Refinery Shipment Scheduling Strategies

Shipment Planning Series
       1. Shipment Planning Fundamentals (complete guide)
       2. Shipment Node Control
       3. Shipment Execution Strategies
       4. Daily vs Monthly Planning
       5. Working Calendars
       6. Shipment Performance Metrics
       7. Why Shipment Planning Should Be Simulated

Solution: Shipment Node Simulation for Petroleum Refining Digital Twins

       The Refinery shipment node is a simulation component that manages product shipments within a refinery digital twin. It transforms refinery shipment plans into actual material flows while tracking shipment execution under real operating constraints. This enables realistic refinery logistics simulation within a refinery digital twin. By linking refinery logistics requirements with production, tank farm inventories, loading infrastructure, and transportation assets, the refinery shipment node enables engineers to evaluate whether refinery shipment plans are operationally achievable under real operating conditions. Shipment execution coordinates refinery transportation between production, storage, and loading infrastructure and collects statistics.

       Production planning defines what products must be shipped during a planning period. Shipment execution defines how and when refinery products are physically transferred through the refinery logistics system. A monthly shipment plan specifies only the required volume.
       The same target can be executed using very different strategies—for example, according to a daily schedule, as quickly as possible, evenly throughout the month, or by manual operator commands. Simulation results provide shipment execution statistics that help compare alternative shipment strategies. Although the planned volume remains the same, each strategy produces different inventory levels, equipment utilization, and operational behavior. Different shipment execution strategies also influence logistics performance, transportation resource utilization, loading schedules, and downstream supply chain operations. Shipment execution is also constrained by real refinery operations. Product availability, pump capacities, pipeline hydraulics, loading infrastructure, operating hours, and maintenance all influence the actual shipment rate. As a result, shipment execution cannot be represented by a simple flow target alone.
       For this reason, refinery digital twins distinguish shipment planning from shipment execution. Planning defines shipment targets, while execution strategies determine how those targets are implemented under real operating conditions and verified through dynamic simulation. Shipment execution represents the operational layer of petroleum product logistics inside the refinery.

       Regardless of the selected execution strategy, refinery shipment node never directly controls the shipment flow. Instead, it continuously requests shipment, while the refinery digital twin calculates the physically achievable flow under current operating conditions.

       The achievable shipment flow within the refinery logistics network depends on:

•        Product availability
•        Tank farm inventory
•        Pump and pipeline capacities
•        Loading infrastructure
•        Working hours
•        Equipment availability and maintenance

       All shipment execution strategies described below operate within these constraints. As these conditions change during the simulation, the shipment rate changes automatically, allowing the digital twin to verify whether shipment plans are operationally achievable.

Automatic shipment scheduling executes shipment plans without operator intervention. Depending on operational objectives, the same shipment target can be executed using different scheduling strategies. Simulation analytics help compare scheduling strategies by analyzing shipment performance, plan completion, and operational efficiency. These scheduling methods represent different approaches to refinery shipment scheduling and logistics execution while using the same refinery digital twin to calculate physically achievable shipment rates.

Daily Scheduling
The shipment plan specifies the required shipment volume for each day. Daily scheduling is commonly used for product deliveries into third-party pipeline systems, blending operations, and refinery dispatch planning. During the simulation, the model attempts to deliver the planned daily quantity while respecting all refinery process constraints. If the required daily target cannot be achieved because of refinery constraints, the shipment remains partially unfulfilled and may be completed later according to the planning policy.

Monthly (As Fast As Possible)
The shipment target is defined for the entire month rather than individual days. The refinery shipment node continuously requests the maximum achievable shipment until the monthly target is completed. The actual shipment rate is determined by the digital twin and is limited by refinery operating conditions, not by the scheduling algorithm. Depending on the configuration, shipments either stop after the target is reached or continue if plan overexecution is permitted. This strategy is commonly used for the shipment of most refinery products, providing a simple and effective way to execute product dispatches.

Monthly (Evenly Distributed)
The monthly shipment target is converted into a nearly constant daily schedule. Available shipment days can calculated after excluding non-working days, holidays, and optional reserve days. The remaining monthly volume is then distributed evenly across the available operating days, providing a stable and predictable shipment rate throughout the month. Missed volumes are not automatically redistributed. It is particularly suitable for product blending, intermediate stream transfers, and other continuous internal refinery operations.

