SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Thunman Henrik 1970) "

Sökning: WFRF:(Thunman Henrik 1970)

  • Resultat 1-50 av 232
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Keller, Martin, 1985, et al. (författare)
  • Investigation of Natural and Synthetic Bed Materials for Their Utilization in Chemical Looping Reforming for Tar Elimination in Biomass-Derived Gasification Gas
  • 2014
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 28:6, s. 3833-3840
  • 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
  •  
2.
  • Alamia, Alberto, 1984, et al. (författare)
  • Design of an integrated dryer and conveyor belt for woody biofuels
  • 2015
  • Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 77, s. 92-109
  • 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.
  •  
3.
  • Bidgoli, Hosein, 1987, et al. (författare)
  • Terahertz Spectroscopy for Real-Time Monitoring of Water Vapor and CO Levels in the Producer Gas From an Industrial Biomass Gasifier
  • 2014
  • Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 4:6, s. 722-733
  • 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.
  •  
4.
  • Cherednichenko, Serguei, 1970, et al. (författare)
  • Online Detection of H2O and CO in the Humid Raw Gas from the Gasifier Using Terahertz Spectroscopy
  • 2013
  • Ingår i: ICPS, 13 International Conference on Polygeneration Strategies, Sept.5-13, Vienna, Austria. - 9783950275483 ; , s. 51-58
  • 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).
  •  
5.
  • Cherednichenko, Serguei, 1970, et al. (författare)
  • Terahertz Gas Spectrometer
  • 2014
  • Ingår i: Swedish Microwave Days March 11-12, 2014, Gothenburg, Sweden.
  • 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.
  •  
6.
  • Cherednichenko, Serguei, 1970, et al. (författare)
  • Terahertz Spectroscopy Instrumentation for Thermal Bio-Mass Conversion
  • 2016
  • Ingår i: Swedish Microwave Days March 15-16, 2016, Linköping, Sweden. ; , s. 53-
  • 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.
  •  
7.
  • Jareteg, Adam, 1989, et al. (författare)
  • Detailed simulations of heterogeneous reactions in porous media using the Lattice Boltzmann Method
  • 2018
  • 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.
  •  
8.
  • Jareteg, Adam, 1989, et al. (författare)
  • Effects of bed aging on temperature signals from fixed-bed adsorbers during industrial operation
  • 2020
  • Ingår i: Results in Engineering. - : Elsevier BV. - 2590-1230. ; 8
  • 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.
  •  
9.
  • Jareteg, Adam, 1989, et al. (författare)
  • Finely resolved numerical simulations of reactive flow in porous media
  • 2018
  • 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.
  •  
10.
  • Jareteg, Adam, 1989, et al. (författare)
  • Industrial-scale benzene adsorption: assessment of a baseline one-dimensional temperature swing model against online industrial data
  • 2020
  • Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 59:26, s. 12239-12249
  • 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.
  •  
11.
  • Jareteg, Adam, 1989, et al. (författare)
  • Investigation of steam regeneration strategies for industrial-scale temperature-swing adsorption of benzene on activated carbon
  • 2021
  • Ingår i: Chemical Engineering and Processing: Process Intensification. - : Elsevier BV. - 0255-2701. ; 167
  • Tidskriftsartikel (refereegranskat)abstract
    • Large-scale separation of substances present at low concentrations is readily performed by adsorption in packed beds that requires recurring energy-intensive regeneration of the adsorbent. The present work uses numerical simulations previously developed for industrial-scale packed-bed benzene sorption on activated carbon with temperature-swing regeneration by steam to investigate the influence of steam properties and regeneration strategy on total energy performance and breakthrough behaviour. It is shown that using saturated steam lowers both the steam mass and energy consumption during regeneration of a fixed amount of benzene, whereas using superheated steam returns the bed to a more fresh-like state after each regeneration stage. The most promising variation tried implies a 19% reduction in the energy consumption. Furthermore, the importance of accounting for the real industrial cycling conditions in the optimization of packed-bed adsorbers is highlighted. It is shown that the participation of different sections of the bed during adsorption varies with the regeneration strategy, but is never as localized as predicted from a model for a fresh bed without cycling. Finally, the present results also show that the effluent purity attained during regeneration increases when high-temperature saturated steam is used, e.g. a 60-degree increase in steam temperature raises the purity by 11%.
  •  
12.
  • Jareteg, Adam, 1989, et al. (författare)
  • Packed-Bed Reactor Characterization of Steam-Regenerated Solvent Adsorbers for Raw-Gas Cleaning
  • 2017
  • Ingår i: Proceedings of the 14th International Conference Multiphase Flow in Industrial Plant.
  • Konferensbidrag (refereegranskat)abstract
    • Packed beds with activated carbon is a commonly used technology for removing unwantedsubstances from a process stream. To better understand how such beds operate and in orderto optimize their design and operation, one-dimensional models are typically employed.The multiphase aspects of these systems are typically neglected due to their complexity,even though regeneration with steam creates a liquid phase that may trickle through thebed, thereby effectively transporting heat and mass. This paper investigates andcharacterizes the differences in transport of gas and liquid in a representative packed bedthrough comprehensive three-dimensional numerical simulations. In addition, the effect ofheterogeneities in the packing of the bed on the transport of both phases is also investigated.It is confirmed that the dispersion of air may be well described by a conventional one-dimensional model, but that the dispersion of water requires an additional effort. It is alsofound that the system orientation significantly influences the water flow and that non-idealpacking has strong effects on the residence time distribution for both phases.
  •  
13.
  • Larsson, Anton, 1984, et al. (författare)
  • Experimental and Numerical Investigation of the Dynamics of Loop Seals in a Large-Scale DFB System under Hot Conditions
  • 2015
  • Ingår i: AICHE Journal. - : Wiley. - 1547-5905 .- 0001-1541. ; 61:11, s. 3580-3593
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigate the dynamics of the loop seals in a large-scale dual fluidized bed (DFB) system as a function of variations in the flux of the bed material through the seal and changes in the bed material density. These investigations are performed numerically with a computational fluid dynamics (CFD) model and experimentally for the loop seals of the Chalmers 2-4 MWth DFB gasifier. Both experiments and simulations show that more of the aeration gas leaves the loop seal in the direction of the solids when a low-density bed material (silica) is used rather than a high-density one (bauxite). The simulations also reveal homogeneous fluidization in a vertical connection to the loop seal, whereas an inclined connection yields heterogeneous fluidization. The minor discrepancies between the experiments and simulations with silica are attributed to particle agglomeration, and it is proposed that CFD models applied to loop seals should account for this phenomenon.
  •  
14.
  • Li, Tian, et al. (författare)
  • A fast-solving particle model for thermochemical conversion of biomass
  • 2020
  • Ingår i: Combustion and Flame. - : Elsevier BV. - 1556-2921 .- 0010-2180. ; 213, s. 117-131
  • Tidskriftsartikel (refereegranskat)abstract
    • Computational fluid dynamics (CFD) simulations of large-scale furnaces or reactors for thermal conversion of solid fuels remains challenging partially due to the high computational cost related to the particle sub-models. Owing to the thermally thick nature, it is particularly expensive to simulate the conversion of large fuel particles such as biomass particles. To address this issue, a fast-solving particle model was developed in this work with special attention to the computational efficiency. The model spatially discretizes a fuel particle in one homogenized dimension. The conversion process of the fuel particle is treated as a reactive variable-volume one-dimensional transient heat conduction problem. The model also utilizes several features that are typically found in sharp interphase-based models to reduce the computational cost. Validation of the model was carried out by comparing with experimental results under both pyrolysis and combustion conditions. The accuracy and computational efficiency of the model was thoroughly examined by varying the degrees of temporal and spatial discretization. It was found that the model well predicted pyrolysis and combustion of a single biomass particle within a broad range of temporal and spatial discretization. The time used to simulate the conversion of a biomass particle using the developed model can be more than one order of magnitude smaller than the conversion process itself. It was also revealed that a well-predicted conductive heat transfer inside the particle is essential for a precise simulation of the drying and devolatilization process. The char conversion process, however, is less sensitive to the external heat transfer as it is mainly controlled by the mass diffusion process. Further studies showed that a time step of 1×10−3 s and a spatial discretization of 20 cells were sufficient for simulating the conversion of typical fuel particles in grate-fired and fluidized-bed furnaces. We also demonstrated that when the particle model was implemented in a CFD solver, only 2.2% of computational overhead was introduced by the model. As the model can efficiently employ fixed time stepping, optimal load balancing during parallel computing of many simultaneous conversion processes becomes trivial. This performance opens up new possibilities for treating fuel polydispersity in Eulerian CFD simulations of biomass conversion.
