dubois - isa - myths and mistakes - oct 6c, 2010 - isa aw -cpac release
TRANSCRIPT
7/25/2019 Dubois - IsA - Myths and Mistakes - Oct 6c, 2010 - IsA AW -CPAC Release
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Standards
Certification
Education & Training
Publishing
Conferences & Exhibits
Process Analytics:are there dinosaurs among us?
Myths and mistakes that maycontribute to our extinction
Rob Dubois
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• Rob Dubois is a process analytical consultant based out of Sherwood Park, Canada. He has beenan active writer, presenter and visionary behind the use of smart and automated sampling.
• Rob co-authored (with Peter van Vuuren and Jeff Gunnell) the NeSSI Generation IIspecification which helped lay the groundwork for a dedicated sampling system bus for processanalytical. He has worked with major companies including Dow Chemical, ExxonMobil Chemicaland CF Industries and has been involved with process analytical for over 35 years with rolesranging from maintenance to sampling design, project engineering and R&D.
• Rob is dedicated to process analytical simplification as well as the use of microAnalytical devices.He has started a company to advance these concepts.
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Are we sick of this ‘mantra’ yet?
• 80% of process analytical reliability issues aredue to the sample system. – Poor understanding of sample integrity
– plugged, leaking, fouled?
– Poor understanding of sample temperature – condensing, frozen, two-phase?
– Poor understanding of sample pressure
– vent header fluctuation, perhaps?
• Let‟s take a „pipe to pixel‟ look at myths and
mistakes with process analytical systems
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Myth: analyzer rounds are essential
• today – Of $6 billion spent each
year on processanalytical, approx. 50% is
spent to maintain* – How many people in your
plant look after analyzers?
– Can automation help?
*Source: PAI partners
Diogenes searching for a hydrogen leak
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Myth: Size (and weight) don’t matter
conventional
• Size and weight are nota critical factor with
current design• High infrastructure costs
by-line
• Move closer to theprocess
• Size is important for fieldmaintenance
Conventional sample system designs can be
quite large and involved.
The move to by-line analysis requires smaller, lighter
components.
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Myth: the process interface meet our needs
• We do careful design of sample system components toreduce lag time, yet the 1st process connection canintroduced dead volume
• Redesigned each project – who owns these things!
• Or worse we give an operator a way to stop the flow
Let’s get an industry standard, low volume sample
valve and probe specifically designed for Process Analytical
requirements
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Myth: it’s de rigeur to use DB&B* valves
Cultural norm
• Based on historical problemswith leaking and/or bad valves
• Adds weight and cost
• Bubbler identify leaks
– Fugitive emission source
– Maintenance issue
With automation
• Pressure or flow sensor
• Close coupled design
• Simple on/off valves fine
“landry” loop
AT
* DB&B = double block & bleed
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Myth: Monitoring the analyzer is good enough(Actually the analyzer is only one part of a large system)
SampleSystem Analyzer
Extract & Pre-Condition
Transport
DCS
Utilities
Shelter/House/Enclosure/Container Services &Utilities
Post cond. &disposal
Validate
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Myth: Div/Zone 2 rating is fine for
enclosures handling hazardous fluids
• Enclosures handling hazardous fluids should be “defacto” treated as Div/Zone 1
– “sniff test”
• Not a myth: It‟s difficult and expensive to automate an
analytical system in order to meet multi-nationalhazardous area requirements. Global harmonizationwelcome!!
The penitent
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Myth: 4-20 mA & discrete I/O is the
communication choice for sample systems
• It‟s labour, design and costintensive for use with a multitudeof geographically distributedsensors & actuators in hazardousareas
• Emerging…
– Small, serial bus rated Div/Zone 1
– Capable of 20-30 sensors per node
– Intrinsically safe NeSSI-bus (CAN, I2C)
System designed with conventional 4-20
mA and discrete I/O in a hydrocarbon
processing facility. (Courtesy of Dow
Chemical. Photo by R. Dubois)
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Demonstration of a CAN based sampling
system at ISA EXPO2007. Houston, Texas.(Photo by R. Dubois)
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Myth: Automation done in the DCS
• Better – a local way to handle our signals
• Unmet need the SAM* (real distributed, local control)
– Form “hockey puck” size, Div/Zone 1
– Function PAC** like; serial I/O
– Graphical visualization
– Standard “applets” (e.g. stream switch, system health, etc.)
© Danielle R. Dubois
“Who can solve SAM?”
SAM
*SAM = Sensor Actuator Manager
**PAC = Process Automation Controller
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Programmable Substrate Heater
Myth: Wireless – not on my watch!
V
P
A
F SAM
NeSSI™-bus
Wireless*or wired access
Auxiliary Heating/Cooling
SubstrateT
T
DCS (Operations)
Ethernet LAN (“anLAN”)
(wired today; wireless future)
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Secure, remote connectivity
for maintenance is important!
- Wireless may be useful for
this purpose
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Myth: Thermostats are good enough
conventional
• On/off control typ.
• Blind & dumb
• Dew point problems
automated
• Graphical visualization
• Networked control of heat
tracer, heater, regulator • Dew points and flashes
tightly controlled
Heating systems need to be
tied into a bus system so that
they can be set and viewed
locally or remotely.(Courtesy of Intertec)
The ubiquitous Honeywell thermostat
common to home heating systems. An
explosion proof variation is typically
used with analytical systems.
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Myth: Rotameters, etc. rule (not)
• conventional – Rotameters, pressure and
temperature gauges whichrequire walk-by visual
checking• automated
– Temperature, flow andpressure gauges replaced
with bus-enabled sensors – Graphical visualization
– “Window test”Rotameter replacement: NeSSI-bus-enabled sensor
can measure fluid flow, pressure and temperature,
and serve in Div/Zone 1. (Courtesy of CircorTech)
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Myth: No need to automate flow control
conventional
• Remote pilot valveslocated in a safe area
– Eliminate tubing runs• Needle valves still used
to control pressures andflows
automation
• Bus-enabled solenoidvalve pilots rated for
hazardous areas – Some progress!
• Needle valves replacedby proportional valvesimilar to EPC* in gaschromatographs – So far no productValve control module,
NeSSI-bus enabled.(Courtesy of Swagelok)
*EPC = electronic pressure control
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Myth: Operators need detailed operational
information
• Common practice – Status alarm of analyzer & flow perhaps
– No mechanism to predict failure
• Better
– RED: Analytical system bad – unreliable data – YELLOW: Analytical system needs maintenance
– GREEN: Analytical system good – reliable data
• Give operators a system reliability indication
– “watch test”
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Myth: microAnalytical – easy to deploy
• The reality…it‟s tough – Certifications & hazardous classifications
– Sample systems & analyzer houses
– Reliability
– Interferences and sensitivity – Expensive
– A conservative end user community
– It takes years to penetrate this market
• Is there a simpler way…?
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Menacing complexity! Statue
dedicated to Kafka – Prague,
Czech Republic
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Analytical Engine – are we heading in the
right direction?
• Miniscule sample used
• Integral pressure, temperature control
• Integral filtration; particulate rejection
• microAnalytical ready
• Sample returned to pipe (no venting req.)
• Based on a patent awarded to Dow Chemical
• Complete analytical solution by-line
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Myth or not? Process analytical - the
technology of last resort
• Unless we become morereliable and lower cost wemay become extinct
• We can improve reliability
incrementally throughautomation, but are we justapplying a band-aid?
• What then, needs to done to
move our analyticalmeasurements by-line?
Analyzer installation – Buna, Germany ca. 1951
Courtesy of S. Bach
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