and the volumetric flow rate is
For this process, determine the molar flow rate of species A in terms o c , , and
v . When 0 5
. , determine the bulk concentration,
cA b ,and the area‐
averaged concentration, c
A . Use these results to determine the difference between
A Q .
4‐13. A flash unit is used to separate vapor and liquid streams from a liquid stream by lowering its pressure before it enters the flash unit. The feed stream is pure liquid water and its mass flow rate is 1000 kg/h. Twenty percent (by mass) of the feed stream leaves the flash unit with a density 3
10 kg / m . The
remainder of the feed stream leaves the flash unit as liquid water with a density 3
1000 kg / m . Determine the following:
1. The mass flow rates of the exit streams in kg/s.
2. volumetric flow rates of exit streams in m3/s.
4‐14. Show that Eq. 4‐79 results from Eq. 4‐78 when either
or x is constant
over the area of the exit.
4‐15. Use Eq. 4‐79 to prove Eq. 4‐80.
4‐16. Derive Eq. 4‐82 given that either v n or A is constant over the area of the exit.
4‐17. Prove Eq. 4‐86.
and the unknown mole fractions for the distillation process
described in Sec. 4.7 subject to the following conditions:
M 1 = 1200 mol/h
M 2 = 250 mol/h
M 3 = ?
x A = 0.3
x A = 0.8
x A = ?
x B = 0.2
x B = ?
x B = 0.25
x C = ?
x C = ?
x C = ?
4‐19. A continuous filter is used to separate a clear filtrate from alumina particles in a slurry. The slurry is 30% by weight of alumina that has a specific gravity of 4.5. The cake retains 5% by weight of water. For a feed stream of 1000 kg/h, determine the following:
1. The mass flow rate of particles and water in the input stream 2. The volumetric flow rate of the inlet stream in m3/s.
3. The mass flow rate of filtrate and cake in kg/s.
4‐20. A BTX unit, shown in Figure 4.20, is associated with a refinery that produces benzene, toluene, and xylenes. Stream #1 leaving the reactor‐reforming Figure 4.20. Reactor and distillation unit
unit has a volumetric flow rate of 10 m3/h and is a mixture of benzene ( A), toluene ( B), and xylenes ( C) with the following composition: 3
c 6,000 mol/m ,
c 2 , 000 mol/m ,
c 2 , 000 mol/m3