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Transcript of Enhancing Paper Mill Performance through Advanced Diagnostics Services Dr. BS Babji Process...
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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