  •  
15.
  • Maggiolo, Dario, 1985, et al. (författare)
  • Self‐Cleaning Surfaces for Heat Recovery During Industrial Hydrocarbon‐Rich Gas Cooling: An Experimental and Numerical Study
  • 2019
  • Ingår i: AICHE Journal. - : Wiley. - 1547-5905 .- 0001-1541. ; 65:1, s. 317-325
  • Tidskriftsartikel (refereegranskat)abstract
    • The cooling of hydrocarbon-rich gases in industrial processes often leads to severe fouling, which impedes heat recovery, restricts operative conditions and increases maintenance costs. In the present work, we investigate whether self-cleaning surfaces represent a possible solution to overcome this technological bottleneck. Hydrophilic and hydrophobic treatments of compact heat exchanger plates are experimentally and numerically investigated during cooling of syngas produced from biomass gasification. The experimental evidences related to the operation of heat exchanger plates are assessed first, and a deeper insight into the relevant phenomena is thereafter obtained by performing numerical simulations. Our analysis identifies the hydrophobic treatment as the most promising solution and unveils the induced self-cleaning mechanism: the formation of small-sized and movable condensed droplets that enhance the collection and removal of gas impurities. These findings open up new routes towards the development of cheaper, more efficient and sustainable gas cooling systems.
  •  
16.
  • Maggiolo, Dario, 1985, et al. (författare)
  • Two-phase flow patterns and condensation on wetted surfaces for innovative self-cleaning heat exchangers: experiments and numerics
  • 2018
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Fouling is a common and pervasive problem in industrial processes that involve the cooling of hydrocarbon-rich gas mixtures and and it is considered responsible for 1%÷2.5% of the global anthropogenic emissions of CO2. One of the major drawbacks related to fouling is that it impedes heat recovery and thereby it considerably limits the efficiency of many industrial processes. We experimentally and numerically have investigated whether self-cleaning surfaces of heat exchangers represent a possible solution to overcome this technological bottleneck. Hydrophilically and hydrophobically treated corrugated plates of heat exchangers have been experimentally tested in a 2 MW th research-gasifier and their capabilities to resist fouling have been evaluated. Results revealed that hydrophobically treated surfaces exhibit good anti-fouling and self-cleaning properties. By means of numerical Lattice-Boltzmann-based simulations we then unveiled the self-cleaning phenomenon induced by the wetted surfaces: with a similar mechanism to lotus-leaves, small and motile condensed water droplets are able to collect and remove impurities present in the gas and prevent surfaces fouling. Condensation, two-phase flows patterns formation and droplets coalescence all contribute to promote or weaken the self-cleaning effects. Therefore, numerical simulations have been finally used to identify the main mass and heat transport mechanisms that affect self-cleaning and the optimal operative conditions of the heat exchangers.
  •  
17.
  • Ström, Henrik, 1981, et al. (författare)
  • A computationally efficient particle submodel for CFD-simulations of fixed-bed conversion
  • 2013
  • Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 112:SI, s. 808-817
  • Tidskriftsartikel (refereegranskat)abstract
    • Fixed-bed conversion is one of the standard methods for conversion of biofuels. However, in several cases the performance observed in applications of fixed-bed conversion of biomass and waste is far from optimal. Mathematical modeling using computational fluid dynamics (CFD) has a large potential to assist in the optimization of the fuel conversion processes, with regard to parameters such as burnout, emissions, fuel flexibility and material wear. To this end, computationally efficient models that can handle the most important features of the fuel conversion processes are needed.In the present work, a model is derived for the first conversion stages of a woody biofuel: drying and devolatilization in an inert atmosphere. The model predictions are compared to experimental data and to the predictions of similar models of higher and lower degrees of computational complexity. It is shown that the proposed model is able to predict the correct drying and devolatilization behavior by using a small number of variables and a relatively coarse resolution of the particle interior. It is also shown that a simpler model cannot accurately describe the conversion processes as observed in experiments. Moreover, by using a shrinking-core model to describe the char combustion, the particlemass loss can be predicted correctly also during this phase. Finally, it is outlined how the current model can be extended to include effects on spatial scales significant to that of the fuel bed, such as bedcollapses and channeling.
  •  
18.
  • Ström, Henrik, 1981, et al. (författare)
  • CFD simulations of biofuel bed conversion: A submodel for the drying and devolatilization of thermally thick wood particles
  • 2013
  • Ingår i: Combustion and Flame. - : Elsevier BV. - 1556-2921 .- 0010-2180. ; 160:2, s. 417-431
  • Tidskriftsartikel (refereegranskat)abstract
    • Biomass can be converted into heat and power in fixed or fluidized fuel beds. Even though the use of these combustion techniques is widespread, detailed knowledge of the combustion behaviors in such beds, which could be used to optimize performance (especially that of fixed-bed boilers), is lacking. Computational fluid dynamics (CFD) is useful in the optimization and in obtaining detailed knowledge of the fuel conversion process, regarding parameters such as burnout, emissions, fuel flexibility, and material wear. However, for such simulations to be viable, computationally efficient models that can handle the most important features of the fuel conversion processes are needed.In the current work, a model is derived for the drying and devolatilization of moist wood particles in an inert atmosphere. The model is compared to three sets of experimental data from two independent research groups. The proposed model predicts drying and devolatilization behavior in agreement with the experimental data using only a few variables. By describing the heat of devolatilization as a linear function of temperature, excellent predictions of the particle core temperature (and thereby, of the rate of devolatilization) are obtained after the drying is complete. For beech and poplar, the average heat of devolatilization is approximately 100 kJ/kg.The implementation of the particle submodel into a CFD code is described in detail. The submodel can predict 2–10 seconds of real time per second of computation, which is shown to be sufficient to treat a bed of particles in 2D or 3D. The discussion addresses how effects on the multi-particle scale, such as local collapses of a fixed fuel bed, can be dealt with in the most efficient manner.
  •  
19.
  • Ström, Henrik, 1981, et al. (författare)
  • Challenges and opportunities in the Eulerian approach to numerical simulations of fixed-bed combustion of biomass
  • 2015
  • Ingår i: Procedia Engineering. - : Elsevier BV. - 1877-7058 .- 1877-7058. ; 102, s. 1573-1582
  • Konferensbidrag (refereegranskat)abstract
    • Fixed-bed combustion is a commonly employed technique for commercial production of heat and power from biomass and waste. In this work, the modeling challenges and opportunities within the Eulerian (averaged) approach to simulations of fixed-bed combustion systems are investigated in relation to the challenges faced within the biomass combustion area today. It is shown how the particle models for use with the Eulerian approach to numerical simulations of fixed-bed combustion should be constructed to make possible accurate predictions of the volatile release, particle heat transfer and ash slagging phenomena. A number of numerical challenges related to the accuracy and efficiency of Eulerian models for fixed-bed conversion are also identified and possible strategies to remedy them are proposed.
  •  
20.
