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Jump Start: Solids Process Modeling for ExperiencedAspen Plus® Users

A Brief Tutorial (and supplement to training and online documentation)

Jennifer Dyment, Product Marketing, Aspen Technology, Inc.Claus Reimers, Product Management, Aspen Technology, Inc.Ajay Lakshmanan, Product Management, Aspen Technology, Inc.Matthias Pogodda, Software Development, Aspen Technology, Inc.Wilfried Mofor, Product Management, Aspen Technology, Inc.


Jump Start: Solids Process Modeling for Experienced Aspen Plus® Users

Table of ContentsIntroduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

First Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Specifying Solid Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Specifying Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Specifying Stream Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Particle Size Distribution Meshes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Unit Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

The Model Palette . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Dryer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Spray Dryer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Crystallizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Granulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Crusher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Fluidized Bed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Conveying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Results Summaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Activated Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17



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IntroductionSolids process modeling with Aspen Plus provides an integrated solution for simulating processes containing solids. With

the tools provided, it is easy to characterize and model these components and obtain reliable results based on the world’s

most comprehensive property database and proven simulation technology. This functionality bridges the gap between

process engineering and particle science by providing the tools to seamlessly integrate rigorous models for solid streams

and unit operations with typical fluid process models. Now users can simulate processes that contain both fluids and

solids in the same simulation environment, allowing accelerated production of consistent, conceptual designs.

This document serves as a simple “getting started guide” for users who are experienced with Aspen Plus (but not

necessarily solids process modeling). We will take you through the most common progression of how a process designer

creates a simulation and implements solid components and unit operations. This is not meant to be used as a stand-alone

reference document. We recommend that a range of other resources be called upon to give the new user a comprehensive

view of how to use solids modeling in Aspen Plus. These may include:

• AspenTech support website (support.aspentech.com) – contains a wide range of knowledge base items and provides

answers to frequently asked questions

• AspenTech self-guided examples are available on aspenONE® Exchange or can be accessed by going here:

http://www.aspentech.com/October_2013_solids_modeling_demo_AT/

• AspenTech courseware available in on-line and in-person versions — provides formal training on process modeling

• AspenTech business consultants

This document covers solids modeling in Aspen Plus. This guide assumes that the user has Aspen Plus V8.4 or higher

installed on their computer. Most features were introduced with V8.0, such as particle size distribution characterization

and a majority of the unit operations. See Table 1 below for more information.

Table 1: Solids related features highlighted for the Aspen V8.0, V8.2, and V8.4 releases

Version Date of Release Features

Aspen Plus V8.0 December 2012

• Integration of 25 SolidSim unit operations

• PSD characterization

• Solids-related results representation

Aspen Plus V8.2 May 2013

• Economics for solids processing (Activated Economics)

• Total of 38 SolidSim unit operations integrated

• Enhanced PSD definition and results representation

Aspen Plus V8.4 November 2013

• Conceptual models

• Spray dryer unit model

• Reactions in fluidized bed unit model



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First StepsThis section talks about the first steps you must take to include solid components in your model. It does not cover every

step in creating a flow sheet.

Specifying Solid Components

When you specify a component, its default type is Conventional. However, in order to model solid components you must

change this to Solid (Figure 1).

Figure 1: Specify a stream as solid

Specifying Properties

Since the properties for solids are different than the conventional properties for fluids, it might be necessary to manually

manage those that apply to your process. In the Navigation Pane, select the “Methods” folder, then “Parameters.” Then

click “New” and select the type of parameter that you want to specify in the pane that follows (Figure 2).

Figure 2: New property specification

Next, fill in the matrix of parameters and components as desired. Hover over any of the parameters in the dropdown list to

see what the variables stand for (Figure 3).



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Figure 3: Specify properties for desired compounds

Specifying Stream Class

Once all of the property specifications are complete, you can move on to flow sheet specifications in the Simulation

Environment. In the “Setup – Specifications” form you must select an appropriate stream class. To determine which is

best, hover over the different choices on the dropdown menu to see suggestions (Figure 4). Typically, MIXCIPSD is a good

choice when conventional solids are present with a particle size distribution.

Tips and Tricks: You can always manually specify properties for components. This is especially

helpful when working with compounds that are not well documented (such as different grades

of coal).


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Figure 4: Specify stream class

Particle Size Distribution MeshesA common way of characterizing a solid stream is by particle size distribution (PSD), which describes the relative quantity

of particles of varying sizes in a stream (generally a powder or granular material). A PSD can be expressed as either a list

of values or a mathematical function.

