Columns

Shortcut Column

The Shortcut Column is used to calculate the minimum reflux in a distillation column by Fenske-Underwood-Gilliland (FUG) method.

The shortcut column model have following connection ports:
  • Three Material Streams: feed, distillate and bottoms
  • Two Energy Streams: condenser duty and reboiler duty
The results are:
  • Minumum Reflux Ratio
  • Actual Reflux Ratio
  • Total Number of Stages
  • Feed Stage
  • Condenser and Reboiler Duty
  • Liquid and Vapor flows in Rectification and Stripping section
  • Pressure and Temperature of Condenser and Reboiler

To simulate a shortcut column, following calculation parameters must be provided:

  • Condenser Type Ctype
  • Heavy Key Component HKey
  • Light Key Component LKey

Among the above variables, first one Ctype is of type parameter String. It can have either of the sting values among following:

  • Total: To indicate that the condenser is Total Condenser
  • Partial: To indicate that the condenser is Partial Condenser

The other two variables are of type parameter Integer. These are to indicate high key and low key component. They can be indicated by the corresponding indices from variable C[Nc].

During simulation, their values can specified directly under Column Specifications by double clicking on the shortcut column model instance.

Additionally, following input for following variables must be provided:

  • Reflux Ratio RR
  • Heavy Key Component Mole Fraction in Distillate x_pc[2, LKey]
  • Light Key Component Mole Fraction in Bottoms x_pc[3, HKey]
  • Condenser Pressure Pcond
  • Reboiler Pressure Preb

These variables are declared of type Real. During simulation, value of all these variables need to be defined in the equation section.

Simulating a Shortcut Column

Equimolar amount of feed consisting of benzene and toluene at 100 mol/s enters a shortcut column. The feed stream enters at 370 K and 101325 Pa.

Below listed points are the step by step explaination as to how to create and simulate this shortcut column problem.

  1. Create a package named ShortcutColumn.

  2. Create a model named MS inside ShortcutColumn. This is to extend MaterialStream model.

  3. Extend the model MaterialStream and necessary property method from ThermodynamicPackages.

    extends Simulator.Streams.MaterialStream;
extends Simulator.Files.ThermodynamicPackages.RaoultsLaw;

  4. Create another new model named Shortcut inside ShortcutColumn. This is to extend ShortcutColumn model.

  5. Extend the model ShortcutColumn from UnitOperations package and necessary property method from ThermodynamicPackages.

    extends Simulator.Streams.MaterialStream;
extends Simulator.Files.ThermodynamicPackages.RaoultsLaw;

  6. Create another new model named ShortcutSimulation inside ShortcutColumn.

  7. Similar to the MaterialStream example model, import ChemsepDatabase and create variables for the compounds which are to be used from ChemsepDatabase.

    import data = Simulator.Files.ChemsepDatabase;
parameter data.Benzene benz;
parameter data.Toluene tol;

  8. Define variables for Number of components Nc and component array C. Also assign the variables created for the compounds to the component array.

    parameter Integer Nc = 2;
parameter Simulator.Files.ChemsepDatabase.GeneralProperties C[Nc] = {benz, tol};

9. Now, create three instances of the MaterialStream model MS as we require one material stream which will go as feed and two streams that comes out as distillate and bottoms. To do this, open diagram view of ShortcutSimulation model, drag & drop MS thrice as shown in fig. Name the instances as S1, S2 and S3.

  1. Now, create two instances of EnergyStream model. For this, drag and drop the EnergyStream model twice available under Streams. Name the instance as E1 and E2.

    ../_images/sc-ms-drop.png

  2. Now, create an instance of the ShortcutColumn model Shortcut. Switch to the diagram view of ShortcutSimulation model, drag & drop Shortcut. A pop up will appear asking the name of the component. Enter the name as B1.

    ../_images/sc-drop.png

12. Now double click on S1. Component Parameters window opens. Go to Stream Specifications tab. There are two parameter Nc and C for which the values are to be entered. As the value for Nc and C are already declared earlier in step 6 while defining the variables, these variables are passed here instead of the values. Repeat this for the other two material streams.

