Page 223 - Elements of Chemical Reaction Engineering 3rd Edition

Sec. 4.7 Unsteady-State Operation of Reactors 195
One now has only to specify the parameter values (k, V,, u,,F,,) and the initial
conditions to sdlve these equations for NA and NB .

Writing the Semibatch Reactor Equations in Terms of Conversion. Con-
sider the reaction
A+B C+D

in which B is fed to a vat contaihing only A initially. The reaction is first-order
in A and first-order in B. The number of moles of A remaining at m.y time, t,
can be found from the balance,

The limiting
reactant is the
one in the vat
- - -
N A NAO NAOx
where X is the moles of A reacted per mole of A initially in the vat. Similarly,
for species B.
[ attimet 1 number of mole] + of B added to of B reacted up
of mole]
number of moles
of mole] -
=
of B in the vat
of B in the vat
the vat
initially
to time 1'
NBi + dt A NAOx
(41-62)
For a constht molar feed rate

NB = N,, + FBot- NAOX (4-63)
A mole balance on species A gives

The number of moles of C and D can be taken directly from the stoichiometric
table; for example,
N, = N,, + N,,X

For a reversible second-order reaction A+B a CSD for which the
rate law is /

(4-65)