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  • 401.
    Grimm, Alejandro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Skoglund, Nils
    Umeå university.
    Boström, Dan
    Umeå university.
    Öhman, Marcus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bed agglomeration characteristics in fluidized quartz bed combustion of phosphorus-rich biomass fuels2011Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, nr 3, s. 937-947Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The bed agglomeration characteristics during combustion of phosphorus-rich biomass fuels and fuel mixtures were determined in a fluidized (quartz) bed reactor (5 kW). The fuels studied (separately and in mixtures) included logging residues, bark, willow, wheat straw, and phosphorus-rich fuels, like rapeseed meal (RM) and wheat distillers dried grain with solubles (DDGS). Phosphoric acid was used as a fuel additive. Bed material samples and agglomerates were studied by means of scanning electron microscopy (SEM) in combination with energy-dispersive X-ray spectroscopy (EDX), in order to analyze the morphological and compositional changes of coating/reaction layers and necks between agglomerated bed particles. Furthermore, bed ash particles were separated by sieving from the bed material samples and analyzed with SEM/EDS and powder X-ray diffraction (XRD). For logging residues, bark, and willow, with fuel ash rich in Ca and K but with low contents of P and organically bound Si, the bed layer formation is initiated by reactions of gaseous or liquid K compounds with the surface of the bed material grains, resulting in the formation of a potassium silicate melt. The last process is accompanied by the diffusion/dissolving of Ca into the melt and consequent viscous flow sintering and agglomeration. The addition of high enough phosphorus content to convert the available fuel ash basic oxides into phosphates reduced the amount of K available for the reaction with the quartz bed material grains, thus preventing the formation of an inner bed particle layer in the combustion of logging residues, bark, and willow. Some of the phosphate-rich ash particles, formed during the fuel conversion, adhered and reacted with the bed material grains to form noncontinuous phosphate−silicate coating layers, which were found responsible for the agglomeration process. Adding phosphorus-rich fuels/additives to fuels rich in K and Si (e.g., wheat straw) leads to the formation of alkali-rich phosphate−silicate ash particles that also adhered to the bed particles and caused agglomeration. The melting behavior of the bed particle layers/coatings formed during combustion of phosphorus-rich fuels and fuel mixtures is an important controlling factor behind the agglomeration tendency of the fuel and is heavily dependent on the content of alkaline earth metals in the fuel. A general observation is that phosphorus is the controlling element in ash transformation reactions during biomass combustion in fluidized quartz beds because of the high stability of phosphate compounds.

  • 402.
    Grimm, Alejandro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Skoglund, Nils
    Umeå universitet.
    Eriksson, Gunnar
    Boström, Dan
    Umeå universitet.
    Boman, Christoffer
    Umeå universitet.
    Öhman, Marcus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Effekter av fosfortillsats vid förbränning av biomassa2010Rapport (Annet vitenskapelig)
    Abstract [sv]

    Resultaten från försöken visar att fosforrika additiv kan vara intressanta för att reducera beläggningsbildning och högtemperaturkorrosion utan att i någon större omfattning öka slaggnings- och bäddagglomereringstendensen hos typiska biobränslen. För att erhålla en märkbar positiv effekt av kaliumbindning till fosfater krävs att mängden kalcium och magnesium i den slutgiltiga bränslemixen inte är alltför hög relativt mängden fosfor, då framför allt Ca men till viss del även Mg reagerar med P innan K binds in effektivt. Generellt behövs troligen inblandningsgrader motsvarande en molkvot P/(K+Na+2/3Mg+2/3Ca) i bränslemixen som närmar sig 1. För att erhålla en molkvot på 1 i ett typiskt halm-, salix- eller grotbränsle innebär det i praktiken en fosfortillsats motsvarande 12, 4.7 respektive 3.7 gram rent P per kg torrt bränsle.

  • 403.
    Grimm, Alejandro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Öhman, Marcus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lindberg, Therese
    LKAB.
    Fredriksson, Andreas
    LKAB.
    Boström, Dan
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Bed agglomeration characteristics in fluidized bed combustion of biomass fuels using olivine as bed material2012Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 26, nr 7, s. 4550-4559Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The bed agglomeration characteristics during combustion of typical biomass fuels were determined in a bench-scale bubbling fluidized bed reactor (5 kW) using olivine and quartz sand as bed material. The fuels studied include willow, logging residues, wheat straw, and wheat distiller’s dried grain with solubles (wheat DDGS). Bed material samples and agglomerates were analysed by means of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), for morphology and elemental composition. Furthermore, bed ash particles were separated by sieving from the bed material samples and analyzed for elemental composition by SEM-EDS and for determination of crystalline phases by powder X-ray diffraction (XRD). Chemical equilibrium calculations were performed to interpret the experimental findings of layer formation and reaction tendencies in both bed materials. Significant difference in the agglomeration tendency between olivine and quartz was found during combustion of willow and logging residues. These fuels resulted in inner layers that were more dependent on the bed material composition, and outer layers that have a composition similar to the fuel ash characteristics. The elemental composition of the inner layer formed on the quartz bed particles was dominated by Si, K and Ca, whereas for the olivine case consisted mainly of Mg, Si and Ca. Chemical equilibrium calculations made for both bed materials showed a low chemical driving force for K to react and be retained by the olivine bed particles, which is in accordance to the experimental findings. For the quartz case, the inner layer was found responsible for the initiation of the agglomeration process. The composition of the fewer and more porous agglomerates found after the experiments in olivine bed showed neck composition and characteristics similar to the individual bed ash particles found in the bed or outer bed particle coating composition. For DDGS (rich in S, P, K and Mg) and wheat straw (rich in Si and K), no significant differences in the bed agglomeration tendency between olivine and quartz bed materials were found. The results show that the bed particle layer formation and bed agglomeration process were associated to direct adhesion of bed particles by partly molten fuel ash derived K-Mg-phosphates for DDGS, and K-silicates for wheat straw.

  • 404.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    BioDRI: Skogen möter stålet: Förgasa biomassa. Använd gasen för att göra järn (DRI)2015Konferansepaper (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    •Processkedja i stort, projektstruktur, parter•WP1: Försörjning: hur får vi fram biomassan•WP2: Förgasningsprocess, Pilotförsök m.m.•WP3: Reduktionsprocesser•WP4: Hela kedjan•Diskussion och slutsatser

  • 405.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Simple model for prediction of temperatures in an L-shaped tundish: verification by continuous temperature measurements1998Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 38, nr 7, s. 704-713Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple model concept developed for the SSAB steel plant was tested on data for another plant. That plant had an L-shaped tundish for billet casting. A special tanks in series model was developed for the steel flow in that tundish. The rest of the model could be used without change. It consists of simple equations for heat loss in ladle and tundish, as well as for the effect of thermal stratification and drainage flows in the ladle. The model was verified against existing data from continuous temperature measurements. The results show that the model approach developed for the steel plant of SSAB can also give good predictions with a different plant and tundish design. A simple mixing model could be used even for a complicated tundish configuration

  • 406.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Steel and sustainability - a Scandinavian perspective: Sustainability2004Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A description is given on the practice in the Steel Plant of SSAB Tunnplåt AB in Luleå and on the progress in recirculation of residuals and decreasing environmental impact. An extensive study on greenhouse gas in steel production up to slabs was carried out by SSAB during the years 2000-2002. Present and new processes and possible alternatives were studied, as well as the effect of the product programme. Different emission alternatives were studied using global calculation (SSAB + CHP plant). Conclusions on long-term and shortterm possibilities were discussed. Major efforts have been made to develop the process integration technology. In Sweden, this has been realised within a national programme for the total process industry (steel, pulp and paper, petrochemicals, food). There are synergies, as the optimisation problem itself is relatively similar independent of industry sector. Similar efforts are made in other Scandinavian countries and a joint Scandinavian programme has been carried out. Discussions on ore-based vs. scrap-based metallurgy are often based on the assumption that these roads are alternatives to each other. This is not the case; instead, ore-based metallurgy is the first step in a series of subsequent life cycles, and both roads are necessary to carry out the "cycle of cycles". The philosophy of this is discussed. The Scandinavian climate makes the use of residual heat energy for district heating and cooling economically important and a part of energy/sustainability considerations. Significant R&D efforts are and have been made to increase recirculation. Two programmes/ centres of excellence in this field are described.

