6.79. A two-unit process is used to separate H2S from a gas containing 96% H2 and 4% H2S by volume. The H2S is absorbed in a solvent, which is then regenerated by air in a stripping column. The Henry's law constant for the absorption of H2S in the solvent at 0°C is 22 atm/mole fraction. G4 Air + H₂S A lo G3 Clean air G₂ ot Product gas Som doun vilmo rbs (G₁ Data on Process Streams STRIPPER 40°C, 1.0 atm 9gniwo G₁: 100 mol/h 40°C 96% H2, 4% H2S, 1.8 atm G2: 99.9% H2, 0.1% H2S G3: 200 mol air/h L₁ HEATER ovloazib o ABSORBER 0°C, 1.8 atm. (12) G4: 40°C, 1 atm 0°C L₁: 0.200 mole% H₂S L2: Assume at equilibrium with G₁ at 0°C Feed gas H₂+ H₂S otizo (a) Briefly explain in your own words the functions of the three process units. Include in your explanation the purpose of the air in the stripper and the reason the stripper operates at a higher temperature than the absorber. (b) Calculate the molar flow rate of pure solvent and the volumetric flow rate of the gas at G4, neglecting evaporation of solvent in both columns. (See flowchart.) Exploratory Exercise-Research and Discover sby (c) The objective of the process described above is to produce purified hydrogen. However, in doing em brupt so the process also generates an effluent stream containing H2S. Identify at least three concerns with simply releasing this stream into the air. Suggest an add-on to the process that allays as many of these concerns as possible. Calculate the mass per 100 mol of G₁ of any reactant required by the add-on. Identify any new concerns created by the add-on.