Process Analytics: Improving Measurement Capability in your Plant AIChE Meeting: Nov. 17, 2009 Steve...
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Transcript of Process Analytics: Improving Measurement Capability in your Plant AIChE Meeting: Nov. 17, 2009 Steve...
Process Analytics: Improving Measurement Capability in your Plant
AIChE Meeting: Nov. 17, 2009
Steve WrightProcess & Environmental Analytics
Eastman Chemical Company
Overview of Presentation
Introduction Sampling Theory – Why Analyzers? Process Analyzers and Sensors Sampling Systems Ownership and Maintenance Summary and Q&A
Introduction
Process Analytics is the
• Analytical Measurement of Chemical Composition Chemical Properties
of a Chemical Production Stream
• Using one, or more, of four approaches In-Situ / In-Line Extractive At-Line Ambient Detection
100ppm
100ppm
Eastman Process Analytics: Kingsport
Almost 2000 Process Analyzers and Chemical Sensors Personnel: 41 chemists, engineers, techs and analysts. Support: 24x7 where needed. Responsibilities include:
• Analyzer consultation/ specification
• Analyzer system design/purchase
• Sample system construction
• Installation/checkout
• Preventative maintenance
• Reactive maintenance
• Analyzer succession planning
Why Analyzers?
Measurement & Control
MEASUREMENT
CONTROL
Can’t do one without the other..
Majority of Process Measurement Tasks Can be Done Using Simple Sensors or Lab Analyses
Pressure, Temperature, Flow, Mass Lab measurements – slow and steady processes..
For the exceptions – process analytics..
Traditional Reactor Sampling Path
Insert Break
LabQueue
EnterSampleOrder
Ye Olde Bucket/SpigotWait for Truck
Wait for Truck II
GC Results
Sample Point
Create Report
Results!
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GARBAGE ZONE
Under-Sampling (Aliasing)
Comfort Zone – >4F to “over-sampling”
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Meeting Nyquist.. Just barely
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GARBAGE ZONE
Sampling Okay – but it’s breaking the bank..
LAB $$$$$$$$$$$$$$$$$$$
Transitioning from Product A to Product B
How long can we continue making “Good A”And when can we call “Good B”?
Good Measurement canLead to Great Processes
100%
0%
?Good A Good B
??
Time
Target Time
Late
EarlyEarly Error Lead
Late ErrorLag
Time
Pro
cess
Var
iabl
e
“While we’re here, let’s savetime & take the next sample”
“Just trying to keep up”
Input Lead/Lag Control Complexities….
Variability Complicates it even More…
Crew 1 is timely..Crew 2 isn’t..
Processtrend
Sample Time-Stamping Errors
Early Late
Good Measurement canLead to Great Processes
A B at 70 deg C 0-100% in 20 minutesA B at 20 deg C 0-100% in 640 minutes
While waiting 2 hours for analysis 20% change!!!
TwoHours
70 deg C20 deg C
% Completion
60% 80%
The Reaction Continues…
Models
Ultimate process understanding “victory” Control process with lean measurements, T, P, flow, etc. “As good as their input data” Model response surface must be well-defined Models tend to perform best in “known territory”
• Prediction weakness can occur during critical times: Upsets Start-Ups/Shut-Downs Product transitions
Direct measurement benefits• Often easier to set up and maintain than complex models
• Full process interaction / understanding is not required to measure
• Output can help build better models!
“The Wall” “The Wall”
Loose measurement& control – broad processperformance
Tight measurement& control
“Wall” = > Impurities, lower value product, permits, safety issues, etc.
