Methane concentration was also affected thus indicating that reforming reactions took place as well. Pressure drop measurements showed that no carbon deposition occurred on the candle during the tests, even at lower temperatures. At this stage new experiments are being performed with different face velocities and tar compounds in order to provide enough data for future tests with real gasification gas

A modeling based study on the integration of 10 MWth indirect torrefied biomass gasification, methanol and power production

This work is focused on the process system modelling of an indirectly heated gasifier (10 MWth) using torrefied wood as feedstock and its integration with methanol and power production using Aspen Plus®. The modelling of the gasification process along with the obtained reaction kinetics were validated with experimental data found in literature. Different processing steps such as gasification, gas cleaning and upgrading, methanol synthesis and energy conversion, were modelled and their performance was optimized through a series of sensitivity studies. The results obtained were then used to investigate the effect of different technologies and the variation of operational parameters on the overall process performance. Three cases were examined: “syngas production” (case 1), “methanol production” (case 2), and “power production” (IGCC) (case 3). Case 1 and case 2 were simulated using sand and dolomite as bed materials respectively, in order to study the incorporation of Absorption Enhanced Reforming (AER) on the syngas and methanol production efficiency. For case 3 the simulation was performed for two different configurations: a conventional Integrated Gasification Combined Cycle (IGCC) and an innovative Inverted Brayton Cycle (IBC) turbine system. Dolomite was used as the bed material for both configurations. For case 1, an increase of 5% in hydrogen yield in the product gas when AER is applied was observed. For case 2, higer values of Cold Gas Efficiency and Net Efficiency (34% and 60% instead of 33% and 55%, respectively) and a slightly lower value of Carbon Conversion (96% instead of 100%) were obtained when AER was employed. Gasification temperature was lowered by 110 °C in this scenario. For case 3, a lower value of Net Efficiency was obtained when IBC was considered (43% instead of 47%), while a value of 60% was obtained for methanol production with AE. Moreover, the results of case 3, showed that the latent heat in the hot syngas is best utilised when IBC is considered. The developed model accurately predicted the composition of the produced gas and the operational conditions of all the identified blocks within the methanol synthesis and power production processes. This way the use of this model as a generic tool to compare the utilization of different technologies on the performance of the overall process was validated.Large Scale Energy StorageEnergy Technolog

Pilot scale steam-oxygen CFB gasification of commercial torrefied wood pellets. The effect of torrefaction on the gasification performance

Torrefaction is a promising biomass upgrading technology as it makes biomass more coal alike and offers benefits in logistics and handling operations. Gasification is an attractive thermochemical conversion technology due to its flexibility in the product gas end-uses. Therefore, it is valuable to investigate whether additional benefits are foreseen when torrefaction is coupled with gasification. Therefore, two commercial torrefied wood fuels and their parent materials are gasified at 800-850 degrees C under atmospheric steam-oxygen circulating fluidized bed gasification conditions and magnesite as bed material. The torrefied feedstocks consisted of wood residues torrefied by Topell at 250 degrees C (Topell black), and mixed wood and wood residues torrefied by Torrcoal at 300 degrees C (Torrcoal black). The gasification results show that torrefaction resulted in an increased gas quality, as it yielded higher H-2 and CO contents, a decrease of the CO2 content, increased gas yield and a significant decrease of the total tar content for both feedstocks. For the Torrcoal samples, torrefaction resulted in a decrease in the carbon conversion efficiency (CCE). In addition, the cold gas efficiency (CGE) remained approximately the same due to the increase in the H-2 and CO contents. The Topell samples showed an increase in the CCE and CGE upon torrefaction, but this could be attributed to a significant grinding in the screw feeder. It is generally concluded that both torrefied fuels may offer benefits as a feedstock for steam-oxygen blown circulating fluidized bed gasification, in particular in terms of gas quality and yield. (C) 2017 The Author(s). Published by Elsevier Ltd

Scientific Assessment in Support of the Materials Roadmap Enabling Low Carbon Energy Technologies: Bioenergy

This scientific assessment serves as the basis for a materials research roadmap for bioenergy technology, itself an integral element of an overall "Materials Roadmap Enabling Low Carbon Technologies", a Commission Staff Working Document published in December 2011. The Materials Roadmap aims at contributing to strategic decisions on materials research funding at European and Member State levels and is aligned with the priorities of the Strategic Energy Technology Plan (SET-Plan). It is intended to serve as a guide for developing specific research and development activities in the field of materials for energy applications over the next 10 years. This report provides an in-depth analysis of the state-of-the-art and future challenges for energy technology-related materials and the needs for research activities to support the development of bioenergy technology both for the 2020 and the 2050 market horizons. It has been produced by independent and renowned European materials scientists and energy technology experts, drawn from academia, research institutes and industry, under the coordination the SET-Plan Information System (SETIS), which is managed by the Joint Research Centre (JRC) of the European Commission. The contents were presented and discussed at a dedicated hearing in which a wide pool of stakeholders participated, including representatives of the relevant technology platforms, industry associations and the Joint Programmes of the European Energy Research Associations.JRC.F.2-Cleaner energ