To define a PSD in Aspen Plus, you must first create a mesh (array of particle size classes), which characterizes a

particular PSD. In the Navigation Pane, go to the “Setup” folder, then “Solids,” and select “PSD.” In order to define the PSD

mesh, you either select a pre-defined mesh type (e.g. equidistant, geometric, or logarithmic) and enter the necessary

parameters, or you define your mesh manually (e.g. selection user) as tabular data. For the later option, you can also copy

and paste from the spreadsheet tools (e.g. MS Excel). Fill out the required inputs and select “Create PSD Mesh” (Figure 5).

While the first mesh you define (named “PSD” by default) is used for the simulation, additional meshes can be created for

streams that have different particle size distributions. To create additional meshes, go to “Solids” and select the PSD Mesh

tab. Then choose “New…” (Figure 6). It is also possible to create new meshes on the stream data input (see ‘streams’). For

more information, visit the self-guided example for setting up a particle size distribution in Aspen Plus available on

aspenONE Exchange.

Figure 5: Create PSD mesh



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Figure 6: Generate additional PSD meshes

Unit OperationsTable 2 shows a list of all of the solids unit operations available in Aspen Plus. This section only focuses on getting started

with five of the most common blocks. To find more detail on any of these or to learn about the unit operations not

discussed here, check out the Computer Based Training (CBT) Courses available on the AspenTech support website.

Table 2: Solids unit operations in Aspen Plus

Unit Operation Block Name Tab

Classifier Classifier Solids

Crusher Crusher Solids

Crystallizer Crystallizer Solids

Convective Dryer and Spray Dryer Dryer Solids

Granulator/Agglomerator Granulator Solids

Multi-stage Solids Waster andCounter Current Decanter CCD Solids

Screen Screen Solids

Single Stage Solids Washer Swash Solids

Centrifuge Cfuge Solids Separators

Cyclone Cyclone Solids Separators

Electrostatic Precipitator ESP Solids Separators

Fabric Filter FabFl Solids Separators

Filter Filter Solids Separators

Hydrocyclone HyCyc Solids Separators

Venturi Scrubber Vscrub Solids Separators

Fluidized Bed FluidBed Solids

Solids Conveying Pipe & Pipeline Pressure Changers


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The Model Palette

To open the Model Palette, click the Model Palette button in the Show group on the View tab (Figure 7). There are

two tabs on the palette that contain solid unit operations, the Solids tab and the Solids Separators tab (Figure 8).

Figure 7: The Model Palette button

Figure 8: The solids model palettes – Solids (top), Solids Separators (middle), and Pressure Changers (bottom)

Dryer

There are two ways to model a dryer in Aspen Plus: shortcut dryer and convective dryer. There is also an option to

model a Spray Dryer in Aspen Plus. Please see the section below. In order to switch types, use the dropdown menu on the

Specifications tab for the dryer (Figure 9). The shortcut dryer allows you to model the unit operation with a minimum of

information and can be used for any type of dryer. The convective model requires additional material streams for input and

output of a drying gas (Figure 10) and requires more information. This is the more rigorous model.

Figure 9: Select dryer type



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Figure 10: Material streams for convective dryer model - red indicates a required stream, while blue indicates an optional stream

There are a number of self-guided examples pertaining to modeling dryers in Aspen Plus available on aspenONE

Exchange. Examples include a belt dryer, fluidized bed dryer, mill dryer, flash dryer, and a batch dryer.

Spray Dryer

The Spray Dryer model is found in the Dryer block and allows you to model a wide range of industrial spray

dryers. The model is based on single droplet drying kinetics and does not consider the coalescence of droplets or the

agglomeration of particles. The model considers multiple aspects of the spray dryer including atomization, droplet

movement, drying, and particle formulation.

Under the atomization tab (Figure 11), users have the ability to specify the type of model used for the droplet size

distribution, including a built-in atomization model.

Figure 11: Atomization can be specified with the atomization tab of the Spray Dryer unit operation

The droplet movement is considered as downward fall and the equation of motion is derived from a force balance with

ignores lift. The model considers the first (constant drying rate) and the second (falling drying rate) period. The second

drying rate is described by use of a normalized drying curve. The normalized drying curve can be defined as tabular data

or by use of a drying curve function. Particle formulation starts after the moisture content of the particle reaches the

critical moisture content. Particle formulation can either be described with a solid particle model or with a porous particle

model.


