91成人短视频

Session Chairs:

• Onkar Manjrekar, Abbvie Inc.
• Jennifer Larimer, The Dow 91成人短视频 Company
• Richard Grenville, Philadelphia Mixing Solutions

Session Description:

Mixing is considered a critically important unit operation in many industrial processes.   Mixing in multiphase systems often adds additional complexity over homogeneous mixing, especially when scaling processes. This session will explore mixing in both solid-liquid and immiscible liquid-liquid multiphase systems and highlight considerations for scale up.

*All session and speaker information is subject to change pending finalization

Schedule:

Abstracts:

Optimal Mixing in Agitated Extraction Columns

Donald Glatz & Brendan Cross, Koch Modular Process Systems

Liquid-liquid extraction columns are designed to increase the interfacial surface area between the two immiscible phases so that the solute to be removed can be efficiently transferred between the phases.  The efficiency of an extraction column is generally optimized when the disperse phase droplets are as small as possible and the contact time is maximized.  In agitated extraction columns, increased agitation results in higher efficiency (theoretical stages per unit height of the column) up to a certain point.  If the agitation speed is too high, this can result in lower performance due to back-mixing of the continuous phase or flooding where the disperse phase stops flowing counter currently to the continuous phase.  When designing an agitated column the goal is to find the optimal speed which will produce the best possible efficiency.  However, the type of mixing also plays an important role for the best design of an agitated extraction column.  Typically there are two methods for providing mixing in agitated column; rotating type impellers, of which there are many different types and reciprocating plates.  Experience has demonstrated that the rotating internals work the best for systems that require a high amount of agitation, typically high interfacial tension and/or high density difference between the phases.  Conversely, reciprocating internals have been found to be the better choice for systems with low interfacial tension and/or low density difference between the phases.  The focus of this presentation will be to focus on these two types of mixing and how each can be used to provide the best column design for different types of systems.

Time-accurate Modeling of Multicomponent Fluid Mechanical Systems using GPUs

John A. Thomas, M-Star CFD

The behavior of multicomponent fluid mechanical systems, including liquid/solid, liquid/liquid, and liquid/gas mixtures, is governed by flow physics that operate over a range of length and time scales.  At the smallest scales, process outcomes are governed by Kolmogorov-sized eddies and particle relaxation times.   At the largest scales, system performance is governed by tank residence times, blend times, and the dimensions of the system.  These smallest and largest scales are coupled by a continuous cascade of fluid motion and eddy break-up. 

The fidelity of a computational model is correlated to the range of length/time scales it can capture simultaneously. Although models for predicting the mean flow field have existed for decades, their inability to capture transient eddy structures limits their applicability to multicomponent process modeling.  In this presentation, we show how modern CFD algorithms operating on graphics processing units (GPUs) can enable real-time multicomponent flow modeling in industrial systems.  Following an overview of the underlying theory and implementation, we validate this approach by comparing real-time model predictions to measured data obtained from particle suspension systems and gasified bioreactors.

Scale-up of Mixing Processes in Solid-Liquid Systems

Jason J. Giacomelli, Philadelphia Mixing Solutions

The design and scale-up of processes in which solids are handled has historically been problematical (see for example Merrow, Chem. Innov., 2000 or Bell, Powder Tech., 2005).  Plants in which solids are a raw material, intermediate and / or product often fail to reach design capacity within 12 months of plant start-up which plants which process only fluids often meet the design capacity and, in some cases, exceed it.

Two aspects of agitator design in solids processing will be reviewed in this presentation:

1. Determining the minimum agitator speed required to ensure that all particles are in motion.  This is the optimum operating condition for mass transfer between the particles and the liquid phase.

The results of recent experiments examining the effect of solids concentration on this impeller speed will  be briefly reviewed.  Also, the minimum velocity for slurry transport in pipelines is a similar design criterion in that all particles must be in motion, suspended from the pipe floor, and design rules for mixing and pipe flow will be compared.

2. Control of particle size and distribution during precipitation reactions.  Generation of large particles with a mono-modal distribution is desirable since this optimizes the performance of downstream washing and separation equipment.  Poor mixing promotes primary nucleation and formation of fines.

Experiments that can be carried out at bench and pilot scale will be described along with their interpretation in terms of well-developed mixing models.