  • Ström, Henrik, 1981, et al. (författare)
  • Development of a particle submodel for CFD-simulations of fixed-bed combustion
  • 2012
  • Ingår i: Proceedings of the 4th International Conference on Applied Energy (ICAE2012). ; Paper ID: ICAE2012-A10287
  • Konferensbidrag (refereegranskat)abstract
    • Fixed-bed conversion is one of the standard methods for conversion of biofuels. However, in several cases the performance observed in applications of fixed-bed conversion of biomass and waste is far from optimal. Mathematical modeling using computational fluid dynamics (CFD) has a large potential to assist in the optimization of the fuel conversion processes, with regard to parameters such as burnout, emissions, fuel flexibility and material wear. To this end, computationally efficient models that can handle the most important features of the fuel conversion processes are needed.In the present work, a model is derived for the drying and devolatilization of a moist wood particle in an inert atmosphere. This model is compared to experimental data and discussed in relation to similar models of higher and lower degrees of computational complexity. It is shown that the proposed model is able to predict the correct drying and devolatilization behavior by using only a small number of variables. It is also outlined how this model can be extended to include the char combustion and effects on the multi-particle scale, such as local collapses of the fuel bed.
  •  
21.
  • Thunman, Henrik, 1970, et al. (författare)
  • Advanced biofuel production via gasification – lessons learned from 200 man-years of research activity with Chalmers’ research gasifier and the GoBiGas demonstration plant.
  • 2018
  • Ingår i: Energy Science and Engineering. - : Wiley. - 2050-0505. ; 6:1, s. 6-34
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents the main experiences gained and conclusions drawn from the demonstration of a first-of-its-kind wood-based biomethane production plant (20-MW capacity, 150 dry tonnes of biomass/day) and 10 years of operation of the 2–4-MW (10–20 dry tonnes of biomass/day) research gasifier at Chalmers University of Technology in Sweden. Based on the experience gained, an elaborated outline for commercialization of the technology for a wide spectrum of applications and end products is defined. The main findings are related to the use of biomass ash constituents as a catalyst for the process and the application of coated heat exchangers, such that regular fluidized bed boilers can be retrofitted to become biomass gasifiers. Among the recirculation of the ash streams within the process, presence of the alkali salt in the system is identified as highly important for control of the tar species. Combined with new insights on fuel feeding and reactor design, these two major findings form the basis for a comprehensive process layout that can support a gradual transformation of existing boilers in district heating networks and in pulp, paper and saw mills, and it facilitates the exploitation of existing oil refineries and petrochemical plants for large-scale production of renewable fuels, chemicals, and materials from biomass and wastes. The potential for electrification of those process layouts are also discussed. The commercialization route represents an example of how biomass conversion develops and integrates with existing industrial and energy infrastructures to form highly effective systems that deliver a wide range of end products. Illustrating the potential, the existing fluidized bed boilers in Sweden alone represent a jet fuel production capacity that corresponds to 10% of current global consumption.
  •  
22.
  •  
23.
  • Zhao, Ke, 1979, et al. (författare)
  • Control of the solids retention time by multi-staging a fluidized bed reactor
  • 2017
  • Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 167, s. 171-182
  • Tidskriftsartikel (refereegranskat)abstract
    • Fluidized bed reactors are often operated with particles of different size and density present simultaneously (e.g. inert bed material and fuel particles in fluidized bed combustion, or catalyst particles and polymer particles in fluidized bed polymerization). This paper presents a general concept to separate a single fluidized bed reactor into two reaction zones by introducing a primary chamber in the bed where flotsam particles are fed and spend a certain initial residence time. The feasibility of the concept is experimentally proven in a fluid-dynamically down-scaled unit, both in terms of functionality (ability to maintain two separate reaction regions and to avoid backflow from the secondary to the primary region of the solids fed) and of operability (ability to control the residence time distribution of the solids fed in the primary chamber through operational parameters such as pressure and bed height). Numerical simulations show that the residence time distribution is sensitive to the degree of segregation in the primary chamber, and that the heat transfer between the two reaction regions by means of bulk solids mixing is still sufficient to sustain an endothermic process in one zone by an exothermic process in the other.
  •  
24.
  • Ahlström, Johan, 1990, et al. (författare)
  • Bark as feedstock for dual fluidized bed gasifiers. Operability, efficiency, and economics
  • 2019
  • Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 43:3, s. 1171-1190
  • Tidskriftsartikel (refereegranskat)abstract
    • The demand for biofuels and biochemicals is expected to increase in the future, which will in turn increase the demand for biomass feedstock. Large gasification plants fueled with biomass feedstock are likely to be a key enabling technology in a resource-efficient, bio-based economy. Furthermore, the costs for producing biofuels and biochemicals in such plants could potentially be decreased by utilizing inexpensive low-grade residual biomass as feedstock. This study investigates the usage of shredded tree bark as a feedstock for the production of biomethane in the GoBiGas demonstration plant in Gothenburg, Sweden, based on a 32 MWth industrial dual fluidized bed gasification unit. The plant was operated with bark feedstock for 12 000 hours during the period 2014 to 2018. Data from the measurement campaign were processed using a stochastic approach to establish the plant's mass and energy balances, which were then compared with operation of the plant with wood pellets. For this comparison, an extrapolation algorithm was developed to predict plant performance using bark dried to the same moisture content as wood pellets, ie, 8%w.b. Plant operation with bark feedstock was evaluated for operability, efficiency, and feedstock-related cost. The gas quality achieved during the test period was similar to that obtained for operation with wood pellets. Furthermore, no significant ash sintering or agglomeration problems were observed more than 750 hours of operation. The calculated biomass-to-biomethane efficiency is 43% to 47% (lower heating value basis) for operation with wet bark. However, the predicted biomass-to-biomethane efficiency can be increased to 55%–65% for operation with bark feedstock dried to 8% moisture content, with corresponding feedstock costs in the range of 24.2 to 32.7 EUR/MWh; ie, a cost reduction of about 40% compared with wood pellets.
  •  
25.
  • Alamia, Alberto, 1984, et al. (författare)
  • Efficiency Comparison of Large-Scale Standalone, Centralized, and Distributed Thermochemical Biorefineries
  • 2017
  • Ingår i: Energy Technology. - : Wiley. - 2194-4296 .- 2194-4288. ; 5:8, s. 1435-1448
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.We present a comparison of three strategies for the introduction of new biorefineries: standalone and centralized drop-in, which are placed within a cluster of chemical industries, and distributed drop-in, which is connected to other plants by a pipeline. The aim was to quantify the efficiencies and the production ranges to support local transition to a circular economy based on biomass usage. The products considered are biomethane (standalone) and hydrogen/biomethane and sustainable town gas (centralized drop-in and distributed drop-in). The analysis is based on a flow-sheet simulation of different process designs at the 100MWbiomass scale and includes the following aspects: advanced drying systems, the coproduction of ethanol, and power-to-gas conversion by direct heating or water electrolysis. For the standalone plant, the chemical efficiency was in the range of 78-82.8% LHVa.r.50% (lower heating value of the as-received biomass with 50% wet basis moisture), with a maximum production of 72MWCH4 , and for the centralized drop-in and distributed drop-in plants, the chemical efficiency was in the range of 82.8-98.5% LHVa.r.50% with maximum production levels of 85.6MWSTG and 22.5MWH2 /51MWCH4 , respectively. It is concluded that standalone plants offer no substantial advantages over distributed drop-in or centralized drop-in plants unless methane is the desired product.
  •  
26.
  • Alamia, Alberto, 1984, et al. (författare)
  • Fuel Quality Analysis for Biogas Utilization in Heavy Duty Dual Fuel Engines
  • 2012
  • Ingår i: World BioEnergy 2012 - conference in Jönköping , May 2012. ; , s. 1-
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The perspective of using gas form biomass gasification as fuel for dual fuel (DF) engines, without refine it all the way to synthetic natural gas (SNG) has been investigated. The initial gas from gasification contains of a blend of various components which are not commonly present in natural gas (NG). The operability of these components in a heavy duty DF engine has been assessed and compared to those of NG. Three parameters have been used to define the quality of the fuel: Lower Heating Value (LHV), Methane Number (MN) and Lower Flammability Limit (LFL).
  •  
27.
