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A wetted - wall column is used to recover ammonia from flue - gas by absorption with water. Unfortunately, the gas phase contains significant amount

A wetted-wall column is used to recover ammonia from flue-gas by absorption with water. Unfortunately, the gas phase contains significant amount of CO2 and other gases which can also dissolve in water. Thus, a solid polymer membrane (3-mm thick) is used in between the liquid and gas phase to selectively permeate only NH3(component A). The bulk gas and liquid phase compositions are measured to be 6.0(yA,b) and 0.1(xA,b) mole% NH3, respectively. (40 points) Let the mole fraction of NH3 in solid polymer phase be zi akin to xi and yi in liquid and gas phase respectively. The equilibrium relation between gas and polymer phase is given by z =0.8*y and between liquid and polymer phase by z =2*x. Mass transfer through a membrane is given by the permeability equation: N =-P*(dz/dl)2 where, N is the molar flux of the diffusing species, P is the permeability (=3*10-6 kmol/m.s), and l is the thickness of the membrane. The temperature is 300K and the total pressure is 1 atm. 80% of the total resistance to mass transfer is found to be in the solid polymer phase while resistance to mass transfer is negligible in the gas phase. Calculate a) steady-state flux of ammonia in the column (NA) b) overall mass transfer coefficient based on gas phase (KY), c) individual film coefficients (kx, ky, kz) and d) interfacial concentrations (xA,i, yA,i, zAG,i, zAL,i). zAG,i and zAL,i refer to the interfacial concentrations of ammonia between the polymer and the gas, and the polymer and water respectively. Interfacial concentrations lie on the equilibrium lines. (Hint: the film coefficient for the solid polymer phase is defined as follows, kz = NA/(zAG,i zAL,i))

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