			Home About us Contact

Liquid Reactor (liquid + reactor)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Bubble size distribution modeling in stirred gas,liquid reactors with QMOM augmented by a new correction algorithm

AICHE JOURNAL, Issue 1 2010
Miriam Petitti
Abstract Local gas hold-up and bubbles size distributions have been modeled and validated against experimental data in a stirred gas,liquid reactor, considering two different spargers. An Eulerian multifluid approach coupled with a population balance model (PBM) has been employed to describe the evolution of the bubble size distribution due to break-up and coalescence. The PBM has been solved by resorting to the quadrature method of moments, implemented through user defined functions in the commercial computational fluid dynamics code Fluent v. 6.2. To overcome divergence issues caused by moments corruption, due to numerical problems, a correction scheme for the moments has been implemented; simulation results prove that it plays a crucial role for the stability and the accuracy of the overall approach. Very good agreements between experimental data and simulations predictions are obtained, for a unique set of break-up and coalescence kinetic constants, in a wide range of operating conditions. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

Continuous process for production of hydrogenated nitrile butadiene rubber using a Kenics® KMX static mixer reactor

AICHE JOURNAL, Issue 11 2009
Chandra Mouli R. Madhuranthakam
Abstract A continuous process for hydrogenating nitrile butadiene rubber (NBR) was developed and its performance was experimentally investigated. A Kenics® KMX static mixer (SM) is used in the process as a gas,liquid reactor in which gaseous hydrogen reacts with NBR in an organic solution catalyzed by an organometallic complex such as an osmium complex catalyst. The Kenics® KMX SM was designed with 24 mixing elements with 3.81 cm diameter and arranged such that the angle between two neighboring elements is 90°. The internal structure of each element is open blade with the blades being convexly curved. The dimensions of the SM reactor are: 3.81 cm ID 80 S and 123 cm length and was operated cocurrently with vertical upflow. The NBR solutions of different concentrations (0.418 and 0.837 mol/L with respect to [CC]) were hydrogenated by using different concentrations of the osmium catalyst solution at various residence times. The reactions were conducted at a constant temperature of 138°C and at a constant pressure of 3.5 MPa. From the experimental results, it is observed that a conversion and/or degree of hydrogenation above 95% was achieved in a single pass from the designed continuous process. This is the first continuous process for HNBR production that gives conversions above 95% till date. Optimum catalyst concentration for a given mean residence time to achieve conversions above 95% were obtained. Finally, a mechanistic model for the SM reactor performance with respect to hydrogenation of NBR was proposed and validated with the obtained experimental results. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Bubble size distribution modeling in stirred gas,liquid reactors with QMOM augmented by a new correction algorithm

Binary coalescence of air bubbles in viscous liquids in presence of non-ionic surfactant

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2008
K. Giribabu
Abstract Coalescence of air bubbles is important in gas,liquid reactors and food processing operations. Bubbles can be stabilized by using non-ionic surfactants. Binary coalescence of air bubbles in ethylene glycol and aqueous glycerol solutions were studied in this work in presence of Span 80. A novel set-up was developed to study long coalescence times. Coalescence time was observed to follow broad stochastic distributions in all systems. The distributions were fitted with a stochastic model developed earlier. The surface tension of ethylene glycol and glycerol solutions was measured at various concentrations of Span 80. These data were fitted using a surface equation of state derived from the Langmuir isotherm. The effect of surfactant concentration on coalescence time was explained in terms of the surface excess of the surfactant and the repulsive force generated at the air,liquid interface. The results from this work illustrate the stochastic nature of bubble coalescence in viscous liquids. This work also demonstrates how non-ionic surfactants can stabilize bubbles in such liquids. La coalescence des bulles d'air est importante dans les réacteurs gaz-liquide et les opérations de l'industrie alimentaire. Les bulles peuvent être stabilisées en utilisant des surfactants non ioniques. La coalescence binaire de bulles d'air dans des solutions aqueuses d'éthylène glycol et de glycérol a été étudiée dans ce travail en présence de Span 80. Un nouveau montage a été mis au point pour caractériser les temps de coalescence longs. Le temps de coalescence a été observé afin de suivre les distributions de modèle stochastique dans tous les systèmes. Les distributions ont été calées à un modèle stochastique mis au point antérieurement. La tension de surface des solutions d'éthylène glycol et de glycérol a été mesurée à différentes concentrations de Span 80. Ces données ont été calées à l'aide d'une équation d'état de surface calculée à partir de l'isotherme de Langmuir. L'effet de la concentration de surfactant sur le temps de coalescence est expliqué par l'excès de surface du surfactant et la force répulsive créée à l'interface air-liquide. Les résultats de ce travail illustrent la nature stochastique de la coalescence des bulles dans les liquides visqueux. Ce travail démontre également comment les surfactants non ioniques peuvent stabiliser les bulles dans de tels liquides. [source]