Projects

General description

Research in Chemical engineering covers fundamental studies of heat, mass and momentum transfer, technical thermodynamics, balances, unit operations and their applications in developing and designing new chemical processes and production plants. Research group exercises with phenomena based mathematical modeling and simulations are used to familiar students to chemical engineering methods in various industrial sectors chemical, oil, medical, pulp, bio etc..

Process development

Chemical engineering research group has long experience in process modeling, simulation and process design and development. This includes both software development and experiments in laboratory and mini plant scale. Several new unit models have been developed that combine both reaction step and separation step in an efficient way, for instance reactive distillation. Applications of these ideas are commercialized in environmentally friendly fuels production processes that are now licensed by Neste Oil in Europe and USA. Recently these fundamental modeling approaches have been directed towards reactive fiber and biomass systems encountered in pulping and bioprocessing.

Phase equilibria modeling and measurements

Accurate phase equilibrium (VLE/LLE) models are essential in the design of separation processes. These models are required both in the very preliminary and final phases of process designs. Research group has built several laboratory equipments for vapor/liquid and liquid/liquid measurements that are applicable in wide temperature, pressure and concentration area. Specific software to analyze the experiments and to develop mathematical models is available. Research started with applications in hydrocarbon and chemical systems, recent activities cover gas solubility in pulping liquors.

Mass transfer modeling and measurements

Many chemical processes are determined by the rate of mass transfer between phases. This is typical not only for separation processes but also for many multiphase reactors. Detailed general mass transfer models have been built and efficient calculation schemes developed for these models. New mass transfer models have been applied in wide application range covering both multiphase reactors (fermentors, trickle bed, bleaching) and separation processes (distillation, crystallization). New unit operation models for pulping processes are under development. These models contain detailed mass transfer and reaction models for reactive fiber suspensions.

Fluid flow modeling of reactive multiphase flows

Trickle bed reactors have attracted considerable attention recently due to their widespread use in environmentally friendly fuel production processes. In trickle bed reactors, gas and liquid flow through a bed of solid catalyst particles, in which complicated interactions between the phases take place. These interactions include mass- heat- and momentum transfer between all three phases, with complex cross-effects. All the relevant interactions need to be modeled accurately for reliable reactor design. In order to accomplish this, a cold flow trickle bed apparatus has been built in the laboratory. It is designed so that relevant hydrodynamic parameters for the reactor design can be measured and applied for large-scale reactor simulations. Knowledge of the reactive flow in fixed bed structures gives adequate background to expand to reactive flows in moving fiber beds of pulping processes.

Population balances

Population balance modeling is the most fundamental approach for describing particulate phase property distributions resulting from breakage, agglomeration and growth. Recently high-order category methods have been developed in our research group for solution of these integro-partial differential equations. These methods are several orders of magnitude more accurate than the state of the art low order methods. This increased accuracy allows a significant reduction in the number of categories compared to the currently adopted methods, bringing the population balances closer to practical use.

Ongoing projects

Projects in Research Group of Chemical engineering

  1. Phase Equilibria for Bio-refineries (PEQBIO)
  2. Crystallization  - FLUKI
  3. Academy Research Fellow Project: Process development intensification by utilization of a new generation of Micro-plants
  4. Physical Properties and Phase Equilibria Measurements for Pyrolysis Oil Components
  5. Phase Stability Calculation and Equilibrium Measurements for Biorefinery
  6. Fubio Joint Research 2 / Ionic Liquids
  7. Fubio Joint Research 2 / Modelling of Hot Water Extraction
  8. Products from dissolved cellulose / Modelling of viscose process
  9. CLEEN- Carbon Capture and Storage

Phase Equilibria for Bio-refineries (PEQBIO)

Researchers at Aalto:

  • FiDiPro Professor Dominique Richon
  • Post-Doc., D.Sc. (Tech.) Hernando Guerrero
  • Doctoral candidate, M.Sc. (Tech.) Muhammad Saad Qureshi
  • Academy research fellow, D.Sc.(Tech.) Petri Uusi-Kyyny
  • Teaching researcher, D.Sc.(Tech.) Juha-Pekka Pokki

Duration:

January 2013 - December 2015

Partners:

  • CET/TEP at MINES ParisTech in Paris, France
  • Neste Oil
  • Neste Jacobs
  • Borealis Polymers
  • UPM-Kymmene

