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W artykule przedstawiono analizę zagadnienia przenoszenia skali na przykładzie jednego z typów krystalizatora powszechnie stosowanego w aplikacjach przemysłowych. Zdefiniowano istotny parametr procesowym, mający duży wpływ na powtarzalność technologii. Określono wymagania z punktu widzenia kinetyki procesu podczas przenoszenia skali oraz, biorąc pod uwagę najczęściej stosowaną procedurę, przeanalizowano możliwości i ograniczenia tego sposobu.
The paper deals with scale-up problems. The issue is discussed in the light of draft tube magma crystallizer, commonly used in crystallization processes from solution. Authors defined the parameters mainly affecting the crystallization and product requirements during scale-up on one hand and on another consider, what can be done when the traditional procedure is applied.
A scaled-up SRCCC apparatus equipped with a 40-L column was constructed on the basis of separations of crude broccoli seed extract and crude radish seed extract using a conventional SRCCC instrument. Scaled-up separation of 500 g of crude broccoli seed extract with n -butanol-acetonitrile-10% (NH 4 ) 2 SO 4 aqueous solution 1:0.5:2 (υ/υ) as solvent system yielded 61.5 g glucoraphanin product of purity 91.2%. Separation of 500 g crude radish seed extract with the same solvents in the ratio 0.5:1:2 (υ/υ) afforded 26.7 g glucoraphenin product of purity 94.5%. Recovery of glucoraphanin and glucoraphenin from the crude extracts was 98.3 and 98.9%, respectively. The results demonstrated that this SRCCC technology is useful for separation of glucosinolates from plant extracts.
In the paper investigation results dealing with the suspension preparation in a mixer with the disc agitator are presented. Critical conditions for suspending of solid particles in the liquid phase were determined. The influence of particle concentration on the power input was analysed. The results obtained were elaborated using the Froude number in a form of the dimensionless correlation describing the influence of process parameters on suspension, formation.
Content available remote Simulation of the gluconic acid production in the internal loop airlift bioreactor
Airlift reactors have found potential application in biotechnology and chemical industries due to their simple construction and less performance costs compared with mechanically stirred tanks. However, an accurate description of their performance and "a priori" design are still difficult. This work deals with mathematical modelling of the fermentation process in an internal loop airlift reactor (IALR). To verify the simulation results, fermentation of gluconic acid by the strain Aspergillus niger has been chosen as a model system. Fermentation was carried out in three laboratory lALRs (each one with different scale of the reactor volume: 12, 40 and 200 litres). The parameters of the model, e.g. parameters of the kinetic model, mass transfer coefficients, circulation velocities and gas hold-ups were estimated by employing correlations available in the literature or independent experiments using model media. In the present paper the influence of different performance conditions (gas inlet flow rate, oxygen concentration in the feed gas, initial concentration of glucose) on the reactor behaviour is investigated. The results of simulations and experiments are in a sufficient agreement. The developed and tested model can be used as a very useful tool for process design, optimization and scale-up.
Content available remote Design and scale-up of airlift bioreactors
In the presented paper the role of airlift bioreactor size and geometric design, and composition of fermentation broth on the liquid circulation velocity, gas hold-up and the oxygen mass transfer rate are investigated. Three laboratory internal loop airlift reactors (lALRs) with a different scale of total reactor volumes: 12, 40 and 200 litres were used. As a model system, transformation of glucose to gluconic acid using Aspergillus ni-ger strains was chosen. A comparison of hydrodynamic characteristics of lALRs with water - air system and three-phase real fermentation media was made.
Exploration of several process parameters (temperature, solvent composition, amount of concentrated HCl, scale-up factor) supported by an analysis of the reaction response surfaces fitted to the experimental data allowed to determine convenient and amenable for considerable scale-up route of dehydration of exo-hydroxymethyl group in androstane skeleton affording exemestane in high yield.
Content available remote The Application of silo centrifuge testing
Common problems of industrial silo design can be solved with the use of the Jenike method. The Jenike method is an established procedure to investigate the critical outlet dimensions of a silo and the flow profile. However, in some cases the Jenike method is assumed to lead to overdesign, especially when silo design is calculated for highly dispersed bulk solids in the nano range or if the bulk solid contains moisture. Another way to determine the critical outlet dimension of a silo is a model test. We then have to consider the boundary conditions, i.e. the particle size, and a possible size reduction of the model silo, which is only possible in a centrifugal field using cohesive bulk solids. In this work, results of experiments in a silo centrifuge regarding scale-up are presented. The experiments have been performed to investigate the critical outlet dimension for a silo for very fine and moist bulk solids.
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