IMF is used to describe Facility Assets, where the Facility Assets typically consist of multiple systems interacting with each other. This section will define system and how the structure of a system is reflected in the IMF Models.
Definition: System – A system is a combination of interacting elements organized to achieve one or more stated purpose. [3]
Definition: System Element – A System Element is a member of a set of elements that constitute a system. [3]
The system concept is illustrated in Figure 3. The complexity of the different system elements that constitute a system might vary and the more complex system elements may be considered as a system with its own system elements. This view of a system can be applied recursively, where the system elements are drilled down into systems until a desired level of detail is achieved. The process of drilling down a system element of one system to a system with its own system elements is called a system breakdown. The repeated pattern of system breakdowns is illustrated in Figure 4.
Example: Cooling System
A cooling system for an oil and gas facility might consist of a circulation system for the cooling medium and a heat exchanger with seawater supply. The circulation system can be drilled down into a set of circulation pumps, distribution headers and cooling medium expansion tank. All these system elements in the circulation system can be further drilled down in new system breakdowns (e.g., cooling medium expansion tank system consists of valves and instruments) until the desired level of details is achieved. The desired level of details might vary between the different parties involved in the engineering of a Facility Asset (e.g., the pump is considered a system element by the engineering contractor while the pump supplier needs to perform a system breakdown on the pump).
The system elements interact with each other by sending and receiving medium (e.g., material flow, electric energy, digital information, etc.). A system might interact with other systems, where the system elements of one system sends/receives medium to/from a system element in a different system as illustrated in Figure 5. The interface between the systems defines how the systems interact i.e., the medium and medium states that are allowed to be sent/received.
Example: Cooling System cont.
In the cooling system example, the pump and the heat exchanger interact with each other since the pump sends (pumps) cooling medium to the heat exchanger. The circulation pump is connected to an electric supply; thus, the cooling system interacts with the electrical supply system of the facility.
A repeated use of the principles of system breakdown and interactions gives rise to similar patterns recuring at progressively smaller scales both vertically (system breakdown) and horizontally (system interactions). The pattern is illustrated Figure 6.
IMF Models are created by performing system breakdowns of the intended Facility Asset and modelling the interactions between the resulting system elements. This is performed in tree structures, where the relations between the system elements are described. The interactions between the system elements are modelled by connecting medium streams between terminals on the system elements.
