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

2. @Amanda and Jacob, I thought this photo might be useful for intro or summary
This is mine - Jacob B. Salem, 2/7/19, 3:11 pm WAY TO IGNORE THIS
This should be an intro slide we can put a nice red box around the kinetic based ones or show it every time we switch between boxes!!
Reason for RPLUG over CSTR
“The reactor was simulated using the RPLUG model with a ‘constant medium temperature’ as
the dynamic heat transfer selection. This kind of reactor is the best choice to simulate plug flow
configuration with composition changing along the reactor length (or catalyst mass), since it allows the
full definition of kinetics and, hence, the prediction of reactor output under widely different conditions.
The kinetic equation involves the integration of appropriate composition and rate terms along the reactor profile.”
Say that we’re focusing on RPlug because its what we believe will be used for the project

3. 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

4. Adding a Reaction in Aspen
Simulation -> Reactions -> hit new -> choose Powerlaw -> input components

5. Adding a Reaction in Aspen

7. Source: http://www.just.edu.jo/~yahussain/files/Reactors.pdf
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:

8. Source: http://www.just.edu.jo/~yahussain/files/Reactors.pdf
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:
Duty
Vapor fraction
Source:

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

11. Source: http://www.just.edu.jo/~yahussain/files/Reactors.pdf
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:
** No kinetics or stoichiometry needed, but does not do a rigorous analysis

12. Source: http://www.just.edu.jo/~yahussain/files/Reactors.pdf
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:
** No kinetics or stoichiometry needed, but does not do a rigorous analysis

14. Reaction Kinetics
Source:

18. RBatch and RCSTR RBatch RCSTR
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

19. RBatch - Specifications
Pressure specifications
Reactor operating specification and 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

20. 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)

21. 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

22. 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

23. 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

24. 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

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

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

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

28. Pros/Cons of Kinetics-Based Reactors
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
1st point - These models are rigorous and are thus accepted as more accurate to a real reaction. if you have kinetic information, this is additional information that gives a more realistic and accurate result. 2nd point - for a reversible reaction, fwd and backward may have different kinetics. This is not assumed in non-kinetic based reactors

29. 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.
Reactor properties - length, diameter, catalyst Feed properties - heat transfer coefficient, temperatures,
Type of reaction - batch, adiabatic, etc.

30. Sources
Aspen Plus

31. Thank you for listening!
Questions?