Unit Operations Laboratory Distillation Analysis Seminar Super Team 2005 Monday, December 5, 2005 2:30 PM
Presentation Overview Introduction Distillation Safety Operating Procedure Composition Flow Chart Experimental vs. Predicted Results Sensitivity of CHEMCAD Conclusions
Sensitivity Study Using CHEMCAD SCDS Column How to separate Ethanol from Propanol ?
Overview Fixed Parameters for the Study Purpose CHEMCAD SCDS Process Flow Diagram Variables Results for Feed Tray at 1 Results for Feed Tray at N/2 Results for Feed Tray at N
Fixed Parameters for the Study Specifications: Adiabatic distillation column Ideal equilibrium trays Feed flow rate = 3.5 mol/min Feed composition, xF = 0.50 mole fraction ethanol Feed temperature = 50 ºC Feed pressure = 1 atm Reflux temperature = 50 ºC Reboiler duty = 1300 W (Note the number of stages used in CHEMCAD is actually N+2 to account for the condenser and reboiler, where N is the number of trays.)
Purpose To conduct an in depth study on the effects of the following variables on the mole fractions of ethanol in the distillate and bottoms flow streams: Reflux Ratio Number of Trays
CHEMCAD SCDS Process Flow Diagram Fixed Parameters for the Study Reflux Properties Temperature = 50 ºC Feed Stream Flow Rate = 3.5 mol/min Ethanol Composition = 0.5 mole fraction ethanol Temperature = 50 ºC Pressure = 1 atm Reboiler Properties Reboiler Duty = 1300 W
Variables The effect of independent variables: Reflux ratio Number of trays 1, 2, 4, 8, and 16 Feed tray location Top = 1 , Middle = N/2, Bottom = N On the dependent variables: xD, the mole fraction of EtOH in the distillate, and xW, the mole fraction of EtOH in the bottoms.
Results for Feed Tray at 1 Reflux N = 1 N = 2 N = 4 N = 8 N = 16 Ratio xD xW 0.5 0.686 0.433 0.706 0.426 0.716 0.422 0.717 0.421 1 0.699 0.452 0.448 0.725 0.446 0.726 0.445 1.5 0.705 0.463 0.723 0.460 0.730 0.458 0.731 2 0.710 0.470 0.467 0.733 0.466 0.734 2.5 0.713 0.474 0.729 0.472 0.736 0.471 3 0.715 0.478 0.476 0.737 0.475 0.738 3.5 0.480 0.732 0.479 0.739 4 0.718 0.483 0.481 0.740 4.5 0.719 0.484 0.741 5 0.486 0.735 0.485 5.5 0.720 0.487 0.742 6 0.721 0.488 0.743 6.5 0.489 7 0.722 7.5 0.490 0.744 8 0.491 8.5 9 0.492
Distillate for Feed at N = 1
Bottoms for Feed at N = 1
Results for Feed Tray at N/2 Reflux N = 1 N = 2 N = 4 N = 8 N = 16 Ratio xD xW 0.5 0.686 0.433 0.706 0.426 0.758 0.406 0.788 0.395 0.794 0.392 1.0 0.699 0.452 0.717 0.448 0.789 0.430 0.849 0.414 0.882 1.5 0.705 0.463 0.723 0.460 0.805 0.444 0.883 0.429 0.940 0.418 2.0 0.710 0.470 0.726 0.467 0.816 0.454 0.903 0.440 0.967 2.5 0.713 0.474 0.729 0.472 0.823 0.461 0.915 0.449 0.979 3.0 0.715 0.478 0.731 0.476 0.828 0.466 0.923 0.455 0.984 3.5 0.716 0.480 0.732 0.479 0.831 0.929 0.988 4.0 0.718 0.483 0.733 0.481 0.834 0.473 0.933 0.464 0.990 0.459 4.5 0.719 0.484 0.734 0.837 0.475 0.937 0.991 5.0 0.486 0.735 0.485 0.838 0.477 0.939 0.992 5.5 0.720 0.487 0.736 0.840 0.942 0.993 0.469 6.0 0.721 0.488 0.841 0.943 6.5 0.489 0.737 0.843 0.482 0.945 0.994 7.0 0.722 0.844 0.946 7.5 0.490 0.845 0.947 8.0 0.491 0.738 0.948 0.995 8.5 0.846 0.949 9.0 0.492 0.847
Distillate for Feed at N/2
Bottoms for Feed at N/2
Results for Feed Tray at N Reflux N = 1 N = 2 N = 4 N = 8 N = 16 Ratio xD xW 0.5 0.686 0.433 0.732 0.416 0.758 0.406 0.763 0.404 0.764 1.0 0.699 0.452 0.767 0.435 0.826 0.420 0.858 0.412 0.864 0.410 1.5 0.705 0.463 0.786 0.448 0.866 0.926 0.421 0.957 0.415 2.0 0.710 0.470 0.797 0.457 0.889 0.442 0.960 0.431 0.995 0.426 2.5 0.713 0.474 0.805 0.904 0.450 0.974 0.441 0.999 0.438 3.0 0.715 0.478 0.811 0.467 0.913 0.456 0.982 0.446 3.5 0.716 0.480 0.816 0.471 0.920 0.461 0.986 0.454 1.000 0.453 4.0 0.718 0.483 0.819 0.925 0.465 0.988 0.459 0.458 4.5 0.719 0.484 0.822 0.476 0.929 0.468 0.990 0.462 5.0 0.486 0.824 0.932 0.991 0.466 5.5 0.720 0.487 0.935 0.473 0.992 0.469 6.0 0.721 0.488 0.827 0.482 0.937 0.475 0.472 6.5 0.489 0.829 0.938 0.477 0.993 7.0 0.722 0.830 0.940 7.5 0.490 0.831 0.485 0.941 0.479 0.994 8.0 0.491 0.832 0.942 0.481 8.5 0.723 0.943 9.0 0.492 0.833 0.944
Distillate for Feed at N
Bottoms For Feed at N