  • Alamia, Alberto, 1984, et al. (författare)
  • Fuel Quality Analysis for Biogas Utilization in Heavy Duty Dual Fuel Engines
  • 2012
  • Ingår i: 20th European Biomass conference & exhibition - Milan -June 2012. - 9788889407547 ; , s. 5-
  • Konferensbidrag (refereegranskat)abstract
    • Internal combustion engines using oil-derived fuels are dominating the heavy transportation sector today. However, the climate issue and security of supply drive the development towards new fuels and engine technologies. In the short term, Natural Gas (NG) is expected to have a dominant role, due to its high availability and a favourable H/C ratio. Thereafter, it is expect an introduction of biofuels of second and third generations. In this scenario the engine suppliers need to develop engines for various fuels of both fossil and renewable origin. One possibility is the Dual Fuel engine (DF), which uses a Diesel pilot to ignite a gas mixture and, it can be used for natural gas of various qualities as well as synthetic natural gas (SNG). To obtain significant share of second and third generation biofuels into the transportation sector a key process is gasification of the raw solid biomass to gas, as it can offer high production capacity and high efficiency. One interesting biofuel is SNG and at present there are a number of projects focusing on SNG production through gasification of biomass to be fed to the NG grid. However, this is a rather advanced and several stage process. The initial gas from the gasification before the gas is upgraded to CH4 (SNG) contains of a blend of various gas components such as H2, CO, CO2, CH4 and fractions of C2H2, C2H4, C3H6, and C3H8, as well as, longer hydrocarbons. The upgrading takes place in many process steps, where each step involves a cost and loss of energy. The question raised is if there are more efficient routs to introduce biomass derived gas than refine it all the way to SNG, from a well to wheel (WTW) perspective? The first step in such an analysis is to investigate how different gas mixtures could meet emission limits, together with the required performance of efficiency and load. This issue has been addressed in this work, where the operability in DF engines using gaseous fuels with a variation in fuel quality has been investigated. The operability has a key role in the optimization of the WTW efficiency, since it influences both the production process and the combustion in the engine. The definition of fuel quality for gaseous fuels to be used in gas engines is still not in place and proper legislation and standards are not available. Here, three parameters which are fundamental for a proper combustion in a DF engine: the Methane Number (MN), the Lower Flammability Limit (LFL) and the Lower Heating Value (LHV) have been studied. All parameters influence the combustion performance in the DF engine of the Port-injected type, which is more sensitive to the fuel quality than the Direct-injected type. The components available from biomass gasification were evaluated together with those from different NG compositions on the European market. Specific relations between the composition and fuel quality parameters have been derived, which can be used as starting point for future well to wheel analysis.
  •  
28.
  • Alamia, Alberto, 1984, et al. (författare)
  • Hydrogen from Biomass Gasification for Utilization in Oil Refineries
  • 2012
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • If taxes fees and other restriction on fossil fuels are not considered the cost for the fuels produced from biomass gasification will still be higher than that of oil-based fuels or natural gas for next decades.Nevertheless, there is room for other application of the biomass gasification followed by gas upgrading rather than fuel production. The proposed idea is a gasification-upgrading process optimized for hydrogen production, intended for the integration in an oil refinery. Driving forces for the introduction of this process are; 1, thedependency of the crude oil price on the sulfur content, 2, making use of low temperature waste heat and 3, the possibility to utilize existing infrastructure to introduce renewable energy sources (RES) in the refinery.The hydrodesulfurization of the refined petroleum productsrequires pure hydrogen, which is usually obtained from the one contained in the oil itself. Crude oils with unfavorable sulfur to hydrogen ratio have a lower price on the market, but they require extra hydrogen for the desulfurization process. Hence, there is roomfor introducing an extra source of hydrogen from a RES as biomass. Despite the technological challenge introduction of a new process causes, a high marginal profit can be achieved from the purchase of low price crude oil with high sulfur content.The process proposed in this work is suitable for integration, since it requires mainly low temperature heat (150 °C) which is abundant in an oil refinery and a small amount of electricity. The gasification process could then be seen as a perfect heat sink for low temperature waste heat, which otherwise usually is lost due to heatexchanging with the surrounding air.
  •  
29.
  • Alamia, Alberto, 1984, et al. (författare)
  • Performance of large-scale biomass gasifiers in a biorefinery, a state-of-the-art reference
  • 2017
  • Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 41:14, s. 2001-2019
  • Tidskriftsartikel (refereegranskat)abstract
    • The Gothenburg Biomass Gasification plant (2015) is currently the largest plant in the world producing biomethane (20 MWbiomethane) from woody biomass. We present the experimental data from the first measurement campaign and evaluate the mass and energy balances of the gasification sections at the plant. Measures improving the efficiency including the use of additives (potassium and sulfur), high-temperature pre-heating of the inlet streams, improved insulation of the reactors, drying of the biomass and introduction of electricity as a heat source (power-to-gas) are investigated with simulations. The cold gas efficiency was calculated in 71.7%LHVdaf using dried biomass (8% moist). The gasifier reaches high fuel conversion, with char gasification of 54%, and the fraction of the volatiles is converted to methane of 34%mass. Because of the design, the heat losses are significant (5.2%LHVdaf), which affect the efficiency. The combination of potential improvements can increase the cold gas efficiency to 83.5%LHVdaf, which is technically feasible in a commercial plant. The experience gained from the Gothenburg Biomass Gasification plant reveals the strong potential biomass gasification at large scale.
  •  
30.
  • Alamia, Alberto, 1984, et al. (författare)
  • Process Simulation of Dual Fluidized Bed Gasifiers Using Experimental Data
  • 2016
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 30:5, s. 4017-4033
  • Tidskriftsartikel (refereegranskat)abstract
    • Process simulation of a dual fluidized bed (DFB) gasifier is challenging, owing to the high degree of freedominherent to the operation of the double-reactor system and the complexity of the reactions therein. We propose a method forsimulation of the gasifier based on the analysis of experimental data and of the total uncertainty associated with them. The overallaim is to use data from the large amount of pilot and demonstration gasifiers in the analysis and optimization of gasification-basedprocesses. In the method proposed a set of fuel conversion variables and their associated uncertainties are calculated using astochastic approach that takes into account the effect of unclosed mass balance, incomplete characterization of the raw gascompounds and measurement errors. Subsequently, these fuel conversion variables are used to simulate the gasifier in a flowsheetmodel developed in Aspen Plus. The results include the evaluation of critical parameters, such as, gasifier efficiency, chargasification, and tar yield and their uncertainties, which depend highly on the measurement system. The method is applied todata sets derived from several measurement setups, and the results are validated with total carbon measurements. The resultsshow that detection of ≥95% of the carbon in the raw gas is necessary to maintain the uncertainty level at
  •  
31.
  • Alamia, Alberto, 1984, et al. (författare)
  • Well-to-wheel analysis of bio-methane via gasification, in heavy duty engines within the transport sector of the European Union
  • 2016
  • Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 170, s. 445-454
  • Tidskriftsartikel (refereegranskat)abstract
    • Bio-methane from biomass gasification (bio-methane) is expected to play a major role as a biofuel in the heavy transport sector, since the production process has reached the technical maturity required for large-scale exploitation, and the fact that bio-methane can be distributed through the compressed natural gas (CNG) and liquefied natural gas (LNG) supply chains. Assuming that the burning of biomass is climate-neutral, we compared the well-to-wheel (WtW) emissions from the use of bio-methane in heavy duty engines with those from currently used fossil alternatives: CNG, LNG, and diesel. The well-to-tank (WtT) analysis of bio-methane is based on the case study of the new GoBiGas plant in Gothenburg (Sweden), which is the largest bio-methane plant in the world currently in operation. Finally, tank-to-wheel (TtW) section compares three different state-of-the-art heavy duty gas engines: a spark-ignited (SI) gas engine; a dual fuel (DF) engine; and a high-pressure direct injection (HPDI) engine.The WtT emissions for compressed bio-methane (bio-CNG) and liquefies bio-methane (bio-LNG) were estimated at 21.5 [gCO2e/MJbioCNG] and 26.2 [gCO2e/MJbioLNG]. As compared to diesel the WtW emissions from bio-methane were reduced by 60-67%, 43-47%, and 64% when used in SI, DF, and HPDI engines, respectively. HPDI and DF are the most efficient technologies for the utilization of biomass, reducing emissions by 39 gCO2e and 33-36 gCO2e per MJ of biomass, respectively, compared with the diesel case, whereas the SI engine gave an emissions saving of 29-31 gCO2e.
