Implementation of a 4 phase flash in HYSYS
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The document discusses the implementation of a 4-phase flash operation in HYSYS for detecting a third liquid phase in hydrocarbon simulations, addressing limitations of the existing flash capabilities. The proposed solution involves creating an extension to HYSYS that performs stability tests and allows for accurate phase separation detection in various industrial applications, particularly concerning mercury management. Key improvements include enhanced property modeling and solubility prediction to better simulate hydrocarbon systems with heavy fractions and immiscible components.
Implementation of a 4 phase flash in HYSYS
- 1. Implementation of a 4-phase flash for the detection of a third liquid phase in hydrocarbon process simulation using HYSYS Speaker: Howard Wilson, James Holoboff D. Embry1, H. Wilson1, J. Holoboff2 and M. Khoshkbarchi2 1ConocoPhillips Company 2Process Ecology Inc.
- 2. Outline • Background & Industry Applications • Limitations of HYSYS Flash • Proposed Solution • Stability Test Utility • 4-Phase Flash Unit Operation Extension • Impact on Simulation Results • Demonstration
- 3. Background • Liquid-liquid equilibrium is a common phenomenon in hydrocarbon processes • Possibility for liquid phases to further phase separate (i.e. – 3 liquid phases) • 3 liquid phases cannot be handled in HYSYS
- 4. Industry Applications (1) • Hydrocarbon systems with heavy fractions resulting in: heavy phase (wax / asphaltene) light hydrocarbon phase water phase • Immiscible tracer added to two-liquid phase system • Some mixtures with perfluoro compounds
- 5. Industry Applications (2) • Solvent/polymer/water mixtures • Oil and natural gas applications, where mercury-free product is required • Cryogenic applications where impurities such as mercury must be addressed
- 6. Industry Applications - Mercury (1) • Natural gas may contain low levels of mercury • In cryogenic applications (e.g. - LNG, nitrogen rejection), mercury can concentrate in cryogenic aluminum heat exchangers • Any contact of liquid mercury with aluminum can cause liquid metal embrittlement and lead to catastrophic failure
- 7. Industry Applications - Mercury (2) • For some applications, “mercury-free” gas product streams are required • Mercury may need to be removed to prevent catalyst deactivation and heat exchanger problems in downstream processing
- 8. Industry Applications – Simulation • From a simulation perspective, It would be useful to determine when / where mercury is predicted to form a separate phase • HYSYS can be used to model industry applications, but may not adequately predict properties of mercury or formation/separation of mercury phase
- 9. Improvements to HYSYS 1. Improve pure component property model (vapor pressure) 2. Improve predicted solubility of key components in hydrocarbons and water (modify interaction parameters) 3. Detect presence of key components as a separate phase • This presentation focuses on #3
- 10. Limitations of HYSYS Flash • If there are in reality three liquid phases HYSYS incorrectly distributes components resulting in creation of unstable phases • Standard HYSYS flash can check for two liquid phases and a vapor phase Maximum Phases in HYSYS – 3 (VLL)
- 11. Proposed Solution • Perform stability calculation on stream: • Select “test” component • Calculate Gibbs energy of pure component (Gibbs1) • Calculate Gibbs energy of specified component in stream (Gibbs2) • If Gibbs1 < Gibbs2 then new phase with pure component is stable
- 12. Proposed Solution • Create additional functionality in HYSYS to check for additional phases: • Develop HYSYS unit operation extension, which includes: • Compiled code (DLL) • View file (EDF) • Report file (RDF)
- 13. Required skills • Programming (e.g. Visual Basic, C++) • Familiarity with HYSYS automation interfaces • Knowledge of user interfaces and formats (EDF, RDF) • Understanding of interaction between unit operation and flowsheet • General and HYSYS-specific thermodynamics knowledge (e.g., understanding of HYSYS reference state) • Extensions required about 7 weeks development time
- 14. Adding Unit Operation Extension in HYSYS • Register the HYSYS extension • Operation filtered as “Extension” type
- 15. Stability Test Utility • Multiple streams can be selected • Display status & departure: Unstable – test component could form a pure phase Stable – test component will not form a pure phase Incipient – test results inconclusive based on tolerance value
- 16. Stability Test Utility • Any available component can be selected as the “test component” • A tolerance is selected
- 17. Four-Phase Separator • Connections set up much like conventional 3-phase separator in HYSYS
- 18. Four-Phase Separator • Select test component • Phase Order – density vs. component • Settings – stability tolerance, objective function
- 19. Sample Gas Plant Simulation
- 20. Effect of changes on estimated Dehy Inlet Hg concentration 64776252.068245 6477630.21824 76760.0282 Updated with 4-phase Flash (ppb Hg) Updated properties & BIPs (ppb Hg) Standard HYSYS thermo (ppb Hg) Feed (ppb Hg)
- 21. Demonstration
- 22. Thank-you! • Thanks to ConocoPhillips and Process Ecology management for permitting discussion of this material