| 1. |
- Fröling, Morgan, 1966-, et al.
(författare)
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Bio-CCS - a model based case study from the mid Sweden region
- 2015
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Ingår i: Proceedings of Global Cleaner Production and Sustainable Consumption, Sitges Barcelona, November 1-4, 2015.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In its 2014 report, IPCC recommend Carbon Capture and Storage not only for fossil power plants but also for bioenergy to beable to meet the 2 degree target. In a case study, models for CCS applied to a combined heat and power (CHP) plant inÖstersund, Sweden, using wood chips as main fuel was assessed. The goal was to gain knowledge to be prepared to takemore rapid action if policy instruments are implemented in future. More "traditional" technology with absorption inmonoethanolamine (MEA) and subsequent underground storage uses a significant part of produced electricity, and in anenergy system perspective it is not necessarily the most efficient use of a limited wood resource. For processes withcomparatively low net climate impact, like bio-CHP, alternatives significantly more energy efficient per unit of capturedcarbon dioxide but only able to capture part of the total emitted carbon can be considered. One such alternative is to capturecarbon dioxide using microalgae. Key issues for assessment of processes in this case are how to store the carbon captured inthe algae biomass (e.g. in products) and for how long the carbon will be withdrawn from atmosphere with such storage.
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| 2. |
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| 3. |
- Forsberg, Fredrik, et al.
(författare)
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X-ray microtomography for sequential imaging and analysis of iron ore pellets under reduction
- 2012
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Ingår i: Scanmet IV. - Luleå : MEFOS. - 9789163708596 ; , s. 217-227
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Konferensbidrag (refereegranskat)abstract
- This work has been a part of the development of a method where x-ray microtomography and image analysis are used to quantify the crack distribution and propagation in iron ore pellets during reduction.Reduction experiments on 7 pellets, were performed in 4 steps during the transformation from hematite to magnetite at 500 °C. The pellet microstructure is imaged and visualized at each step using x-ray microtomography and the crack distribution characterized with image analysis.For the chosen pellet composition, networks of cracks are already visible in the unreduced state and show a successive growth during the first 30 minutes of reduction. As the transformation to magnetite is complete, crack growth has stopped and in several cases a partial regression is observed.It can be concluded that the use of X-ray microtomography has the potential to become an important tool for material characterization in iron ore pellet research due to its ability to gather information from the bulk of the material at several different stages of a process.
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| 4. |
- Hjortsberg, Erik
(författare)
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Attempts to use computerised tomography and image analysis to investigate the influence of the filling operation on the density of compressed rings
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Computerised tomography has the potential to become an invaluable tool for R&D activities within the field of powder metallurgy. At the present the method is however not sufficiently adapted for this application. Here a novel experimental routine combining computerised tomography with image analysis have been used to investigate the influence of the filling operation on the density distributions within compressed rings. Sufficient time was however not available to fully interpret the produced result and to validate the reliability of this technique. Analysis of less complex samples with known density distributions is suggested as a way to continue this investigation and to test the reliability of the method. The outline for a project where such a study could be perfom1ed is included in this report.
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| 5. |
- Hjortsberg, Erik, 1968-
(författare)
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Density Variations in Iron Powder Caused by Die Filling
- 2000
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Ingår i: PM2000.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this work the influence of the filling shoe movement on the powder density in a lilled. ring shaped cavity has been investigated. The outer diameter of the cavity was 29 cm and the approximate weight of powder in a filled cavity was 650g. The density variations between different parts of the ring and different types of filling operations have been measured. It has been determined that the movement of the filling shoe causes density variations in the filled powder and that these density variations are identical for rings filled under the same conditions. Conventional filling. where the filling shoe only performs one filling cycle resulted in density variations from 0.354 to 0.363 in relative density. By measuring the particle size distribution in different sections of the rings by laser interferometry it was also possible to detem1ine that the filling shoe movement has a segregating effect on the filled powder. By comparing the amount of segregation with other investigations it was possible to determine that this segregation only has a limited influence (less then 10 %) on the powder density and that the major part of the densification originated from the physical rearrangement of the powder particles.
