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Modeling and simulation of circulating fluidized bed reactors applied to a carbonation/calcination loop

Particuology 2014年第4期12卷 116-128页

作者： Rafael A.Sánchez hugo a.jakobsen Department of Chemical Engineering Norwegian University of Science and Technology7034 TrondheimNorway

A fluid dynamic model for a gas-solid circulating fluidized bed （CFB） designed using two coupled riser reactors is developed and implemented numerically with code programmed in Matlab. The fluid dynamic model contains heat and species mass balances to calculate temperatures and compositions for a carbonation/calcination loop process. Because of the high computational costs required to resolve the three-dimensional phenomena, a model representing a trade-offbetween computational time requirements and accuracy is developed. For dynamic processes with a solid flux between the two reactor units that depends on the fluid dynamics of both risers, a dynamic one-dimensional two-fluid model is sufficient. A two-fluid model using the constant particle viscosity closure for the stress term is used for the solid phase, and an algebraic turbulence model is applied to the gas phase. The numerical model implementa- tion is based on the finite volume method with a staggered grid scheme. The exchange of solids between the reactor units constituting the circulating fluidized bed （solid flux） is implemented through additional mass source/sink terms in the continuity equations of the two phases, For model validation, a relevant experimental analysis provided in the literature is reproduced by the numerical simulations, The numerical analysis indicates that sufficient heat integration between the two reactor units is important for the performance of the circulating fluidized bed system, The two-fluid model performs fairly well for this chemical process operated in a CFB designed as two coupled riser reactors. Further analysis and optimization of the solution algorithms and the reactor coupling strategy is warranted.

关键词： Chemical reactors Fluidization Mathematical modeling Multiphase flow Simulation

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Multiphysic Two-Phase Flow Lattice Boltzmann:Droplets with Realistic Representation of the Interface

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Communications in Computational Physics 2011年第5期9卷 1414-1430页

作者： Pablo M.Dupuy María Fernandino hugo a.jakobsen Hallvard F.Svendsen Department of Chemical Engineering Norwegian University of Science and TechnologyN-7491 TrondheimNorway Department of Energy and Process Engineering Norwegian University of Science and TechnologyN-7491 TrondheimNorway CSIRO-Mathematics Informatics and StatisticsMelbourneAustralia.(Current affiliation)

Free energy lattice Boltzmann methods are well suited for the simulation of two phase flow *** model for the interface is based on well understood physical *** most cases a numerical interface is used instead of the physical one because of lattice resolution *** this paper we present a framework where we can both follow the droplet behavior in a coarse scale and solve the interface in a fine scale *** apply the method for the simulation of a droplet using an interface to diameter size ratio of 1 to *** a second simulation,a small droplet coalesces with a 42 times larger droplet producing on it only a small capillary wave that propagates and dissipates.

关键词： Two-phase flow diffuse interface model multi-scale real interface

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Multi-fluid modeling of density segregation in a dense binary fluidized bed

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Particuology 2012年第1期10卷 62-71页

作者： Zhongxi Chao Yuefa Wang Jana P. jakobsen Maria Fernandino hugo A. jakobsen Department of Chemical Engineering NTNU Trondheim 7491 Norway SINTEF Energy Trondheim 7491 Norway Department of Energy and Process Engineering NTNU Trondheim 7491 Norway

This paper presents simulation results of the density segregation in a dense binary gas fluidized bed using a multi-fluid model from Chao et al. （2011）, The segregation behavior of two types of particles with approximately same particle diameters and different particle densities was studied and validated using the experimental data from Formisani et al, （2008）. Some detailed information regarding the gas, particle velocity profiles, the distributions of the particle volume fractions and the flotsam-to-total par- ticle volume fraction ratios is presented. The simulation results show that the simulated axial average flotsam-to-total particle volume fraction ratio distribution agrees reasonably with the experimental data of Formisani et al. （2008）. The binary particle velocities are closely coupled though the segregation exists, The segregation behavior and the particle velocity profiles are superficial gas velocity dependent. The number and distribution of particle velocity vortices change dramatically with superficial gas velocity： at a comparatively low superficial gas velocity, the particles mainly segregate axially, and at a comparatively high superficial gas velocity, the particles segregate both axially and radially.

