© ABB

| Slide 1 May 2, 2016

CONTINUOUS DIGESTER OPTIMIZATION USING ADVANCED PROCESS CONTROL

CSI 2016: April 27-28, 2016

Abhijit Badwe

ABB Pulp & Paper Control Systems Tech. Centre, Singapore

© ABB

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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

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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 15-20 min)

• Assumed blow consistency

• Chip level variation results in varying degrees of cooking

© ABB

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Digester Kappa (end-point) control Conventional approach

Challenges:

Large time delay

Infrequent blow line

Kappa measurement

Non-linear process

interactions

Chip-size, packing

density and raw

material variations

Seasonal variations

Supervisory control

© ABB

| Slide 5 May 2, 2016

Digester chip level control Conventional approach

Challenges

Blow flow as Primary

Manipulated Variable

Estimated blow

consistency

Varied Digester bottom

conditions

Variations in chip

retention time

Supervisory control

© ABB

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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.

© ABB

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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

Model Predictive Control (MPC)

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| Slide 8 May 2, 2016

Digester mid-point Kappa Control Model Predictive 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

Kappa MPC control

© ABB

| Slide 9 May 2, 2016

Digester chip level control Model Predictive 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

MPC for Level control

© ABB

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© ABB Group

May 2, 2016 | Slide 10

OPT800 Cook/C

Continuous Digester Advanced Process Control System

DCS

Continuous Cooking Process

Tracking

Function

Soft Sensor

Constraint

Management

Module

Model

Predictive

Controller

Operator

Displays

OPT800 Cook/C

Process Variables

Tracked Measurements

Soft Sensor Measurements

Operating Parameters

CV Targets

Optimized Setpoints

Dynamic

Constraints Model

Predictions

PVs

PVs

PVs PVs PVs

© ABB

| Slide 11

© ABB Group

May 2, 2016 | Slide 11

OPT800 Cook/C

System Architecture using 800xA APC platform

AC800M

Remote I/O Field

Devices

Engineering Station

Aspect

Servers

Process Portal Client

AC800 Connectivity

Servers

Operator HMI

• MPC faceplates

• MPC tuning

• Process graphics

800xA Run Time Components

• APC Afw service

• APC engines / algorithms

• MPC Control Applications

• Kappa

• Level

AC800M Run Time Components

• PPOptCook/C CoreLib

• PPOptCook/C TemplateLib

• Control connections to sensors and PID’s

800xA Model Builder (off-line)

• Off-line Engineering tool kit, for

Model Identification, Controller

Tuning, and Simulation

IMP Run time Engine

• Kappa Inferential measurement

800xA APC Interface Lib

© ABB

| Slide 12 May 2, 2016

Case study : Mondi Swiecie, Poland Digester Advanced Process Controls

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

APC improves digester operations in Mondi

© ABB

| Slide 13 May 2, 2016

Case study : Mondi Swiecie, Poland APC Methodology

• Control Loop Audit

• Analysis, Findings

• Action plan

Process Fingerprint

• Chip Bin

• Impregnation Vessel

• Digester Vessel

Pulp Tracking • Blow consistency

• Kappa model

• Install IMP

• Data collection

Soft Sensor Models

• Kappa MPC

• Dig level MPC

• Step Test

• Develop models

• Deploy MPC

MPC • Performance Test

• Case Study

• Success Story

Results Report

• Quarterly Audit

• Benchmarking results

• ServicePort

Performance Monitoring

Step 1:

Diagnose Step 3:

Sustain Step 2:

Implement

Service Service

Diagnose Implement Sustain

© ABB

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Case study : Mondi Swiecie, Poland Digester APC Overview

Operator overview

APC display

Faceplates

Switch APC and

Supervisory mode

© ABB

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Case study : Mondi Swiecie, Poland Mid-point Kappa control Results before & after APC implementation

Performance test run results Kappa variability reduced by 56.4%

Average Upper Lt Lower Lt Sigma % results

Before APC 88.86 89.00 85.00 3.68 36.8%

After APC 87.93 89.00 85.00 1.61 71.4%

Improvements 0.93 2.08 94%

Before APC % of data within Limits 36.8%

After APC % of Data within Limits 71.4%

Blow Kappa Test Run

56.4%

© ABB

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Case study : Mondi Swiecie, Poland Residual Alkali control Results before & after APC implementation

C12 Residual Alkali Variability reduced by 48%

0 .0 0

0 .2 5

0 .5 0

0 .7 5

1 .0 0

1 .2 5

T w o S ig m a C o m p a r i so nP o i n t s = 4 5 6 1

2

Sig

ma

1 2

C 1 2 R e A lk a l i_ B e fo r e A P C C 1 2 R e A lk a l i_ A fte r A P C

C 1 2 R e A lk a l i_ B e fo r e A P C 1 .3 2 7 7 0 4 2C 1 2 R e A lk a l i_ A fte r A P C 0 .6 4 7 9 4 3 3

5

6

7

8

9

1 0

1 1

1 2

1 3

1 4

0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 2 5 0 0 3 0 0 0 3 5 0 0 4 0 0 0 4 5 0 0

O v e r la y C o lu m n C o m p a r is o nC o lu m n s = 2 , P o in ts = 4 5 6 1

Re

s

Alk

ali

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

48 %

© ABB

| Slide 17 May 2, 2016

Case study : Mondi Swiecie, Poland Digester chip-level control Results before & after APC implementation

Trend captured from customer historian while

commissioning OPT800 Cook/C for digester

Dig chip level - 5 days trend 40% reduction in 2-Sigma

APC ON APC OFF

0

5

1 0

1 5

2 0

2 5

T w o S i g m a C o m p a r i s o nPo i n t s = 4 5 6 1

Dig

C

hip

L

ev

el

1 2

D ig lv l_ B e fo r e A P C D ig L v l_ A fte r A P C

D ig lv l_ B e fo r e A P C 2 6 .6 7 2 5 8 8 3D ig L v l_ A fte r A P C 1 6 .1 3 2 9 8 2 3

40%

© ABB

| Slide 18 May 2, 2016

Case study : Mondi Swiecie, Poland Results: Digester chip-level control

• Stable blow flow

• Lower variations in

production rate MV

(measured)

• Improved cooking

conditions

• Stabilized downstream

washing process

Results Stabilized digester operations - blow flow

© ABB

| Slide 19 May 2, 2016

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.”

© ABB

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Happy Customer

Month DD, Year

|

Sli

de

20

© ABB

Group

© ABB

| Slide 21 May 2, 2016

Contact information

If you have further questions, please contact me at:

Presenter : Abhijit Badwe

Company : ABB Pte Ltd

Contact phone : (+65) 9665-9947

Contact e-mail : abhijit.badwe@sg.abb.com

© ABB

| Slide 22