  • 407.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Steel and sustainability: Scandinavian perspective2005Inngår i: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 32, nr 3, s. 235-241Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A description is given of practice at the steelplant of SSAB Tunnplat AB in Lulea, Sweden, and of progress in the recycling of residuals and reducing environmental impact. An extensive study of greenhouse gases in steel production to slabs was carried out by SSAB during the years 2000-02. Current and new processes and possible alternatives were studied, as well as the effect of the product programme. Various emission alternatives were considered using a global calculation (SSAB plus combined heat and power (CHP) plant), and conclusions for long term and short term possibilities were discussed. Major efforts have been made recently to develop process integration technology. In Sweden, this has been realised within a national programme for the total processing industry (steel, pulp and paper, petrochemicals, food). There are synergies, as the optimisation problem itself is relatively similar, independent of industry sector.

  • 408.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Use of injection treated material for sections and universal flats1983Inngår i: Proceedings: Scaninject III ; 3rd international conference on refining of iron and steel by powder injection, Luleå, Sweden, June 15-17, 1983 ; [organized jointly by MEFOS, Jernkontoret], Luleå: MEFOS , 1983, s. 1-40Konferansepaper (Fagfellevurdert)
  • 409.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Andersson, Göran
    Jernkontoret.
    Management of energy challenges at SSAB Tunnplåt AB, the largest steel producer of strip products in Scandinavia2005Inngår i: Proceedings of the International Green Energy Conference: 12-16 June 2005, Waterloo, Ontario, Canada, Waterloo, Canada: Univ. of Waterloo, Dept. of Mechanical Engineering , 2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The integrated steel plant of SSAB Tunnplåt AB is situated in two locations with a distance of 800 km between the steel plant and the rolling mill. Thus, integrated energy management between steel making and rolling is not practically possible. Instead, in both locations, substantial efforts have been invested in local integration between the energy systems of the plant areas and those of the surrounding communities. This has caused a need for special knowledge in several fields: new technologies, process integration, environment andemissions etc. This has been studied in own R&D, but SSAB Tunnplåt AB has also initiated and/or contributed to several cooperative efforts on the national Nordic and international scale. Some projects and results are described

  • 410.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dahl, Jan
    Söderström, Mats
    Linköpings universitet.
    Exergy as a means for process integration in integrated steel plants and process industries2009Inngår i: Stahl und Eisen (1881), ISSN 0340-4803, Vol. 129, nr 9, s. 2-8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Exergy analysis can be a useful tool for process comparison and improvement in industrial energy systems. Examples from three branches are given: pulp and paper, bio refineries (ethanol) and steel production. The application and development of exergy analysis in an integrated steel plant is shown together with description and explanations on destroyed and lost exergy. Implementation for energy conservation and use as a pedagogic tool is discussed.

  • 411.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Elfgren, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Söderström, Mats
    Linköping University, Energy Systems.
    Thollander, Patrik
    Linköping University, Energy Systems.
    Berntsson, Thore
    Chalmers University of Technology, Department of Energy and Environment, Division of Heat and Power Technology.
    Åsblad, Anders
    CIT Industriell Energi.
    Wang, Chuan
    Swerea MEFOS AB.
    Possibilities and problems in using exergy expressions in process integration2011Inngår i: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011): 9-13 May, Linköping, Linköping: Linköping University Electronic Press, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Industrial energy systems are complicated networks, where changes in one process influence its neighboring processes. Saving energy in one unit does not necessarily lead to energy savings for the total system. A study has been carried out on the possibility to use the exergy concept in the analysis of industrial energy systems. The exergy concept defines the quality of an amount of energy in relation to its surrounding, expressing the part that could be converted into work. The study consists of literature studies and general evaluations, an extensive case study and an interview study. In the latter it was found that non technical factors are major obstacles to the introduction of exergy.

  • 412.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Harvey, Simon
    Chalmers University of Technology, Department of Energy and Environment, Division of Heat and Power Technology.
    Isaksson, Johan
    Chalmers University of Technology, Department of Energy and Environment, Division of Heat and Power Technology.
    Karlsson, Jonny
    SSAB EMEA, Luleå.
    Possibilities to implement pinch analysis in the steel industry: a case study at SSAB EMEA in Luleå2011Inngår i: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011): 9-13 May, Linköping, Linköping University Electronic Press, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Steelmaking is an energy intensive industry. Much development work has been accomplished during the past years to make the processes more efficient. Process integration has come to play an important role for identifying efficiency measures, using mathematical programming as general tool. So far only a few minor process integration studies using pinch analysis have been made in this type of industry, and only on smaller subsystems.This paper presents the results of a pinch targeting study that was conducted at the Swedish steel making company SSAB EMEA in Luleå. The pinch analysis methodology was originally developed to study heating, cooling and heat exchange in process systems with many streams. In the steel industry there arerelatively few streams that are appropriate for heat exchange. This limits the use of pinch analysis. However, this study demonstrates that pinch analysis is a powerful tool for certain subsystems, especially the gas cleaning unitof the coke plant. The paper includes several suggestions for improved energy efficiency in this section of the steel plant.

  • 413.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Isaksson, Johan
    Chalmers University of Technology.
    Harvey, Simon
    Chalmers University of Technology.
    Nilsson, Leif
    SSAB EMEA, Luleå.
    Application of pinch analysis in an integrated steel plant in northern Sweden2013Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, nr 7, s. 1202-1210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The energy system in a modern integrated steel plant is a complicated network of units exchanging energy and matter with each other. System studies using process integration tools are important to avoid sub-optimization. At the steel plant in Luleå such studies have been carried out using a MILP-based mathematical programming tool (reMIND), mainly because of its inherent flexibility for handling combined flows and reactions of both matter and chemical, thermal and mechanical energy. There are, however, areas where the energy system is dominated by creation, transport and exchange of thermal energy, and where pinch analysis can be expected to be a valuable tool. For this reason a pinch targeting study was carried out for the plant site of the integrated steel plant in Luleå. The coke plant and the iron making/steelmaking plant were both studied with three ambition levels of possible improvements. The study confirmed that pinch analysis is a powerful tool for targeting energy savings in areas where thermal energy flows dominate the local energy system, e.g., the gas cleaning area at the coke plant. The study also indicated that a connection between the energy systems in the coke plant and the iron making/steelmaking would be valuable. This is not 100% feasible because of distance, but, a common steam net could add a degree of flexibility.

