| 1. |
- 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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| 2. |
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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 10. |
- 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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