1. Terry A. Ring Chemical Engineering University of Utah
AIChE Project Week 4
Terry A. Ring
Chemical Engineering
University of Utah

2. Questions for the Week How is Heat Integration done in Aspen?
After determining which HXs can be linked using pinch analysis.
Add in cross HX for each two linked HXs
Set desired inlet/outlet temps

3. Questions How To Deal With Impurities
1) How much impurity will Reactor Generate
Reactors
RGibbs to see if a Species will be formed under reaction Conditions
2) How will impurity affect Separation
Separation Train
Add a small amount of impurity
Determine where the impurity ends up in the separation train

4. Does impurity force a different separation sequence?
Non Condensable
Purge it out
Flash it out before the Separation Train
“Light Flash”
Flash To Remove Just the Impurity
Can you sell the Secondary Product in an impure state?
Impurity
Condensable
See How Separation Train Handles the Condensable Impurity
Contamination of Desired Product?
Improve Separation
Higher Reflux Ratio
More Trays
Add Addition Separation Units To Specifically Remove Impurity
Contamination of Recycle?
Recycle it and let the back reaction return this impurity to feed for subsequent reaction to products
Separate it out before recycle
Contamination of Waste of Water?
Alternative waste treatment plan
Contamination of Secondary Product?
Separate out Impurity before sale
Can you sell the impurity on its own?

5. Questions on Cost Analysis
How do you cost the reactor?
Use Shell and Tube HX – Catalyst in the Tubes
Sizing Factor is the HX Area
Tube length max = 20 ft
How do you cost the distillation column?
Pressure Vessel
Platforms (stairs)
Trays, Plates, Packing (and distributors)
Pumps
Electric Motors
For This Problem Ignore Spares
Reminders
Add in the costs for
Electricity Hub
Natural Gas Hub
Cooling water Plant
Refrigeration Plant
Steam Plant – this needs boiler feed water
Add waste water treatment

6. Questions on Consequences Analysis
How do I set up this analysis?
Locations
Major sources of Fuel – Feed Storage Tank and Product Storage Tank
Vessels where Temperature is High
Vessels where Pressure is High
Looking for (big costs to others/Law Suits)
Consequences large enough to affect businesses near plant
Consequences large enough to affect housing near plant.
What is the volume of vapor in a Tank of liquid?
Use the volume of the elliptical head as a minimum.

7. Team Rating Form Required of Each Individual on a Team Rate yourself
Rate other team members
3 Ratings for each form

8. Other Questions?

9. Other Slides

10. Questions How do we enter the rate data? Go to Aspen Help!
Type Kinetics
LHHW Kinetics
Kinetic Factor is forward Rate Constant
Backward Rate constant is
Kinetic Factor*K2
K2 is the Reaction Equilibrium Constant

11. Concentration Various Options Equilibrium Constants
Keq=Aeq exp(ΔGeq/RT)
To convert
Ln(Keq) = ln(Aeq) + ΔGeq/RT
In general
ΔGeq= ΔH – TΔS
ΔH = ΔHo + Δ𝐶𝑝 𝑑𝑇
ΔCp=Rg*(Δa+ ΔbT+ ΔcT2+ Δd/T2)

12. Questions How To Deal With Impurities
1) How much impurity will Reactor Generate
Reactors
RGibbs to see if a Species will be formed under reaction Conditions
2) How will impurity affect Separation
Separation Train
Add a small amount of impurity
Determine where the impurity ends up in the separation train

13. Various Reactors, Various Reactions

14. Optimum Inlet Temperature Exothermic Rxn
CSTR
PFR