  • 414.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Jonsson, Kjell Olof
    SSAB Tunnplåt AB.
    Eriksson, Sven
    SSAB Oxelösund AB.
    Jonsson, Lage
    Swerea MEFOS AB.
    Jönsson, Pär
    Kungliga tekniska högskolan, KTH.
    Pan, Yuhua
    Luleå tekniska universitet.
    Theoretical and practical study of thermal stratification and drainage in ladles of different geometry1999Inngår i: SCANMET I: 1st International Conference on Process Development in Iron and Steelmaking, 7-8 June 1999, Luleå, Sweden, Nordkalott Hotell-Konferens, Luleå: MEFOS , 1999, Vol. 2, s. 101-117Konferansepaper (Fagfellevurdert)
  • 415.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Jonsson, Kjell-Olov
    SSAB.
    Eriksson, Sven
    SSAB Oxelösund AB.
    Jonsson, Lage
    Swerea MEFOS AB.
    Jönsson, Pär
    Department of Metallurgy, Royal Institute of Technology, Stockholm.
    Pan, Yuhua
    Luleå tekniska universitet.
    Theoretical and practical study of thermal stratification and drainage in ladles of different geometry2000Inngår i: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 29, nr 1, s. 30-38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    SSAB Luleå, SSAB Oxelösund, MEFOS and Luleå University of Technology have cooperated in developing theoretical models for prediction of thermal stratification and drainage in steel ladles. Predicted results have been verified by measurements done in production ladles with heat weighs of 105 and 200 tonne as well as in a 7-tonne pilot plant ladle. The thermal stratification was measured by thermocouples at different depths. The drainage flow was studied by means of tracer experiments. Numerical simulation models of the steel flow were developed for 7, 105 and 200 tonne steel ladles. The agreement between predictions and measurements was found to be good. The conclusion is that CFD simulation gives a good prediction of stratification and drainage flows in production ladles.

  • 416.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Jonsson, Lage
    Luleå tekniska universitet.
    Physical behaviour of slag in a 107-tonne ladle: production scale experiments and theoretical simulation2003Inngår i: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 32, nr 3, s. 113-122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The combined movement of steel, slag and gas in a ladle has been studied with the aid of a multiphase CFD model and measurements in production scale. Comparison of model data and measurements in a production ladle has been carried out for three cases: The 'open eye' created during gas stirring, the mixing of top slag during gas stirring in the CAS-OB and finally for studying sculling phenomena. It was found that the simulated 'open eye' appears as a central slag-free zone with a surrounding 'splash zone' characterized by the fact that steel is found on top of the slag. The simulated 'open eye' corresponds to the 'splash zone'. The predicted gas stirring in CAS-OB gives an efficient stirring of the top slag also. This was confirmed by noting that slag samples taken from the ladle seem to be representative of the mean slag composition. Finally, streamlines during stirring have been compared with sculling and wear observed in the production ladle. Good agreement was obtained

  • 417.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Jonsson, Lage
    Swerea MEFOS AB.
    Jonsson, Pär
    Department of Metallurgy, Royal Institute of Technology, Stockholm.
    Jonsson, Kjell Olof
    SSAB Tunnplåt AB.
    Numerical prediction and experimental verification of thermal stratification during holding in pilot plant and production ladles1999Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 39, nr 7, s. 715-721Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 3-dimensional CFD-model has been developed to simulate the natural convection flow in ladles. Qualified measurements of temperature and velocities in 107 and 7 tonne ladles have been made to verify the model. The downward convection flow at the ladle wall has been studied using radioactive isotopes and the thermal stratification has been studied by means of continuous temperature measurements. The experimental techniques are complex and additional numerical simulations have been carried out to study the effect of the measurement technique on the measurement error. The result indicates that the measurements are of sufficient accuracy for the validation. The measurements are compared to predictions from the numerical model. The main conclusion is that the theoretical CFD model gives a very accurate estimation of the temperature distribution during holding

  • 418.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Jonsson, Lage
    Swerea MEFOS AB.
    Jönsson, Pär G.
    Ovako Steel AB.
    Prediction of emptying flows in ladles and verification with data from trace element plant trials1997Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 37, nr 11, s. 1081-1090Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A three-dimensional mathematical model of a casting ladle based on fundamental transport equations has been developed. The model may be used for predictions of both a standing ladle and a ladle from which steel is teemed into a tundish. An additional feature of the model is that it can predict concentration profiles of tracer elements which are added to the steel. The predicted concentration profiles during teeming are compared to experimental data from plant trials performed at SSAB and the agreement is found to be good. The model is used as a tool in the development of process control models.

  • 419.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Jonsson, Lage
    Pan, Yuhua
    Olika, Bekele
    Stratification and emptying flow in ladles before and during casting: creation of simple models from experiments and sophisticated models1997Inngår i: 56th Ironmaking Conference proceedings : Chicago meeting, April 13 - 16, 1997, Warrendale, Pa.: Iron and Steel Society , 1997, s. 625-646Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper describes the development and verification of simple models for predicting the effect of thermal stratification and drainage flow on the temperature of the steel leaving the ladle. Two types of models have been developed and tested: one based on tanks in series and one based on equations. The tanks in series model is more complex than the equation model. However, both models are simple enough to be possible for process control. The equation model is formulated so that the total effect of stratification and drainage is expressed with one parameter. Experiments with tracer addition were performed for verification as well as 3-D numerical simulations. Both models give good predictions for the conditions that were studied

  • 420.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lampinen, Hans-Olof
    SSAB Tunnplåt AB.
    Lundqvist, Magnus
    Luleå tekniska universitet.
    Videhult, Sebastian
    Kwaerner Turbin AB, Kristinehamn.
    Determination of thermal stratification and emptying flow in ladles by continuous temperature measurement and tracer addition1996Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 36, nr Supplement, s. S211-S214Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    If we want to control and predict the temperature of steel in the tundish we must know the thermal stratification in the ladle before and during casting, as well as the interaction with the steel flow through the nozzle. A group project, with participation of SSAB (Luleå and Oxelo̊sund), Luleå University and MEFOS, has been carried out to study these phenomenon. The stratification in the ladle was measured by thermo-couples penetrating into the melt at different levels. Such measurements were carried out before and during casting. To get information about the drainage flow, studies were made with tracer elements added at different points in the ladle. The response, defined as the tracer concentration in the outlet stream from the ladle, was measured by frequent sampling. Model work by numerical simulation and with tanks in series is discussed briefly

  • 421. Grip, Carl-Erik
    et al.
    Larsson, Mikael
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Energy optimization by means of process integration in an integrated steel plant with surrounding community2001Inngår i: 84th Steelmaking Conference proceedings: Baltimore, Maryland, March 25 - 28, 2001 / [ed] David L. Kanagy, Warrendale, Pa, 2001Konferansepaper (Fagfellevurdert)
  • 422.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Mikael
    Harvey, Simon
    Chalmers University of Technology, Department of Energy and Environment, Division of Heat and Power Technology.
    Nilsson, Leif K.
    SSAB EMEA, Luleå.
    Process integration: tests and application of different tools on an integrated steelmaking site2013Inngår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 53, nr 2, s. 366-372Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The energy network in Luleå consists of the steel plant, heat and power production and district heating. Global system studies are necessary to avoid sub-optimization and to deliver energy and/or material efficiency. SSAB began work with global simulation models in 1978. After that several more specialized process integration tools have been tested and used: Mathematical programming using a MILP method, exergy analysis and Pinch analysis. Experiences and examples of results with the different methods are given and discussed. Mathematical programming has been useful to study problems involving the total system with streams of different types of energy and material and reaction between them. Exergy is useful to describe energy problems involving different types of energy, e.g. systematic analysis of rest energies. Pinch analysis has been used especially on local systems with streams of heat energy and heat exchange between them.