关键词： Fluidized bedBinary flowDensity segregationMulti-fluid modelGranular flow

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Full scale amendment of a contaminated wood impregnation site with iron water treatment residues

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Frontiers of Environmental Science & Engineering 2016年第4期10卷 169-178页

作者： Sanne Skov NIELSEN Peter KJELDSEN Rasmus jakobsen Orbicon Ringstedvej 20 DK-4000 Roskilde Denmark Department of Environmental Engineering Technical University of Denmark Miljovej 113 DK-2800 Kgs. Lyngby Denmark Geological Survey of Denmark and Greenland Geological Survey of Denmark and Greenland Oster Voldgade 10 DK-1350 Copenhagen K Denmark

Iron water treatment residues （Fe-WTR） are a free by-product of the treatment of drinking water with high concentration of iron oxides and potential for arsenic sorption. This paper aims at applying Fe- WTR to a contaminated site, measuring the reduction in contaminant leaching, and discussing the design of delivery and mixing strategy for soil stabilization at field scale and present a cost-effective method of soil mixing by connnon contractor machinery. Soil contaminated by As, Cr, and Cu at an abandoned wood impregnation site was amended with 0.22% （dw） Fe-WTR. To evaluate the full scale amendment a 100 mtest site and a control site （without amendment） were monitored for 14 months. Also soil analysis of Fe to evaluate the degree of soil and Fe-WTR mixing was done. Stabilization with Fe-WTR had a significant effect on leachable contaminants, reducing pore water As by 93%, Cu by 91% and Cr by 95% in the upper samplers. Dosage and mixing of Fe-WTR in the soil proved to be difficult in the deeper part of the field, and Pire water concentrations of arsenic was generally *** water logged conditions no increase in dissolved iron or arsenic was observed in the amended soil. Our field scale amendment of contaminated soil was overall successful in decreasing leaching of As, Cr and Cu. With minor improvements in the mixing and delivery strategy, this stabilization method is suggested for use in cases, where leaching ofCu, Cr and As constitutes a risk for groundwater and freshwater.

关键词： Field experiment Iron oxide Arsenic Stabilization Wood preservation sites

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Field scale interaction and nutrient exchange between surface water and shallow groundwater in the Baiyang Lake region,North China Plain

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Journal of Environmental Sciences 2016年第7期28卷 60-75页

作者： Bentje Brauns Poul L.Bjerg Xianfang Song Rasmus jakobsen Department of Environmental Engineering Technical University of Denmark State Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences Sino-Danish Center for Education and Research Geological Survey of Denmark and Greenland

Fertilizer input for agricultural food production, as well as the discharge of domestic and industrial water pollutants, increases pressures on locally scarce and vulnerable water resources in the North China Plain. In order to：（a） understand pollutant exchange between surface water and groundwater,（b） quantify nutrient loadings, and（c） identify major nutrient removal pathways by using qualitative and quantitative methods, including the geochemical model PHREEQC） a one-year study at a wheat（Triticum aestivum L.） and maize（Zea mays L.） double cropping system in the Baiyang Lake area in Hebei Province, China, was undertaken. The study showed a high influence of low-quality surface water on the shallow aquifer. Major inflowing pollutants into the aquifer were ammonium and nitrate via inflow from the adjacent Fu River（up to 29.8 mg/L NH4-N and 6.8 mg/L NO3-N）, as well as nitrate via vertical transport from the field surface（up to 134.8 mg/L NO3-N in soil water）. Results from a conceptual model show an excess nitrogen input of about 320 kg/ha/a. Nevertheless,both nitrogen species were only detected at low concentrations in shallow groundwater,averaging at 3.6 mg/L NH4-N and 1.8 mg/L NO3-N. Measurement results supported by PHREEQC-modeling indicated cation exchange, denitrification, and anaerobic ammonium oxidation coupled with partial denitrification as major nitrogen removal pathways. Despite the current removal capacity, the excessive nitrogen fertilization may pose a future threat to groundwater quality. Surface water quality improvements are therefore recommended in conjunction with simultaneous monitoring of nitrate in the aquifer, and reduced agricultural N-inputs should be considered.

