Pertti Koukkari - Academia.edu (original) (raw)
Papers by Pertti Koukkari
Computers Chemical Engineering, Jul 1, 2011
Modeling rate-controlled chemically reactive systems in biocatalysis, fuel combustion, material s... more Modeling rate-controlled chemically reactive systems in biocatalysis, fuel combustion, material science, and chemical process engineering involves the quantification and exploitation of interactions between many chemical species. These dynamic chemical systems, having relatively few limiting reactions, can be conceived as a series of snapshots where reactions have fixed extents but otherwise idle. Since the reactions affect the stoichiometric matrix of the internal constraints, such constrained equilibrium states cannot be defined in terms of conventional atomic mass balances.A systematic method for obtaining generalized equilibrium constraints for reaction mechanisms of arbitrary complexity is presented. Reaction matrices are converted into entity conservation matrices using row operations. The simultaneously introduced virtual components enable Gibbs energy calculations for complex reaction schemes including organic systems and enzyme-catalyzed biochemical transformations having multiple limiting reactions. Classical Gibbs energy minimization, which would otherwise readily model phase transformations and solvent interactions, is thereby made accessible to these emerging application fields.
Journal of Solution Chemistry, Jan 7, 2002
The ion exchange processes, which occur when two compartments of aqueous solutions separated by a... more The ion exchange processes, which occur when two compartments of aqueous solutions separated by a semi-permeable interface are placed in aqueous electrolyte solutions, were modeled by using the multi-phase Gibbs energy minimization method. The Gibbs energy minimization method was applied for the ion exchange system consisting of pulp fibers and the surrounding aqueous bulk solution, where the anionic acid groups inside the fibers cause an uneven distribution of ionic species between the solution within the fiber walls and the solution external to the fibers. The method was tested with four cation concentrations, which are naturally present in the fibers and whose partitioning between the fiber phase and the external solution phase has been described earlier. Though the Donnan distribution constant is not explicitly calculated in the Gibbs energy minimization model, the results are consistent with the Donnan equilibrium theory. With the Gibbs energy minimization multi-phase model the formation of solid precipitates can also be calculated.
ABSTRACT Models based on free energy minimisation have been made for surface and interfacial syst... more ABSTRACT Models based on free energy minimisation have been made for surface and interfacial systems, where the surface, interfacial or adsorbed atomic or molecular layers are modelled as separate phases. Gibbs-Duhem compatible activity coefficients for the surface and interfacial layers are estimated based on known bulk thermodynamics and geometric and other considerations. The models allow the estimation of the surface energies and compositions [1] of mixtures based on pure component and bulk thermodynamic data and interfacial energies based on bulk thermodynamic values. In an analogous fashion the partitioning effect of a semi-permeable membrane in a two-compartment aqueous system can be modelled. In such system the large ions, not permeable through the membrane, cause an uneven charge distribution of ionic species between the two compartments. In this case, the electrochemical potential difference between the two aqueous phases becomes calculated for the multi-component system. The calculated results are consistent with the Donnan equilibrium theory; however the multi-phase system may also include the gas phase and several precipitating phases, which extends the applicability of the new method [2]. The interfacial models are solvable in a single equilibrium calculation by using a traditional Gibbs energy minimising program. Various example cases and applications in industrial practice will be presented. References: [1] R. Pajarre, P. Koukkari, T. Tanaka, Y. Lee: Calphad, 30, (2006) 196-200. [2] R. Pajarre, P. Koukkari, E. Rsnen: Journal of Molecular Liquids, 125 (2006), 58-61.
