Refinery Crude Unit Advanced Control What? Why? How?

Transcription

1 Refinery Crude Unit Advanced Control What? Why? How? Lou Heavner Advanced Applied Technologies Group Process Systems and Solution Division

2 Topics Why Do Crude / Vacuum Units Need Advanced Controls? What Advanced Controls Do We Implement? What s New And Different With Emerson APC Tools? Case Study Slide 2

3 Crude Distillation TI Reflux Drum PC TI T Naphtha Stabilizer Pumparounds Naphtha LGO HGO TI * Crude Oil from Heaters H-2101A/B TI TI TI T I T Overflash T I FI TI TI TI TI TI T-2105 T-2104 T-2103 T-2102 M V T-2107 M V M V M V M V AI D86 95% Flash Pt. Density AI Cloud Pt. D86 5% AI Cloud Pt. AI Color A I LN HN MK LG HG HHG Slide 3 LP Steam Injection TI Atmospheric Residue To Vacuum Column T-2201

4 Crude Unit Product Variability Diesel 90% /10/00 7/9/00 7/9/00 7/8/00 7/8/00 7/7/00 7/7/00 7/6/00 7/6/00 7/5/00 7/5/00 Date Slide 4

5 Crude Unit Characteristics Conditions Are Often Changing Changing Crude Feed Compositions Changing Targets For Sidestream Qualities Product Qualities Measured by Laboratory Samples or Online Analyzers with a lot of delay One Of The Largest Consumers Of Energy In The Refinery One of the most INTERACTIVE units in the refinery difficult to control Primary Yields Set Overall Refinery Yields Slide 5

6 Typical Benefits Unit PredictPro Benefit USc/ bbl Feed Atmospheric Crude Units 5 Vacuum Distillation Units 5 CU Main Fractionator 4 Coker Main Fractionator 8 Slide 6

7 APC Improves Quality Removes process variability Provides real-time predictions of unmeasured qualities Compensates for dead-time and analyzer delays Frequency Naphtha % 100 Point Hot-end Temperature PV Before Deg C Frequency After Hot-end Temperature PV Typically 40-80% reduction in quality variation Deg C Slide 7

8 APC Increases Throughput Ideal for managing multiple constraints Predicts limit violations before they occur Push equipment and plant limits every minute of every day Typically 3-10% increase in throughput. Throughput APC Past Constraints Time Future Production Increase $$ Throughput at limit Operator Setpoint Slide 8

9 APC Reduce Operations & Maintenance Costs Automation of routine tasks increases the loop count per operator Safe Park applications lowers risks during process upsets More stable operation reduces wear-and-tear on machinery Typically 0-4% reduction in O&M costs. Slide 9

10 APC Reduce Incidents Prediction and control against actual equipment limits Automated action on instrument or equipment failure More stable operation reduces opportunity for excursions Typically 10-20% reduction in safety or environmental incident risk. Slide 10

11 APC Minimize Energy Costs Designed to minimize energy when possible Maximize equipment efficiency and heat recovery Optimize tradeoffs in the site utility and fuel balance Typically 2-6% reduction in energy costs. Slide 11

12 APC Reduces Off-spec and Rework Real-time prediction and control of key product qualities Stable operation yields consistent, predictable qualities On-spec blends every time leads to lower inventories and component costs Typically 5-10% reduction in product inventories. Slide 12

13 Hierarchy of Performance Control Enterprise Control Advanced Control Process Control DCS Loop Performance Slide 13

14 Improving Control Performance

15 Reducing Input Disturbances Fuel Gas Heat Combustion Methane Ethane Propane Butane Hydrogen Kcal/mole Kcal/gm Conclusion: Measure and control by mass not by volume! Slide 15

16 Reducing Variability Remove Disturbances - Heater Controls O2 Fuel Gas with Mass Control and Density Feedforward PI Slide 16

17 Heater Excess Air Control Slide 17

18 Main Crude Unit Main feed valve deadband was 5-7%. This caused pressure fluctuations to the desalter units in the preheat train. A lower pressure setpoint was necessary to avoid lifting relief valves. The main feed valve was replaced with a 12 V300 control valve assembly and tuned using Lambda Tuning methodology (avoid interaction with the desalter pressure controller). Pressure fluctuations were reduced to a +/- 1 psi allowing a higher pressure setpoint. Throughput increases have averaged 2000 BPD with a desalter pressure controller setpoint increase. This optimization is presently valued at $1,900,000 annually. Slide 18

