SETTING UP A SIMULATION – OVERVIEW

There are eight basic steps involved in preparing, running, and viewing results for a process simulation in ProPlan. These steps are presented below. Please click on the links for more details.

 

Step 1 Set up a new project

Step 2 Selecting units

Step 3 Building a flowsheet

Step 4  Enter Prices for Utilities / Pooled Components

Step 5 Run simulation

Step 6  Review results

Step 7  Printing Results

Step 8  Save the model

 

These steps do not have to be performed in this order nor do all of them have to be completed for each flowsheet.  All should be considered for each project.

There are a series of Help facilities available throughout the program.  The Help command provides access to the On-line Manual, which contains comprehensive technical information.  Use of these help facilities will ease your way through the program.

ProPlan is object-oriented. Therefore, most input and editing can be done by left or right clicking the object of the operation, as well as by using the menu commands.

 

All stream and unit operations specifications (input) are accomplished using dialog boxes.  These dialog boxes are context specific and employ some combination of character fields, choice boxes and check boxes.

Major program activities are organized around the following features:

 

The Menu Bar

The Standard toolbar   

The Simulation Toolbar

The Directory Tree

Microsoft Excel

 

Step 1 Set up a new project

ProPlan keeps track of flowsheet data and the corresponding results by storing it in a file named (projectname). By default, ProPlan saves your project in the Data folder in the directory where ProPlan is installed. You can select any other parent directory for your projects.

 

To start a new job you must select the New Job function on the File menu (or click the New button on the toolbar). When this is done, you are ready to begin working in your new job and its flowsheet.

This is illustrated in the steps below.

 

 

 

Alternatively, you can perform this task by the File à New command in the File Menu

 

Step 2 Selecting units

 

To select engineering units for a flowsheet, you must select the Options from the File Menu.

 

General tab:

The fields on this tab help to document the project. This page is optional and entries on this page have no effect on the results of the simulation.

 

Optimizer tab:

If you select “Off” in the optimize field, Optimization will be suppressed and a baseline solution will be generated. If you want ProPlan to find the best set of values (Variables, Parameters) that maximize the profit, then you must enable the optimizer by selecting “On” in the Optimize field.

 

Tolerance:

The Tolerance value here indicates the minimum relative increase in the profit between successive iterations and determines convergence.  The suggested value is 0.001.     

 

Iteration:

The maximum number of iterations indicates the number of iterations performed by the optimizer before it stops if it cannot find an optimal solution.  The default value is 100.

 

Step: 

The step indicates the percent change in the variable values from the starting value to perform the initial trial. Based on the change in the Profit with the change in the variable values the optimizer then decides the direction.  The default value is 0.00001

 

Step 3 Creating a flowsheet

Creating a new flowsheet comprises of the following basic steps

 

 

Crude Distillation Unit

The CDU (Crude Distillation Unit) in ProPlan is a special block that can simulate up to ten product streams. The product yields and properties are determined based on the assay data provided in the input crude oil assays. The Parameters page allows you to define the products and enter the cut temperatures for these products.

 

Parameters: Parameters for the crude Unit are the Cut Temperatures for yield calculations. The Cut Temperature represents the final temperature for all product cuts. The Cut Temperatures of all but last cut must be specified. Minimum and Maximum temperature bounds must be provided if a cut temperature is to be varied (during optimization)

ProPlan allows you to enter the overlap/gap between adjacent products. The overlap default entry is 0 but you can override that by specifying a value between 0 and 1. In such cases, it is recommended that the adjacent cuts should differ in temperature sufficiently so that cut yields below 2% (by weight) on crude are avoided.

 

Product Names: These are the names of the product streams corresponding to the cut temperatures specified. If any of the products are not connected to downstream unit operation, then ProPlan considers that product saleable. You can input the price for any of such products in Price field adjacent to the corresponding product. Also, specify the basis for this price input (Weight / Volume)

 

Calculation Order

ProPlan generates a default calculation order on basis of the order of their creation, i.e., the first unit created on the flowsheet will be solved first; the second unit created will be solved next and so on. You have the facility to override this calculation order. To do so, click on the Calc Order button on the Main Toolbar or the Calculation Order button on the Unit Operation dialog.