关键词： Groundwater pollution North China Plain Surface water–groundwater interaction Wheat–maize double cropping Nitrogen Anammox

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Experimental Determination and Modeling of Bubble Size Distributions in Bubble Columns

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Chinese Journal of Chemical Engineering 1998年第1期6卷 33-45页

作者： H.F.Svendsen 罗和安 K.W.Hjarbo H.a.jakobsen Department of Chemical Engineering Norwegian University of Science and Technology Department of Chemical Engineering Xiangtan University SINTEF Applied Chemistry DNMI P.O.Box 43Blindern

Using a five point conductivity technique local values of bubble size,bubble velocity and gas fractionhave been experimentally determined in a 288 mmID and 4.3 m high bubble column as a function of axial andradial position for the air/water and CO2/N2/aqueous MDEA *** experimental results are comparedwith predictions from a fundamental two-fluid *** implementation of a non-steady lateral drag term inthe two-fluid model has been *** addition to improving the physical realism of the model,it is found togive slight improvements in the predictions of the distributions of local bubble *** of bubble size arefound in reasonable agreement with experimental values in the heterogeous flow regime,whereas they are stil1found to be unreliable at low gas *** void predictions are found in reasonable agreement with experi-mental values,but deviations occur in the homogeneous flow regime towards the *** is attributed to defi-ciencies in the simplified bubble size

关键词： Bubble column bubble size distribution volumetric velocity gas fraction two-fluid model

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Target-Oriented Inversion of Time-Lapse Seismic Waveform Data

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Communications in Computational Physics 2020年第6期28卷 249-275页

作者： Xingguo Huang Morten jakobsen Kjersti Solberg Eikrem Geir Nævdal Department of Earth Science University of BergenP.O.Box 78035020 BergenNorway NORCE Norwegian Research Centre Postboks 225838 BergenNorway

Full waveform inversion of time-lapse seismic data can be used as a means of estimating the reservoir changes due to the *** the repeated computa-tions for the monitor surveys lead to a large computational cost,time-lapse full wave-form inversion is still considered to be a challenging *** address this problem,we present an efficient target-oriented inversion scheme for time-lapse seismic data using an integral equation formulation with Gaussian beam based Green’s function *** proposed time-lapse approach allows one to perform a local inversion within a small region of interest(e.g.a reservoir under production)for the monitor *** have verified that the T-matrix approach is indeed naturally target-oriented,which was mentioned by jakobsen and Ursin[24]and allows one to reduce the compu-tational cost of time-lapse inversion by focusing the inversion on the target-area *** method is based on a new version of the distorted Born iterative T-matrix inverse scattering *** Gaussian beam and T-matrix are used in this approach to perform the wavefield computation for the time-lapse inversion in the baseline model from the survey surface to the target *** have provided target-oriented inversion results of the synthetic time-lapse waveform data,which shows that the proposed scheme reduces the computational cost significantly.

关键词： Waveform inversion time-lapse seismic seismic inverse scattering target-oriented inversion Gaussian beam based Green’s function

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Transition Operator Approach to Seismic Full-Waveform Inversion in Arbitrary Anisotropic Elastic Media

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Communications in Computational Physics 2020年第6期28卷 297-327页

作者： Morten jakobsen Ivan Psencık Einar Iversen Bjørn Ursin Department of Earth Science University of BergenNorway Institute of Geophysics Czech Academy of SciencesCzech Republic Department of Geoscience and Petroleum NTNU and F.University of BahiaBrazil