  • 423.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lundmark, Robert
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Samhällsvetenskap.
    Alriksson, Stina
    University of Kalmar.
    Possibilities for combined evaluation of social, economic energy/environmental values2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Northern Scandinavia is an area, which is rich in natural resources and energy-intensive base industries covering several branches, e.g., Mining, Iron and Steel, Metal production, Pulp and Paper. They are often part of a community network where a change in one node affects the behavior and efficiency of its neighbors.  Improvements in environmental load, energy efficiency etc. cannot simply be achieved by improving the individual units. A system approach is needed. Such methods (Process Integration) have been developed within the Nordic Countries for more than twenty years, e.g. within the Swedish national program that was launched 1989. They are been practically applied e.g. at SSAB in Luleå An excellence center for Process Integration in Steelmaking (PRISMA), with industrial partners from Sweden and Finland, has recently been founded at MEFOS in Luleå. The process integration methods have been developed to handle multi-objective problems. This is because the industry has to answer to a combined demand on energy consumption, emission limits for several substances, climate effects as well as costs.  For regional evaluation an economic model has been developed which explicitly returns changing input and output prices due to changes in e.g., production technology, derived input demand or the introduction of market instruments. Especially on smaller regional markets, changes in input demand of fibrous raw material might significantly affect its price. This price effect must be considered whenever extensive changes in the production process are considered so that the project is not, ex post, rendered unprofitable. Another factor of great influence is local and national attitudes. These can influence both market value and political decisions.  These effects can be evaluated in stakeholder studies. Co-evaluation with the technical parameters mentioned above is interesting, but an obstacle is the difference in result format.  A method (CONJOINT) has been developed, by which these results can be converted into numerical parameters. For the Swedish Steel industry it has been tested within the ECO-Cycle program. An attempt to merge these methods into a combined study is presently carried an ongoing PROCESS INTEGRATION study for a Pulp and paper mill in northern Sweden. The possibility to merge into a combined tool or methodology is discussed.

  • 424.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Mukka, S.
    Seger, M.
    Wahlberg, H.
    Relining a BOF in 60 hours1998Inngår i: Steel Times, ISSN 0039-095X, Vol. 226, nr 8, s. 282-283Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Discusses SSAB Tunnplat AB's development of a system for fast relining of converters in refractories. Requirements of the method; Technique for relining; Main features of the BOF plant; Example of a 60-hour schedule used during planning a reline.

  • 425.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Salman, Hassan
    HKSE Energy Consulting, Sveaskog.
    Ritzen, Ola
    AGA AB/Linde Gas.
    Andersson, Lars I.
    Billerudkorsnäs AB.
    Tottie, Magnus
    LKAB.
    Robisnsson, Ryan
    Höganäs AB.
    Winnika, Henrik
    Energy Technology Centre, Piteå.
    Östman, Marianne
    Swerea MEFOS AB.
    BioODRI: forestry meets steel: A techno-economic study on us of biomass gasification to produce a gas sutiable for production of CO2 lean iron2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A major part of the world’s iron production is presently using fossil reductants. The climate effect would be improved if renewable raw material could be used instead. One way could be to gasify biomass and use the gas to produce DRI (Direct reduced Iron). This is studied in a cooperative project. LTU, MEFOS, ETC and five industries in the areas forestry & pulp, mining, iron and gas are involved. The production chain Biomass production and distribution-Gasification-DRI production-DRI use is investigated in four work packages: WP1: Biomass supply, WP2: Gasification, WP3: Metallurgical processes and WP4: Process integration. The paper will focus on the studies and modeling of biomass supply, harvesting and transport and gasification as well as on the system studies. The use of the gas in the metallurgical application is briefly described as background.

  • 426.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Sandström, Erik
    Gebart, Rikard
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Karlsson, Jonny
    Industrial ecology in northern areas: practical experience and development2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The possibilities to develop the industrial ecology in the northern regions of Europe are influenced by some common characteristics, e.g.: The regions are rich in natural re-sources and energy- and material intensive base industries. These industries cover sev-eral branches, e.g., Mining, Iron and Steel, Metal production, Pulp and Paper. Low popu-lation density and relatively long distances to the main customers are difficulties espe-cially for transport and use of rest products. District heating with waste heat from the in-dustries is an important part of the energy system that reduces the emission of green-house gases and improves the overall energy efficiency. The problems and possibilities connected to the industrial ecology are described for two examples, the energy system in Luleå and the Solander science park in Piteå

  • 427.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Sperle, Jan-Olof
    Applications of HSLA steels for beams and small flats1984Inngår i: HSLA steels technology & [and] applications: conference proceedings of International Conference on Technology and Applications of HSLA Steels, October 1983, Philadelphia, Pa., Metals Park, Ohio: ASM International, 1984, s. 1115-1127Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The metallurgy of these steels is discussed. User problems and solutions are discussed for steel construction, the automotive industry, shipbuilding, offshore and the workshop industry. Optimum strength with respect to plastic deformation, deflection, instability and fatigue is discussed. Some examples of optimal designs are given.

  • 428.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Söderström, Mats
    Linköpings universitet.
    Berntsson, Thore
    Chalmers University of Technology.
    Process integration as a general tool for energy-intensive process industry: development and practical applications in Sweden2008Inngår i: SCANMET III: 3rd International Conference on Process Development in Iron and Steelmaking, 8-11 June 2008, Luleå, Sweden, Luleå: MEFOS , 2008, Vol. 1, s. 223-232Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Sweden and Scandinavia are situated in an area, which is rich in natural resources. Energy-intensive base industries using a combination of these and imported resources are a dominant part in Swedish economy. They cover several branches, e.g. Iron and Steel, Metal Production, Pulp and Paper, Chemical Industry. There are differences, e.g. the temperature of the solvent is different between processes. However, the similarities in problem structures are striking in questions regarding general structural decisions, energy system behavior and system optimization. For these reasons, a national program has been carried out to develop common PROCESS INTEGRATION tools for use in these branches. The Swedish Energy Agency and the industry have financed the program. The initial scope was used for energy optimization and conservation, but has been broadened to also include economy, environment and climate gas emissions. Methods based on pinch analysis, exergy analysis or mathematical programming have been developed and put to use. Some projects involve Scandinavian and international cooperation e.g. through IEA. Some specific examples are discussed in the paper: Development of a PROCESS INTEGRATION tool for steel industry. In this case mathematical programming has been found to be the most appropriate method. Use of a tool developed in one branch in another type of industry. International project (IEA) on systems integration between society and industry including cogeneration and power plants." Reduction of climate gas emissions on the boundary industry/energy market. Great efforts are being made to find the optimal compromise between simplicity and performance as well as on transfer of results and knowledge to industrial users. The financial support of the SCANMET conference and its energy sessions are part of that effort.

