Residence Time Distribution Flashcards
What is the definiation of residence Time ditribution (RTD)
it the time spent by a fluid elemnet in the vessel
What does the RDT enables us?
it enables traceability, develop control stragtegies
what are the two types of flow patterns?
plug flow and mixed flow
Why do we like this flow patterns?
- one or the other often is optimum no matter what we are designing for
- these two patterns are simple to treat
How do we account for the real equipment which deviates from these ideals flow pattern?
by using the interrelated factots such as RTD, state of affregation and earliness and latness of mixing
What are the reason for the deviation from the two ideal flow patterns?
- Channeling of flui
- Recycling of fluid
- by creation of stagnent region sin the vessel
Definition of exit age distribution E?
it reflexs the time of the fluid passing through the vessel, since fluid could tak different routes through the reactor
what is the unit of E
1/t
How can we present E in such a way that the curve is unity? (Know how to write the equation)
By normalizing the distribution
What is the one restriction of the E curve?
that the fluid only enters and only leaves the vessel one time
what is the meaning of that restriction on the E curve
that there should be no flow or diffusion or upflow eddies at the entrance or at the vessel exit
How is the restriction condition called?
closed vesel boundary condition
what is a open vessel boundary?
where elements of fluid can cross the vessel boundary more than one time
What does the open vessel represent?
the fraction of exit stream of age between t and t+ dt
What is the formel for the fraction?
E dt [-]
what does the term “age” means?
for an element of th exit stream refers to the time spent by that elemnt in th vessel
How does the exit age distribution curve E looks like?
Do you know how to draw it?
What is the formel for the fraction younger than age t(1)
Do you know it?
What is the formel for the fraction older than age t(1)
Do you know it?
After the normalization process, what is the value of the AUC?
one
on what does the value on the x-aches depends on?
on the amount of concentration used
the tracer
what are the different ways to study the flow pattern in vessels?
pulse, step, periodic and random input
How do you fine E curve from the C(puls) curve?
by simply change the concentration scale such that the area under the curve is unity
what are the useful information obtainable from the puls trace experiment? (know how to draw the curve)
- instantaneously introduce M units of tracer into the fluid entering the vessel
Record the leaving traces
Evalute the area under the curve
Evalution the mean
