Tank Farm Placement in Oil Refinery Material Flow Simulation Models

       In this article, we analyze different schemes of tank farm placement and tank farm layout in refinery and gas processing systems within modern refinery simulation models. The study is based on reusable simulation components, including the flowing tank farm and accumulative tank farm, which are part of the Petroleum Refining Library (PRL). Runtime operation and control of accumulative reservoir parks are described in accumulative tank farm control.These tank farm types differ both in their objectives and in their operational logic. Their operational behavior can be analyzed using different categories of tank farm performance metrics. These modules form a unified framework for flow simulation and process flow simulation and storage tank simulation in oil and gas logistics simulation environments built on the AnyLogic platform. The presented modeling approach is grounded in the development of various refinery and gas processing plant simulation models, as well as in accumulated engineering experience and the operational behavior patterns observed across different industrial configurations and case studies of refinery systems. This article explains where tank farms are placed within refinery simulation models, why different layouts are used, and how each placement affects flow control, buffering, and refinery logistics. The effectiveness of different tank farm layouts can be evaluated using comprehensive tank farm performance metrics, including flow statistics, storage utilization, and operational KPIs collected during simulation. Effective placement alone is insufficient without appropriate reservoir park control strategies.

       Tank farms, as fundamental simulation components, represent critical elements in both real industrial systems and in industrial process modeling of refinery and gas processing facilities. Tank farms are not treated as static storage units, but as active control nodes governing hydrocarbon flows and supporting tank farm operations within the overall refinery material flow system.. Within refinery tank farm layout design and simulation, tank farm models are widely applied as buffering and regulation units, ensuring synchronization between non-uniform inflows and constrained downstream processing units. They also support accumulation, product certification, and shipment operations, particularly in accumulative configurations. The effectiveness of these storage strategies can be assessed using flow statistics, storage statistics, and tank utilization metrics collected during simulation.

       From the perspective of digital twin modeling and AnyLogic-based refinery simulation model development, tank farms act as key decision-making elements that define flow distribution, storage strategies, and system-level constraints.

       Storage strategies can be further improved using dynamic tank reallocation between refinery tank farms. Detailed storage utilization and available storage capacity statistics make it possible to compare alternative tank farm layouts and validate engineering decisions. Each zone requires a specific tank farm arrangement and tank farm configuration, depending on its functional role within the overall flow network topology of the production system. The proposed tank farm control strategy is implemented through simulation rules governing residual levels, pumping rates, and flow distribution. Maintenance constraints can also be incorporated through tank repair simulation.

       In typical tank farm placement and tank farm layout configurations, process (head) units are located downstream of flowing tank farms within refinery and gas processing systems, as incoming feedstock streams often exhibit significant flow rate fluctuations. The flowing tank farm acts as a buffer, absorbing these variations and smoothing the flow before supplying a more stable feed to the downstream process units.
       Within simulation models, this configuration requires solving the problem of optimal distribution of outgoing flow from the tank farm among multiple plants, as well as evaluating the maximum achievable throughput under tank farm and plants constraints.
       During flow simulation, the control logic focuses on determining an optimal withdrawal intensity from the Flowing tank farm that maintains the tank farm residual level within admissible bounds (i.e., above minimum and below maximum thresholds), while preventing overflow conditions or inflow rejection caused by downstream capacity saturation. The outflow rate from the tank farm is determined by the current residual level and the aggregated maximum intake capacity of connected downstream process units, reflecting core principles of capacity constraint modeling within the overall refinery material flow system.

Simulation logic and operating rules
       Within the tank farm simulation model implemented in the AnyLogic-based oil and gas logistics simulation framework, the flow control is defined by the following rules:
       Inflow rate is not constrained by the tank farm and is determined by the upstream node rate (e.g., pipeline or upstream process unit production rate).
       Target residual level is set to the mid-range storage level of the tank farm.
       Outflow rate is constrained by both the pumping system capacity installed in the tank farm and the maximum allowable intake capacity of downstream process units.

       In specific cases of tank farm placement and tank farm layout within refinery and gas processing systems, inlet sections may operate without intermediate tank farm infrastructure. In such configurations, incoming streams are directly routed to process (head) units, which significantly alters the structure and behavior of the overall refinery simulation model.
       Within this configuration, flow simulation is focused on solving the problem of optimal allocation of incoming feedstock streams among multiple process units, with the objective of minimizing unaccepted or rejected flow due to capacity constraints.