Funding:

  • TEKES
  • Companies

Phase equilibrium models and measurements form an essential basis needed for designing processes where biomass related products are converted into biofuels and value-added chemicals. These conversion processes often occur at high temperatures and pressures. In such systems, phase equilibria measurement and sampling is one of the major challenges. Additionally a characteristic feature of bio-refinery systems is that water is always present in discernible quantities. There is a great lack of: phase equilibrium measurement equipment, researchers who can do the measurements reliably and the data itself. This project aims at improving the situation in Finland. Thermodynamic models already available will be utilized by regression of model parameters to describe the systems measured. 

Crystallization - FLUKI -project 

Researchers at Aalto:

  • M.Sc. Zhao Wenli
  • D.Sc.(Tech.) Kaj Jakobsson

Duration:

  • September 2012 - August 2016

Funding:

  • Academy of Finland

Research consortium:

  • Aalto University, Prof. Ville Alopaeus, consortium leader 
  • Lappeenranta University of Technology, Prof. Marjatta Louhi-Kultanen
  • VTT, Technical Research Centre of Finland, Industrial, D.Sc. (Tech) Mikko Manninen

Description:

Crystallization and precipitation are important unit operations both in manufacturing of solid materials, such as pharmaceutical compounds, or in separation of chemical components with varying solubility and/or melting point. 

The objective of the FLUKI project is to study interactions between the fluid flow and crystal properties. Fluid flow and micromixing affect strongly on the crystallization and precipitation kinetics and product quality, but on the other hand the solid particles affect the slurry rheology. Both of these interactions are studied in this project in multiple length scales. The largest scales are related to the whole crystallizer size, which can be several cubic meters in volume. The smallest scales are on the order of individual crystal sizes that can be only a few micrometers. In case of crystal morphology, the relevant length scales are on the order of single chemical bonds.

The research is divided to three main work packages between the consortium members:

  1. Comparison of the crystallization in tubular precipitators and in the stirred tanks by using L-glutamic acid and magnesium carbonate, Lappeenranta University of Technology 
  2. Population balance modeling of crystallization and precipitation, Aalto University
  3. Computational fluid dynamics (CFD) analysis of tubular precipitators and stirred tank crystallizers. VTT, Technical Research Centre of Finland

At the Aalto University the population balance models are formulated for the crystallization and precipitation. They include all relevant phenomena, most important being the primary nucleation from the supersaturated solution and crystal growth.

The high order moment conserving method of classes (HMMC) is implemented in various platforms of , namely to the multiblock model and CFD. Also reduced models predicting mainly some important integral variables of the distributions, most notably its moments, are applied. In another FLUKI approach only the moments are modeled instead of the true distribution.

Academy Research Fellow Project: Process development intensification by utilization of a new generation of Micro-plants

Researchers:

  • Petri Uusi-Kyyny
  • Saeed Mardani
  • Mikko Ojala

Duration:

  • September 2011 - August 2016

Funding:

  • Academy of Finland

Description:

The main objective of this project is to develop a methodology for the intensification of process development for processes which have distillation and/or absorption as the separation process. The reduction of the following costs: equipment, building, space, feedstock and personnel by at least 80% compared to current mini-plant technology will be pursued with the methodology to be developed. Also safety issues will be improved due to the small amount of feedstock needed. The information obtained from micro-plants with recycle streams will be as abundant as which can be obtained from mini-plants since the phenomena in the unit processes are the same as in the larger scale.

The second objective is to explore the opportunities of new manufacturing methods for speeding up the manufacture and lowering of the cost of the specifically tailored integrated small scale process units and instrumentation.

The third objective is to prove the feasibility of the approach through case studies. The first case will consist of a reactor and distillation unit with a recycle stream. The second case is an absorber stripper set-up for carbon capture from flue gases.

Physical Properties and Phase Equilibria Measurements for Pyrolysis Oil Components

Researchers:

  • Erlin Sapei
  • N.N.

Duration:

  • September 2011 - August 2014

Funding:

  • Academy of Finland

Description:

Researches on biomass pyrolysis oil components for biofuel production development are focused on physical properties measurements and phase equilibria measurements that are needed for thermodynamic modeling of primary compounds and their mixtures existing in pyrolysis oils. This knowledge is prerequisite for the design of efficient and environmentally friendly separation processes in biorefinery. For that purpose, the Knudsen effusion apparatus is built for measuring vapor pressures of pure compounds and their mixtures.