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Figure 12: After critical moisture is met, the particle can either shrink in diameter to a solid particle or maintain a constant diameter and becomea porous particle

There is self-guided example pertaining to modeling a spray dryer in Aspen Plus available on aspenONE Exchange.

Crystallizer

The crystallization block allows you to model steady-state crystallization. To do so, you can choose between

three different calculation methods: solubility, chemistry, and user subroutine (Figure 13).

Figure 13: The crystallizer form: input calculation method and operating mode

Each method requires a different set of input parameters, allowing you to choose how to calculate based on available

property and operating information.

Wet ParticleDroplet

Solid Particle

Porous Particle

ConstDiameter

Ideal Shrinkage

Ideal Shrinkage

1st Drying Stage 2nd Drying Stage

Xcrit



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Granulator

The granulator block allows you to model the growth of particles by either granulation or agglomeration. In

addition to this, the block has a shortcut model that allows you to define the outlet PSD (conceptual/short-cut model).

Table 3 summarizes the minimum stream requirements for each of these options. If you include a gas stream, your model

becomes a fluidized bed granulator and you cannot use either of the shortcut methods.

Table 3: Granulator methods and their associated stream requirements

If you select particle growth by granulation, there are two available calculation models: mixed and plug flow. In mixed, all

parameters are independent of position, whereas in plug flow, size is dependent on position. Both models assume:

• Steady state process

• All particles are spherical

• The suspension and particles are homogeneous

• The solid concentration of the suspension is constant

In the case of a fluidized bed granulator, solids may be entrained by the fluidizing gas. To consider this, you must add a

fluidization gas stream to the block and specify the cross-sectional area of the granulator and the ‘separation sharpness’

(Figure 14).

Figure 14: Specify elutriation parameters for a fluidized bed granulator


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There are self-guided examples for modeling granulation and agglomeration in Aspen Plus available on aspenONE

Exchange.

Crusher

You can model a variety of crushers and mills with the crusher block. Aspen Plus provides three methods to

determine the outlet PSD:

• Use an equipment model (e.g. hammer mill)

• Determine outlet PSD from a power and distribution function

• Define outlet PSD by use of a distribution function or tabular data

If you want to use an equipment model, you must choose the equipment type and provide the necessary geometry and

operating parameters (Figure 15).

Figure 15: Specify crusher type

For a first estimate, it might be sufficient to specify the outlet size distribution or determine it based on the comminution

power. If you wish to use a comminution power, you must provide a Bond work index on the Grindability tab and specify if

you wish to use Bond’s, Rittinger’s, or Kick’s law to calculate it (Figure 16). Table 4 summarizes the appropriate situations

for each law.

Table 4: Determine the appropriate comminution law



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Figure 16: Specify comminution law and bond work index for a crusher

You can define the outlet PSD by using either distribution functions or by using tabular data.

Figure 17: Specify outlet PSD using tabular data for a crusher

There is a self-guided example for modeling crushing and screen potassium chloride in Aspen Plus available on aspenONE

Exchange.


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Screen

Aspen Plus allows you to model multi-deck screens. When creating a screen block, you must include outlet

overflow (coarse material) and underflow (fine material) streams. You also have the option of adding up to nine midsize

streams. Once you have added the appropriate number of material streams. You must fill out the stream specification

matrix. Aspen Plus will automatically provide the appropriate number of screen decks to accommodate the desired

number of outlet streams (Figure 18).

Figure 18: Screen specification matrix

The classification of the particles on each screen deck is described by a selection function (e.g. Plitt, Rogers, Molerus etc.).

In addition, you can also specify outlet fines or calculate the fish-hook effect using the Whiten model, by filling out the

appropriate parameters on the matrix.

Fluidized Bed

The fluidized bed model in Aspen Plus allows you to model reactions, fluid mechanics, and the interaction of

both—as well as the entrainment of particles. It also considers the geometry of the vessel, any additional gas supply, and

the impact of heat exchangers on the bed temperature and fluid mechanics. With these features, you can determine the

minimum fluidization velocity, the transport disengagement height, and the entrainment of solids from the bed. The

fluidized bed model (Figure 19) considers two zones in the vessel, the bottom zone or dense bed and the freeboard,

allowing you to determine the bubble related profiles in the bottom zone and the entrainment of solids in the freeboard.

Figure 19: To the left is a schematic of the two zones within the fluidized bed and to the right is the corresponding solids holdup as a function ofreactor height



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Chemical reactions can be considered in the fluidized bed including changes in the PSD due to reactions. The reactions are

defined in the reactions form for the simulation and can be further described with solids information by clicking the solids

button (Figure 20).

