Stein Tore Johansen
SINTEF, Process Technology, Faculty Member
Mathematical modeling has for a long time been of crucial importance for the understanding and prediction of phenomena in the heavy industries. Previously, the main source of knowledge was practical experience with operations and use of... more
Mathematical modeling has for a long time been of crucial importance for the understanding and prediction of phenomena in the heavy industries. Previously, the main source of knowledge was practical experience with operations and use of simplified, but fundamental understanding of the chemistry and materials that was involved in the processes. Lately, during the last three decades, the development of the digital computers has offered new tools to the process analyst. Today, Computational Fluid Dynamics (CFD) software is, at least in the larger companies, used on a daily basis in order to support new developments and troubleshoot operational problems. The cornerstone in CFD software is the mixture of physical models and the numerical technologies that are used for solutions of the governing transport equations. As the number crunching capabilities of the computers expand, the limitations in penetrating the inner depth of the processes seems to be less attributed to the computer power...
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Assuring transport and separation of oil and water crude emulsions is of significant importance to the oil and gas industries. The crude oil, due to its profuse chemical composition, has complex dispersion and emulsion flow behavior with... more
Assuring transport and separation of oil and water crude emulsions is of significant importance to the oil and gas industries. The crude oil, due to its profuse chemical composition, has complex dispersion and emulsion flow behavior with water. As a result, of the interface chemistry, the bubbles and droplets may separate easily, or not separate at all, impacting flow regime, water holdup, pressure drop and separation efficiency during pipe transport. Using a recently developed new stirred tank characterization technique for emulsion stability droplet relaxation parameters can be studied. Multiple model oils and crude oils were characterized by this technique. This work discusses development of a pragmatic modeling method that can validate the experimental measurements. A time averaged velocity profile in a stirred tank is used to obtain a 1-D flux flow profile in the vertical direction. This 1-D flux profile is used as a simplified flow equation and scalar equations for droplet size and dispersed phase fraction is used for modeling the emulsion stability and relaxation. This method can help in fast simulation of emulsion stability that involves long time scales of coalesence and breakage evolution for crude oil and water.publishedVersio
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A distinct characteristic of reservoir fluids in different Brazilian pre-salt fields is the high Gas-Oil- Ratio (GOR) and high content of CO2 in the associated gas. In particular, the presence of CO2 in significant amounts is known to... more
A distinct characteristic of reservoir fluids in different Brazilian pre-salt fields is the high Gas-Oil- Ratio (GOR) and high content of CO2 in the associated gas. In particular, the presence of CO2 in significant amounts is known to have a strong influence on the thermophysical properties and phase equilibria of the oil mixtures. Due to the strategy of re-injection of CO2-rich streams for EOR purposes, these aspects can be even more pronounced in the production fluids in future scenarios. In the present work, a parametric study is performed to investigate the influence of both CO2 molar content and GOR, in a controlled manner, on the simulations of a pre-salt field configuration for various operating conditions. PVT look-up tables were used with a commercial multiphase flow simulator. First, the thermodynamic modelling of a 20% molar CO2 pre-salt oil was performed, along with well characterized CO2-live oil mixtures taken from the literature, in order to generate PVT look-up tables. They were used to successfully reproduce field data and assess the validity of multiphase flow simulation results from a commercial software. For the CO2-rich live oil mixtures from the literature, a parametric study was performed in which the CO2 molar content ranged from 20% to 50% with 300-600 Sm3/Sm3 of GOR. Simulation results of temperature, total pressure drop, gas volume fraction and gas- liquid density ratio are presented and compared.
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Research Interests: Pragmatism and Workflow
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Air is supplied through a porous plug placed in the center axis of a cylindrical perspex-water model of a ladle. A laser-doppler system is employed to measure radial and axial mean and fluctuating velocities. Also velocities in the... more
Air is supplied through a porous plug placed in the center axis of a cylindrical perspex-water model of a ladle. A laser-doppler system is employed to measure radial and axial mean and fluctuating velocities. Also velocities in the two-phase bubbly region ..
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In a Europe that is undergoing digital transformation, the COGNITWIN project is contributing to accelerate the transformation and introduce Industry 4.0 to the European process industries. The opportunities here can be illustrated by the... more
In a Europe that is undergoing digital transformation, the COGNITWIN project is contributing to accelerate the transformation and introduce Industry 4.0 to the European process industries. The opportunities here can be illustrated by the SPIRE 2050 Vision document (https://www.spire2030.eu/sites/default/files/users/user85/Vision_Document_V6_Pages_Online_0.pdf), which states that “Digitalisation of process industries has a tremendous potential to dramatically accelerate change in resource management, process control and in the design and the deployment of disruptive new business models.” The process industries are characterized with harsh environments where sensors are either costly, not available, or may be subject to costly maintenance. The development of digital twins that can exploit the combinations of data-based and physics-based models is often found to be a preferred path to robust digital twins that can help cutting costs and reduce energy consumption. In this article, we pr...