Phase Stability Calculation and Equilibrium Measurements for Biorefinery

Researchers:

  • Juha-Pekka Pokki
  • Helena Laavi
  • Anna Zaitseva

Duration:

  • September 2011 - August 2015

Consortium:

  • Phase Stability and Equilibrium

Partner:

  • University of Oulu

Description:

The aim of the project is to develop the calculation methods for the multiphase systems that are needed in the design of the biorefinery processes. The developed calculation methods are very important because there exists several phases at high temperature and pressure. The experimental part of the project produces phase equilibrium data.

FuBio Joint Research 2 / Ionic Liquids

Researchers:

  • Erlin Sapei
  • N.N.

Duration:

  • June 2011 - May 2014

Funding:

  • M-Real

Coordinator

  • Forestcluster Ltd.

Description: 

In biorefinery processes, ionic liquids (ILs) will get mixed with other product streams and will have to be separated and recycled. Economically and ecologically it is important to recycle and re-use ionic liquids as efficiently as possible. In order to design optimal separation sequences for distillable ionic liquids, physical properties for the separated components are needed. Two approaches are selected: First is phase equilibria measurement of binary IL + product systems using a static total pressure method. Second is vapor pressure measurement of pure ILs using Knudsen effusion method. The Knudsen effusion apparatus is under construction phase and will be tested from beginning of the February 2012. The apparatus will be tested by measuring vapor pressure of pure organic compounds and validated with available data from literature.

FuBio Joint Research 2 / Modelling of hot water extraction

Researchers:

  • Waqar Ahmad
  • Susanna Kuitunen

Duration:

  • June 2011 - May 2014

Funding:

  • Tekes

Coordinator

  • Forestcluster Ltd.

Description:

A unified framework based on population balances is formulated for modeling of biooriginating polymer chain length distributions in various processes relevant to biorefineries. The model describes chain lengths as discrete size categories where the rate of change of number concentrations for various polymer chain lengths is accounted. Detailed kinetics relevant to chain breakage and other chain property modifications are included. The actual set of reactions needed depends on the application. In addition, physical modeling of the processes, based on material, energy, and population balances, thermodynamics, transport phenomena and chemical kinetics is carried out. The process application in this project is pressurized hot water extraction (PHWE).

Products from dissolved cellulose / Modelling of viscose process

Researchers:

  • Waqar Ahmad
  • Susanna Kuitunen

Duration:

  • June 2011 - May 2014

Funding:

  • Metsä Fibre

Coordinator:

  • Forestcluster Ltd.

Description: 

A unified framework based on population balances is formulated for modeling of biooriginating polymer chain length distributions in various processes relevant to biorefineries. The model describes chain lengths as discrete size categories where the rate of change of number concentrations for various polymer chain lengths is accounted. Detailed kinetics relevant to chain breakage and other chain property modifications are included. The actual set of reactions needed depends on the application. In addition, physical modeling of the processes, based on material, energy, and population balances, thermodynamics, transport phenomena and chemical kinetics is carried out. In this project the goal is to model processes utilizing cellulose as the raw material, for instance viscose production.

CLEEN - Carbon Capture and Storage

Researchers:

  • Anne Penttilä
  • Kaj Jakobsson

Duration:

  • 2011 - 2015

Funding:

  • Tekes
  • CLEEN Ltd

Description:

The laboratory is a research partner in the Carbon Capture and Storage Program managed by CLEEN ltd established in 2008 to facilitate and coordinate world class industry driven research in the field of energy and environment (http://www.cleen.fi/home/).

The chemical engineering research group contributes to the project by studying the removal of CO2 from combustions gases as this is an important technological alternative in addressing the global climate challenge.

In the project the absorption regeneration cycle of CO2 -capture with chemisorption (mixtures of amines) is studied.  This includes the study of properties of mixtures of amines, loading, efficiency (reaction rate) and regeneration of the solvent. The process has also other important aspects such as the high energy demand for solvent regeneration, degradation of the solvent, and corrosion.

The final target is to implement a state of the art model for CO2 processes for simulation, analysis and design amine -processes based on the knowledge obtained in the project.

