Noor Ahmad · Thomas Deskins · Lily Li · Shiv Patel Separations Unit-Ops Noor Ahmad · Thomas Deskins · Lily Li · Shiv Patel

Outline Types of Distillation Column Unit-Ops Industrial example Shortcut Distillation SCDS (Simultaneous Correction Distillation) Tower Column Tower Plus Batch Distillation Industrial example Running a Column in ChemCad Stream Reports & Plots

Shortcut Distillation Used only for educational purposes Not used by Industry Not a rigorous column Fenske-Underwood Method used Rough Estimates for Theoretical number of stages, Optimal feed location, Rmin, and fractional recoveries, etc.

SCDS Distillation Simultaneous Correction Distillation System Non-ideal (activity coefficients, reactivity, etc) Packed column Models real behavior Uses thermodynamics to calculate mass and energy balances

Tower Column Uses the inside-out rigorous method for multistage VLE When computational power was limited, this was used more often than SCDS distillation Requires less iterations and converges faster

Tower Plus Also uses the inside-out rigorous method Allows for complex columns This model is very difficult to converge and is often only used in petroleum and refining applications

Which Distillation Column to Choose?

Industrial Example Plant operated by MOL Group, Hungarian Multinational Oil and Gas Company Located in Algyõ, Hungary Gas Distillation of Crude Oil The distillation products are Propane, Propane-Butane mix, iso-Butane, normal-Butane, iso-Pentane and normal-Pentane. These are drawn off as top/bottom products from different columns in each train. The quantity and quality specification for each of these product streams changes with demand. Trays Inside this tower and the lightweight gases move to the top Image from: http://igcsetuition.blogspot.com/ Image from: emersonprocess.com

Example/Demo

Step 1: Open Workspace, Select Components

Step 2: Set Units and Flowsheet

Step 3: Run Flowsheet and Specify Recovery.

Step 4: Stream and Unit Op Reports

Stream Report

Unit-Op Report & Plots

References http://home.anadolu.edu.tr/~skaytako/web_malzemeleri/DISTILLATION%20CO NVERGENCE.pdf http://web.thu.edu.tw/g96310005/www/3_Separators.pdf http://www2.emersonprocess.com/siteadmincenter/PM%20DeltaV%20Documen ts/ProvenResults/OilGasRefining/RES_OG_MOL_Algyo_APC_Final_7-11.pdf

Questions