CONTINUOUS DIGESTER OPTIMIZATION USING ADVANCED PROCESS CONTROL

Transcription

1 CSI 2016: April 27-28, 2016 CONTINUOUS DIGESTER OPTIMIZATION USING ADVANCED PROCESS CONTROL Abhijit Badwe ABB Pulp & Paper Control Systems Tech. Centre, Singapore Slide 1

2 Continuous Digester Advanced Control Outline Challenges in continuous cooking Conventional approaches to control Need for multivariable control Advanced control for continuous digesters: OPT800 Cook/C Case Study: Implementation of OPT800 Cook/C Slide 2

3 Pulp Mill Operation Challenges in Continuous Cooking Variations in raw material Production rate changes Large transport delays Complex nonlinear dynamics at low Kappa numbers Infrequent Kappa measurements (every min) Assumed blow consistency Chip level variation results in varying degrees of cooking Slide 3

4 Digester Kappa (end-point) control Conventional approach Supervisory control Challenges: Large time delay Infrequent blow line Kappa measurement Non-linear process interactions Chip-size, packing density and raw material variations Seasonal variations Slide 4

5 Digester chip level control Conventional approach Supervisory control Challenges Blow flow as Primary Manipulated Variable Estimated blow consistency Varied Digester bottom conditions Variations in chip retention time Slide 5

6 Continuous Digester Control Need for a multivariable control approach Kappa number affected by H Factor and Alkali/Wood ratio Chip level affected by multivariable effects from: Chip meter speed Blow flow Bottom dilution flow Scraper speed Conventional approaches are usually univariate. Slide 6

7 Model Predictive Control (MPC) Systematic method for solving multivariable problems Main ingredients Process model Constraints Objective function Model predicts system behaviour some steps into the future Solves optimization problem at every sampling time Slide 7

8 Digester mid-point Kappa Control Model Predictive Control Kappa MPC control ANN model for mid-point Kappa (soft sensor) Pulp tracking module: tracks key process variables throughout digester Blow line Kappa used for output bias correction REA (residual alkali) control to the target Slide 8

9 Digester chip level control Model Predictive Control MPC for Level control Model Predicative Control Actively manipulate scrapper speed Blow consistency (soft sensor) Ensure stable fiber discharge (blow flow variations minimized) Stabilize chip column movement to provide uniform cooking conditions CMM constraint Management Module Slide 9

10 OPT800 Cook/C Continuous Digester Advanced Process Control System OPT800 Cook/C Soft Sensor Tracking Function Constraint Management Module Model Predictions Model Predictive Controller Dynamic Constraints Operating Parameters CV Targets Operator Displays PVs PVs PVs PVs DCS Optimized Setpoints PVs Process Variables Tracked Measurements Soft Sensor Measurements Continuous Cooking Process Group Slide 10 Slide 10

11 OPT800 Cook/C System Architecture using 800xA APC platform Operator HMI MPC faceplates MPC tuning Process graphics Process Portal Client Engineering Station 800xA Model Builder (off-line) Off-line Engineering tool kit, for Model Identification, Controller Tuning, and Simulation AC800 Connectivity Servers Aspect Servers IMP Run time Engine Kappa Inferential measurement AC800M Run Time Components PPOptCook/C CoreLib PPOptCook/C TemplateLib Control connections to sensors and PID s AC800M 800xA Run Time Components APC Afw service APC engines / algorithms MPC Control Applications Kappa Level 800xA APC Interface Lib Remote I/O Field Devices Group Slide 11 Slide 11

12 Case study : Mondi Swiecie, Poland Digester Advanced Process Controls APC improves digester operations in Mondi Located in Northern Poland Pulpmill with 2 Fiber lines, 4 Paper Machines Project scope Replace measurex DCS system OPT800 Cook/C for both lines Kappa MPC control Level MPC control OPT800 Wash for both lines Conductivity controls at each stage Dilution Factor control Slide 12

13 Case study : Mondi Swiecie, Poland APC Methodology Diagnose Implement Sustain Step 1: Diagnose Step 2: Implement Step 3: Sustain Service Service Control Loop Audit Analysis, Findings Action plan Process Fingerprint Pulp Tracking Chip Bin Impregnation Vessel Digester Vessel Blow consistency Kappa model Install IMP Data collection Soft Sensor Models MPC Kappa MPC Dig level MPC Step Test Develop models Deploy MPC Performance Test Case Study Success Story Results Report Performance Monitoring Quarterly Audit Benchmarking results ServicePort Slide 13

14 Case study : Mondi Swiecie, Poland Digester APC Overview Operator overview APC display Faceplates Switch APC and Supervisory mode Slide 14

15 Case study : Mondi Swiecie, Poland Mid-point Kappa control Results before & after APC implementation Performance test run results Kappa variability reduced by 56.4% Blow Kappa Test Run Average Upper Lt Lower Lt Sigma % results Before APC % After APC % Improvements % Before APC % of data within Limits 36.8% After APC % of Data within Limits 71.4% 56.4% Slide 15

16 R e s A l k a l i 2 S i g m a Case study : Mondi Swiecie, Poland Residual Alkali control Results before & after APC implementation C12 Residual Alkali Variability reduced by 48% O v e r la y C o lu m n C o m p a r is o n C o lu m n s = 2, P o in ts = T w o S ig m a C o m p a r iso n P o i n t s = C 1 2 R e A lk a li_ B e fo r e A P C C 1 2 R e A lk a li_ A fte r A P C C 1 2 R e A lk a li_ B e fo r e A P C C 1 2 R e A lk a li_ A fte r A P C % D a ta P o in ts C 1 2 R e A lk a li_ B e fo r e A P C C 1 2 R e A lk a li_ A fte r A P C Slide 16

17 D i g C h i p L e v e l Case study : Mondi Swiecie, Poland Digester chip-level control Results before & after APC implementation Dig chip level - 5 days trend 40% reduction in 2-Sigma Trend captured from customer historian while commissioning OPT800 Cook/C for digester T w o S i g m a C o m p a ri s o n Po i n t s = D ig lv l_ B e fo r e A P C D ig L v l_ A fte r A P C APC OFF APC ON % D iglv l_ B eforea P C D ig L v l_ A fte r A P C Slide 17

18 Case study : Mondi Swiecie, Poland Results: Digester chip-level control Results Stabilized digester operations - blow flow Stable blow flow Lower variations in production rate MV (measured) Improved cooking conditions Stabilized downstream washing process Slide 18

19 Customer Testimonials Mr. Tomas Katewicz (Member of Management Board & Production Director) through their (ABB) APC, new and effective solutions have been implemented which are stabilizing strongly the processes of the cooking and pulp washing lines. Mr. Wojciech Jazdziewski (Pulp Mill Assistant Manager) We do believe that the implemented MPC system will allow us to increase production output in a stable way, whereas the high quality parameters of pulp will remain unchanged. I would like to express our appreciation to ABB for implementation and successful start-up of APC for two production lines at Mondi Świecie S.A. Senior Operator (more than 20 years at Mondi) I have never seen in my life the chip level stabilize so beautifully. Slide 19

20 Happy Customer Group Month DD, Year Slide 20

21 Contact information If you have further questions, please contact me at: Presenter : Abhijit Badwe Company : ABB Pte Ltd Contact phone : (+65) Contact abhijit.badwe@sg.abb.com Slide 21

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