  •  
32.
  • Atongka Tchoffor, Placid, et al. (författare)
  • Effects of Steam on the Release of Potassium, Chlorine, and Sulfur during Char Conversion, Investigated under Dual Fluidized Bed Gasification Conditions
  • 2014
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 28:11, s. 6953-6965
  • Tidskriftsartikel (refereegranskat)abstract
    • The corrosion and fouling of heat-transfer surfaces and the agglomeration of bed materials in fluidized beds are some of the ash-related problems caused by the transformation and release to the gas phase of ash-forming elements from biomass during thermochemical conversion processes. The magnitudes of these problems are largely dependent upon the release of potassium (K), chlorine (Cl), and sulfur (S) from the biomass. We investigated the effects of steam on the release of K, Cl, and S during char conversion, under conditions relevant for dual-fluidized-bed gasification (DFBG). The study was carried out with wheat straw in a laboratory-scale bubbling fluidized-bed reactor in the temperature range of 800-900 °C. The release of K, Cl, and S from wheat straw during devolatilization, char gasification, and char combustion was quantified with a mass balance that linked the masses of these elements in the wheat straw to the mass of the solid residue obtained at the end of each experiment. To facilitate analyses of the experimental results, leaching and the Brunauer-Emmett-Teller surface area measurement of the wheat straw and some of the solid residues were carried out. The results show that, during devolatilization, the release of volatile salts, e.g., KCl, is significantly limited by intraparticle diffusion resistance, owing to a compact char matrix (i.e., negligible porosity). However, during char gasification, steam renders the char less compact by expanding and/or creating new pores in the char. As a result, intraparticle diffusion resistance decreases, thereby facilitating the evaporation of volatile salts of K and S from the char matrix. The conversion of the char is also conducive to the release of char-bound K and S, especially at 900 °C. At temperatures of >800 °C, the relative proportions of the elements released and char gasified indicate that the release of K can somewhat be decoupled from the release of S and Cl by maximizing the extent of char conversion in the gasification chamber. The results also show that, during char combustion, the proportions of the char that can be combusted and the extent of the release of the elements are influenced by the extent to which the char is gasified in the gasification chamber.
  •  
33.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Bed material as a catalyst for char gasification: The case of ash-coated olivine activated by K and S addition
  • 2018
  • Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 224, s. 85-93
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, the ability of an ash-coated olivine to catalyze the steam gasification of biomass-derived char is investigated in a laboratory reactor. The olivine investigated is a sample from the Chalmers dual fluidized bed gasifier and it has been activated by the in-bed addition of S and K 2 CO 3 . The char and bed material samples were analyzed by Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS). It is shown that the ash layer coating of the olivine can catalyze the steam gasification of char by transferring catalytic potassium (K) to the char particles. The mobilities of the catalytic species from the olivine ash-layer are discussed. This work furthers the current understanding of the catalytic activities of ash-coated bed material particles during the thermochemical conversion of carbonaceous feedstocks in fluidized beds. In addition, it complements the existing literature on catalytic bed materials, which to date have focused on tar removal and improving gas quality.
  •  
34.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Behaviour of biomass particles in a large scale (2-4MWth) bubbling bed reactor
  • 2015
  • Ingår i: WIT Transactions on Engineering Sciences- Computational methods in multiphase flow VIII. - 9781845649463 ; 89, s. 151-160
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Biomass is regarded as an interesting fuel for energy-related processes owing to its renewable nature. However, the high volatile content of biomass adds a number of difficulties to the fuel conversion and process operation. In the context of fluidized bed reactors, several authors have observed that devolatilizing fuel particles tend to float on the surface of a gas-fluidized bed of finer solids. This behaviour, known as segregation, leads to undesired effects such as poor contact between volatiles and bed material. Previous investigations on segregation of gas-emitting particles in fluidized beds are conducted in small units and they are often operated at rather low gas velocities, typically between the minimum fluidization velocity (umf) and 2·umf. Therefore, it is not known to what extent such results are of relevance for industrial scale units and for higher fluidization velocities that are commonly used in large bubbling beds. In this work the behaviour of biomass particles in a large scale bubbling bed reactor is investigated. Tests were conducted at a wide range of fluidization velocities with three different bed materials of varying particle size and density. The fuel was wood pellets and the fluidization medium was steam, which makes the findings relevant for indirect gasification, chemical looping combustion (CLC) and bubbling bed combustion applications. The experiments were recorded by means of a digital video camera and the digital images were subsequently analysed qualitatively. The results show high level of segregation at fluidization velocity up to 3.5umf. Beyond this point fuel mixing was significantly enhanced by increasing fluidization velocities. At the highest fluidization velocity tested (i.e. >8umf), a maximum degree of mixing was achieved.
  •  
35.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Comparing Active Bed Materials in a Dual Fluidized Bed Biomass Gasifier: Olivine, Bauxite, Quartz-Sand, and Ilmenite
  • 2016
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 30:6, s. 4848-4857
  • Tidskriftsartikel (refereegranskat)abstract
    • Active bed materials are in this work investigated for in situ gas upgrading of biomass-derived gas. Previous research on in situ gas upgrading has focused on assessing gas quality, in terms of the concentrations of tar and permanent gases. Other aspects of fuel conversion, such as char conversion and the impact of oxygen transport on the final gas, are not as well documented in the literature on gasification. In this paper, the overall biomass conversion in a dual fluidized bed biomass gasifier is investigated in the presence of the catalytic material olivine and the alkali-binding material bauxite. The impact of these materials on fuel conversion is described as the combination of four effects, which are induced by the bed material: thermal, catalytic, ash-enhanced catalytic effect, and oxygen transport. Quartz-sand and ilmenite are here used as the reference materials for the thermal and the oxygen transport effects, respectively. Olivine and bauxite show activity toward tar species compared to quartz-sand. After 1 week of operation and exposure to biomass ash, the activities of olivine and bauxite toward tar species increase further, and the water gas shift reaction is catalyzed by both materials. Additionally, bauxite shows a stronger ability to increase char conversion than olivine. Under the conditions tested, olivine and bauxite have some degree of oxygen transport capacity, which is between those of quartz-sand and ilmenite. The oxygen transport effect is higher for bauxite than for olivine; nevertheless, the catalytic activities of the materials result in higher yields of H-2 than in a similar case with quartz-sand. The implications of the findings for the operation of dual fluidized bed gasifiers are discussed.
