| 1. |
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| 2. |
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| 3. |
- Gunarathne, Duleeka S., et al.
(författare)
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Performance of an effectively integrated biomass multi-stage gasification system and a steel industry heat treatment furnace
- 2016
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 170, s. 353-361
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Tidskriftsartikel (refereegranskat)abstract
- The challenges of replacing fossil fuel with renewable energy in steel industry furnaces include not only reducing CO2 emissions but also increasing the system energy efficiency. In this work, a multi-stage gasification system is chosen for the integration with a heat treatment furnace in the steel powder industry to recover different rank/temperature waste heat back to the biomass gasification system, resulting higher system energy efficiency.A system model based on Aspen Plus was developed for the proposed integrated system considering all steps, including biomass drying, pyrolysis, gasification and the combustion of syngas in the furnace. Both low temperature (up to 400 °C) and high temperature (up to 700 °C) heat recovery possibilities were analysed in terms of energy efficiency by optimizing the biomass pretreatment temperature.The required process conditions of the furnace can be achieved by using syngas. No major changes to the furnace, combustion technology or flue gas handling system are necessary for this fuel switching. Only a slight revamp of the burner system and a new waste heat recovery system from the flue gases are required.Both the furnace efficiency and gasifier system efficiency are improved by integration with the waste heat recovery. The heat recovery from the hot furnace flue gas for biomass drying and steam superheating is the most promising option from an energy efficiency point of view. This option recovers two thirds of the available waste heat, according to the pinch analysis performed. Generally, depending on the extent of flue gas heat recovery, the system can sustain up to 65% feedstock moisture content at the highest pyrolysis temperature studied.
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| 4. |
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| 5. |
- Hulme-Smith, Christopher, 1989-, et al.
(författare)
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Spreadability Testing of Powder for Additive Manufacturing
- 2020
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Ingår i: Berg- und Huttenmännische Monatshefte (BHM). - : Springer Nature. - 0005-8912 .- 1613-7531. ; 166:1, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- The spreading of powders into thin layers is a critical step in powder bed additive manufacturing, but there is no accepted technique to test it. There is not even a metric that can be used to describe spreading behaviour. A robust, image-based measurement procedure has been developed and can be implemented at modest cost and with minimal training. The analysis is automated to derive quantitative information about the characteristics of the spread layer. The technique has been demonstrated for three powders to quantify their spreading behaviour as a function of layer thickness and spreading speed.
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| 6. |
- Liu, Hao, et al.
(författare)
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A thermodynamic study of hot syngas impurities in steel reheating furnaces : Corrosion and interaction with oxide scales
- 2014
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 77, s. 352-361
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Tidskriftsartikel (refereegranskat)abstract
- Environmental concerns lead industries to implement gasified biomass (syngas) as a promising fuel in steel reheating furnaces. The impurities of syngas as well as a combination with iron oxide scale form complex mixtures with low melting points, and might cause corrosion on steel slabs. In this paper, the effects of syngas impurities are thermodynamically investigated, when scale formation on the steel slabs surface simultaneously takes place. A steel reheating furnace can be divided into preheating, heating, and soaking zones where the temperature of a steel slab changes respectively. Therefore, the thermodynamic calculation is performed at different temperatures to predict the fate of impurities. Then, the stable species are connected with respective zones in a reheating furnace. It is concluded that reactions due to alkali compounds, chloride, and particulate matter could take place on steel slabs. In the low temperature range, interaction of sodium chloride occured with pure iron prior to scale formation. Then, at high temperature the reactions of impurities are notable with iron oxides due to scale growing. Furthermore, the multicomponent reactions with syngas impurities showed that most of alkali contents evaporate at first stages, and only small amounts of them remain in slag at high temperature.
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| 7. |
- Marchetti, Lorenzo, et al.
(författare)
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On Metal Powder Tribocharging and Humidity Adsorption
- 2022
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Ingår i: World PM 2022 Congress Proceedings. - : European Powder Metallurgy Association (EPMA).
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Konferensbidrag (refereegranskat)abstract
- In this work, three characterization techniques were applied to a set of alloys in fine powder form (TiAl6V4, AlSi10Mg, AlSi7, 316L, ferritic stainless steel, martensitic stainless steel and WC-Co-mixes). We sought deeper understanding of response to humidity and flowability as a result of the powder alloy. Slight tribo-charging (induced and measured using a GranuCharge setup) against metal surfaces was found to occur for all alloys. Although the accumulated charge was small and dissipated quickly. Greater charging occurs if the environment is humid, and if the powder slides against plastic surfaces. Dynamic Vapor Sorption (DVS) was employed to understand the adsorption capacity of powders. It showed that WC-Co-mixes adsorbed much more humidity than the other materials. Some alloys retained some of the adsorbed mass when humidity returned to normal conditions. RPA was tested on powders during exposure to 20-98% RH, which above 80% RH caused declining flowability.
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| 8. |
- Mellin, Pelle, et al.
(författare)
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A proposed Swedish national standard and best practice for detection of Ar in PM hip material
- 2018
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Ingår i: Euro PM 2018 Congress and Exhibition. - : European Powder Metallurgy Association (EPMA). - 9781899072507
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Konferensbidrag (refereegranskat)abstract
- Ar in metal is present as gaseous voids which affect the material performance; most notably the mechanical properties. In agreement with literature findings, our investigation confirms this for 316L steel produced by PM HIP. Detecting the Ar is possible by microscopy, but more reliably with inert gas fusion followed by gas chromatography or mass spectrometry. The users of these techniques have accumulated experience over the years and consider them robust, especially in terms of distinguishing a presence or absence of Ar. Since consensus has emerged, a standard is now possible. We propose firstly a national standard. It may be used as a quality agreement between the purchaser and provider of the PM HIP service. The proposed standard considers the distinctiveness of PM HIP. For example that Ar tends to segregate in PM HIP cans. In fact, consensus has also been reached on how to reliably sample from PM HIP cans. © European Powder Metallurgy Association (EPMA).
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| 9. |
- Mellin, Pelle, 1985-, et al.
