Models
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SysCAD Model Documentation
A SysCAD project consists of a number of independent process units, known as models, connected by pipes or links. Each model is documented independently, with the same general description.
The SysCAD process models that have been programmed are stored in a number of different dll libraries. The user can specifies which dll libraries, and which models within these, that are required for each project in the project configuration file.
General Models
These models are used in most projects. They generally form the backbone of the project.
| Name | Description | License | Solver |
|---|---|---|---|
| Feeder-Cross Page Connector | A source or sink of material, or it can be used to connect streams on different flowsheets. | Standard | PB/Dyn |
| Pipe | Pipe or material transfer model used to connect units. This may have pressure and velocity information if used in a dynamic model. | Standard | PB/Dyn |
| Tank | A multi-purpose storage unit for material. Can contain reactions, heat exchanger, makeups or general splitter (GM) sub-models. | Standard | PB/Dyn |
| Tie | The tie can be used to join two or more streams, or to split a stream into a number of streams. It may have up to 20 inputs and 20 outputs. It may also contain reactions, makeups, vapour-liquid equilibrium (VLE) and/or general splitter (GM) sub-models. | Standard | PB/Dyn |
Energy Transfer Models
These models are used to transfer energy, or heat, from one stream to another. This may involve mass and energy transfer, or it may only involve energy transfer.
| Name | Description | License | Solver |
|---|---|---|---|
| Barometric Condenser | Achieves vapour liquid equilibrium between an incoming liquor stream and a vapour stream at a user-defined pressure. Can be used as part of a Flash Train. | Heat Exchange | PB/Dyn |
| Boiler | This is a simple steam boiler. Boiler Feed Water is first heat to the required Drum Pressure then superheated to the required outlet pressure and temperature. The unit will produce steam and blowdown streams and predict the energy required by the boiler, based on the drum pressure and superheated steam conditions. | Power Plant | PB |
| Cooling Tower | This is a simple water evaporation model where water is evaporated to provide cooling. | Heat Exchange | PB |
| Desuperheater | This is a simple steam desuperheater model where water is added to reduce the degree of superheat in steam. Can be used in steam line in a Flash Train. | Power Plant | PB |
| Direct Contact Heater | Achieves vapour liquid equilibrium between incoming liquor and steam streams. Can be used as part of a Flash Train. | Heat Exchange | PB/Dyn |
| Falling Film Evaporator | In a falling film evaporator, weak liquor is pumped to the top of the unit and distributed to the tubes where it runs down as a film. Steam is entered on the shell side, the condensation of the steam provides energy to heat and if hot enough, evaporate water from the weak liquor, thus concentrating the liquor stream. | Heat Exchange | PB |
| Falling Film Evaporator 2 | In a falling film evaporator, weak liquor is pumped to the top of the unit and distributed to the tubes where it runs down as a film. Steam is entered on the shell side, the condensation of the steam provides energy to heat and if hot enough, evaporate water from the weak liquor, thus concentrating the liquor stream. | Heat Exchange | PB |
| Flash Tank | Achieves vapour liquid equilibrium of the feed stream at a user-defined pressure. Can be used as part of a Flash Train. | Heat Exchange | PB/Dyn |
| Flash Train | This is not an independent unit. It is made up of other SysCAD units such as Flash Tanks and Shell and Tube Heat Exchangers. The Flash Train will attempt to obtain equilibrium across all of the individual units by varying the pressures and temperatures. | Heat Exchange | PB |
| Heat Exchanger | Used to transfer heat from one stream to another, with no direct contact between streams. Generally the Shell and Tube Heat Exchanger which has more options should be used. | Heat Exchange | PB/Dyn |
| Shell and Tube Heat Exchanger | General purpose heat exchanger. Used to transfer heat from one stream to another, with no direct contact between streams. Requires the user to know the Overall Heat Transfer Coefficient and the heat exchange Area. Can be used as a boiler/evaporator. Can be used as part of a Flash Train. | Heat Exchange | PB/Dyn |
| Shell and Tube Heat Exchanger 2 | Used to transfer heat from one stream to another, with no direct contact between streams. Requires the user to know the Overall Heat Transfer Coefficient and the heat exchange Area. Allows user defined reactions in the tube side. Can be used as part of a Flash Train. | Heat Exchange | PB/Dyn |
| Simple Heater | This is a simplified model of the heat exchanger where only one side is simulated; the other side is reported as duty. | Heat Exchange | PB/Dyn |
| Steam Turbine | The steam turbine converts steam energy into shaft work, which can then be converted to electrical work through the generator. | Power Plant | PB/Dyn |
Mass Separation Models
These models are used to separate one or more feed streams into two or more discharge products. Some of these models are designed to handle incoming streams containing liquid and solids only, any vapour present will be lost. This will typically be reported in the unit as a vent.
