CHEMICALS

Least cost gasoline blends that stay on spec.

Octane and vapour pressure do not blend linearly, component properties drift and analysers report only every half hour, so recipes are set conservatively and grades are over delivered on every blend. Physics informed property models and a recipe agent take out the giveaway while holding every grade specification.

All case studies
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KEY RESULTS
−9.3%
octane giveaway per blend
−2.6%
average blend cost per tonne
−5.1%
draw on high value components
+6.8%
blends on spec first time
−8.4%
reblends required
6

blend components combined and balanced at the header, from reformate and alkylate to butane and ethanol

0.3 RON

octane prediction error of the property models against the plant analysers, so recipes are tested in software first

under 5 s

to recompute a full on spec recipe online as component qualities move and grades are switched

THE PROBLEM

Blending is nonlinear, so grades are over delivered.

Gasoline blending is nonlinear. Octane and vapour pressure do not blend linearly by volume, so a finished property cannot be read off from a simple weighted average of the components. Component properties also drift as upstream units move and feedstocks change, and analysers report only every half hour. Because the true blend behaviour is hard to predict, recipes are set conservatively and grades are over delivered on octane and on vapour pressure. That margin is value given away on every blend. When a recipe still lands off spec, as when a component is switched, the blend has to be corrected or reblended, which consumes capacity and raises cost further.

01Research octane number across fourteen successive blends against the grade specification of 95.0. The conventional recipe over delivers well above the specification; the optimised policy holds just above it, taking out the giveaway without ever crossing.
Research octane number across fourteen successive blends against the grade specification of 95.0. The conventional recipe over delivers well above the specification; the optimised policy holds just above it, taking out the giveaway without ever crossing.
Blend numberConventionalOptimised
196.395.3
296.295.3
396.595.4
496.395.4
596.495.3
696.495.3
796.495.4
896.295.3
996.395.4
1096.395.4
1196.395.3
1296.595.4
1396.395.4
1496.195.3
Grade spec95
WHAT THE MODEL DOES

Property models of the blend and an agent that proposes recipes.

EntroMetrix builds physics informed property models of the nonlinear blend behaviour, combining simulations and mechanistic blend models with the plant's own measurements and analyser records to capture how octane and the other quality properties respond to each component. A reinforcement learning agent then proposes component recipes online, moving the recipe in small mass balanced steps that hold every grade specification while lowering cost and shrinking giveaway. Because it learns the blend mechanism from data, a component switch or a shift in component quality no longer forces an octane overshoot or a spec breach, and the specifications are held as constraints by a safe reinforcement learning layer that keeps the policy inside grade, tank and component limits. The system is retrospective and offline first, scored against the plant's past blends before any live use.

HOW IT WORKS
Physics informed models: simulations and mechanistic blend models combined with plant and analyser data capture the nonlinear octane and vapour pressure response.
Recipe agent: proposes small component moves with a mass balance that sums to zero.
Least cost objective: rewards cheaper on spec blends across the whole batch horizon.
Specs as constraints: grade limits are held as hard bounds, with breaches penalised in the reward.
Safe RL layer: the policy is kept inside grade, tank and component limits at every step.
Cost against giveaway: surfaces a frontier the blender picks a single operating point from.
02Every feasible recipe the agent evaluated, plotted by blend cost against the share of blends meeting grade first time. The cost frontier is the ideal curve; conventional practice sits off it and the chosen recipe on it, trading blend cost against how reliably the grade is met first time.
Every feasible recipe the agent evaluated, plotted by blend cost against the share of blends meeting grade first time. The cost frontier is the ideal curve; conventional practice sits off it and the chosen recipe on it, trading blend cost against how reliably the grade is met first time.
Blend cost (index)Blends on spec first time (%)
Conventional practice1.1095.6
Chosen recipe0.8997.6
BUILT ON THE DATA YOU ALREADY HOLD

Built from analyser records, demonstrated on nonlinear blending.

The models are built from data the plant already holds. Component and product analyser records, tank movements and the blend history are enough to learn how octane and the other properties respond to each component, and the grade specifications together with the tank and line limits are set with the blending team. Assumptions are documented and reviewed before any recipe is proposed.

DEMONSTRATED ON GASOLINE BLENDING

The method has been demonstrated on nonlinear gasoline blending. A property model of the kind used here predicts octane from the component recipe to within a few tenths of a research octane number, and against that model the agent recomputes a full on spec recipe in seconds. Where a conventional linear recipe overshoots octane and breaches a component limit after a feed change, the learned policy holds every specification through the same change, which is where the giveaway and reblends come out.

03Octane giveaway, blend cost, on spec first time and reblends, baseline against the optimised policy, indexed to the baseline at 100. Giveaway, cost and reblends fall while on spec first time rises.
Octane giveaway, blend cost, on spec first time and reblends, baseline against the optimised policy, indexed to the baseline at 100. Giveaway, cost and reblends fall while on spec first time rises.
BaselineOptimised
Octane giveaway10090.7
Blend cost10097.4
On spec first time100106.8
Reblends10091.6
VALIDATION

Scored against past blends, proposed to the blender.

Validation is retrospective and blind. Recipes are scored against the plant's own past blends before any live use, and the policy is constrained to stay inside grade, tank and component limits, so proposed moves remain within ranges the blender already accepts. The system runs offline, isolated from control systems, and proposes recipes for the blender to approve rather than acting on the plant, with the cost, giveaway and on spec position of each recipe shown.

HOW YOU MAINTAIN CONTROL
Retrospective first: recipes are scored against the plant's own past blends before any live recommendation.
Offline first: trained on recorded data and kept isolated from control systems.
Constraint stratification: simple limits are masked in the environment, quality specs held by safe RL.
Drift tracking: the learning memory is refreshed as component properties move.
Switch robustness: no octane overshoot or spec breach when a component is swapped.
Advisory deployment: recipes are proposed to the blender, with no closed loop actuation.
04Octane held above the grade specification across a run of twelve blends, conventional recipe against the optimised policy. The optimised policy stays just on the safe side of the specification, taking out the margin that is otherwise given away.
Octane held above the grade specification across a run of twelve blends, conventional recipe against the optimised policy. The optimised policy stays just on the safe side of the specification, taking out the margin that is otherwise given away.
Blend numberConventionalOptimised
11.20.3
21.40.3
31.30.3
41.20.3
51.20.4
61.20.4
71.30.3
81.50.3
91.30.4
101.50.3
111.50.2
121.40.4
Grade spec0
OUTCOMES

Least cost blends that stay on spec.

Just above spec, never below

The optimised policy stays just on the safe side of the grade specification, taking out the margin that is otherwise given away.

Less draw on high value components

At equal quality the optimised recipe draws less on the high value components and costs less per tonne.

On spec first time

Learning the blend mechanism lifts the on spec share and takes out reblends.

05Component cost of one grade, conventional recipe against optimised, at equal quality, split between high value and other components. The optimised recipe draws less on the high value components and costs less per tonne.
Component cost of one grade, conventional recipe against optimised, at equal quality, split between high value and other components. The optimised recipe draws less on the high value components and costs less per tonne.
High value componentsOther components
Conventional6040
Optimised5740.4
06Blends meeting grade first time against reblends, baseline against optimised. Learning the blend mechanism lifts the on spec share and takes out reblends.
Blends meeting grade first time against reblends, baseline against optimised. Learning the blend mechanism lifts the on spec share and takes out reblends.
BaselineOptimised
On spec first time8591
Reblends157

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