If the column uses sieve plates, what column diameter is required for the absorber in Problem 12.D16? Operate at \(75 \%\) of flood. Use \(0.6096 \mathrm{~m}\) tray spacing. Assume \(\eta=0.85\). The density of liquid ammonia is approximately \(0.61 \mathrm{gm} / \mathrm{ml}\). Assume that nitrogen is an ideal gas. Note that you will have to extrapolate the graph or the equation for 24 -in. tray spacing to find \(\mathrm{C}_{\mathrm{sb}}\). Since surface tension data are not reported, assume that \(\sigma=20\) dynes \(/ \mathrm{cm}\). Watch your units!

Data From Problem 12.D16

Argon and methane are absorbed from nitrogen into liquid ammonia at 252.3 \(\mathrm{K}\) and \(175.0 \mathrm{~atm}\) in an ammonia plant. Feed rate of gas is \(100.0 \mathrm{kmol} / \mathrm{h}\). Feed gas contains \(0.020 \mathrm{~mol} \% \mathrm{Ar}\) and \(0.130 \mathrm{~mol} \%\) methane. Outlet gas contains \(0.0008 \mathrm{~mol} \%\) methane. Entering liquid ammonia is pure. Operate with L/V = 26.0. Assume \(\mathrm{L}\) and \(\mathrm{V}\) flow rates are constant. Equilibrium data: partial pressure methane atm \(=3600.0 \times\) (methane mole fraction in liquid); partial pressure argon \(\mathrm{atm}=7700.0 \times\) (argon mole fraction in liquid) (Alesandrini et al., 1972).

a. Find the outlet mole fraction of methane in the liquid.

b. Find the number of equilibrium stages required.

c. Find the outlet mole fraction of argon in the gas.