Quantitative Analysis of Residence Time Distribution in Kenics Static Mixer

2012 ◽  
Vol 499 ◽  
pp. 198-202 ◽  
Author(s):  
Dan Jin ◽  
Hai Ling Fu ◽  
Jian Hua Wu ◽  
Dan Sun
Keyword(s):  
Quantitative Analysis ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Plug Flow ◽  
Axial Direction ◽  
Static Mixer ◽  
Mixing Quality ◽  
Experimental Approaches ◽  
The Mean

The residence time distribution in Kenics static mixer is investigated using experimental approaches. Experimentally, RTD measure in SK with pulse tracer technology was used to characterize flow and mixing quality. The effect of velocity on the RTD was investigated for all sections. The results show that the flow in SK mixer tends to the plug flow along the axial direction when the velocity increases. The quantization analysis, the effect of factors on the mean residence time, is done by using the power function considering the numbers of mixer element, diameter, element aspect radio, and velocity. The validity of this function is testified by other experiments.

Liquid phase residence time distribution for gas–liquid flow in Kenics static mixer

2008 ◽  
Vol 47 (12) ◽  
pp. 2275-2280 ◽  
Author(s):  
Tirupati Reddy Keshav ◽  
P. Somaraju ◽  
K. Kalyan ◽  
A.K. Saroha ◽  
K.D.P. Nigam
Keyword(s):  
Liquid Phase ◽  
Residence Time ◽  
Liquid Flow ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Static Mixer ◽  
Gas Liquid Flow

scholarly journals Modeling Residence Time Distribution (RTD) Behavior in a Packed-Bed Electrochemical Reactor (PBER)

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Sananth H. Menon ◽  
G. Madhu ◽  
Jojo Mathew
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Flow Model ◽  
Plug Flow ◽  
Flow Characteristics ◽  
Theoretical Models ◽  
Packed Bed ◽  
Electrochemical Reactor ◽  
Tracer Studies

This paper focuses on understanding the electrolyte flow characteristics in a typical packed-bed electrochemical reactor using Residence Time Distribution (RTD) studies. RTD behavior was critically analyzed using tracer studies at various flow rates, initially under nonelectrolyzing conditions. Validation of these results using available theoretical models was carried out. Significant disparity in RTD curves under electrolyzing conditions was examined and details are recorded. Finally, a suitable mathematical model (Modified Dispersed Plug Flow Model (MDPFM)) was developed for validating these results under electrolyzing conditions.

scholarly journals Explicit Residence Time Distribution of a Generalised Cascade of Continuous Stirred Tank Reactors for a Description of Short Recirculation Time (Bypassing)

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 615 ◽  
Author(s):  
Peter Toson ◽  
Pankaj Doshi ◽  
Dalibor Jajcevic
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Flow Reactor ◽  
Plug Flow ◽  
Stirred Tank ◽  
Stirred Tank Reactors ◽  
Delayed Impulse ◽  
In Series ◽  
Back Mixing

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.

The Mixing Characteristics and Residence Time Distribution of Cut Tobacco Particles in Drum Mixer

2011 ◽  
Vol 396-398 ◽  
pp. 297-301
Author(s):  
Wen Kui Zhu ◽  
Dong Liu ◽  
Jin Song Du
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Plug Flow ◽  
Processing System ◽  
Rotating Speed ◽  
Drum Mixer ◽  
Method Effects ◽  
Residence Time Distributions ◽  
Cut Tobacco

Residence time distributions were determined for the continuous processing of cut tobacco in the rotary drum by introducing expanded cut tobacco tracers to the inlet of the processing system using the negative step change method. Effects of rotating speed of the rotary cylinder and solids flow rate on the mixing homogenization and residence time distribution (RTD) of experiment materials was investigated. PER-CSTR series model and multistage CSTR model were used to fit the experimental results. The result shows mixing homogenization increased significantly with the increasing feeding rate of cut tobacco and decreasing drum rotating speed. PER-CSTR series model is more suitable to describe the RTD characteristics of flow materials in drum. The axis movement of cut tobacco along the drum is approximate to the plug-flow.

Enhanced Convective Mixing and Residence Time Distribution in Advanced Micromixers

2012 ◽  
Author(s):  
Maximilian Fischer ◽  
Norbert Kockmann
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Mixing Performance ◽  
Rapid Mixing ◽  
Dean Vortices ◽  
Convective Mixing ◽  
Mixing Quality

Homogeneous mixing of liquids in microchannels is well known and characterized for simple channel geometries, such as Y- or T-shaped mixers. Also meandering mixing channels, in which Dean vortices are generated, are often employed to achieve rapid mixing of liquids. A CFD study was performed to increase the mixing performance in the contacting and first mixing element. Dean vortices in the inlet channels increase the mixing quality for Re numbers in the range from 20 to 200 together with S-shaped mixing elements. Mixing quality is significantly increased by a factor of 2 to more than 5 compared to a T-shaped mixer. The residence time distribution is a further important parameter, which is investigated in this contribution.

scholarly journals Derivation of a Multiparameter Gamma Model for Analyzing the Residence-Time Distribution Function for Nonideal Flow Systems as an Alternative to the Advection-Dispersion Equation

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Irucka Embry ◽  
Victor Roland ◽  
Oluropo Agbaje ◽  
Valetta Watson ◽  
Marquan Martin ◽  
...  
Keyword(s):  
Dispersion Equation ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Flow Reactor ◽  
Plug Flow ◽  
Absolute Deviation ◽  
Suitable Alternative ◽  
Advection Dispersion ◽  
Flow Systems

