| 1. |
- Keller, Martin, 1985, et al.
(författare)
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Investigation of Natural and Synthetic Bed Materials for Their Utilization in Chemical Looping Reforming for Tar Elimination in Biomass-Derived Gasification Gas
- 2014
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 28:6, s. 3833-3840
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Tidskriftsartikel (refereegranskat)abstract
- The removal of condensable hydrocarbons or tars from raw gas derived from biomass gasification presents an obstacle in the widespread application of biomass gasification. Hot catalytic tar cleaning as a secondary tar removal strategy is discussed as a tar cleaning technology. This can be realized in a dual-fluidized-bed reactor system, in which a catalytically active bed material is continuously regenerated. Such a process is termed chemical looping reforming (CLR). In such a process, it has been suggested that oxygen carrier particles employed for chemical looping combustion may be used, with the oxygen transfer from the particles to the gas promoting tar decomposition. Experiments were conducted in a small-scale, batch-wise fluidized-bed reactor with the aim of investigating a variety of bed materials for this process. The purpose of the present work is thus to conduct a screening study of a variety of bed materials based on the transition metals Fe, Mn, Ni, and Cu. The experiments were conducted in a batch fluidized bed, where the particles are exposed to reformer and regenerator conditions alternatingly. The conversion of ethylene from a synthetic gasification gas mixture was used as an indicator for the suitability of the materials for tar conversion. It was found that the natural material bauxite and the synthetic bed materials NiO/alpha-Al2O3, CuO/MgAl2O4, and La0.8Sr0.2FeO3/gamma-Al2O3 exhibit high ethylene conversion rates and, thus, possess promising properties for their application in CLR
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| 2. |
- Alamia, Alberto, 1984, et al.
(författare)
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Design of an integrated dryer and conveyor belt for woody biofuels
- 2015
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 77, s. 92-109
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Tidskriftsartikel (refereegranskat)abstract
- Combustion or gasification of high-moisture content biomass is associated with a number of drawbacks, such as operational instabilities and lowered total efficiency. The present work proposes an integrated dryer and conveyor belt for woody biofuels with steam as the heat transfer medium. The use of low-temperature steam is favorable from a heat management point of view, but also helps to minimize the risk of fire, self-ignition and dust explosions. Furthermore, the presented dryer design represents an efficient combination of fuel transport, drying equipment and fuel feeding system.The proposed design is developed from a macroscopic energy and mass balance model that uses results from computational fluid dynamics (CFD) fuel bed modeling and experiments as its input. This CFD simulation setup can be further used to optimize the design with respect to bed height, steam injection temperatures and fuel type. The macroscopic model can be used to investigate the integration of the dryer within a larger biomass plant. Such a case study is also presented, where the dryer is tailored for integration within an indirect steam gasification system. It is found that the exergy efficiency of this dryer is 52.9%, which is considerably higher than those of other dryers using air or steam, making the proposed drying technology a very competitive choice for operation with indirect steam gasification units.
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| 3. |
- Bidgoli, Hosein, 1987, et al.
(författare)
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Terahertz Spectroscopy for Real-Time Monitoring of Water Vapor and CO Levels in the Producer Gas From an Industrial Biomass Gasifier
- 2014
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Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 4:6, s. 722-733
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a study of THz transmission spectroscopy as a novel tool for the monitoring of the steam and CO contents of the raw gas from industrial biomass gasifiers. A THz gas spectrometer with a frequency range of 300–500 GHz was designed and constructed. Proof-of-principle testing was performed at laboratory conditions using mixtures of different gases at high temperatures (600–700 K). The results demonstrate the feasibility of applying strong rotational water vapor lines at 448 and 383 GHz, so as to obtain reliable online measurements of water vapor with an absolute precision of about 0.2 vol.% for the current device. CO lines were identified at 461 and 346 GHz, facilitating measurement of this gas. The gas spectrometer was integrated into an industrial gasifier and boiler, and its performance was tested in terms of online measurements of steam and CO in the hot raw gas and flue gases under real-life conditions. Considering the error intervals, the results are in complete agreement with data acquired by solving loose mass balances around the system. The onsite experiments demonstrate that THz gas spectroscopy is a promising tool for fast, robust, and reliable monitoring in industrial applications.
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| 4. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
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Online Detection of H2O and CO in the Humid Raw Gas from the Gasifier Using Terahertz Spectroscopy
- 2013
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Ingår i: ICPS, 13 International Conference on Polygeneration Strategies, Sept.5-13, Vienna, Austria. - 9783950275483 ; , s. 51-58
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Konferensbidrag (refereegranskat)abstract
- The integration of a gasifier with a complex multistage synthesis process, such as SNG synthesis, demands a fast monitoring of the gasifier performance. However, despite the availability of standard analyzers for determination of dry gas composition, there are still many practical difficulties remaining in the online measurement of tar and steam in the raw gas. For the detection of steam concentration, electromagnetic waves at terahertz frequencies (102-104 GHz) are promising with regard to development of a robust online measurement device for industrial application. The main reason for the high potential is the low risk for interference with the wide range of other molecules and that the transmission of electromagnetic waves at THz frequencies is rather low sensitive to deposits and particulate matter in the course of the beam compared to the conventional and well established wavelengths like infrared. In the present work, a THz gas spectrometer was designed and constructed to check the feasibility of applying this measurement technique at industrial scale. For this purpose, continuous flows of raw gas with various water and CO contents from the Chalmers gasifier as well as a flue gas with known water content from the biomass combustor were introduced to the spectrometer set-up. H2O and CO compositions in each stream were determined in an online manner. The results confirmed the possibility of applying strong rotational water lines at 448 and 380 GHz to develop reliable devices for online measurement of water vapor with excellent error interval. However, some difficulties were encountered for simultaneous detection CO concentration with water within the frequency range studied in this work (300-500 GHz).
