7 Flashcards
(23 cards)
Can you use equilibrium reaction in a CSTR unit
No- equilibrium reactions are only for equilibrium reactors
If you only know the % conversion and the equilibrium constant for a methanol synthesis reaction , which reactor model can you use on HYSYS?
Conversion, equilibrium
Reaction conversion on Hysys equation
Co + C1T + C2T^2
At chemical equilibrium, does a reversible reaction achieve minimum conversion
False- it achieves maximum conversion
Is it true that kinetic reaction can only be used to model reversible reactions?
False , it can also model reversible reactions
Simple rate is the only for reversible reactions
Is it true that the conversion in the CSTR unit depends on the volume of the reactor?
True- it does depend on the size of the reactor
Is it true that the conversion in a packed bed reactor model with the PFR unit does not depend on the void reaction ?
False, it does depend on the void fraction as this part of the reactor does not contain the catalyst and will affect the Ergun equation and pressure drop
Examples of balance based reactor units in HYSYS
Yield shift reactor
Conversion reactor
Examples of equilibrium based reactor units in HYSYS
Gibbs reactor
Equilibrium reactor
Examples of Kinetic based reactor units in HYSYS
CSTR
PFR
How to simulate reactors on HYSYS
- Add components
- Set up reaction: add reactants, products, stoichiometry (- for reactants) , conversion , constants
Conversion reaction type
Only used for conversion reactors (not for CSTR, PFR, equilibrium reactors)
What do you need to set up conversion reaction
Conversion number (not as a multiplier - decimal, and stoichiometry
What do you need for equilibrium reaction
Keq (constant), stoichiometry
What do you need for kinetic reactions
Parameters for Arrhenius equation, stoichiometry,
Can be used to model reversible or irreversible reactions
Only for CSTR, PFR
What do you need for simple rate reaction
1.Forward reaction : Parameters from Arrhenius equation
2.Reversion reaction: parameters from ln(Keq) equation
3.stoichiometry
Only for reversible reactions
Used in CSTR, PFR
Conversion reaction run phase
Sometimes vapour phase
Unless stated set DP =0
Factors that can affect chemical equilibrium
1.Change in concentration
2. Change in pressure (or volume)
3. Change in temperature
Isothermal mode in equilibrium reactor
Add an energy stream and all inlet and outlet streams must be the same
If outlet of conversion reactor is higher than inlet what does it mean
Exothermic reaction , heat is being generated
Adiabatic operation
Negative duty
Exothermic reaction
Component splitter
To fully separate components :
Equalise all stream pressures
Calculate equal temperatures
Add component splits
To solve PFR unless stated otherwise
Add pressure drop = 0