../_images/sc-in-par.png

13. Now double click on B1. Component Parameters window opens. Go to Column Specifications tab and enter the values for parameters as mentioned below:

  • Nc and C can be entered same as material stream

  • HKey represents the Heavy Key Component. Enter the index value of heavy key component from the array C[Nc]. Toluene is the heavy key whose index value in C[Nc] is 2.

  • LKey represents the Light Key Component. Enter the index value of light key component from the array C[Nc]. Benzene is the light key whose index value in C[Nc] is 1.

  • Ctype represents the type of condenser. As per the problem statement, total condenser is used. So enter Ctype as Total.

    ../_images/sc-par.png

  1. Switch to text view. Following lines of code will be autogenrated

    Simulator.Examples.ShortcutColumn.MS S1(Nc = Nc, C = C) annotation( ...);
Simulator.Examples.ShortcutColumn.MS S3(Nc = Nc, C = C) annotation( ...);
Simulator.Examples.ShortcutColumn.MS S2(Nc = Nc, C = C) annotation( ...);
Simulator.Streams.EnergyStream E1 annotation( ...);
Simulator.Streams.EnergyStream E2 annotation( ...);
Simulator.Examples.ShortcutColumn.Shortcut B1(Nc = Nc, C = C, HKey = 2, LKey = 1) annotation( ...);

  2. Now, connect the streams with unit operations. For this, switch back to Diagram view.

    ../_images/sc-connected.png

  3. Switch to text view. Following lines of code will be autogenrated under equation section

            connect(B1.En1, E1.In) annotation( ...);
        connect(E2.Out, B1.En2) annotation( ...);
connect(B1.Out2, S3.In) annotation( ...);
connect(B1.Out1, S2.In) annotation( ...);
connect(S1.Out, B1.In) annotation( ...);

  4. Specify the pressure, temperature, component mole fractions and molar flow rate for the feed stream

    S1.P = 101325;
S1.T = 370;
S1.x_pc[1, :] = {0.5, 0.5};
S1.F_p[1] = 100;

  5. Now specify the variables for shortcut column as explained earlier. So specify reflux ratio, mole fraction of heavy key component in distillate, mole fraction of light key in bottoms, condenser pressure and reboiler pressure.

    B1.Preb = 101325; B1.Pcond = 101325; B1.x_pc[2, B1.LKey] = 0.01; B1.x_pc[3, B1.HKey] = 0.01; B1.RR = 2;

  6. This completes the ShortcutColumn package. Now click on Simulate button to simulate the ShortcutSimulation model. Switch to Plotting Perspective to view the results.

Note

You can also find this package named ShortcutSimulation in the Simulator library under Examples package.

Distillation Column

The Distillation Column is used to separate the component mixture into component parts or fraction based on difference in volatalities.

The distillation column model have following connection ports: Material Streams: any number of feed streams and two products (distillate and bottom) Two Energy Streams: condenser duty and reboiler duty

The results are:

  • Molar flow rate of Distillate and Bottoms
  • Composition of Components in Distillate and Bottoms
  • Condenser and Reboiler Duty
  • Stagewise Liquid and Vapor Flows
  • Temperature Profile

To simulate a distillation column, following calculation parameters must be provided:

  • Number of Stages Nt
  • Number of Feed Streams Ni
  • Feed Tray Location InT_s
  • Condenser Type Ctype

All the variables are of type parameter Real except the last one (Ctype) which is of type parameter String. It can have either of the sting values among following:

  • Total: To indicate that the condenser is Total Condenser
  • Partial: To indicate that the condenser is Partial Condenser

During simulation, their values can specified directly under Column Specifications by double clicking on the column instance.

Additionally, following input for following variables must be provided:

  • Condenser Pressure Pcond
  • Reboiler Pressure Preb
  • Top Specification
  • Bottom Specification

Any one of the following variables can be considered as Top Specification:

  • Reflux Ratio RR
  • Molar Flow rate F_p[1]

Any one of the following can be considered as Bottoms Specification:

  • Molar Flow rate F_p[1]
  • Mole Fraction of Component x_pc[1,:]

These variables are declared of type Real and therefore all these variables need to be declared in the equation section while simulating the model.

Simulating a Distillation Column

Below listed points are the step by step explaination as to how to create and simulate this distillation column problem.

