Question

Question 1 hydrooarbon A mixed stream enters a flash drum at 500 kPa and 313 K. The flowrate of the stream is 325 kmol/h. The composition of the feed stream is provided in Table 1. It can be assumed that equilibrium is reached in the drum. The values of Ki can be found using Figure 1. Do at least three iterations until the same value is achieved. Table 1: Feed flowrates for the hydrocarbon stream Component Feed (kmol/h) methane 50 ethane 75 110 propane n-pentane 90 Total 325 1.1. Draw a schematic diagram depicting the process, showing all streams entering and leaving the flash drum. (2) 1.2. Determine the mole fraction of the feed that enters as a vapour. (20) 1.3. Determine the composition of the liquid and vapour product streams. (4) [26 Marks]

Answer 1

PHASE SEPARATION IS NO POSSIBLE AT 313K . TEMPERATURE SHOULD MUST BE HIGHER THAN 80 DEG C OR 353 K

Please Find the solution below. AT the given temp. entire feed would be in Liquid phase. I have solved this using Excel sheet.

Simple Multi-Component Distillation 3750.3 mm H Pressure (Thiele & Geddes Method) Read Properties from Databank CheCalc.com Step 1 Tag No. T-101 Chemical Engineering Calculations Feed Column Mol Boiling Description 6-Jan-16 Comp. Date Fraction Temp Average User Input Checale Mols By S.no MW 15385 135 # 20.8 15.224 7.8 1 43 -17.16 7 30.07 Column Details Feed Composition (Mols/Mol Fraction) 50.9 2 15.6637 1511.42 0.23077 220.47 TRUI Feed mols 50.0 TRUE F 325.00 METHANE 15.726 1872.46 -25.16 110 44.097 0.33846 274.94 93.1 Distilate 200.00 mols 75.0 101.3 C ETHANE 15.8333 2477.07 -39.94 90 72.151 0.27692 365.71 TRUE R 2 00 Reflux Ratio PROPANE 110.0 18.3036 3816 44 -46.13 18.015 0 TRUI 00 Number of Stages 0.00 50 25 90.0 6 1E+21 FALSE N-FENTANE WATER 0.0 -21 Total FALSE 5.000 Bar Abs Top Pressure 1E+21 0.00 FALSE 0.00 Feed Temperature IC 1E+21 FALSE 80.00 0 325 266.1 Check Feed Condition Step 2 Result 95.50 Bar Abs Feed Bubble Bubble Point Pressure Top Botton Dew Phase Temperature _ L V int Ki Abs 106.67 43.27 125.00 mol/h Mixture exists as Superheated Vapor 'C S.no Flow Mol Fraction METHANE ETHANE PROPANE mol/h 200.0 325.0 1 46981.52 5.0E-07 81.428 Status 2 Flash Required Vapor Fraction (Guess) Yi xi FALSE 16300.57 3.3E-06 18.835 0.2500 0.0000 0.3750 0.0000 Feed 10 0.1538 Reflux Ratio 2.00 7583.74 1.5E-05 5.975 765.58 0.2308 1.0E-04 0.737 0.095 0.00 0.0E+00 0.3750 0.2800 0.3385 325 5

Check Feed Condition Step 2 Result Bubble Bubble Point Pressure 95.50 Bar Abs Feed Top Bottom Dew Phase L Ki Dew Point Pressure 11.20 Bar Abs Point Point Tor 200 mol/h Temperature S.no exists as Superheated Vapor 206.0 5. OF-07 6981 52 325.0 mol/h 81.428 Mol Fraction METHANE ETHANE PROPANE N-PENTANE WATER 16300.571 Flash Required Yi xi FALSE 3.3E-06 18.835 0.2500 00000 0.3750 0.0000 0.3750 0.2800 0.0000 0.7200 mol/h 0.0000 0.0000 5.975 0.1536 Reflux Ratio 2.00 7583.74 1.5E-05 Vapor Fraction (Guess) Feed 0.2308 765 58 1.0E-04 0.737 0.095 0.3385 325 0.OE+00 0.2769 0.00 0.0E+00 0.000 0.00 ELOO 0.00 0.0E+00 0.000 0.00 0.OE+00 0.000 71631.40 8400.22 Bottom 125 mol/h Feed Flash Calculation tion Iteration METHANE 0 0557 0.0000 S.no FIT) FIT) FIT) F(T) F(T) F(T) FT PROPANE N-PENTANE WATER 0.3368 5196 0 1920 0.0000 04509 0.808C