Chapter 5 - Ideal Reactors for Single Reaction Flashcards
in this reactor, the reactants are initially charged into
a container, are well mixed, and are left to react for a certain period
batch reactor
this reactor has an unsteady-state operation where composition
changes with time; however, at any instant the composition throughout the
reactor is uniform.
batch reactor
in this reactor, characterized by the fact that the flow of fluid
through the reactor is orderly with no element of fluid overtaking or mixing with
any other element ahead or behind
plug flow reactor
in this reactor, there may be lateral mixing of
fluid but there must be no mixing or diffusion along the flow path
plug flow reactor
necessary and sufficient condition for ______ reactor is for the
residence time in the reactor to be the same for all elements of fluid
plug flow
a reactor in which the contents are well stirred and uniform throughout
mixed flow reactor
in this reactor, the exit stream from this reactor has the same composition as the fluid within
the reactor
mixed flow reactor
refers to the volume of fluid in the reactor
V, reactor volume
in this reactor, there is no fluid enters or leaves the reaction mixture
during reaction
batch reactor
the natural performance measure for a batch reactor
reaction time, t
time required to process one
reactor volume of feed measured
at specified conditions
space time
number of reactor volumes of
feed at specified conditions which
can be treated in unit time
space velocity
in this reactor, the composition of the fluid varies from point to point
along a flow path
plug flow reactor
in PFR, _____ is constant but _____ is certainly dependent on the concentration or convesion of materials
Fao, rA
in ___ rA varies while in ___ rA is constant
PFR, MFR
for systems of changing density, it is more convenient to use ___________
conversions
when the density is constant, Ea = ?
0
for systems of constant density (constant-volume batch and constant density plug flow), the performance equation are ______ and equations can be used interchangeably.
identical
for systems of changing density, there is (direct, no direct) correspondence between the batch and plug flow ewuations
no direct
it is applicable to an even number of uniformly spaced intervals on the Xa axis
simpson’s rule
in PFR, as space time increases, concentration of reactant ______
decreases
in batch reactor, as reaction time increases, concentration of reactant __________
decreases
reactors whose properties of the system do not change with time
steady state reactor
reactors whose properties of the system changes with time and rate of reaction decreases with time
unsteady state reactor
partially batch and partially continuous; offers good control of reaction speed because the reaction proceeds as reactants are added.
semi batch reactors
which achieves higher conversion among the flow reactors for identical conditions?
for identical conditions, i.e for some reactor volume conversion achieved in PFR is higher than in MFR
in this reactor, rate of reaction is independent of time and dependent on position or distance
PFR
in this reactor, rate of reaction is independent of position and dependent on concentration of reactants
MFR
reactor that is most suitable for very high pressure gas phase reaction
tubular flow reactor
reactor that is most suitable for isothermal operation
back-mix reactor
reactor for reactions where the reaction rate is fairly to extremely high, for large scale production and for good quality control
PFR
a large CSTR, small CSTR and PFR of fixed volume are available. In general, how would
you arrange them for getting maximum conversion for reactions of order >1 and <1. Why
For n>1 arrangement is PFR followed by small CSTR followed by large CSTR to
maintain the reactant concentration as high as possible.
For n<1 arrangement is large CSTR followed by small CSTR followed by PFR.
For n=1 arrangement for first order reaction sequencing does not affect conversion. It
can be either PFR followed by MFR or MFR followed by PFR.
reactor used to increase conversion rate by dividing the product stream and a part returned to the reactor as recycle
recycle reactor
provides means for obtaining various degree of back mixing
recycling
ratio of the volume fluid returned to the
reactor entrance to the volume of fluid leaving the system or reactor
recycle ratio
recycle ratio can be made to vary from _____ to infinity
zero
as the recycle ratio is raised, the behavior shifts from ___ (R = 0) to
______ (R = infinity)
PFR, MFR
when will the recycle reactor behave like a CSTR?
when the recycle ratio ‘R’ becomes or tends to infinity (R=infinity), the recycle reactor
behaves like a CSTR
what do you mean by optimum recycle operation?
when material is to be processed to some fixed final conversion in a recycle reactor,
there must be a particular recycle ratio ‘R’ that minimizes the reactor volume or space time.
ratio of moles of desired product formed at
any instant to moles of reactant (A) reacted at any instant; it is a function of Ca
instantaneous fractional yield
is the mean of the instantaneous fractional yields at all points within the reactor
overall fractional yield
both instantaneous and overall fractional yield depend on the ______ within the reactor
type of flow
is the ratio of moles of desired product to moles of undesired product
selectivity
ratio of moles of product formed to moles of reactant either fed or consumed
yield
how does the concentration level of reactants affect the product distribution in parallel reactions?
High reactant concentration favors the reaction of higher order.
Low reactant concentration favors the reaction of lower order.
The concentration level has no effect on the product distribution for reactions of the
same order