(författare)
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Accuracy and Potential Use of a Developed CFD-pyrolysis Model for Simulating Lab-scale Bio Oil Production
- 2012
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Ingår i: The 20th EU BC&E Online Proceedings 2012. - 9788889407547 ; , s. 953-959
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The paper describes development of a CFD¬pyrolysis model using an Eularian-Eularian framework with an implemented pyrolysis reaction model. The CFD¬pyrolysis model is used to simulate the bubbling fluidized bed reactor integrated in a new experimental fast pyrolysis process for bio oil production. The model is compared to experiments in aspect of outlet gas composition, temperature and bed height. Tar behavior and yield of bio oil are illustrated and a parametric study investigates impact of flow rate and temperature on bio oil yield. The results show a tolerable fit compared to measurements and reasonable tendencies in the parametric study.
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| 10. |
- Mellin, Pelle, et al.
(författare)
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An Euler–Euler approach to modeling biomass fast pyrolysis in fluidized-bed reactors – Focusing on the gas phase
- 2013
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; 58:1-2, s. 344-353
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Tidskriftsartikel (refereegranskat)abstract
- A developed 3D Euler–Euler CFD model, with an integrated pyrolysis model, is proposed as a way of predicting vapor phase dynamics and product distributions in the fluidized bed process for biomass fast pyrolysis. The main interest in this work is the gases resulting from the pyrolysis mixed with the fluidizing gas. We propose therefore a simple rendering of the solid material while directing attention to the vapor phase. At the same time the required computational resources for reaching stabilized conditions in the reactor are reduced. Temperature profile, velocity profile and pyrolysis products are predicted and globally verified by a series of parallel cases, which are compared to experimental measurements and known trends of liquid, solid and gas yields. The comparison of experimental measurements and model predictions satisfy the accuracy of the model and on a quantitative basis, the product yields agree with commonly known trends of bio oil versus temperature and residence time.
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| 11. |
- Mellin, Pelle, et al.
(författare)
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Biomass availability in Sweden for use in blast furnaces : International Conference on Applied Energy, ICAE2014
- 2014
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Ingår i: Energy Procedia. - : Elsevier. ; , s. 1352-1355
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Konferensbidrag (refereegranskat)abstract
- Based on the type of BF operated in Sweden, the pulverized coal (PC) has primarily been considered replaceable. If replacing the PC, a reduction of 1.25 Mton CO2 annually is possible, which would require approximately 4 TWh charcoal (0.46 Mton) or 7.14 TWh of dry raw biomass. This amount of biomass is substantial and availability is the main concern discussed in this paper. Uncertainty of the future biomass supply makes predictions beyond 2030 difficult. However, the predictions used in this work indicate that there is an unused potential, which could cover the need of all PCI in Sweden. Other aspects could potentially limit the proportion of PCI replaced by biomass, which should be further investigated.
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| 12. |
- Mellin, Pelle, et al.
(författare)
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Biomass availability in Sweden for use in blast furnaces
- 2014
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Ingår i: Energy Procedia. - : Elsevier Ltd. ; , s. 1352-1355
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Konferensbidrag (refereegranskat)abstract
- Based on the type of BF operated in Sweden, the pulverized coal (PC) has primarily been considered replaceable. If replacing the PC, a reduction of 1.25 Mton CO2 annually is possible, which would require approximately 4 TWh charcoal (0.46 Mton) or 7.14 TWh of dry raw biomass. This amount of biomass is substantial and availability is the main concern discussed in this paper. Uncertainty of the future biomass supply makes predictions beyond 2030 difficult. However, the predictions used in this work indicate that there is an unused potential, which could cover the need of all PCI in Sweden. Other aspects could potentially limit the proportion of PCI replaced by biomass, which should be further investigated.
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| 13. |
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| 14. |
- Mellin, Pelle, 1985-, et al.
(författare)
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CFD Modelling of Heat Supply in Fluidized Bed Fast Pyrolysis of Biomass
- 2014
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Ingår i: Proceedings of the 10th International Conference on Computational Fluid Dynamics in the Oil & Gas, Metallurgical and Process Industries (CFD 2014). - 9788214057416
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper investigates the heat supply to the fast pyrolysis process, by addition of oxygen in the fluidizing gas. Since the technology will be further developed, a solution for the heat supply in a large-scale reactor must be conceived, which is one option to achieve the primary target: to operate with as little extra heat as possible.Corrections for the granular bed material and the biomass particles are implemented in the simulation. User Defined Functions (UDF) is extensively used to describe interactions of heat and momentum between the phases and a chemistry model is employed to describe the chemical reactions after pyrolysis.The results are preliminary; however, the oxygen clearly reacts to provide heat. Primarily the secondary tar reacts and a loss of about 30% organic liquid yield is the result in this simulation, at an equivalence ratio of 0.026.If heat only can be recovered from the bed zone, through the bed material, then a higher equivalence ratio than what was investigated in this paper would be needed.If heat can be recovered from the whole reactor then a slight injection of oxygen would result in an autothermal system; which means the necessary heat to generate and pre-heat steam would be available.Temperature instability in the freeboard prevented investigation of higher equivalence ratios, which should be pursued in further work.
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| 15. |
- Mellin, Pelle, et al.
(författare)
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Comprehensive secondary pyrolysis in fluidized-bed fast pyrolysis of biomass, a fluid dynamics based modelling effort
- 2015
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Ingår i: 12TH INTERNATIONAL CONFERENCE ON COMBUSTION & ENERGY UTILISATION. - : Elsevier BV. ; , s. 281-284
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Konferensbidrag (refereegranskat)abstract
- Homogenous secondary pyrolysis is category of reactions following the primary pyrolysis and presumed important for fast pyrolysis. For the comprehensive chemistry and fluid dynamics, a probability density functional (PDF) approach is used; with a kinetic scheme comprising 134 species and 4169 reactions being implemented. With aid of acceleration techniques, most importantly Dimension Reduction, Chemistry Agglomeration and In-situ Tabulation (ISAT), a solution within reasonable time was obtained. More work is required; however, a solution for levoglucosan (C6H10O5) being fed through the inlet with fluidizing gas at 500 degrees C, has been obtained. 88.6 % of the levoglucosan remained non-decomposed, and 19 different decomposition product species were found above 0.01 % by weight. A homogenous secondary pyrolysis scheme proposed can thus be implemented in a CFD environment and acceleration techniques can speed-up the calculation for application in engineering settings.