  1. Create a package named Distillation.

  2. Create a model named MS inside Distillation. This is to extend MaterialStream model.

  3. Extend the model MaterialStream and necessary property method from ThermodynamicPackages.

    extends Simulator.Streams.MaterialStream;
extends Simulator.Files.ThermodynamicPackages.RaoultsLaw;

  4. Create another new model named Condenser inside Distillation. This is to extend Cond model from DistillationColumn package.

  5. Extend the model Cond available under DistillationColumn package from UnitOperations and necessary property method from ThermodynamicPackages.

    extends Simulator.UnitOperations.DistillationColumn.Cond;
extends Simulator.Files.ThermodynamicPackages.RaoultsLaw;

  6. Create another new model named Tray inside Distillation. This is to extend DistTray model from DistillationColumn package.

  7. Extend the model DistTray available under DistillationColumn package from UnitOperations and necessary property method from ThermodynamicPackages.

    extends Simulator.UnitOperations.DistillationColumn.DistTray;
extends Simulator.Files.ThermodynamicPackages.RaoultsLaw;

  8. Create another new model named Reboiler inside Distillation. This is to extend Reb model from DistillationColumn package.

  9. Extend the model Reb available under DistillationColumn package from UnitOperations and necessary property method from ThermodynamicPackages.

    extends Simulator.UnitOperations.DistillationColumn.Reb;
extends Simulator.Files.ThermodynamicPackages.RaoultsLaw;

  10. Create another new model named DistColumn inside Distillation. This is to extend DistCol model from DistillationColumn package.

  11. Extend the model DistCol available under DistillationColumn package from UnitOperations.

    extends Simulator.UnitOperations.DistillationColumn.DistCol;

  12. Along with this create an instance of Condenser model extended earlier in step 4 and 5. Pass the

    Condenser condenser(Nc = Nc, C = C, Ctype = Ctype, Bin = Bin_t[1]);
Reboiler reboiler(Nc = Nc, C = C, Bin = Bin_t[Nt]);
Tray tray[Nt - 2](each Nc = Nc, each C = C, Bin = Bin_t[2:Nt - 1]);

  1. Create another new model named DistillationSimulation_Ex1 inside Distillation.

  2. Similar to the MaterialStream example model, import ChemsepDatabase and create variables for the compounds which are to be used from ChemsepDatabase.

    import data = Simulator.Files.ChemsepDatabase;
parameter data.Benzene benz;
parameter data.Toluene tol;

  3. Define variables for Number of components Nc and component array C. Also assign the variables created for the compounds to the component array.

    parameter Integer Nc = 2;
parameter Simulator.Files.ChemsepDatabase.GeneralProperties C[Nc] = {benz, tol};

9. Now, create three instances of the MaterialStream model MS as we require one material stream which will go as feed and two streams that comes out as distillate and bottoms. To do this, open diagram view of ShortcutSimulation model, drag & drop MS thrice as shown in fig. Name the instances as S1, S2 and S3.

  1. Now, create two instances of EnergyStream model. For this, drag and drop the EnergyStream model twice available under Streams. Name the instance as E1 and E2.

    ../_images/sc-ms-drop.png

  2. Now, create an instance of the ShortcutColumn model Shortcut. Switch to the diagram view of ShortcutSimulation model, drag & drop Shortcut. A pop up will appear asking the name of the component. Enter the name as B1.

    ../_images/sc-drop.png

12. Now double click on S1. Component Parameters window opens. Go to Stream Specifications tab. There are two parameter Nc and C for which the values are to be entered. As the value for Nc and C are already declared earlier in step 6 while defining the variables, these variables are passed here instead of the values. Repeat this for the other two material streams.

../_images/sc-in-par.png

13. Now double click on B1. Component Parameters window opens. Go to Column Specifications tab and enter the values for parameters as mentioned below:

  • Nc and C can be entered same as material stream

  • HKey represents the Heavy Key Component. Enter the index value of heavy key component from the array C[Nc]. Toluene is the heavy key whose index value in C[Nc] is 2.

  • LKey represents the Light Key Component. Enter the index value of light key component from the array C[Nc]. Benzene is the light key whose index value in C[Nc] is 1.

