You are to design a packed column to absorb C02 from air into fresh, dilute-caustic solution. The entering air contains 3 mol% C02, and a 97% recovery of C02 is desired. The gas flow rate is 5,000 ft3/min at 60°F, 1 atm. It may be assumed that in the range of operation, the equilibrium curve is Y* = 1.75X, where Y and X are mole ratios of C02 to carrier gas and liquid, respectively. A column diameter of 30 in. with 2-in. Intalox saddle packing can be assumed for the initial design estimates. Assume the caustic solution has the properties of water. Calculate:

(a) The minimum caustic solution-to-air molar flow rate ratio.

(b) The maximum possible concentration of C02 in the caustic solution.

(c) The number of theoretical stages at LIV = 1.4 times minimum.

(d) The caustic solution rate.

(e) The pressure drop per foot of column height. What does this result suggest?

(f) The overall number of gas transfer units, NoG,

(g) The height of packing, using a KGa of 2.5 lbmovh-ft3-atm.