        In both configurations (scheme 1 and scheme 2), the evaluation of permissible outgoing flow rates must account not only for the maximum processing capacity of receiving units, but also for a broader set of operational factors, including minimum and maximum operating levels, flow prioritization rules, real-time system load, seasonal variability, feedstock composition, and additional technological constraints within the overall refinery material flow system.

       Within industrial systems, tank farm configuration in downstream sections of refinery operations may be implemented as either flowing or accumulative systems.
       Flowing tank farms are primarily used for process unit buffering, damping internal flow fluctuations, and ensuring temporary operational autonomy units during upstream shutdowns.
       Accumulative tank farms serve a complementary function, providing temporary buffering of intermediate or finished products prior to their transfer to product storage tanks or subsequent processing stages, within the broader framework of oil and gas logistics simulation and industrial system modeling.

       This configuration is used to smooth flow variations between interconnected process units within refinery and gas processing systems, representing a typical pattern of tank farm placement and tank farm layout in modern refinery simulation models. This scheme enables effective decoupling of upstream and downstream unit dynamics through intermediate buffering elements. In most implementations, a bypass line is introduced to divert excess flow from the tank farm into a common collection header when the receiving unit is unable to process the full incoming stream.
       Within this structure, the control strategy of the flowing tank farm is defined by determining an optimal withdrawal intensity that ensures stable operation of the downstream unit while maintaining the tank farm residual within admissible operating limits.

Simulation logic and operating rules
       Within the tank farm simulation model implemented in an AnyLogic-based material flow simulation and process flow simulation environment, the control rules are defined as follows:
       Inflow rate is not constrained by the tank farm and is determined by the production rate of the upstream process unit.
       Residual level is set to the mid-range storage level of the tank farm.
       Outflow rate is constrained by both the pumping system capacity installed in the tank farm and the maximum allowable intake capacity of the downstream.

       This configuration is applied to smooth flow variations between upstream (head) process units and downstream receiving units within refinery and gas processing systems. It represents a specific pattern of tank farm placement and tank farm layout in modern refinery simulation models, where the accumulative tank farm functions as a primary buffering element between process stages.
       In typical implementations, bypass lines are used to divert excess flow into a common collection header when the receiving unit is unable to process the full incoming stream. In addition, recirculation lines may be introduced when complete intake of the flow by the downstream unit is not feasible. The operating level of the accumulative tank farm, together with inflow intensity, must ensure stable and continuous loading of the receiving process unit.
       Within this configuration, control of the accumulative tank farm is based on determining an optimal withdrawal intensity that satisfies downstream capacity requirements while maintaining the tank residual within admissible operational limits.

Simulation logic and operating rules
       Within the accumulative tank farm simulation model implemented in an AnyLogic-based material flow simulation environment, the control rules are defined as follows:
       Inflow rate is not constrained by the tank farm and is determined by the production rate of the upstream process unit.
       Residual level is maintained at a high (near-full) operating state to ensure sufficient buffering capacity and supply continuity within the refinery material flow system.
       Outflow rate is constrained by the pumping system capacity and the maximum allowable intake capacity of the downstream process unit.

       This configuration is used when an accumulative tank farm is introduced as an additional buffering stage for intermediate storage of finished products prior to their transfer to the main product storage tank farm. From a functional perspective, this element is closely related to a product accumulative tank farm; however, in practical implementations, the presence of an intermediate buffering stage may reduce the filling rate of the main product storage system due to delayed flow propagation effects.
       Within real industrial systems, this configuration is often simplified by switching to a direct-flow mode, bypassing intermediate accumulation stages when operational conditions permit. In such cases, the intermediate accumulative tank farm operates as a strategic buffer, enabling the formation of additional product reserves when there is a risk of overflow in the main product storage system. Tank farm operations can be coordinated through request-based production planning. The effectiveness of these planning strategies can be evaluated using request statistics.

Simulation logic and operating rules
       Within the accumulative tank farm simulation model implemented in an AnyLogic-based material flow simulation environment, the control rules are defined as follows:
       Inflow rate is not constrained by the tank farm and is determined by upstream source nodes (process units).
       Residual level may operate either in full storage mode or minimum buffer mode, depending on production planning constraints and target fulfillment strategies. The effectiveness of these planning strategies can be evaluated using request statistics.
       Outflow rate is constrained by the capacity of the installed pumping system, defined as the average achievable throughput rate.