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As part of the development of the LedaFlow multiphase simulation tool, experiments have been performed to investigate detailed flux- and velocity profiles in two-phase flows with Nitrogen and Naphtha. The experiments have been recorded in... more
As part of the development of the LedaFlow multiphase simulation tool, experiments have been performed to investigate detailed flux- and velocity profiles in two-phase flows with Nitrogen and Naphtha. The experiments have been recorded in an 8 inch diameter pipe with 0.5° inclination at 20 and 90 bar pressure. Results and implications from these measurements are discussed. Next, a detailed model for droplet entrainment is presented. The experimental data is analysed based on the proposed model framework and the model is calibrated using the available measurements. The subsequent results are discussed.
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ACKNOWLEDGEMENT. A POP-SEP funding from SINTEF has been used for the 1D particle-reactor model software development. The multi-scale model development has been carried out as a part of the DemoCLOCK project, which is an EU FP7 funded... more
ACKNOWLEDGEMENT. A POP-SEP funding from SINTEF has been used for the 1D particle-reactor model software development. The multi-scale model development has been carried out as a part of the DemoCLOCK project, which is an EU FP7 funded project under the ENERGY.2010.6.1-1 programme.
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The Si-Mn alloy process production in submerged arc furnaces (SAF) is investigated. The aim of the studies currently in progress is an enhancement of the knowledge about the key reactions and the mass transport phenomenon related to the... more
The Si-Mn alloy process production in submerged arc furnaces (SAF) is investigated. The aim of the studies currently in progress is an enhancement of the knowledge about the key reactions and the mass transport phenomenon related to the metal production. Some small scale experiments on raw materials and bigger pilot scale experiments are done to understand local kinetic and its extension to real condition production furnaces. As it is impossible to observe what is happening in the core of the furnace during operation, excavation of the pilot scale furnace are realised after operations. Based on bibliographical description of similar processes, observations and species analyses after excavation, a numerical simulation is currently in development to test the hypothesis formulated about the internal behaviour of the furnace. As it is difficult to model the complex entire furnace, the work presented here is focusing on what are the phenomenas inside the coke bed, in the dripping zone where the slags flow around the carbon particles before reaching the bottom of the furnace. The thrickling of the slags across the coke bed can be evaluated by a simulation of the droplets finding their path by gravity through the packing of carbon particles. This study has to be very local in space and time, but can give some useful informations such as velocities and drag force. At a larger scale (ie furnace scale), the coke bed particles are modelled by a granular phase in an eulerian-eulerian representation where the slag phase flow interact in the same way as in the local study. The slag is found to flow across the coke bed under the form of droplets of a maximum diameter of 10mm. The apparent velocity of the fluid is about 0,12 m/s. However the residence time of the droplets is longer due to the liquid trapped along the coke bed
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Discrete phase method (DPM) model was used to analyse rotary drum systems for segregation behavior. DPM simulations were performed for comparison with a dynamic segregation experimental measurement from the literature. This included... more
Discrete phase method (DPM) model was used to analyse rotary drum systems for segregation behavior. DPM simulations were performed for comparison with a dynamic segregation experimental measurement from the literature. This included dynamic segregation and time-averaged particle velocity field, which were validated with experimental data. In addition, a direct DPM and parcel scaled DPM simulation study was performed to analyse the effect of drum and particle parcel size scaling. The segregation dynamics was evaluated using the Lacey mixing index. This work shows segregation dynamics decreases with increasing drum size while keeping the same particle size. It further shows that for a given drum size the segregation dynamics deviate after a certain particle parcel scaling limit. The parcel scaling limit also increases with increasing drum size.
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Research Interests: Interception and settling
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The mathematical modelling of species transport in the turbulent boundary layer of fluids that precipitate on the wall, is an important topic at the heart of one of the biggest challenges in efficient energy utilization in all process... more
The mathematical modelling of species transport in the turbulent boundary layer of fluids that precipitate on the wall, is an important topic at the heart of one of the biggest challenges in efficient energy utilization in all process industries; namely the fouling of heat exchangers. A major contributor to the complexity of the problem is the multi-length-scale nature of the governing phenomena. That is, transport mechanisms dominating at the nano-scale may be responsible for the macroscopic performance of the industrial process. This paper addresses some of the challenges that need to be met in modelling the boundary conditions, i.e. the atomic/molecular-scale conditions, for the species-specific mass conservation equations, at the wall, for single-phase, multi-component fluids that precipitate at the wall.
