Question

4. In a packed-bed absorber, solvent and gas inlet flow rates are 25 kmol/h and 90 kmol/h,respectively under design conditions. Under these design conditions, solute mole fractions in the gas

at the inlet and outlet are 0.012 and 0.006, respectively. The absorber has 25 transfer units and its operating pressure is 2 bar. Assume tower is operating isothermally (note absorption is generally exothermic, but for simplicity assume isothermal operation) at 60°C under base case condition a. The solvent flowrate got decreased by 20% due to some issue with the solvent pump.What is the new outlet mole fraction of solute? b. Since the solvent pump problem cannot be solved in a while, it is decided to decrease the tower operating temperature by decreasing the solvent temperature. When the tower temperature (assume the tower operates isothermally) became 30°C, outlet mole fraction of solute becomes same as the design condition. What are the values of A and B in the Antoine Equation for the solute? Assume that the solute follows Raoult's law. Vapor pressure of the solute is given by the Antoine equation: In p* = A- B/T when P* is in bar and T is in K

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