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Unformatted text preview: Homework 6 Problem 3 HYSYS™ Distillation Column Processing and
Design Using the Full Design Column Method
20 points possible due Monday October 10, 2011 Grader: Israel Problem Statement: A bubble cap distillation column with an 18 inch tray spacing is to be used to separate a biphenyl/fluorene mixture. The multicomponent feed enters the column at a temperature of 536oF and pressure of 31.17 psia with the composition shown below: m , lb/hr
m , lb/hr
Component Toluene 44.965 m‐Cresol 13.085 Naphthalene 204.95 Fluorene 171.04 Biphenyl 2,596.1 Phenanthrene 137.06 o‐Cresol 22.493 m‐Terphenyl 441.96 p‐Cresol 36.010 It is desired to obtain 98% biphenyl recovery in the distillate with a column pressure drop of 23.435 psia. Determine the distillate and bottoms concentrations and flow rates, number of trays, optimum feed location, reflux ratio, and the column diameter. Method of Solution: Use the solution from the Shortcut Distillation Column example to simulate the design in a full Distillation Column in HYSYSTM to separate the feed mixture. Solution: 1) Open HYSYSTM and start a new case. 2) The Simulation Basis Manager window will open. Click the Fluid Pkgs tab, and click Add. 3) Select the appropriate property package. Since the process streams are hydrocarbon and phenol mixtures, select the PRSV equation of state. Page 1 of 9 4) Click View next to the Component List Selection box. 5) Add the process components. When the Selected Components List is complete, close the Component List View and Fluid Package windows. 6) Click Enter Simulation Environment. 7) Click on the Distillation Column icon on the Object Palette, and click again in the PFD workspace to place the column in the PFD. Page 2 of 9 8) Double‐click on the column you just placed on the PFD to open the column window. The Distillation Column Input Expert window will allow you to specify the column in a systematic way (To turn off/on Input Expert go to Tools / Preferences, under Options on the Simulation Tab, select/deselect the check box Use Input Experts). The first page allows you to rename your column, specify the connecting material and energy streams. Specify a feed stream, distillate product stream, bottoms product stream, condenser duty stream, reboiler duty stream, number of stages, and feed location as calculated from the Short Cut Column. 9) Keep the default selection Once‐through regular Hysys reboiler. Page 3 of 9 10) Click Next. Enter a Condenser Pressure and Reboiler Pressure of 7.735 psia. Leave the Condenser Pressure Drop as 0 kPa. 11) Click Next. Temperature estimates are not needed, though they do help to decrease iteration time. Click Next. Enter a Reflux Ratio of 0.956 with a Mass Flow Basis. Click Done. Page 4 of 9 12) We still need to input our feed stream conditions. Close the distillation column input window and open the feed stream. Enter the feed temperature and pressure. 13) Click on the Composition option. Click the Basis… button and change the compositions basis to Mass Flow. Input the given mass flow rate of Toluene and press ENTER. Enter the flow rate of each component; be sure that each is input with the correct units. When all component flow rates have been entered, click OK. Page 5 of 9 14) Close the feed stream and double click on the distillation column to open the input window. Open the Monitor section by selecting it from the menu on the left side of the column window. Page 6 of 9 15) The problem statement specifies a biphenyl recovery of 98%. To add this specification, click the Add Spec… button, select Column Component Recovery, and click Add Spec(s)…. 16) Select D @COL1 (distillate) for the draw stream. Specify 0.98 recovery of Biphenyl. Close the specification window. 17) Unclick the Active check box for the Distillate Rate and click the Active check box for the Comp Recovery. The column should automatically start running. If it does not automatically run, click the Run button. Page 7 of 9 18) Notice that the status bar has turned green and displays “Converged”, indicating that the column has converged. Click on the Performance tab to view the results. Change the basis to Flow in the right hand corner of the Performance tab. The Distillation Column calculates a product that is 84% biphenyl. The problem statement specifies a 98% biphenyl recovery in this process 14.59 lbmol/hr were recovered from 14.89 lbmol/hr fed. Page 8 of 9 Results/Considerations: The Distillation Column calculates a product that is 83.7% biphenyl with a reflux ratio of 0.956. The Short Cut Column calculated a product that was 84.0% biphenyl also with a reflux ratio of 0.956. Page 9 of 9 ...
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