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| 16. |
- Mellin, Pelle, 1985-, et al.
(författare)
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Computational fluid dynamics modeling of biomass fast pyrolysis in a fluidized bed reactor, using a comprehensive chemistry scheme
- 2014
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Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 117:Part A, s. 704-715
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Tidskriftsartikel (refereegranskat)abstract
- The CFD modeling for fast pyrolysis has previously focused on the major pyrolysis products; liquid, charand gas. This paper introduces a new approach to biomass pyrolysis; integrating a complex scheme of reactions including formation of such components as levoglucosan. The 3-D simulation takes into account the complex breakdown of each biomass subcomponent, the fluid dynamics of the process as well as the heat and momentum transfer of three Eulerian phases.The pyrolysis products include reference species that reflects the composition of the bio oil, gas fraction and char fraction. A number of reactions are in addition applied to account for the thermal cracking of tar compounds and the final compositions are compared to experimental yields. The results show that the predicted pyrolysis products reflect the experimental yields satisfactorily, apart from the water content which is under predicted. Most importantly though, the approach is computationally feasible and it should be useful for future work.
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| 17. |
- Mellin, Pelle, et al.
(författare)
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COPGLOW and XPS investigation of recycled metal powder for selective laser melting
- 2017
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Ingår i: Powder Metallurgy. - : Informa UK Limited. - 0032-5899 .- 1743-2901. ; 60:3, s. 223-231
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to compare, in terms of depth composition profile, a recycled hastelloy X powder and a virgin powder of the same alloy. We compare also the COPGLOW (compacted powder glow discharge analysis) method to the more established XPS (X-ray photoelectron spectroscopy) technique, in terms of similarity in reported elemental contents. A good match between the two methods was obtained on the surface of the powder particles (using an etching depth of 1 nm). Similar oxide layer thickness, of about 0.5–1 nm, was found on both powders by COPGLOW. Oxidation sensitive elements, such as Cr, were found on the surfaces by both XPS and COPGLOW on both powders. Surface content of Si appears to have decreased during use in selective laser melting. Finally, the two methods did not otherwise reveal any unexpected features in the depth profiles.
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| 18. |
- Mellin, Pelle, et al.
(författare)
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Detecting argon trapped in reference samples made by hot isostatic pressing
- 2016
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Ingår i: World PM 2016 Congress and Exhibition. - : European Powder Metallurgy Association (EPMA). - 9781899072484
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Konferensbidrag (refereegranskat)abstract
- We reveal in this paper a procedure to make reference materials containing a known level of Ar. Risk assessment when detecting Ar in a production material is based on the content relative to a specified safety limit (usually 50 ngAr/gsteel). Hence we only need to know if a production material contains more or less than this limit. Now, we can produce material at this limit. To evaluate, we use two types of instruments, on the following contents: 24, 48, 71, 95 and ngAr/gsteel. We found that all instruments could distinguish a higher and a lower level, from the safety limit. These contents are close to the lowest detectable limit for both instruments. The instruments are a G8 Galileo from Bruker Elemental and an ELTRA-Werf (several units) from Takon AB. The mechanisms of Argon segregation are reflected upon as the need for a uniform distribution in reference samples is important. Especially if one would do the instrument calibration solely based on reference samples in the future.
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| 19. |
- Mellin, Pelle, et al.
(författare)
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Evaluating flowability of additive manufacturing powders, using the gustavsson flow meter
- 2016
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Ingår i: World PM 2016 Congress and Exhibition. - : European Powder Metallurgy Association (EPMA). - 9781899072484
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Konferensbidrag (refereegranskat)abstract
- The Gustavsson flow meter (including standard ISO-13517) is in this paper used to measure flow rate of fine AM powders. In the current paper, the results are compared to the Hall flow meter and a Freeman FT4 powder rheometer in terms of success of measuring these AM powders. The robustness is clearly superior to the Hall flow meter. Compared to using the rheometer, the Gustavsson flow meter is faster and simpler to use; however, other powder-aspects are evaluated since little correlation was found. All methods of characterizing the flowability could distinguish between (1) two alloys, and (2) if the alloys were new or used (in SLM), and (3) if they were dried or non-dried.
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| 20. |
- Mellin, Pelle, et al.
(författare)
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Evaluating flowability of additive manufacturing powders, using the Gustavsson flow meter
- 2017
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Ingår i: Metal Powder Report. - : Elsevier Ltd. - 0026-0657 .- 1873-4065. ; 72:5, s. 322-326
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Tidskriftsartikel (refereegranskat)abstract
- The Gustavsson flow meter (including standard ISO-13517) is in this paper used to measure flow rate of fine AM powders. In the current paper, the results are compared to the Hall flow meter and a Freeman FT4 powder rheometer in terms of success of measuring these AM powders. The range of possible powders to measure is smaller with Gustavsson flow meter; but in this range, the difference in flow time is greater compared to the Hall flow meter. Compared to using the rheometer, the Gustavsson flow meter is faster and simpler to use; however, other powder-aspects are evaluated since little correlation was found. For the powders in this paper, all methods of characterizing the flowability could distinguish between (1) two alloys, and (2) if the alloys were new or used (in SLM), and (3) if they were dried or non-dried.
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| 21. |
- Mellin, Pelle, et al.
(författare)
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Incorporating gases (Ar, H2) in PM HIP canisters, using diffusion-filled microspheres
- 2018
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Ingår i: Euro PM 2018 Congress and Exhibition. - : European Powder Metallurgy Association (EPMA). - 9781899072507
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Konferensbidrag (refereegranskat)abstract
- Microspheres are hollow bubbles with a wide range of shell materials available on the market. Gases may enter microspheres via diffusion provided that the temperature is raised. In this paper we used polymeric microspheres to incorporate and control the level of Ar in reference material made by PM HIP, and glass (SiO2) microspheres to incorporate H2 for oxide reduction of PM HIP material. For the incorporation of Ar via polymeric microspheres, we failed to control all factors in the tests with Ar. In spite of that, we can utilize this method to create a homogenous reference material. For the incorporation of H2 via glass (SiO2) microspheres, higher filling pressure is permitted owing to the higher strength of this material. Up to 700 bar filling pressure has been achieved in work aiming for automotive applications. Once the microsphere, after filling, regain room temperature the H2 is locked inside and may be handled safely. We have used this idea to reduce internal and surface oxides on metal powders in the canisters before Hot Isostatic Pressing (HIP), with good results.