ABSTRACT Development of robust and efficient methods for the computation of multi-phase systems h... more ABSTRACT Development of robust and efficient methods for the computation of multi-phase systems has long been a challenge in both chemical and petroleum engineering as well as in materials science. Several techniques have been developed, particularly those which apply the Gibbs free energy minimization. In addition to calculation of global equilibrium problems, practical simulation of multi-phase chemical reactors would benefit from such multiphase algorithms, where reaction rates are taken into account. In the present work, the method of Lagrange multipliers has been used to incorporate such additional constraints to the minimization problem, which then allow reaction rate models to be included in the Gibbsian multi-component calculation /1, 2/. The extension of the conservation matrix brings about the possibility to include reaction kinetic restrictions to control the extents of chemical reactions in terms of their affinity. A generic algorithm which combines the Gibbs energy of the control volume system with the salient heat and mass transfer and reaction rates has been developed. The method has been used for several scale-up studies of complex chemical reactors with simultaneous chemical reactions and phase changes. The model has been validated with both thermodynamically consistent data and with practical plant measurements. An industrial case example of a titanium(IV)chloride burner used in titanium dioxide pigment manufacturing will be described in detail. /1/Koukkari, P.; Pajarre, R.: Introducing Mechanistic Kinetics to the Lagrangian Gibbs Energy Calculation, Computers and Chemical Engineering, Vol 30 (2006), 1189-1196. /2/Koukkari, P., Gani, R. and Pajarre, R.: Calculation of Thermochemical Properties and Processes with the Constrained Free Energy Method, to be published.
International Journal of Materials Research, Aug 8, 2013
ABSTRACT A constrained free energy model for an interfacial system of interacting layers is deriv... more ABSTRACT A constrained free energy model for an interfacial system of interacting layers is derived in the regular solution and Redlich–Kister formalisms. Composition and interfacial energies are solved using a model based on the minimisation of the total free energy of the system with a fixed interfacial area. As example cases iron–oxygen and copper– oxygen surfaces and liquid–liquid metal alloy interfaces are studied.
Chemical Engineering Science, 2016
Computer Aided Chemical Engineering, 2007
Development of robust and efficient methods for the computation of multiphase systems has long be... more Development of robust and efficient methods for the computation of multiphase systems has long been a challenge in both chemical and petroleum engineering as well as in materials science. Several techniques have been developed, particularly those which apply the Gibbs free energy minimization. In addition to calculation of global equilibrium problems, practical process simulation would benefit from algorithms, where reaction
The SGTE Casebook, 2008
ABSTRACT Based on some original thoughts by J.W.Gibbs a refined method for the introduction of ki... more ABSTRACT Based on some original thoughts by J.W.Gibbs a refined method for the introduction of kinetic controls into complex equilibrium calculations has been devised. The new method avoids problems affecting the entropy of mixing in solution phases that originate from the use of simple image components which have been applied earlier. The method is explained in detail and successful applications are discussed.
Computer Aided Chemical Engineering, 2008
Computation of chemical equilibria in multiphase systems by Gibbs free energy minimization under ... more Computation of chemical equilibria in multiphase systems by Gibbs free energy minimization under constraints set by the material balance has increasing interest in many application fields, including materials technology, metallurgy and chemical engineering. The results are utilised in multi-phase equilibrium studies or as parts of equilibrium-based process simulation. Yet, there exist a number of practical problems where the chemical system is influenced by other constraining factors such as surface energy or electrochemical charge transport. For such systems, an extended Gibbs energy method has been applied. In the new method, the potential energy is introduced to the Gibbs energy calculation as a Legendre transformed work term divided into substance specific contributions. The additional constraint potential is then represented by a supplementary undertermined Lagrange multiplier.In addition, upper bounds on the amounts of products can be set, which then limit the maximum extents of selected spontaneous chemical reactions in terms of affinity. The range of Gibbs energy calculations can then be extended to new intricate systems. Example models based on free energy minimisation have been made e.g. for surface and interfacial systems, where the surface, interfacial or adsorbed atomic or molecular layers are modeled as separate phases. In an analogous fashion the partitioning effect of a semi-permeable membrane in a two-compartment aqueous system can be modeled. In such system the large ions, not permeable through the membrane, cause an uneven charge distribution of ionic species between the two compartments. In this case, the electrochemical potential difference between the two aqueous phases becomes calculated for the multi-component system. The calculated results are consistent with the Donnan equilibrium theory; however the multi-phase system may also include the gas phase and several precipitating phases, which extends the applicability of the new method. Finally, similar constraints can also be set to extents of reaction advancements, allowing usage of Gibbs energy calculations in dynamic reaction rate controlled systems.
Computer Aided Chemical Engineering, 2008
The multi-component Gibbs energy simulation provides an efficient tool for quantifying measured d... more The multi-component Gibbs energy simulation provides an efficient tool for quantifying measured data in complex industrial systems. The advantages of the multi-phase methods have been recognized and they are becoming widely accepted in different applications, ranging from metallurgy and mate rials processing to chemistry and energy and environmental technologies. The thermodynamic multi-phase theory provides an effective method to support industrial
Proceedings of the Extraction and Processing Division Symposium on Pyrometallurgy in Honor of David G.C. Robertson, 2014
Chemical Engineering & Technology, 2015
This chapter contains sections titled: Introduction ChemSheet Model of the Flash smelter On-Line ... more This chapter contains sections titled: Introduction ChemSheet Model of the Flash smelter On-Line Model for the XSTRATA Nickel Sudbury Smelter Conclusion
Advanced Gibbs Energy Methods for Functional Materials and Processes. ChemSheet 1999-2009. Koukka... more Advanced Gibbs Energy Methods for Functional Materials and Processes. ChemSheet 1999-2009. Koukkari, Pertti (ed.). VTT Tiedotteita - Research Notes 2506, 65 - 75 This paper presents a nearly ten years history of multiphase modelling of pH and calcium chemistry in neutral papermaking. Initially the multiphase modelling was focused on pulp acidification and pH buffering concepts, and the unit operation models were used to define the dosages of acidification chemicals and buffering aids at certain stages of the process. Multiphase chemistry calculation can be appended to process simulation, thus enabling the monitoring of chemistry of large-scale processes. Recently a pioneering chemistry simulation of a process integrate consisting of two paper machine lines with both mechanical and deinked feed stocks was performed. In this integrate difficulties were often experienced when the dosage of bleaching chemicals was increased while maintaining the high brightness target of the paper produ...
Development of robust and efficient methods for the computation of multi-phase systems has long b... more Development of robust and efficient methods for the computation of multi-phase systems has long been a challenge in both chemical and petroleum engineering as well as in materials science. Several techniques have been developed, particularly those which apply the Gibbs free energy minimization. In addition to calculation of global equilibrium problems, practical simulation of multi-phase chemical reactors would benefit from such multiphase algorithms, where reaction rates are taken into account. In the present work, the method of Lagrange multipliers has been used to incorporate such additional constraints to the minimization problem, which then allow reaction rate models to be included in the Gibbsian multi-component calculation /1, 2/. The extension of the conservation matrix brings about the possibility to include reaction kinetic restrictions to control the extents of chemical reactions in terms of their affinity. A generic algorithm which combines the Gibbs energy of the contro...
Models based on free energy minimisation have been made for surface and interfacial systems, wher... more Models based on free energy minimisation have been made for surface and interfacial systems, where the surface, interfacial or adsorbed atomic or molecular layers are modelled as separate phases. Gibbs-Duhem compatible activity coefficients for the surface and interfacial layers are estimated based on known bulk thermodynamics and geometric and other considerations. The models allow the estimation of the surface energies and compositions [1] of mixtures based on pure component and bulk thermodynamic data and interfacial energies based on bulk thermodynamic values. In an analogous fashion the partitioning effect of a semi-permeable membrane in a two-compartment aqueous system can be modelled. In such system the large ions, not permeable through the membrane, cause an uneven charge distribution of ionic species between the two compartments. In this case, the electrochemical potential difference between the two aqueous phases becomes calculated for the multi-component system. The calcu...
The application of thermodynamics in biology and biochemistry has recently gained increasing inte... more The application of thermodynamics in biology and biochemistry has recently gained increasing interest due to the general trend where substitutes for petrochemicals and entirely new, sustainable means of production are being sought. Biochemical pathways involved in biological production steps can be modified by metabolic engineering. The methodical improvement of these systems requires detailed analysis of the underlying reaction networks. While tedious and often costly experimental work is required to evaluate the molecular mechanisms of reactions and their kinetic parameters, advanced thermodynamic methods provide an alternative approach to look for the most promising pathways [1]. Transformed Gibbs energies are Gibbs energies for a standard state close to the real conditions of the system at interest. Solute concentrations within cells cannot currently be determined accurately enough for normal thermodynamic modeling. The regular method of dealing with these kinds of situations in...