Influence of nickel precursors on the properties and performance of Ni impregnated zeolite 5A and 13X catalysts in CO2 methanation

Zeolite 13X and 5A supported Ni catalysts were synthesized for CO2 methanation using the evaporation impregnation method. The influence of using different Ni precursors (nitrate, citrate, and acetate) as well as calcination temperatures on the catalyst properties and performance were investigated. XRD, SEM-EDX, TEM, STEM-EDX, N2 physisorption, H2-TPR, TPD-NH3 and TG/DTA were used for detailed characterization of the catalysts. The parent structure of the zeolites did not change during catalyst synthesis. Using nickel citrate and acetate resulted in smaller NiO particle size compared to nitrate. STEM-EDX results showed that all the Ni-precursor complexes entered more efficiently the 13X zeolite structure, which is mainly due to steric hindrance resulting from the smaller pore size of 5A. Methanation experiments revealed that the 13X catalysts synthesized using nickel citrate (5% Ni) displayed clearly higher activity, compared to the catalysts synthesized using nickel nitrate or nickel acetate. A 79% conversion at 320 °C was obtained with 100% selectivity towards CH4 and the catalyst showed excellent stability during 200 h testing. Overall, it can be concluded that the Ni precursor significantly influences the physico-chemical characteristics and catalytic properties of Ni 13X and Ni 5A zeolite catalysts in CO2 methanation: complex size and pore size matter.</p

Biomass pyrolysis TGA assessment with an international round robin

The large variations found in literature for the activation energy values of main biomass compounds (cellulose, hemicellulose and lignin) in pyrolysis TGA raise concerns regarding the reliability of both the experimental and the modelling side of the performed works. In this work, an international round robin has been conducted by 7 partners who performed TGA pyrolysis experiments of pure cellulose and beech wood at several heating rates. Deviations of around 20 – 30 kJ/mol were obtained in the activation energies of cellulose, hemicellulose and conversions up to 0.9 with beech wood when considering all experiments. The following method was employed to derive reliable kinetics: to first ensure that pure cellulose pyrolysis experiments from literature can be accurately reproduced, and then to conduct experiments at different heating rates and evaluate them with isoconversional methods to detect experiments that are outliers and to validate the reliability of the derived kinetics and employed reaction models with a fitting routine. The deviations in the activation energy values for the cases that followed this method, after disregarding other cases, were of 10 kJ/mol or lower, except for lignin and very high conversions. This method is therefore proposed in order to improve the consistency of data acquisition and kinetic analysis of TGA for biomass pyrolysis in literature, reducing the reported variability

Effectiveness of attentional bias modification training as add-on to regular treatment in alcohol and cannabis use disorder:A multicenter randomized control trial

BACKGROUND: Attentional bias for substance-relevant cues has been found to contribute to the persistence of addiction. Attentional bias modification (ABM) interventions might, therefore, increase positive treatment outcome and reduce relapse rates. The current study investigated the effectiveness of a newly developed home-delivered, multi-session, internet-based ABM intervention, the Bouncing Image Training Task (BITT), as an add-on to treatment as usual (TAU). METHODS: Participants (N = 169), diagnosed with alcohol or cannabis use disorder, were randomly assigned to one of two conditions: the experimental ABM group (50%; TAU+ABM); or the control group (50%; split in two subgroups the TAU+placebo group and TAU-only group, 25% each). Participants completed baseline, post-test, and 6 and 12 months follow-up measures of substance use and craving allowing to assess long-term treatment success and relapse rates. In addition, attentional bias (both engagement and disengagement), as well as secondary physical and psychological complaints (depression, anxiety, and stress) were assessed. RESULTS: No significant differences were found between conditions with regard to substance use, craving, relapse rates, attentional bias, or physical and psychological complaints. CONCLUSIONS: The findings may reflect unsuccessful modification of attentional bias, the BITT not targeting the relevant process (engagement vs. disengagement bias), or may relate to the diverse treatment goals of the current sample (i.e., moderation or abstinence). The current findings provide no support for the efficacy of this ABM approach as an add-on to TAU in alcohol or cannabis use disorder. Future studies need to delineate the role of engagement and disengagement bias in the persistence of addiction, and the role of treatment goal in the effectiveness of ABM interventions

Influence of Ni-Fe load in a bimetallic catalyst supported on Zeolite 13X for CO2 methanation in a fixed bed reactor

In this work three Ni-Fe catalysts supported on zeolite 13X were tested for CO2 methanation at different temperatures. The study shows the influence of the active species load on the synthesized catalysts. In addition, the effect of Ni-Fe ratio present on the catalysts was observed.&nbsp;En este trabajo se probaron tres catalizadores de Ni-Fe soportados en zeolita 13X para la metanación de CO2 a diferentes temperaturas. El estudio muestra la influencia de la carga de especies activas en los catalizadores sintetizados. Además, se observó el efecto de la ratio de Ni-Fe presente en los catalizadores