Coulson LLE Flashcards
In the extraction of acetic acid from an aqueous solution with benzene in a packed column of height
1.4 m and of cross-sectional area 0.0045 m2, the concentrations measured at the inlet and outlet of
the column are as shown in Figure 13.22.
Determine the overall transfer coefficient and the height of the transfer unit.
Acid concentration in inlet water phase, CW2 = 0.690 kmol/m3
Acid concentration in outlet water phase, CW1 = 0.685 kmol/m3
Flowrate of benzene phase = 5.7 cm3s or 1.27 × 10−3 m3/m2s
Inlet benzene phase concentration, CB1 = 0.0040 kmol/m3
Outlet benzene phase concentration, CB2 = 0.0115 kmol/m3
The equilibrium relationship for this system is:
C
∗
B
C
∗
W
= 0.0247
- 8 × 10−4 kmol/s m3(kmol/m3)
1. 63 m
In order to extract acetic acid from dilute aqueous solution with isopropyl ether, the two immiscible
phases are passed countercurrently through a packed column 3 m in length and 75 mm in diameter.
It is found that, if 0.5 kg/m2s of the pure ether is used to extract 0.25 kg/m2s of 4.0 per cent
acid by mass, then the ether phase leaves the column with a concentration of 1.0 per cent acid
by mass.
Calculate:
(a) the number of overall transfer units based on the raffinate phase, and
(b) the overall extraction coefficient based on the raffinate phase.
The equilibrium relationship is given by:
(kg acid/kg isopropyl ether) = 0.3 (kg acid/kg water).
- 461 kg/m3s(kg/kg)
5. 53
In the extraction of acetic acid from an aqueous solution with benzene a packed column of height 1.4 m and cross-sectional area 0.0045 m2, the concentrations measured at the inlet and the outlet of the column are: acid concentration in the inlet water phase, CW2 = 0.69 kmol/m3. acid concentration in the outlet water phase, CW1 = 0.684 kmol/m3. flowrate of benzene phase = 5.6 × 10−6 m3/s = 1.24 × 10−3 m3/m2s. inlet benzene phase concentration, CB1 = 0.0040 kmol/m3. outlet benzene phase concentration, CB2 = 0.0115 kmol/m3. Determine the overall transfer coefficient and the height of the transfer unit.
Kba= 7.66 × 10−4 kmol/sm3 (kmol/m3)
HOB = 1.618 m
