Processtrøm

Processtrøm, or process stream, is a defined quantity of material that moves from one process unit to another within an industrial plant. It serves as the basic carrier of mass and energy in process engineering, linking units such as reactors, heat exchangers, distillation columns, and separators. A processtrøm is described by its state and composition as it travels, and by the conditions under which it exists (temperature, pressure, phase).

Common properties include mass flow rate, molar flow rate, volumetric flow, temperature, pressure, composition (by component or phase fractions), and enthalpy. Streams can be single-phase (gas, liquid, or solid) or multi-phase, and may split or combine at mixers and splitters.

In process flow diagrams, streams are depicted as arrows with labels that identify the stream and sometimes its key properties. They are categorized as feeds, products, recycle streams, bypasses, or side streams. Streams carry material balances and energy balances through the process, and are central to process simulation and optimization.

Modeling and simulation: In process simulators, a stream stores state variables and interacts with unit operations to satisfy mass and energy balances. Accurate property data and consistent units are essential. Streams may be used to model heat recovery, chemical reactions, phase changes, and phase equilibrium in units like distillation or crystallization.

Practical usage: Operators monitor and control processtrøm properties using meters (flow, temperature, pressure), valves, and controllers to ensure product specifications, safety, and efficiency. Streams may be labeled for safety and regulatory compliance, especially when hazardous materials are involved.