Integration of Nonlinear CDU Models in Refinery CDU Models in - PowerPoint PPT Presentation

Integration of Nonlinear CDU Models in Refinery CDU Models in Refinery Planning Optimization Abdulrahman Alattas, Advisor Ignacio Grossmann Advisor Ignacio Grossmann Chemical Engineering Department Carnegie Mellon University 1 EWO Meeting – March 2011

I t Introduction d ti  Refinery production planning models  Optimizing refinery operation  Crude selection C d l ti  Maximizing profit; minimizing cost  LP-based, linear process unit equations , p q  Current Project  Collaboration with BP Refining Technology  Develop a refinery planning model with nonlinear process unit equations  integrate scheduling elements g g 2

Refinery Planning Model Refinery Planning Model Development 3

LP Refinery Planning Model LP Refinery Planning Model Example  Example E ample Fixed Swing  Complex refinery yield cut Crude1 (lighter) 142 0 config ration configuration C Crude Feedstock d F d t k Crude2 (heavier) 289 469  Processing 2 crude Other Feedstock Heavy Naphtha 13 9 Fuel Gas 13 17 oils & importing oils & importing LPG 18 20 heavy naphtha Light Naphtha 6 6 Refinery  Swing cut model Premium Gasoline 20 20 Production Reg. Gasoline 80 92  Offers lower net cost Gas Oil 163 170 & different feed Fuel Oil 148 160 quantities quantities Net Cost Net Cost 89663 89663 85714 85714  Shows benefits of 4 better equations

Refinery Planning Model Refinery Planning Model Development  Focus on the front end of the refinery  Focus on the front end of the refinery  Crude distillation unit (CDU) 5

CDU & C CDU & Cascaded Columns d d C l Cascaded Columns Representation Typical Crude Distillation Column of a Crude Distillation Column 6 ( Gadalla et al, 2003 ) ( Gadalla et al, 2003 )

A Aggregate Model t M d l V V top D L top D 1 Top p Section Top L topfeed V topfee V topFeed L topFeed d F F Feed Feed V botFeed L botFeed V botfee L botfee d d Bottom Bottom Section n L bot Steam B V bot B Steam distillation Conventional distillation 7

NLP R fi NLP Refinery Planning Models Pl i M d l Aggregate Model  Mixed-type distillation cascade   Combines conventional and steam distillation Combines conventional and steam distillation  Challenges with full CDU model Feed  4+ cascaded columns  32+ components 32 Bottom Section F Feed Bottom Section 8

FI M d l FI Model - Intro I t Dist4 Dist4  CDU is a series of fractionation Dist3 T C4 units Dist2 T C3 C3 Dist1  Cut point temperature is the Prod4 T C2 Prod3 separation temperature Feed T C1 Prod2 Component Distribution of A Distillation Column Using FI Prod1 6 5 4  Based on Geddes’ B d G dd ’ 3 3 Log (X Dist /X Prod ) i Slope=1.95 2 fractionation index 1 0 method (Geddes 1958) method (Geddes 1958) -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 -1 1 -2 -3 Slope=3.40 -4 9 Log  io

FI M d l FI Model - Equations E ti  Mass balance  Temperature Tc j  TE j  TI j  1 j 2 Tc j  1  Tc j  Component p  Vapor pressure V distribution        1.17639 1  Tr j , i    5.96346 1  Tr j , i 1.5      / Tr j , i 3  1.319 1  Tr j , i        6  0.559607 1  Tr j , i       Pv j , i  Pc i * Exp  Pc * Exp Pv        0.413999 1  Tr j , i    4.78522 1  Tr j , i 1.5       i  / Tr j , i 3  4.98662 1  Tr j , i         0.891239 1  Tr j , i 6     10

FI M d l FI Model - Remarks R k  FI Model is crude independent  FI values are characteristic of the column  FI values are readily calculated and updated from refinery data  Avoids more complex, nonlinear modeling A id l li d li equations  Generates cut point temperature settings for  Generates cut point temperature settings for the CDU  Adds few additional equations to the planning  Adds few additional equations to the planning model 11

FI M d l FI Model – CDU Example CDU E l GO  FI model  FI model Dist4 T C5  FI model example Dist3 T C4 N Dist2  Venezuelan crude T C3 T C T C Dist1 Dist1 HN HN  40 Pseudo-components, 5 cuts 2 LD Feed T C HD 1  4 cases: BR  Maximizing naphtha (N), heavy naphtha (HN), light g p ( ) y p ( ) g distillate (LD), heavy distillate (HD)  Cut-point temperature and product quantities reflect the different business objectives  Stats Product Gas Cut point temperature B.  Equations: 562 Run Naphtha OH Naphtha H Naphtha L Dist. H NaphthaL Dist. H Dist. H Dist. B. Residue Residue Run  Variables: 568 Max Naphtha 6.2 112.9 35.1 68.6 16.5 60.7 Max Naphtha 272.7 417.0 426.4 526.8 595.3  Solver: CONOPT S l CONOPT 272.7 272 7 386.2 386 2 487 8 487.8 526.8 526 8 595.3 595 3 M Max H Naph. H N h M Max H Naph. H N h 6 2 6.2 10 107.4 4 53.0 3 0 56.1 6 1 16 6 16.6 60 60.7 Max L Dist. 6.2 272.7 111.5 386.2 10.7 398.3 95.0 606.0 16.0 631.1 60.5 Max L Dist.  Time: 0.360 sec Max H Dist. 6.2 272.7 111.5 386.2 10.7 398.3 94.0 526.8 16.9 650.5 60.5 Max H Dist. 13

