Exercise 04 ENG

Pagina 1

Chemical Processes and Technologies (Prof. Laura Pellegrini) Introduction to the use of Aspen Hysys® 1. Simple flash A mixture of propane, i -butane, n-butane and n -pentane at 20°C and 4 bar , having the composition reported in the table below, is fractionated in a flash-drum with a degree of vaporization α=V/F=0.6. Compute the temperature of the flash -drum, the compositions of the outgoing vapor and liquid streams and the thermal power required to perform the separation. Select the Antoine equation first and then repeat the calculations using the Peng-Robinson Equation of State. T, P F, zFi V, yi L, xi Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta” POLITECNICO di MILANO Component zF TNB [K] C3 0.25 231.1 i-C4 0.15 261.3 n-C4 0.32 272.7 n-C5 0.28 309.2 2. Adiabatic flash A mixture of propane, i -butane, n-butane and n -pentane at the temperature of 20°C and having the same composition as the one in the previous exercise is expanded through a valve from its bubble pressure to 1.2 bar and it is then fed to a flush-drum. Determine: 1. the pressure of the mixture before the valve; 2. the temperature of the flash-drum; 3. the degree of vaporization, α; 4. the compositions of the vapor and of the liquid streams leaving the flash -drum, considering that the operation is adiabatic. Select the Antoine equation first and then repeat the calculations using the Peng-Robinson Equation of State (PR EoS). T, P F, zFi V, yi L, xi 3. Multicomponent distillation A liquid mixture at the bubble point containing 4 mol% of n-pentane, 40 mol% of n-hexane, 50 mol% of n-heptane and 6 mol% of n-octane is fractionated in a standard plate distillation column, operat ed at atmospheric pressure. Using the Soave -Redlich-Kwong Equation of State (SRK EoS) and a dopting a…