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Aspen Reactors

Aspen Reactors. Amanda Hamilton, Jonathan Kalman, Harrison Kraus, Jenny Lam, Sophie Levy, Jacob Salem. Stoichiometry of Methane Steam Reformation. C x H y + x H 2 O + heat → x CO + ( x + y /2) H 2. Using natural gas/methane ( CH 4 ) for ease of explanation

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Aspen Reactors

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  1. Aspen Reactors Amanda Hamilton, Jonathan Kalman, Harrison Kraus, Jenny Lam,Sophie Levy, Jacob Salem

  2. Stoichiometry of Methane Steam Reformation CxHy + x H2O + heat →x CO + (x + y/2) H2 • Using natural gas/methane (CH4) for ease of explanation CH4 + H2O + heat → CO + 3 H2

  3. Adding a Reaction in Aspen

  4. Adding a Reaction in Aspen

  5. RYield • Only one input feed • Basis Yield = amount of component in the output / amount input • Ideal when lacking exact specifications about stoichiometry and kinetics • Specifications (need 2) • Need either: • Temperature / pressure • Temperature change • And one of: • Temperature • Pressure • Heat duty • Vapor fraction Source: http://www.just.edu.jo/~yahussain/files/Reactors.pdf

  6. RStoic • Uses similar streams as RYield • Ideal for known reaction stoichiometry • Kinetics may be unknown or unimportant • Specifications (need 2) • Need either: • Temperature • Pressure • And one of: • Temperature • Pressure • Duty • Vapor fraction Source: http://www.just.edu.jo/~yahussain/files/Reactors.pdf

  7. RStoic - Additional Optional Specifications Combustion Selectivity Heat of Reaction

  8. REquil • Ideal for: • Reactions with an equilibrium phase • Vapor and liquid product streams • Inputs • Material streams • Reaction • Extent of reaction (optional) • Calculates equilibrium conditions based on thermodynamic data • Outputs • Vapor AND liquid product streams • Keq Source: http://www.just.edu.jo/~yahussain/files/Reactors.pdf ** No kinetics or stoichiometry needed, but does not do a rigorous analysis

  9. RGibbs • Subset of equilibrium reactors • Ideal for: • Equilibrium systems with a solid phase • Finding phase and/or chemical equilibrium • Inputs • Material streams • Reactions (If phases are constrained) • Predicts equilibrium conditions by minimizing the Gibbs Free Energy • Outputs • Product streams Source: http://www.just.edu.jo/~yahussain/files/Reactors.pdf ** No kinetics or stoichiometry needed, but does not do a rigorous analysis

  10. Reaction Kinetics Source: https://www.sciencedirect.com/science/article/pii/S0360319916333821

  11. RBatch and RCSTR • RBatch • Used to model batch or semi-batch reactor • 1, 2 or 3 phases • Continuous vapor vent, delayed or continuous feeds (optional) • RCSTR • Used to model continuous stirred tank reactor • Contents of reactor has the same properties as the outlet stream • 1, 2 or 3 phases

  12. RBatch - Specifications • Pressure specifications • Reactor operating specificationand associated parameters • Constant temperature • Temperature profile • Constant heat duty • Heat duty profile • Constant coolant temperature • Heat transfer user subroutine • Phases present in the reactor • No solid phases

  13. RBatch - Kinetics and Stop Criteria • Reaction kinetics • Stop criteria variables • Time elapsed • Mole or mass fraction of a component • Conversion of a component • Total moles or mass of material • Total volume, temperature, pressure,or vapor fraction in the reactor • Mole or mass flow rate in vent • System property (i.e viscosity)

  14. RBatch - Operation Times & Outputs • Specify operation times • Batch cycle times • Calculation times for profile results • Some outputs • Time which stop criteria satisfied • Heat load per cycle • Min and max reactor temperatures

  15. RCSTR - Specifications • 2 design variables • Pressure • Temperature or heat duty • Valid phases • Reactor specifications (phase dependent) • Reactor volume • Residence time • Phase volume, fractions, or residence time • Reaction kinetics • Some outputs • Heat duty • Phases • Residence time

  16. RPlug • Rigorous simulation of ideal plug flow reactor • 7 types of RPlug specifications • No input required • Adiabatic • Input required • Specified temperature • Constant thermal fluid temperature • Co-current thermal fluid • Counter-current thermal fluid • Specified thermal fluid temperature profile • Specified external heat flux profile

  17. RPlug - Specifications Specified temperature • Temperature input • Location in reactor (fraction of reactor length) Specified external heat flux profile • Location in reactor (fraction of reactor length) • Heat flux at location

  18. RPlug - Specifications • Overall heat transfer coefficient • Thermal fluid temperature • Location in reactor (fraction of reactor length) • Temperature atlocation Constant thermal fluid temperature Co-current thermal fluid Counter-current thermal fluid Specified thermal fluid temperature profile

  19. RPlug - Configuration • Required • Reactor length • Reactor diameter • Optional • Number of tubes • Varying diameter

  20. RPlug - Catalyst • Must indicate catalyst present • Three specifications • Catalyst loading • Particle density • Bed voidage

  21. Pros/Cons of Kinetics-Based Reactors Pros • More accurate representation of reactions • Allows reversible reactions to be properly represented Cons • Can only be used if kinetics are known • More intense calculations can slow down simulation • RBatch and RPlug can only have one feed

  22. Conclusions • Reactor requirements differ based on their inputs • Number of Feeds • Stoichiometry • Kinetics • Various reactor and feed properties • Rigorous models stay true to real-life standards • Other models still valid for estimation • Select the appropriate reactor based on information you have • Type of reaction • Kinetics, Stoichiometry, etc.

  23. Sources Aspen Plus https://web.ist.utl.pt/ist11038/acad/Aspen/AspUserGuide10.pdf http://www.just.edu.jo/~yahussain/files/Reactors.pdf http://www.chemengr.ucsb.edu/~ceweb/courses/che184b/aspenplus/PolymersPlusUserGuideVolume2.pdf https://dechema-dfi.de/kwi_media/Downloads/tc/Vorlesungen/Erlangen/slides_4.pdf

  24. Thank you for listening! Questions?

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