Modelling Solid Processes
Modelling Coal Drying
In this simulation you will simulate a coal drying process.
You will:
• Define nonconventional solid components.
•
• Change the global stream class.
Specify physical properties for nonconventional solid components.
•
Specify streams with nonconventional solid components.
•
•
Modify component attributes in a unit operation block.
Analyse the results.
The process flow diagram and operating conditions for this simulation are shown in the following
figure. A wet coal stream and a nitrogen stream are fed to a drier. There are two products from the
drier: a stream of dried coal and a stream of moist nitrogen.
Temp = 77 F
Pres
14.7 PSI
EXHAUST
Coal Flow = 10000 lb/hr
Water Content = 25 wt%
DRIER
WET COAL
Isobaric
Adiabatic
FLASH2
NITROGEN
Temp = 270 F
Pres 14.7 PSI
DRY COAL
Mass Flow = 50000 lb/hr
Mole Fraction N2 = 0.999
Mole Fraction O2 = 0.001
Water Content = 10 wt%
Click New on the Start Using Aspen Plus window.
The New dialog box appears. Use this dialog box to specify the template for the new run. With
the template, Aspen Plus automatically sets various defaults appropriate to your application.
1. Under Installed Templates in the panel on the left side of the New dialog box,
click Solids, then click the Solids with English Units template.
1 Information for unit sets, property method, etc. that were pre-defined in the template is shown
on the right side, in the Preview field.
A New
Blank and Recent
Solids
My Templates...
Installed Templates
A+
Solids with
Solids with
Air Separation
English Units
Metric Units
Chemical Processes
Electrolytes
Gas Processing
Metallurgy
Pharmaceutical
Polymers
Refinery
Solids
-Preview
Solids Simulation with English Units:
F, psi, lb/hr, lbmol/hr, Btu/hr, cuft/hr.
Property Method: None
Flow basis for input: Mass
2. Click Create to apply this template.
It takes a few seconds for Aspen Plus to apply these options.
Save the file now as Solid1.
Create
Cancel
The Components - Specifications | Selection sheet is used to enter the components present in
the simulation. The components in this simulation are H₂O, N2, O2, and coal.
1. In the first four Component ID fields, enter H2O, N2, O2, and COAL.
Because H2O, N2, and O2 are present in the databanks, WATER, NITROGEN, and OXYGEN
appear in the Component name field. Aspen Plus does not recognize COAL. Coal is actually
a mixture of different compounds, but for this simulation it will be treated as a single
component.
By default, Aspen Plus assumes all components are of the type Conventional, indicating that
they participate in phase equilibrium calculations. However, in this simulation, coal will be
modeled as a nonconventional solid.
2. From the COAL Type field, click
and select Nonconventional.
The Components - Specifications | Selection sheet is now complete:
2 Selection
Petroleum
Nonconventional
Enterprise Database
Info
Select components:
Component ID
Type
Component name
Alias
H20
Conventional
WATER
H20
N2
Conventional
NITROGEN
N2
02
Conventional
OXYGEN
02
COAL
Nonconventional
Find
Elec Wizard
User Defined
Reorder
Review
3. From the Navigation Pane, select Methods | Specifications.
The Methods - Specifications | Global sheet appears.
Defining Properties
The Methods - Specifications | Global sheet is used to select the thermodynamic methods used to
calculate properties such as K-values, enthalpy, and density. Property methods in Aspen Plus are
categorized into various process types.
Because the physical property methods for solid components are the same for all property methods,
select a property method based on the conventional components in the simulation.
The IDEAL property method (Ideal gas and Raoult's Law, as the prompt indicates) is a good choice for
this simulation, since the process involves the conventional components H2O, N2, and O2, at low
pressure.
In the Base method field, click and select IDEAL.
✔ Global
Flowsheet Sections
Referenced
Information
-Property methods & options
Method filter:
Base method:
COMMON
IDEAL
Method name:
IDEAL
Methods assistant...