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| 22. |
- Mellin, Pelle, 1985-, et al.
(författare)
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Influence of Reaction Atmosphere (H2O, N2, H2, CO2, CO) on Fluidized-Bed Fast Pyrolysis of Biomass Using Detailed Tar Vapor Chemistry in Computational Fluid Dynamics
- 2015
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 54:33, s. 8344-8355
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Tidskriftsartikel (refereegranskat)abstract
- Secondary pyrolysis in fluidized bed fast pyrolysis of biomass is the focus of this work. A novel computational fluid dynamics (CFD) model coupled with a comprehensive chemistry scheme (134 species and 4169 reactions, in CHEMKIN format) has been developed to investigate this complex phenomenon. Previous results from a transient three-dimensional model of primary pyrolysis were used for the source terms of primary products in this model. A parametric study of reaction atmospheres (H2O, N2, H2, CO2, CO) has been performed. For the N2 and H2O atmosphere, results of the model compared favorably to experimentally obtained yields after the temperature was adjusted to a value higher than that used in experiments. One notable deviation versus experiments is pyrolytic water yield and yield of higher hydrocarbons. The model suggests a not overly strong impact of the reaction atmosphere. However, both chemical and physical effects were observed. Most notably, effects could be seen on the yield of various compounds, temperature profile throughout the reactor system, residence time, radical concentration, and turbulent intensity. At the investigated temperature (873 K), turbulent intensity appeared to have the strongest influence on liquid yield. With the aid of acceleration techniques, most importantly dimension reduction, chemistry agglomeration, and in-situ tabulation, a converged solution could be obtained within a reasonable time (∼30 h). As such, a new potentially useful method has been suggested for numerical analysis of fast pyrolysis.
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| 23. |
- Mellin, Pelle, et al.
(författare)
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Moisture content analysis of metal powders, using oven desorption followed by Karl Fischer titration
- 2018
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Ingår i: Euro PM 2018 Congress and Exhibition. - : European Powder Metallurgy Association (EPMA). - 9781899072507
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Konferensbidrag (refereegranskat)abstract
- In this paper, we use Oven Desorption followed by Karl Fischer Titration (KF), to measure moisture content in a newly opened PBF-LB Hasteloy X powder (we found 28.8 ppm), an PBF-EB powder (13.7 ppm) and a HIP powder (6.7 ppm). This method heats a powder sample inside a hermetically closed vial, in an oven. At the same time an inert gas flow enters, flushes out the evaporated water and exits the vial, via a double hollow needle. The gas-water mixture that exits is directed to the Karl Fischer Titration, where the evaporated moisture is quantified. Included is also a comparison with thermogravimetric analysis (TGA) and a climate chamber moisturization experiment of a PBF-LB HX powder followed by KF analysis. After the moisturization and KF analysis, the same powder was characterized in terms of oxygen content.
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| 24. |
- Mellin, Pelle, et al.
(författare)
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Moisture in Metal Powder and Its Implication for Processability in L-PBF and Elsewhere
- 2020
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Ingår i: Berg- und Huttenmännische Monatshefte (BHM). - 0005-8912 .- 1613-7531. ; 166:1, s. 33-39
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Tidskriftsartikel (refereegranskat)abstract
- The impact of moisture on flowability and spread- ability is discussed. More notably we also present research on the impact of moisture on built nickel-base material. One lot of a newly opened Hastelloy X (HX) L-PBF powder was split into two equal batches. One batch was moisturized using a programmable climate chamber, the other was un- treated. We built bars with both batches for mechanical testing, in an EOS M100, with a cold build plate. The mois- ture content of the two powder batches, before and after the build-jobs, were determined using Karl Fischer titration (KF). Regarding the periodical monitoring of moisture con- tent, it is not needed according to the findings of this paper. More moisture contributes to a slightly higher O-content in the built material, and in turn, a very slight reduction in im- pact toughness. If a newly purchased powder exhibits poor flowability or high oxygen content, the analysis using oven- desorption followed by KF is recommended. If the moisture content is high, a drying of the powder is recommended
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| 25. |
- Mellin, Pelle, 1985-, et al.
(författare)
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Nano-sized by-products from metal 3D printing, composite manufacturing and fabric production
- 2016
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Ingår i: Journal of Cleaner Production. - Sweden : Elsevier. - 0959-6526 .- 1879-1786. ; 139, s. 1224-1233
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Tidskriftsartikel (refereegranskat)abstract
- Recently, the health and environmental perspective of nano-materials has gained attention. Most previous work focused on Engineered Nanoparticles (ENP). This paper examines some recently introduced production routes in terms of generated nano-sized by-products. A discussion on the hazards of emitting such particles and fibers is included. Fine by-products were found in recycled metal powder after 3D printing by Selective Laser Melting (SLM). The process somehow generated small round metal particles (~1e2 mm) that are possibly carcinogenic and respirable, but not small enough to enter by skin-absorption. With preventive measures like closed handling and masks, any health related effects can be prevented. The composite manufacturing in particular generated ceramic and carbonaceous particles that are very small and respirable but do not appear to be intrinsically toxic. The smallest features in agglomerates were about 30 nm. Small particles and fibers that were not attached in agglomerates were found in a wide range of sizes, from 1 μm and upwards. Preventive measures like closed handling and masks are strongly recommended. In contrast, the more traditional production route of fabric production is investigated. Here, brushing residue and recycled wool from fabric production contained few nano-sized by-products.
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| 26. |
- Mellin, Pelle, 1985-, et al.