19 DeltaV Advanced Control - PredictPro

20 Yesterday s s Technology required you to have a really big one! Slide 20

21 DeltaV: Removing Obstacles To APC Implementation & Maintenance DeltaV APC Projects are 25-50% Faster and Less Costly than traditional APC Projects Team of consultants Slide 21

22 Embedded APC Tools What s s new? NO extra databases NO database synchronization issues NO watchdog timers NO fail/shed logic design NO custom DCS programming NO interface programming NO operator interface development Slide 22 Traditional Advanced Control Embedded APC: Can run in DCS controllers Redundant and fast (1/sec) Integrated operator user interface Configured in DeltaV environment Automated step testing and Model ID

23 Typical APC Project Timeline Months Functional Design Det. Design, Config & Staging Traditional APC Technology Step Tests & Model ID Commissioning Functional Design Det. Design & Config Step Tests & Model ID Commissioning Performed on-site Embedded APC Technology Slide 23

24 DeltaV PredictPRO Slide 24

25 Classical Feedback Control Setpoint + - Error PID Algorithm to make Error zero Move single manipulated variable Plant Current measured value for single controlled variable Slide 25 Control Moves Based on Current Measurement

26 Multivariable Predictive Constraint Control Controlled Variable Modeled Relationship Manipulated Variable Uses Information from The Past To Predict The Future Past Present Future Time Slide 26

27 Multi-Variable Control Problem - Controller + Reflux Temperature Temperature + Controller Reboil Distillation Process - Slide 27

28 Multi-Variable Control Problem + - Controller Reflux Temperature Temperature Controller - + Reboil Slide 28

29 Multivariable Predictive Constraint Control Multiple manipulated variable moves based on predicted plant behaviour Plant Measured Disturbances Multiple measurements of controlled variables Multiple Constraints Multivariable Predictive Constraint Controller Multiple Setpoints Slide 29 Benefits: Reduction in Standard Deviation of 30 to 70%

30 Historically, Advanced Control Was Done in Supervisory Computers Advanced Process Control APC Not redundant Not real-time (1 minute) LAN Proprietary Bus DCS Controller PID Slide 30

31 DeltaV Predict in the Controller Advanced Process Control APC Not redundant Real-time (1 minute) LAN LAN Slide 31 Proprietary Bus DCS Controller PID PID Fieldbus APC Open Bus Redundant and Fault Tolerant Real-time (1 second) Communicates data throughout enterprise

32 MPC Implementation Sequence 1. PreTest and Variable Selection 2. Configure 3. Process Testing 4. Model Building and Validation 5. Controller Simulation 6. Build Operator Interface 7. Controller Download 8. Controller Operation Slide 32

33 Step 2 - Graphical Configuration - MPCPro Function Block Slide 33

34 Configure the MPCPro by Selecting Properties Slide 34

35 Attributes for Control, Manipulated, Disturbance and Constraint Parameters Slide 35

36 Step 3 - Automated Step Testing Step Size Tss Process Steps Manipulated inputs selected for test are changed in a pseudorandom fashion during the test based on the step size and initial starting manipulated input value. Slide 36

37 Step 4 Model Validation - Process Model Displays Produced Slide 37

38 Model Validation Slide 38

39 Step 5 - Controller Simulation Slide 39

40 Step 6 : Automatic Operator Display Trend Window Past Future CVs MVs LVs DVs Slide 40

41 Built-in in LP Optimization 50 psi 120 deg F 100% position 0% position Maximized Minimized Throughput Energy Profit 100 psi 100% position 80 deg F 0% position Slide 41

42 DeltaV Neural Create real-time virtual sensors for periodic lab measurements Easy to understand and use Easy to update and maintain Slide 42

43 Property Estimation When critical measurements are slow to reflect process changes or only lab analysis is available, then parameter estimation can often be used to improve the performance of control and monitoring applications. Measured process inputs their relationship to the property of some process output is used to infer an estimate of the output. Slide 43

44 Example: Crude Column Product Quality FI Crude Column TC TI TI TI TI PC TI TI TI EP EP PP PP Virtual Sensor Virtual Sensor Virtual Sensor Virtual Sensor Predict product qualities from temperature / pressure profile Distillation properties (IBP, 90, EP) Pour, cloud, SUS Updated from lab measurements Real-time estimate used for control FI TI Slide 44

45 Distillation Control Module Standard Distillation Calcs Predict Pro Block Module Library Preconfigured Neural Blocks Slide 45

