Transcript Advanced Drystock Control

Advanced Drystock Control (ADC)
to reduce the ‘residual’ basis weight, moisture, and caliper profiles
CIMExcel Software Inc.
Control Systems Engineering company located in Vancouver, Canada.
Provides Simulators, Advanced Control and Optimization Systems for,
• Pulp and Paper Industry
• Energy and Power Industry
• Mineral Processing Industry
• Nuclear Industry
Pulp and Paper:
• Advanced Paper Machine Control (APMC)
• Roll Quality Optimization (RQO) and Trim Optimization
• Pulp Quality Analysis (PQA)
• Advanced Boiler Control (ABC)
• Energy Management System (EMS)
CIMExcel Software Inc.
Slide 1
Space - Time Control of Paper Machine
Basis Weight, Moisture, Caliper and Coat Weight
Advanced Paper Machine Control (APMC) significantly reduces the variability of
basis weight, moisture, caliper and coat weight for all grades and speeds.
APMC improves grade transition performance.
APMC consists of two parts,
• Advanced Drystock Control (ADC) for MD Control
• Modal Profile Control (MPC) for CD Control
Advanced Drystock Control (ADC) consists of two parts,
• ADC - Thickstock
• ADC - Thinstock
CIMExcel Software Inc.
Slide 2
Space - Time Control of Paper Machine
Basis Weight, Moisture, Caliper and Coat Weight
unconditioned
CD Scans
‘flat’ actuators
‘Residual’
CD Reel average
CD
total
improvement
improvement
~ 1.27 %
~ 0.55 %
‘optimized’
actuators
• The ‘noisy / residual’ CD scans are actually aliased MD variability which is within the scanner scanning time.
• Approximately 80-90 % of the variability of headbox consistency and total head is in the 2 - 50 second range,
and 30-60 % of this variability is in the 2 - 5 second range, and is completely aliasing the scanner CD profile.
• Feedforward ADC (thinstock and thickstock) is required in order to reduce the ‘residual’ CD profile.
CIMExcel Software Inc.
Slide 3
MD to CD Aliasing Problem and Variability Analysis
strong correlation of short term (2 – 5 seconds) variability
spatially
filtered
single
8 scan
average
point
scanner
100 boxes
operation
8 scan
average
100 boxes
headbox
consistency
8 scan
average
100 boxes
30 scan
average
headbox
total head
~ 50 second CD scan time
440 boxes
~ 50 seconds
CIMExcel Software Inc.
Slide 4
Variability Analysis
Single Point Dry Weight (gsm)
Time Series Data
(sampled at 1 cps)
Power
Spectrum
Highest Frequency
(0.5 cps, 2 second period)
Lowest Frequency
(0.000116 cps, 832 second period)
Recirculation Flow Control
2 – 3 second period (0.33 – 0.50 cps)
Possible
Wet-End
Sources
Total Head Control
6 – 3 second period (0.17 – 0.33 cps)
Headbox Consistency Control
6 – 15 second period (0.07 – 0.17 cps)
Drystock Feedforward Control
15 – 25 second period (0.04 – 0.07 cps)
Drystock Feedback Control
25 – 250 second period (0.004 – 0.04 cps)
CIMExcel Software Inc.
Slide 5
Variability Analysis
(for variables with 2 - 50 second periods of variation - within the CD scanning time)
MD Variables
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Size Press / Reel Basis Weight
Size Press / Reel Dry Weight
Coater Basis Weight
Rush - Drag
Vertical Slice
Horizontal Slice
Press Section PLI
Couch Pressure
Scanner Beta Signal
Scanner IR Signals
Scanner Basis Weight
Scanner Dry Weight
Scanner Moisture
Scanner Water
Thinstock Variables
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Total Head
Headbox Consistency
Front-Back Differential Pressure
Stream Valve
Stream Flow
Stock Flow
Cleaner Reject Flows
Screen Reject Flow
Fan Pump Speed
CIMExcel Software Inc.
Thickstock Variables
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Basis Weight Valve
Furnish LD Consistency
Furnish LD Dilution Valve
Broke Chest Consistency
Broke Chest Dilution Valve
Blend Chest Consistency
Blend Chest Dilution Valve
Machine Chest Consistency
Machine Chest Dilution Valve
Stuff Box Consistency
Thickstock Consistency
Slide 6
Performance Analysis Toolkit for
Variability Analysis of MD, Thinstock and Thickstock Variables
High Speed NI-DAQ
Power Spectral Analysis
Time Series Analysis
Backlash - Transport
Signal Processing and Filtering
CIMExcel Software Inc.
Slide 7
Advanced Drystock Control
Headbox Consistency
Total Head
Thinstock Flows
Thinstock Consistencies
Thickstock Flows
Thickstock Consistency
CIMExcel Software Inc.
Advanced
Drystock
Control
Feedforward Control:
Main Dilution
Individual Dilution
Main Slice
signal analysis Individual Actuators
multi-actuator
Basis Weight Valve
response
New Devices
coordination
and optimization
Slide 8
Advanced Drystock Control - Thickstock
transport model, backlash compensator, discrete time control, additives and consistency feedforward
• requires high speed data acquisition and signal processing equipment.
• requires some instrumentation - control device, and possible process reconfiguration.
• new thickstock control programming and tuning services.
CIMExcel Software Inc.
Slide 9
Advanced Drystock Control - Thinstock
Headbox Consistency
Total Head
Thinstock Flows
Thinstock Consistencies
Advanced
Drystock
Control
consistency
feedforward
transport
Main Dilution
Individual Dilution
Main Slice
Individual Actuators
New Devices
multi actuator
response
optimization
• Requires an optical thinstock consistency transmitter strategically located on the headbox approach.
• Requires high speed data acquisition and signal processing equipment.
• Thinstock and headbox analysis and control tuning services.
• Identification of process related variability.
• Possible process-related variability reduction solutions.
• Response analysis testing of potential actuators.
• Possible process equipment and control additions.
• Coordination and optimization of multiple actuators.
• Scanner single point operation required for tuning and optimization.
CIMExcel Software Inc.
Slide 10
Scanner Basis Weight β Signal Corrections
• The scanner basis weight β voltage has a noisy and lagged response as shown in the above displays.
• Some scanner β noise filtering be may be applied which increases the scanner basis/dry weight response lag.
• For a scanner CD speed of 20 cm/s,
the lagged response (without filtering) affects 4 cm of the basis/dry weight CD width and needs to be corrected,
the lagged response (with filtering) affects 10 cm of the basis/dry weight CD width and needs to be corrected.
In single point mode, some attenuation will occur for the 2.0 second period basis/dry weight variability.
CIMExcel Software Inc.
Slide 11
Advanced Drystock Control Project Activities
to reduce the ‘residual’ basis weight, moisture, and caliper profiles
1. Overview Analysis and Report - Proposal
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Scanner Signal Analysis and Correction.
Scanner MD-CD Basis Weight , Dry Weight, and Water baseline performance.
Survey of Thinstock, Thickstock Instrumentation, DCS Loops and Control Devices.
Thinstock and Thickstock Variability Analysis.
Thickstock Control Device Analysis.
Thinstock Control Device Analysis.
2. Thickstock - Detailed Analysis, Design, and Report
3. Thickstock - ADC System (PC-> DCS)
4. Thinstock - Detailed Analysis, Design, and Report
5. Thinstock - ADC System (PC -> DCS)
CIMExcel Software Inc.
Slide 12