  • 429.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Tivelius, Bertil
    Sohlgren, Thomas
    Gossas, Peter
    Ladle metallurgy in SSAB (Oxelösund, Domnarvet and Lulea)1980Inngår i: Proceedings: Scaninject II ; 2nd international conference on injection metallurgy, Luleå, Sweden, June 12-13, 1980, Luleå: MEFOS , 1980, s. 1-13Konferansepaper (Fagfellevurdert)
  • 430.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Toffolo, Andrea
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Salman, Hassan
    HKS Energy, Sveaskog.
    Andersson, Lars I.
    Billerudkorsnäs AB.
    Ritzen, Ola
    AGA AB/Linde Gas.
    Tottie, Magnus
    LKAB.
    Robinnsson, Ryan
    Höganäs AB.
    Winnikka, Henrik
    Energy Technology Centre, Piteå.
    Östman, Marianne
    Swerea MEFOS AB.
    Sandberg, Erik
    Swerea MEFOS AB.
    Forestry meets steel: a technoeconomic study of the possible DRI production using biomass2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The possibility to produce DRI using gasified Biomass is studied in a cooperative project. LTU, MEFOS, ETC and five industries in the areas forestry & pulp, mining, iron and gas are involved. The production chain Biomass production and distribution -Gasification-DRI production-DRI use is investigated in four work packages:WP1: Biomass supply: A large amount of Biomass has to be delivered into a single site to exchange a large amount of fossil reductant. It is important to use forestry by- products as a major part of round wood is reserved for other uses. Harvesting, logistics and economics have to be considered. Available data were collected and used to make a system model on harvesting treatment and transport. The simulations indicated that the supply of residuals is possible but will need material from a large part of the north Sweden wood area. WP2: Gasification. The aim is to use to produce hot gas that can be used directly. Pilot experiments are carried out using oxygen in an entrained flow gasifier. WP3: Metallurgical processes. Reduction tests are carried out with gas that can be produced in the gasifier. The limitations of the gas content are studied as well as the effect on DRI. Also the suitability of the DRI product is evaluated WP4: Process integration. A system model is built using the results from work packages 1-3 and used for technical economic optimization the whole system harvesting-transport-gasifier-direct reduction- use of DRI. The process chain is technically possible; however there are problems to be solved, e.g., gas quality vs. demands from DRI process, Biomass supply and logistics. The result is important to evaluate for industrial application, but also to get information of the effect of different governmental control instruments.

  • 431.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Toffolo, Andrea
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Östman, Marianne
    Swerea MEFOS AB.
    Sandberg, Erik
    Center for Process Integration in Steelmaking, Swerea MEFOS, Luleå, Luleå tekniska universitet.
    Orre, Joel
    Swerea MEFOS AB.
    Forestry meets Steel: A system study of the possibility to produce DRI (directly Reduced Iron) using gasified biomass2015Inngår 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 , 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The main production of primary Iron from ore is now made by reduction using fossil reductants, either by producing hot metal in the blast furnace process or as directly reduced iron with natural gas as most common reductant. The climate gas impact would be improved if at least part of the reductants could be produced from Biomass. One possibility could be to use gasified Biomass to produce DRI (Directly Reduced Iron). This is studied in a cooperative project where LTU, MEFOS, ETC and five industries in the areas forestry & pulp, mining, iron and gas are involved. The investigation is made in four parts where the first one is on the supply of biomass. A large amount of Biomass has to be delivered into a single site to exchange a large amount of fossil reductant. Also, forestry by-products should be used as most of the round wood is reserved for other uses. Harvesting, logistics and economics are considered. The second part is on the gasification of the biomass, where the aim is to use to produce hot gas that can be used directly. Pilot experiments are carried out using oxygen in an entrained flow gasifier. The third part is on the metallurgical processes, where reduction tests are carried out with gas that can be produced in the gasifier. The limitations of the gas content are studied as well as the effect on DRI. Also the suitability of the DRI product is evaluated. The fourth part of the project uses process integration to model the whole process chain. The results from the other project parts are used to build the system model. It is then used for technical economic optimization the whole system harvesting-transport-gasifier-direct reduction-use of DRI. The first use of the system model has been to find the best supply road (harvesting, pretreatment and transport) for a chosen production case The simulations indicated that the supply of residuals is possible but will need material from a large part of the north Sweden wood area, and that a relatively large amount of gas recirculation is needed. The continuing work is focused on further development of the optimization tool and the use of it for more extensive studies of the trade-off between parameters of metallurgy, gasification and supply. The result can be important for evaluation of future industrial applications. It could also help in understanding the effect of governmental control instruments. The paper will mainly focus on the process integration study.

  • 432.
    Grip, Carl-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Öhman, Stig
    Luleå tekniska universitet.
    Nilsson, Christer
    SSAB Tunnplåt AB.
    Johansson, Håkan
    Tanks in series model with dynamic shortcut flows for a straight tundish: Verification by tracer experiments on production heats1998Inngår i: High Temperature Materials and Processes, ISSN 0334-6455, E-ISSN 2191-0324, Vol. 17, nr 3, s. 177-192Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Production control must have accurate models for the prediction of tundish temperature to meet increasing demands on control and production rate in continuous casting. The models have to be simple. They must also include the effect of variations in steel flow and mixing, including shortcut flows from the inlet stream towards the outlet end. To meet this demand, a tank in series model was designed, which also included the effect of dynamic shortcut flows. The model has been verified by data from experiments with chemical tracers in a 14 tonne straight tundish. The tracers have been added both in the ladle and close to the inlet end in the tundish and the response in the steel entering the mould has been died. The data seem to confirm that there is a different distribution of the steel flow in the period shortly after the ladle change. The difference could be explained either as shortcut flows caused by buoyancy or by increased stirring. It is possible to choose a configuration of tanks that allows simulation of both the transient behaviour at ladle change and the steady state conditions during the main part of the casting by changing the adjustable parameters for the shortcut flow without changing the configuration of tanks

  • 433.
    Grip, Niklas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Nilsson, Leif
    SSAB EMEA, Luleå.
    Wavelet study of dynamic variations in steel and ironmaking rest gases: Potential effect on external use2013Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, s. 1032-1040Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The surplus energy in rest gases is an important by-product in the SSAB EMEA steel plant in Luleå. The surplus is used in a local heat and power plant. Studies have been and are being carried out to find alternative use for the high calorific gases, especially the coke oven gas. The different gas flows typically are mixtures of irregularly distributed transients and non-periodic contents of different duration. Slowly varying fluctuations can probably be parried by good production planning. For shorter wavelengths some kind of safety margin could be appropriate, perhaps in the range 0.75–1.5 kN m3/h. However, the existing buffer capacity in gasholders, etc. is too small to cover the fluctuations. Good production planning can partly compensate low buffer capacity. An example from a period without gas holder is discussed.We describe analysis of the gas flows that can be used both for better production planning and for efficient external use, e.g., for fuel production. Rather than traditional Fourier analysis, we use wavelet analysis, which is better suited for analyzing the irregular and nonperiodic characteristics of the gas flows. We demonstrate such analysis on collected gas flow data from the SSAB EMEA steel plant and give some suggestions for how to make a good choice of wavelet basis for the analyzed signals.

