Material and Energy Balances (CHEN20010)

AIMS

This subject introduces chemical engineering flow sheet calculations, including material balances, energy balances and compositions of mixtures. The concept of conversion of mass is developed as the basis for determining mass flows in chemical processing systems involving chemical reactions and separation systems. Then the concept of conservation of energy is developed as the basis for determining energy flows in and around chemical processing systems, evaluation of enthalpy changes with and without phase change, simplified energy balances for batch, steady-state and adiabatic systems, estimation of heats of reaction, combustion, solution and dilution, energy balances in reacting systems, simultaneous material and energy balances.

This subject provides the basis for all the chemical engineering subjects that follow. The calculations introduced in this subject are the most common type of calculations performed by professional chemical engineers working in all sectors of industry.

The teaching of process safety is critical to any undergraduate chemical engineering program. Students need to understand their responsibilities to themselves, their work colleagues and the wider community. They need to be aware of safe practices and also the consequences that may arise when those safe practices are not followed. This subject introduces students to concepts of process safety and the consequences when safety management systems fail.

INDICATIVE CONTENT

Topics covered include material balances around single process units and groups of units, involving simple systems and recycle streams, and non-reacting and reacting systems. Total, component, and elemental balances are covered. Other topics include systems of units and unit conversion, and compositions of mixtures.

Energy balances: The concepts of energy, work and heat, the units of energy, internal energy, enthalpy, heat capacity, latent heat, evaluation of enthalpy changes. The general energy balance equation, enthalpy balances, system boundaries. Enthalpies of pure components and selection of enthalpy data conditions.

Energy balances and chemical reactions: Heat of reaction, definitions of standard heat of reaction, standard heat of formation, standard heat of combustion. Hess' Law of adding stoichiometric equations. Adiabatic reaction temperature. Heats of solutions and dilution, and use of enthalpy-concentration charts. Simultaneous material and energy balances.

Safety case studies, safe practices, personal and process safety.