INTRODUCTION TO CHEMICAL PROCESS SIMULATORS

Transcription

1 INTRODUCTION TO CHEMICAL PROCESS SIMULATORS DWSIM Chemcal Process Smulator A. Carrero, N. Qurante, J. Javaloyes October 2016

2 Introducton to Chemcal Process Smulators Contents Monday, October 3 rd 2016 Introducton to Sequental Modular Steady State Process Smulators Get used to workng wth DWSIM and COCO Monday, October 10 th 2016 Smulaton of Chemcal Reactors Monday, October 17 th 2016 Smulaton of Dstllaton Columns Monday, October 24th 2016 Case studes 2 A. Carrero, N. Qurante & J. Javaloyes

3 Introducton to Chemcal Process Smulators Flowsheetng Flowsheetng s a systemc descrpton of materal and energy streams n a process plant by means of computer smulaton wth the scope of desgnng a new plant or mprovng the performance of an exstng plant. Flowsheetng can be used as ad to mplement a plantwde control strategy, as well as to manage the plant operaton. Alexander C. Dman (2003) 3 A. Carrero, N. Qurante & J. Javaloyes

4 Introducton to Chemcal Process Smulators Input streams Process Flowsheet Output streams Input streams Process Flowsheet Output streams Operatng Condtons Unt Parameters Operatng Condtons Unt Parameters Smulaton Desgn Objectve Functon Objectve Functon Input streams Process Flowsheet Output streams Input streams Process Flowsheet Output streams Operatng Condtons Optmzaton Unt Parameters Operatng Condtons Synthess Unt Parameters 4 A. Carrero, N. Qurante & J. Javaloyes

5 Introducton to Chemcal Process Smulators Archtecture of Process Smulators Sequental-Modular Based on the concept of modularty, whch extends the chemcal engneerng concept of the unt operaton to a unt calculaton by the computer code responsble for the calculaton of sngle process unt. The computaton of the flowsheet takes place unt by unt followng a calculaton sequence. Equaton-Orented (Smultaneous-Nonmodular) The complete model of the flowsheet s expressed n the form of one large sparse system of nonlnear algebrac equatons that s smultaneously solved for all the unknowns. Smultaneous-Modular Combnaton of Sequental-Modular and Equaton Orented approaches 5 A. Carrero, N. Qurante & J. Javaloyes

6 Introducton to Chemcal Process Smulators Commercal Steady-State Process Smulators Sequental Modular approach Aspen Plus Aspen Hysys ChemCAD PRO II Equaton Orented approach gproms VMGSm Aspen Plus n EO Aspen Custom Modeler UnSm Free Steady-State Process Smulators Sequental Modular approach Equaton Orented approach DWSIM ASCEND COCO 6 A. Carrero, N. Qurante & J. Javaloyes

7 Introducton to Chemcal Process Smulators Sequental Modular Process Smulators Graphcal User Interface Input Output Unt module lbrary Executve Program Themodynamc methods Szng and costng database Numercal routnes Physcal property database Fgure reproduced from Introducton to Software for Chemcal Engneers, M. Martn (2015) 7 A. Carrero, N. Qurante & J. Javaloyes

8 Introducton to Chemcal Process Smulators Sequental Modular Process Smulators Advantages + Easy programmng and mantenance. + Robustness and relablty. Specfc soluton methods are developed for each process unt. + The unt blocks can be easly added to or removed from the flowsheet. Dsadvantages SM s well suted to process smulator, but not to desgn or optmzaton, snce an teratve procedure s requred to satsfy the constrants. Need for topologcal analyss and systematc ntalzaton of tear streams. Present dffcultes wth flowsheets nvolvng a large number of recycle streams. Rgd drecton of computaton, normally outputs from nputs. 8 A. Carrero, N. Qurante & J. Javaloyes

9 Introducton to Chemcal Process Smulators Physcal Property Servce Facltes # Supply estmates for a number of dfferent physcal propertes whle the smulaton s runnng. # Phase equlbrum represent one of the most mportant physcal propertes, as many chemcal processes smulatons nvolve dstllaton, strppng, evaporaton or lqud-lqud separaton. Solvng the mass and energy balances for these operatons necesstates predctng the Vapor Lqud Equlbrum (VLE) Lqud Lqud Equlbrum (LLE) # Estmaton of physcal propertes can consume up to 90% of the computaton tme of a smulaton. Property packages are used to predct the phase equlbrum behavor of pure components and mxture systems 9 A. Carrero, N. Qurante & J. Javaloyes

10 Introducton to Chemcal Process Smulators Phase Equlbrum A closed system that contans more than one phase, at constant Pressure and Temperature, s at equlbrum f: I II F f f f Isofugactes Where f s the fugacty of Component n Phases I, II, F Vapor Lqud Equlbrum f V f L f V s the fugacty of Component n the vapor phase f L s the fugacty of Component n the lqud phase 10 A. Carrero, N. Qurante & J. Javaloyes