  • 434.
    Grönkvist, Stefan
    et al.
    Department of Chemical Engineering and Technology, Division of Energy Processes, Royal Institute of Technology.
    Möllersten, Kenneth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. International Institute for Applied Systems Analysis, Laxenburg, Austria.
    Pingoud, Kim
    Finnish Forest Research Institute.
    Equal opportunity for biomass in greenhouse gas accounting of CO 2 capture and storage: a step towards more cost-effective climate change mitigation regimes2006Inngår i: Mitigation and Adaptation Strategies for Global Change, ISSN 1381-2386, E-ISSN 1573-1596, Vol. 11, nr 5-6, s. 1083-1096Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbon dioxide capture and permanent storage (CCS) is one of the most frequently discussed technologies with the potential to mitigate climate change. The natural target for CCS has been the carbon dioxide (CO2) emissions from fossil energy sources. However, CCS has also been suggested in combination with biomass during recent years. Given that the impact on the earth's radiative balance is the same whether CO2 emissions of a fossil or a biomass origin are captured and stored away from the atmosphere, we argue that an equal reward should be given for the CCS, independent of the origin of the CO2. The guidelines that provide assistance for the national greenhouse gas (GHG) accounting under the Kyoto Protocol have not considered CCS from biomass (biotic CCS) and it appears that it is not possible to receive emission credits for biotic CCS under the first commitment period of the Kyoto Protocol, i.e., 2008-2012. We argue that it would be unwise to exclude this GHG mitigation alternative from the competition with other GHG mitigation options. We also propose a feasible approach as to how emission credits for biotic CCS could be included within a future accounting framework

  • 435.
    Gu, Irene
    et al.
    Chalmers University of Technology, Department of Signals and Systems.
    Berlijn, Sonja M.
    Statnett, Oslo.
    Gutman, Igor
    STRI AB, Ludvika.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Practical applications of automatic image analysis for overhead lines2013Inngår i: 22nd International Conference and Exhibition on Electricity Distribution (CIRED 2013): Stockholm, Sweden, 10 - 13 June 2013, Red Hook, NY: Curran Associates, Inc., 2013, artikkel-id 560Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes novel techniques for automatically extracting information from overhead lines based on automatic image/video processing. Three application scenarios are presented: (a) detecting snow and ice coverage on insulators for overhead lines; (b) detecting swing angles of insulators; (c) quantifying the visibility of insulators at transmission lines with typical backgrounds. Experiments have been conducted on recorded videos/images of insulators (with different prototypes) for overhead lines in a remote test station in Norway. Results show that the proposed automatic image analysis methods are promising for extracting the status (snow/ice coverage, swing angle, visibility) of insulators and might be applied in the future for other components of the overhead line.

  • 436.
    Gu, I.Y.H.
    et al.
    Chalmers University of Technology.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Estimating interharmonics by using sliding-window ESPRIT2008Inngår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 23, nr 1, s. 13-23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method is proposed for estimating interharmonic frequencies in power system voltage and current signals. The method is based on a spectrum-estimation method known as "estimation of signal parameters via rotational invariance techniques" (ESPRIT). To allow for a more reliable spectral estimation and to cover nonstationarity in the signal, a sliding-window version of ESPRIT is introduced. This paper describes the basic ESPRIT method as well as sliding-window ESPRIT. The paper discusses the application of the method to one synthetic signal and three measurement signals. It is shown that the method allows for very accurate frequency estimation of interharmonic components. The limitations of the methods, such as line splitting and spurious components, can be overcome by using the coherent information obtained from the sliding-window method. A number of remaining issues are also discussed in this paper.

  • 437.
    Gu, I.Y.H.
    et al.
    Chalmers University of Technology, Department of Signals and Systems.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Le, C.D.
    Chalmers University of Technology, Department of Signals and Systems.
    Signal processing and classification tools for intelligent distributed monitoring and analysis of the smart grid2012Inngår i: 2nd IEEE PES International Conference and Exhibition on Innovative Smart Grid Technologies (ISGT Europe): [Dec. 5-11, 2011, Manchester, United Kingdom], Piscataway, N.J: IEEE Communications Society, 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes a novel framework for an intelligent monitoring system that supervises the performance of the future power system. The increased complexity of the power system could endanger the reliability, voltage quality, operational security or resilience of the power system. A distributed structure for such a monitoring system is described and some of the advanced signal processing techniques or tools that could be used in such a monitoring system are given. Several examples for seeking the spatial locations and finding the underlying causes of disturbances are included

  • 438.
    Gullberg, Monica
    et al.
    Royal Institute of Technology, Avdelningen Byggnadsteknik.
    Ilskog, Elisabeth
    Luleå tekniska universitet.
    Katyega, Maneno
    Tanzania Electric Supply Company Ltd.
    Kjellström, Björn
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Village electrification technologies: an evaluation of photovoltaic cells and compact fluorescent lamps and their applicability in rural villages based on a Tanzanian case study2005Inngår i: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 33, nr 10, s. 1287-1298Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrification of remote sites in developing countries is often realised trough diesel generator sets and an electric distribution network. This was also the technology used in the village Urambo, where the first rural electrification co-operative in Tanzania was started in 1994. Climate change however calls for decreased fossil fuel combustion worldwide and new technologies have been further developed since the erection of the diesel generator sets in Urambo. It is therefore not obvious that electrification of other rural areas shall follow the Urambo example. In this article, the situation for 250 electricity consumers in Urambo will be demonstrated and the implications for them of introducing new technologies will be evaluated. Technology options regarded in the study are individual photovoltaic (PV) power systems and either incandescent lamps, tube lights or compact fluorescent lights (CFLs) supplied by diesel generation. The different options have been evaluated with respect to consumer costs and environmental impact. The results of the comparison show that PV generation is able to compete with diesel generation if combined with incandescent lamps, but not when tube lights or CFLs are used in the conventional supply system. It should be noted, however, that while the diesel option offer financially more attractive solutions, individual PV systems do not result in any CO2 emissions. Furthermore, PV systems normally have a higher reliability. However, since the diesel option is not only cheaper but also offers a wider range of energy services and facilitates, future connection to the national electric grid, the conclusion is that this is preferable before individual PV systems for communities similar to Urambo, if the consumers shall pay the full cost of the service.

  • 439.
    Gustafsson, Anna-Maria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Westerlund, Lars
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Heat extraction thermal response test in groundwater-filled borehole heat exchanger: Investigation of the borehole thermal resistance2011Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 36, nr 9, s. 2388-2394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In groundwater-filled borehole heat exchangers (BHEs) convective flow influences the heat transfer in the borehole. During heat extraction thermal response tests (TRTs) the effect of the changing convective flow is more dominant than during heat injection tests. Water is heaviest around 4 °C and when exceeding this temperature during the test, the convective flow is stopped and restarted in the opposite direction resulting in a higher borehole thermal resistance during that time. Just before 0 °C the convective flow is the largest resulting in a much lower borehole thermal resistance. Finally, during the freezing period phase change energy is released and material parameters change as water is transformed into ice, resulting in a slightly higher borehole resistance than at a borehole water temperature of 0 °C. The changes in borehole thermal resistance are too large for ordinary analysis methods of thermal response tests to work. Instead another method is introduced where the borehole thermal resistance is allowed to change between different time intervals. A simple 1D model of the borehole is used, which is matched to give a similar mean fluid temperature curve as the measured one while keeping the bedrock thermal conductivity constant during the whole test. This method is more time-consuming than ordinary TRT analyses but gives a good result in showing how the borehole thermal resistance changes. Also, a CFD-model with a section of a simplified borehole was used to further study the effect of convection and phase change while the temperature was decreased below freezing point. The test and the model show similar results with large variations in the borehole thermal resistance. If the knowledge of changing borehole thermal resistance was used together with a design program including the heat pump and its efficiency, a better BHE system design would be possible.