Pl Planning Model Example i M d l E l Typical Refinery Configuration ( Adapted from Aronofsky, 1978 ) Fuel gas butane SR Fuel gas Prem. Gasoline SR Naphtha Cat Ref Reg. Crude1, Gasoline SR Gasoline … Product CDU SR Distillate Blending Distillate Distillate blending blending Cat Crack Crude2, SR GO …. Fuel Oil Gas oil blending SR Residuum Hydrotreatment 14 Treated Residuum

Planning Model Example Planning Model Example Problem Statement  Information Given  Refinery configuration: Process units  Feedstock & Final Product  Feedstock & Final Product Crude1 Louisiana Sweet Lightest Crude2 Texas Sweet Crude3 Louisiana Sour Crude4 Texas Sour Heaviest  Cases: Processing 2,3 & 4 crude oils Case 1 Crude1 Crude2 Case 2 Crude1 Crude2 Crude3 Case 3 Crude1 Crude2 Crude3 Crude4  Objective  Select crude oils and quantities to process  Maximize profit 15  single period time horizon

Planning Model Example Results Pl i M d l E l R lt  Comparison with the fixed yield and swing cut models  Economics E i  FI calculates the maximum profit scenario Model Case1 Case2 Case3 FI 245 249 247 SC 195 195 191 FY 51 62 59 16

Planning Model Example Results Planning Model Example Results (cont.)  Feedstock results: F d t k lt  Different crude purchase option Model Model Model Model Crude1 Crude1 Crude1 Crude1 Crude2 Crude2 Crude2 Crude2 Crude3 Crude3 Crude3 Crude3 Crude4 Crude4 Crude4 Crude4 C Crude Oil Feed Contributions for Case2 d Oil F d C t ib ti f C 2 FY FY 54 54 46 46 100% Case 1 Case 1 SC SC 90 90 10 10 90% 80% FI FI 72 72 28 28 eed 70% FY FY FY FY 10 10 10 10 41 41 41 41 49 49 49 49 Crude Oil Fe 60% Case 2 Case 2 SC SC 80 80 10 10 10 10 50% Crude3 40% FI FI 10 10 30 30 60 60 Crude2 30% Crude1 FY FY 10 10 31 31 49 49 10 10 20% 10% 10% C C Case 3 Case 3 3 3 SC SC SC SC 70 70 70 70 10 10 10 10 10 10 10 10 10 10 10 10 0% FI FI 10 10 19 19 61 61 10 10 FY SC FI Model Type 17

Planning Model Example Planning Model Example Results (cont.)  Products P d t  Increased reg. gasoline  Different fuel oil rates and treated residue Cases Cases Product Product FY FY SC SC FI FI Refinery Products Slate for Case2 Fuel Gas Fuel Gas 12.7 12.7 9.5 9.5 16.3 16.3 100% Premium Gasoline Premium Gasoline 20.0 20.0 20.0 20.0 20.0 20.0 90% 90% Case 1 Case 1 Case 1 Case 1 Regular Gasoline Regular Gasoline Regular Gasoline Regular Gasoline 20 4 20 4 20.4 20.4 23 4 23.4 23 4 23.4 39 0 39.0 39 0 39.0 80% Fuel Oil Fuel Oil 29.5 29.5 48.4 48.4 25.7 25.7 70% HT Residuum HT Residuum 19.0 19.0 Products Fuel Gas Fuel Gas 12.4 12.4 9.5 9.5 15.9 15.9 60% HTR Premium Gasoline Premium Gasoline Premium Gasoline Premium Gasoline 20 0 20.0 20.0 20 0 20 0 20.0 20.0 20 0 20 0 20 0 20.0 20.0 Refinery P 50% 50% FO Case 2 Case 2 Regular Gasoline Regular Gasoline 20.1 20.1 23.4 23.4 39.0 39.0 40% RG Fuel Oil Fuel Oil 32.1 32.1 48.5 48.5 26.2 26.2 PG 30% HT Residuum HT Residuum 17.0 17.0 FG 20% Fuel Gas Fuel Gas Fuel Gas Fuel Gas 12.3 12.3 12.3 12.3 8.4 8.4 8.4 8.4 15.8 15.8 15.8 15.8 10% Premium Gasoline Premium Gasoline 20.0 20.0 20.0 20.0 20.0 20.0 0% Case 3 Case 3 Regular Gasoline Regular Gasoline 19.9 19.9 20.3 20.3 38.7 38.7 FY SC FI Fuel Oil Fuel Oil 32.1 32.1 52.0 52.0 26.6 26.6 18 Model Type HT Residuum HT Residuum 17.4 17.4