 

Step 4  Enter Prices for Utilities / Pooled Components

Pricing information is required to compute profitability and optimize profits.  The Price Input form is accessed via the Prices button on the File Menu command or by clicking the ‘$ ‘button on the Simulation Toolbar.

The user must enter stream prices on a volume or weight basis. The basis (volume or weight) must be specified in the column on the right of the Pooled Components page.

Please note that, weight price must be entered for the three pooled components H2, Fuelgas and H2S and GAS.  The Vol and Wt entry specifications are ignored for the utility streams. If cost information is not entered, the price is set to zero.   The prices of the Feed and Products are entered on the Feeds and Product Blender dialog box respectively.

 

Price information must be provided for all utility and material (product and sales) streams in order to conduct accurate calculations.  The capital investment required must be entered on an Annual Percent Return on Investment basis. 

 

Step 5 Run simulation

Once you have configured the modules in your flowsheet and entered the input feed streams data, the flowsheet is configured. Now you are ready to run the simulation.

Select Run from the File Menu or click the RUN button on the Standard Toolbar.

 

ProPlan first checks for errors in data inputs. If there are critical errors in the input data, then ProPlan issues an error message and the run stops.  A comprehensive list of errors generated when ProPlan encounters invalid input can be found in the help menu.

 

Step 6  Review results

Once the simulation has been run, you can see the results of the simulation under the Reports section in the Directory Tree. This provides a comprehensive report of all the modules in the flowsheet.

 

The Summary sheet provides the economic overview of the plant by using Feed and Product rates and prices along with prices of Utilities, Capital etc.

 

For viewing the results of the modules in the flowsheet, click on the respective names in the Directory Tree. Alternatively, you can right-click on the desired module in the flowsheet to view the results for that module. The results are displayed in a tabular format and in a graphical format to facilitate quick review and assimilation of information.

 

To view the data of any stream on the flowsheet, right-click on that stream. A window, pops up.

The Module and the Type fields indicate the name and the type of the module from which this stream is originating. Under the Properties page, you will find complete information pertaining to this stream.

 

A comprehensive report for the utilities, pooled components and import streams can be found by clicking the Utilities, Pooled Components and Import Streams fields in the Directory Tree respectively.

 

ProPlan makes reporting very quick and easy by communicating with Microsoft Excel®. You can export the complete results or result of any individual unit by clicking on Export To Excel button on any window from the directory tree. ProPlan asks you for the location where you want to create the Excel file. Once this file is created, you can easily print, copy, save or e-mail the file just like any other Excel file.

 

Step 7  Printing Results

To print the flowsheet, make the flowsheet visible by clicking on the flowsheet in the Configuration / Reports area and select print from the File menu. You can also click on Print Preview option in the menu or Print Preview button on the Standard Toolbar.

 

By default, ProPlan sets the printer orientation as landscape. However, if the printer is configured such that it prints in portrait mode, ProPlan does NOT override the printer settings. To make sure that the flowsheet is printed as required, go to your printer options and configure it to print it in landscape orientation.

 

You can print the report for a particular module in a similar way. Clicking on a module under the Reports head in the Directory Tree will bring up a report for that module. This report can now be printed from the report menu. The report for this module can be printed by clicking the Print button located on the top right hand section of the dialog box.

 

Step 8  Save the model

The project can be saved to a disk using the File | Save and File | Save As from the file menu commands.  The .pro file suffix is automatically added to the file name.

RULES FOR WRITING EQUATIONS

You can modify the inbuilt equations for yields, properties and utilities consumption. The equations contain correlations to estimate the capital investment requirements and the rate of consumption of utilities. You can edit/customize the equations to reflect individual operational features. Following is a description of certain points you need to keep in mind before you start editing the equations. You can have up to a 150 equations for each unit operation. The equations in ProPlan have to be written in English Units only.