  • 440.
    Gustafsson, Anna-Maria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Westerlund, Lars
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Multi-injection rate thermal response test in groundwater filled borehole heat exchanger2010Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 35, nr 5, s. 1061-1070Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During a thermal response test (TRT) or during operation of a borehole heat exchanger (BHE) system, a temperature gradient in and around the borehole is achieved. This causes convective flow in the groundwater due to density differences. In groundwater filled BHE the convective heat flow influences the heat transport in the borehole system. The size of the influence depends on the injection rate used, which changes during the year for normal BHE systems. Multi-injection rate TRT (MIR TRT) may be used as a method to detect the convective heat influence and to examine the effect on the BHE thermal transport parameters. It was shown that MIR TRT constitutes a valuable method to detect fractured bedrock and to examine the effect of different heat injection rates. For boreholes located in solid bedrock only the borehole thermal resistance was influenced by the convective flow. An increase in heat injection rate resulted in a decrease in resistance. It was shown that the length of the collector did not affect the result. For the fractured bedrock the effective bedrock conductivity was also affected, an increase in heat injection rate resulted in a higher effective bedrock thermal conductivity.

  • 441.
    Gustafsson, Anna-Maria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Westerlund, Lars
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Simulation of the thermal borehole resistance in groundwater filled borehole heat exchanger using CFD technique2010Inngår i: International Journal of Energy and Environment, ISSN 2076-2895, E-ISSN 2076-2909, Vol. 1, nr 3, s. 399-410Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The thermal borehole resistance in a groundwater-filled borehole heat exchanger (BHE) is affected of both conductive and convective heat transfer through the borehole water. To calculate this heat transport, different models are required compared to calculation of only conductive heat transfer in a back-filled BHE. In this paper some modelling approximations for groundwater-filled, single U-pipe BHEs were investigated using a 3D CFD model. The purpose is to find approximations that enable to construct a fast, simple model including the convective heat transfer that may be used in thermal response test analyses and BHE design programs. Both total heat transfer calculations (including convective and conductive heat transport) and only conductive heat transfer calculations were performed for comparison purposes. The approximations that are investigated are the choice of boundary condition at the U-pipe wall and using a single pipe in the middle of the borehole instead of the U-pipe. For the total heat transfer case, it is shown that the choice of boundary condition hardly affects the calculated borehole thermal resistance. For the only conductive heat transfer case, the choice of boundary condition at the pipe wall gives large differences in the result. It is also shown that using an annulus model (single pipe in the middle of the borehole) results in similar heat transfer as the U-pipe model provided that the equivalent radius is chosen appropriately. This approximation can radically decrease the number of calculation cells needed.

  • 442.
    Gustafsson, Anna-Maria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Westerlund, Lars
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hellström, Göran
    CFD-modelling of natural convection in a groundwater-filled borehole heat exchanger2010Inngår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 30, nr 6-7, s. 683-691Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In design of ground-source energy systems the thermal erformance of the borehole heat exchangers is important. In Scandinavia, boreholes are usually not grouted but left with groundwater to fill the space between heat exchanger pipes and borehole wall. The common U-pipe arrangement in a groundwater-filled BHE has been studied by a three-dimensional, steady-state CFD model. The model consists of a three meter long borehole containing a single U-pipe with surrounding bedrock. A constant temperature is imposed on the U-pipe wall and the outer bedrock wall is held at a lower constant temperature. The occurring temperature gradient induces a velocity flow in the groundwater-filled borehole due to density differences. This increases the heat transfer compared to stagnant water. The numerical model agrees well with theoretical studies and laboratory experiments. The result shows that the induced natural convective heat flow significantly decreases the thermal resistance in the borehole. The density gradient in the borehole is a result of the heat transfer rate and the mean temperature level in the borehole water. Therefore in calculations of the thermal resistance in groundwater filled boreholes convective heat flow should be included and the actual injection heat transfer rate and mean borehole temperature should be considered.

  • 443.
    Gutiérrez Ballesteros, Elena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah
    Luleå University of Technology.
    Gil de Castro, Aurora
    University of Cordoba.
    Sakar, Selcuk
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Temperature and voltage distortion analysis in LED lamps2019Inngår i: CIRED conference proceedings, 2019, artikkel-id 35Konferansepaper (Fagfellevurdert)
  • 444.
    Gyllenram, Rutger
    et al.
    Kobolde & Partners.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    User friendliness: why are some beautiful models used while others are thrown in the wastepaper basket?2008Inngår i: SCANMET III: 3rd International Conference on Process Development in Iron and Steelmaking, 8-11 June 2008, Luleå, Sweden, Luleå: MEFOS , 2008, Vol. 1, s. 315-322Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Development and implementation of models in steel companies represent large values and will be even more important in the future. There are many pitfalls to step into in the process of modelling and implementation of systems. In this paper pitfalls and success factors experienced in six different projects are presented and discussed. Experiences like these are hard to earn and easily forgotten and it is concluded that this kind of knowledge management ought to be on the agenda for top management like the Corporate Technology Officer, CTO.

  • 445.
    Göktepe, Burak
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Entrained flow gasification of biomass: soot formation and flame stability2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Entrained flow gasification (EFG) is a well-proven, commercially available technology for large scale coal gasification processes, with a production of a high quality syngas (a mixture of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), methane (CH4) and other compounds). For biomass, the process is still under development and there are several hurdles that must be cleared before it can become commercial. In entrained flow gasification, solid fuel particles are milled to a size of a couple of hundred micrometers to ensure good heat and mass transfer with the surrounding hot gases, priorto be fed in a co-flow of oxidizer stream that can be either air or pure oxygen. The milled biomass particles have cohesive behavior and poor flowability, leading to serious challenges associated with consistent particle feeding and effective mixing. The pulverized fuel injector is a vital part of the gasification/combustion system and a well optimized fuel injector can help to promote the process efficiency by enhancing mixing, minimizing pollutant emission and fuel consumption. Biomass differs from coal not only in chemical composition (in terms of carbon, oxygen, volatile etc. contents) butalso in aerodynamic properties depending upon some factors, e.g. shape sphericity, aspect ratio, particle size, bulk density and particle cohesion force etc. One of the key challenges to implement biomass in entrained flow gasification is to ensure a good mixing of biomass particles with the oxidizer stream. A common concept is to impart swirling motion into the oxidizer stream, forming a recirculated hot gas flow that can participate in the gasification. The dispersion behavior of biomass particles in turbulentisothermal swirling flows has therefore been studied by using a two-phase particle image velocimetry technique. This technique provides simultaneous measurements of continuous (air) and disperse phase (pulverized pine particles) velocities. The results show that the addition of pulverized pine particles (with a size range of 112-160 μm) into turbulent air flow significantly affect the dispersion rate and velocity fields of thesuspending air flow in the burner near field, inducing a “blockage effect” where the air velocity is reduced along the jet core corresponding to a region of high particle concentration. It was also found that imparting swirling motion to the co-annular jet flow increased the particle dispersion due to strong centrifugal effects induced by the swirling motion. The entrained flow gasifier is operated at high temperatures to maintain high conversionand high cold gas efficiency, resulting in low tar yields, high oxygen demand and a viscous slag flow. High operating temperatures also favors soot formation that can be detrimental to the operation of the gasifier, e.g. clogging of flow passages, fouling on system components and reduced efficiency of gasification. A novel soot reduction method on the basis of forced dispersion of fuel particles has therefore been applied toa laboratory scaled entrained flow reactor. Pulverized pine particles with a size of 63- 112 μm were gasified in a sub-stoichiometric methane-air flame stabilized on a flat burner. Soot formation was measured along the reactor height in terms of volume fraction by a two-color laser extinction method. The results show that particle dispersion and inter-particle distance were enhanced by varying the flow velocity ratio between the particle carrier gas and the premixed flame. The soot volume fraction was found todecrease towards an asymptotic value with increasing inter-particle distance.There are other techniques to control particle dispersion and promote mixing, e.g. acoustic forcing or a synthetic jet flow. Both techniques induce a periodic motion to the gas phase flow that influences the motion of solid fuel particles. A synthetic jet actuator was used in both isothermal and reactive flows in a laboratory scale entrained flow reactor. It was found that the synthetic jet actuator formed local flows of dilute and dense gas particle suspensions via a convection effect induced by large scale flow structures. It was also shown that the synthetic jet actuator provided controlled particle dispersionin isothermal flows with respect to forcing amplitudes. The resulting flow field imposed significant effects on the amount of soot formed during gasification of pulverized pine particles.Acoustic forcing was applied to a 150 kW wood powder burner to excite one of thenatural system instabilities during combustion of wood powder particles. The effect of the instabilities on the flame shape and NOx formation were investigated at differentair/fuel ratios. The powder flame gave a quick response to external flow perturbations at 17 Hz showing irregular wobbling and increased NOx emission in the presence of acoustic excitation. Based on the experiences gained from the experiments, dispersion characteristics of particle-laden flow are of utmost importance to reliably predict and optimize pollutant emission. Controlled particle dispersion can be simply achieved by external forcing ofthe gas flow by a synthetic jet actuator without any need of a source of external fluid or time-consuming, expensive burner modifications.