(författare)
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Processing of biomass to Hydrocarbons – using a new catalytic steam pyrolysis route
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Obtaining renewable transportation fuel has been identified as one of the main challenges for a sustainable society. Catalytic pyrolysis followed by hydrotreatment has been demonstrated as one possible route for producing transportation fuels. Using steam in this process could have a number of benefits as given by our research effort. For this paper, we will show that a catalyst together with steam prolongs the activity of the catalyst by preventing coking. This means that both steam and catalyst mutually benefits the deoxygenation. The presented mass and energy balance shows that up to 40% of the calorific value of biomass remains in the deoxygenated oil, on dry basis. This is in contrast to the mass yield, which for the same case was 25%; meaning that the oil is of significantly higher quality with a high content of hydrocarbons. In addition, CFD studies have shown steam is able to redistribute the heat flux and provide more uniform operating conditions compared to for example nitrogen. In conclusion, this route using steam shows promise for displacing fossil transportation fuels, by upgrading of the liquid in existing refineries or next-generation bio refineries. In additional support of this, we have published a number of papers describing conventional fast pyrolysis using steam, CFD modeling for further understanding and experimental work using a combination of steam and firstly a bimetallic catalyst (Ni, V) then a metal modified HZSM5 catalyst (Ni, V, Zeolite, Binder). This paper connects all these individual studies and provides further understanding of the role of steam and the role of steam in combination with a catalyst, in the fast pyrolysis process.
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| 27. |
- Mellin, Pelle, 1985-
(författare)
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Pyrolysis of biomass in fluidized-beds: in-situ formation of products and their applications for ironmaking
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The iron and steel industry emitted 8 % of all CO2 emissions in Sweden, 2011. Investigating alternative energy carriers is the purpose of this thesis. By pyrolyzing biomass, an energetic solid, gaseous and liquid (bio oil) fraction is obtained. If pyrolyzing biomass in a fluidized-bed reactor, the highest value may be added to the combined products. Additional understanding of pyrolysis in fluidized beds is pursued, using Computational Fluid Dynamics (CFD) and comprehensive kinetic schemes. The obtained solid product is investigated as a bio-injectant in blast furnaces for ironmaking.A new approach of separately modeling, the primary and secondary pyrolysis, is developed in this thesis. A biomass particle devolatilizes during pyrolysis. Primary pyrolysis is the solid decomposition which results in the volatiles that can leave the particle. Secondary pyrolysis is the decompositions of these volatiles, primarily in the gas phase.The primary pyrolysis (35 species, 15 reactions) mainly occurs in the bed-zone and as such, the model needs to take into account the complex physical interaction of biomass-particles with the fluidizing media (sand) and the fluidizing agent (gas). This is accomplished by representing the components by Eulerian phases and implementing interaction terms, as well as using a Stiff Chemistry Solver for the implemented reactions. The secondary pyrolysis (not considering heterogeneous reactions), mainly occurs outside the bed zone in one phase. The fluid flow is simpler but the chemistry is more complex, with a larger variety of molecules emerging. Carrying out the simulations time-effectively, for the secondary pyrolysis (134 species, 4169 reactions) is accomplished by using Dimension Reduction, Chemistry Agglomeration and In-situ Tabulation (ISAT); in a Probability Density Functional (PDF) framework.An analysis of the numerical results suggest that they can be matched adequately with experimental measurements, considering pressure profiles, temperature profiles and the overall yield of gas, solid and liquid products. Also, with some exceptions, the yield of major and minor gaseous species can be matched to some extent. Hence, the complex physics and chemistry of the integrated process can be considered fairly well-considered but improvements are possible. A parametric study of reaction atmospheres (or fluidizing agents), is pursued as means of understanding the process better. The models revealed significant effects of the atmosphere, both physically (during the primary and secondary pyrolysis) and chemically (during secondary pyrolysis).During primary pyrolysis, the physical influence of reaction atmospheres (N2, H2O) is investigated. When comparing steam to nitrogen, heat flux to the biomass particles, using steam, is better distributed on a bed level and on a particle level.During secondary pyrolysis, results suggest that turbulence interaction plays an important role in accelerating unwanted decomposition of the liquid-forming volatiles. Steam, which is one of the investigated atmospheres (N2, H2O, H2, CO, CO2), resulted in a lower extent of unwanted secondary pyrolysis. Altough, steam neither resulted in the shortest vapor residence time, nor the lowest peak temperature, nor the lowest peak radical concentration; all factors known to disfavor secondary pyrolysis. A repeated case, using a high degree of turbulence at the inlet, resulted in extensive decompositions. The attractiveness of the approach is apparent but more testing and development is required; also with regards to the kinetic schemes, which have been called for by several other researchers.The solid fraction after pyrolysis is known as charcoal. Regarding its use in blast furnaces; modelling results indicate that full substitution of fossil coal is possible. Substantial reductions in CO2 emissions are hence possible. Energy savings are furthermore possible due to the higher oxygen content of charcoal (and bio-injectants in general), which leads to larger volumes of blast furnace gas containing more latent energy (and less non-recoverable sensible energy). Energy savings are possible, even considering additional electricity consumption for oxygen enrichment and a higher injection-rate on energy basis.A survey of biomass availability and existing technology suppliers in Sweden, suggest that all injection into Blast furnace M3 in Luleå, can be covered by biomass. Based on statistics from 2008, replacement of coal-by-charcoal from pyrolysis could reduce the on-site carbon dioxide emissions by 28.1 % (or 17.3 % of the emissions from the whole industry). For reference, torrefied material and raw biomass can reduce the on-site emissions by 6.4 % and 5.7 % respectively.
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| 28. |
- Mellin, Pelle, et al.