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Research Interests: Sociology and Pragmatism
Authors : Balram Panjwani, Bernd Wittgens, Jan Erik Olsen, Stein Tore Johansen Abstract : The Norwegian ferroalloy industry is a world leader in sustainable production of ferrosilicon, silicon and manganese alloys with the lowest global... more
Authors : Balram Panjwani, Bernd Wittgens, Jan Erik Olsen, Stein Tore Johansen Abstract : The Norwegian ferroalloy industry is a world leader in sustainable production of ferrosilicon, silicon and manganese alloys with the lowest global specific energy consumption. One of the byproducts during the metal reduction process is energy rich off-gas and usually this energy is not harnessed. A novel concept for sustainable energy recovery from ferroalloy off-gas is discussed. The concept is founded on the idea of introducing a combustion chamber in the off-gas section in which energy rich off-gas mainly consisting of CO will be combusted. This will provide an additional degree of freedom for optimizing energy recovery. A well-controlled and high off-gas temperature will assure a significant increase in energy recovery and reduction of emissions to the atmosphere. Design and operation of the combustion chamber depend on many parameters, including the total power capacity of the combustion c...
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The service life of aluminium reduction cells is limited by cathode wear. A typical wear pattern has been reported as a single or double “W” profile. The uneven cathode wear appears to be controlled by multiple mechanisms such as... more
The service life of aluminium reduction cells is limited by cathode wear. A typical wear pattern has been reported as a single or double “W” profile. The uneven cathode wear appears to be controlled by multiple mechanisms such as non-uniform current distribution and carbide dissolution. According to our analyses, formation of aluminium carbide that dissolves into a bath film located on the cathode surface is the dominating mechanism. A dynamic model was developed in order to calculate the local carbide formation as well as cathode wear rate. The present model utilizes a simplified geometry where the metal flow, which is driven by the Lorentz force, results in shear stress and motion of the bath film. The simulations demonstrate how the local current distribution and the mass transfer of aluminium carbide from the cathode surface and into the bath film result in uneven cathode wear profiles.
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In this study we focus on a generic method to model the generation of droplets from a non-resolved simulation of free surface flow. The application is entrainment of droplets from the large-scale interface of waves interacting with a wind... more
In this study we focus on a generic method to model the generation of droplets from a non-resolved simulation of free surface flow. The application is entrainment of droplets from the large-scale interface of waves interacting with a wind field. At first, the droplets generation rate will be calculated based on the local shear stress and other interface properties. Then, a special method is applied to detach liquid droplets from the continuous phase such that the total mass and momentum are conserved. Droplets trajectories will be computed using Lagrangian tracking method. Droplets that collide with the large-scale interface will again become continuous water and are removed from the computation. The interaction between droplets and surrounding gas will be accounted by adding a source term in momentum equations. In order to achieve a stable result, the source term will be handled implicitly. The model suggestions are explored and verified through simulations. The prospects of this modelling approach is discussed
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In this paper we present our strategy and implementation of a datacentric modelling framework (SOFT, SINTEF Open Framework and Tools) with focus on information interchange in throughprocess and multiscale applications. SOFT needs to... more
In this paper we present our strategy and implementation of a datacentric modelling framework (SOFT, SINTEF Open Framework and Tools) with focus on information interchange in throughprocess and multiscale applications. SOFT needs to accommodate for a inhomogeneous set of in-house open source and proprietary simulators, often written in different programming languages, and storing data in different formats. The complexity and diversity of such a system requires that we have formal schemas and structures of metadata that allow for information interpretation regardless of the original storage formats, which application produced the data, and which application processes the data. We propose a standard for data exchange, separately describing metadata specific to different knowledge domains. SOFT, via a mechanism of plugins, offers the possibility to utilize different tools for storage of such data and metadata. Further, SOFT facilitates scientific software development by clear separation of numerical routines and platform-dependent input, output, and analysis routines. Automated testing and simulation data analysis are also achieved in SOFT via external plugins and interfaces to scripted languages such as Python and Javascript. The framework has been developed and tested within such flow modelling projects as LedaFlow, NanoSim and SimcoFlo
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In petroleum drilling, aqueous Polyanionic Cellulose solutions (PAC) are often used as a drilling fluid model system in experimental laboratory studies to investigate cuttings transport. Cuttings transport refers to the transportation of... more
In petroleum drilling, aqueous Polyanionic Cellulose solutions (PAC) are often used as a drilling fluid model system in experimental laboratory studies to investigate cuttings transport. Cuttings transport refers to the transportation of drilled-off solids out of the wellbore. In these studies, PAC solutions are typically assumed to behave purely viscous, i.e. they do not show time-dependent/thixotropic and/or viscoelastic properties. In this study, a rheological characterization of PAC has been performed in combination with an evaluation of time scales characterizing the fluid to verify the conventional assumption of a purely-viscous fluid. It is found that PAC solutions are generally not purely viscous: They feature viscoelastic behavior on time scales of the order of 0.01 to 1 s, such as normal stress differences, as well as thixotropic behavior on larger time scales of the order of 10 to 1000 s because of their polymeric microstructure. If simplified to a purely viscous fluid, t...