       Downstream (outlet) tank farm systems in refinery and gas processing facilities include both flowing and accumulative configurations. These systems represent an important aspect of tank farm placement and tank farm layout within refinery simulation models, where they function as intermediate and final control nodes for outgoing product streams.
       Flowing tank farms are primarily used to smooth irregularities in outgoing flows from process units before transfer into the main pipeline system. In particular, they help mitigate flow fluctuations and reduce the risk of hydraulic shocks during pipeline feeding, contributing to stable operation of the downstream transportation infrastructure.
       Accumulative tank farms, in turn, are responsible for product accumulation, certification, and batch-based dispatch of finished goods prior to delivery to end consumers. Within material flow simulation, they act as final buffering and logistics control nodes, ensuring correct formation of shipment batches and compliance with operational and quality constraints within the overall refinery material flow system.

       This configuration is used as a buffering stage prior to product transfer into pipeline transport systems. It represents a typical pattern of tank farm placement and tank farm layout within modern refinery simulation models, where the flowing tank farm acts as a flow-smoothing node between multiple upstream process units and downstream transport infrastructure.
       In most operational scenarios, the tank farm receives incoming streams from several process units simultaneously. As a result, it performs the function of damping inflow fluctuations and stabilizing the outgoing flow rate, which is essential for preventing hydraulic shocks in downstream pipeline systems and ensuring stable operation of reservoir “breathing” dynamics under dynamic loading conditions.
       In certain operational modes, the system may operate in a quasi-direct flow regime with minimal accumulation, depending on production conditions and downstream demand profiles.

Simulation logic and operating rules
       Within the tank farm simulation model implemented in an AnyLogic-based material flow simulation environment, the control rules are defined as follows:
       Inflow rate is not constrained by the tank farm and is determined by upstream source nodes (process units).
       Residual level is regulated around a mid-range operating point to ensure stable buffering behavior and system stability.
       Outflow rate is constrained by the capacity of the installed pumping system, defined by minimum and maximum allowable flow rates (t/h), as well as permissible rate-of-change limits per simulation step (typically 50–100 t/h).

       This configuration is used for product accumulation, certification (quality control), and dispatch of finished goods to transportation systems, including truck loading stations, rail loading racks, and pipeline export systems. It represents a typical pattern of tank farm placement and tank farm layout within modern refinery simulation models, where the accumulative tank farm functions as a final logistics buffering and distribution node in the production chain.
       The accumulative tank farm enables the formation of shipment batches according to the configured shipment plans, supports product quality control procedures, and ensures coordinated product release in accordance with production planning requirements and downstream distribution constraints.

Simulation logic and operating rules
       Within the tank farm simulation model implemented in an AnyLogic-based material flow simulation environment, the control rules are defined as follows:
       Inflow rate is not constrained by the tank farm and is determined by upstream source nodes (process units).
       Residual level may operate either in full storage mode or minimum buffer mode, depending on production planning and shipment scheduling requirements.
       Outflow rate is unconstrained when loading rack systems are used; however, it is limited by average discharge capacity when direct pipeline or non-rack export modes are applied.

       All tank farm configurations discussed in this article can be implemented using the Petroleum Refining Library. The library includes both flowing tank farms (called RpFlowing), used for continuous flow regulation between process units, and accumulative tank farms (called RpAccumulative), designed for storage, buffering, product certification, and shipment planning. By combining these reusable components, engineers can reproduce the operational logic of real refinery and gas processing facilities.
       When used together with AnyLogic, Petroleum Refining Library enables the development of digital twin models with virtually any tank farm placement and interconnection scheme. Tank farms can be positioned at refinery inlets, intermediate processing stages, outlet shipping areas, or distributed across the entire material flow network, allowing engineers to model real industrial layouts, evaluate alternative storage strategies, and optimize refinery logistics within a single simulation environment.

       Thus, this article presents the tank farm simulation model as a reusable digital twin component for refinery logistics and the broader oil and gas industry. Implemented within the AnyLogic environment as part of the PRL library, the model is formalized as a reusable simulation component for developing refinery simulation models. The analysis focuses on the functional placement of tank farms across inlet, intermediate, and outlet sections of processing facilities.

       This approach enables consistent and scalable material flow simulation in complex industrial networks, supporting refinery logistics by representing tank farms as buffering and regulating nodes within the overall refinery material flow system and its associated flow network topology.