Page 174 - Modelling in Transport Phenomena A Conceptual Approach
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154 CHAPTER 6. STEADY-STATE MACROSCOPIC BALANCES
Determine the concentration of species d in each reactor if the feed to the first
reactor contains 1.5mol/L of d and the volumetric flow rates of the streams are
given as follows:
Stream Volumetric Flow Rate
No (L/ h)
1 500
7 200
9 50
11 100
Solution
Assumptions
1. Steady-state conditions prevail.
2. Concentrations of species within the reactor are uniform as a result of perfect
mixing.
3. Liquid density remains constant.
Analysis
Conservation of total mass, Eq. (6.2-l), reduces to
mi, = mat (1)
Since the liquid density is constant, Eq. (1) simplifies to
&in = Qout (2)
Only four out of eleven streams are given in the problem statement. Therefore, it
is necessary to write the following mass balances to calculate the remaining seven
streams:
= Q6 = 500
500 + 100 = Q2
Q2 + e10 = Q3
Q3+50= e4
Ql3 = Q5
Q~ = Q6 + 200
200 = 50 + &lo
Simultaneous solution of the above equations gives the volumetric flow rate of each
stream as:
