The cooled exhaust gas from a reactor that makes silicon by the chemical vapor deposition of trichlorosilane contains 8.0 mole% anhydrous HC1 vapor and 92.0 mole % hydrogen (H₂) gas at 25°C. The total gas flow rate is 1.25 kgmole/h. It is desired to scrub out the HC1 vapor from this gas stream by a gas absorption process using pure water as the inlet solvent within a counter current packed tower. The desired outlet concentration of HCI in the gas is only 0.10 mole%. Although HCI is highly soluble in water, the mole fraction of HC1 in the exiting liquid stream is kept at 2.0 mole% to avoid the handling of a highly corrosive liquid. At this composition, the liquid flow rate is comfortably above the minimum solvent flow rate. The tower is maintained at 1.0 atm and 25°C. Equilibrium distribution data for HC1-water at 1.0 atm total system pressure and 25°C is provided in table below. 

a. What is the operating solvent flow rate fed to the packed tower? 

b. Provide a plot of y_A vs. x_A for the equilibrium line and the operating line. What is the HC1 mole fraction in the outlet liquid at the minimum solvent flow rate?

c. What are the overall mass-transfer driving forces (y_A €“ y^*_A) at the top and bottom of the tower, and the log-mean driving force at the conditions of operation? 

d. A tower shell of 0.50 m diameter is available for use. Ceramic Intalox saddle packing of 1.5 inch nominal size is also available. At the conditions of operation given above, will the tower flood? What is the calculated pressure drop per unit depth of packing? The density of the outlet liquid is 1033 kg/m³, and the viscosity of the outlet liquid is 1.2 cP, and the molecular weight of HC1 is 36.5 g/gmole. 

Equilibrium distribution data for HCI-water at 20°C and 1.0 atm (A = HC1):

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0.210 0.243 0.287 0.330 0.353 0.375 0.400 0.425 XA 0.0523 0.0023 0.0215 0.0095 0.0852 0.135 0.203 0.322 УА