[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-177645-105":3,"detail-sidebar-cat-1-en-105":81,"doc-detail-177645-en":126},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":74,"head_meta":76,"extra_data":78,"updated_unix":80},105,"en","dstwu-and-radfrac-distillation-models-tutorial-2","DSTWU and RADFRAC Distillation Models - Tutorial - #2","","Instructional workflow for designing a C2 splitter to achieve 95% ethylene recovery and ~99% ethylene purity in the distillate using two simulation levels in Aspen. The guide sets DSTWU operating conditions (P, RR, and component recoveries), then uses the shortcut results to initialize a rigorous RADFRAC tray-by-tray model with total condenser and specified reflux ratio. It outlines stage and feed-location sensitivity studies, including extracting molar flow rate, equilibrium stages, and feed stage location from DSTWU and configuring RADFRAC for iterative refinement.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/template/","Template",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/template/presentations/","Presentations",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/template/dstwu-and-radfrac-distillation-models-tutorial-2/177645/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/dstwu-and-radfrac-distillation-models-tutorial-2/177645.png","ImageObject",442,249,{"name":42,"@type":43},"Tawan","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/vnd.openxmlformats-officedocument.wordprocessingml.document","2026-10-25","2026-09-02",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",17,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"What design targets define the C2 splitter problem?","Question",{"text":63,"@type":64},"The design must provide 95% recovery of ethylene in the distillate with distillate purity of about 99% ethylene.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"How are DSTWU results used to initialize the RADFRAC model?",{"text":68,"@type":64},"DSTWU outputs such as total distillate molar flow rate, actual equilibrium stages, and feed stage location are used as initial guesses for RADFRAC configuration.",{"name":70,"@type":61,"acceptedAnswer":71},"Which RADFRAC setup options are required for this case?",{"text":72,"@type":64},"RADFRAC uses a total condenser and a kettle reboiler, with number of stages taken from DSTWU and distillate rate plus reflux ratio matching the DSTWU-derived values.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},177645,1788328716,{"code":4,"msg":82,"data":83},"success",[84,88,93,98,103,108,112,117,122],{"id":85,"doc_module":22,"doc_module_name":25,"category_name":29,"show_sort_weight":86,"slug":87},11,90,"presentations",{"id":89,"doc_module":22,"doc_module_name":25,"category_name":90,"show_sort_weight":91,"slug":92},12,"Resumes",80,"resumes",{"id":94,"doc_module":22,"doc_module_name":25,"category_name":95,"show_sort_weight":96,"slug":97},14,"Invoices",70,"invoices",{"id":99,"doc_module":22,"doc_module_name":25,"category_name":100,"show_sort_weight":101,"slug":102},15,"Posters",60,"posters",{"id":104,"doc_module":22,"doc_module_name":25,"category_name":105,"show_sort_weight":106,"slug":107},16,"Social Media",50,"social-media",{"id":55,"doc_module":22,"doc_module_name":25,"category_name":109,"show_sort_weight":110,"slug":111},"Forms",40,"forms",{"id":113,"doc_module":22,"doc_module_name":25,"category_name":114,"show_sort_weight":115,"slug":116},18,"Letters",30,"letters",{"id":118,"doc_module":22,"doc_module_name":25,"category_name":119,"show_sort_weight":120,"slug":121},21,"Paper Templates",5,"papers-templates",{"id":123,"doc_module":22,"doc_module_name":25,"category_name":124,"show_sort_weight":4,"slug":125},158,"General","general-158",{"code":4,"msg":82,"data":127},{"doc_id":79,"user_id":128,"nickname":42,"user_avatar":129,"doc_module":22,"category_id":85,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":130,"file_id":131,"file_url":132,"file_type":133,"file_size":134,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":135,"language":136,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":137,"faqs":138,"seo_title":139,"seo_description":12,"update_tm":80,"read_time":120},2336475104042,"https://ap-avatar.wpscdn.com/avatar/22000c4c32af1715be0?x-image-process=image/resize,m_fixed,w_180,h_180&k=1786537525561427321","ASPEN Tutorial #2\nChE 473K\nDSTWU and RADFRAC Distillation Models\nWe have been asked to design a C2 splitter that will give 95% recovery of the ethylene feed, as well as a purity of 99% ethylene in the distillate.\nThe feed conditions are as follows:\nWe will use the DSTWU model to estimate the operating conditions.  