A new residence-time distribution (RTD) function has been developed and applied to quantitative dye studies as an alternative to the traditional advection-dispersion equation (AdDE). The new method is based on a jointly combined four-parameter gamma probability density function (PDF). The gamma residence-time distribution (RTD) function and its first and second moments are derived from the individual two-parameter gamma distributions of randomly distributed variables, tracer travel distance, and linear velocity, which are based on their relationship with time. The gamma RTD function was used on a steady-state, nonideal system modeled as a plug-flow reactor (PFR) in the laboratory to validate the effectiveness of the model. The normalized forms of the gamma RTD and the advection-dispersion equation RTD were compared with the normalized tracer RTD. The normalized gamma RTD had a lower mean-absolute deviation (MAD) (0.16) than the normalized form of the advection-dispersion equation (0.26) when compared to the normalized tracer RTD. The gamma RTD function is tied back to the actual physical site due to its randomly distributed variables. The results validate using the gamma RTD as a suitable alternative to the advection-dispersion equation for quantitative tracer studies of non-ideal flow systems.

scholarly journals Self-similarity of fluid residence time statistics in a turbulent round jet

2017 ◽  
Vol 823 ◽  
pp. 1-25 ◽  
Author(s):  
Dong-hyuk Shin ◽  
R. D. Sandberg ◽  
E. S. Richardson
Keyword(s):  
Reynolds Number ◽  
Probability Density ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Mass Fraction ◽  
The Self ◽  
Similar Profile ◽  
Self Similar ◽  
The Mean

Fluid residence time is a key concept in the understanding and design of chemically reacting flows. In order to investigate how turbulent mixing affects the residence time distribution within a flow, this study examines statistics of fluid residence time from a direct numerical simulation (DNS) of a statistically stationary turbulent round jet with a jet Reynolds number of 7290. The residence time distribution in the flow is characterised by solving transport equations for the residence time of the jet fluid and for the jet fluid mass fraction. The product of the jet fluid residence time and the jet fluid mass fraction, referred to as the mass-weighted stream age, gives a quantity that has stationary statistics in the turbulent jet. Based on the observation that the statistics of the mass fraction and velocity are self-similar downstream of an initial development region, the transport equation for the jet fluid residence time is used to derive a model describing a self-similar profile for the mean of the mass-weighted stream age. The self-similar profile predicted is dependent on, but different from, the self-similar profiles for the mass fraction and the axial velocity. The DNS data confirm that the first four moments and the shape of the one-point probability density function of mass-weighted stream age are indeed self-similar, and that the model derived for the mean mass-weighted stream-age profile provides a useful approximation. Using the self-similar form of the moments and probability density functions presented it is therefore possible to estimate the local residence time distribution in a wide range of practical situations in which fluid is introduced by a high-Reynolds-number jet of fluid.

scholarly journals Determination of the residence-time distribution in industrial dryer for the production of recycled polyester

2020 ◽  
pp. 47-47
Author(s):  
Felipe Zauli da Silva ◽  
Izabella Bastos ◽  
Rafael Perna ◽  
Sergio Villalba Morales
Keyword(s):  
Intrinsic Viscosity ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Industrial Processes ◽  
Polyester Fibers ◽  
Pulse Type ◽  
The Mean

The study proposes the evaluation of the residence-time distribution (RTD) in-situ in an industrial dryer for the production of recycled polyester fibers (PES) from colorless polyethylene terephthalate (PET) flakes without interruption of the production. A disturbance of the pulse type was employed, in which the tracer (blue PET flakes) had previously been crystalized and its concentration was obtained according to the time at the dryer outlet. Additionally, analyses of intrinsic viscosity and crystallization percentage of the PET flakes (colorless and blue) and PES intrinsic viscosity and color force were performed. By RTD, the mean residence time (322.8 min), the variance (1305.4 min2), the standard deviation (36.1 min) and the relative error (1.5%) were obtained when compared to the theoretical residence time, indicating the absence of preferred paths or flake agglomerates in the equipment. Finally, the characterization demonstrated that there was no alteration in the parameters of product quality during RTD evaluation, confirming the potential of application of this methodology for diagnoses of continuous industrial processes.

Dispersion Number Studies in ChemicalMechanical Planarization

2003 ◽  
Vol 767 ◽  
Author(s):  
Ara Philipossian ◽  
Erin Mitchell
Keyword(s):  
Fluid Dynamics ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Dispersion Model ◽  
Flow Behavior ◽  
Plug Flow ◽  
Operating Conditions ◽  
The Coefficient Of Friction ◽  
Dispersion Number

AbstractThis study explores aspects of the fluid dynamics of CMP processes. The residence time distribution of slurry under the wafer is experimentally determined and used to calculate the Dispersion Number (Δ) of the fluid in the wafer-pad region based on a dispersion model for non-ideal reactors. Furthermore, lubrication theory is used to explain flow behaviors at various operating conditions. Results indicate that at low wafer pressure and high relative pad-wafer velocity, the slurry exhibits nearly ideal plug flow behavior. As pressure increases and velocity decreases, flow begins to deviate from ideality and the slurry becomes increasingly more mixed beneath the wafer. These phenomena are confirmed to be the result of variable slurry film thicknesses between the pad and the wafer, as measured by changes in the coefficient of friction (COF) in the pad-wafer interface.

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