There are self-guided examples for modeling fluidization including a fluidized bed reactor in Aspen Plus available on

aspenONE Exchange.

Conveying

Pneumatic conveying is used to transport powdered and granular solid material over short and long

distances. This can be described by using the pipe or pipeline blocks that can be found on the Pressure Changers tab in

the model palette of Aspen Plus. Both the pipe and the pipeline block allow you to model dilute and dense phase

conveying of granular solids. In general, dilute phase has a lower solids loading and a lower pressure drop but the velocity

at which the solids travel through the pipe needs to be relatively fast to avoid saltation or clogging. With dense phase

conveying, solids are transported in dunes or slugs at low velocities and high pressure.

Conveying lines can be operated in pressure or suction mode, depending on the positioning of the blower which is

responsible for the pressure change (Figure 21).

Figure 21: Users can see the pressure, elevation, and velocity as a function of the pipeline length

Figure 20: For reactions involving solid phases, a solids form,accessed in the reactions tab, allows the user to specify whichphases the reactants are in

There are self-guided

examples for

modeling

transportation of

solids by pneumatic

conveying in Aspen

Plus available on

aspenONE Exchange.


14


AnalysisResults Summaries

Two quick ways to obtain information about your model are the model and stream summaries. The model summary,

accessible from the Model Summary button in the Summary group on the Home tab, (Figure 22), provides information on

the input parameters and operating conditions for every block in your process. It is organized by unit operation, therefore

all of the blocks of a common type are summarized on the same tab (Figure 23).

Figure 22: The Model Summary button

Figure 23: The model summary form

The stream summary displays all of the information available on each of the streams in the model. It is accessible from the

Stream Summary button in the Summary group on the Home tab. When viewing the summary you have the option of

viewing all streams, or restricting your view to selected streams. To choose, select the appropriate option from the

“Display” dropdown in the upper left corner (Figure 24).

Tips and Tricks: Blue parameters in the model summary are user inputs and can be changed

directly in the form.



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Figure 24: The stream summary – Choose to see either all streams or selected streams

To find information on streams that contain solid materials, it is important to scroll down the summary matrix until you

reach the item that says “*** ALL PHASES ***.” Complete data for streams containing solids will only be available below

this row (Figure 25).

Figure 25: Scroll down to *** ALL PHASES *** to find data on streams containing solid materials

Additionally, you can filter what type of data is shown in the stream results by selecting a category from the “Format”

dropdown menu (next to the “Display” dropdown). To view the particle size distribution of each stream in tabular form,

select “SOLIDS.”


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Plots

There are a variety of plots that you can create to visually analyze your data (PSD, Separation Efficiency, etc.). To generate

a plot, open the form for a unit operation or material stream and select the appropriate button from the Plot group on the

Home Tab. Note that you may have to scroll down to reach the desired button. You can also view all the available plot

types by clicking the down arrow below the scroll bar (Figure 26). To determine what type of information is displayed on

each plot, hover over the button.

Figure 26: Select the desired type of plot

Bear in mind, different types of unit operations and material streams are conducive to generating different kinds of plots.

For example, you cannot generate PSD plots unless solids are present.

Activated Economics

While developing a design, you can utilize activated economics to explore different configurations and options to choose

the most cost effective design. With activate analysis, you can explore priliminary cost analysis with the click of a button

and explore the costs associated with each step by hovering over the unit after running activated economics (Figure 27).

Figure 27: Economic Analysis was done for the crushing section of this process to determine a first estimate of the cost of the project

Note: You can only generate plots if you have run the simulation and obtained results.

Tips and Tricks: Data from the matrices provided by the model and stream summaries can

easily be highlighted and then copied and pasted directly into Microsoft Excel.



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Additional ResourcesFor further information on solids process modeling with Aspen Plus please consult:

Public Website:

http://www.aspentech.com/

Support Website:

The support website provides an extensive and growing knowledge base as well as Computer Based Training (CBT)

Courses

http://support.aspentech.com/webteamasp/My/FrameDef.asp?/webteamasp/My/product.asp?id1=4&id2=''&id3=all

Example Files:

Click the Examples button on the Get Started tab when you open Aspen Plus to see some out of the box simulations.

Using aspenONE Exchange or the support website, you can also access self-guided examples, which include both an

example simulation and a step-by-step guide to work through the example. These self-guided examples can also be

accessed here: http://www.aspentech.com/October_2013_solids_modeling_demo_AT/.


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About AspenTech

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