(författare)
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Simulation of Bed Dynamics and Primary Products from Fast Pyrolysis of Biomass : Steam Compared to Nitrogen as a Fluidizing Agent
- 2014
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:30, s. 12129-12142
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Tidskriftsartikel (refereegranskat)abstract
- Fast pyrolysis of biomass, using steam as a fluidizing agent, provides several benefits. In this paper, an unsteady multiphase computational fluid dynamics (CFD) model coupled with a comprehensive kinetic scheme for primary pyrolysis is used to obtain the formation rates of primary products and compare the profiles when operating with steam and nitrogen. The model only considers the physical effects of the fluidizing gas at the moment, although a literature review indicates the existence of various chemical and surface-interacting effects. At stabilized pyrolysis reaction rates, the product yields were compared to data found in the literature, which indicated similar yields; this supports the correct implementation of the kinetic model. However, the difference in overall rate and composition is very small when steam is compared to nitrogen. The simultaneous simulation of bed dynamics indicate a shifted formation rate of primary products toward the lower part of the fluidized bed, with an increase in solid vapor contact time and better temperature distribution as a result. More specifically, total heat flux to the biomass increased by 1396 in the lowest part of the reactor. In addition, more heat from the sand is carried through the gas phase when using steam: an increase by 9% in the overall reactor (25% in the lowest part), as indicated by the results. Finally, since no substantial differences in overall product formation rate and composition were found, the considerable effect of steam found in experiments and the literature is mainly (not exclusively) attributed to the chemical and surface-interacting mechanisms. Because of the complex nature of secondary pyrolysis in this process, a comprehensive gas-phase kinetic model is needed to investigate the effects of steam further. Coupling of both is difficult, because of computational constraints, as the present model already is very demanding. The obtained profiles of formation rate of primary products can however be used as an input to another model specifically made for studying homogeneous secondary pyrolysis reactions.
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| 29. |
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| 30. |
- Nilsson Åhman, Hanna, et al.
(författare)
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An Enhanced Understanding of the Powder Bed Fusion-Laser Beam Processing of Mg-Y-3.9wt%-Nd-3wt%-Zr-0.5wt% (WE43) Alloy through Thermodynamic Modeling and Experimental Characterization
- 2022
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- Powder Bed Fusion-Laser Beam (PBF-LB) processing of magnesium (Mg) alloys is gaining increasing attention due to the possibility of producing complex biodegradable implants for improved healing of large bone defects. However, the understanding of the correlation between the PBF-LB process parameters and the microstructure formed in Mg alloys remains limited. Thus, the purpose of this study was to enhance the understanding of the effect of the PBF-LB process parameters on the microstructure of Mg alloys by investigating the applicability of computational thermodynamic modelling and verifying the results experimentally. Thus, PBF-LB process parameters were optimized for a Mg WE43 alloy (Mg-Y-3.(9wt%)-Nd-3wt%-Zr-0.5wt%) on a commercially available machine. Two sets of process parameters successfully produced sample densities >99.4%. Thermodynamic computations based on the Calphad method were employed to predict the phases present in the processed material. Phases experimentally established for both processing parameters included alpha-Mg, Y2O3, Mg3Nd, Mg24Y5 and hcp-Zr. Phases alpha-Mg, Mg24Y5 and hcp-Zr were also predicted by the calculations. In conclusion, the extent of the applicability of thermodynamic modeling was shown, and the understanding of the correlation between the PBF-LB process parameters and the formed microstructure was enhanced, thus increasing the viability of the PBF-LB process for Mg alloys.
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| 31. |
- Nilsson Åhman, Hanna, et al.
(författare)
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Higher Laser power improves strength but reduces corrosion resistance of Mg WE43 processed by powder bed fusion
- 2024
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Ingår i: Materials Today Communications. - : Elsevier. - 2352-4928. ; 39
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Tidskriftsartikel (refereegranskat)abstract
- Powder bed fusion – laser beam (PBF-LB) of Mg alloys provides new possibilities for the production of complex structures with optimized designs, both for weight reduction in aerospace applications, as well as for patient-specific implants in orthopedic applications. However, even though numerous studies have been carried out on the topic, the influence of the individual PBF-LB process parameters on the microstructure and resulting material properties of Mg alloys remains ambiguous. Thus, this study aims to investigate the influence of laser power on the surface roughness, microstructure and resulting key material properties, namely corrosion resistance and mechanical performance. Samples were produced by PBF-LB from gas atomized Mg-4%Y-3%Nd-0.5%Zr (WE43) alloy powder, using three different laser powers: 60 W, 80 W, and 90 W. Contrary to expectation, the 90 W samples exhibited the highest degradation rate, while 60 W samples had the lowest, despite the latter having highest surface roughness and large internal pores. The higher degradation rate for the 90 W samples was instead found to stem from the near-surface microstructure. The higher energy input and subsequently reduced grain size, resulted in an increased amount of second phase precipitates than for the 60 W samples, thereby increasing the tendency for pitting via microgalvanic corrosion. For the tensile strength and elongation at break, the opposite trend was observed. Here, a reduction in grain size and an increase in precipitates for the 90 W samples were found to be beneficial. In conclusion, a definite influence of laser power on the formation of microstructure was observed, ultimately impacting the resulting corrosion and tensile properties of WE43. Future work should investigate the influence of other PBF-LB process parameters, with the aim of establishing an optimum balance between corrosion resistance and mechanical properties.
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| 32. |
- Nilsson Åhman, Hanna, et al.
(författare)
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Influence of Hot Isostatic Pressing on the corrosion resistance of Mg-4wt%Y-3wt%Nd processed by Laser - Powder Bed Fusion
- 2021
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Magnesium alloys have recently gained increased attention as a biodegradable metal implant. They can be biocompatible and have superior mechanical properties compared to the biodegradable polymeric implants used today. However, poor formability and excessive corrosion rates have limited the clinical implementation of Mg alloys to an extruded Mg-Y-Nd alloy .Additive manufacturing through Laser - Powder Bed Fusion (L-PBF) allows for the production of patient specific implant designs. Hot Isostatic Pressing (HIP) is a common method applied after printing to obtain fully dense materials for improved mechanical and corrosion properties. However, the amount of work done on L-PBF of Mg alloys remains limited. Esmaily et al found an improved corrosion resistance after HIP of a Mg-Y-Nd alloy processed by L-PBF, as evidenced by surface activity and H2 evolution over 24h. However, the influence of HIP on the long term corrosion properties and the part morphology after corrosion have not been evaluated. Herein we show that HIP can be highly detrimental to the long-term corrosion properties of a Mg alloy processed by L-PBF.
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| 33. |
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| 34. |
- Nilsson Åhman, Hanna, et al.