We generalize the existing distorted Born iterative T-matrix(DBIT)method to seismic full-waveform inversion(FWI)based on the scalar wave equation,so that it can be used for seismic FWI in arbitrary anisotropic elastic media with variable mass densities and elastic stiffness *** elastodynamic wave equation for an ar-bitrary anisotropic heterogeneous medium is represented by an integral equation of the Lippmann-Schwinger type,with a 9-dimensional wave state(displacement-strain)*** solve this higher-dimensional Lippmann-Schwinger equation using a transition operator formalism used in quantum scattering *** allows for domain decomposition and novel variational *** tensorial nonlinear inverse scat-tering problem is solved iteratively by using an expression for the Fŕechet derivatives of the scattered wavefield with respect to elastic stiffness tensor fields in terms of modified Green’s functions and wave state vectors that are updated after each *** the generalized DBIT method is consistent with the Gauss-Newton method,it incorporates approximate Hessian information that is essential for the reduction of multi-parameter cross-talk *** DBIT method is implemented efficiently using a variant of the Levenberg-Marquard method,with adaptive selection of the regularization parameter after each *** a series of numerical experiments based on synthetic waveform data for transversely isotropic media with vertical symmetry axes,we obtained a very good match between the true and inverted models when using the traditional Voigt *** suggests that the effects of cross-talk can be sufficiently reduced by the incorporation of Hessian information and the use of suitable regularization *** the generalized DBIT method for FWI in anisotropic elastic media is naturally target-oriented,it may be particularly suitable for applications to seismic reservoir characterization and ***,the theory a

关键词： Waveform inversion time-lapse seismic seismic inverse scattering target-oriented inversion Green’s function

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Techno-economic comparison of three technologies for precombustion CO2 capture from a lignite-fired IGCC

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Frontiers of Chemical Science and Engineering 2020年第3期14卷 436-452页

作者： Simon Roussanaly Monika Vitvarova Rahul Anantharaman David Berstad Brede Hagen Jana.jakobsen Vaclav Novotny Geir Skaugen SINTEF Energy Research NO-7465 TrondheimNorway Faculty of Mechanical Engineering Czech Technical University in Prague16607 Prague 6Czech Republic

This paper compares the techno-economic performances of three technologies for CO2 capture from a lignite-based IGCC power plant located in the Czech Republic:(1)Physical absorption with a Rectisol-based process;(2)Polymeric CO2-selective membrane-based capture;(3)Low-temperature *** evaluations show that the IGCC plant with CO2 capture leads to costs of electricity between 91 and 120€·MWh−1,depending on the capture technology employed,compared to 65€·MWh−1 for the power plant without *** results in CO2 avoidance costs ranging from 42 to 84€·tCO2,avoided−1,mainly linked to the losses in net power *** both energy and cost points of view,the low-temperature and Rectisol based CO2 capture processes are the most efficient capture ***,partial CO2 capture appears as a good mean to ensure early implementation due to the limited increase in CO2 avoidance cost when considering partial *** go beyond the two specific CO2-selective membranes considered,a cost/membrane property map for CO2-selective membranes was *** map emphasise the need to develop high performance membrane to compete with solvent ***,the cost of the whole CCS chain was estimated at 54€·tCO2,avoided−1 once pipeline transport and storage are taken into consideration.

关键词： carbon capture and storage(CCS) techno-economic comparison pre-combustion capture physical solvent low-temperature capture

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Comparison of a Reaction Front Model and a Finite Difference Model for the Simulation of Solid Absorption Process

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Journal of Thermal Science 1994年第2期3卷 136-141页

作者： Zikang Wu Arne jakobsen Xiugan Yuan PWors e-Schmid Group 505 Air-Conditioning and Refrigeration InstituteBeijing University of Aeronautics and AstronauticsBeijing 100083China Refrigeration Laboratory The Technical University of DenmarkDK-2800LyngbyDenmark

The purpose of this paper is to investigate the validity of a lumped model, i.e. a reaction front model,for the simulation of solid absorption process. A distributed model is developed for solid absorption process, and a dimensionless RF number is suggested to predict the qualitative shape of reaction degree profile. The simulation results from the reaction front model are compared with those from the distributed model solved by a finite difference scheme, and it is shown that they are in good agreement in almost all casest no matter whether there is reaction front or not.

关键词： solid absorption simulation reaction front RF number reaction degree profile.

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