  • 446.
    Göktepe, Burak
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Interaction of sound waves with a swirl stabilized wood powder flame and their effects on flame characteristics2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Swirling flows have been widely used for many years in engineering applications such as; chemical and mechanical mixing devices, separation units, spray drying technologies, turbo machinery and combustion systems. In practical combustion applications, swirl motion has been adopted to the incoming reactant flows in order to enhance the mixing of fuel and oxidizer and to improve flame stabilization and establishment, especially in regions of relatively low velocities, by recirculating hot product gas to the incoming reactants. At critical operating conditions the recirculation zone exhibit high sensitivity to flow disturbances leading to hydrodynamic instabilities. During combustion, these instabilities can interact with flame structures by modulating the rate of heat release, equivalence ratio, flame surface etc. As a result of these interactions, combustion instabilities can form in the systems. At initial state, combustion instabilities can stay unnoticed due to their relatively small amplitudes, but the amplitudes of the instabilities can increase when they couple with acoustical characteristics of any particular system elements. As a result, combustion systems can suffer from high amplitude noise, vibrations, flame flashback, local flame quenching, and even severe damages in system structures. This thesis provides insights into the interaction of acoustic waves with a swirl stabilized wood powder flame and its effects on flame structures. A high speed photography technique has been applied to wood powder flame under external forcing of the secondary air flow pattern to record spontaneous emission of radiant energy from the flame. Simultaneously, dynamic pressure signals were acquired with a data acquisition board in order to relate pressure data with radiant energy which has been assumed to be representative of heat release. In order to investigate the influence of the interactions on combustion, the resulting data were complemented with gas sampling measurements. From digital still images taken without external forcing, the wood powder flame was observed to expand to occupy the entire combustion chamber. In addition, the flame shape and size appears to be unchanged under a wide range of forcing frequencies, with one exception at a particular low frequency for which a resonant behaviour was observed. The critical frequency was 17 Hz independent of amplitude of the forcing frequency and at this forcing frequency dramatic changes in flame size and shape was observed. Instantaneous and phase averaged images have revealed the presence of large scale vortical structures that closely interacted with the flame surface. A fast Fourier transform of the point wise optical signal also shows that the flame is susceptible to instabilities at the acoustical forcing of 17 Hz. The existence of thermo-acoustically induced combustion instability has been investigated by a Rayleigh criterion which states that the amplitude of a sound wave will be amplified when heat is added less than 90 degrees out of phase with its pressure. In this study, the heat release extracted from high speed images recorded at 17 Hz is approximately 40 degrees out of phase with the pressure data which confirms the thermo-acoustic nature of the instability. Finally, from gas sampling measurements it was concluded that the acoustic oscillations at 17 Hz have increased the NOx emission level to around twice the level without forcing.

  • 447. Göktepe, Burak
    et al.
    Gebart, Rikard
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Fernandes, Edgar
    Instituto Superior Técnico, Dpartment of Mechanical Engineering/Center IN.
    Leitão, Noel
    Instituto Superior Técnico, Dpartment of Mechanical Engineering/Center IN.
    Leitão, Ivo
    Instituto Superior Técnico, Dpartment of Mechanical Engineering/Center IN.
    Merícia, Janaína Gomes de
    Instituto Superior Técnico, Dpartment of Mechanical Engineering/Center IN.
    Simultaneous pressure and heat release measurements in a 150kW wood powder burner2010Konferansepaper (Annet vitenskapelig)
  • 448. Göktepe, Burak
    et al.
    Gebart, Rikard
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Leitao, Noel
    Instituto Superior Técnico, Dpartment of Mechanical Engineering/Center IN.
    Fernandesc, Edgar
    Instituto Superior Técnico, Dpartment of Mechanical Engineering/Center IN.
    Visualization of the reactive swirling flows in a 150 KW wood powder burner2010Konferansepaper (Annet vitenskapelig)
  • 449.
    Göktepe, Burak
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hazim, Ammar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Gebart, Rikard
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lundström, Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Cold flow experiments in an entrained flow gasification reactor with a swirl-stabilized pulverized biofuel burner2016Inngår i: International Journal of Multiphase Flow, ISSN 0301-9322, E-ISSN 1879-3533, Vol. 85, s. 267-277Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Short particle residence time in entrained flow gasifiers demands the use of pulverized fuel particles to promote mass and heat transfer, resulting high fuel conversion rate. The pulverized biomass particles have a wide range of aspect ratios which can exhibit different dispersion behavior than that of spherical particles in hot product gas flows. This results in spatial and temporal variations in temperature distribution, the composition and the concentration of syngas and soot yield. One way to control the particle dispersion is to impart a swirling motion to the carrier gas phase. This paper investigates the dispersion behavior of biomass fuel particles in swirling flows. A two-phase particle image velocimetry technique was applied to simultaneously measure particle and gas phase velocities in turbulent isothermal flows. Post-processed PIV images showed that a poly-dispersed behavior of biomass particles with a range of particle size of 112-160 μm imposed a significant impact on the air flow pattern, causing air flow decelerated in a region of high particle concentration. Moreover, the velocity field, obtained from individually tracked biomass particles showed that the swirling motion of the carrier air flow gives arise a rapid spreading of the particles

  • 450.
    Göktepe, Burak
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gebart, Rikard
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Does distance among biomass particles affect soot formation in an entrained flow gasification process?2016Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 141, nr 1, s. 99-105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Soot creates technical challenges in entrained flow biomass gasification processes, e.g. clogging of flow passages, fouling on system components and reduced efficiency of gasification. This paper demonstrates a novel soot reduction method in a laboratory-scale entrained flow reactor by forced dispersion of biomass particles. Gasification of small biomass particles was done in a flat flame burner where a steady stream of biomass was sent. The flat flame burner was operated with a premixed sub-stoichiometric methane–air flame to simulate the conditions in an entrained flow gasifier. The dispersion of biomass particles was enhanced by varying the flow velocity ratio between particle carrier gas and the premixed flame. Primary soot particles evolved with the distance from the burner exit and the soot volume fraction was found to have a peak at a certain location. Enhanced particle separation diminished the peaks in the soot volume fraction by 35–56% depending on the particle feeding rates. The soot volume fraction was found to decrease towards an asymptotic value with increasing inter-particle distance.

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