 

Please refer to the help menu for further explanation

BLENDING CORRELATIONS

The different blending correlations used by ProPlan are described below.

 

Blending by Volume

 

ProPlan calculates certain mixture properties using volume or weighted averages.  Properties calculated using this approach include SG, VABP, RON, MON, RM2, PAR, OLE, NAPH, ARO, CET, ANL, V150, V300, V400, V500, V650, and the custom user properties 1 through 8.

 

Blending by Weight

 

ProPlan calculates certain mixture properties using mass weighted averages.  Properties calculated using this approach include SUL, OXY, NIT, NI, VAN, C5I, CCR and the custom user properties 9 through 16.

 

Blending Indices

 

ProPlan calculates certain mixture properties by converting the values using blending indexes and subsequently calculating the mixture properties using weight or volume weighted averages.  The blend indices used are published in the open literature.  Some of them are listed below:

 

Property                       Index

RVP                             (V) ^1.25

Viscosity                      LN (LN (V+0.8))

Smoke Pt.                    (1/V)

Freeze Pt.                     Exp (13.333 LN ((V+460)/600))

Pour Pt.                        Exp (12.5 LN ((V+460)/600))

Flash Pt                        Exp (-16.667 LN ((V+460)/600))

 

'V’ denotes the value of the property.

UTILITIES

 

The utilities consumed by all process units in the simulation are automatically computed and reported in the output.  The consumption and production of the utilities is defined in the Equations page of each process unit.  Utilities are not listed in the input file but do require that the user provide the necessary prices.  For calculation purposes, the capital investment required for a process is treated as a utility.

 

Units of Measure

 

The units of measure used must be consistent for all Equations page and user-entered price data.  For example, if ‘Euro’ is the adopted unit of measure for currency, all Equations page must reflect correlations based on the same.

 

The unit of measure used in the simulations is GASLHV, which represents the total heat content of the utility (and is not mass specific).  For Equations page, the more convenient units are FUEL for MMBtu of liquid fuels and GASLHV for MMBtu of gas fuels.

 

List of Utilities

 

A list of the different types of utilities is presented.  The short identification (ID) is the designated term used in submodels.

 

                        ID                                Component

                        FUEL                           Fuel

                        HPSteam                      High Pressure Steam

                        MPSteam                     Medium Pressure Steam

                        LPSteam                      Low Pressure Steam

                        BFW                            Boiler Feed Water

                        CW                              Cooling Water

                        POWER                      Power

                        Chemical                      Chemicals

                        Capital                         Capital Cost

                        GasLHV                      Fuel Gas (BTU, kCal, GJ)

                        Utility1             User-defined utility

                        Utility2             User-defined utility


POOLED COMPONENTS

 

The generation or depletion of pooled components is controlled by the equations entered in the respective modules of each unit operation.  Although pooled components are not listed in the Block Input files, price information must be entered by the user.

 

Typically, process units that yield fuel gas products generate pooled components that are estimated on a weight basis and identified by the component, GAS.  The associated heat content of the stream is represented as a utility and identified by the utility, GASLHV.

 

Finally, the generation or depletion of the pooled components per unit block is presented in the output report.  For a completed simulation, GAS denotes the total pooled material through the flowsheet, while GASLHV represents the utility consumption.

 

 

List of Pooled Components

 

A list of the pooled components is presented.  ProPlan recognizes the Name of the component exactly as it appears in the following table. The same representation is to be used while referring to these components in the equations.

 

                        Name                           Component

                        H2                               Hydrogen

                        Fuelgas             Fuel Gas

                        H2S                             Hydrogen Sulfide

                        Propane                       Propane

                        Propylene                     Propylene

                        IButane                        Iso-butane

                        NButane                       Normal butane

                        Ibutene                         Iso-butylene

                        Butenes                        Mixed Butenes

 

 


OPTIMIZATION

 

ProPlan is capable of determining an optimum solution that maximizes the net profit by varying user selected process unit parameters and blender specifications.  It uses LINDO’s rigorous NLP Solver to reach the optimum solution.