 

Projects ended

  1. VIC - Virtual Chemical Pulping Model
  2. Heavy oil
  3. Modeling of acid gas + water + alkanolamine vapor-liquid equilibrium (VLE)
  4. Fubio
  5. EFFMIND - Efficient Models for Industrial Gas-Liquid-Solid Processes
  6. Bioscen
  7. Biorefinery
  8. Dynamic modelling for multiphase reactors
  9. VIP - Virtual Pulp Bleaching 
  10. Regal - Modeling of reactive gas-liquid flow in porous media
  11. Modelling nickel heap bioleaching process
  12. Transport phenomena in swelling resins
  13. Reactor modelling of Fischer-Tropsch synthesis to produce environmentally sustainable bio based transportation fuels
  14. Micro Plant/FABTecH
  15. LOVI - Combining multiblock and detailed fluid flow models 

 

VIC - Virtual Chemical Pulping Model

Researchers:

  • Susanna Kuitunen

Duration:

June 2010-June 2013

Funding:

  • FIBIC (Forestcluster)
  • TEKES

Partners:

  • Aalto University, Department of Forest Products Technology, Wood Chemistry, prof. Tapani Vuorinen
  • University of Jyväskylä, Department of Chemistry, Laboratory of Applied Chemistry, prof. Raimo Alen

Description:

VIC is part of the Forestcluster's EffFibre program:

http://www.forestcluster.fi/d/content/value-through-intensive-and-efficient-fibre-supply-2010-2013

The two main objectives of VIC is to create in-depth knowledge on the existing and possible new cooking processes, and to create a tool for understanding the behaviour of wood chips and their constituents in a wide variety of chemical conditions. VIC models are impleted into the in-house Flowbat software.

Heavy oil

Researchers:

  • Claudia Dell'Era
  • Petri Uusi-Kyyny
  • Piia Haimi
  • Meri Saajanlehto
  • Minna Pakkanen
  • Kaj Jakobsson

Duration:

  • 2010 - August 2012

Funding:

  • Neste Oil

Description:

It is common in the oil industry to mix crude oils or blend them with other hydrocarbons to achieve, for instance, a lower viscosity for transport through pipelines. In addition, crude oils from different sources are often mixed before refining. If the blended fluids are incompatible, asphaltene might precipitate. The deposit of asphaltene may cause plugging and fouling in pipelines and refinery units. Therefore, predicting the stability of asphaltene in crudes is of great interest for the oil industry.
In this project, the solubility of asphaltene in crude oils is modeled taking into account the effects of oil composition and of gas absorption on asphaltene precipitation. Experimental work supports the development of the model with focus on the role played by absorbed gas. A phase equilibrium measurement apparatus is constructed for measuring gas solubility in hydrocarbon mixtures. The measurement conditions are challenging with temperatures up to 450°C and pressures up to 15 MPa. At such high temperatures cracking reactions are expected; therefore a static cell should not be used. A dynamic method was instead selected for the measurements.

 

Modeling of acid gas + water + alkanolamine vapor-liquid equilibrium (VLE)

Researchers:

  • Anne Penttilä
  • (Claudia Dell'Era, Petri Uusi-Kyyny)

Duration:

  • 2010-2011

Funding:

  • Finnish Foundation for Technology Promotion (TES)

Desription:

The absorption of CO2 and H2S from gas streams is an important operation in the natural gas and synthetic ammonia industries, in oil refineries and petrochemical plants. H2S is removed from gas streams due to its toxicity, its tendency to poison the catalysts and to cause corrosion in process equipment, while CO2 lowers the heat value of natural gas. The role of CO2 as a greenhouse gas has also resulted in tightening environmental regulations concerning CO2 emissions to the atmosphere. CO2 capture is one of the most significant means to reduce such emissions. In gas sweetening, natural gas is coptacted counter currently with an aqueous alkanolamine solvent in an absorber column. The acid gas dissolves both physically and chemically into the solvent. The amine solvent is then regenerated at elevated temperature in a stripper unit. In simultaneous design of absorbers and strippers accurate thermodynamic models are needed to characterize the vapor-liquid equilibrium of acid gas + water + amine systems.
The work in the field of alkanolamine started in 2004. Claudia Dell'Era was founded by Fortum foundation from 2004 to 2007 and the project also received two years funds from the Finnish Foundation for Technology Promotion (2008-2010). During the initial stages of the project it was acknowledge that lack of experimental data limited the performances of thermodynamic models of alkanolamine systems. In particular, it was found that experimental data of diisopropanolamine (DIPA) are scarce in the literature, even thought DIPA is widely used by refineries in Europe. Several experimental techniques were developed to measure C02 solubility in amine solutions and binary VLE and SLE data of water + amine systems. The binary water + amine systems were successfully modeled. All data and modeling results were published.

Currently, the focus of the project is on modeling the ternary systems (gas + water + amine) by means of a new expression of the Henry's law of carbon dioxide in amine solutions and of an electrolyte activity coefficient model. Experimental measurements of the solubility of H2S in amine solutions will also be performed.

 

FuBio

Researchers:

  • Juha Visuri
  •  (Susanna Kuitunen)

Duration:

  • 2008 - 2011

Funding:

  • Forestcluster Ltd.

Description:

The future biorefinery concept aims at the fractionation of wood to its components, which are cellulose, hemicellulose, and lignin and at upgrading them further into chemicals and novel materials. The objective of Future Biorefinery project is to create a world-leading knowledge platform in the field of wood biorefinery R&D (http://www.forestcluster.fi/d/content/future-biorefinery).

Juha Visuri developed a model for the depolymerization of hemicelluloses in hot water extraction conditions in his M.Sc. thesis. The model was implemented to be part of the computational tool for wood pulping and pulp bleaching developed in ABLE, VIP and on-going VIC projects. In future, a unified framework based on population balances is formulated for modeling of polymer chain length distributions of bio-originated polymers in various processes relevant to biorefineries.

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EFFMIND - Efficient Models for Industrial Gas-Liquid-Solid Processes

Researchers:

  • Elina Nauha

Duration:

  • 2009-2011

Funding:

  • Neste Jacobs
  • Neste Oil
  • Outotec Minerals Oy
  • Outotec Oyj
  • Talvivaara Oyj
  • TEKES

Partners:

  • TUT (Energy and Process Engineering
  • Aalto University (Mechanical Processing and Recycling)
  • VTT

Description:

The EFFMIND project aims at developing new efficient methods for
modeling practical industrial three-phase reactors. The focus is on
computationally efficient but still predictive models. Computational
Fluid Dynamics (CFD) is vigorously utilized as a tool in this
project. A previously developed multiblock model will be improved and
developed towards a practical simulation tool for industry.

Several types of three-phase processes are considered including froth
flotation, three-phase stirred reactors, slurry reactors, fixed beds
and algae cultivation. Experimental work is carried out both for
developing physical models and for the validation of multiblock and
CFD models.

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Bioscen

Researchers:

  • Anna Zaitseva
  • Petri Uusi-Kyyny

Duration:

  • 2008-2011

Funding:

  • TEKES

Industrial partners:

  • Metso Power Oy
  • Neste Oil Oyj
  • Pöyry Engineering Oy
  • Vapo Oy

Cooperation:

  • VTT Technical Research Centre of Finland, Prof. Pertti Koukkari
  • University of Jyväskylä, Prof. Kaisa Miettinen

Background:

In chemical technology, it is customary that no new processes are designed without constructing a simulation model. With advanced models, erroneous trials and costly experimental work can be minimized. The materialization of the biorefinery also necessitate development of industrial methods, based on chemical engineering. Modern thermodynamic models serve both improved understanding of various reaction networks including unit processes thereof and construction of reliable balance (flowsheet) models to evaluate the feasibility of industrial production units.

Bioscen project develops methods for modelling of biorefinery concepts. The project covers a range of modelling approaches starting from collecting and predicting minute details of molecular properties of biorefinery chemicals to optimizing energy efficiency and estimating the life cycle analysis of a complete biorefinery production plant.

Design and development of industrial biomass related processes typically require measured data of material properties and phase equilibrium (vapor/liquid, liquid/liquid or gas solubility in liquids), densities, viscosities and other thermodynamic and transport properties. When measured data is not available estimation methods are used. Efficient design and development is carried out using modeling and simulation. A theoretically well based predictive method can save a lot of time and money providing good quality estimations data without experiments. COSMO-RS model is based on Quantum Mechanical calculation of molecule state in fluid and thus provides good estimation of many physico-chemical properties of compounds based only on their molecule structure.

Objectives:

Our laboratory research is focused on molecular propeties database, gathering and predicting property values of the molecules in the selected biorefinery areas, and modelling condensation of pyrolysis oil.

Work:

In this work collection of physico-chemical properties for representative compounds of pyrolysis oil is gathered from all available sources, both electronic and printed. Quality of the data is analyzed. Unavailable properties or poor quality data are estimated with Group Contribution Methods (Marrero-Pardillo [1], Nanoolal [2], Joback- Stein [3]) and with COSMO-RS[4,5].

Calculation of pyrolysis oil condensation can be made based on knowledge of vapor liquid equilibria for all system component binaries. Search for binary system containing components of pyrolysis oil is made. Information about 14 binary containing model compounds was found in literature. The data is used for fitting UNIQUAC binary interaction parameters. For systems where data was not available in literature, pseudo experimental data were generated by COSMO-RS model. Modeling of condensation of pyrolysis oil is made by combining different approaches for modeling liquid and vapor phases. Equation of state, Gibbs excess energy models and their combinations are tested. High flow of carrier gases in pyrolysis oil condenser effects considerably distribution of liquid components between vapor and liquid phase, the gases are taken into calculation by ideal low or Henry's law models.

Bibliography:

[1] Marrero-Morejon, J. and Pardillo-Fontdevila, E., 1999. Estimation of pure compound properties using group-interaction contributions. AICHE Journal, 45(3), 615-621.
[2] Nannoolal, Y., Rarey, J., Ramjugernath, D. and Cordes, W., 2004. Estimation of pure component properties: Part 1. Estimation of the normal boiling point of non-electrolyte organic compounds via group contributions and group interactions. Fluid Phase Equilibria, 226, 45-63.
[3] Stein, S.E. and Brown, R.L., 1994. Estimation of normal boiling points from group contributions. Journal of chemical information and computer sciences, 34(3), 581-587.
[4] Klamt, A., 1995. Conductor-like Screening Model for Real Solvents: A New Approach to the Quantitative Calculation of Solvation Phenomena. Journal of Physical Chemistry, 99(7), 2224-2235.
[5] "COSMOLOGIC GMBH & CO", 2009. COSMOtherm, Version C2.1, Release 01.10. Leverkusen, Germany.

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Biorefinery

Researchers:

  • Zheng Liu

Duration:

  • 2008-2011

Funding:

  • Academy of Finland
  • UPM-Kymmene Oy

Partners:

  • Aalto, Plant Design & CleanTech-group

Description:

The general objective of this project is to create new generation bio-refinery concepts connected to an urban area or industrial site. Chromatography process is used so that certain commercially useful sugars are separated from the by-product of bio-refinery process. Chemical Engineering group's focus is the simulation of the chromatography process based on the general rate model. The numerical tool applied is the moment transformation method.

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Dynamic modelling for multiphase reactors

Researcher:

  • Helena Laavi

Duration:

  • 2006-2010

Funding:

  • Neste Jacobs
  • Graduate School of Chemical Engineering (GSCE)

Background:

Process models are an important tool in process development. In order to meet the strict requirements in today's industry, it is important to develop new and more accurate process models which are planned to better model the specific characteristics of the process. In addition, these accurate models are necessity for process development. Through these models the process can be optimized. By simulating unusual situations the process safety issues can be improved.

An important field of using multiphase reactors involves hydrocarbon hydrogenation reactions in petrochemical industry. These reactions are exothermic and the reaction heat release is higher than the energy needed for vaporization of the undiluted reacting liquid phase. This can result in local catalyst drying and formation of hot spots. If the reaction undergoes a phase change the catalyst temperature can rise remarkably as there is no liquid phase available that could bind the reaction heat. In addition, the heat transfer in vapor phase is slow which further contributes to the local overheating.

In the formation of hot spots, a deviation from normal reaction conditions occurs and this disturbance can launch a larger scale malfunction of the reactor. Therefore it is important to know if even relatively small scale disruptions can have serious effects in the larger scale process. There is also evidence that reactor runaways have started particularly from local hot spots.

