Enhancing Paper Mill Performance through Advanced Diagnostics Services
Dr. BS Babji
Process Automation Division
ABB India Ltd, Bangalore
IPPTA Zonal Seminar
on
Best Maintenance Practices in Pulp and Paper Mill to Improve Profitability
17th & 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
Mill performance decreases over a period of time
Pro-Active, not Re-Active
Diagnose
• Measure performance gap
• ROI Estimation
• Prepare action plan
Implement
• Apply corrective actions
• Improve Performance
Sustain
• Manage Performance gap
• Diagnose
• Implement
• Condition monitoring
Measure and Reduce Performance Gap and sustain it through the plant life cycle
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Advanced Performance Diagnostics Platform
Features:
Service
Experts
Automatic data collection and analysis
Multiple Applications
• DCS
• Control Loops
• QCS
• Drives
Archiving of the information
• Benchmarking
• Planning maintenance schedules
Secure
Remote
Connection
Advanced Service
Delivery Platform
Performance Applications
• Equipment
• Process
Local
Users
DCS
QCS
Drives
Remote Connectivity
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Control Loops Performance
Simple PID utilization
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.
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15%
30%
35%
25%
Manual Operation
Output Out of range
Increasing Variability
Improving process
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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
•
•
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Many times default parameters are used
Parameters unchanged after initial commissioning
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Loop Performance Diagnosis example : oscillating loops
cycling load
Valve stiction
F
FC
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.
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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 evaluate
Many 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
loops
Challenge 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
Over Control
Offset
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Error Dead Band
Slow Control
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Control Loops Maintenance: Performance Diagnosis
Control Output Saturation
Valve stiction
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Control Valve Sizing
Control Valve Leakage
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Control Loops Maintenance: Performance Diagnosis
Measurement Out of range
Persistent Disturbances
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Excessive Noise
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
Manual Operation
Original Tuning
(Unstable)
New Tuning
• Investigation of Root Cause Disturbances
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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
QCS
Expert
Remote
DCS
Expert
Drives
Expert
Remote
Service
Secure Access
Local
Track
Continuous
Diagnostics
• Continuous monitoring of key Performance
Indices ( KPIs)
• Send notification automatically to
concerned managers
User Defined Access
Drives
QCS
DCS
Advanced Diagnostics Platform for SCAN and TRACK activities
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Control Loops Maintenance: Benefits
150
0.3% Target Shift in Moisture
0.1 Target Shift in Basis Weight
150
125
Occurrence: Normal
125
100
100
Occurrence
75
50
75
50
25
25
0
0
-0.3
-0.2
-0.1
0
+0.1
+0..2
+0..3
-0.5
0.0
+0.5
+1.0
+1.5
Shifting of the targets for Moisture & Basis Weight results in Fiber and energy savings.
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Control Loops Maintenance: Benefits
3rd Section Steam Closed loop Response
Before
80
75
After
62.5
10 min
SP and PV
SP & PV
3rd Section Steam - Closed Loop Test
70
60.0
57.5
4.2 min
65
72.5
70
Output
Output
70.0
65
67.5
65.0
60
62.5
0
10
20
30
40
50
60
70
80
Data Points, Ts = 15 sec
90
100
110
120
0
250
500
750
1000
Data Points, Ts = 1 sec
1250
1500
1750
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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