 

In order to perform an optimization, switch on the radio button in the optimizer tab in the options dialog box. As with most functions, a local optimum may be reached if the underlying equations are nonlinear.  Moreover, the final solution often depends on the initial estimates used.  A solution may be verified by altering the initial estimates, which should result in the same solution.  In cases of local optima, a small increase in the parameters results in no increase in profits but a larger increase may lead to a regime of higher profit.

 

There are some points to be considered while configuring the Min/Max values for CDU’s cut temperatures.

 

 

 

 

 

DEMO MODEL

 

A fully functional demo model is provided with the setup program for new users to explore. It is placed under the Data directory in the folder where you have installed ProPlan. The name of the file is demomodel.pro Please use this model to observe the various functionalities described in the previous sections.


 

MISCELLANEOUS 

 

Standard Stream Properties

 

The list of properties available is presented here.  Additional properties may be defined by using the Options form.  Property names must be spelled verbatim for the blender input and sub models.

Properties 1 to 8 are any user-defined properties that may be calculated based on linear mixing rules by volume.  The process sub models that incorporate the properties for calculations must be consistent in the interpretation of the values.  Properties 9 to 16 are similar in function but defined for weight blending properties.

 

Certain stream properties must be defined if the simulator is to perform the block calculations.  For process submodels, if the feed properties that are required to calculate product yields (and SG) are missing, a fatal error is indicated.  Many properties have default values of zero.  This is usually true for contaminants (such as, SUL and NIT).  Other properties, such as viscosity and RON, have no default values.  Such properties must be defined for blocks whose submodels use the properties during calculations.

 

A list of properties that are supported by ProPlan is presented.  Additional properties may be defined using the General Input form.  The units of measure must be consistent with those used by the process submodels (for example, RVP may be in psia, kPa or Kg/Cm2).

 

 

Display Name                           Property Name

RATEV                                    Volume flow rate

RATEW                                   Weight flow rate

SG                                           Specific gravity

API                                          API density

VABP                                      Volume average boiling point

SUL                                         Weight percentage of Sulfur

OXY                                        Weight percentage of Oxygen

RVP                                         Reid vapor pressure

FLSH                                       Flash point

RON                                        Research Octane Number

MON                                       Motor Octane Number

RM2(R+M)/2                          If RON and MON both are provided, RM2 will be calculated automatically.

PAR                                         Volume percentage of Paraffins

OLE                                         Volume percentage of Olefins

NAPH                                     Volume percentage of Naphthenes

ARO                                        Volume percentage of Aromatics

BENZ                                      Volume percentage of Benzene

SMK                                       Smoke point

FRZ                                         Freeze point

POR                                        Pour point

CET                                         Cetane Index

ANL                                        Aniline point

CS122                                     Viscosity, CS at 122 oF

CS210                                     Viscosity, CS at 210 oF

NIT                                          Weight percentage of Nitrogen

NI                                            Nickel, ppm

VAN                                        Vanadium, ppm

C5I                                          C5 insoluble

CCR                                        Weight percentage of Conradson carbon

V150                                       Volume percentage evaporated at 150 oF

V200                                       Volume percentage evaporated at 200 oF

V300                                       Volume percentage evaporated at 350 oF

V400                                       Volume percentage evaporated at 400 oF

V500                                       Volume percentage evaporated at 500 oF

V650                                       Volume percentage evaporated at 650 oF

Properties 1 to 8                       User Defined Volume Blending Property

Properties 9 to 16                     User Defined Weight Blending Property

 

 

Default Measurement Units

 

The English units of measure are used, unless otherwise indicated. The following table indicates the default units that are used by ProPlan.

 

Property           Default Units of Measure

RateV              bbl

RateW             klb

Temp               F

Energy              MMBTU

RVP                 psiA

Currency          $

CW                  Mgal

Utilities such as LPS, HPS and BFW, are calculated always on weight basis and no separate conversion factor can be entered. The factor for Weight Conversion will be used.  Note that you cannot enter a conversion factor for POWER. Not entering a conversion factor is equivalent to entering a value of 1.0 for it.