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ACKNOWLEDGEMENTS.The financial support to the Leda Project, the long-time contributions from the Leda Technical Advisory Committee, as well as permission to publish, by Total, ConocoPhillips, and SINTEF are all gratefully acknowledged.... more
ACKNOWLEDGEMENTS.The financial support to the Leda Project, the long-time contributions from the Leda Technical Advisory Committee, as well as permission to publish, by Total, ConocoPhillips, and SINTEF are all gratefully acknowledged. Our colleagues Ernst Meese, and Runar Holdahl (SINTEF), Wouter Dijkhuizen and Dadan Darmana (Kongsberg Oil & Gas Technologies), Harald Laux (OSRAM Opto Semiconductors GmbH, Regensburg), and Alain Line (INSA, Toulouse) are acknowledged for their contributions to the development.
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Simulation of multiphase flows is generally treated by various classes of Eulerian methods, Lagrangian methods, and various combinations of these. In the SIMCOFLOW initiative, we have set out to develop a framework for simulation of... more
Simulation of multiphase flows is generally treated by various classes of Eulerian methods, Lagrangian methods, and various combinations of these. In the SIMCOFLOW initiative, we have set out to develop a framework for simulation of multi-material flows, using a Eulerian description. A fundamental part is the application of Cartesian grids with cut cells, and with a staggered representation of the grid for velocities and scalars. The model equations are derived based on formal volume and ensemble averaging (Quintard and Whitaker, 1995), (Gray and Lee, 1977) and (Cushman, 1982). Solid walls or moving solid materials are treated in the same manner as any flowing material (fluid, deforming material). The interface is characterized by a level set or by a 3D surface. In grid cells that are cut by a large-scale interface, the stress acting at the cut surface can be computed based on the level set or volume fractions. The exchange of mass, energy, and momentum between continuous fluids (note: walls are also considered a continuous fluid) can be estimated using wall functions in the case of coarse grids. The methods applied to the flow in a general geometry are closely related to the FAVOR method (Hirt and Sicilian, 1985) and the LS-STAG method (Cheny and Botella, 2010). In this paper, we discuss the derivation of the equations and the numerical solution strategy needed to handle such complex physics within the framework of finite volume methods. We further discuss briefly the ongoing developments such as adaptive gridding and the computational framework. The results of this work will end up as open source software
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In petroleum drilling, cuttings transport problems, i.e. an accumulation of drilled of solids in the wellbore, are a major contributor to well downtime and have therefore been extensively researched over the years, both experimentally and... more
In petroleum drilling, cuttings transport problems, i.e. an accumulation of drilled of solids in the wellbore, are a major contributor to well downtime and have therefore been extensively researched over the years, both experimentally and through simulation. In recent years, Computational Fluid Dynamics (CFD) has been used intensively due to increasing available computational power. Here, the problem of cuttings transport is typically investigated as a laminar/turbulent, potentially non-Newtonian (purely shear-thinning) multiphase problem. Typically, an Eulerian-Eulerian two-fluid model concept is utilized, where the particle phase is treated as a second continuous phase. Optionally, a granular flow model, based on the Kinetic Theory of Granular Flow (KTGF), may be used to account for the dense granular flow properties of cuttings forming a sediment bed. One issue of the state of the art CFD approach as described above is the proper resolution of the bed interface, as this may not be accurately resolved in an industrial-relevant CFD simulation. In this paper, an alternative approach is taken based on modeling concepts used in environmental sediment transport research (rivers, deserts). Instead of including the sediment bed in the computational domain, the latter is limited to the part of the domain filled with the particle-loaded continuous fluid phase. Consequently, the bed interface becomes a deformable domain boundary, which is updated based on the solution of an additional scalar transport equation for the bed height, which is based on the so-called Exner equation (Exner, 1925), a mass conservation equation accounting for convection, and additionally deposition and erosion in the bed load layer. These convective fluxes are modeled with closures relating these fluxes to flow quantities. As a first step, a 2D model was implemented in ANSYS Fluent R17.2 using Fluent’s dynamic mesh capabilities and User-Defined Function (UDF) interfaces. The model accounts for local bed slope, hindered settling, and non-Newtonian, shear-thinning viscosity of the fluid phase as well as turbulence. Model results are benchmarked with experimental data for five different operating points. Most probably due to the utilized unsteady Reynolds-Averaging framework (URANS), the model is not capable of predicting flow-induced dunes; however, it does predict bed deformation as a consequence of for instance non-equilibrium boundary conditions. Other model issues such as e.g. non-Newtonian formulations of the closures are identified and discussed
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The project Advanced Wellbore transport Modelling (AdWell) with its sponsor, the Research Council of Norway and its partners Statoil, ENGIE E&P Norge AS, IRIS, UiS, NTNU and SINTEF are gratefully acknowledged for funding and supporting... more
The project Advanced Wellbore transport Modelling (AdWell) with its sponsor, the Research Council of Norway and its partners Statoil, ENGIE E&P Norge AS, IRIS, UiS, NTNU and SINTEF are gratefully acknowledged for funding and supporting this work.