Run Closer…
Value Proposition
Process Analyzers & Sensors
Fixed or Dedicated Systems Transmitter Style
oSimple to installo Low costoCan be used as “cheap” analyzers
- If high accuracy not required- Inferential
oExtractive sampling of processes
- Addition of flow cells and sample systemoDirect Insertion
Alan Hensley, 2009
Ambient / Area Point Monitoring
Personnel Protection Leaks or Spills
ElectrochemicaloToxic Gases
• Hydrogen sulfide
• Chlorine dioxide
• Carbon monoxideoOxygen
• % levels
• Oxygen deficiency
• High oxygen in processes
Alan Hensley, 2009
Area / Point Monitoring Combustible Gases
oNormally report values in terms of % of lower explosive limit (LEL)
oNot specific to gas – detect hydrocarbonsoCatalytic sensor
• Combust the sample
• Require oxygeno Infrared sensor
• Can be used in oxygen deficient or inert environments
• Where “poisoning” of catalytic sensor is of concern
Alan Hensley, 2009
Liquid Analytical pH & Conductivity
oSumps / Pure Water / Condensate & Discharges
• Material release
• Quality
• ContaminationoProcess
• Inferential composition measurement
• pH control for reactions / batch processes Dissolved Oxygen
oWastewater Treatment
Oxygen
Fuel Cell % and ppm level measurements
Paramagnetico% level measurementsoOxygen level in nitrogen convey systems
Zirconium OxideoStack monitoringoHandle dirty environmentsoHigh temperature operation
Alan Hensley, 2009
Physical Property Density (not just for mass flow)
o Inferential Composition MeasurementoDepends on process stream
TurbidityoContamination
ViscosityoProcess Control
Alan Hensley, 2009
Fixed or Dedicated Systems
Traditional StyleoAnalyzer is remote from areaoExtractive sampling with sample systemoHigher costoHigher complexityoRequire more care and feedingoStream ComplexityoAccuracyoSpecific
Photometric MethodsPhotometers UV/NIR/Non-dispersive IR Use specific wavelengths = 1 or 2 components Solids: non-contact
o% moisture Gases
oCO, CO2, NOx, SO2 Liquids
o% water, % organic acids
Alan Hensley, 2009
1100 1300 1500 1700 1900 2100 2300
0
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0.4
0.6
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1
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Nanometers
Process Analyzer Availability
If it can be done in the lab, it can installed on-line.• Up-Front cost issues / ROI
• Sample handling issues
Our group will build it if we cannot buy it.• Integration tasks, sample handling systems
• Panel Shop in B-359A
FRONT VIEW
Sampling Systems
Maintenance
Goals
Representative Sampling / Minimal Handling• Want sample to mirror process content
• Minimal interaction with sample
• Minimal sampling delays
Sample Compatibility with Analyzer Specifications• Temperature
• Pressure
• Flow
• Viscosity
• Particulates / Bubbles
• Materials Compatibility
In-situ Measurement
No sampling system• Pipeline/tank/line insertion
• No delay – real time results
Probe design Probe can be removed for cleaning – usually.
• Exceptions would be high pressure / temperature applications
Representative! Passive? Yes.
Extractive Sampling Systems
0-10gpm 0-0.5
gpm
RapidBypassLoop
Filter
DP
Flow Integrity Monitor
Analyzer
SampleLoop
Extractive Sampling Systems
Sample stream removed from main process line Advantages
• Allows isolation from process (cleaning/calibration)
• Filtration, dilution, P/T manipulation
• Improved safety – block/bleed
Difficulties• Must have dP across sample loop - or
• Sample pumping
• Delays
• Returning altered material to process or waste
• Filtration maintenance – when needed
Process Analyzer Maintenance
Ownership Cycle..
Development
Purchase
Installation
Start-UpMaintenance
Improvement
Replacement
70-90%Cost of Ownership
Maintenance is major cost of analyzer installation – process GC example
Reliability Maintenance Approach
Reliability – in degrees..• Ideal
Lasts forever, accurate and precise – cheap to own too.
• Reality (March to Entropy) Machine components wear out Unusual, unexpected events happen
• Goal Want capable function whenever machine is needed
• High Availability Uptime.
Want ownership at lowest possible cost. Reliability-Centered Maintenance Approach
Maintenance Categories
Reactive (RTF)• Appropriate for ultra-high reliability, low criticality systems
• Cheapest / Most Expensive approach – feeling lucky?
Preventative (PrM)• Process analytics use PrM
• Shewhart control charts (+/- 3 sigma, run of eight)
• Scheduled benchmarking visits
Predictive (PdM)• Maximum system availability at minimum cost.
• Relies on obtaining detailed history at component levels.
• We now have tools in-place to transition to PdM where needed.
pH 4pH 4
pH X.XXpH 3.95pH 4.15
Analyzer Benchmarking
Apply standard of known concentration to analyzer
Read analyzer response Compare response to standard response
Within control limits:• Note response, add to control chart
• Walk away, just walk away…..
Outside of control limits, or eight either side of average:
• Note response, add to control chart
• Calibrate analyzer / determine cause / log
Avoids human tendency to over-control, chasing system noise. Much better for process stability.
pH 4.0
pH 3.9
pH 4.1 +3s
-3s
Target
pH 4.00
pH 4 StandardBuffer Solution
Process Analyzer Maintenance
Effective PrM has greatly improved reliability of our analyzers• High availability up-times
• Analyzer data can be trusted for monitoring & control
Productivity (analyzers/analyst) has greatly improved over the last 20 years• Better analyzer technology
• Better diagnostics
• Scheduled PrM
• Improved tools such as OSI PI
Questions & Answers
Thanks!
• Steve Wright
• Senior Development Associate
• Process and Environmental Analytics
• Bldg 359A
• Eastman Chemical Company
• Phone: 423-229-4060
• Email: [email protected]