  •  
36.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Experience of more than 1000 h of operation with oxygen carriers and solid biomass at large scale
  • 2017
  • Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 190, s. 1174-1183
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents an overview of the experience gained from operating a dual fluidized bed system with oxygen carriers and biomass for more than 1000 h. The tests were carried out in the Chalmers boiler/gasifier loop (with inputs of 12 MWth and 2–4 MWth, respectively), which is 2–4 orders of magnitude larger than most existing CLC units. Coarse biomass particles (i.e., commercial wood pellets) were fed as fuel onto the surface of a mild fluidized bed. This limits significantly the contacts between the volatiles and the oxygen carrier particles, as the flotsam fuel tends to remain on the surface of the bed while the volatiles are released. The oxygen carrier materials tested were ilmenite and a manganese ore. The influences on biomass conversion of fluidization velocity, fuel feeding rate, and circulation rate of the bed material were investigated. Both bed materials efficiently transported oxygen between the reactors, achieving up to 60% combustion of the gases released in the reactor at a relatively low temperature, i.e., 830 °C. The ilmenite outperformed the manganese ore under the conditions investigated. With oxygen carriers, the yield of hydrocarbons heavier than benzene was in the range of 10–11 g/N m3, which was 70% (w/w) lower than that obtained in a reference case with silica-sand as the bed material. The conversion of volatile species to CO2 was limited by gas-solids mixing, which could be enhanced by altering the fluidization velocity. The circulation rate of the bed material and the fuel feeding rate were found to have important influences on the rate of char gasification. Given the relatively low operating temperature and the simple reactor design, relatively high conversion of biomass by the oxygen carriers was achieved. There is scope for further optimization of the operating conditions, to achieve higher conversion levels, which would enable the implementation of CLC of biomass on a large scale. © 2017 Elsevier Ltd
  •  
37.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Experimental Investigation of Volatiles-Bed Contact in a 2-4 MWth Bubbling Bed Reactor of a Dual Fluidized Bed Gasifier
  • 2015
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 29:10, s. 6456-6464
  • Tidskriftsartikel (refereegranskat)abstract
    • The use of catalytic bed materials in fluidized bed gasifiers represents a promising primary measure to decrease the tar content of biomass-derived raw gas. For effective application of such in-bed catalysts, extensive contact must be established between the volatile matter released from the fuel particles and the bed material. However, the extent of the contact and, consequently, the potential of in-bed tar removal techniques are not well understood. In this work, the fraction of volatile matter that interacts with the bed in a large (i.e., throughput of 300-400 kg/h biomass) bubbling bed gasifier is quantified experimentally and the effect of fluidization velocity is investigated. The results show that a higher fluidization velocity enhances gas-solid contact, with 48-69% of the volatile matter coming in contact with the bed within the range of 6-10 times the minimum fluidization (umf).
  •  
38.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Impact of oxygen transport on char conversion in dual fluidized bed systems
  • 2015
  • Ingår i: Nordic Flame Days 2015, Copenhagen.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • In the context of thermochemical conversion of solid fuels in dual fluidized bed (DFB) reactors, oxygen carrier bed materials have been found to enhance the rate of char gasification.Char gasification is typically the rate limiting step in the conversion process, which plays a role on the performance of the overall process and constrains the design of the reactor. The quantity of oxygen carried by the bed material in relation to the fuel feeding rate is likely to influence char conversion. This parameter is commonly characterized in literature by the oxygen-carrier-to-fuel ratio (ϕ), and it can be adjusted by either varying the fuel feed and/or the circulation rate of bed material in the DFB. The residence time of the fuel is typically altered by these changes, which results in an unclear role of the oxygen-carrier-to fuel ratio on the final char conversion. The present work investigates the impact of oxygen transport on char conversion in the 2-4 MWth DFB gasifier at Chalmers University of Technology. An iron ore is used as oxygen carrier and steam as fluidizing agent. A parametric study is conducted, in which a wide range of oxygen-carrier-to-fuel ratio (ϕ=3-12) are achieved by varying fuel flow and bed material circulation. Char conversion is calculated on the basis of gas analysis and mass balance calculations. The results confirm that oxygen transport enhances char conversion, in line with previous research in smaller units. Both fuel feed and circulation of bed material had an impact on the final char conversion under the conditions tested, which differs from previous investigations. For a given residence time of the fuel particles in the reactor, char conversion was found proportional to the oxygen-carrier-to-fuel ratio.
  •  
39.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Influence of in-bed catalysis by ash-coated olivine on tar formation in steam gasification of biomass
  • 2018
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 32:9, s. 9592-9604
  • Tidskriftsartikel (refereegranskat)abstract
    • The use of catalytic bed materials has become a state-of-the-art solution to control the concentration of tar in fluidized bed biomass steam gasifiers. Ash-coated olivine is commonly applied as bed material, owing to its relatively high catalytic activity towards tar species. However, the mechanisms and conversion pathways influenced by the ash-coated olivine when applied as an in-bed catalyst are still not well understood. The present work aims at proving that the ash-layered olivine prevents the formation of biomass-derived tar at an early stage of their formation. Tests with olivine at different stages of activation and at different temperatures are carried out in the Chalmers 2-4MWth DFB gasifier. Detailed characterization of the tar and light hydrocarbon fractions are presented and discussed in relation to the sources of aromatic species. It is concluded that the ash-coated olivine prevents the formation of aromatic tar species by promoting the steam reforming of early tar precursors. Gas-phase interactions of the early tar precursors and bed material contribute to the tar reduction observed. The results indicate that olivine interferes the cyclization routes involving C2H2 and C3 hydrocarbons.
  •  
40.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Mapping the effects of potassium on fuel conversion in industrial-scale fluidized bed gasifiers and combustors
  • 2021
  • Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 11:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Potassium (K) is a notorious villain among the ash components found in the biomass, being the cause of bed agglomeration and contributing to fouling and corrosion. At the same time, K is known to have catalytic properties towards fuel conversion in combustion and gasification environments. Olivine (MgFe silicate) used as gasifier bed material has a higher propensity to form catalytically active K species than traditional silica sand beds, which tend to react with K to form stable and inactive silicates. In a dual fluidized bed (DFB) gasifier, many of those catalytic effects are expected to be relevant, given that the bed material becomes naturally enriched with ash elements from the fuel. However, a comprehensive overview of how enrichment of the bed with alkali affects fuel conversion in both parts of the DFB system is lacking. In this work, the effects of ash-enriched olivine on fuel conversion in the gasification and combustion parts of the process are mapped. The work is based on a dedicated experimental campaign in a Chalmers DFB gasifier, wherein enrichment of the bed material with K is promoted by the addition of a reaction partner, i.e., sulfur, which ensures K retention in the bed in forms other than inactive silicates. The choice of sulfur is based on its affinity for K under combustion conditions. The addition of sulfur proved to be an efficient strategy for capturing catalytic K in olivine particles. In the gasification part, K-loaded olivine enhanced the char gasification rate, decreased the tar concentration, and promoted the WGS equilibrium. In the combustion part, K prevented full oxidation of CO, which could be mitigated by the addition of sulfur to the cyclone outlet.
  •  
41.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Shedding light on the governing mechanisms for insufficient CO and H2 burnout in the presence of potassium, chlorine and sulfur
  • 2020
  • Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 273
  • Tidskriftsartikel (refereegranskat)abstract
    • Based on the experiences of insufficient burnout in industrial fluidized bed furnaces despite adequate mixing and availability of oxidizer, the influence of potassium on CO and H2 oxidation in combustion environments was investigated. The combustion environments were provided by a laminar flame burner in a range relevant to industrial furnaces, i.e. 845 °C to 1275 °C and excess air ratios ranging from 1.05 to 1.65. Potassium, in the form of KOH, was homogeneously introduced into the hot gas environments to investigate its effect on the radical pool. To quantitatively determine key species that are involved in the oxidation mechanism (CO, H2, KOH, OH radicals, K atoms), a combination of measurement systems was applied: micro-gas chromatography, broadband UV absorption spectroscopy and tunable diode laser absorption spectroscopy. The inhibition effect of potassium on CO and H2 oxidation in excess air was experimentally confirmed and attributed to the chain-terminating reaction between KOH, K atoms and OH radicals, which enhanced the OH radical consumption. The addition of chlorine or sulfur could reduce the concentrations of KOH and K atoms and consequently eliminated the inhibition on CO and H2 oxidation. Existing kinetic mechanisms underestimate the inhibiting effect of potassium and they fail to predict the effect of temperature on CO and H2 concentration when potassium and sulfur co-exist. This work advances the need to revise existing kinetic mechanisms to fully capture the interplay of K and S in the oxidation of CO and H2 in industrial fluidized bed furnaces.
  •  
42.