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The prediction of drop sizes in dispersions is important in a number of industrial applications. Although many advances have been achieved in the understanding of the factors influencing drop size distributions obtained in high shear... more
The prediction of drop sizes in dispersions is important in a number of industrial applications. Although many advances have been achieved in the understanding of the factors influencing drop size distributions obtained in high shear systems, as well as size evolution throughout pipe flow and equipment, there are still many open questions that remain to be addressed. Here, the governing breakage mechanisms under different conditions will be reviewed, including various fluid systems and experimental apparatuses. Furthermore, different models that have been proposed in the literature will be outlined, including mechanistic models and drop size evolution approaches. Finally, a practical approach to study dynamic emulsion stability characterization will be presented.
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In oil and gas drilling, cuttings transport related problems are a major contributor to well downtime and costs. As a result, solutions to these problems have been extensively researched over the years, both experimentally and through... more
In oil and gas drilling, cuttings transport related problems are a major contributor to well downtime and costs. As a result, solutions to these problems have been extensively researched over the years, both experimentally and through simulation. Numerous review articles exist, summarizing not only the research history but also the qualitative effect of individual case parameters such as e.g. pump flow rate, pipe rotation, rate of penetration on cuttings transport. However, comparing different studies is challenging, as there is no common reference basis defined in the form of typical and representative set of case parameters. In order to develop relevant and accurate cutting transport models, it is critical that both experiments and models are targeting flow cases, which are relevant for respective drilling operations. By developing a clear understanding of the industrial parameter space, as well as establishing critical benchmarks, the development of models and corresponding labor...
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Multiphase flows in oil- and gas pipelines involve a variety of different flow regimes. The different flow regimes are determined by the geometric arrangement of oil, gas and water inside the pipe, and evolve in a dynamic manner along a... more
Multiphase flows in oil- and gas pipelines involve a variety of different flow regimes. The different flow regimes are determined by the geometric arrangement of oil, gas and water inside the pipe, and evolve in a dynamic manner along a flowline, from bottom hole to receiving facilities. Along the path of the flow, the geometric fluid arrangements (or flow patterns), which develop dynamically, are often outside what is properly accounted for in existing 1D flow models. In such cases, more detailed multidimensional models are needed. As the industry is facing tighter operating margins and stricter regulatory frameworks, more accurate and predictive tools are needed. It is realized that CFD (Computational Fluid Dynamics) type models cannot replace 1D models in most cases, but will be an extremely valuable addition to the toolbox in cases where the 1D models may be insufficient. In the present paper a CFD method will be presented which enables such generic simulations. In this model, t...
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There are several challenges associated to the pre-salt development at the Santos basin, such as long distances from the coast, low temperature reservoirs, high pressures, high water depth, among others. Additional aspects contributing to... more
There are several challenges associated to the pre-salt development at the Santos basin, such as long distances from the coast, low temperature reservoirs, high pressures, high water depth, among others. Additional aspects contributing to the complex production scenario are related to fluid characteristics and flow assurance. In particular, the high CO2 content in the dissolved gas is an important characteristic that should be also analyzed, because CO2 is not only a heavy component, when compared to lighter components present in the gas phase, but has also a high Joule-Thomson coefficient. This affects pressure drop and specially the mixture cooling behavior during decompression. The cooling effect is expected to be strong at high production rates. Thus, the objective of the present work is to evaluate these effects under present and future production scenarios, taking into account increasing CO2 contents due to re-injection strategies. Two different field configurations were inves...