Final answer:
The student's question requires using Raoult's law and the Peng-Robinson equation to calculate vapor pressures in order to determine the liquid fraction and phase compositions in a flash drum separation of a 50 mol% propane and n-butane mixture at 37°C and 0.6 MPa.
Step-by-step explanation:
The flash drum separation involves determining the fraction of liquid that exits the drum and the composition of the exiting phases when a 50 mol% mixture of propane and n-butane is subjected to isothermal conditions at 37°C and 0.6 MPa pressure. This calculation requires the use of Raoult's law and the Peng-Robinson equation to calculate vapor pressures for the given conditions. Two scenarios are considered:
- Ideal mixtures assumption using Raoult's law, where the mole fractions in liquid and vapor phases are used to calculate the total vapor pressure and composition of the vapor phase.
- Calculation of saturated vapor pressures for each component using the Peng-Robinson equation and using Raoult's law to approximate the behavior of the vapor-liquid equilibrium.
To answer the specific question we need to perform these calculations, but it is important to note that without the actual Peng-Robinson parameters or computational tools to carry out these calculations, providing a numeric answer would be speculative. Generally, the approach involves setting up material balances around the drum, calculating the equilibrium constant for each component, and then solving the equations iteratively until a convergent solution is found.