  • Berguerand, Nicolas, 1978, et al. (författare)
  • Producer Gas Cleaning in a Dual Fluidized Bed Reformer using Two Catalysts
  • 2011
  • Ingår i: Compendium of the International Conference on Polygeneration Strategies11. ; , s. 9-
  • Konferensbidrag (refereegranskat)abstract
    • The most elegant method to remove tars out of producer gas from biomass gasification is catalytic hot gas cleaning. However, most catalysts are poisoned after short operation due to carbon formation or by other contaminants on their active sites. A novel technique for catalytic gas cleaning based on two interconnected fluidized beds has been investigated. The idea is to reform the tar components into useful molecules by means of a circulating catalyst, also called oxygen carrier in the following. The producer gas is cleaned in one of the reactors, referred to as the fuel reactor (FR), while it is continuously regenerated in the air reactor (AR). The two reactors are separated by loop seals in such a way that gas leakage is prevented between the reactors while solid circulation occurs. By varying the circulation rate of material in the system, the residence time in the raw gas stream and the frequency of regeneration can be adjusted. Meanwhile, the required amount of oxygen for partial oxidation of the tars is transferred. The system described here is coupled with its FR to the Chalmers 2-4 MWth biomass gasifier while the AR is fed with nitrogen-diluted air. In preliminary tests, the effect of different catalysts on both the tar content and the gas composition was investigated. Some of the tested materials do not only reform tars, they also influence the H2/CO-ratio in a beneficial manner. In this paper, comparative results based on testing with manganese and iron based catalysts are presented. Results suggest that both show satisfying ability for regeneration from carbon deposits. Higher temperature enhances tar removal during experiment with both catalysts. Moreover, the iron-based catalyst enhances water gas shift activity, which in turns impacts the total amount of produced gas. On the other hand, the manganese-based catalyst seems to express higher propensity for tar conversion. These observations elicit an interesting flexibility of the process as a judicious set of catalyst in coordination with pertinent operating conditions can be chosen to achieve desired purposes.
  •  
43.
  • Berguerand, Nicolas, 1978, et al. (författare)
  • Use of Alkali-Feldspar as Bed Material for Upgrading a Biomass-derived Producer Gas from a Gasifier
  • 2016
  • Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 295, s. 80-91
  • Tidskriftsartikel (refereegranskat)abstract
    • Gasification of biomass has strong potential for biofuels production. However, one challenge to its competitiveness is the efficient elimination of the tars present in the raw gas. The use of active bed materials in tar reforming is an appealing approach and can be employed as part of primary and/or secondary measures. Here, the activity of an alkali-feldspar [(K, Na)AlSi3O8] ore was assessed in relation to upgrading the producer gas from the Chalmers 2–4 MW indirect biomass gasifier. This material was tested in a single bubbling bed reactor previously developed for studies involving catalytic tar reforming. The bed of feldspar was fluidized with raw gas. The material was tested at three temperatures: 700 C, 800 C, and 900 C. The results indicate that alkali-feldspar shows: (1) a high potential for the Water–Gas Shift reaction even at low temperature (H2/CO 3); (2) no reduction of the methane content in the cleaned gas and net formation of methane at 900 C; (3) the elimination of most C2H2 and C3H6 already at 800 C; and (4) a striking tar selectivity, which resulted in the reformed gas having exclusively pure ring-compounds. In the same reactor set-up at 800 C, fresh olivine was comparatively less efficient than feldspar in reducing tar levels. At 900 C, the feldspar decomposed 47% excepting benzene. Moreover, it retained its mechanical integrity, withstood longer reducing periods (3 h), and displayed neither signs of agglomeration nor loss of activity, despite the formation of a carbon deposit. The deposits were readily removed by introducing an oxidizing atmosphere. Furthermore, the raw feldspar showed a low capacity for oxygen transport, advantageous in this application. Taken together, our results indicate that this material is clearly promising and warrants further investigations.
  •  
44.
  • Berguerand, Nicolas, 1978, et al. (författare)
  • Use of Nickel Oxide as a Catalyst for Tar Elimination in a Chemical-Looping Reforming Reactor Operated with Biomass Producer Gas
  • 2012
  • Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 51:51, s. 16610-16616
  • Tidskriftsartikel (refereegranskat)abstract
    • A secondary tar-cleaning process based on Chemical-Looping Reforming (CLR) was investigated for upgrading biomass producer gas, derived from the Chalmers University of Technology 2-4 MW indirect gasifier. The experiments were conducted in a bench-scale CLR reactor using a manufactured nickel oxide (NiO) catalyst. Although Ni is a well-documented and efficient steam-reforming catalyst, it is susceptible to rapid deactivation under tar-rich conditions. The aim of this study was to explore the advantages of CLR as a gas-cleaning application, a process which offers continuous regeneration of the carbon deposits on catalysts. The tar-reforming performance of this Ni material and its influence on the gas composition and in particular its potential to increase the H2/CO ratio, were studied. The system was tested at reforming temperatures that ranged from 700°C to 880°C and at oxygen concentrations of 1.0% and 2.2% in the inlet feed to regenerator section. The results confirm the strong ability of the catalyst to reform tars. Higher process temperatures clearly promoted tar conversion, with 96% overall conversion at 880°C (99% if benzene is excluded), as compared with 45% conversion at 700°C. The hydrogen production was favored when temperature was raised. Though, a maximum ratio H2/CO of 2.2 was observed at 750°C. Finally, no time-on-stream deactivation of the catalyst in the CLR was observed during the test, which lasted almost 7 hours.
  •  
45.
  •  
46.
  • Cañete Vela, Isabel, 1992, et al. (författare)
  • Co-recycling of natural and synthetic carbon materials for a sustainable circular economy
  • 2022
  • Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 365
  • Tidskriftsartikel (refereegranskat)abstract
    • Circular economy approaches are commonly depicted by two cycles, where the biological cycle is associated with regeneration in the biosphere and the technical cycle with reuse, refurbishment, and recycling to maintain value and maximize material recovery. This work, instead, presents an alternative vision to the management of carbonbased materials that integrates the two cycles and enables the phasing-out of fossil carbon from the material system. The aim is to investigate the benefits and global potential of a co-recycling system, as an alternative to conventional recycling systems that separate biomass-based materials (e.g., wood, paper) from fossil-based materials (e.g., plastics). Thermochemical recycling technologies enable the conversion of carbon-based waste materials into high-quality synthetic products, promoting circularity and avoiding carbon losses such as carbon emissions and waste accumulation in landfills and nature. Here, the construction and analysis of co-recycling scenarios show how the deployment of thermochemical recycling technologies can decouple the material system from fossil resource extraction. Furthermore, energy use is reduced if pyrolysis and/or gasification are included in the portfolio of recycling technologies. In a decarbonized energy system, deployment of co-recycling can lead to near-zero carbon emissions, while in more carbon-intensive energy systems the choice of thermochemical recycling route is key to limiting carbon emissions.
  •  
47.
  • Cañete Vela, Isabel, 1992, et al. (författare)
  • Thermochemical recycling of tall oil pitch in a dual fluidized bed
  • 2023
  • Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 340
  • Tidskriftsartikel (refereegranskat)abstract
    • Crude tall oil is a by-product obtained from the manufacture of chemical wood pulp. The residue obtained after the distillation of this product is known as tall oil pitch (TOP). This complex fraction is a highly viscous liquid that consists mainly of free fatty acids, fatty acids derivatives, rosin acids and additives. Given its complex composition, it is commonly used as fuel for heat production. In this work, steam cracking is proposed as an alternative treatment for this residue. Steam cracking can convert TOP into a valuable product gas that can be used in different applications including the production of green chemicals, moving towards a carbon circular economy. The experimental tests were performed in the Chalmers pilot scale Dual Fluidized Bed, consisting of a steam cracker and a combustor. For these experiments, the thermochemical decomposition of 150–175 kg/h TOP was performed at the steam cracker at two different temperatures (775 and 825 °C) to evaluate the influence of this parameter on the obtained products. Wood pellets were also tested as reference material for the highest temperature. The distribution of the obtained products was analysed. Results show that TOP can be regarded as a by-product instead of a residue and used as feedstock for the recovery of chemical building blocks and syngas via thermochemical recycling. Between 40 and 50 % of the carbon present in the fuel is kept in the permanent gases, while about 20 % is in aromatic hydrocarbons. Compared to biomass, the aromatics yield obtained for TOP is much higher (190 g/kg for TOP and 13 g/kg for biomass). Among the species found, benzene, toluene and xylene, represent between 62 and 72 % of the total measured aromatics. Regarding the gas fraction, the production of valuable light hydrocarbons (such as ethylene and propylene) is more pronounced in the TOP residue than in the biomass. In addition, an energy balance over the system was estimated and showed that TOP thermochemical recycling can be self-sustained in a Dual Fluidized Bed if the non-valuable products are combusted. The results obtained in this work indicate that this TOP could be an appealing option to consider as a source of biorefinery revenue leading to the circular use of waste.