Computers Chemical Engineering, Jul 1, 2011
Modeling rate-controlled chemically reactive systems in biocatalysis, fuel combustion, material s... more Modeling rate-controlled chemically reactive systems in biocatalysis, fuel combustion, material science, and chemical process engineering involves the quantification and exploitation of interactions between many chemical species. These dynamic chemical systems, having relatively few limiting reactions, can be conceived as a series of snapshots where reactions have fixed extents but otherwise idle. Since the reactions affect the stoichiometric matrix of the internal constraints, such constrained equilibrium states cannot be defined in terms of conventional atomic mass balances.A systematic method for obtaining generalized equilibrium constraints for reaction mechanisms of arbitrary complexity is presented. Reaction matrices are converted into entity conservation matrices using row operations. The simultaneously introduced virtual components enable Gibbs energy calculations for complex reaction schemes including organic systems and enzyme-catalyzed biochemical transformations having multiple limiting reactions. Classical Gibbs energy minimization, which would otherwise readily model phase transformations and solvent interactions, is thereby made accessible to these emerging application fields.
Journal of Solution Chemistry, Jan 7, 2002
The ion exchange processes, which occur when two compartments of aqueous solutions separated by a... more The ion exchange processes, which occur when two compartments of aqueous solutions separated by a semi-permeable interface are placed in aqueous electrolyte solutions, were modeled by using the multi-phase Gibbs energy minimization method. The Gibbs energy minimization method was applied for the ion exchange system consisting of pulp fibers and the surrounding aqueous bulk solution, where the anionic acid groups inside the fibers cause an uneven distribution of ionic species between the solution within the fiber walls and the solution external to the fibers. The method was tested with four cation concentrations, which are naturally present in the fibers and whose partitioning between the fiber phase and the external solution phase has been described earlier. Though the Donnan distribution constant is not explicitly calculated in the Gibbs energy minimization model, the results are consistent with the Donnan equilibrium theory. With the Gibbs energy minimization multi-phase model the formation of solid precipitates can also be calculated.
ABSTRACT Models based on free energy minimisation have been made for surface and interfacial syst... more ABSTRACT Models based on free energy minimisation have been made for surface and interfacial systems, where the surface, interfacial or adsorbed atomic or molecular layers are modelled as separate phases. Gibbs-Duhem compatible activity coefficients for the surface and interfacial layers are estimated based on known bulk thermodynamics and geometric and other considerations. The models allow the estimation of the surface energies and compositions [1] of mixtures based on pure component and bulk thermodynamic data and interfacial energies based on bulk thermodynamic values. In an analogous fashion the partitioning effect of a semi-permeable membrane in a two-compartment aqueous system can be modelled. In such system the large ions, not permeable through the membrane, cause an uneven charge distribution of ionic species between the two compartments. In this case, the electrochemical potential difference between the two aqueous phases becomes calculated for the multi-component system. The calculated results are consistent with the Donnan equilibrium theory; however the multi-phase system may also include the gas phase and several precipitating phases, which extends the applicability of the new method [2]. The interfacial models are solvable in a single equilibrium calculation by using a traditional Gibbs energy minimising program. Various example cases and applications in industrial practice will be presented. References: [1] R. Pajarre, P. Koukkari, T. Tanaka, Y. Lee: Calphad, 30, (2006) 196-200. [2] R. Pajarre, P. Koukkari, E. Rsnen: Journal of Molecular Liquids, 125 (2006), 58-61.