46 SmartProcess Implementation Months Functional Design Det. Design, Config & Staging Traditional APC Technology Step Tests & Model ID Functional Design Commissioning Det. Design & Config Step Tests & Model ID Commissioning Embedded APC Technology FDS & Confg Step Tests & Model ID Commissioning SmartProcess Applications Slide 46

47 Implementing Advanced Control

48 Refinery APC Example Ergon, West Virginia Slide 48

49 Ergon Project Scope Atmospheric Crude and Vacuum Units 2 Model Predictive Controllers 4 x 4, 3 x 3 3 Neural Networks SR Naphtha 95% point AGO 95% point Wax distillate 95% point Slide 49

50 Atmospheric Column 4 Controlled Variables TC PCT TI PCT Kero Naphtha TI PCT Hvy Kero MPC Crude TC TI PCT AGO Fuel Gas Resid to VAC Column Slide 50

51 Atmospheric Column 4 Manipulated Variables TC Naphtha Kero Hvy Kero MPC Crude TC AGO Fuel Gas Resid to VAC Column Slide 51

52 Atmospheric Column 3 Disturbance Variables TC TI TI Kero Naphtha TI Hvy Kero MPC Crude TC TI AGO Fuel Gas Resid to VAC Column Slide 52

53 Atmospheric Column Neural Network Predictions Column Temps & Yields Column Temps & Yields Predicted NA End Point TC Kero Naphtha Predicted AGO End Point Hvy Kero Crude TC AGO Fuel Gas Resid to VAC Column Slide 53

54 Vacuum Column Controlled Variables PC LC TC PCT VGO VAC P/A TI PCT Wax Dist MPC TI PCT Atm Btms TC Hvy Wax Dist Fuel Gas VAC Resid Slide 54

55 Vacuum Column Manipulated Variables PC LC TC VGO VAC P/A Wax Dist MPC Atm Btms TC Hvy Wax Dist Fuel Gas VAC Resid Slide 55

56 Vacuum Column Disturbance Variables PC LC TI VGO VAC P/A Wax Dist MPC Atm Btms TC Hvy Wax Dist Fuel Gas VAC Resid Slide 56

57 Vacuum Column Neural Network Prediction PC TC LC VGO Column Temps & Yields VAC P/A TI Wax Dist Predicted Wax Distillate 95% Point Atm Btms TC TI Hvy Wax Dist Fuel Gas VAC Resid Slide 57

58 Atm Controller Performance Controller ON Crude Change Naphtha Hvy Kero CV SP MV Lab Spec Kero AGO Slide 58

59 Neural Results Naphtha 95% Point SR Naphtha EP Crude Switch Lab NN Prediction Filtered 07-Aug-03 00:00:00 09-Aug-03 00:00:00 11-Aug-03 00:00:00 13-Aug-03 00:00:00 Slide 59

60 Variability Reduction Before After Average St. Dev. Average St. Dev. Reduction in Std. Dev. Atm Column SR NAPHTHA EP % AGO EP % OVERHEAD TEMP % KERO DRAW TEMP % HVY KERO TEMP % AGO DRAW TEMP % Vacuum Column WAX DIST 95% POINT % VGO CHIMNEY TEMP % WAX VAP TEMP % H WAX VAP TEMP % Slide 60

61 Crude/Vac Unit APC Project Timeline Activity Functional Design Specification DeltaV APC Projects are 25-50% Faster and Less Costly than traditional APC Projects Application Configuration Step Tests Commissioning Timeframe 3 weeks < 1 day 10 days 1 week Scope: Two 4x4 MPC controllers, 3 Neural Nets Slide 61

62 Standard Operator Display Slide 62

63 Summary APC has a large value for Crude Units DeltaV Embedded APC dramatically lowers implementation costs Less need for expensive consultants Quicker implementation Easier to maintain Can be used with other DCS platforms Simple Optimization can be done in APC layer Slide 63

64 Learning More About DeltaV Advanced Control Book was inspired by DeltaV Advanced Control Products. This book was introduced at ISA2002 may also be ordered through ISA, Amazon.com or at EasyDeltaV.com/Bookstore The application sections include guided tours based on DeltaV Advanced Control Products CD provides an overview video for each section and examples. Copies of the displays, modules, and HYSYS Cases are included on the CD. Slide 64

65 Questions? Comments? Questions? contact (512) Slide 65

66 Thank You! Questions? Slide 66