  • Ctype represents the type of condenser. As per the problem statement, total condenser is used. So enter Ctype as Total.

    ../_images/sc-par.png

  1. Switch to text view. Following lines of code will be autogenrated

    Simulator.Examples.ShortcutColumn.MS S1(Nc = Nc, C = C) annotation( ...);
Simulator.Examples.ShortcutColumn.MS S3(Nc = Nc, C = C) annotation( ...);
Simulator.Examples.ShortcutColumn.MS S2(Nc = Nc, C = C) annotation( ...);
Simulator.Streams.EnergyStream E1 annotation( ...);
Simulator.Streams.EnergyStream E2 annotation( ...);
Simulator.Examples.ShortcutColumn.Shortcut B1(Nc = Nc, C = C, HKey = 2, LKey = 1) annotation( ...);

  2. Now, connect the streams with unit operations. For this, switch back to Diagram view.

    ../_images/sc-connected.png

  3. Switch to text view. Following lines of code will be autogenrated under equation section

            connect(B1.En1, E1.In) annotation( ...);
        connect(E2.Out, B1.En2) annotation( ...);
connect(B1.Out2, S3.In) annotation( ...);
connect(B1.Out1, S2.In) annotation( ...);
connect(S1.Out, B1.In) annotation( ...);

  4. Specify the pressure, temperature, component mole fractions and molar flow rate for the feed stream

    S1.P = 101325;
S1.T = 370;
S1.x_pc[1, :] = {0.5, 0.5};
S1.F_p[1] = 100;

  5. Now specify the variables for shortcut column as explained earlier. So specify reflux ratio, mole fraction of heavy key component in distillate, mole fraction of light key in bottoms, condenser pressure and reboiler pressure.

    B1.Preb = 101325; B1.Pcond = 101325; B1.x_pc[2, B1.LKey] = 0.01; B1.x_pc[3, B1.HKey] = 0.01; B1.RR = 2;

  6. This completes the ShortcutColumn package. Now click on Simulate button to simulate the ShortcutSimulation model. Switch to Plotting Perspective to view the results.

Note

You can also find this package named ShortcutSimulation in the Simulator library under Examples package.

Distillation Column

The Distillation Column is used to separate the component mixture into component parts or fraction based on difference in volatalities.

The distillation column model have following connection ports: Material Streams: any number of feed streams and two products (distillate and bottom) Two Energy Streams: condenser duty and reboiler duty

The results are:

  • Molar flow rate of Distillate and Bottoms
  • Composition of Components in Distillate and Bottoms
  • Condenser and Reboiler Duty
  • Stagewise Liquid and Vapor Flows
  • Temperature Profile

To simulate a distillation column, following calculation parameters must be provided:

  • Number of Stages Nt
  • Number of Feed Streams Ni
  • Feed Tray Location InT_s
  • Condenser Type Ctype

All the variables are of type parameter Real except the last one (Ctype) which is of type parameter String. It can have either of the sting values among following:

  • Total: To indicate that the condenser is Total Condenser
  • Partial: To indicate that the condenser is Partial Condenser

During simulation, their values can specified directly under Column Specifications by double clicking on the column instance.

Additionally, following input for following variables must be provided:

  • Condenser Pressure Pcond
  • Reboiler Pressure Preb
  • Top Specification
  • Bottom Specification

Any one of the following variables can be considered as Top Specification:

  • Reflux Ratio RR
  • Molar Flow rate F_p[1]

Any one of the following can be considered as Bottoms Specification:

  • Molar Flow rate F_p[1]
  • Mole Fraction of Component x_pc[1,:]

These variables are declared of type Real and therefore all these variables need to be declared in the equation section while simulating the model.

Absorption Column

The Absorption Column is used to separate gas mixture by scrubbing through a liquid solvent.

The absorption column model have following connection ports: Material Streams two feed streams and two products

The results are:

  • Molar flow rate of Product streams
  • Composition of Components in Product streams
  • Stagewise Liquid and Vapor Flows
  • Temperature Profile

To simulate an absorption column, the only calculation parameter which must be provided is Number of Stages Nt.

During simulation, its value can specified directly under Column Specifications by double clicking on the column instance.

Simulating an Absorption Column