ABSTRACT Development of robust and efficient methods for the computation of multi-phase systems h... more ABSTRACT Development of robust and efficient methods for the computation of multi-phase systems has long been a challenge in both chemical and petroleum engineering as well as in materials science. Several techniques have been developed, particularly those which apply the Gibbs free energy minimization. In addition to calculation of global equilibrium problems, practical simulation of multi-phase chemical reactors would benefit from such multiphase algorithms, where reaction rates are taken into account. In the present work, the method of Lagrange multipliers has been used to incorporate such additional constraints to the minimization problem, which then allow reaction rate models to be included in the Gibbsian multi-component calculation /1, 2/. The extension of the conservation matrix brings about the possibility to include reaction kinetic restrictions to control the extents of chemical reactions in terms of their affinity. A generic algorithm which combines the Gibbs energy of the control volume system with the salient heat and mass transfer and reaction rates has been developed. The method has been used for several scale-up studies of complex chemical reactors with simultaneous chemical reactions and phase changes. The model has been validated with both thermodynamically consistent data and with practical plant measurements. An industrial case example of a titanium(IV)chloride burner used in titanium dioxide pigment manufacturing will be described in detail. /1/Koukkari, P.; Pajarre, R.: Introducing Mechanistic Kinetics to the Lagrangian Gibbs Energy Calculation, Computers and Chemical Engineering, Vol 30 (2006), 1189-1196. /2/Koukkari, P., Gani, R. and Pajarre, R.: Calculation of Thermochemical Properties and Processes with the Constrained Free Energy Method, to be published.
International Journal of Materials Research, Aug 8, 2013
ABSTRACT A constrained free energy model for an interfacial system of interacting layers is deriv... more ABSTRACT A constrained free energy model for an interfacial system of interacting layers is derived in the regular solution and Redlich–Kister formalisms. Composition and interfacial energies are solved using a model based on the minimisation of the total free energy of the system with a fixed interfacial area. As example cases iron–oxygen and copper– oxygen surfaces and liquid–liquid metal alloy interfaces are studied.
Chemical Engineering Science, 2016
Computer Aided Chemical Engineering, 2007
Development of robust and efficient methods for the computation of multiphase systems has long be... more Development of robust and efficient methods for the computation of multiphase systems has long been a challenge in both chemical and petroleum engineering as well as in materials science. Several techniques have been developed, particularly those which apply the Gibbs free energy minimization. In addition to calculation of global equilibrium problems, practical process simulation would benefit from algorithms, where reaction
The SGTE Casebook, 2008
ABSTRACT Based on some original thoughts by J.W.Gibbs a refined method for the introduction of ki... more ABSTRACT Based on some original thoughts by J.W.Gibbs a refined method for the introduction of kinetic controls into complex equilibrium calculations has been devised. The new method avoids problems affecting the entropy of mixing in solution phases that originate from the use of simple image components which have been applied earlier. The method is explained in detail and successful applications are discussed.
Computer Aided Chemical Engineering, 2008
Computation of chemical equilibria in multiphase systems by Gibbs free energy minimization under ... more Computation of chemical equilibria in multiphase systems by Gibbs free energy minimization under constraints set by the material balance has increasing interest in many application fields, including materials technology, metallurgy and chemical engineering. The results are utilised in multi-phase equilibrium studies or as parts of equilibrium-based process simulation. Yet, there exist a number of practical problems where the chemical system is influenced by other constraining factors such as surface energy or electrochemical charge transport. For such systems, an extended Gibbs energy method has been applied. In the new method, the potential energy is introduced to the Gibbs energy calculation as a Legendre transformed work term divided into substance specific contributions. The additional constraint potential is then represented by a supplementary undertermined Lagrange multiplier.In addition, upper bounds on the amounts of products can be set, which then limit the maximum extents of selected spontaneous chemical reactions in terms of affinity. The range of Gibbs energy calculations can then be extended to new intricate systems. Example models based on free energy minimisation have been made e.g. for surface and interfacial systems, where the surface, interfacial or adsorbed atomic or molecular layers are modeled as separate phases. In an analogous fashion the partitioning effect of a semi-permeable membrane in a two-compartment aqueous system can be modeled. In such system the large ions, not permeable through the membrane, cause an uneven charge distribution of ionic species between the two compartments. In this case, the electrochemical potential difference between the two aqueous phases becomes calculated for the multi-component system. The calculated results are consistent with the Donnan equilibrium theory; however the multi-phase system may also include the gas phase and several precipitating phases, which extends the applicability of the new method. Finally, similar constraints can also be set to extents of reaction advancements, allowing usage of Gibbs energy calculations in dynamic reaction rate controlled systems.