Objectives:

A new dynamic model is developed including the mass transfer effects and specific phenomena of phase changes. The challenges of robust modelling despite the instability of runaway reactions is one of the main aims of the study. More accuracy for the model is obtained through fluid dynamic calculation.

Challenges:

The simultaneous calculation of mass transfer and phase changes will cause computational problems. During a phase change when another phase disappears, discontinuations in any other part of the model are not allowed because they may cause difficulties to solve the model. In addition, the instability of runaway reactions will challenge the model.

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VIP - Virtual Pulp Bleaching

Researchers:

  • Susanna Kuitunen
  • Ville Tarvo

Duration:

  • 06/2008 - 06/2010

Funding:

  • TEKES
  • Forest Cluster

Partners:

  • TKK, Forest Chemistry
  • VTT
  • KCL
  • LUT
  • UMaine

Description:

Virtual pulp bleaching project focus is on accomplishing a virtual pulp bleaching plant that is a simulation tool for piloting of different options of sequences and process conditions in pulp bleaching. The simulation tool can be used in fast and cost-effective development of next-generation bleaching processes that are characterized by low capital investments, low operation costs and low environmental load.

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Regal - Modeling of reactive gas-liquid flow in porous media

Researchers:

  • Katja Lappalainen
  • Susanna Kuitunen
  • Heli Nikiforov

Duration:

  • 1.4.2006 - 31.3.2009

Partners:

  • VTT Processes

Funding:

  • Andritz
  • Fortum
  • Metsä-Botnia
  • TEKES

Objectives:

The objective of this project is to study the fundamental small-scale phenomena related to fluid flow in porous media particularly in catalyst beds and pulp suspension, with an emphasis in reactive conditions. General interaction models will be developed so that the scale dependency is included in the models. Verification of these models is carried out against experimental measurements.

The detailed small-scale models are combined within various reactor modeling frameworks with an ultimate goal of predicting reactor performance in industrial scale and in wide range of operating conditions.

Trickle-bed reactors:

Closure models for phase interactions are developed based on experimental data and CFD modeling (FLUENT), which are validated against large literature database using analytically solvable model. Models for small scale phenomenon, such as capillary and mechanical dispersion, are under development and will be implemented to the CFD models so that the scale dependency is inherently included in the model, which will decrease the errors in scale-up.

Ultimate goal is to develop a pressure drop solution that is usable in industrial scale and implementable to design tools suitable for flowsheeting programs (e.g. FLOWBAT) that are more suitable for industrial-scale reactor modeling.

In addition to aforementioned modeling options (CFD, analytically solvable model and flowsheeting programs) also a cellular automata model, which was developed in the preceding project on trickle-bed reactors, can be used for statistical analysis of the liquid flow patterns.

Fiber-beds:

In pulp and paper industry, many processes are comparable to one- or two-phase flow through porous media (delignification of pulp, cooking, bleaching, washing). The complicity of fiber-beds lies in their unhomogeneous nature and the scale-up of related processes has been known to be error-prone. The experience gathered in research on trickle-beds will be used as a foundation on fiber-bed modeling, which, combined with one- and two-phase flow experiments in fiber-beds (small-scale phenomenon as well as global hydrodynamics), will be used to develop a new model that will take into account the key features of fiber-beds.

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Modelling nickel heap bioleaching process

Researchers:

  • Timo Seuranen
  • Kaj Jakobsson
  • Jouni Touronen

Duration:

  • 2007-2009

Funding:

  • TEKES

Description:

Bioleaching is a process, whereby metals are leached from ore as a result of bacterial action. In nature, bioleaching is triggered spontaneously by micro-organisms in the presence of air and water. Commercially applied bioleaching technologies utilize the same phenomenon, but accelerate this natural process. Several physicochemical and microbiological process parameters are modified in order to enhance and speed up the metal recovery process.

After the agglomeration, the ore will be conveyed and stacked eight to ten meters high on the primary heap pad for one and one-half years of bioheapleaching. The heap pad will be equipped with piping, laid on the bottom of the pad, through which low-pressure fans can supply air to the stacked ore. From the top, the heap will be irrigated with leach solution, which will be recycled through the heap until its metal content is sufficient for metals recovery.

In metals recovery, nickel, copper, zinc and cobalt are precipitated from the pregnant leach solution and filtered to produce saleable metal products. After the metals are removed, the solution is further purified and returned to irrigate the heaps.