| Name | Description | License | Solver |
|---|---|---|---|
| Belt Filter | Simulates a belt filter with any number of counter current wash stages. The user MUST enter data on the simple filtration wash losses. | Standard | PB/Dyn |
| Centrifugal Filter | This is a batch centrifuge. The user defines the amount of moisture remaining in the centrifuge cake and the amount of solids in the filtrate. | Standard | PB/Dyn |
| Classifier | The classifier mixes perfectly all the incoming feed streams and then, based on the user configuration, calculates the amount, temperature and composition of material reporting to the underflow and overflow. | Standard | PB/Dyn |
| Counter Current Decantation (CCD) | Used to quickly determine the concentration in the final over and under flow streams from a series of thickeners. The model is designed to be used as a quick means of determining the effect of differing numbers of stages or wash water ratio in a CCD circuit. | Standard | PB/Dyn |
| Counter Current Washer | Acts as a thickener with imperfect mixing. The user must supply the Scandrett wash efficiency, which is used to calculate the user-defined species concentrations in the under and over flows. | Standard | PB/Dyn |
| Disk Centrifuge | The user defines the amount of moisture remaining in the centrifuge cake and the amount of solids in the filtrate. | Standard | PB/Dyn |
| Drum Filter | Simulates a drum filter with wash water. The user defines the amount of liquid in the filter cake, as well as the fraction of wash water that bypasses through the cake. | Standard | PB/Dyn |
| Electrowinning Cell | The user defines the reaction by which the material is deposited onto the cathodes and the cell efficiency. The model calculates the energy requirements of the cell and the amount of heating, based on the enthalpy of reaction and the efficiency. | Standard | PB/Dyn |
| Evaporative Dryer | The Evaporative Dryer is used to remove the water from the solids in the feed stream. The model will use the user-defined moisture remaining in the cake to calculate the amount of water to be evaporated off. Any liquid impurities will remain in the cake moisture. The unit also allows for some solids loss with the evaporated moisture. | Standard | PB/Dyn |
| Filter Press | Used to separate solids and liquids. The user may add a wash water stream. The user defines the amount of moisture in the filter cake, as well as the wash efficiency. | Standard | PB/Dyn |
| Flotation Cell | A simple model of a Flotation Cell that requires the user to define the primary specie or element that is recovered to the concentrate. The user may then specify the recovery and grade of the primary specie. The recoveries of secondary species may also be defined by the user. The user may add an air stream. | Standard | PB/Dyn |
| Solvent Extraction Unit (Mixer Settler) | The Solvent Extraction may use McCabe-Thiele equilibrium diagrams to determine the extent of transfer between phases, or the user may specify the extent of reaction. The model ensures that mainly aqueous phases leave via the aqueous stream and organic phases leave through the organic stream. | Standard | PB/Dyn |
| Splitter | Used to split the feed stream(s) into two user-defined streams. The split is either based on a solid / liquid split or on an individual species split. The Tie or other separation models are usually used. | Standard | PB/Dyn |
| Thickener | The thickener model requires the user to define the solid split to the under and over flow in ProBal mode. In dynamic mode, the model will determine the solids bed height in the unit and calculate the underflow density. | Standard | PB/Dyn |
| Washer | This is the same as the thickener model, except that it also allows the user to set the mixing efficiency between the washer feed and side streams. | Standard | PB/Dyn |
Other General Models
There are a number of other general models that may be used in a project.
| Name | Description | License | Solver |
|---|---|---|---|
| Makeup Source | A source of material, used together with a Makeup Block (MU) to add material directly to a unit. | Standard | PB/Dyn |
| Bleed Sink | A destination of material, used together with a Bleed Block (BL) to remove material directly from a unit. | Standard | PB/Dyn |
| DirectLink | The DirectLink is similar to a pipe and is used to transfer material between special types of units. | Standard | PB/Dyn |
| Area Model | Used in dynamic to represent an area. Material may flow to an area. Unit models will belong to an area model. | Standard | PB/Dyn |
Process Control Models
There are a number of models in SysCAD that are used for process control purposes. Although most of these models are used mainly in dynamic simulation, some of them can be used in ProBal as well. The PID, Transmitter, Actuator and Control Link are used together as described in 'Using PID, Actuator and Transmitter'.