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| 5. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
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Terahertz Gas Spectrometer
- 2014
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Ingår i: Swedish Microwave Days March 11-12, 2014, Gothenburg, Sweden.
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Konferensbidrag (refereegranskat)abstract
- We present a 300-500GHz gas spectrometer built for and practically tested at the 2–4-MW indirect gasifier at the Chalmers Power Center. The primary goal is precise online measurements of H2O vapor and CO concentrations in the producer gas. Experimentally obtained H2O vapor concentration resolution was about 1% at the conditions of 50% VMR and 400 deg.C.
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| 6. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
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Terahertz Spectroscopy Instrumentation for Thermal Bio-Mass Conversion
- 2016
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Ingår i: Swedish Microwave Days March 15-16, 2016, Linköping, Sweden. ; , s. 53-
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Konferensbidrag (refereegranskat)abstract
- THz spectroscopy appears to be a valuable tool for gas sensing in “complicated” environments where conventional IR techniques may not be able to work: high dust and particleconcentrations. We also observe that existing spectral data basis and gas line models have to be updated for specific conditions in combustion and gasification processes.
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| 7. |
- Jareteg, Adam, 1989, et al.
(författare)
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Detailed simulations of heterogeneous reactions in porous media using the Lattice Boltzmann Method
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Flows though porous media are commonly found in many systems, both natural and manmade. A few examples from nature include petroleum reservoirs, soil and solid biomass where industrial applications include fuel cells, foams and packed beds. Most of these areas are still subject to both scientific and engineering challenges ranging from basic understanding to detailed optimization. A non-trivial part of the remaining challenges includes the interaction between macro-scale performance and micro-scale characteristics. For some systems, it is possible to control and tune micro-scale properties to optimize the overall performance of the application. This scenario typically manifests in the design of packed beds, especially when reactions occur within the bed. In such situations, particle shape and size distribution will affect not only the pressure drop (and hence the preferential flow paths), but also local reaction rates and thereby efficiency and selectivity. This work aims to understand and identify key design parameters that influences reactions within a packed bed, and ultimately, the overall performance of the pack- ing. Representative microstructures of packed beds are generated with a Discrete Element Method. Flow, temperature and concentration fields (cf. Figure 1) are then fully resolved using the Lattice Boltzmann Method with a first order reaction scheme at the boundaries. Residence time, flow structures and permeability of the systems are correlated to conversion and selectivity of the chemical reactions in the system. Comparisons between packings of different particle shapes and spacing serve to eluci- date phenomena involved in the process and implies design directions for macro-scale optimization.
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| 8. |
- Jareteg, Adam, 1989, et al.
(författare)
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Effects of bed aging on temperature signals from fixed-bed adsorbers during industrial operation
- 2020
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Ingår i: Results in Engineering. - : Elsevier BV. - 2590-1230. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The capacity of adsorber beds used in industrial-scale temperature-swing adsorption diminishes over time due to bed aging. Here, we present industrial data on the temperature signals from fixed-bed adsorbers using activated carbon designed to remove benzene and other impurities from the gas produced in biomass gasification. The aging of the adsorber beds proceeds due to irreversible adsorption of trace species and manifests itself via two simultaneous effects: a decrease in the availability of active adsorption sites over time and an increase in the overall thermal mass of the bed. Both effects tend to dampen the temperature response of the beds during operation, implying that they are easily confounded. Model descriptions of bed aging should account for both effects.
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| 9. |
- Jareteg, Adam, 1989, et al.
(författare)
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Finely resolved numerical simulations of reactive flow in porous media
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A wide variety of scientific and engineering challenges involve flows through porous media. Applications range from flow through natural porous systems, such as petroleum reservoirs, soil and biomass char particles, to flows through artificially created porous systems such as packed beds, fuel cells, foams and membranes. In both natural and artificial systems, the microscale characteristics of the media can often, to different degrees, be controlled to optimize the macroscale performance of the application. The problem is then to find the optimal configuration of the porous system. This works aims to increase the understanding of which design parameters of a packed bed that influence the performance of homo-and heterogeneous reactions inside the bed.The flow, temperature and concentration fields in representative microstructures of various packed bed configurations are fully resolved in numerical simulations employing the Lattice Boltzmann Method (LBM), where homo-and heterogeneous chemistry is simultaneously accounted for. Detailed information about the flow structures, permeability and flow paths through the system is retrieved and correlated to the conversion and selectivity of the chemical reactions in the system. The dependence of a reactive porous system on different packing parameters, such as particle shape, spacing, and packing inhomogeneities is elucidated, and the implications for achieving optimal performance in a variety of different porous media are discussed.
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| 10. |
- Jareteg, Adam, 1989, et al.
(författare)
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Industrial-scale benzene adsorption: assessment of a baseline one-dimensional temperature swing model against online industrial data
- 2020
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 59:26, s. 12239-12249
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Tidskriftsartikel (refereegranskat)abstract
- Existing models for industrial gas cleaning via temperature-swing adsorption are typically validated against laboratory-scale test units, while industrial cases involve units that are significantly larger, operate with complex gas mixtures, and are cycled for long times. The extent up to which existing model formulations are applicable in industrial units is not well established. Here, we compare simulations with a baseline 1D model at an industrial scale to the online temperature data from steam-regenerated adsorbers in a 32 MW biomass gasification plant. Adsorption of benzene is described using the Dubinin–Radushkevich isotherm, and steam may condense/evaporate but not adsorb. The simulations reproduce the main trends in the industrial data, meaning that they can be used to assess dynamic properties that are not measured, such as the amounts of adsorbates and water. Additional model development is however needed to better represent the effects of complex gas mixtures and water transport and evaporation inside the beds.
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