Computer Aided Chemical Engineering, 2008
The multi-component Gibbs energy simulation provides an efficient tool for quantifying measured d... more The multi-component Gibbs energy simulation provides an efficient tool for quantifying measured data in complex industrial systems. The advantages of the multi-phase methods have been recognized and they are becoming widely accepted in different applications, ranging from metallurgy and mate rials processing to chemistry and energy and environmental technologies. The thermodynamic multi-phase theory provides an effective method to support industrial
Proceedings of the Extraction and Processing Division Symposium on Pyrometallurgy in Honor of David G.C. Robertson, 2014
Chemical Engineering & Technology, 2015
This chapter contains sections titled: Introduction ChemSheet Model of the Flash smelter On-Line ... more This chapter contains sections titled: Introduction ChemSheet Model of the Flash smelter On-Line Model for the XSTRATA Nickel Sudbury Smelter Conclusion
Advanced Gibbs Energy Methods for Functional Materials and Processes. ChemSheet 1999-2009. Koukka... more Advanced Gibbs Energy Methods for Functional Materials and Processes. ChemSheet 1999-2009. Koukkari, Pertti (ed.). VTT Tiedotteita - Research Notes 2506, 65 - 75 This paper presents a nearly ten years history of multiphase modelling of pH and calcium chemistry in neutral papermaking. Initially the multiphase modelling was focused on pulp acidification and pH buffering concepts, and the unit operation models were used to define the dosages of acidification chemicals and buffering aids at certain stages of the process. Multiphase chemistry calculation can be appended to process simulation, thus enabling the monitoring of chemistry of large-scale processes. Recently a pioneering chemistry simulation of a process integrate consisting of two paper machine lines with both mechanical and deinked feed stocks was performed. In this integrate difficulties were often experienced when the dosage of bleaching chemicals was increased while maintaining the high brightness target of the paper produ...
Development of robust and efficient methods for the computation of multi-phase systems has long b... more Development of robust and efficient methods for the computation of multi-phase systems has long been a challenge in both chemical and petroleum engineering as well as in materials science. Several techniques have been developed, particularly those which apply the Gibbs free energy minimization. In addition to calculation of global equilibrium problems, practical simulation of multi-phase chemical reactors would benefit from such multiphase algorithms, where reaction rates are taken into account. In the present work, the method of Lagrange multipliers has been used to incorporate such additional constraints to the minimization problem, which then allow reaction rate models to be included in the Gibbsian multi-component calculation /1, 2/. The extension of the conservation matrix brings about the possibility to include reaction kinetic restrictions to control the extents of chemical reactions in terms of their affinity. A generic algorithm which combines the Gibbs energy of the contro...
Models based on free energy minimisation have been made for surface and interfacial systems, wher... more Models based on free energy minimisation have been made for surface and interfacial systems, where the surface, interfacial or adsorbed atomic or molecular layers are modelled as separate phases. Gibbs-Duhem compatible activity coefficients for the surface and interfacial layers are estimated based on known bulk thermodynamics and geometric and other considerations. The models allow the estimation of the surface energies and compositions [1] of mixtures based on pure component and bulk thermodynamic data and interfacial energies based on bulk thermodynamic values. In an analogous fashion the partitioning effect of a semi-permeable membrane in a two-compartment aqueous system can be modelled. In such system the large ions, not permeable through the membrane, cause an uneven charge distribution of ionic species between the two compartments. In this case, the electrochemical potential difference between the two aqueous phases becomes calculated for the multi-component system. The calcu...
The application of thermodynamics in biology and biochemistry has recently gained increasing inte... more The application of thermodynamics in biology and biochemistry has recently gained increasing interest due to the general trend where substitutes for petrochemicals and entirely new, sustainable means of production are being sought. Biochemical pathways involved in biological production steps can be modified by metabolic engineering. The methodical improvement of these systems requires detailed analysis of the underlying reaction networks. While tedious and often costly experimental work is required to evaluate the molecular mechanisms of reactions and their kinetic parameters, advanced thermodynamic methods provide an alternative approach to look for the most promising pathways [1]. Transformed Gibbs energies are Gibbs energies for a standard state close to the real conditions of the system at interest. Solute concentrations within cells cannot currently be determined accurately enough for normal thermodynamic modeling. The regular method of dealing with these kinds of situations in...