The aim of this project is to model the key parameters of the bioleaching process. The dynamic heap bioleaching model will be a part of the flowsheeting program Flowbat and will be used for design, analysis and optimisation of the process.

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Transport phenomena in swelling resins

Researchers:

  • Anna Zaytseva
  • Petri Uusi-Kyyny

Duration:

  • 2006-2008

Funding:

  • Neste Jacobs

Background:

Ion-exchange resins are widely used in many industrial processes from bio and chemical production to water purification. They are also used for recovery of chemicals, waste treatment and as catalysts for production of fuel oxygenates (iso-octane, MTBE, ETBE, TAME and other esters, ethers and alcohols). The ion exchange resins are typically delivered as water saturated and they have a strong tendency to adsorb polar compounds like water or alcohols. Adsorption of polar components can cause a significant swelling of resin particles, which, in turn, changes the volume of resin layer. Rate of the catalyzed reactions is determined by resin swelling due to change of accessibility of active sites and concentration of the oxygenates inside the resin. Swelling of the catalyst particles and local component concentration makes prediction of reaction rates demanding. Detailed understanding of resin swelling and dynamics of polar component removal is essentially important for safe reactor operation and start-up.

Objectives:

Simulation of water removal from resin particles at the reactor start - up is one of the main goals of the modeling. Another important direction of the modeling is description of local inhomogeneity inside the fixed bed reactors related to channeling and hot spot formation.

Work:

In this work, a detailed phenomenological model is developed to investigate behavior of resin catalyst particles in fixed bed reactors. The model includes dynamic description of mass and heat transfer by multi - block model. Resin catalyst particles are considered as separate phase where mass transfer is described by Maxwell-Stefan diffusion model. Swelling and shrinking of the particles are described with three-chain model of elastic networks. Multifunctional laboratory scale equipment was built to validate the developed model. Effects of temperature, flow rate, fluid concentration on resin swelling and reaction rates were investigated in tubular glass tube. The product flow and catalyst swelling/shrinking were analyzed in-line by GC and photographing methods.

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Reactor modelling of Fischer-Tropsch synthesis to produce environmentally sustainable bio based transportation fuels

Researcher:

  • Kaj Jakobsson

Duration:

  • 2006-2008

Funding:

  • Neste Jacobs
  • TEKES

In Fischer-Tropsch (FT) synthesis carbon monoxide and hydrogen are converted into liquid hydrocarbons. This process is a promising route to produce environmentally sustainable transportation fuels in combination of biomass gasification and gas treatment. The reactor model will be a part of the flowsheeting program Flowbat and will be used for design, analysis and optimisation of the whole FT process.

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Micro Plant / FABTech

Researcher:

  • Aarne Sundberg

Duration:

  • 2007-2011

Description:

Micro process technology is the use of microstructured components in the process industry. The characteristic diameter of microstructured components is millimeters or less which makes the volume of the components very small and the process inherently safer. The high surface-to-volume ratio allows more efficient thermal transfer which makes controlling the process easier. Because of small size and thin piping a micro plant is easier to build than a conventional pilot plant. This offers savings both in the investment cost and in the development time. A micro plant also requires less supervising and it's chemical and energy costs are lower. The reaction studied in the micro plant is dimerization. The product flow from the reactor is distilled with a continuous micro distillation column and the unreacted feed is returned. The height equivalent of a theoretical plate of the column is 15 mm.

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LOVI - Combining multiblock and detailed fluid flow models

Researchers:

  • Pasi Moilanen
  • Olli Visuri

Duration:

  • 2006-2009

Funding:

  • TEKES
  • MASI-project

Description:

In order to accurately model heterogeneous reactors (e.g. fermentation, flotation and crystallization) local flow conditions need to be calculated. With Computational fluid dynamics (CFD) it is possible to model fluid flow in great detail, the drawback is that this requires massive computing and is only able to calculate around 1 minute of reactor time in a week or a steady-state solution.

The solution is to calculate the flowfield with CFD and then automatically transfer the results to a simpler multiblock model. In the multiblock model the flowfield is assumed to remain relatively constant and long calculations (many days) with detailed physical models can be made with reasonable computing times. Another goal of this project is to develop phenomenological models to describe phase-interactions and the effect of turbulence on the fluid flow.

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