Semester 2 Reaction Engineering Flashcards
What are the 3 steps for a chemical reactor process
Mixing, reaction, separation
What is homogenous chemical reaction
Single phase chemical reaction
What is a heterogeneous chemical reaction
Reacting taking place with at least 2 distinct phases
What is the function of catalyst
Increase ror without getting used up
What us mass balance
Accounting materials entering, converting, accumulating and leaving within the reactor
What is energy balance
Accounting heat entering, leaving, accumulating, forming Orr disappearing from or within g the reactor
What is stoichiometry
Moles of reactant react to yield of product produced
Rate law equation
-rA=kCna
What is contacting in chemical reaction
How reactants are connected for the reaction to take place in a reaction plant
What is the performance equation
Output=f(input,kinetics,contacting)
Rate of reaction for the volume of reacting fluid
Ri= 1/v x dn/dt
Ror of mass of solid in fluid solid system
Ri’=1/w x dn/dt
Ror of the volume of solid in solid gas system
Ri’’=1/s x dv/dt
Ror of solid in gas-solid system
Ri’’’=1/v x dn/dt
Ror of volume of reaction, if different from the rate based on volume of fluid
Ri’’’’=1/vr x dn/dt
What is rA
Rate of formation
What is -rA
Rate of dissapearence
What is the stoichiometric equation of aA+bB—>rR+sS
-rA/a=-rB/b=rR/r=rS/s
Definition of reaction law rate
Algebraic equation for reaction rate as a function of properties of the reaction materials and conditions
What is elementary reaction
Reaction with no intermediate, single step
Units for 0 order
Mol L-1 s-1
Unit for 1st order
S-1
unites for 2nd order
Mol-1 L s-1
What is the rate reaction for gas phase reaction, including simplified version (show how it is derived)
Pv=nRT, C=n/v
So, p=CRT, C=p/RT
-rA=kCnA
-rA=k(pA/RT)n
Where k’=k/(RT)n
So, -rA=k’Pna
Ahrenius equation
K=k0e^-e/RT
Ahrenius equation interms of y=mx+c
LnK=lnK0-(E/R)1/T
Interms of what is the conversion of reactant used in batch process
Moles
Signs of
Fractional conversion
Initial amount of moles
Moles A present after certain time
XA
NA0
NA
2 equation of the conversion of A in time t for batch process
Xa=(NA0-NA)/NA0
Xa=1-(NA/NA0)
No of moles of A interms of NA0 and XA, equation
NA=NA0(1-XA)
Fractional conversion equation when volume is constant
XA=1-CA/CA0
Conversion rate in continuous process
XA=(FA0-FA)/FA0
What type of system batch reactor
Closed system, neither inflow nether outflow
What happens to concentration over time in batch reactor
Changes
What is batch reactor usually used for
- Same volume prediction
- Flexibility of multi product operation
- Lower capital cost
- Lab testing
What is continuous reactors used for
Long production runs and products made in large scale
What happens to conditions in continuous process over time
Doesn’t change
When is CSTR used
Large scale, liquid phase, intense agitation
condition of CSTR can work
Up to 300 degrees and 300 bar
What about the concentration in CSTR
Assume perfect mixing, C is the same everywhere in the reactor
ADV of CSTR
Cheap construction cost
Good T control
Disadvantage of CSTR
Mix might not be done properly
Reactants might bypass through outlet