(författare)
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Microstructural Origins of the Corrosion Resistance of a Mg-Y-Nd-Zr Alloy Processed by Powder Bed Fusion - Laser Beam
- 2022
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Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media S.A.. - 2296-4185. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Magnesium alloys are biocompatible, biodegradable and have the ability to promote bone ingrowth, making them ideal candidate materials for replacing auto- and allografts in future treatments of large bone defects. Powder bed fusion-laser beam (PBF-LB) additive manufacturing of these alloys would further allow for the production of complex structures, optimized for bone grafting. However, the corrosion rates of structures processed by PBF-LB remain too high. An improved understanding of the influence of the microstructure generated during PBF-LB on the corrosion properties is considered key to their future implementation in implants. In this study, the effect of PBF-LB processing and subsequent hot isostatic pressing (HIP) on the microstructure and texture in different sample directions was studied and related to the corrosion behavior of a Mg-Y-Nd-Zr alloy. The results were compared with an extruded Mg-Y-Nd-Zr alloy. A higher amount of secondary phases resulted in a higher rate of localized corrosion for the PBF-LB processed material compared to that for the extruded one. Due to growth of the secondary phases, the corrosion rate was further increased after HIP. Moreover, a strong texture was observed in the PBF-LB material, and it was also enhanced in the HIP material. While this affected the electrochemical activity as measured by potentiodynamic polarization tests, any texture effect appeared to be masked by the contribution of the secondary phases in the longer-term mass change and hydrogen evolution tests. Future work should look further into the influence of individual process parameters on the microstructure and the resulting corrosion behavior of the material, to further clarify its interdependence.
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| 35. |
- Nilsson Åhman, Hanna
(författare)
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Powder Bed Fusion – Laser Beam of Mg alloy WE43 : Establishing the process – structure – properties relationship
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Powder bed fusion - laser beam (PBF-LB) of Mg alloy WE43 (Mg-4wt%Y-3wt%RE-Zr) has great potential for the development of future biodegradable metal implants, as well as aerospace lightweight materials. However, the work published thus far has mainly focused on obtaining a fully dense material, and the understanding of the relationship among the PBF-LB process parameters, structure and the resulting material properties remains limited. Thus, the aim of the thesis was to relate the main PBF-LB processing parameters to the formation of key microstructural features in WE43, and their effect on corrosion and tensile test properties. The work was carried out on PBF-LB processing units EOS M100 and EOS M290, and the investigated process parameters included laser power, laser scanning speed, hatch distance and sample wall thickness. Depending on the resulting thermal conditions, two main microstructural regions were observed. For process parameters resulting in warmer processes, such as higher laser powers and shorter scan lengths, mainly equiaxed dendritic grains were observed. The grains measured up to 10 µm in maximum diameter and exhibited a weak texture, with the inter-dendritic regions rich in Mg-RE intermetallic compunds. For process parameters resulting in conductive mode melting, mainly a lamellar structure was observed. The lamellar structure consisted in large grains with basal texture, and an intragranular structure where lines of Mg-RE intermetallic compunds precipitated parallel to the melt pool boundary. The larger grains had a maximum diameter of around 60 µm to 100 µm in the build direction, and up to 250 µm in the transverse direction, with a preferential growth along the melt pool.A larger number of dendritic grains was detrimental to the corrosion properties but resulted in higher tensile strength. The result was ascribed to the higher amount of Mg-RE intermetallics and the smaller grains, strengthening the material, but also causing microgalvanic corrosion. Hot isostatic pressing also resulted in growth of the secondary phases and was thus also detrimental to corrosion properties. While a change in hatch distance (40-60 mm) did not cause any dendritic structure to form, a higher hatch distance resulted in improved corrosion properties, but had minor effect on tensile properties, showing the possibilities of applying hatch distance variations to balance corrosion and tensile properties.In conclusion, the findings presented here show the possibilities of controlling the microstructure and thus the material properties by changing some of the key PBF-LB process parameters, and the major importance of understanding the relationship among process, structure and material properties of PBF-LB processed WE43.
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| 36. |
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| 37. |
- Niska, John, et al.
(författare)
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Investigating Potential Problems and Solutions of Renewable Fuel Use in Steel Reheating Furnaces
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Implementing renewable fuels in steel reheating furnaces can reduce carbon dioxide emissions from fossil fuels, so the steel industry is interested in finding the optimal method of implementation. The relatively low cost of solid biofuels from forest products make them an attractive candidate, but there is a risk of reaction between pellets ash and furnace brick. Therefore a test was conducted with wood pellets ash on a furnace brick to test the sensitivity to pellets ash. One problem is the formation of a glassy phase due to the interaction of furnace refractories with pellets ash. The risk for the formation of a glassy phase depends on the composition of the refractory, composition of the ash and the furnace conditions, for example, a glassy phase was found to form on a chamotte refractory furnace brick when a pellets ash and the brick were heated to 1200°C.One method to analyze the risk for volatile and low melting point compounds from solid biofuels is to use a tertiary phase diagram to divide various components in the ash. Oxides and compounds rich in the alkali metals (Na and K) tend to form volatile compounds. These alkali metal oxides together with silica can give low melting point phases for compositions near the bottom of this diagram. Ash compositions near the top of the diagram which are rich in CaO and MgO tend to have higher melting points. The wood pellets ash investigated was analysed and found to contain a large percentage of Ca, Si and Mg, expressed as CaO (44.4%), SiO2 (14.6%) and MgO (10.1%) and relatively modest amounts of the alkali metals Na and K expressed as Na2O (3.5%) and K2O (6.2%). This mostly stem wood pellets ash could give concern with the formation of a glassy phase, so biofuels with more twigs, leaves and bark with a higher concentration of alkali metals could give even greater concerns. Therefore alternatives like gasification should be considered.Gasification of solid biofuels is one way to avoid ash-forming compounds in reheating furnaces. A survey was performed to evaluate different gasification technologies, as well as existing applications of syngas in other high-temperature industries.
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| 38. |
- Saffari Pour, Mohsen, 1987-, et al.
