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This paper demonstrates that the two excess Gibbs free energy G E models with temperature-dependent parameters in the modified Huron—Vidal first-order (MHV1) mixing rule allow the Peng—Robinson equation of state modified by Stryjek and Vera (PRSV) to be used for calculation of vapor—liquid equilibria over wide ranges of temperature and pressure. Good results are obtained for strongly non-ideal...
The sieve plate electrochemical reactor is a unit for enabling electrochemical reaction of gaseous species in the liquid phase. The reaction can occur either directly at the surface of the electrodes or indirectly with electrochemical mediators generated in situ. A sieve plate absorber is used for the gas-to-liquid mass transfer and, on appropriate stages, stacks of electrodes are supported on the...
A general recycle compensator, applicable to multivariable plants, is derived. For the single-variable case, the internal model control method is used to design robust controllers for the compensated plant leading to an overall better system than for the case of the uncompensated plant while, for the multivariable case, diagonal proportional plus integral controllers ensuring performance robustness...
Protein refolding is a key operation in many bioprocesses utilizing Escherichia coli. Most laboratory studies into refolding are conducted in batch systems at “infinite” dilution to avoid the formation of aggregates. This policy will be grossly suboptimal if adopted for scale-up. The impact of refolding policy on dimensionless annual operating cost for a simplified kinetic scheme is therefore investigated...
l-carnitine is a fine chemical with pharmaceutical, nutritional and animal food applications. Thus, the product purification forms an essential part of the production process. Consequently, process optimization of biotransformation and downstream processing should be done in an integral way. There are several options for the process design of the biotransformation, e.g. chemostat with cell recycling,...
The inversion of sucrose solution was studied in a packed bed of strongly acidic cation exchange resins in order to determine the values of the reaction rate constant, effective diffusivity and distribution coefficients for 20, 30 and 40 wt.% solution concentration. Typical values of specific rate constant for 30 wt.% sucrose solution varied from 0.0115 to 0.7391 min −1 in the temperature...
Ash (S.N. Ash, P. Ray and B.V. Detta, AIChE J., 31 (1985) 821; S.N. Ash, Chem. Eng. J., 48 (1992) 183) has proposed a correlation for calculating the binary parameters of the Wilson g E model by using only pure-component parameters: solubility parameters, molar liquid volumes, relative van der Waals volumes and surfaces, critical properties, acentric factors and dipole moments. To evaluate...
A moving window neural network was applied for dynamic modelling and on-line estimation of consumed sugar, cell mass, and product concentration in l-lysine fed-batch culture. The organisms were auxotrophic mutants for l-homoserine and were resistant to S-(2-aminoethyl)-l-cysteine. The reducing sugar concentration was calculated on line by using the estimated consumed sugar concentration and was maintained...
An equivalence between the Nernst—Planck approach, which takes into account the diffusive and eléctrical contributions for intraparticle mass transfer, and Fick's law, which considers only the diffusive contribution, is developed in this paper. This equivalence leads to the determination of a “corrected” diffusivity that enables the simulation of ion-exchange processes with the Fick approach. The...
Convective—diffusive mass transport coupled with a wall reaction in a planar Couette flow has been investigated. The system is isothermal and it features a first-order chemical reaction at the (upper) moving wall (or interface) combined with axial convective transport and lateral diffusion. The mathematical model defines a two-point boundary value problem in the lateral direction and an initial value...
An attempt was made to immobilize Mucor miehei lipase on ion exchange resins and other supports. Indion 850, a styrene-divinyl benzene polymer resin, proved to be the best among the supports tested. The procedure for immobilization is simple adsorption of the soluble enzyme from dilute aqueous solution onto the resin beads. The immobilized version was found to have 1.4 times higher activity compared...
Optimal regulatory control of an autoinductive recombinant culture in a fed-batch reactor is considered. End point optimization results in a three-stage process: biomass growth, inducer synthesis and product synthesis. It is shown that in the last stage the substrate concentration should be maintained constant. This is achieved using an input—output linearizing controller accompanied by a novel non-linear...
Forced intraparticle convection in a finite cylinder porous catalyst particle is studied. An analytical solution for steady state, simultaneous diffusion, convection and reaction is obtained and the effect of intraparticle convection on the catalyst performance, i.e. its effectiveness factor, is analysed. The relationship for the augmented intraparticle effective diffusivity and an equivalence ratio...
The temperature of points inside a cylindrical packed bed of silica-gel grains is measured under steady-state and transient radial heat flow conditions, for different pressures and water contents of the silica. The stationary results are used to calculate the thermal conductivity of the silica packed beds. The transient results are used to find the thermal diffusivity of the beds using a numerical...
In this paper experimental data on the heat transfer performance of a cylindrical vessel filled with liquid that is mixed using a single vibrating multihole plate are reported. A continuous liquid flow is maintained through the vessel and a Nusselt number heat transfer correlation derived for the system operating under a range of vibration conditions.
A model has been developed which predicts the performance of a batch ultrafiltration. By using the relationship for flux decline proposed by Merin and Cheryan in 1990, an analytical solution is presented. The proposed model includes the initial volume, feed solution concentrations, processing time, retention, membrane area and flux across the membrane. The model predictions are compared with experimental...
The temperature of points inside a cylindrical packed bed of silica-gel grains is measured under steady-state and transient radial heat flow conditions, for different pressures and water contents of the silica. The stationary results are used to calculate the thermal conductivity of the silica packed beds. The transient results are used to find the thermal diffusivity of the beds using a numerical...
Forced intraparticle convection in a finite cylinder porous catalyst particle is studied. An analytical solution for steady state, simultaneous diffusion, convection and reaction is obtained and the effect of intraparticle convection on the catalyst performance, i.e. its effectiveness factor, is analysed. The relationship for the augmented intraparticle effective diffusivity and an equivalence ratio...
Optimal regulatory control of an autoinductive recombinant culture in a fed-batch reactor is considered. End point optimization results in a three-stage process: biomass growth, inducer synthesis and product synthesis. It is shown that in the last stage the substrate concentration should be maintained constant. This is achieved using an input-output linearizing controller accompanied by a novel non-linear...
Large-scale liquid and gas flow patterns were measured in a 0.5-m diameter column dumped with 25- and 50-mm plastic Pall rings and 38-mm ceramic Intalox saddles. Liquid gas velocity and profiles measured for these packings were shown as a function of the initial distribution of the liquid and gas, packed height and liquid and gas flow rates. There was an emphasis in the experiments to study the development...
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