| Name | Description | License | Solver |
|---|---|---|---|
| General Controller (PGM) | Used to simulate plant control functions and to perform user-defined calculations. This model uses a defined programming convention and allows the users to implement loops, comparison operations, counters, etc. | Standard | PB/Dyn |
| PID Controller | Used to simulate PID controls in the model. This may be used in both dynamic and steady state models. | Standard | PB/Dyn |
| Transmitter | Mainly used to add visibility to control loops | Standard | Dyn |
| Actuator | Mainly used to add visibility to control loops | Standard | Dyn |
| Control Link | Mainly used to add visibility to control loops | Standard | Dyn |
| Set Tag List Model | Used to set predefined values from external sources into SysCAD. | Standard | PB/Dyn |
| Get Tag List Model | Used to generate a list of values from SysCAD in an external file. | Standard | PB/Dyn |
| Controller -- Events | Used to read in timed process variable changes. Data is presented in a table with single variable change against a single time column. Events do not need to be sorted by time. | Standard | Dyn |
| Controller -- Profile | The profile model reads a data file of numbers for increasing times into the model. This is used in dynamic models to adjust variables with time, such as reliability data for equipment, rainfall figures for a year, etc. | Standard | Dyn |
| Controller -- Queue | Used to read in process variable changes based on a trigger command. | Standard | Dyn |
| Controller -- Noise | Allows the user to add disturbance to a dynamic model. | Standard | Dyn |
| Controller -- Task | Used to execute commands / tasks at scheduled times. | Standard | PB/Dyn |
| General Statistics | Allows the user to collect statistical information for selected variables for a dynamic simulation, e.g tank levels, flows through pipes, etc. | Standard | Dyn |
| Flow Statistics | Generates statistics for flow variables. Eg, production rate | Standard | Dyn |
| Scheduled Events | Used to simulate downtime of a piece of equipment due to a scheduled event such as maintenance. | Standard | Dyn |
| Downtime | Used to simulate downtime of a piece of equipment due to a regular event (such as maintenance) and/or failure or other causes. | Standard | Dyn |
| Single Variable Histogram | Calculates and displays statistics for a single variable. | Standard | Dyn |
| Bivariate Statistics | Calculates and displays statistics for two variables and their correlation. | Standard | Dyn |
Size Distribution Models
These models are used in projects that contain and require the tracking and manipulation of particle size data (PSD). The models manipulate the material based on the size distribution information.
| Name | Description | License | Solver |
|---|---|---|---|
| Crusher | The crusher model can operate in three ways: a) the user defines the discharge partition curve of the product, b) the user defines the selection / breakage function for the unit or c) the user defines a feed and product size distribution based on testwork. The model uses these size distributions to calculate the extents of breakage. The unit will calculate the power required based on the product size and the bond work index of the material. | Size Distribution | PB/Dyn |
| Cyclone | The cyclone has three methods of determining the product distribution: a) The user defines the cut point and the solids fraction in the underflow, b) The Krebbs cyclone model is used, or c) The Plitt cyclone model is selected. | Size Distribution | PB/Dyn |
| Mill | The Mill may be based upon a user defined product discharge partition curve, a user defined selection / breakage function or a user defined feed and product size distribution based on testwork. The model uses these size distributions to calculate the extents of breakage. The unit will calculate the power required based on the product size and the bond work index of the material. | Size Distribution | PB/Dyn |
| Screen | The user may select one of the following screening methods:
• the Karra method, • a partition curve to define the screen products, • Whiten method, or • Whiten Beta method. | Size Distribution | PB/Dyn |
| Sieve Changing module | This module is used to change from one sieve size to another. | Size Distribution | PB/Dyn |
Pressure Changing Models
In SysCAD ProBal the stream pressure are usualy managed by setting the operating pressures in some of the unit models. However the valve and pump models are also used for setting pressure drops and boosts, especialy in vapour lines. The valve, non-return valve and reducer are identical models, therefore only the ProBal valve model is listed here.
