Axial dispersion in single pellet-string columns with non-porous packing

2004 ◽  
Vol 59 (6) ◽  
pp. 1301-1307 ◽  
Author(s):  
Olga Šolcova ◽  
Petr Schneider
1996 ◽  
Vol 61 (6) ◽  
pp. 844-855 ◽  
Author(s):  
Olga Šolcová ◽  
Petr Schneider

It was shown that the sampling loop, detector and connecting elements in the chromatographic set-up for determination of transport parameters by the dynamic method significantly influence the response peaks from columns packed with porous or nonporous particles. A method, based on the use of convolution theorem, was developed which can take these effects into account. The applicability of this method was demonstrated on the case of axial dispersion in a single-pellet-string column (SPSR) packed with nonporous particles. It is possible to handle also responses from columns packed with porous particles by a similar procedure.


Author(s):  
Gülşen Doğu ◽  
Timur Doğu

Abstract Moment technique has been extensively used for the evaluation of the rate and equilibrium parameters in chemical reactors and also in adsorption vessels, for about five decades. Adsorption and reaction rate parameters, as well as axial dispersion constants, effective diffusivities within porous catalysts and heat and mass transfer coefficients were shown to be effectively evaluated by analyzing the moments of the response peaks, which could be obtained from pulse-response experiments performed in a reaction/adsorption vessel. A detailed review of chromatographic processes, involving moment analysis of adsorption equilibrium and rate constants in fixed beds, dynamic analysis of batch adsorbers, moment analysis of fluidized bed, slurry and trickle bed reactors are reported in this manuscript. Applications of the single-pellet moment technique, which was developed for the effective investigation of intrapellet rate and equilibrium processes, by eliminating the contributions of axial dispersion and external transport parameters, are comprehensively discussed. Recent studies for the analysis of reaction rate parameters using the TAP reactor approach, use of single pellet system for the investigation of catalytic and non-catalytic solid-gas reactions and extension of the moment technique to non-linear systems opened new pathways in reaction engineering research.


2005 ◽  
Vol 110 (1-3) ◽  
pp. 11-18 ◽  
Author(s):  
Olga Šolcová ◽  
Karel Soukup ◽  
Petr Schneider

1991 ◽  
Vol 56 (6) ◽  
pp. 1249-1252
Author(s):  
Marie Fialová ◽  
Ctirad Verner ◽  
Lothar Ebner

The characteristics of axial dispersion in the liquid phase were measured for two basic flow regimes in a horizontal two-phase tube reactor. The data obtained indicate that in some flow regions, axial dispersion can be quite significant.


2021 ◽  
Vol 35 (2) ◽  
pp. 1449-1464
Author(s):  
Ali Hedayati ◽  
Robert Lindgren ◽  
Nils Skoglund ◽  
Christoffer Boman ◽  
Norbert Kienzl ◽  
...  

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1236
Author(s):  
Hamid Mortazavi ◽  
Leila Pakzad

Oscillatory baffled reactors (OBRs) have attracted much attention from researchers and industries alike due to their proven advantages in mixing, scale-up, and cost-effectiveness over conventional stirred tank reactors (STRs). This study quantitatively investigated how different mixing indices describe the mixing performance of a moving baffle OBR using computational fluid dynamics (CFD). In addition, the hydrodynamic behavior of the reactor was studied, considering parameters such as the Q-criterion, shear strain rate, and velocity vector. A modification of the Q-criterion showed advantages over the original Q-criterion in determination of the vortices’ locations. The dynamic mesh tool was utilized to simulate the moving baffles through ANSYS/Fluent. The mixing indices studied were the velocity ratio, turbulent length scale, turbulent time scale, mixing time, and axial dispersion coefficient. We found that the oscillation amplitude had the most significant impact on these indices. In contrast, the oscillatory Reynolds number did not necessarily describe the mixing intensity of a system. Of the tested indices, the axial dispersion coefficient showed advantages over the other indices for quantifying the mixing performance of a moving baffle OBR.


1968 ◽  
Vol 23 (10) ◽  
pp. 1287-1291 ◽  
Author(s):  
J.R. Balder ◽  
E.E. Petersen
Keyword(s):  

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