An equimolar liquid mixture of n-pentane and n-hexane at 80C and 5.00 atm is fed into a flash evaporator at a rate of 100.0 mol/so When the feed is exposed to the reduced pressure in the evaporator, a substantial amount is vaporized. The temperature in the tank is maintained at 65C by adding heat. The vapor and liquid phases, which are in equilibrium with each other, are separated and discharged *Computer problems. 419 as separate streams. The liquid product stream contains 41.0 mole% pentane. A flowchart and an inlet-outlet enthalpy table for the process are given below. Vapor product 65'C, Po(atm) References: P(I, 65C), H(I, 6SOC) Substance nin Hm n out Hout P(l) na Ha nc He P(v) - - nd Hd H(I) nb Hb ne He LiqUid product H(v) - - nf HI 65'C, Po(atm) Xp =0.41 mol P(I}/mol P = pentane .L yp[mol P(v)/molj H = hexane 100 molls, liquid FLASH EVAPORATOR 50 mole% P 50 mole% H -+ -Q(kW} 80C. 5.0 atm Student Workbook Encyclopedia Equipment evaporator reactor, Encyclopedia Equipment condenser Encyclopedia Equipment dryer (a) Using Raoult's law for vapor-liquid equilibrium calculations, calculate (i) the system pressure, Po(atm), (ii) the mole fraction of pentane in the vapor product, yp, (iii) the volumetric flow rate of the vapor product, V(Lls), and (iv) the fractional vaporization of pentane,f(mol vaporized/mol fed). (b) Determine values for all the it's and fJ's in the enthalpy table and calculate the required rate of heat addition to the evaporator, Q(kW)
Problem 8.51An equimolar liquid mixture of n-pentane and n-hexane at 80°C and 5.00 atm is fed into aflash evaporator at a rate of 100.0 mol/s. When the feed is exposed to the reduced pressurein the evaporator, a substantial amount is vaporized. The temperature in the tank ismaintained at 65°C by adding heat. The vapor and liquid phases, which are in equilibriumwith each other, are separated and discharged as separate streams. The liquid productstream contains 41.0 mole% pentane. A flowchart and an inlet-outlet enthalpy table for theprocess are given below.(a) Using Raoult's law for vapor-liquid equilibrium calculations, calculate (i) the systempressure, P (atm), (ii) the mole fraction of pentane in the vapor product, y , (iii) the 0 pvolumetric flow rate of the vapor product, V(L/s), and (iv) the fractional vaporization ofpentane,f(mol vaporized/mol fed). (b) Determine values for all the ns and ’s in the enthalpy table and calculate the requiredrate of heat addition to the evaporator, Q(kW) Step-by-step solution Step 1 of 8 ^Draw a flowchart for the flash evaporator system.Here, P stands for pentane and H stands for hexane.(a)Calculate the vapor pressure of pentane in the exit vapor stream using the Antoine equation.Look up the Antoine constants in table B.4. For n-pentane, A is 6.84471, B is 1060.793 and C is231.541.\n Blog10 P = A T + C B A T + C pP* = 10 6.84471 65°C + 231.541 = 10 =Calculate the vapor pressure of hexane in the exit vapor stream using the Antoine equation.Look up the Antoine constants in table B.4. For n-hexane, A is 6.88555, B is 1175.817 and C is224.867. Blog10H = A T + C A B PH = 10 T + C 1175.817 = 10 6.88555 65°C + 224.867 =