Note: For Dynamic projects, these are documented elsewhere.
| Name | Description | License | Solver |
| Pump (ProBal) | Emulates a number of different pump types, including centrifugal, positive displacement or fixed boost. The user may define the pump manually, or choose pump curves from a pump database. NOTE: In ProBal mode, it serves as a simple pressure boost model. | Standard | PB/Dyn |
| Valve (ProBal) | Emulate a number of different valve types. The user may choose options such as a simple linear pressure drop function, or use the actual valve parameters. NOTE: In ProBal mode, it serves as a simple pressure drop model. | Standard | PB/Dyn |
Other
| Name | Description | License | Solver |
|---|---|---|---|
| Gas Pump | Designed specifically for pumping gases, it emulates a number of different gas pumps or gas fans. | ||
| Non return valve | Emulates a number of different one directional flow valve types. The user may choose options such as a simple linear pressure drop function, or use the actual valve parameters. NOTE: In ProBal mode, it serves as a simple pressure drop model. | Standard | PB/Dyn |
| Pump (ProBal) | Emulates a number of different pump types, including centrifugal, positive displacement or fixed boost. The user may define the pump manually, or choose pump curves from a pump database. NOTE: In ProBal mode, it serves as a simple pressure boost model. | Standard | PB/Dyn |
| Reducer | Used to change to a smaller pipe size. NOTE: In ProBal mode, it serves as a pressure-changing model. | Standard | PB/Dyn |
| Valve (ProBal) | Emulate a number of different valve types. The user may choose options such as a simple linear pressure drop function, or use the actual valve parameters. NOTE: In ProBal mode, it serves as a simple pressure drop model. | Standard | PB/Dyn |
| Compressor | Gas compressor used to increase the pressure of gas streams. | Standard | PB/Dyn |
Material Handling Models
These are dynamic only models used for material handling. When these models are in use, the pipes connected to the unit operation will operate in transfer mode.
| Name | Description | License | Solver |
| Belt Conveyor I (old) | A model with surge capacity, speed and a number of take-off and feed points. The material on this unit moves along the belt in discrete packages, to emulate a true belt conveyor. | Standard | Dyn |
| Belt Conveyor II | A model with surge capacity, speed and a number of take-off and feed points as well as drives with moving positions. The material on this unit moves along the belt in discrete packages, to emulate a true belt conveyor. | Standard | Dyn |
| Multi-Storage | A model for multiple parallale bins or stockpiles. | Standard | Dyn |
Sub-Models
Sub-models are contained within many different models. The user may enable these sub-models, or in some cases they are included automatically. Once the sub-model has been enabled, the access window for that sub-model becomes visible as a part of the main unit's access window. The sub-model then needs to be configured to operate correctly.
| Name | Description | License | Solver |
|---|---|---|---|
| Bleed Block (BL) | Not implemented yet. Similar to makeup block. | ||
| Environmental Heat Exchanger (EHX) | This allows the user to enable heat transfer between the environment and the unit. The user specifies the heat loss as a function of the flow through the unit. | ||
| Evaporation Block (Evap) | |||
| General Model (GM) | This gives the user a large amount of flexibility in determining the flow of material from the unit. The user may split the flow between two or more exiting streams based on percentage of total flow, phase, species, or any combination. | ||
| General Model Thermal (GMT) | This gives the user the flexibility to specify outlet stream temperatures, if they need to be different. The overall heat is conserved. | ||
| Makeup Block (MU) | This gives the user a number of flexible controlled methods to add material to the model from a Makeup Source without connecting and configuring a normal stream. | ||
| Reaction Block (RB) | The reaction block allows the user to add reactions to most of the main models. The user creates a text file containing the reactions using the designated reaction editor. The reactions are then read into the model. | ||
| Vapour Liquid Equilibrium (VLE) | This allows the user to select the vapour: liquid equilibrium behaviour of the material in the unit. | ||
| Heat Exchanger (HX) | This allows a heat exchange between a stream and the contents of a tank. |
Common Sections
There are many tab pages or groups of tags that are common to all or many models.
| Name | Description |
|---|---|
| Common Data Sections | General section on first tab page for all models. |
| Common Content Section | Component make-up material amount (eg mass) usually for surge |
| Material Flow Section | Component make-up of material flow (eq massflow) usually for pipes, flow in or out of model, etc |
| Audit | Summary of mass and energy balance (inputs/outputs) of a model |
System Models
There are a number of system "models" that are used in a project.
Species Models
The species model selected by the user determines all properties of the streams or unit contents within a flowsheet. Examples of properties are Density, Specific Heat, etc.
The default species model to be used is defined in the project configuration file. Normaly this is the Standard Species Model whose properties or generally based on the Mass Weighted Mean of the components. The properties of the individual species are taken from the species database (SysCAD.mdb). This database is compiled by the user and must be checked to ensure data used are correct. For help on the entering and modifying data in the SysCAD.mdb file, please see Species Table.
