Success Stories / Evaporators
Unit Optimization Service · Evaporators
A global pectin producer eliminated feed-driven density swings on its MVR evaporator by implementing a Feed-Forward (FFWD) control strategy which improved the Overall Controller Effectiveness (OCE) of its product density control. With concentration now held on target and less steam and power used per ton, the plant realized estimated annualized savings of $343,000.
$343K+
Annualized energy savings
The challenge
The customer concentrates pectin extract in a mechanical vapor recompression (MVR) evaporator before downstream processing. Product concentration, measured as density in %solids, is held by a feedback density controller that adjusts the evaporator's steam flow. The steam flow determines how much water is boiled off per ton of feed.
Feed density into the evaporator varied from batch to batch. Every feed upset passed straight through to the product because the product density controller could only react after the density had already drifted. Feed density disturbances caused high steam use, variable production throughput, and product concentration off specification.
Operators compensated for the resulting swings the way most plants do: by running the unit conservatively and accepting extra steam and power as the cost of keeping product within limits.
Retuning the product density controller alone could not solve the problem. A controller that only measures product density cannot see a change in feed density until it has already affected the product, so the loop's performance was limited by its control strategy.
The results
Steam use
When the feed density changes, heat input is determined to match the water to be removed, so make-up steam is no longer spent over-evaporating.
Power use
As feed density changes, the Feed-Forward (FFWD) controller determines the fan power needed as the vapor load changes.
Product quality
A loop that stays close to Setpoint spends more time within tolerance, raising OCE and reducing off-spec product.
Throughput
Energy and quality gains can come without cutting feed rate, so gains in energy consumption do not require losses to throughput.
Schematic is a simplified representation of the MVR evaporator and its principal control loops. Results based on daily data, Oct 2023 to Feb 2024.
Overall Controller Effectiveness · A Universal Performance Measure
The connection between PID performance and evaporator economics is not theoretical. PlantESPâ„¢ is the leading control loop performance monitoring (CLPM) solution. PlantESP actively monitors PID performance on a plant-wide basis, and it has been successfully deployed on dozens of evaporators.
Among its metrics, PlantESP scores every loop using Overall Controller Effectiveness (OCE). Like OEE, OCE is a composite KPI that assesses three operating attributes (Availability, Performance, Quality) and facilitates the benchmarking of individual PID loops, unit operations, and entire facilities.
≥ 95%
Availability
Time in Normal (auto/cascade)
≥ 90%
Performance
Time Not Saturated (off limits)
≥ 85%
Quality
% Good Error within tolerance
Overall Controller Effectiveness =
Time in Normal × Time Not Saturated × % Good Error
A loop meeting all three thresholds scores 72.7%, the threshold for world-class control. Because the terms multiply, a loop running only 80/80/80 falls to 51.2%. OCE highlights weakness in any one dimension, which is why it gauges control quality and financial exposure alike. Try the OCE calculator
Framing poor performance as lost profit
88%
Density error reduced 1.69 → 0.20 %solids (AAE)
$277K
Annual steam savings: 17.72 → 11.49 kg/MT (−35%)
$66K
Annual power savings: 14.56 → 9.26 kWh/MT (−34%)
A project-based, control-strategy-improvement offering purpose-built for interactive, multi-loop unit operations like an MVR evaporator. Engage to find and fix the losses, then sustain the gains. Explore the service →
Engage · 01–04
01 Kick-off
Prioritize by Strategy
Rank loops, units, and areas against the plant's own goals: density, energy, throughput.
02 Monthly
Identify Bad Actors
Control Station engineers pinpoint that scope's top 10 bad-actor loops every month.
03 Monthly
Tune the Loops
Four hours per month of direct, hands-on tuning support to resolve those loops.
04 As needed
Strategy Change
When tuning cannot close the gap, escalate to a more strategic assessment and action plan.
Sustain · Ongoing
Quarterly
Assess the Value
Financial impact of the 10–20% typical Percent Good Error (PGE) gain from resolved bad-actor tuning.
Monthly
Track OCE Live
Unit Operation Performance Indicators in PlantESP keep the OCE trend visible.
Quarterly
Report to Stakeholders
Benchmark against industry peers for sponsors and non-technical stakeholders.
Annual
Plan the Roadmap
Update a one-to-three year plan for closing whatever performance gap remains.
Keep reading
Decades of domain expertise
Control Station is the process industry's leading provider of controller performance monitoring and analytics. PlantESPâ„¢ supports hundreds of facilities worldwide, backed by an engineering team focused solely on process control.
Start with a performance assessment of your evaporators and other unit operations. Contact us for a no-obligation loop performance assessment and a site-specific estimate of the opportunity hidden in your regulatory controls.
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