Enhancing Paper Mill Performance through Advanced Diagnostics ServicesDr. BS Babji

Process Automation Division

ABB India Ltd, Bangalore

IPPTA Zonal Seminar onBest Maintenance Practices in Pulp and Paper Mill to Improve Profitability17th & 18th July, 2014

Outline

Introduction

Advanced Performance Diagnostics Platform

Control Loop Performance Improvement Services

Summary

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Introduction

Reliable and consistent equipment are needed to•Reduce energy consumption•Minimize downtime•Optimal use of raw material

DCS, QCS and Drives are important assets of a paper mill

Traditional Maintenance methods are inadequate

Need Maintenance strategies that are:•Proactive and Predictive•Quick and timely resolution of issues•Cost effective

Advanced Diagnostics Services are available to address such maintenance needs of Pulp and Paper mills.

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Advanced Diagnostics Services Methodology

Diagnose • Measure performance gap• ROI Estimation• Prepare action plan

Implement• Apply corrective actions• Improve Performance

Sustain • Manage Performance gap

• Diagnose• Implement

• Condition monitoring

Pro-Active, not Re-ActivePro-Active, not Re-Active

Measure and Reduce Performance Gap and sustain it through the plant life cycle

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Mill performance decreases over a period of time

Advanced Service Delivery Platform

QCS DrivesDCS

Service Experts

Performance Applications• Equipment• Process

Local Users

Secure Remote Connection

Advanced Performance Diagnostics Platform

Features:

Automatic data collection and analysis

Multiple Applications•DCS•Control Loops•QCS•Drives

Archiving of the information•Benchmarking•Planning maintenance schedules

Remote Connectivity

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Control Loops Performance

PID Controller• Important assets in a pulp and paper mill• Includes both hardware and software

PID Controllers are designed to: Regulate the process Reduce product quality variations Improve operations

However, it is observed that PID Loops : are not being maintained are standing in the way of production and performance.

Manual OperationOutput Out of rangeIncreasing VariabilityImproving process

35%

15% 30%

25%

Simple PID utilization

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Control Loops Perfromance Deterioration

Change in process characteristics •Process behavior changes with time as compared to original design. •Plants are modified, debottlenecked or added with new equipment •Equipment fouling, varying plant loads, seasonal changes

Operations •Operator do not operate some loops in their design mode of operation due to various reasons

Control valve problems•Hysteresis, stiction, nonlinear characteristics and Valve sizing

PID Tuning parameters•Many times default parameters are used•Parameters unchanged after initial commissioning

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Loop Performance Diagnosis example : oscillating loops

F

FC

cycling load

tight tuning

Oscillation could be due to:•Controller is tuned too aggressively •Control valve is affected by stiction •upstream system oscillation generating a disturbance on the loop.

Valve stiction

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Benefits of Process Variability Reduction

Increased process variability leads to•Quality problems•Increased operating costs

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Control Loops Performance Assessment

Few Control Loops•Easy to evaluateMany Control Loops • Time consuming to collect data and analyze it to

find the problems• Impractical to find with simple tools• Hard to interpret dependencies between control

loopsChallenge to handle• Increasing complexity of automation• With less technical resources

Need a systematic and automated method with suitable tools.

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Control Loops Maintenance: Performance Diagnosis

Diagnose issues related to Control, Process and Signal Conditioning

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Control Loops Maintenance: Performance Diagnosis

Error Dead Band

Offset Slow Control04/19/23 12

Over Control

Control Output Saturation Control Valve Sizing

Valve stiction Control Valve Leakage

Control Loops Maintenance: Performance Diagnosis

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Control Loops Maintenance: Performance Diagnosis

Measurement Out of rangeExcessive Noise

Persistent Disturbances Stepout

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Control Loops Maintenance: Implementation

Examples• Prioritized Control Loops tuning

• Instrumentation calibration or repair• Control Loop Configuration

Enhancements

• Valve and positioner repair

• Base tuning prior to APC Projects

• Investigation of Root Cause Disturbances

Original Tuning(Unstable)

New Tuning

Manual Operation

Original Tuning(Unstable)

New Tuning

Manual Operation

Original Tuning(Unstable)

New Tuning

Manual Operation

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Control Loops Maintenance: Sustain

Scan• Automatic data collection and diagnosis at

scheduled intervals• Implement the corrections• Periodic detailed analysis of the diagnosis

results for process improvements

Track• Continuous monitoring of key

Performance Indices ( KPIs)• Send notification automatically to

concerned managers

Advanced Diagnostics Platform for SCAN and TRACK activities

Drives QCS DCS

User Defined Access

QCS Expert

Drives Expert

DCS Expert

RemoteService

Local

RemoteSecure Access

ContinuousDiagnostics

Control Loops Maintenance: Benefits

0.1 Target Shift in Basis Weight

0

25

50

75

100

125

150

Occ

urre

nce:

Nor

mal

-0.3 -0.2 -0.1 0 +0.1 +0..2 +0..3

0

25

50

75

100

125

150

Occ

urre

nce

-0.5 0.0 +0.5 +1.0 +1.5

0.3% Target Shift in Moisture

Shifting of the targets for Moisture & Basis Weight results in Fiber and energy savings.

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Control Loops Maintenance: Benefits

57.5

60.0

62.5

62.5

65.0

67.5

70.0

72.5

0 250 500 750 1000 1250 1500 1750

3rd Section Steam - Closed Loop Test

SP

and

PV

Out

put

Data Points, Ts = 1 sec

65

70

75

80

60

65

70

0 10 20 30 40 50 60 70 80 90 100 110 120

3rd Section Steam Closed loop Response

SP

& P

VO

utpu

t

Data Points, Ts = 15 sec

Before After

10 min

4.2 min

Reduced response time after tuning results in faster recovery after • sheet breaks• grade changes• start ups.

This results in increased production and reduced broke.

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Summary

• Proactive and predictive maintenance strategies meet the challenges of reliability and consistency of equipment in pulp and paper mills..

• Service methodology of ‘Diagnose, Implement and Sustain ‘ helps in reducing the downtime and improve the performance of assets in a mill.

• Innovative service delivery platforms with sophisticated software tools are available for continuous automatic data collection and analysis to diagnose the problems in DCS, QCS and Drives..

• Control Loops are important assets in a pulp and paper mill and their performance deteriorate over a period of time due to changes in process characteristics, wear and tear, controller tuning, seasonal changes etc

• Control Loop Performance Diagnostics & improvement services help in • Improving product quality, • increasing the thruput• reducing energy consumption

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Thank You

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