Developing a Dynamic Simulation in Aspen HYSYS

1. Create a New Aspen HYSYS Simulation:

Open Aspen HYSYS and create a new case.

2. Select the Fluid Package:

Go to the Fluid Package section.

Select a thermodynamic model (e.g., Peng-Robinson) suitable for hydrocarbon systems.

3. Add Components:

In the Components section, add the components of natural gas:

Methane (C1)

Ethane (C2)

Propane (C3)

Butane (C4)

Pentane (C5)

Carbon Dioxide (CO₂)

Hydrogen Sulfide (H₂S)

Water (H2O)

4. Build the Process Flow Diagram (PFD):

In the Flowsheet section, add a Three-Phase Separator.

Connect the streams:

Feed Stream: Set typical natural gas conditions (e.g., pressure: 50 bar, temperature: 30°C, molar flow rate: 1000 kmol/hr).

Connect the Feed Stream to the Three-Phase Separator.

5. Set Up the Separator:

Double-click on the Three-Phase Separator to configure its parameters.

Set the operational conditions, such as:

Pressure: 50 bar

Temperature: 30°C

Define the product streams:

Gas Outlet

Liquid Hydrocarbon Outlet

Water Outlet

6. Switch to Dynamic Mode:

After configuring the static setup, switch to Dynamic Mode:

Go to the Simulation menu and enable Dynamic calculations.

7. Dynamic Equipment Setup:

Replace static equipment models with dynamic ones:

For the Three-Phase Separator, ensure it has a volume defined to account for holdup capacity.

8. Add Controllers:

In the Control section, add the following controllers:

Pressure Controller (PC): To maintain the separator’s pressure.

Level Controller (LC): To control liquid levels in the separator.

Temperature Controller (TC): To adjust heating/cooling for temperature control.

Connect these controllers to the respective process equipment and streams.

9. Define Initial Conditions:

Set initial conditions for the system, including:

Initial pressures for each stream.

Initial liquid levels in the separator.

Flow rates for each outlet stream.

10. Introduce Disturbances:

Simulate disturbances to observe dynamic responses:

For example, introduce a sudden increase in methane content in the feed or a step change in feed flow rate.

11. Run the Simulation:

Start the simulation and monitor the system's response using trend plots for:

Pressure

Flow rate

Liquid levels

Controller responses

12. Analyze Results:

Evaluate how the system stabilizes after disturbances:

Analyze startup times, controller performance, and overall system response.

13.Visualization and Analysis

You can visualize the results using Aspen HYSYS’s built-in plotting tools:

Trend Plots: Monitor key variables over time to see how the system responds to changes.

Control Performance Analysis: Assess how effectively the controllers maintain stability.

Conclusion

By following these steps, you can create a dynamic simulation of a natural gas separation process in Aspen HYSYS. This setup will help you analyze how the system reacts to various operational changes and improve your understanding of dynamic behavior in oil and gas processes.