Run the DSTWU at P=18 bar, RR=3.1, and basis=100 lbmol/hr. DSTWU performs a Winn-Underwood-Gilliland shortcut design calculation for a single-feed, two-product distillation column, with a partial or total condenser.\nThen we will use these results to design a RADFRAC analysis. RadFrac is a rigorous tray to tray model for simulating all types of multistage vapor-liquid fractionation operations.  Make sure that you have a total condenser, and that you have a spec. which sets the purity of ethylene in the Distillate to 99%.\nLater we will use a sensitivity analysis to determine the optimum feed location and number of stages.  This will be accomplished by varying the number of stages from 23-35 and the feed location from 12-21, and examining the reflux ratio, reboiler duty, and condenser duty.\nOpen a new simulation, and you should be taken to the Components-Specifications form. Enter the components in the feed stream as defined at the beginning of the worksheet.\nHit the Next button, and the Methods-Specifications form should appear. Under “Method Name,” select PENG-ROB.\nHit Next twice, and select Go to Simulation environment.\nUsing the DSTWU model\nInsert a DSTWU column, one feed to the left of the column and two product streams to the right of the column in the main flowsheet space.\nConnect the feed arrow to the Feed on the DSTWU block.\nConnect the top product arrow to the Distillate arrow on top of the DSTWU block.\nConnect the bottom product arrow to the Bottoms arrow on the bottom of the DSTWU block.\nNote:  The stream numbers become important later, so make sure that they appear the same as the example picture.\nThe flowsheet should look like this:\nClick Next and the Streams-S-1-Input-Specifications form should appear.\nEnter the following values for the feed stream:\nThe Streams-S-1-Input-Specifications form should look like this:\nHit the Next button, and the Blocks-B1-Input-Specifications form should appear.\nEnter the following values:\nReflux ratio:  3.1\nLight key\nComp:\tETHYLENE\nRecov:\t0.95\nHeavy key\nComp:\tETHANE\nRecov:\t0.03\nPressure\nCondenser:  \t17.8 bar\nReboiler:  \t18.2 bar\nNote:  The recovery of 0.95 is to meet the 95% recovery of ethylene specification.  The recovery of 0.03 is to make the purity of the distillate stream approximately 99% ethylene.  This value can be calculated by doing a material balance around the column.  The value of 0.03 does not account for any of the other components going into the distillate product stream, and is therefore just an estimate.\nThe Blocks-B1-Input-Specifications form should look like this:\nSelect the Calculation Options tab and check the Generate Table block. Set the Initial Number of Stages at a value above the minimum stage count (18  will work) and the Final Number of Stages at 40.\nThe Blocks-B1-Input-Calcualtion Options form should look like this:\nHit the Next button, and ASPEN should indicate that the required input is complete.  You should save the program before pressing OK and running it.\nYou may want to turn on the mole fraction output in the Setup-Report Options-Stream form prior to running the simulation.\nRun the simulation, and check the results. We will use the results from both the Blocks-B1-Stream Results and the Blocks-B1-Results forms. The most important values to note are:\nTotal Molar Flow Rate of the distillate product stream.  This is one of the necessary inputs for the RADFRAC model.  This number is not completely correct since the 0.03 value for the Recovery specification is just an estimate.\nActual Equilibrium Stages --- this will be used as the first guess for our RADFRAC column.\nFeed Stage Location, this will also be used as the first guess for the RADFRA","cbCaieVZCT4dKCNZ","https://ap.wps.com/l/cbCaieVZCT4dKCNZ","docx",1250588,13,"English","# Problem Setup\n## DSTWU Model Setup\n## RADFRAC Model Setup\n# Sensitivity Analysis Plan","[{\"question\":\"What design targets define the C2 splitter problem?\",\"answer\":\"The design must provide 95% recovery of ethylene in the distillate with distillate purity of about 99% ethylene.\"},{\"question\":\"How are DSTWU results used to initialize the RADFRAC model?\",\"answer\":\"DSTWU outputs such as total distillate molar flow rate, actual equilibrium stages, and feed stage location are used as initial guesses for RADFRAC configuration.\"},{\"question\":\"Which RADFRAC setup options are required for this case?\",\"answer\":\"RADFRAC uses a total condenser and a kettle reboiler, with number of stages taken from DSTWU and distillate rate plus reflux ratio matching the DSTWU-derived values.\"}]","DSTWU and RADFRAC Distillation Models - Tutorial - #2 | DOCX"]