In addition to the Standard species model, which is available to all SysCAD users, other client specific species models may be developed for a specific project or client. For example, in the Aluminium industry, the generic Bayer properties model is adapted for specific refineries.
Changing Species Models describes how a specie model is selected.
| Name | Description | License | Solver |
|---|---|---|---|
| Standard Species Model | This is the default species model used by SysCAD. All physical and thermodynamic properties are calculated on a simple mass weighted mean basis. | Standard | PB/Dyn |
| Generic Bayer Species Model | Calculates the properties of the streams based on Bayer liquor properties. | Alumina | PB/Dyn |
Qualities Models
Quality models are used to further define a specie model for use in stream or unit operations. These are usually optionally created for different sections of the flowsheet.
| Name | Description | License | Solver |
|---|---|---|---|
| LockUp | The user may hide a percentage of one or more species from any reactions in the flowsheet. For example, in a gold plant, there may be 10% of the gold that cannot be recovered. This could be Locked up by the user and will never be recovered in the model. | Standard | PB/Dyn |
| Size Distribution (PSD) | The user selects the size intervals of interest and defines which species do have size characteristics. | Size Distribution | PB/Dyn |
| Solubility model | The user defines which species have solubility properties in the flowsheet. The user must then have solubility vs. temperature data for these species. | Standard | PB/Dyn |
| Specific Surface Area (SSA) | Single value representation of size distribution. Commonly used in precipitation in Alumina models. | Standard | PB/Dyn |
Alumina Models
These models are only available to users with the Alumina add-on. These models are developed especially for the use in the Alumina industry and must be used with a Bayer Stream Properties model.
| Name | Description | License | Solver |
|---|---|---|---|
| General Bayer Data | General information about the alumina Bayer properties models. Used in the alumina industry only. | Alumina | PB/Dyn |
| Generic Bayer Species Model | Calculates the properties of the streams based on Bayer liquor properties. Uses Al2O3(aq) as Alumina and Al2O3.3H2O(s) as Gibbsite. | Alumina | PB/Dyn |
| Precipitation Model | The model is for use in the alumina industry only. NOTE that this model requires Al2O3(aq) as Alumina and Al2O3.3H2O(s) as Gibbsite, therefore requires Bayer Species Model. NOTE this model is NOT compatible with Bayer3 species model. | Alumina | PB/Dyn |
| Alumina 3 Bayer Species Model | Calculates the properties of the streams based on Bayer3 liquor properties. Uses NaAl[OH]4(aq) as Alumina and Al[OH]3(s) as Gibbsite | Alumina | PB/Dyn |
| Precipitation 3 Model | The model is for use in the alumina industry only. NOTE that this model requires NaAl[OH]4(aq) as Alumina and Al[OH]3(s) as Gibbsite, therefore requires Bayer3 Species Model. NOTE this model is NOT compatible with Bayer species model. | Alumina | PB/Dyn |
Examples
General Description
Each model (unit or link), has a properties or access window, which the user can view by right clicking on the unit. The access window differs for each model. However, they all show the variables associated with that particular model. These variables fall into two main categories:
- Variables those are required to define the model.
These variables are inputs to the model and are displayed on a white background. For example in the access window below, user is required to define the variables RqdFiltSolids, RqdCakeMoist and WashBypass. The Drum filter model uses these settings to calculate the material split from the unit. - Variables those are calculated by the model.
These variables are displayed on a grey background and cannot be changed by the user. In the access window below, the model calculates CakeSolids and FiltSolids and so on.
The access window may consist of more than one section. For example, the Drum Filter shown above consists of two sections: -DFT_1- and -Audit- (If a tab marked --- is present, it indicates that it is a continuation from the previous section.)
The user can view each of these sections by clicking on their respective tab at the top of the page. The variables for that section can then be accessed.
This document attempts to describe each model, or process unit, for the user. The documentation for each model has the following format:
- General Description
This briefly outlines the purpose of the unit and how it operates within a flowsheet. - Diagram (if applicable)
This shows the default drawing of the unit with the appropriate stream connected to the unit. - Inputs and Outputs (if applicable)
This section lists all the streams that can be connected to the unit. It also gives the essential connections, without which the unit cannot operate, and the number of streams that can be connected to each connection. - Model Theory
The method by which the unit calculates the material split. Any equations used to define the unit are given in this section. - Data Sections
This attempts to quantify the variables for each unit-s access window.
