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Aspen Technology

Burlington, MA

2013

Particle Size Distribution

Guide to the PSD Demo

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Definition of Particle Size Distribution (PSD)

PSD is described by Particle size classes or

intervals

(e.g. 1 2 mm)

Mass fractions within theparticle size classes

First, the particle size classes(PSD mesh) must be definedfor the simulation

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Definition of Particle Size Distribution

There are two methods for the definition of the PSD Mesh

AutomatedMesh

GenerationUser Define

Mesh

Size classes are defined as tabulartable by hand

Select one of the pre-defined meshes(equidistant, geometric, logarithmic,user-defined)

Enter the parameters for the selectedmesh including lower limit, upper limitand number of classes.

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Definition of Particle Size Distribution

After a stream has beenmade, the massfractions of the PSDshould be defined

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Definition of Particle Size Distribution

Methods for thedefinition of the massfractions

User-specified values(measured data) Copy and paste from

Microsoft Excelpossible

A distribution function:

Available: GGS, RRSB,normal, log-normal

Select function youwant to use

Enter shape and

position parameter(e.g. d63,3and n forRRSB)

Tip: You can also access the PSD mesh definition from the stream input form, by clicking the EditPSD Mesh button

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Definition of Particle Size Distribution

User guidance diagrams for PSD definition:

PSD definition using a distribution functions may require normalization due tomismatch of used particle size mesh and the distribution functionparameterization

PSD plots visualize the defined data and compares it to the theoretical curvedescribed by the selected distribution function

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Solids Characterization- PSD definition user guidance diagrams

Examples of mismatching mesh and parameterization of the

distribution function Mesh ends too early / starts too late

Mesh too coarse

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PSD definition user guidance diagrams

Open file empty mesh.bkp

Open input form for stream S1

Review defined PSD mesh

equidistant 10 classes 0-10 mm

Select populate PSD using Adistribution function

Select Normal as distributionfunction

Enter:

Standard deviation = 1 mm

D50 = 9 mm

Click Calculate

Click Yes on the openingmessage box normalize

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PSD definition user guidance diagrams

In this case the mesh ends at 10 mm but the theoretical curve goesto 13 mm mesh ends too early

Solution: Adjust the upper limit of the PSD mesh

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Adjust the PSD mesh

Click the Edit PSD Mesh button on theinput form of the stream

Enter 13 mm for the upper limit

Click the create PSD mesh button

Click the apply button

New mesh with an upper limit of 13 mmwill be generated

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Adjust the PSD mesh

In the stream inputform, click thecalculate button inthe distributionfunction section

new calculation ofmass fractions basedon updated mesh

Click Yes on theopening messagebox normalize

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Results with the adjusted the PSD mesh

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PSD definition user guidance diagrams

Now create a new distributionfunction

Select populate PSD using Adistribution function

Select Normal as distribution

function

Enter:

Standard deviation = 0.1 mm

D50 = 5.1 mm

Click Calculate

Click Yes on the openingmessage box normalize

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PSD definition user guidance diagrams

In this case the mesh is too coarse

Class width is 1 mm, but standard deviation is 0.1 mm

Solution: Adjust the number ofintervals in the PSD Mesh

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Adjust number of PSD intervals

Click the Edit PSD Mesh buttonon the input form of the stream

Enter 50 for the number of intervals

Click the create PSD mesh button

Click the apply button

New mesh will have 50 particle sizeclasses

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Adjust number of PSD intervals

In the stream inputform, click thecalculate button inthe distributionfunction section

new calculation ofmass fractions basedon updated mesh

Click Yes on theopening messagebox normalize

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Results with the adjusted the PSD mesh