  •  
48.
  • Corcoran, Angelica, 1988, et al. (författare)
  • Ash Properties of Ilmenite Used as Bed Material for Combustion of Biomass in a Circulating Fluidized Bed Boiler
  • 2014
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 28:12, s. 7672-7679
  • Tidskriftsartikel (refereegranskat)abstract
    • Both agglomeration of bed material and corrosion of heat transfer equipment are issues related to combustion of biomass in a fluidized bed boiler. The biomass-ash component potassium is considered a major contributor for both phenomena. In this study, the conventionally used bed material, silica sand, was replaced with up to 40 wt % by the natural ore ilmenite in Chalmers 12 MWth circulating fluidized bed (CFB) boiler. In this study the purpose was to evaluate the physical and chemical changes ilmenite undergoes during this process. Close observations revealed that ilmenite underwent segregation of iron to the surfaces and an enrichment of titanium in the particle core. The ash formed a calcium-rich double layer on the particle, surrounding the iron layer. A diffusion of potassium into the particle core was also seen which led to the formation of KTi8O16. In addition to evaluating how ash components interact with the material, the ilmenite was leached and investigated as a possible potassium capturer. Leaching experiments on the used ilmenite showed that calcium and potassium were leachable to a very limited degree, namely, to less than 0.2 and 1 wt %, respectively, of the total content. The diffusion of potassium into the core of the particle could reduce both agglomeration and corrosion issues and could thereby be of great value for the improvement of the resistance of the bed material agglomeration in the fluidized bed boiler.
  •  
49.
  • Corcoran, Angelica, 1988, et al. (författare)
  • Comparing the structural development of sand and rock ilmenite during long-term exposure in a biomass fired 12 MWth CFB-boiler
  • 2018
  • Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 171, s. 39-44
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxygen Carrier Aided Combustion (OCAC) is a novel combustion concept with the purpose to increase the overall efficiency in conventional circulating fluidized bed (CFB) boilers. By replacing the commonly used bed material with an oxygen carrier (OC), the conceptual idea is to utilize the fluid dynamics in a CFB and the inherent oxygen transport supported by the OC to increase the oxygen distribution within the furnace in time and space. The OCAC concept has been successfully validated and further reached long-term demonstration in full scale operation (75-MW th ). This work presents a first evaluation of how ilmenite particles are affected in regard to mechanical resistance during long-term exposure to OCAC conditions in Chalmers 12-MW th CFB-boiler. A sand and a rock ilmenite are evaluated with regard to their mechanical stability. For evaluation, samples of the fresh materials and samples collected during operation in the Chalmers boiler are investigated. The study shows that the two materials differ in how the mechanical degradation occurs with exposure time. The sand ilmenite form cavities which are held together by an ash layer before they are shattered into numerous pieces, whereas the rock ilmenite develops distinct cracks that cause splitting of the particles.
  •  
50.
  • Corcoran, Angelica, 1988, et al. (författare)
  • Mechanism for Migration and Layer Growth of Biomass Ash on Ilmenite Used for Oxygen Carrier Aided Combustion
  • 2018
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 32:8, s. 8845-8856
  • Tidskriftsartikel (refereegranskat)abstract
    • Biomass is recognized as a CO2-neutral energy resource. However, biomass is a challenging fuel to combust because of its heterogeneity with regard to the content of inorganic constituents, volatiles, and moisture. Oxygen carrier aided combustion (OCAC) is a process advancement that provides enhanced combustion in existing circulating fluidized bed (CFB) units. The oxygen carrier has a central role in the OCAC concept through the oxygen transport it provides. The natural mineral ilmenite (FeTiO3) has been identified as a promising potential oxygen carrier. In order to ensure the feasibility even for long-term operation in industrial-scale processes, it is imperative to understand the evolution of the material during an OCAC process. In the present study, ilmenite was used as the bed material in the Chalmers 12 MWth CFB boiler during OCAC with woody biomass as fuel. Bed material samples were extracted from the bed inventory at different time intervals ranging from 5 to over 300 h. This paper proposes a mechanism for migration and layer growth of biomass ash on the ilmenite used as the oxygen carrier in a CFB combustor. It was found that with increased time of exposure, potassium migrated into the particle core. Longer process times led to the formation of a calcium layer around the particle, and simultaneously, migration of calcium inward on the particle was observed. Thermodynamic calculations were used along with analysis techniques in order to build a hypothesis for the possible mechanism of ash-bed material interaction.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-50 av 232
Typ av publikation
tidskriftsartikel (115)
konferensbidrag (88)
rapport (12)
bokkapitel (8)
samlingsverk (redaktörskap) (6)
bok (1)
visa fler...
doktorsavhandling (1)
licentiatavhandling (1)
visa färre...
Typ av innehåll
refereegranskat (160)
övrigt vetenskapligt/konstnärligt (71)
populärvet., debatt m.m. (1)
Författare/redaktör
Thunman, Henrik, 197 ... (232)
Seemann, Martin, 197 ... (67)
Leckner, Bo G, 1936 (56)
Berdugo Vilches, Ter ... (30)
Lind, Fredrik, 1978 (28)
Johnsson, Filip, 196 ... (22)
visa fler...
Larsson, Anton, 1984 (19)
Ström, Henrik, 1981 (18)
Maric, Jelena, 1983 (16)
Pallarès, David, 197 ... (14)
Johansson, Robert, 1 ... (14)
Berguerand, Nicolas, ... (14)
Hermansson, Sven, 19 ... (13)
Sasic, Srdjan, 1968 (10)
Alamia, Alberto, 198 ... (9)
Åmand, Lars-Erik, 19 ... (9)
Knutsson, Pavleta, 1 ... (9)
Ghirelli, Federico, ... (9)
Israelsson, Mikael, ... (8)
Harvey, Simon, 1965 (7)
Maggiolo, Dario, 198 ... (7)
Rönnbäck, Marie (7)
Cañete Vela, Isabel, ... (7)
González Arias, Judi ... (7)
Mandviwala, Chahat, ... (7)
Heyne, Stefan, 1979 (5)
Corcoran, Angelica, ... (5)
Cherednichenko, Serg ... (4)
Breitholtz, Claes, 1 ... (4)
Normann, Fredrik, 19 ... (4)
Davidsson, Kent (4)
Samuelsson, J (3)
Andersson, Klas, 197 ... (3)
Berndes, Göran, 1966 (3)
Tullin, Claes (3)
Santos, Olga (3)
Bidgoli, Hosein, 198 ... (3)
Forero Franco, Renes ... (3)
Gyllén, Angelica, 19 ... (3)
Samuelsson, Jessica (2)
Samuelsson, Peter (2)
Magnusson, Ingemar (2)
Davidsson, Kent, 196 ... (2)
Neves, D. (2)
Haro, Pedro (2)
Atongka Tchoffor, Pl ... (2)
Larsson, Anton (2)
Faust, Robin, 1992 (2)
Edvardsson, Elin, 19 ... (2)
Brink, Anders (2)
visa färre...
Lärosäte
Chalmers tekniska högskola (232)
RISE (8)
Kungliga Tekniska Högskolan (2)
Lunds universitet (1)
Högskolan i Borås (1)
Språk
Engelska (226)
Svenska (6)
Forskningsämne (UKÄ/SCB)
Teknik (229)
Naturvetenskap (22)
Lantbruksvetenskap (5)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy