A pilot-scale tower packed to a height of 6.0 ft with 5/8- inch ceramic Raschig rings is used to study the absorption of carbon disulfide (CS₂, solute A) from nitrogen gas (N₂) into a liquid absorbent solution at 24°C. The diameter of the tower is 0.50 ft. An inlet gas stream of total molar flow rate 2.0 lbmole/h and composition of 3.0 mole% CS₂ enters the bottom of tower. The outlet gas composition of CS₂ is 0.50 mole%. Pure solvent (molecular weight of 180 g/mole) of total molar flow rate 1.0 lbmole/h enters the top of the tower. The composition of CS₂ in the outlet liquid is 4.8 mole%. Over the concentration range of operation, Henry’s law is valid with P_A = Hx^*_A, where H = 0.46 atm at 24°C. The total system pressure in the tower is 14.7 psig (gage pressure). Additional data: gas density, ρ_G = 0.16 lbm/ft³; liquid density, ρ_L ˆ 75 lb_m/ft³; liquid viscosity, µ_L = 2.0 cP. 

a. Determine the minimum solvent flow rate AL_s,min. 

b. Based on the conditions of operation, estimate the K_ya required for the packed-tower height of 6.0 ft. 

c. At the conditions of operation, it can be calculated that the tower operates at 26% of the flooding velocity (G' = 0.26 G'_f) . Recommend a new size of ceramic Raschig ring packing, which will bring the gas velocity within the range of 40–45% of the flooding velocity at the fixed tower diameter of 0.5 ft.