The groupName parameter distinguishes shipment plans for the same product across different nodes in the refinery model. This allows separate plans to control production and shipment activities independently, even when they use the same product.

       Learn the complete refinery shipment planning workflow in Refinery Shipment Planning.

       Not all refinery shipments originate from production plans. Manual shipment execution supports event-driven refinery logistics where shipment requests originate from real operational events rather than production schedules. Emergency transfers, truck loading requests, pipeline batches, or marine cargoes are often initiated manually by operators. The shipment system remains active until the requested quantity has been transferred, after which the shipment is automatically completed and the flow is stopped. The actual shipment rate is determined by the refinery digital twin and remains subject to all process constraints. Manual shipment execution is ideal for modeling operator-controlled logistics, including rail loading, truck dispatch, marine cargoes, pipeline batches, and other event-driven shipment operations.

       Within Petroleum Refining Library (PRL), all shipment strategies are implemented by a single configurable Shipment Node. The selected execution strategy changes only the shipment scheduling logic, while the physical material flow is always calculated by the refinery digital twin.

       For automatic operation, Shipment Node supports several refinery shipment scheduling strategies designed for different logistics objectives (shipmentScheduleType (label: Shipment algorithm)):
        - daily Scheduling – executes shipment plans defined for individual days.
        - monthly (As Fast As Possible) – continuously requests shipment until the monthly target is reached.
        - monthly (Evenly Distributed) – converts a monthly target into a nearly constant daily shipment schedule.

       In addition to automatic scheduling, Shipment Node also supports a manual shipment execution mode (useUserDefinedPumpingPlan (label: Use user-defined pumping plan)). When enabled, manual shipment orders override the automatic scheduling strategy. Each shipment is executed until the specified volume is transferred, after which the flow path is automatically closed and remains inactive until a new manual order is issued.

       The Shipment Node specifies shipment targets while the actual shipment execution is performed dynamically by the refinery digital twin. During simulation, shipment rates are continuously adjusted according to process conditions such as product availability, tank farm inventories, pump capacities, pipeline hydraulics, loading facility capacity, operating calendars, and other technological constraints. As a result, the simulated shipment schedule reflects real refinery operating conditions rather than predefined static shipment calculations.
       Shipment Node reads shipment plans directly from the planning database and automatically switches execution behavior according to the selected scheduling strategy or manual mode. This enables engineers to verify not only whether a shipment plan is optimal, but also whether it can be physically executed under real refinery operating conditions.

       A shipment plan is only valuable if it can be executed. In other words, refinery Shipment Node transforms refinery shipment plans into executable logistics operations, enabling realistic refinery logistics simulation and verification of operational feasibility before implementation.

Continue reading the complete Refinery Shipment Planning Guide guide to learn how shipment plans are created, executed and validated in refinery Digital Twin models.

1. Why are multiple shipment execution strategies needed?
The same monthly shipment target can be executed in different ways depending on operational objectives. Some refineries prioritize stable daily shipments, while others aim to complete shipments as early as possible or execute them manually in response to operational events.

2. Does a shipment execution strategy determine the shipment rate?
No. The execution strategy defines the shipment target, while the actual flow rate is determined by the refinery digital twin according to technological constraints such as product availability, pump capacities, pipeline hydraulics, loading infrastructure, and operating schedules.

3. What is the difference between shipment planning and shipment execution?
Shipment planning specifies the required shipment volumes. Shipment execution defines how and when those volumes are physically transferred through the refinery logistics system. Shipment execution represents the operational layer of refinery logistics responsible for physically moving petroleum products.

4. When should manual shipment execution be used?
Manual shipment execution is appropriate when shipments are initiated by operators rather than predefined schedules, such as rail loading, truck dispatch, marine cargoes, pipeline batches, or special operational transfers.

5. Can shipment plans be completed exactly?
Not always. Actual shipment volumes may differ slightly from planned values because of continuous process operation, equipment limitations, transportation batch sizes, and other operational constraints. Digital twins help determine whether these deviations are acceptable and whether the overall shipment plan remains achievable.