Plug flow reactor model

An idealized reactor model in which fluid moves as parallel elements without axial mixing, while composition changes along the reactor’s length.

Connect

Residence time: The time a fluid element spends inside a reactor or other process system. Each ideal fluid element has the same residence time in steady plug flow.
Chemical reactor: A vessel or system in which chemical reactions take place under controlled conditions. The plug-flow model is one idealized way to describe a chemical reactor.
Tubular reactor: A reactor in which fluid flows through a tube while chemical reactions occur. Long tubes can approximate the model when radial mixing is strong and axial mixing is limited.
Residence time distribution: A function describing the spread of times that fluid elements spend in a system. Ideal plug flow has a single residence time; tracer tests reveal real deviations.
Material balance: An accounting equation that relates material entering, leaving, accumulating, and reacting within a system. A differential material balance along reactor length produces the plug-flow design equation.
Convection: Transport of a substance by the bulk motion of a fluid. Bulk flow carries each fluid element down the reactor while its composition evolves.
Packed-bed reactor: A reactor containing stationary solid particles through which reacting fluid flows. Its fluid phase is often modeled as plug flow, with additional effects from the catalyst bed.
Backmixing: Mixing that transports fluid or material from downstream regions toward upstream regions. Backmixing violates the model’s assumption of no axial mixing.
Rate law: A mathematical expression relating a reaction rate to reactant concentrations and other conditions. The rate law determines how quickly composition changes as fluid advances.
Molecular diffusion: The net movement of molecules from regions of higher concentration to lower concentration. The ideal model excludes axial mixing, though molecular diffusion can still matter in real reactors.