Henry components:
-Petroleum calculation options
Free-water method: STEAM-TA
Water solubility:
3
Electrolyte calculation options
Chemistry ID:
Use true components
Modify
Vapor EOS:
Data set:
Liquid gamma:
ESIG
1
GMIDL
Data set:
1
Liquid molar enthalpy:
HLMX82
Liquid molar volume:
Heat of mixing
VLMX01
Click Next to continue.
Poynting correction
Use liquid reference state enthalpy
3
K K K K K K The Methods - NC Props | Property Methods sheet appears.
Specifying Nonconventional Solid Physical Property Models
The Methods - NC Props | Property Methods sheet is used to specify the models used to
calculate the nonconventional solid properties. Because nonconventional components are
heterogeneous solids that do not participate in chemical or phase equilibrium, the only physical
properties that are calculated for nonconventional components are enthalpy and density.
In this simulation, use the HCOALGEN and the DCOALIGT models to calculate the enthalpy and
density of coal.
1. In the Model name field for Enthalpy, click and select HCOALGEN.
The component attributes PROXANAL, ULTANAL, and SULFANAL are automatically
included in the Required component attributes field for COAL when you select
HCOALGEN. Also, four Option Codes fields with values of 1 appear.
Aspen Plus uses component attributes to represent nonconventional components in terms of
a set of identifiable constituents needed to calculate physical properties. HCOALGEN uses
the proximate analysis, ultimate analysis, and sulfur analysis to calculate the enthalpy of coal.
The Option Codes fields define how the HCOALGEN model calculates the heat of
combustion, the standard heat of formation, the heat capacity, and the enthalpy basis for coal.
2. In the Model name field for Density, click and select DCOALIGT.
The Property Methods sheet is complete:
Property Methods
Information
Component:
COAL
-Property models for nonconventional components
Model name
Option codes
Enthalpy HCOALGEN
1
1
1
1
Density DCOALIGT
Required component attributes
PROXANAL
ULTANAL
SULFANAL
3. Click to continue.
4 The Required Properties Input Complete dialog box appears:
A* Required Properties Input Complete
Next step:
Run Property Analysis / Setup
Modify required property specifications
Enter property parameters
Enter experimental data
Go to Simulation environment
OK
Cancel
Correct representation of physical properties is an essential component of process modeling.
For many simulations, the only physical property specification that you must provide is the
selection of a property method. The Required Properties Input Complete dialog box shows
that the Aspen Plus physical property system has many optional capabilities that you can use
to increase the accuracy of physical property calculations.
4. Select Go to Simulation environment and click OK to continue.
Drawing the Graphical Simulation Flowsheet
In this simulation, begin building the process flowsheet. Since you will enter your own
block and stream IDs, turn off the automatic naming of blocks and streams, which provide
these IDs automatically.
1. From the ribbon, click File. Click Options.
The Options dialog box appears.
2. Select Flowsheet from the panel on the left side of the dialog box.
3. Clear the Automatically assign block name with prefix and Automatically
assign stream name with prefix check boxes under Stream and unit operation
labels.
Flowsheet Display Options
Simulation
Temperature: %.Of
Label
Prop-Set
Format
Properties Basis
Files
Pressure:
%.Of
Custom1
་
%.2f
Flowsheet
Vapor fraction:
%.2f
Custom2
▾
%.2f
Plots
Upward Compatibility
Mole flow rate: %.Of
Custom3
%.2f
Advanced
Startup
Mass flow rate: %.Of
Custom4
%.2f
Volume flow rate: %.Of
Custom5
%.2f
Heat/Work:
%.Of
Customб
%.2f
Status display on Process Flowsheet window
Show error
Show warning
Show inactive
Stream and unit operation labels
Automatically assign block name with prefix:
Display block name
Automatically assign stream name with prefix: S
Display stream name
Label Font...
Placement antione
8 pt. Arial
OK
Cancel
Apply
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