Experiment - Simulation of a Distillation Column PDF

Experiment No. 08 Simulation of a Distillation Column Objective Develop a simple process flow sheet to estimate distillate and bottom composition of a distillation column Problem statement 100 kmol/h of an equimolar mixture of benzene and toluene at 70oC and 1 atm pressure...

Experiment No. 08 Simulation of a Distillation Column Objective Develop a simple process flow sheet to estimate distillate and bottom composition of a distillation column Problem statement 100 kmol/h of an equimolar mixture of benzene and toluene at 70oC and 1 atm pressure is to be separated by staged distillation column. A reflux ratio of 3 is used. Composition of benzene in the distillate should be 99% (by mol) toluene in the bottom should be 99% (mol). A total condenser and reboiler, both at 1 atm pressure are used. Determine the actual no. of stages, minimum reflux ratio and the minimum no. of stages for the operation. DWSIM Blocks Used Shortcut Column Procedure 1. Start a new DWSIM Simulation (DWSIM VER 5.1 - CLASSIC UI). Click on “New steady state Simulation” as a template for new simulation 2. The simulation configuration window will be opened. Add the two components required for simulation - Benzene and Toluene. Ensure that all the components are added from same property package. Example: All the 2 components are selected from Chemsep database. Click “Next” button. 3. Select and add the property package and click “Next”. Add the default flash algorithm for the simulation. Click “Next”. 4. The flowsheeting section of simulation window will be opened. Drag and drop the Material stream from the object palette. Rename it as “Feed”. This serves as input stream. 5. On clicking the “Feed” stream, general information about the block will be displayed on the left of the screen. Specify the feed compositions, flow rate, temperature and pressure for the inlet streams. Once composition and flow rate are specified for the inlet streams, the color of stream turns blue. Specification for the inlet stream 29 | P a g e  Quantity Value Temperature, (oC) 70 Pressure, (atm) 1 Molar Flow rate (kmol/h) 100 Composition (mole fraction) Benzene: 0.5 Toluene: 0.5 6. Add two more Material streams i.e. Drag and drop them into the flow sheet. Rename them as “Distillate” and “Bottoms”. These serves as output streams. 7. Add two energy streams, one is for condenser duty (C-Duty) and the other is for re-boiler duty (R-Duty). 8. Below the Unit Operation tab, locate the “Shortcut Column” block. Drag and drop into the flow sheet. Rename it as “DC”. 9. Click on “DC” block, the general information about the block is displayed on the left of the screen. Provide calculation parameters as shown in the screenshot given below 30 | P a g e 10. Under Column configuration select “connections” tab. Click the dropdown button and give appropriate connections. If all the connections are given correctly, the blocks will turn blue. 11. Run the simulation by pressing “Solve flow sheet” button on the top corner of the screen. 12. To analyze/display the results, select on “Master property table” icon on the tool bar. A box will appear which is double clicked to modify it further. Select the streams which have to be shown in output and click “OK”. The property table will be opened showing all the results as shown in the figure below. Results 31 | P a g e Self-Learning Exercises 1. Simulate the column with feed given at (i) Stage 5 (ii) Stage 15 of the distillation column. Make inferences appropriately. 2. Simulate the column at reflux ratio of 2. Discuss your results 32 | P a g e