We plan to treat \(150.0 \mathrm{kmol} / \mathrm{h}\) of water that is saturated with carbon tetrachloride (the \(\mathrm{CCl}_{4}\) is at the solubility limit shown in Table \(12-2\) ) at \(25.0^{\circ} \mathrm{C}\) and a pressure of 0.96 bar by stripping with pure air at \(25.0^{\circ} \mathrm{C}\) and 0.96 bar (parts

a, b, c). Remove \(90.0 \%\) of the \(\mathrm{CCl}_{4}\). Assume the Henry's law constant and solubility of \(\mathrm{CCl}_{4}\) do not depend on pressure.

Table 12-2

a. What is the minimum value of gas flow rate \(\mathrm{V}_{\min }\) ?

b. If we operate at \(\mathrm{V}=2.5 \times \mathrm{V}_{\text {min }}\), what is the value of \(\mathrm{V}\), how many stages are needed, and what is the outlet gas mole fraction of \(\mathrm{CCl}_{4}\) ?

c. If we operate at \(\mathrm{V}=1.10 \times \mathrm{V}_{\text {min }}\), what is the value of \(\mathrm{V}\), how many stages are needed, and what is the outlet gas mole fraction of \(\mathrm{CCl}_{4}\) ?

d. Your boss wants to know what the minimum gas flow rate will be if the stripper is operated under a vacuum at 0.5 bar and \(25.0^{\circ} \mathrm{C}\).

e. If we operate at 0.5 bar and \(25.0^{\circ} \mathrm{C}\) and \(\mathrm{V}=2.5 \times \mathrm{V}_{\text {min }}\), what is the value of \(\mathrm{V}\), how many stages are needed, and what is the outlet gas mole fraction of \(\mathrm{CCl}_{4}\) ?

f. If we operate at \(0.5 \mathrm{bar}\) and \(25.0^{\circ} \mathrm{C}\) and \(\mathrm{V}=1.10 \times \mathrm{V}_{\min }\), what is the value of \(\mathrm{V}\), how many stages are needed, and what is the outlet gas mole fraction of \(\mathrm{CCl}_{4}\) ?
g. Explain how \(\mathrm{N}\) can be the same in parts \(\mathrm{b}\) and \(\mathrm{e}\) at different pressures, but \(\mathrm{y}_{\text {out }}\) is larger at the lower pressure.
h. Approximately, what is lowest pressure that can be used if temperature is \(25.0^{\circ} \mathrm{C} ?\)

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TABLE 12-2. Henry's law constants for Eq. (12-3) and solubilities for chlorinated compounds in water at 25.0C and 1.0 atm (Yaws et al., 2005) Compound Carbon Chloroform Dichloro- Vinyl tetra- CHCl3 chloride CCl4 1,2,3,- 1- 1-Chloro- methane chloride Trichloro-Chloro- naphthalene CH2Cl2 C2H2Cl propane heptane C 10H7Cl C3H5Cl3 C7H15Cl atm H 1589.36 211.19 137.00 1243.84 23.78 2130.28 10.96 mole frac. Solubility, 93.68 1190.1 ppm (mol) 4175.4 778.9 213.99 1.8196 2.48