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| 6. |
- Hjortsberg, Erik, 1968
(författare)
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Experimental approaches to powder filling and lubrication in powder die pressing
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is a continuous need to improve the mechanical properties of steel parts produced through powder metallurgy in order to ensure the market growth of this sector and competitiveness against alternative production techniques. One of the more promising routes able to achieve this is to aim for components with higher densities. Two potential areas for such improvements are deepened understanding of the powder filling process and lubricant behaviour during uniaxial pressing. These steps have received limited attention due to their complexity thus more easily achievable developments with larger impact on final properties, such as optimisation of alloy content, compaction pressure and sintering conditions, have so far always been present. During the time such aspects have been optimised, the need for more systematic investigations of filling and lubricant behaviour, has become increasingly apparent. There is a lack of experimental equipment able to study these problems and potential analysis techniques have not been adapted for the application. The aim of this project has been to develop and verify new techniques to make experimental data available, and use them to acquire new knowledge. An experimental device has been constructed which has been able to identify several factors within the filling process as responsible for density variations observed in the filled powder. A microscopic approach has been adopted in order to study the function and behaviour of lubricant during powder compaction. X-ray photoelectron spectroscopy, interference microscopy and scanning electron microscopy have been used to study the topography and lubricant distribution both at the surface of the compacted powder parts and at the surface of the compaction tools. From the results it has been possible to draw several new conclusions about lubricant behaviour during compaction and the results have indicated which variables that have to be considered in future investigations of lubricant behaviour and which microscopic factors that currently is limiting the compactability of powders containing a homogenously distributed lubricant.
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| 7. |
- Hjortsberg, Erik, 1968-, et al.
(författare)
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Filling induced density variations in metal powder
- 2002
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Ingår i: Powder Metallurgy. - : Informa UK Limited. - 0032-5899 .- 1743-2901. ; 45:2, s. 146-153
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Tidskriftsartikel (refereegranskat)abstract
- Filling induced density variations is a problem that has long been overlooked by powder metallurgy scientists. In this paper,densityvariations are addressed, both why they occur and what problems they may cause. A test method, including a test rig, is presented that is able to link several different factors to resulting powder densities. The relations are analysed and several density affecting mechanisms are suggested. These mechanisms could be used either to minimise density differences within parts or to control density by directing powder to critical areas.
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| 8. |
- Hjortsberg, Erik, et al.
(författare)
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Filling induced density variations in metal powder
- 2002
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Ingår i: Powder Metallurgy. - : Informa UK Limited. - 0032-5899 .- 1743-2901. ; 45:2, s. 146-153
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Tidskriftsartikel (refereegranskat)abstract
- Filling induced density variations is a problem that has long been overlooked by powder metallurgy scientists. In this paper,densityvariations are addressed, both why they occur and what problems they may cause. A test method, including a test rig, is presented that is able to link several different factors to resulting powder densities. The relations are analysed and several density affecting mechanisms are suggested. These mechanisms could be used either to minimise density differences within parts or to control density by directing powder to critical areas.
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| 9. |
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| 10. |
- Hjortsberg, Erik, 1968-
(författare)
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Studies of density variations in iron powder caused by the filling operation
- 2001
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Detailed information about the density within a part produced by compression of a granular material is perhaps the most important piece of information you need if you are to predict its properties. Nearly all mechanical properties are strongly dependent on the density and the density of a very small region within the part can potentially be disastrous if it has a density level considerably lower then the rest of the part. Filling induced density variations is a problem that long has been overlooked by powder metallurgy scientists. One of the factors that are making investigations difficult is the lack of methods to make experimental data available. In this work four different methods for this purpose have been evaluated.Metallographic examinationsHas proven to be a reliable method to provide information about the density variations in cut, 2 dimensional cross sections of PM samples. To produce the amount of data necessary to study the filling operation is however considered too labour intensive.Bulk densitv measurements of compressed samplesA simple and reliable method, perfect for thorough investigations of densityvariations in industrially produced PM components.Density measurements of filled powderAlthough not as accurate as bulk density measurements the increased flexibility of this method can be an advantage when investigating filling behaviour. A novel test rig was constructed that was able to identify and link several different factors to the resulting density variations.Computerised TomographyThis method has the potential to deliver the same information as metallographic examinations in a much faster and more reliable way. It has however not yet been established if the accuracy ofthe method is sufficient to provide information about the density variation in PM samples caused by the filling operation.With the bulk density and the filled powder methods deeper studies were also performed to increase the knowledge of powder filling behaviour. It has been established that the filling operation causes density variations within PM parts and that these variations are highly systematic. With the construction of the test rig it was possible to determine several aspects of the feed shoe cycle as responsible for these variations.
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