Materialbalanser

Materialbalanser, or mass balance, is a fundamental principle in chemical and process engineering applied to account for all material entering, leaving, and accumulating within a defined system. At its core is the mass conservation law: the rate of accumulation within a control volume equals the rate of input minus the rate of output plus any generation or consumption due to chemical reactions. In practice, balances are written for total mass or for each chemical species involved.

To apply a materialbalance, one defines a system boundary or control volume, identifies all material streams, and specifies their flow rates and compositions. Balance equations can be written for total mass or for each component, leading to a set of linear or differential equations. Steady-state balances assume accumulation is zero, yielding algebraic relations; dynamic balances retain accumulation terms and require time-dependent solutions.

Common applications include reactor design, mixing and separation processes, distillation and absorption columns, and plant-wide material accounting. Materialbalances are often performed alongside energy balances to form material and energy balance analyses, especially when phase changes, chemical reactions, or recycle streams are present. Recycle, purge, inert components, and side reactions add complexity and may require additional equations or assumptions.

Practical considerations include measurement uncertainty, unaccounted losses, and changes in conditions (temperature, pressure) that affect densities and compositions. Materialbalanser remain a central tool for process optimization, safety assessment, and environmental reporting, ensuring consistent and verifiable accounting of all material flows within a system.