Particle Residence Time Distribution of Collection Zone in Packed Flotation Column

2013 ◽  
Vol 781-784 ◽  
pp. 2195-2200
Author(s):  
Li Zhang ◽  
Yi Gang Ding ◽  
Jun Ji ◽  
Chang Yan Yang ◽  
Yuan Xin Wu

In order to make a further understanding of flow pattern and back mixing in the flotation process, the study about particle residence time distribution of collection zone in a packed column has been designed. The pulse tracer method was applied and the particle tracers were the mineral gangue in special size class. The residence time distribution curves of our experiment data shows that there are particle back mixings which were caused by fluid flow and geometry factors in the column. The tank-in-series model has a better fitting to the particle residence time distribution in the column according the comparison research between the tank-in-series model and axial dispersion model. The operation parameters have different effects on the particle residence time distribution according to our experimental study.

Author(s):  
R. Mythilishri ◽  
V. P. Kamalakannan ◽  
R. Saravanathamizhan ◽  
N. Balasubramanian

Abstract Decolorization of dye waste water is performed using a Tubular Electrochemical Reactor. Stainless steel and oxide coated on titanium mesh acts as the cathode and anode respectively. Experiments were conducted in batch with recirculation mode. The effect of operating parameters such as current density, initial dye concentration, flow rate and supporting electrolyte concentration on decolorization of Acid red dye has been studied and the results were analysed using Taguchi Method. A Residence Time Distribution (RTD) study has been conducted in a Tubular electro chemical reactor and an axial dispersion model has been developed to determine percentage decolorization. The model results are compared with experimental results and it was found that the model satisfactorily matches with the experimental results with high correlation coefficient.


2010 ◽  
Author(s):  
Sugiharto ◽  
Zaki Su’ud ◽  
Rizal Kurniadi ◽  
Abdul Waris ◽  
Zainal Abidin ◽  
...  

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 207 ◽  
Author(s):  
Jens Wesholowski ◽  
Andreas Berghaus ◽  
Markus Thommes

Over recent years Twin-Screw-Extrusion (TSE) has been established as a platform technology for pharmaceutical manufacturing. Compared to other continuous operation, one of the major benefits of this method is the combination of several unit operations within one apparatus. Several of these are linked to the Residence Time Distribution (RTD), which is typically expressed by the residence time density function. One relevant aspect for pharmaceutical processes is the mixing capacity, which is represented by the width of this distribution. In the frame of this study the influence of the mass flow, the temperature and the screw-barrel clearance were investigated for a constant barrel load (specific feed load, SFL). While the total mass flow as well as the external screw diameter affected the mixing performance, the barrel temperature had no influence for the investigated range. The determined results were additionally evaluated with respect to a fit to the Twin-Dispersion-Model (TDM). This model is based on the superimposition of two mixing functions. The correlations between varied process parameters and the obtained characteristic model parameters proved this general physical view on extrusion.


Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 615 ◽  
Author(s):  
Peter Toson ◽  
Pankaj Doshi ◽  
Dalibor Jajcevic

The tanks-in-series model (TIS) is a popular model to describe the residence time distribution (RTD) of non-ideal continuously stirred tank reactors (CSTRs) with limited back-mixing. In this work, the TIS model was generalised to a cascade of n CSTRs with non-integer non-negative n. The resulting model describes non-ideal back-mixing with n > 1. However, the most interesting feature of the n-CSTR model is the ability to describe short recirculation times (bypassing) with n < 1 without the need of complex reactor networks. The n-CSTR model is the only model that connects the three fundamental RTDs occurring in reactor modelling by variation of a single shape parameter n: The unit impulse at n→0, the exponential RTD of an ideal CSTR at n = 1, and the delayed impulse of an ideal plug flow reactor at n→∞. The n-CSTR model can be used as a stand-alone model or as part of a reactor network. The bypassing material fraction for the regime n < 1 was analysed. Finally, a Fourier analysis of the n-CSTR was performed to predict the ability of a unit operation to filter out upstream fluctuations and to model the response to upstream set point changes.


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