Model predictive control (MPC)
On a polymer reactor, one controller moves temperature, pressure, catalyst feed, and comonomer ratio together through a grade change.
Petrochemicals and polymers
Petrochemical Advanced Process Control
Petrochemical advanced process control (APC) manages ethylene crackers, separation trains, and polymer reactors where many variables interact and quality limits are tight. Atlas Prediction Control restores and sustains APC performance inside the control systems you already run, including grade transition control on polyethylene and polypropylene lines.
Request a Plant Performance ScanNo-cost Plant Performance Scan
Petrochemicals and polymers
Petrochemical Advanced Process Control
Where APC pays off in petrochemicals and polymers
| Unit | Interacting variables and limits | APC objective |
|---|---|---|
| Ethylene cracker furnaces | Coil outlet temperature, feed rate, steam ratio, coking limits | Hold cracking severity at the optimum between runs |
| Cracked gas compressor and separation | Compressor limits, demethanizer and deethanizer pressures, product purity | Maximize ethylene recovery and stay within compressor limits |
| C2 and C3 splitters | Reflux, reboiler duty, tower pressure, product purity | Cut energy use per ton while meeting purity |
| Polyethylene and polypropylene reactors | Temperature, pressure, catalyst feed, comonomer ratio, melt index and density | Shorten grade transitions and reduce off-spec product |
| PTA oxidation and purification | Reactor temperature, air feed, solvent balance, quality limits | Stabilize quality and reduce solvent and energy use |
Signs a petrochemical or polymer unit is ready for APC.
Several variables interact, so moving one loop
disturbs others.
Response times are long, so operators wait
to see the effect of a move.
Product quality or safety limits cap how
hard the unit can be pushed.
Feed composition or rate changes often.
Energy-intensive equipment such as furnaces,
compressors, or reboilers sets the cost of operation.
Operating limits sit conservatively because
operators cannot see how close the unit is to them.
Grade transitions run longer than they used to,
and off-spec material follows each one.
Melt index, Melt Flow Ratio or density is confirmed
by lab samples a few times per shift, so control
acts on stale values.
What Atlas delivers in petrochemicals and polymers
Quality estimation (soft sensors)
A melt index or density soft sensor gives a reading every minute and is recalibrated against each new lab result.
Advanced regulatory control (ARC)
Ratio and feedforward control hold the comonomer to ethylene ratio steady as feed changes.
Custom calculations
Calculated coking severity, compressor margin, or reactor heat balance give the controller limits it can honor.
Monitoring and diagnostics
CLPM ranks loops by time in normal mode, oscillation, and valve health. Atlas Advisor™, where deployed, correlates APC, CLPM, and historian signals.
Lifecycle and performance services
Remote Resident™ rechecks models after catalyst changes and across campaigns.
How an engagement works in petrochemicals and polymers.
step testing on reactors can use automated or in-situ methods on some platforms, which limits disturbance to production.
Assessment
A Plant Performance Scan (2 to 4 hours, remote, no cost) scores the unit. A Plant Audit (2 to 4 days onsite) adds a financial estimate. You provide engineer time and recent operating data. Atlas provides the score, findings, and loss estimate.
Step testing and modeling
Atlas designs and runs step tests in live operation, then builds or recalibrates the models. You provide operations access and test windows. Atlas provides test design, analysis, and models.
Commissioning
Atlas commissions the controller or soft sensor with your operators and validates it in live operation. You provide operator and engineering time and DCS integration support. Atlas provides tuning, validation, and handover.
Performance monitoring
Control Loop Performance Monitoring (CLPM) tracks loop and controller health against live data. A 90-day pilot on an agreed set of loops carries no fee.
Ongoing support
Remote Resident™ keeps models, constraints, and loops aligned as conditions change.
Frequently asked questions
How does APC shorten polymer grade transitions?
APC moves key variables such as reactor temperature,
pressure, catalyst feed, and comonomer ratio in a
coordinated fashion along a planned path. With a
current model and a melt index or density soft sensor,
the unit reaches target properties sooner and makes
less off-spec material. Atlas recalibrates the models
and inferentials that keep transitions short.
What does APC do on an ethylene plant?
On an ethylene plant, APC holds furnace cracking
severity near its optimum between runs, manages
cracked gas compressor limits, and tightens
separation purity in the demethanizer, deethanizer,
and splitters. The aim is higher ethylene recovery
and lower energy use per ton, within coking and
compressor constraints.
How are soft sensors used for melt index?
A melt index soft sensor estimates melt index every
minute from reactor temperature, pressure, hydrogen
ratio, and other measurements. Each new lab result
recalibrates it. Control acts on the estimate between
samples. Atlas builds and maintains these inferentials
as part of APC.
Why does APC performance drift after commissioning?
Catalyst systems age, feed composition shifts,
equipment fouls, and operators widen limits to stay
safe. Models built at commissioning no longer match
the unit, so controllers move to manual. Atlas finds
where alignment was lost, corrects it under live
conditions, and monitors so it holds.
Which petrochemical and polymer units benefit most from APC?
Ethylene cracker furnaces, cracked gas compression
and separation, C2 and C3 splitters, polyethylene
and polypropylene reactors, and PTA oxidation and
purification. Each has interacting variables,
quality limits, and an energy or off-spec cost
that a coordinated controller can reduce.
What does Atlas need to start?
A process or control engineer for a 2 to 4 hour
Plant Performance Scan, a screen share of live
DCS and APC behavior, and recent operating data
such as historian, alarm database, and APC
diagnostics. There is no fee and no purchase
order for the Scan.
Petrochemical Advanced Process Control
Petrochemical advanced process control (APC) manages ethylene crackers, separation trains, and polymer reactors where many variables interact and quality limits are tight. Atlas Prediction Control restores and sustains APC performance inside the control systems you already run, including grade transition control on polyethylene and polypropylene lines.
Request a Plant Performance Scan