(författare)
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Numerical Investigation of Syngas Combustion in a HiTAG System Using CFD Techniques
- 2014
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Ingår i: PROCEEDINGS of the 10th International Conference on Computational Fluid Dynamics in the Oil & Gas, Metallurgical and Process Industries. - Trondheim. - 9788214057416
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Konferensbidrag (refereegranskat)abstract
- Utilization of gasified biomass in the case of combustion could introduce a prominent way to high energy efficiency, pollutant emissions reduction, and heat recovery purposes. In this paper, secondary syngas combustion chamber of high temperature agent gasification (HiTAG) system is modelled with computational fluid dynamics (CFD) techniques. The numerical data in terms of temperature distribution and flue gas concentrations are compared with experimental measurements through the whole volume of such chamber. In order to reduce the pollutant emissions, and more efficient volumetric combustion, a low NOX burner is used in the secondary chamber. The validation of numerical results with experimental measurements shows a good consistency through the entire chamber. It is concluded that the NOX emission due to secondary air injection, and low NOX burner decreased significantly prior to spread in atmosphere. Moreover, the concentration of oxygen and carbon monoxide at the combustion exhaust reveals a reliable combustion system.
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| 39. |
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| 40. |
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| 41. |
- Sundqvist, Maria, et al.
(författare)
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System analysis of integrating fast pyrolysis to an iron and steel plant
- 2015
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Ingår i: ECOS 2015 - 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. - : International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. - 9782955553909
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Konferensbidrag (refereegranskat)abstract
- The reducing of CO2 allowance promotes steel industry to mitigate CO2 emissions. Utilization of biomass e.g., as injectants in the blast furnace to replace pulverized coal (PC), has been proposed as one promising option to meet these requirements in the short- Term. The aim of this work is to integrate a biomass fast pyrolysis to the iron and steel industry and to investigate the potential effects on the energy consumption and CO2 emission. In this work, an iron and steel plant from Sweden was chosen as a case study. An optimization model was extended to cover the fast pyrolysis units in the system boundary. The fast pyrolysis plant produces different types of biomass products i.e., bio-char, bio-oil and bio-syngas. Different alternative to utilize biomass products within the system were included in the model. The investigation shows that the integration of a fast pyrolysis units has great potential on, not only reducing CO2 emission, the potential energy savings.
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| 42. |
- Wang, Chuan, et al.
(författare)
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Biomass as blast furnace injectant : Considering availability, pretreatment and deployment in the Swedish steel industry
- 2015
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Ingår i: Energy Conversion and Management. - : Elsevier. - 0196-8904 .- 1879-2227. ; 102:SI, s. 217-226
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated and modeled the injection of biomass into blast furnaces (BF), in place of pulverized coal (PC) from fossil sources. This is the easiest way to reduce CO2 emissions, beyond efficiency improvements. The considered biomass is either pelletized, torrefied or pyrolyzed. It gives us three cases where we have calculated the maximum replacement ratio for each. It was found that charcoal from pyrolysis can fully replace PC, while torrefied material and pelletized wood can replace 22.8% and 20.0% respectively, by weight. Our energy and mass balance model (MASMOD), with metallurgical sub-models for each zone, further indicates that (1) more Blast Furnace Gas (BFG) will be generated resulting in reduced fuel consumption in an integrated plant, (2) lower need of limestone can be expected, (3) lower amount of generated slag as well, and (4) reduced fuel consumption for heating the hot blast is anticipated. Overall, substantial energy savings are possible, which is one of the main findings in this paper. Due to the high usage of PC in Sweden, large amounts of biomass is required if full substitution by charcoal is pursued (6.19 TWh/y). But according to our study, it is likely available in the long term for the blast furnace designated M3 (located in Luleå). Finally, over a year with almost fully used production capacity (2008 used as reference), a 28.1% reduction in on-site emissions is possible by using charcoal. Torrefied material and wood pellets can reduce the emissions by 6.4% and 5.7% respectively. The complete replacement of PC in BF M3 can reduce 17.3% of the total emissions from the Swedish steel industry.
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| 43. |
- Wang, C., et al.
(författare)
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Injecting different types of biomass products to the blast furnace and their impacts on the CO2 emission reduction
- 2015
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Ingår i: AISTech - Iron and Steel Technology Conference Proceedings. - : Association for Iron and Steel Technology, AISTECH. - 9781935117476 ; , s. 1525-1535
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Konferensbidrag (refereegranskat)abstract
- Recent years more research has been focusing on utilizing biomass in the blast furnaces (BFs). One driving force is linked to the climate change mitigation, i.e. to reduce CO2 emission from fossil reducing agents or fuels, by using biomass. The amounts of biomass that could be utilized in BF is limited by different parameters, such as metallurgical properties of reducing agents, fuel properties such as volatile content, fixed carbon and oxygen content, ash chemistry (S, Na2O, K2O, etc.). In this paper, different types of biomass products in the form of solid, liquid and gas are investigated as injectants to the blast furnace. The modelling work has been done for a BF from a Nordic country. The possible amounts of injected biomass products are presented. With the replacement ratios of pulverized coal (PC), the potential CO2emission reduction when injecting different biomass products is quantified. In addition, the strategy of using biomass at the studied iron-making plant is discussed. AISTech 2015 Proceedings
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| 44. |
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| 45. |
- Wang, C., et al.
(författare)
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Injection of solid biomass products into the blast furnace and its potential effects on an integrated steel plant
- 2014
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; , s. 2184-2187
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Konferensbidrag (refereegranskat)abstract
- This study is to investigate different types of biomass products' injection into the blast furnace (BF) to replace pulverized coal injection (PCI). The biomass products covered in the study are charcoal, torrefied material and wood pellets on the basis of Swedish forests. The modelling work has been performed in a specialized BF model. The modelling results show that charcoal has the significant effects on the BF operation. PCI can be replaced fully by charcoal, and only limited amount of torrefied material and wood pellets can be injected into BF. For the studied BF, the annual CO2 emission reduction potential from the replaced amount of PCI when injecting charcoal, torrefied material and wood pellets are about 1140 kton, 260 kton and 230 kton, respectively. In addition, a possible energy saving can be achieved for charcoal injection. A slightly higher P content in the hot metal may occur when injecting torrefied material.
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| 46. |
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