11 Introducton to Chemcal Process Smulators Equaton-of-State Method Vapor-phase fugacty V V f y P Lqud-phase fugacty where ln 1 L L f x P y and x are the mole fracton of Comp n the vapor and lqud phases, respectvely V L and are the vapor and lqud phase fugacty coeffcents, respectvely P s the system pressure The fugacty coeffcents for each phase are determned wth the followng expresson P V RT dp j RT 0 n P T, P, n 11 A. Carrero, N. Qurante & J. Javaloyes

12 Introducton to Chemcal Process Smulators Equaton-of-State Method Vapor-phase fugacty V V f y P Lqud-phase fugacty where ln 1 L L f x P y and x are the mole fracton of Comp n the vapor and lqud phases, respectvely V L and are the vapor and lqud phase fugacty coeffcents, respectvely P s the system pressure The fugacty coeffcents for each phase are determned wth the followng expresson P V RT dp j RT 0 n P T, P, n EOS 12 A. Carrero, N. Qurante & J. Javaloyes

13 Introducton to Chemcal Process Smulators Actvty Coeffcent Method Vapor-phase fugacty Lqud-phase fugacty V V f y P L 0 f x f where y and x are the mole fracton of Comp n the vapor and lqud phases, respectvely V s the vapor - phase fugacty coeffcent s the lqud - phase actvty coeffcent 0 f s the fugacty of Comp. at standard state In ths case, thermodynamc models are requred for (from a equaton of state) and (from a lqud-phase actvty coeffcent model) 13 A. Carrero, N. Qurante & J. Javaloyes

14 Introducton to Chemcal Process Smulators Actvty Coeffcent Method At moderate pressures: # The vapor phase can be consdered deal 1 therefore V f y P V # Standard State fugacty f p dp p RT c 0 0 sat P v 0 exp sat p therefore f L 0 p x Poyntng correcton factor 14 A. Carrero, N. Qurante & J. Javaloyes

15 Introducton to Chemcal Process Smulators Vapor Lqud Equlbrum Example (Dechema Chemestry Data Seres) 15 A. Carrero, N. Qurante & J. Javaloyes

16 Introducton to Chemcal Process Smulators Decson tree for the selecton of the thermodynamc property model Equatons of state model Pressure Polarty Actvty coeffcent model No Any polar component? Yes No Any pseudo component? Yes Any Electrolyte? Yes Electrolyte NRTL Ptzer Bromley-Ptzer Peng-Robnson (PR) Soave-Redlch-Kwong (SRK) Lee-Kesler-Plöcker No Under vacuum condtons? Yes No Chao-Seader Grayson-Streed Braun K-10 Ideal Braun K-10 Operatng pressure low to medum 10 bar? Yes PSRK PR or RKS wth MHV2 mxng rules No Bnary teraton coeffcents avalable? No Yes Bnary teraton coeffcents avalable? No Schwartzentruber-Renon PR or RKS wth WS mxng rules PR or RKS wth MHV2 mxng rules Yes Wlson NRTL UNIQUAC No Lqud-lqud equlbrum? Lqud-lqud equlbrum? No UNIFAC Yes Yes NRTL UNIQUAC UNIFAC LLE 16 A. Carrero, N. Qurante & J. Javaloyes

17 Introducton to Chemcal Process Smulators Get used to workng wth Process Smulators FIRST STEPS 1. Compounds 2. Property Packages 3. Flash Algorthm 4. System of Unts 5. Feed nlet data 6. Unts Specfcatons 7. Actvate/recalculate all 8. Revew of the results 17 A. Carrero, N. Qurante & J. Javaloyes

18 Introducton to Chemcal Process Smulators Get used to workng wth Process Smulators DWSIM COCO Deactvate Abort calculaton Actvate Recalculate All Valdate Solve 18 A. Carrero, N. Qurante & J. Javaloyes

19 Introducton to Chemcal Process Smulators Get used to workng wth DWSIM and COCO Flash dstllaton 1 An equmolar mxture of benzene and toluene s subjected to flash dstllaton at a pressure of 1 bar n the separator. Determne the compostons (n mole fracton benzene) of the lqud and vapor leavng the separator when the feed s 25% vaporzed. Estmate the temperature n the separator. Senstvty analyss 0% vaporzed 50% vaporzed 75% vaporzed 100% vaporzed 19 A. Carrero, N. Qurante & J. Javaloyes

20 Introducton to Chemcal Process Smulators Get used to workng wth DWSIM and COCO Flash dstllaton kmol/h fv = 0.25 T? Vapor fracton Temperature (ºC) A. Carrero, N. Qurante & J. Javaloyes

21 Introducton to Chemcal Process Smulators Get used to workng wth DWSIM and COCO Vapor Lqud Equlbrum Dew pont Bubble pont 21 A. Carrero, N. Qurante & J. Javaloyes

22 Introducton to Chemcal Process Smulators Get used to workng wth DWSIM and COCO Flash dstllaton 2 Calculate the composton of the fnal stream n the followng process flowsheet. 25ºC 95 kpa Ethanol kmol/h Acetone kmol/h 65ºC 25ºC X acetone X ethanol Use UNIQUAC thermodynamc package X acetone X ethanol 22 A. Carrero, N. Qurante & J. Javaloyes